Here you can find the Animal of the Month! On the first Monday of each month, a new animal will be featured.
In the form at the bottom of the page, you can submit suggestions for what you want the animal of the week to be.
Thank you and keep visiting!
10/3/11 Raven
Type:BirdDiet:Omnivore Average life span in the wild:13 years Size:24 to 26 in (61 to 66 cm); wingspan, 3.8 to 4.7 ft (1.2 to 1.4 m)Weight:2.3 lbs (1.3 kg) Group name:Flock Did you know?According to legend, if the ravens leave the Tower of London, the fortress and the British kingdom will fall
Common ravens are actually rather remarkable animals. These sleek, black birds are excellent and acrobatic fliers on par with falcons and hawks. Such aerial skills are on display during breeding season, when exciting mating
rituals include an elaborate dance of chases, dives, and rolls.
These intelligent birds were honored by Native Americans and often portrayed as sly pranksters for their playful nature. Known as scavengers, ravens are also effective hunters that sometimes use
cooperative techniques. Teams of ravens have been known to hunt down game too
large for a single bird. They also prey on eggs and nestlings of other birds,
such as coastal seabirds, as well as rodents, grains, worms, and insects. Ravens
do dine on carrion and sometimes on human garbage.
In winter, common ravens may gather in flocks to forage during the day and to
roost at night. During the rest of the year, they are often coupled, or in small
groups. Ravens are believed to mate for life. They build large, stick nests in
which females lay three to seven eggs each spring. Both parents care for their
young, which remain dependent for several months.
Common ravens typically vocalize with a croaking sound, but they boast a
wider repertoire of calls.
Ravens are the largest passerine (perching) birds in North America. They were
once exterminated as pests thought to constitute a threat to game birds and
domestic animals. Today, populations are expanding, and the birds are a familiar
sight across the Northern Hemisphere from the icy Arctic to the Mediterranean
and in urban areas as well.
Common ravens are actually rather remarkable animals. These sleek, black birds are excellent and acrobatic fliers on par with falcons and hawks. Such aerial skills are on display during breeding season, when exciting mating
rituals include an elaborate dance of chases, dives, and rolls.
These intelligent birds were honored by Native Americans and often portrayed as sly pranksters for their playful nature. Known as scavengers, ravens are also effective hunters that sometimes use
cooperative techniques. Teams of ravens have been known to hunt down game too
large for a single bird. They also prey on eggs and nestlings of other birds,
such as coastal seabirds, as well as rodents, grains, worms, and insects. Ravens
do dine on carrion and sometimes on human garbage.
In winter, common ravens may gather in flocks to forage during the day and to
roost at night. During the rest of the year, they are often coupled, or in small
groups. Ravens are believed to mate for life. They build large, stick nests in
which females lay three to seven eggs each spring. Both parents care for their
young, which remain dependent for several months.
Common ravens typically vocalize with a croaking sound, but they boast a
wider repertoire of calls.
Ravens are the largest passerine (perching) birds in North America. They were
once exterminated as pests thought to constitute a threat to game birds and
domestic animals. Today, populations are expanding, and the birds are a familiar
sight across the Northern Hemisphere from the icy Arctic to the Mediterranean
and in urban areas as well.
9/5/11 Manatee
Manatees (family Trichechidae, genus Trichechus) are large, fully aquatic, mostly herbivorous marine mammals sometimes known as sea cows. There are three accepted living species of Trichechidae, representing three of the four living species in the order Sirenia: the Amazonian manatee (Trichechus inunguis), the West Indian manatee (Trichechus manatus), and the West African manatee (Trichechus senegalensis). They measure up to 13 feet (4.0 m) long, weigh as much as 1,300 pounds (590 kg),[1] and have paddle-like flippers. The name manatí comes from the Taíno, a pre-Columbian people of the Caribbean, meaning "breast".[
Manatees have a mass of 400 to 550 kilograms (880 to 1,200 lb), and mean
length of 2.8 to 3 metres (9.2 to 9.8 ft), with maximums of 3.6 metres (12 ft)
and 1,775 kilograms (3,910 lb) seen (the females tend to be larger and heavier).
When born, baby manatees have an average mass of 30 kilograms (66 lb). They have
a large flexible prehensile upper lip. They use the lip to gather food
and eat, as well as using it for social interactions and communications.
Manatees have shorter snouts than their fellow sirenians, the dugongs. Their small, widely-spaced eyes have eyelids
that close in a circular manner. The adults have no incisor or canine teeth, just a set of cheek teeth, which are
not clearly differentiated into molars and premolars. Uniquely among mammals, these teeth are
continuously replaced throughout life, with new teeth growing at the
rear as older teeth fall out from farther forward in the mouth. At any given
time, a manatee typically has no more than six teeth in each jaw of its
mouth.[4] Its tail is
paddle-shaped, and is the clearest visible difference between manatees and
dugongs; a dugong tail is fluked, similar in shape to a that of a whale.
Like horses,
they have a simple stomach, but a large cecum, in which they can digest tough plant matter.
In general, their intestines have typical length about 45 meter, which are
unusually long for animals of their size.
Life history
Half a manatee's day is spent sleeping in the water, surfacing for air
regularly at intervals no greater than 20 minutes. Manatees spend most of the
rest of the time grazing in shallow waters at depths of 1–2 metres (3.3–6.6 ft).
The Florida subspecies (T. m. latirostris) has been known to live up to
60 years.
Swimming
On average, manatees swim at about 5 to 8 kilometres per hour (3.1 to 5.0
mph). However, they have been known to swim at up to 30 kilometres per hour (19
mph) in short bursts.
Intelligence
Manatees are capable of understanding discrimination tasks, and show signs of
complex associated learning and advanced long term memory.[6] They demonstrate
complex discrimination and task-learning similar to dolphins and pinnipeds in acoustic and visual studies.[7]
Reproduction
Manatees typically breed once every two years, gestation lasts about 12 months, and it takes a
further 12 to 18 months to wean the calf. Only a single calf is born at a time
and aside from mothers with their young or males following a receptive female,
manatees are generally solitary creatures.
Manatees have a mass of 400 to 550 kilograms (880 to 1,200 lb), and mean
length of 2.8 to 3 metres (9.2 to 9.8 ft), with maximums of 3.6 metres (12 ft)
and 1,775 kilograms (3,910 lb) seen (the females tend to be larger and heavier).
When born, baby manatees have an average mass of 30 kilograms (66 lb). They have
a large flexible prehensile upper lip. They use the lip to gather food
and eat, as well as using it for social interactions and communications.
Manatees have shorter snouts than their fellow sirenians, the dugongs. Their small, widely-spaced eyes have eyelids
that close in a circular manner. The adults have no incisor or canine teeth, just a set of cheek teeth, which are
not clearly differentiated into molars and premolars. Uniquely among mammals, these teeth are
continuously replaced throughout life, with new teeth growing at the
rear as older teeth fall out from farther forward in the mouth. At any given
time, a manatee typically has no more than six teeth in each jaw of its
mouth.[4] Its tail is
paddle-shaped, and is the clearest visible difference between manatees and
dugongs; a dugong tail is fluked, similar in shape to a that of a whale.
Like horses,
they have a simple stomach, but a large cecum, in which they can digest tough plant matter.
In general, their intestines have typical length about 45 meter, which are
unusually long for animals of their size.
Life history
Half a manatee's day is spent sleeping in the water, surfacing for air
regularly at intervals no greater than 20 minutes. Manatees spend most of the
rest of the time grazing in shallow waters at depths of 1–2 metres (3.3–6.6 ft).
The Florida subspecies (T. m. latirostris) has been known to live up to
60 years.
Swimming
On average, manatees swim at about 5 to 8 kilometres per hour (3.1 to 5.0
mph). However, they have been known to swim at up to 30 kilometres per hour (19
mph) in short bursts.
Intelligence
Manatees are capable of understanding discrimination tasks, and show signs of
complex associated learning and advanced long term memory.[6] They demonstrate
complex discrimination and task-learning similar to dolphins and pinnipeds in acoustic and visual studies.[7]
Reproduction
Manatees typically breed once every two years, gestation lasts about 12 months, and it takes a
further 12 to 18 months to wean the calf. Only a single calf is born at a time
and aside from mothers with their young or males following a receptive female,
manatees are generally solitary creatures.
8/1/11 Kangaroo
Kangaroos are very versatile animals and they are able to live in a variety
of different habitats out there in Australia and Tasmania. Other smaller
macropods can also be found around Tasmania and New Guinea. They are also found
on some islands on the outskirts of Australia. They have started to be found in
places that they never explored before. The reason for this is that they are
looking for food.
Some of them thrive in the woodlands, others in the dry
Savannah desert. Still yet, there are some that are living in the grassy plains
areas. What is interesting is that these animals aren’t only found in Australia
like so many people think. They are even found living along rocky edges and
cliffs.
What you will find is that particular species happen to be in
particular regions. They have been well identified in those selective areas. For
example the Red Kangaroo is mainly found out there around the open plains. They
adapt very well to the dry climate found in many areas of Australia.
Both the
Eastern and Western Grey Kangaroos prefer a climate that offers them more
moisture. That is why they are going to be found in the woods and thick forest
areas. However, due to their natural habitat continually being taken away it is
now known that their habitat also overlaps in those very dry regions with the
Red Kangaroos. They have more of an area that they cover in Australia than any
other species of Kangaroo. This is why they are the one most people are familiar
with.
You may not know it but there are even some species of kangaroos that
live just in trees. They don’t seem to do quite as well there as other types of
animals though. Observing them you will quickly see they are very clumsy. Yet
they are doing what they can to adapt to such an environment in order to
survive. They are found along the Northern Queensland area and into the far
regions of New Guinea.
Experts believe that many smaller species and
subspecies of Kangaroos out there live where you can’t see them. They burrow
underground and only come out on occasion. Therefore it is reasonable to believe
that just about anywhere out there in the wild around Australia you will have
the opportunity to come into contact with different species of Kangaroos. This
can be very exciting if you are in that area then make the most of it.
All
Kangaroos are very adaptable creatures so don’t be surprised if you see
different species out of the element where they are reported to be. They have a
desire to survive and a very instinctive nature for going about doing so. If
they can’t get their basic needs met in a given location then they are going to
continue moving on until they are able to do so.
The serious issue about the
habitat for Kangaroos happens to be the issue of it getting smaller and smaller.
People continue to decide to use that same land for their own needs. This makes
it very hard for these animals to be able to find enough food and shelter for
their survival. Hopefully, efforts out there to preserve their remaining habitat
areas will be a success.
By educating people about what can be done to
protect them more people are taking an interest. The problem is that many people
don’t realize their own actions are creating problems for the habitat of
Kangaroos as well as other animals. When they are able to see this information
before they make such a choice they are going to be less likely to move forward
with it.
The reproduction process is very interesting for the Kangaroos. Male
Kangaroos are called bucks and the females are referred to as does. They young
ones are called joeys. Mating usually takes place during the rainy season of the
year. When the vegetation is green and food is plentiful the mature males and
females will begin to attract each other for mating purposes.
The female is
able to delay the attachment of the embryo to the fetus. This means she is able
to control when she will be pregnant. When she has a joey in her body she won’t
allow that to happen. Should her young die or mature enough to leave her then
she will immediately become pregnant again. As long as conditions are right they
can breed all year long.
The only exception is when there isn’t enough food
or water for survival. This often occurs during drought conditions. Then she
won’t become pregnant at all until the living conditions improve. This is a very
serious situation because it can drastically reduce the population of Kangaroos.
Another element is that the male Kangaroos often can’t produce sperm which is
required for successful mating during the dry season.
The pouch is a very
important part of the female body when it comes to reproduction. The joey is
going to be born about 30 days after conception which is very early. They are
still in a very fragile state of development at that point in time. They are
able to climb into the pouch and then to instinctively suck milk from the
mothers body.
Amazingly, the young joey is no larger than a single lima bean
at that point in time. It is able to find its way into the pouch with no help
from the mother. They are extremely small weighing about .03 ounces and they are
blind. They are also hairless so they need to make that journey quickly if they
are going to survive.
Once there it will latch onto a nipple of the female as
she will have four available. This is where the milk comes from. The mother
Kangaroos have very strong muscles around the pouch. They are able to squeeze
them as the move which prevents their young joey from being tasseled around or
from falling out.
Depending on the species of Kangaroo, the joey will live in
the pouch of the mother for 1 year to 1 ½ years. As they get older they will
start to take time out of the pouch and to explore. Even then though they will
stay very close to their mother for protection.
The mother Kangaroo has been
known to give birth to another joey while she still has an older one in her
pouch though. Then her body is even able to produce too different types of milk.
That for the younger joey contains more fat.
What is also amazing is that she
can actually determine the sex of her young offspring. Research shows that in
the early years when she mates she will want all of her young to be females.
However, as she gets older she wants them to be males. The way in which this
control happens isn’t fully understood.
It is believed that the females
really do enjoy caring for their joeys. They form a very strong attachment to
them. Should one become lost they will spend their time looking for it and not
eating. Many of them seem to become very sad as they get older and aren’t able
to reproduce any longer. During that time they may start to spend more time with
the younger females in the mob that have their own joeys.
An adult Kangaroo
can stand up between 5 and 6 feet tall. They also have an overall weight of
anywhere from 50 pounds to 120 pounds. That is quite a difference but it really
depends on where they live and the particular species that you are talking
about. The males are usually larger than the females within a given species.
The body structure of the Kangaroo is unlike any other animal out there. That is
part of the thrill and fascination that people have with them. The tiny limbs of
them which are in place where human hands would be are short and they don’t have
thumbs on them. The ends of these limbs have very sharp claws on them.
The
legs of a Kangaroo are extremely powerful. The feet are quite large which does
give them an awkward appearance. However, the size of these feet allows them to
be able to leap many feet into the air. They have tendons that are elastic in
nature in their legs and that helps them perform the amazing movements we see.
Each foot has four toes on it.
The tail is very long and thick and this helps
to keep the Kangaroo balanced as they move along. There are quite a few muscles
in the tail which allow the Kangaroo to use it in different ways. For example
they will disperse their weight differently when they want to take a small step
versus a huge leap. The position of the tail will be different during these
movements as well.
Taking a close look at the teeth of Kangaroos is very
interesting. You see the sides of the lower jaw don’t close together. This is
because they have sharp incisors to cut the grass they consume and then molars
to chew it up. Grass is the main element of their diet and it contains large
amounts of silica.
Due to their diet, their teeth often get worn down. Their
bodies are designed to handle this though. As a tooth is ground down it will
then fall out. New teeth that grow in the back of the mouth will then move
forward into empty spaces.
To help regulate their body temperature, the Kangaroos have coarse hair that
is very thick. It has a wooly like texture to it and is offered in various
shades of gray and brown. Some of them even have a reddish tint to them as well.
They have a small head that often looks out of place in comparison to the rest
of the body.
They also have large ears and a very good sense of hearing. The
ears are always in an upright position which does help them to pick up a variety
of sounds. They also have a good sense of smell. Since they don’t have the best
sight they do need to rely upon these other senses to help them survive.
Since Kangaroos are marsupials, the females have a pouch at the front of their
bodies. This is where the young called joeys will stay until they are old enough
to care for themselves. This is one of the easiest ways to be able to tell which
sex any Kangaroo you see happens to be.
As you learn more about the body of
the Kangaroo, you will certainly appreciate all that they have to offer. They
have a unique design that allows them to stand out from other animals in a
variety of ways. Yet their overall anatomy definitely is suited to help them
live in the terrain out there where very few other animals have been able to
successfully call it home.
Kangaroos are very social animals, and they live
in groups called mobs. The overall size of it often depends on their location
and the availability of food and water resources. Some mobs are seen with only a
handful of Kangaroos in it. This is an indicator of a newly formed group that is
just starting out. It can also be an indicator of a larger mob breaking up into
smaller groups for survival.
Other mobs though can end up with about 100
members in it. When that occurs they will also form subgroups within it to
maintain order and social satisfaction. There is a mixture of both males and
females within a mob. However, there is one male that will be dominate meaning
he is in charge. He is the one that decides where the mob will go.
The females within the mob are his to mate with as he chooses. In fact, that is why
other males within the mob will continually try to become aggressive with him.
They want to be able to mate with females. This can often lead to these males
leaving a mob when they reach maturity. They usually head out on their own but
other males and even some females may go along with them.
Most males that do
become the dominant one in a mob will only keep that position for about a year
or so. They simply can’t keep up the level of physical strength and endurance to
continue to fight off the other males that want that position. When that occurs
the other males will force him out of the mob and he will soon die soon
afterwards.
Boxing is a very common type of activity that takes place among
Kangaroos. This is done for a variety of reasons. Sometimes it is merely a
method of playing where they get time to interact with other Kangaroos. Other
times though it is for dominance in a given area. The strongest will have access
to food. The most common reason for boxing though is among the males for the
right to mate.
The females within a mob seem to form a very tight bond with
each other. They show affection and caring towards each other. They have even
been known to take over care for joeys when a mother is dies. They definitely
don’t have the same level of aggression towards each other as the males in a mob
display.
The overall social structure of Kangaroos is one that is very
fascinating. There are plenty of documentaries out there that cover this
particular subject. If you are interested in this element of them consider
viewing them. This can give you an inside look at the world of Kangaroos and
what goes on with them on a daily basis.
However, it is also very important
to note that there are many elements of the Kangaroo social structure that
aren’t well know yet. Even though many people would love to do more research, it
can be time consuming and very expensive. Getting the funding for such research
isn’t very simple at all. In fact, there can be lots of red tape involved when
it comes to such a project.
The other element that makes it difficult is that
the particular social structure can actually be very different for the various
species. There isn’t a set overall structure that they all follow. In fact, if
you have a solid interest in a particular species of kangaroo then you will want
to follow up in this department. Explore the information that is out there
regarding them and their particular social interactions.
What do Kangaroos
Eat? All species of Kangaroos are herbivores which means that they only eat
plants. The specific types of foods that are consumed really depends on the
specific species of Kangaroo that you are talking about. Generally you will find
all species of Kangaroos resting in shady areas during the day. They will move
around looking for food at night and during the early morning hours.
Most
species are grazers which means that they move around consuming different types
of food. They consist of shrubs, grass, and even fungus. The teeth of these
animals are designed to help with the feeding process. For example they have
sharp incisors so they are able to cut the grass very close to the roots. They
also use their molars to grind up the grass.
However, they don’t grind the
food and chew it. Instead, they grind it enough to moisten it and then they
swallow it whole. Then they go through the process of regurgitating it as a form
of cud. From there they will chew it up once again and then completely swallow
it.
Their overall diet consists of being very high in fiber as well as very
low in protein. They are able to do well on such a diet though due to the unique
design of their stomach. It features multiple chambers inside that actually have
bacteria in them. This bacteria helps them to break down the plant cell walls.
That is what allows their bodies to release the nutrition from them into the
body of the Kangaroo.
Kangaroos do need some water for survival but they can
go for several days without any of it. They can also get large amounts of the
water they need through the grass that the eat during the rainy season. When
they do need water and it is scarcely around, they will use their feet to dig
deep into the ground until they find it.
Due to the natural habitat of many
of these Kangaroos continually being taken away by humans, it becomes
increasingly difficult for them to find enough food and water to survive on.
That is a huge concern by those that are interesting in preserving these areas
for the future of Kangaroos.
In many areas, cattle and sheep have also been
introduced to them. As a result the Kangaroos find themselves competing with
these other animals for the same food sources. This can make it very hard for
them to continue living in a given location. As a result they may have to span
out in different directions in order to get their basic needs met.
On a side
note, due to the number of roads that end up being in place between crossing
locations for Kangaroos, there are many mothers killed there. As a way of
helping to protect the young joeys that may be alive in the pouches there are
methods of feeding them so that they can be kept alive.
The age of the joey
will determine what it is fed. As long as it has hair growing in it then it is
old enough to be cared for outside of the mothers pouch. A bottle with milk in
it can offer the baby the nutrition it needs until it is older. Some people do
this on their own and then turn the Kangaroo loose to fend for itself a few
months later.
A better alternative though is to take it to a refuge or a vet
that is willing to care for these orphaned Kangaroos. Then they can be fully
evaluated, cared for, and either released into the wild or placed in
captivity.
of different habitats out there in Australia and Tasmania. Other smaller
macropods can also be found around Tasmania and New Guinea. They are also found
on some islands on the outskirts of Australia. They have started to be found in
places that they never explored before. The reason for this is that they are
looking for food.
Some of them thrive in the woodlands, others in the dry
Savannah desert. Still yet, there are some that are living in the grassy plains
areas. What is interesting is that these animals aren’t only found in Australia
like so many people think. They are even found living along rocky edges and
cliffs.
What you will find is that particular species happen to be in
particular regions. They have been well identified in those selective areas. For
example the Red Kangaroo is mainly found out there around the open plains. They
adapt very well to the dry climate found in many areas of Australia.
Both the
Eastern and Western Grey Kangaroos prefer a climate that offers them more
moisture. That is why they are going to be found in the woods and thick forest
areas. However, due to their natural habitat continually being taken away it is
now known that their habitat also overlaps in those very dry regions with the
Red Kangaroos. They have more of an area that they cover in Australia than any
other species of Kangaroo. This is why they are the one most people are familiar
with.
You may not know it but there are even some species of kangaroos that
live just in trees. They don’t seem to do quite as well there as other types of
animals though. Observing them you will quickly see they are very clumsy. Yet
they are doing what they can to adapt to such an environment in order to
survive. They are found along the Northern Queensland area and into the far
regions of New Guinea.
Experts believe that many smaller species and
subspecies of Kangaroos out there live where you can’t see them. They burrow
underground and only come out on occasion. Therefore it is reasonable to believe
that just about anywhere out there in the wild around Australia you will have
the opportunity to come into contact with different species of Kangaroos. This
can be very exciting if you are in that area then make the most of it.
All
Kangaroos are very adaptable creatures so don’t be surprised if you see
different species out of the element where they are reported to be. They have a
desire to survive and a very instinctive nature for going about doing so. If
they can’t get their basic needs met in a given location then they are going to
continue moving on until they are able to do so.
The serious issue about the
habitat for Kangaroos happens to be the issue of it getting smaller and smaller.
People continue to decide to use that same land for their own needs. This makes
it very hard for these animals to be able to find enough food and shelter for
their survival. Hopefully, efforts out there to preserve their remaining habitat
areas will be a success.
By educating people about what can be done to
protect them more people are taking an interest. The problem is that many people
don’t realize their own actions are creating problems for the habitat of
Kangaroos as well as other animals. When they are able to see this information
before they make such a choice they are going to be less likely to move forward
with it.
The reproduction process is very interesting for the Kangaroos. Male
Kangaroos are called bucks and the females are referred to as does. They young
ones are called joeys. Mating usually takes place during the rainy season of the
year. When the vegetation is green and food is plentiful the mature males and
females will begin to attract each other for mating purposes.
The female is
able to delay the attachment of the embryo to the fetus. This means she is able
to control when she will be pregnant. When she has a joey in her body she won’t
allow that to happen. Should her young die or mature enough to leave her then
she will immediately become pregnant again. As long as conditions are right they
can breed all year long.
The only exception is when there isn’t enough food
or water for survival. This often occurs during drought conditions. Then she
won’t become pregnant at all until the living conditions improve. This is a very
serious situation because it can drastically reduce the population of Kangaroos.
Another element is that the male Kangaroos often can’t produce sperm which is
required for successful mating during the dry season.
The pouch is a very
important part of the female body when it comes to reproduction. The joey is
going to be born about 30 days after conception which is very early. They are
still in a very fragile state of development at that point in time. They are
able to climb into the pouch and then to instinctively suck milk from the
mothers body.
Amazingly, the young joey is no larger than a single lima bean
at that point in time. It is able to find its way into the pouch with no help
from the mother. They are extremely small weighing about .03 ounces and they are
blind. They are also hairless so they need to make that journey quickly if they
are going to survive.
Once there it will latch onto a nipple of the female as
she will have four available. This is where the milk comes from. The mother
Kangaroos have very strong muscles around the pouch. They are able to squeeze
them as the move which prevents their young joey from being tasseled around or
from falling out.
Depending on the species of Kangaroo, the joey will live in
the pouch of the mother for 1 year to 1 ½ years. As they get older they will
start to take time out of the pouch and to explore. Even then though they will
stay very close to their mother for protection.
The mother Kangaroo has been
known to give birth to another joey while she still has an older one in her
pouch though. Then her body is even able to produce too different types of milk.
That for the younger joey contains more fat.
What is also amazing is that she
can actually determine the sex of her young offspring. Research shows that in
the early years when she mates she will want all of her young to be females.
However, as she gets older she wants them to be males. The way in which this
control happens isn’t fully understood.
It is believed that the females
really do enjoy caring for their joeys. They form a very strong attachment to
them. Should one become lost they will spend their time looking for it and not
eating. Many of them seem to become very sad as they get older and aren’t able
to reproduce any longer. During that time they may start to spend more time with
the younger females in the mob that have their own joeys.
An adult Kangaroo
can stand up between 5 and 6 feet tall. They also have an overall weight of
anywhere from 50 pounds to 120 pounds. That is quite a difference but it really
depends on where they live and the particular species that you are talking
about. The males are usually larger than the females within a given species.
The body structure of the Kangaroo is unlike any other animal out there. That is
part of the thrill and fascination that people have with them. The tiny limbs of
them which are in place where human hands would be are short and they don’t have
thumbs on them. The ends of these limbs have very sharp claws on them.
The
legs of a Kangaroo are extremely powerful. The feet are quite large which does
give them an awkward appearance. However, the size of these feet allows them to
be able to leap many feet into the air. They have tendons that are elastic in
nature in their legs and that helps them perform the amazing movements we see.
Each foot has four toes on it.
The tail is very long and thick and this helps
to keep the Kangaroo balanced as they move along. There are quite a few muscles
in the tail which allow the Kangaroo to use it in different ways. For example
they will disperse their weight differently when they want to take a small step
versus a huge leap. The position of the tail will be different during these
movements as well.
Taking a close look at the teeth of Kangaroos is very
interesting. You see the sides of the lower jaw don’t close together. This is
because they have sharp incisors to cut the grass they consume and then molars
to chew it up. Grass is the main element of their diet and it contains large
amounts of silica.
Due to their diet, their teeth often get worn down. Their
bodies are designed to handle this though. As a tooth is ground down it will
then fall out. New teeth that grow in the back of the mouth will then move
forward into empty spaces.
To help regulate their body temperature, the Kangaroos have coarse hair that
is very thick. It has a wooly like texture to it and is offered in various
shades of gray and brown. Some of them even have a reddish tint to them as well.
They have a small head that often looks out of place in comparison to the rest
of the body.
They also have large ears and a very good sense of hearing. The
ears are always in an upright position which does help them to pick up a variety
of sounds. They also have a good sense of smell. Since they don’t have the best
sight they do need to rely upon these other senses to help them survive.
Since Kangaroos are marsupials, the females have a pouch at the front of their
bodies. This is where the young called joeys will stay until they are old enough
to care for themselves. This is one of the easiest ways to be able to tell which
sex any Kangaroo you see happens to be.
As you learn more about the body of
the Kangaroo, you will certainly appreciate all that they have to offer. They
have a unique design that allows them to stand out from other animals in a
variety of ways. Yet their overall anatomy definitely is suited to help them
live in the terrain out there where very few other animals have been able to
successfully call it home.
Kangaroos are very social animals, and they live
in groups called mobs. The overall size of it often depends on their location
and the availability of food and water resources. Some mobs are seen with only a
handful of Kangaroos in it. This is an indicator of a newly formed group that is
just starting out. It can also be an indicator of a larger mob breaking up into
smaller groups for survival.
Other mobs though can end up with about 100
members in it. When that occurs they will also form subgroups within it to
maintain order and social satisfaction. There is a mixture of both males and
females within a mob. However, there is one male that will be dominate meaning
he is in charge. He is the one that decides where the mob will go.
The females within the mob are his to mate with as he chooses. In fact, that is why
other males within the mob will continually try to become aggressive with him.
They want to be able to mate with females. This can often lead to these males
leaving a mob when they reach maturity. They usually head out on their own but
other males and even some females may go along with them.
Most males that do
become the dominant one in a mob will only keep that position for about a year
or so. They simply can’t keep up the level of physical strength and endurance to
continue to fight off the other males that want that position. When that occurs
the other males will force him out of the mob and he will soon die soon
afterwards.
Boxing is a very common type of activity that takes place among
Kangaroos. This is done for a variety of reasons. Sometimes it is merely a
method of playing where they get time to interact with other Kangaroos. Other
times though it is for dominance in a given area. The strongest will have access
to food. The most common reason for boxing though is among the males for the
right to mate.
The females within a mob seem to form a very tight bond with
each other. They show affection and caring towards each other. They have even
been known to take over care for joeys when a mother is dies. They definitely
don’t have the same level of aggression towards each other as the males in a mob
display.
The overall social structure of Kangaroos is one that is very
fascinating. There are plenty of documentaries out there that cover this
particular subject. If you are interested in this element of them consider
viewing them. This can give you an inside look at the world of Kangaroos and
what goes on with them on a daily basis.
However, it is also very important
to note that there are many elements of the Kangaroo social structure that
aren’t well know yet. Even though many people would love to do more research, it
can be time consuming and very expensive. Getting the funding for such research
isn’t very simple at all. In fact, there can be lots of red tape involved when
it comes to such a project.
The other element that makes it difficult is that
the particular social structure can actually be very different for the various
species. There isn’t a set overall structure that they all follow. In fact, if
you have a solid interest in a particular species of kangaroo then you will want
to follow up in this department. Explore the information that is out there
regarding them and their particular social interactions.
What do Kangaroos
Eat? All species of Kangaroos are herbivores which means that they only eat
plants. The specific types of foods that are consumed really depends on the
specific species of Kangaroo that you are talking about. Generally you will find
all species of Kangaroos resting in shady areas during the day. They will move
around looking for food at night and during the early morning hours.
Most
species are grazers which means that they move around consuming different types
of food. They consist of shrubs, grass, and even fungus. The teeth of these
animals are designed to help with the feeding process. For example they have
sharp incisors so they are able to cut the grass very close to the roots. They
also use their molars to grind up the grass.
However, they don’t grind the
food and chew it. Instead, they grind it enough to moisten it and then they
swallow it whole. Then they go through the process of regurgitating it as a form
of cud. From there they will chew it up once again and then completely swallow
it.
Their overall diet consists of being very high in fiber as well as very
low in protein. They are able to do well on such a diet though due to the unique
design of their stomach. It features multiple chambers inside that actually have
bacteria in them. This bacteria helps them to break down the plant cell walls.
That is what allows their bodies to release the nutrition from them into the
body of the Kangaroo.
Kangaroos do need some water for survival but they can
go for several days without any of it. They can also get large amounts of the
water they need through the grass that the eat during the rainy season. When
they do need water and it is scarcely around, they will use their feet to dig
deep into the ground until they find it.
Due to the natural habitat of many
of these Kangaroos continually being taken away by humans, it becomes
increasingly difficult for them to find enough food and water to survive on.
That is a huge concern by those that are interesting in preserving these areas
for the future of Kangaroos.
In many areas, cattle and sheep have also been
introduced to them. As a result the Kangaroos find themselves competing with
these other animals for the same food sources. This can make it very hard for
them to continue living in a given location. As a result they may have to span
out in different directions in order to get their basic needs met.
On a side
note, due to the number of roads that end up being in place between crossing
locations for Kangaroos, there are many mothers killed there. As a way of
helping to protect the young joeys that may be alive in the pouches there are
methods of feeding them so that they can be kept alive.
The age of the joey
will determine what it is fed. As long as it has hair growing in it then it is
old enough to be cared for outside of the mothers pouch. A bottle with milk in
it can offer the baby the nutrition it needs until it is older. Some people do
this on their own and then turn the Kangaroo loose to fend for itself a few
months later.
A better alternative though is to take it to a refuge or a vet
that is willing to care for these orphaned Kangaroos. Then they can be fully
evaluated, cared for, and either released into the wild or placed in
captivity.
7/4/11 Bald Eagle
The bald eagle (Haliaeetus leucocephalus), our national bird, is the only eagle unique to North America. The bald eagle's scientific name signifies a sea (halo) eagle (aeetos) with a white (leukos) head. At one time, the word "bald" meant "white," not hairless. Bald eagles are found throughout most of North America, from Alaska and Canada to northern Mexico. About half of the world's 70,000 bald eagles live in Alaska. Combined with British Columbia's population of about 20,000, the northwest coast of North America is by far their greatest stronghold for bald eagles. They flourish here in part because of the salmon. Dead or dying fish are an important food source for all bald eagles.
Eagles are a member of the Accipitridae family; which also includes hawks, kites, and old-world vultures.
Scientists loosely divide eagles into four groups based on their physical characteristics and behavior. The bald eagle is a sea or fish eagle.
There are two subspecies of bald eagles. The "southern" bald eagle, Haliaeetus leucocephalus leucocephalus, is found in the Gulf States from Texas and Baja California across to South Carolina and Florida, south of 40 degrees north latitude. The "northern" bald eagle, Haliaeetus leucocephalus alascanus,is found north of 40 degrees north latitude across the entire continent. The largest numbers of northern bald eagles are in the Northwest, especially in Alaska. The "northern" bald eagle is slightly larger than the "southern" bald eagle. Studies have shown that "northern" bald eagles fly into the southern states and Mexico, and the "southern" bald eagles fly north into Canada. Because of these finding, the subspecies of "northern" and "southern" bald eagles has been discontinued in recent literature.
Bald eagles were officially declared an endangered species in 1967 in all areas of the United States south of the 40th parallel, under a law that preceded the Endangered Species Act of 1973.
Until 1995, the bald eagle had been listed as endangered under the Endangered Species Act in 43 of the 48 lower states, and listed as threatened in Wisconsin, Minnesota, Michigan, Washington and Oregon. In July of 1995, the US Fish and Wildlife Service upgraded the status of bald eagles in the lower 48 states to "threatened."
On June 28, 2007 the Interior Department took the American bald eagle off the Endangered Species List. The bald eagle will still be protected by the Migratory Bird Treaty Act and the Bald and Golden Eagle Protection Act. The Bald Eagle Protection Act prohibits the take, transport, sale, barter, trade, import and export, and possession of eagles, making it illegal for anyone to collect eagles and eagle parts, nests, or eggs without a permit. Native Americans are able to possess these emblems which are traditional in their culture.
The bald eagle, with its snowy-feathered (not bald) head and white tail, is
the proud national bird symbol of the United States—yet the bird was nearly
wiped out there. For many decades, bald eagles were hunted for sport and for the
"protection" of fishing grounds. Pesticides like DDT also wreaked havoc on
eagles and other birds. These chemicals collect in fish, which make up most of
the eagle's diet. They weaken the bird's eggshells and severely limited their
ability to reproduce. Since DDT use was heavily restricted in 1972, eagle
numbers have rebounded significantly and have been aided by reintroduction
programs. The result is a wildlife success story—the U.S. Fish and Wildlife
Service has upgraded the birds from endangered to threatened.
Though their numbers have grown in much of their range, bald eagles remain
most abundant in Alaska and Canada. These powerful birds of prey use their
talons to fish, but they get many of their meals by scavenging carrion or
stealing the kills of other animals. (Such thievery famously prompted Ben
Franklin to argue against the bird's nomination as the United State's national
symbol.) They live near water and favor coasts and lakes where fish are
plentiful, though they will also snare and eat small mammals.
Bald eagles are believed to mate for life. A pair constructs an enormous
stick nest—one of the bird-world's biggest—high above the ground and tends to a
pair of eggs each year. Immature eagles are dark, and until they are about five
years old, they lack the distinctive white markings that make their parents so
easy to identify. Young eagles roam great distances. Florida birds have been
spotted in Michigan, and California eagles have traveled all the way to
Alaska.
6/6/11 Panda
The Panda (Ailuropoda melanoleuca) is a
member of the bear family and lives in a few remote mountain ranges in Central
China. The panda prefers a cool, damp, isolated habitat and may climb to
altitudes of 11,000 feet to find it. Pandas live in dense, old-growth bamboo
forests with high coniferous leaf canopies. They live a secretive, solitary
existence with perhaps fewer than 1,200 being left in the wild. Because of
their scarcity, their numbers are difficult to count.
Although classified as a carnivore, 99% of a panda's diet is bamboo. They can
eat a number of different varieties of the fibrous plant and need to consume
more than 30 pounds a day. A panda will eat other plants, small rodents, and
fish if they are easily available, but otherwise it spends more than 12 hours a
day eating bamboo. It is not known when in its history the panda adapted to
this mainly vegetarian diet, but its digestive system has not. Bamboo provides
little nutritional value and the panda is inefficient at extracting it. Other
parts of the Panda's anatomy have adapted better. Their esophagus, and stomach
lining has toughened to handle bamboo's woody texture. Their face has broadened
to accommodate stronger jaw muscles and their molars have flattened to be more
efficient at crushing stalks and grinding plant material.
Pandas are immediately recognizable. They have black ears and eye patches,
black hind legs, forelegs, chest and shoulders. The rest of the panda is white.
Pandas are about 2 – 3 feet tall at the shoulder, 4 – 6 feet long and can weigh
180 – 300 pounds. They are roughly the same size as the American Black Bear. It
is the height and shape of the Panda's black "stockings" or the width of black
across its shoulders which help scientists tell individual bears apart. Pandas
possess a double coat. The top layer of fur is coarse, the under layer, dense
and wooly. The fur has an oily feel and deflects water, protecting the panda in
its cold, misty environment.
The panda has developed an elongated wrist bone that acts as an opposable
thumb. This adaptation, combined with flexible forepaws, helps the panda
pincer-grip small shoots and leaves, the parts of its diet that is most
nutritious. While eating, the panda sits on its back-end, splaying its rear
legs out in front of it. This is the most common pose zoo-goers see. The
panda's slow movements and gamin-like appearance make it seem harmless, but it
is just as dangerous as any other bear. In the wild, Pandas will live 18 – 25
years.
The Giant Panda is critically endangered, mainly due to loss of habitat.
Sanctuaries set aside for them are isolated and scattered and the remaining
panda populations find it hard to migrate for food resources and mating. Pandas
are notoriously ineffectual reproducers. Females only ovulate once a year and
so have a narrow window (perhaps 72 hours) in which to conceive. If mating is
successful the cub is born a mere 120 days later. If twins are born, the mother
will choose the strongest to nurture and let the weaker cub die. Panda young
are extremely dependent and vulnerable. They are about the size of a stick of
butter when born (1/900th the size of their mother) and can not even crawl
until they are three months old. Unfortunately panda cubs are susceptible to
disease and can be preyed upon by eagles, leopards or wild dogs when their
mother leaves to feed. A female panda is successful is she rears five cubs to
maturity in her lifetime.
Fun Panda Facts
- Panda Diplomacy began back in the Tang Dynasty. It's a term that describes
China's use of Giant Pandas as gifts to foreign nations. Perhaps the most
famous incident of Panda Diplomacy was when Mao Zedong gifted the United States
with the pandas Ling-Ling and Hsing-Hsing in 1972.
-Panda's only digest 20% of what they eat. The other 80% is excreted. This
means pandas poop over 12 times a day.
- The Western world did not know about Pandas until 1869 when a French
missionary, Pere David, returned to Europe with a panda skin.
- Pandas are good tree-climbers and swimmers.
- Pandas have been on earth for about 3 million years and are considered
"living fossils" because many of the species they co-existed with are now
extinct.
member of the bear family and lives in a few remote mountain ranges in Central
China. The panda prefers a cool, damp, isolated habitat and may climb to
altitudes of 11,000 feet to find it. Pandas live in dense, old-growth bamboo
forests with high coniferous leaf canopies. They live a secretive, solitary
existence with perhaps fewer than 1,200 being left in the wild. Because of
their scarcity, their numbers are difficult to count.
Although classified as a carnivore, 99% of a panda's diet is bamboo. They can
eat a number of different varieties of the fibrous plant and need to consume
more than 30 pounds a day. A panda will eat other plants, small rodents, and
fish if they are easily available, but otherwise it spends more than 12 hours a
day eating bamboo. It is not known when in its history the panda adapted to
this mainly vegetarian diet, but its digestive system has not. Bamboo provides
little nutritional value and the panda is inefficient at extracting it. Other
parts of the Panda's anatomy have adapted better. Their esophagus, and stomach
lining has toughened to handle bamboo's woody texture. Their face has broadened
to accommodate stronger jaw muscles and their molars have flattened to be more
efficient at crushing stalks and grinding plant material.
Pandas are immediately recognizable. They have black ears and eye patches,
black hind legs, forelegs, chest and shoulders. The rest of the panda is white.
Pandas are about 2 – 3 feet tall at the shoulder, 4 – 6 feet long and can weigh
180 – 300 pounds. They are roughly the same size as the American Black Bear. It
is the height and shape of the Panda's black "stockings" or the width of black
across its shoulders which help scientists tell individual bears apart. Pandas
possess a double coat. The top layer of fur is coarse, the under layer, dense
and wooly. The fur has an oily feel and deflects water, protecting the panda in
its cold, misty environment.
The panda has developed an elongated wrist bone that acts as an opposable
thumb. This adaptation, combined with flexible forepaws, helps the panda
pincer-grip small shoots and leaves, the parts of its diet that is most
nutritious. While eating, the panda sits on its back-end, splaying its rear
legs out in front of it. This is the most common pose zoo-goers see. The
panda's slow movements and gamin-like appearance make it seem harmless, but it
is just as dangerous as any other bear. In the wild, Pandas will live 18 – 25
years.
The Giant Panda is critically endangered, mainly due to loss of habitat.
Sanctuaries set aside for them are isolated and scattered and the remaining
panda populations find it hard to migrate for food resources and mating. Pandas
are notoriously ineffectual reproducers. Females only ovulate once a year and
so have a narrow window (perhaps 72 hours) in which to conceive. If mating is
successful the cub is born a mere 120 days later. If twins are born, the mother
will choose the strongest to nurture and let the weaker cub die. Panda young
are extremely dependent and vulnerable. They are about the size of a stick of
butter when born (1/900th the size of their mother) and can not even crawl
until they are three months old. Unfortunately panda cubs are susceptible to
disease and can be preyed upon by eagles, leopards or wild dogs when their
mother leaves to feed. A female panda is successful is she rears five cubs to
maturity in her lifetime.
Fun Panda Facts
- Panda Diplomacy began back in the Tang Dynasty. It's a term that describes
China's use of Giant Pandas as gifts to foreign nations. Perhaps the most
famous incident of Panda Diplomacy was when Mao Zedong gifted the United States
with the pandas Ling-Ling and Hsing-Hsing in 1972.
-Panda's only digest 20% of what they eat. The other 80% is excreted. This
means pandas poop over 12 times a day.
- The Western world did not know about Pandas until 1869 when a French
missionary, Pere David, returned to Europe with a panda skin.
- Pandas are good tree-climbers and swimmers.
- Pandas have been on earth for about 3 million years and are considered
"living fossils" because many of the species they co-existed with are now
extinct.
5/2/11 Blue-footed Booby
The Blue-footed Booby (Sula nebouxii) is a
bird in the Sulidae family which comprises ten species of long-winged seabirds. The natural breeding habitat of the
Blue-footed Booby is tropical and subtropical islands off the Pacific Ocean, most famously, the Galápagos
Islands, Ecuador.
The name booby comes from
the Spanish term bobo, which means
"stupid" or "fool"/"clown". This
is because the Blue-footed Booby is clumsy on
the land, and (like other seabirds), they can be very tame and therefore easily
captured, killed, and
eaten by humans.
The Blue-footed Booby is on average 81 centimeters (32 in)
long and weighs
1.5 kilograms (3.3 lb), with the females slightly larger
than the males. It has
long pointed wings and a wedge shaped tail. They have
strong, thick necks. The
booby's eyes are placed on either side of their
bill and oriented towards the
front. They have excellent binocular vision.
The Blue-footed Booby's eyes are
yellow. The male has more yellow on its
iris than the female. The Blue-footed Booby has
permanently closed nostrils made for diving. They breathe through the corners of
their mouths.
Their feet range from a pale turquoise to a deep aquamarine. Males
and
younger birds have lighter feet than females do.
Blue-footed Boobies are
distributed among the continental coasts of the
eastern Pacific Ocean to the Galápagos
Islands and California.
The Blue-footed Booby is strictly a marine bird. Their only need
for land is
to breed, which they do along rocky coasts.
The courtship of the Blue-footed Booby consists of
the male flaunting his blue
feet and dancing to impress the female. During the
dance,
the male will spread his wings and stamp his feet on the ground. The
Blue-footed
Booby is a monogamous animal although they do have the
potential to be bigamous. They
reunite at their breeding grounds. The breeding
cycle of the booby is every
8 to 9 months. When mating, the female parades and
the male points his head
and tail high to the sky and his wings back to show off
to the female. The
male Blue-footed Booby also makes a high-piping whistle
noise. Males do a
dance to attract the females. The dance includes the males
lifting their
blue feet high and throwing their heads up. The blue-footed booby
is not a
seasonally reproducing species. They are opportunistic
breeders.
Blue-footed Booby with egg and new
young.
The female Blue-footed Booby lays two or three eggs. Both male and
female
take turns incubating the eggs, while the non-sitting bird keeps
watch. Since
the Blue-footed Booby does not have a brooding patch (a patch of bare skin on the
underbelly), it uses its feet to
keep the eggs warm. The chicks cannot control
their body temperature up
until about one month old. Eggs are laid about five
days apart. Blue-foots
are one of only two species of booby that raise more than
one chick. This
may be because of the males specialized diving in shallow
waters. They must
be fed frequently, so the adults constantly hunt for fish. The
chicks feed
off the regurgitated fish in the adult's mouth. If the
parent Blue-footed Booby does
not have enough food for all of the chicks, it
will only feed the biggest
chick, ensuring that at least one will survive.
Boobies may use and defend
two or three nesting sites until they develop a
preference a few weeks
before the eggs are laid. Usually two to three eggs are
laid, and one to two
chicks are hatched. The incubation period is 41–45 days.
They nest on bare
black lava in a small dip in the ground. The female will turn
to face the
sun throughout the day, so the nest is surrounded by excretion.
These nests
are done in large colonies. The male and female share quite a bit of
their
responsibilities. The male will provide food for the young in the first
part
of their life because of his specialized diving. The female will take over
when the demand is higher.
The Blue-footed Booby's diet consists entirely of
fish. Blue-footed Boobies
are specialized fish eaters feeding on small
school fish like sardines, anchovies, mackerel, and flying fish. They also feed on squid and offal. The Blue-foot dives into the ocean,
sometimes from a great height, and swims underwater in pursuit of its prey.
It
hunts singly, in pairs, or in larger flocks. They travel in parties of
about 12
to areas of water with large schools of small fish. When the lead
bird sees a
fish shoal in the water, it will signal the rest of the group
and they will all
dive together to catch the fish. Surprisingly, individuals
do not eat with the
hunting group, preferring to eat on their own, usually
in the early morning or
late afternoon.
When they spot a school of fish,
they will all dive in unison. They will
point their bodies down like an
arrow and dive into the water. Plunge diving can
be done from heights of
33–100 ft (10–30.5 m) and even up to 330 ft (100 m).
These birds hit the
water around 60 mph (97 km/h) and can go to depths of 82 ft
(25 m) below the
water surface. The prey is usually eaten while the bird is
still underwater.
Males and females fish differently which could contribute to
the reasons
that Blue-foots — unlike other boobies — raise more than one young.
The male
is smaller and the tail is larger for its body, which enables the male
to
fish in shallow areas instead of just deep waters. The tail can flatten out
easier enabling him to change direction in the shallow water. The female is
larger and can carry more food. The food is then regurgitated to the young. The
males feed the young for the first part of the incubation period. This is
done
because the males can bring back food quicker than the female. When the
demand
for more food increases, the female provides the food to the
young.
Blue-foots will make raucous or polysyllabic grunts or shouts and thin
whistle noise. The males of the species have been known to throw up their
head
and whistle at a passing, flying female. Their ritual displays are also
a form
of communication.
bird in the Sulidae family which comprises ten species of long-winged seabirds. The natural breeding habitat of the
Blue-footed Booby is tropical and subtropical islands off the Pacific Ocean, most famously, the Galápagos
Islands, Ecuador.
The name booby comes from
the Spanish term bobo, which means
"stupid" or "fool"/"clown". This
is because the Blue-footed Booby is clumsy on
the land, and (like other seabirds), they can be very tame and therefore easily
captured, killed, and
eaten by humans.
The Blue-footed Booby is on average 81 centimeters (32 in)
long and weighs
1.5 kilograms (3.3 lb), with the females slightly larger
than the males. It has
long pointed wings and a wedge shaped tail. They have
strong, thick necks. The
booby's eyes are placed on either side of their
bill and oriented towards the
front. They have excellent binocular vision.
The Blue-footed Booby's eyes are
yellow. The male has more yellow on its
iris than the female. The Blue-footed Booby has
permanently closed nostrils made for diving. They breathe through the corners of
their mouths.
Their feet range from a pale turquoise to a deep aquamarine. Males
and
younger birds have lighter feet than females do.
Blue-footed Boobies are
distributed among the continental coasts of the
eastern Pacific Ocean to the Galápagos
Islands and California.
The Blue-footed Booby is strictly a marine bird. Their only need
for land is
to breed, which they do along rocky coasts.
The courtship of the Blue-footed Booby consists of
the male flaunting his blue
feet and dancing to impress the female. During the
dance,
the male will spread his wings and stamp his feet on the ground. The
Blue-footed
Booby is a monogamous animal although they do have the
potential to be bigamous. They
reunite at their breeding grounds. The breeding
cycle of the booby is every
8 to 9 months. When mating, the female parades and
the male points his head
and tail high to the sky and his wings back to show off
to the female. The
male Blue-footed Booby also makes a high-piping whistle
noise. Males do a
dance to attract the females. The dance includes the males
lifting their
blue feet high and throwing their heads up. The blue-footed booby
is not a
seasonally reproducing species. They are opportunistic
breeders.
Blue-footed Booby with egg and new
young.
The female Blue-footed Booby lays two or three eggs. Both male and
female
take turns incubating the eggs, while the non-sitting bird keeps
watch. Since
the Blue-footed Booby does not have a brooding patch (a patch of bare skin on the
underbelly), it uses its feet to
keep the eggs warm. The chicks cannot control
their body temperature up
until about one month old. Eggs are laid about five
days apart. Blue-foots
are one of only two species of booby that raise more than
one chick. This
may be because of the males specialized diving in shallow
waters. They must
be fed frequently, so the adults constantly hunt for fish. The
chicks feed
off the regurgitated fish in the adult's mouth. If the
parent Blue-footed Booby does
not have enough food for all of the chicks, it
will only feed the biggest
chick, ensuring that at least one will survive.
Boobies may use and defend
two or three nesting sites until they develop a
preference a few weeks
before the eggs are laid. Usually two to three eggs are
laid, and one to two
chicks are hatched. The incubation period is 41–45 days.
They nest on bare
black lava in a small dip in the ground. The female will turn
to face the
sun throughout the day, so the nest is surrounded by excretion.
These nests
are done in large colonies. The male and female share quite a bit of
their
responsibilities. The male will provide food for the young in the first
part
of their life because of his specialized diving. The female will take over
when the demand is higher.
The Blue-footed Booby's diet consists entirely of
fish. Blue-footed Boobies
are specialized fish eaters feeding on small
school fish like sardines, anchovies, mackerel, and flying fish. They also feed on squid and offal. The Blue-foot dives into the ocean,
sometimes from a great height, and swims underwater in pursuit of its prey.
It
hunts singly, in pairs, or in larger flocks. They travel in parties of
about 12
to areas of water with large schools of small fish. When the lead
bird sees a
fish shoal in the water, it will signal the rest of the group
and they will all
dive together to catch the fish. Surprisingly, individuals
do not eat with the
hunting group, preferring to eat on their own, usually
in the early morning or
late afternoon.
When they spot a school of fish,
they will all dive in unison. They will
point their bodies down like an
arrow and dive into the water. Plunge diving can
be done from heights of
33–100 ft (10–30.5 m) and even up to 330 ft (100 m).
These birds hit the
water around 60 mph (97 km/h) and can go to depths of 82 ft
(25 m) below the
water surface. The prey is usually eaten while the bird is
still underwater.
Males and females fish differently which could contribute to
the reasons
that Blue-foots — unlike other boobies — raise more than one young.
The male
is smaller and the tail is larger for its body, which enables the male
to
fish in shallow areas instead of just deep waters. The tail can flatten out
easier enabling him to change direction in the shallow water. The female is
larger and can carry more food. The food is then regurgitated to the young. The
males feed the young for the first part of the incubation period. This is
done
because the males can bring back food quicker than the female. When the
demand
for more food increases, the female provides the food to the
young.
Blue-foots will make raucous or polysyllabic grunts or shouts and thin
whistle noise. The males of the species have been known to throw up their
head
and whistle at a passing, flying female. Their ritual displays are also
a form
of communication.
4/4/11 Duck
Duck is the common name for a number of species in the Anatidae family of birds. The ducks are divided between several subfamilies in the Anatidae family; they do not represent a monophyletic group but a form taxon, since swans and geese are not considered ducks. Ducks are mostly aquatic birds, mostly smaller than the swans and geese, and may be found in both fresh water and sea water.
Ducks are sometimes confused with several types of unrelated water birds with similar forms, such as loons or divers, grebes, gallinules, and coots.
Female Mallard
The word duck comes from Old English *dūce "diver", a derivative of the
verb *dūcan "to duck, bend down low as if to get under something, or
dive", because of the way many species in the dabbling
duck group feed by upending; compare with Dutch duiken and German tauchen "to dive".
This word replaced Old English ened/ænid "duck", possibly to
avoid confusion with other Old English words, like ende "end" with
similar forms. Other Germanic languages still have similar words for "duck", for
example, Dutch eend "duck" and German Ente "duck". The word
ened/ænid was inherited from Proto-Indo-European;
compare: Latin anas "duck", Lithuanian ántis "duck", Ancient Greek nēssa/nētta (νήσσα,
νήττα) "duck", and Sanskrit
ātí "water bird", among others.
Some people use "duck" specifically for adult females and "drake" for adult
males, for the species described here; others use "hen" and "drake",
respectively.
A duckling is a young duck in downy plumage[1] or baby duck;[2] but in the food
trade young adult ducks ready for roasting are sometimes labelled
"duckling".[citation needed] Male Mandarin
Duck
The overall body plan of ducks is elongated and broad, and the ducks are also
relatively long-necked, albeit not as long-necked as the geese and swans. The
body shape of diving ducks varies somewhat from this in being more rounded. The
bill is usually broad and contains serrated lamellae which are particularly well defined in the
filter-feeding species. In the case of some fishing species the bill is long and
strongly serrated. The scaled legs are strong and well developed, and generally
set far back on the body, more so in the highly aquatic species. The wings are
very strong and are generally short and pointed, and the flight of ducks requires fast continuous strokes,
requiring in turn strong wing muscles. Three species of steamer duck are almost flightless, however. Many
species of duck are temporarily flightless while moulting; they seek out protected habitat with good
food supplies during this period. This moult typically precedes migration.
The drakes of northern species often have extravagant plumage, but that is moulted in summer to give a more female-like
appearance, the "eclipse" plumage. Southern resident species typically show less
sexual dimorphism, although there are exceptions like
the Paradise
Shelduck of New Zealand which is both strikingly sexually
dimorphic and where the female's plumage is brighter than that of the male. The
plumage of juvenile birds generally resembles that of the female.
Pecten
along the beak
Ducks exploit a variety of food sources such as grasses, aquatic plants, fish, insects, small
amphibians,[3] worms, and small
molluscs.
Diving ducks and sea
ducks forage deep underwater. To be able to submerge more easily, the
diving ducks are heavier than dabbling ducks, and therefore have more difficulty
taking off to fly.
Dabbling ducks feed on the surface of water or on
land, or as deep as they can reach by up-ending without completely
submerging.[4] Along the edge of
the beak there is a comb-like structure called a pecten. This strains the water squirting from the
side of the beak and traps any food. The pecten is also used to preen
feathers.
A few specialized species such as the mergansers are adapted to catch and swallow large
fish.
The others have the characteristic wide flat beak designed for dredging-type jobs such as pulling up waterweed,
pulling worms and small molluscs out of mud, searching for insect larvae, and
bulk jobs such as dredging out, holding, turning headfirst, and swallowing a
squirming frog. To avoid injury when digging into sediment it has no cere. but the nostrils come out through hard
horn.
Two Mallard ducklings
The ducks are generally monogamous, although these bonds generally last a
single year only. Larger species and the more sedentary species (like fast river
specialists) tend to have pair-bonds that last numerous years. Most duck species
breed once a year, choosing to do so in favourable conditions (spring/summer or wet seasons). Ducks also tend to
make a nest before breeding.
Despite widespread misconceptions, only the females of most dabbling ducks "quack". For example, the scaup – which are diving ducks – make a noise like "scaup" (hence their
name), and even among the dabbling ducks, the males never quack. In general,
ducks make a wide range of calls, ranging from whistles cooing, yodels and
grunts. Calls may be loud displaying calls or quieter contact calls.
A common urban
legend claims that duck quacks do not echo; however, this has been
shown to be false. This myth was first debunked by the Acoustics Research Centre
at the University
of Salford in 2003 as part of the British Association's Festival of Science.[5] It was also
debunked in one of the earlier episodes of the popular Discovery
Channel television show MythBusters.[6]
Male Red-crested
Pochard
Distribution and
habitat
The ducks have a cosmopolitan distribution occurring across most of
the world except for Antarctica. A number of species manage to live on
sub-Antarctic islands like South Georgia and the Auckland Islands. Numerous ducks have managed to
establish themselves on oceanic islands such as Hawaii, New Zealand and Kerguelen, although many of these species and
populations are threatened or have become extinct.
Mallards on ice-covered pool in Hannover, Germany
Some duck species, mainly those breeding in the temperate and Arctic Northern
Hemisphere, are migratory; those in the tropics, however, are generally not.
Some ducks, particularly in Australia where rainfall is patchy and erratic, are
nomadic, seeking out the temporary lakes and pools that form after localised
heavy rain.[citation needed]
Ducks have become an accepted presence in populated areas. Migration patterns
have changed such that many species remain in an area during the winter months.
In spring and early summer ducks sometimes influence human activity through
their nesting; sometimes a duck pair nests well away from water, needing a long
trek to water for the hatchlings: this sometimes causes an urgent wildlife rescue operation (e.g. by the RSPCA) if the duck nested somewhere unsuitable like
in a small enclosed courtyard
Ringed
Teal
Worldwide, ducks have many predators. Ducklings are particularly vulnerable,
since their inability to fly makes them easy prey not only for predatory birds
but also large fish like pike, crocodilians, and other aquatic hunters, including
fish-eating birds such as herons. Ducks' nests are raided by land-based
predators, and brooding females may be caught unaware on the nest by mammals
such as foxes,
or large birds, such as hawks or eagles.
Adult ducks are fast fliers, but may be caught on the water by large aquatic
predators including big fish such as the North American muskie and the European pike. In flight, ducks are safe from all but a few
predators such as humans and the Peregrine Falcon, which regularly uses its speed and
strength to catch ducks.
Ducks are sometimes confused with several types of unrelated water birds with similar forms, such as loons or divers, grebes, gallinules, and coots.
Female Mallard
The word duck comes from Old English *dūce "diver", a derivative of the
verb *dūcan "to duck, bend down low as if to get under something, or
dive", because of the way many species in the dabbling
duck group feed by upending; compare with Dutch duiken and German tauchen "to dive".
This word replaced Old English ened/ænid "duck", possibly to
avoid confusion with other Old English words, like ende "end" with
similar forms. Other Germanic languages still have similar words for "duck", for
example, Dutch eend "duck" and German Ente "duck". The word
ened/ænid was inherited from Proto-Indo-European;
compare: Latin anas "duck", Lithuanian ántis "duck", Ancient Greek nēssa/nētta (νήσσα,
νήττα) "duck", and Sanskrit
ātí "water bird", among others.
Some people use "duck" specifically for adult females and "drake" for adult
males, for the species described here; others use "hen" and "drake",
respectively.
A duckling is a young duck in downy plumage[1] or baby duck;[2] but in the food
trade young adult ducks ready for roasting are sometimes labelled
"duckling".[citation needed] Male Mandarin
Duck
The overall body plan of ducks is elongated and broad, and the ducks are also
relatively long-necked, albeit not as long-necked as the geese and swans. The
body shape of diving ducks varies somewhat from this in being more rounded. The
bill is usually broad and contains serrated lamellae which are particularly well defined in the
filter-feeding species. In the case of some fishing species the bill is long and
strongly serrated. The scaled legs are strong and well developed, and generally
set far back on the body, more so in the highly aquatic species. The wings are
very strong and are generally short and pointed, and the flight of ducks requires fast continuous strokes,
requiring in turn strong wing muscles. Three species of steamer duck are almost flightless, however. Many
species of duck are temporarily flightless while moulting; they seek out protected habitat with good
food supplies during this period. This moult typically precedes migration.
The drakes of northern species often have extravagant plumage, but that is moulted in summer to give a more female-like
appearance, the "eclipse" plumage. Southern resident species typically show less
sexual dimorphism, although there are exceptions like
the Paradise
Shelduck of New Zealand which is both strikingly sexually
dimorphic and where the female's plumage is brighter than that of the male. The
plumage of juvenile birds generally resembles that of the female.
Pecten
along the beak
Ducks exploit a variety of food sources such as grasses, aquatic plants, fish, insects, small
amphibians,[3] worms, and small
molluscs.
Diving ducks and sea
ducks forage deep underwater. To be able to submerge more easily, the
diving ducks are heavier than dabbling ducks, and therefore have more difficulty
taking off to fly.
Dabbling ducks feed on the surface of water or on
land, or as deep as they can reach by up-ending without completely
submerging.[4] Along the edge of
the beak there is a comb-like structure called a pecten. This strains the water squirting from the
side of the beak and traps any food. The pecten is also used to preen
feathers.
A few specialized species such as the mergansers are adapted to catch and swallow large
fish.
The others have the characteristic wide flat beak designed for dredging-type jobs such as pulling up waterweed,
pulling worms and small molluscs out of mud, searching for insect larvae, and
bulk jobs such as dredging out, holding, turning headfirst, and swallowing a
squirming frog. To avoid injury when digging into sediment it has no cere. but the nostrils come out through hard
horn.
Two Mallard ducklings
The ducks are generally monogamous, although these bonds generally last a
single year only. Larger species and the more sedentary species (like fast river
specialists) tend to have pair-bonds that last numerous years. Most duck species
breed once a year, choosing to do so in favourable conditions (spring/summer or wet seasons). Ducks also tend to
make a nest before breeding.
Despite widespread misconceptions, only the females of most dabbling ducks "quack". For example, the scaup – which are diving ducks – make a noise like "scaup" (hence their
name), and even among the dabbling ducks, the males never quack. In general,
ducks make a wide range of calls, ranging from whistles cooing, yodels and
grunts. Calls may be loud displaying calls or quieter contact calls.
A common urban
legend claims that duck quacks do not echo; however, this has been
shown to be false. This myth was first debunked by the Acoustics Research Centre
at the University
of Salford in 2003 as part of the British Association's Festival of Science.[5] It was also
debunked in one of the earlier episodes of the popular Discovery
Channel television show MythBusters.[6]
Male Red-crested
Pochard
Distribution and
habitat
The ducks have a cosmopolitan distribution occurring across most of
the world except for Antarctica. A number of species manage to live on
sub-Antarctic islands like South Georgia and the Auckland Islands. Numerous ducks have managed to
establish themselves on oceanic islands such as Hawaii, New Zealand and Kerguelen, although many of these species and
populations are threatened or have become extinct.
Mallards on ice-covered pool in Hannover, Germany
Some duck species, mainly those breeding in the temperate and Arctic Northern
Hemisphere, are migratory; those in the tropics, however, are generally not.
Some ducks, particularly in Australia where rainfall is patchy and erratic, are
nomadic, seeking out the temporary lakes and pools that form after localised
heavy rain.[citation needed]
Ducks have become an accepted presence in populated areas. Migration patterns
have changed such that many species remain in an area during the winter months.
In spring and early summer ducks sometimes influence human activity through
their nesting; sometimes a duck pair nests well away from water, needing a long
trek to water for the hatchlings: this sometimes causes an urgent wildlife rescue operation (e.g. by the RSPCA) if the duck nested somewhere unsuitable like
in a small enclosed courtyard
Ringed
Teal
Worldwide, ducks have many predators. Ducklings are particularly vulnerable,
since their inability to fly makes them easy prey not only for predatory birds
but also large fish like pike, crocodilians, and other aquatic hunters, including
fish-eating birds such as herons. Ducks' nests are raided by land-based
predators, and brooding females may be caught unaware on the nest by mammals
such as foxes,
or large birds, such as hawks or eagles.
Adult ducks are fast fliers, but may be caught on the water by large aquatic
predators including big fish such as the North American muskie and the European pike. In flight, ducks are safe from all but a few
predators such as humans and the Peregrine Falcon, which regularly uses its speed and
strength to catch ducks.
3/7/11 Gray Wolf
The gray wolf or grey wolf (Canis lupus), often known
simply as the wolf, is the largest extant wild member of the Canidae family. Though once abundant over much of
Eurasia, North Africa and North America, the gray wolf inhabits a reduced
portion of its former range due to widespread destruction of its territory,
human encroachment, and the resulting human-wolf encounters that sparked broad
extirpation. Even so, the gray wolf is regarded
as being of least concern for extinction by the International Union for Conservation of Nature,
when the entire gray wolf population is considered as a whole. Today, wolves are
protected in some areas, hunted for sport in others, or may be subject to
population control or extermination as threats to livestock, people, and
pets.
Gray wolves are social predators that live in nuclear families consisting of
a mated pair which monopolises food and breeding rights, followed by their
biological offspring and, occasionally, adopted subordinates. They primarily
feed on ungulates, which they hunt by wearing them down
in short chases. Gray wolves are typically apex predators throughout their range, with only
humans and tigers posing significant threats to them.
sequencing and genetic drift studies reaffirm that the gray wolf
shares a common ancestry with the domestic dog. A number of other gray wolf subspecies have been identified, though
the actual number of subspecies is still open to discussion.
In areas where human cultures and wolves both occur, wolves frequently
feature in the folklore and mythology of those cultures, both positively and
negatively.
A wolf pack in Yellowstone
National Park
In popular literature, wolf packs are often portrayed as strictly
hierarchical social structures with a breeding "alpha" pair which climbs the social ladder
through fighting, followed by subordinate "beta" wolves and a low ranking
"omega" which bears the brunt of the pack's aggression. This terminology is
based heavily on the behaviour of captive wolf packs composed of unrelated
animals, which will fight and compete against each other for status. Also, as
dispersal is impossible in captive situations, fights become more frequent than
in natural settings. In the wild, wolf packs are little more than nuclear families whose basic social unit consists
of a mated pair, followed by its offspring.
Northern wolf packs tend not to be as compact or unified as those of African wild dogs and spotted hyenas,[64]
though they are not as unstable as those of coyotes.
Southern wolves are more similar in social behaviour to coyotes and dingoes, living largely alone or in pairs.[66] The
average pack consists of 5–11 animals; 1–2 adults, 3–6 juveniles and 1–3
yearlings,
though exceptionally large packs consisting of 42 wolves are known. Wolf packs
rarely adopt other wolves into their fold, and typically kill them. In the rare
cases where strange wolves are adopted, the adoptee is almost invariably a young
animal of 1–3 years of age, while killed wolves are mostly fully grown.[68] The
adoption of a new member can be a lengthy process, and can consist of weeks of
exploratory, non-fatal attacks in order to establish whether or not the newcomer
is trustworthy.
During times of ungulate abundance (migration, calving etc.), different wolf
packs may temporarily join forces.
Wolves as young as five months and as old as five years have been recorded to
leave their packs to start their own families, though the average age is 11–24
months. Triggers for dispersal include the onset of sexual maturity and
competition within the pack for food and breeding.
Mated
pairs usually remain together for life if one of the wolves does not die. Upon
the death of one mated wolf, pairs are quickly re-established. Since males often
predominate in any given wolf population, unpaired females are a rarity. Polygamy does occur, but primarily in captive
situations. Multiple litters are rarely successful, due to infanticide by the pack's females. The
age of first breeding in wolves depends largely on environmental factors; when
food is abundant, or when wolf populations are heavily managed, wolves can rear
pups at younger ages in order to exploit the newly available resources. Captive
wolves have been known to breed as soon as they reach 9–10 months, while the
youngest recorded breeding wolves in the wild were 2 years old. Females are
capable of producing pups every year, with one litter annually being the. Incest rarely occurs, though inbreeding depression has been reported to be a
problem for wolves in Saskatchewan and
Isle
Royal
Estrus typically occurs in late winter, with
older, multiparous females entering estrus 2–3 weeks earlier than younger
females. Before the rut ensues, wolf packs will temporarily dissolve until the
end of the mating season. When
receptive, females will avert the base of their tails to one side, exposing the
vulva. During mating, the pair is locked into a
copulatory tie which may last 5–36 minutes. Because estrus in wolves only lasts
a month, the males do not abandon their mates to find other females to
inseminate as dogs do. During pregnancy, female wolves will remain in a den
located away from the peripheral zone of their territories, where violent
encounters with other packs are more likel Old
females usually whelp
in the den of their previous litter, while younger females typically den near
their birthplace. The gestation period lasts 62–75 days, with pups
usually being born in the summer period The
average litter consists of 5–6 pups. Litters of 14–17 occur 1% of the time.
Litter sizes tend to increase in areas where prey is abundant.
Wolves bear relatively large pups in small litters compared to other canid
species.Pups
are born blind and deaf, and are covered in short soft grayish-brown
fur. They weigh 300–500 grams at birth, and begin to see after 9–12 days. The
milk canines erupt after one month. Pups first leave the den after 3 weeks. At
1.5 months of age, they are agile enough to flee from danger. Mother wolves do
not leave the den for the first few weeks, relying on the fathers to provide
food for them and their young.Unlike wolf mothers, the fathers do not regurgitate the pup's food, but carry
them pieces from a kill. If the mother dies prior to the pups weaning period,
they are suckled by the pack's other females. Pups
begin to eat solid food at the age of 3–4 weeks. Pups have a fast growth rate
during their first four months of life: during this period, the pup's weight can
increase nearly 30 times.
The reproductive behaviour of introduced wolf packs in Yellowstone is unusual,
as they often have multiple breeding females who mate with lone male wolves that
encroach upon the pack territories during the mating season. These so called "Casanova wolves" are young males that, having
failed to procure mates or territories after leaving their natal pack, mate with
the daughters of already established breeding pairs from other packs. Unlike
males from established packs, Casanova wolves do not form pair bonds with the
females they mate with. Because of the great abundance of prey in Yellowstone,
female wolves there can bear multiple litters in this fashion.
Wolves use different places for their diurnal rest; places with cover are
preferred during cold, damp and windy weather, while wolves in dry, calm and
warm weather readily rest in the open. During the autumn-spring period, when
wolves are more active, they willingly lie out in the open, whatever their
location. Actual dens are usually constructed for pups during the summer period.
When building dens, females make use of natural shelters such as fissures in
rocks, cliffs overhanging riverbanks and holes thickly covered by vegetation.
Sometimes, the den is the appropriated burrow of smaller animals such as foxes,
badgers or marmots. An appropriated den is often widened and partly remade. On
rare occasions, female wolves will dig burrows themselves, which are usually
small and short with 1-3 openings.
Wolves do not line their denning places, a likely precaution against
parasites. The
den is usually constructed not more than 500 metres away from a water source.
Resting places, play areas for the pups and food remains are commonly found
around wolf dens. The odour of urine and rotting food emanating from the denning
area often attracts scavenging birds such as magpies and ravens. As there are few convenient places for
burrows, wolf dens are usually occupied by animals of the same family. Though
they mostly avoid areas within human sight, wolves have been known to nest near
domiciles,
paved roads
and railways
Wolves scent-roll to bring scents back to the
pack
Wolves are highly territorial animals, and generally establish territories
far larger than they require to survive in order to assure a steady supply of
prey. Territory size depends largely on the amount of prey available: in areas
with an abundance of prey, the territories of resident wolf packs are smaller.
Wolf packs travel constantly in search of prey, covering roughly 9% of their
territory per day (average 25 km/d or 15 mi/d). The core of their territory is
on average 35 km2 (14 sq mi), in which they
spend 50% of their time. Prey
density tends to be much higher in the territory's surrounding areas. Despite
this higher abundance of prey, wolves tend to avoid hunting in the fringes of
their territory unless desperate, due to the possibility of fatal encounters
with neighboring packs.The
size of their territory may increase when the pack's pups reach the age of 6
months, and thus have the same nutritional requirements as adults. The smallest
territory on record was held by a pack of six wolves in northeastern Minnesota,
which occupied an estimated 33 km2. The largest
was held by an Alaskan pack of ten wolves encompassing a 6,272 km2 area. In some areas, wolves may shift territories during
their prey's migration season.
Wolves defend their territories from other packs through a combination of scent marking, direct attacks and howling (see Communication). Scent marking is used for
territorial advertisement, and involves urination, defecation and ground
scratching. Scent marks are generally left every 240 metres throughout the
territory on regular travelways and junctions. Such markers can last for 2–3
weeks, and
are typically placed near rocks, boulders, trees or the skeletons of large
animals. When
scent marking and howling fail to deter strange wolf packs from entering
another's territory, violent interactions can ensue.
Territorial fights are among the principal causes of wolf mortality: one study
on wolf mortality in Minnesota and the Denali National Park and Preserve concluded that
14–65% of wolf deaths were due to predation by other wolves.In
fact, 91% of wolf fatalities occur within 3.2 km (2.0 mi) of the borders between
neighboring territories.
Because the consequences of trespassing can be fatal, such incursions are
thought to be largely due to desperation or deliberate aggressiveness.
Wolves primarily feed on medium to large sized ungulates (sometimes 10–15 times larger than
themselves[26]),
though they are not fussy eaters. Medium and small sized animals preyed on by
wolves include marmots, hares, badgers, foxes, polecats[disambiguation needed], ground squirrels, mice, hamsters, voles and other rodents, as well as insectivores. They frequently eat waterfowl (particularly during their moulting
period and winter, when their greasy and fatty meat helps wolves build up their
fat reserves) and their eggs.[94][95] When
such foods are insufficient, they will prey on lizards, snakes, frogs, rarely toads and large insects. In times of scarcity, wolves will
readily eat carrion,
visiting cattle burial grounds and slaughter houses.[94] Wolf
packs in Astrakhan
will hunt Caspian seals on the Caspian Sea coastline.[96] Some
wolf packs in Alaska and Western Canada have been observed to feed on salmon.[97] Cannibalism is not uncommon in wolves; during
harsh winters, packs often attack weak or injured wolves, and may eat the bodies
of dead pack members.[98][99][100]
However, they are not known to eat their young as coyotes sometimes do.[84] Humans are rarely, but occasionally preyed upon
(see Attacks on humans).[101][102][103][104]
Wolves will supplement their diet with fruit and vegetable matter; they
willingly eat the berries of mountain ash, lily of the valley, bilberries, blueberries and cowberry. Other fruits include nightshade, apples and pears. They readily visit melon fields during the summer months.[98]
Wolves can survive without food for long periods; two weeks without food will
not weaken a wolf's muscle activity.[35]
In Eurasia, many wolf populations are forced to subsist largely on livestock and garbage in areas with dense human activity,
though wild ungulates such as moose,[105] red deer, roe
deer and wild
boar are still important food sources in Russia and the more
mountainous regions of Eastern Europe. Other prey species include reindeer, mouflon, wisent, saiga, ibex, chamois, wild goats, fallow
deer and musk
deer.[106] The
prey animals of North American wolves have largely continued to occupy suitable
habitats with low human density, and cases of wolves subsisting largely on
garbage or livestock are exceptional. Animals commonly preyed on by North
American wolves include moose, white-tailed deer, elk, mule deer, mountain sheep and caribou.[107] In
North Africa, wolves feed on various cultivated crops and vegetables and
domestic animals.[108]
Hunting and
feeding behaviours
Although wolf packs do cooperate strategically in bringing down prey, they do
not do so as frequently or as effectively as lionesses do; unlike lions, wolves rarely remain
with their pack for more than two years, thus they have less time to learn how
to hunt cooperatively. Contrary to lion prides, food acquisition per wolf
decreases with pack size.[109]
Overall, single wolves or mated pairs typically have higher success rates in
hunting than do large packs. Single wolves have occasionally been observed to
kill large prey such as moose, bison and muskoxen unaided.[110] When
hunting, wolves will attempt to conceal themselves as they approach their prey.
With ungulate herds, they then either attempt to break up the herd, or isolate
one or two animals from it.[111] If
the targeted animal stands its ground, the wolves either ignore it, or try to
intimidate it into running.[112] When
chasing small prey, wolves will attempt to catch up with their prey as soon as
possible. With larger animals, the chase is prolonged, in order to wear the
selected prey out.[110]
Wolves usually give up chases after 1–2 km (0.62-1.3 mi), though one wolf was
recorded to chase a deer for 21 km (13 mi).[32]
Sometimes, a single wolf will distract the herd with its presence, acting as a
decoy, while its pack mates attack from
behind.[113] Wolf
packs may also set up ambush trails; Indian wolves have been observed to chase
gazelle herds through ravines where other wolves lie in wait within holes dug
prior to the hunt,[114]
while Russian wolves will set up ambushes near water
holes, sometimes using the same site repeatedly.[111] Both
Russian and North American wolves have been observed to drive prey onto crusted
ice, precipices, ravines, slopes and steep banks to slow them down.[115]
Mature wolves usually avoid attacking large prey frontally, instead focusing on
the rear and sides of the animal. They kill large prey by biting large chunks of
flesh from the soft perineum area, causing massive blood loss. Such bites can cause wounds 10–15 cm
in length, with three such bites to the perineum usually being sufficient to
bring down a large deer in optimum health.[115] When
attacking moose, they occasionally bleed it to death by biting its soft
nose.[99] With
medium-sized prey such as roe deer or sheep, northern wolves kill by biting the
throat, severing nerve tracks and the carotid artery, thus causing the animal to die
within a few seconds to a minute,[116]
while the smaller southern wolves may grab the animal by the neck and stun it by
jerking its head downward, hitting its nose on the ground.[9] When
prey is vulnerable and abundant, wolves may occasionally surplus kill. Such instances are common in
domestic animals, but rare in the wild. In the wild, surplus killing primarily
occurs during late winter or spring, when snow is unusually deep (thus impeding
the movements of prey)[117] or
during the denning period, when wolves require a ready supply of meat when
denbound.[118]
Medium-sized prey are especially vulnerable to surplus killing, as the swift
throat-biting method by which they are killed allows wolves to quickly kill one
animal and move on to another.[116]
Surplus killing may also occur when adult wolves are teaching their young to
hunt.[119]
The breeding pair typically monopolizes food in order to continue producing
pups. When food is scarce, this is done at the expense of other family members,
especially non-pups.[95][120] This
is in marked contrast to the feeding behaviours of dholes and African wild dogs, who give priority to their
pups when feeding.[121] The
breeding pair typically eats first, though as it is they who usually work the
hardest in killing prey, they may rest after a long hunt and allow the rest of
the family to eat unmolested. Once the breeding pair has finished eating, the
rest of the family will tear off pieces of the carcass and transport them to
secluded areas where they can eat in peace. Wolves typically commence feeding by
consuming the larger internal organs of their prey, such as the heart, liver, lungs and stomach lining. The kidneys and spleen are eaten once they are exposed, followed
by the muscles.[122]
Relationships with other predators
Wolf barking at a brown bear in Juraparc, Vallorbe, Vaud, Switzerland
Wolves typically dominate other canid species in areas where they both occur. In
North America, incidences of wolves killing coyotes are common, with such incidences being
especially common in winter, when coyotes feed on wolf kills. Wolves may attack
coyote den sites, digging out and killing the pups. They rarely eat the coyotes
they kill. There are no records of coyotes killing wolves, though coyotes may
chase wolves if they outnumber them.[123][124] Near
identical interactions have been observed in Eurasia between wolves and golden jackals, with the latter's numbers being
comparatively small in areas with high wolf densities.[123][125][126]
Wolves are the most important predator of raccoon
dogs, killing large numbers of them in the spring and summer
periods.[127]
Wolves also kill red, arctic and corsac
foxes, usually in disputes over carcasses. They may eat the foxes
they kill.[128][129] In
Asia, they may compete with dholes.[130]
Brown bears are encountered by wolves in both
Eurasia and North America. Generally, the outcome of such encounters depends on
context: brown bears typically prevail against wolves in disputes over
carcasses, while wolves mostly prevail against bears when defending their den
sites. Both species will kill each other's young. Wolves will eat the brown
bears they kill, while brown bears seem to only eat young wolves.[131] American black bears occur solely in the
Americas. Wolf interactions with black bears are much rarer than with brown
bears, due to differences in habitat preferences. The majority of black bear
encounters with wolves occur in the species' northern range, with no
interactions being recorded in Mexico. Wolves have been recorded on numerous
occasions to actively seek out black bears in their dens and kill them without
eating them. Unlike brown bears, black bears frequently lose against wolves in
disputes over kills.[132]
While encounters with brown and black bears appear to be common, polar
bears are rarely encountered by wolves, though there are two
records of wolf packs killing polar bear cubs.[133]
Wolves will also kill the cubs of Asian black bears.[134] When
attacking bears in daylight, wolf packs have been known to harry their quarry
and wait till nightfall before making the final assault, as wolves have better
night vision than bears.[135]
Wolves may encounter striped hyenas in Israel and Central Asia, usually in disputes over
carcasses. Hyenas feed extensively on wolf-killed carcasses
in areas where the two species interact. On a one-to-one basis, hyenas dominate
wolves, though wolf packs can drive off single hyenas.[136]
Large wolf populations limit the numbers of small to medium sized felines. Wolves encounter cougars along portions of the Rocky Mountains and adjacent mountain ranges.
Wolves and cougars typically avoid encountering each other by hunting on
different elevations. In winter however, when snow accumulation forces their
prey into valleys, interactions between the two species become more likely.
Although they rarely interact, wolves and cougars will kill each other, with
packs of the former sometimes usurping the latter's kills.[137] They
hunt steppe cats, and may pose a threat to snow
leopards.[138]
Wolves may reduce Eurasian lynx populations.[139]
Other than humans, tigers appear to be the only serious predators of
wolves.[138][140][141][142] In
areas where wolves and tigers share ranges, such as the Russian Far East, the two species typically
display a great deal of dietary overlap, resulting in intense competition. Wolf
and tiger interactions are well documented in Sikhote-Alin, which until the beginning of the
20th century, held very few wolves. It is thought by certain experts that wolf
numbers increased in the region after tigers were largely eliminated during the
Russian colonization in the late 19th and early 20th centuries. This is
corroborated by native inhabitants of the region claiming that they had no
memory of wolves inhabiting Sikohte-Alin until the 1930s, when tiger numbers
decreased. Tigers depress wolf numbers, either to the point of localized extinction or to such low numbers as to
make them a functionally insignificant component of the ecosystem. Wolves appear capable of escaping competitive exclusion from tigers only when human
persecution decreases the latter's numbers. Today wolves are considered scarce
in tiger inhabited areas, being found in scattered pockets, and usually seen
traveling as loners or in small groups. First hand accounts on interactions
between the two species indicate that tigers occasionally chase wolves from
their kills, while wolves will scavenge from tiger kills. Tigers are not known
to prey on wolves, though there are four records of tigers killing wolves
without consuming them.[143] This
competitive exclusion of wolves by tigers has been used by Russian
conservationists to convince hunters in the Far East to tolerate the big cats,
as they limit ungulate
populations less than wolves, and are effective in controlling the latter's
numbers.[144]
Body language
Postural communication in wolves is composed of a variety of facial
expressions, tail positions and piloerection.[61] Aggressive or
self assertive wolves are characterised by their slow and deliberate movements,
high body posture and raised hackles, while submissive ones carry their bodies
low, sleeken their fur and lower their ears and tail.[145] When breeding
males encounter subordinate family members, they may stare at them, standing
erect and still with their tails horizontal to their spine.[146] The pre-caudal
scent glands may play a role in expressing aggression, as combative wolves will
raise the base of their tails whilst drooping the tip, thus positioning the
scent glands at the highest point.[147]
Two forms of submissive behaviour are recognised: passive and active. Passive
submission usually occurs as a reaction to the approach of a dominant animal,
and consists of the submissive wolf lying partly on its back and allowing the
dominant wolf to sniff its anogenital area. Active submission occurs often as a
form of greeting, and involves the submissive wolf approaching another in a low
posture, and licking the other wolf's face.[148]
When wolves are together, they commonly endulge in behaviours such as nose
pushing, jaw wrestling, cheek rubbing and facial licking. The mouthing of each
other's muzzles is a friendly gesture, while clamping on the muzzle with bared
teeth is a dominance display. Dominant wolves may assert themselves by
straddling over a subordinate family member.[149] At a kill,
wolves will protect the carcass from afar from other wolves by flattening their
ears outwardly, thus indicating that they are covering something belonging to
them.[150]
Problems
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help.
Wolves howl to assemble the pack (usually before and after hunts), to pass on
an alarm (particularly at a den site), to locate each other during a storm or
unfamiliar territory and to communicate across great distances.[151] Howling
consists of a fundamental frequency which may lie between 150 and 780 Hz, and
consists of up to 12 harmonically related overtones. The pitch usually remains
constant or varies smoothly, and may change direction as many as four or five
times.[24] Wolves from
different geographic locations may howl in different fashions; the howls of
European wolves are much more protracted and melodious than those of North
American wolves, whose howls are louder and have a stronger emphasis on the
first syllable. The two are however mutually intelligible, as North American wolves have
been recorded to respond to European-style howls made by biologists.[152]
Wolf howls are generally indistinguishable from those of large dogs.[153] Male wolves
give voice through an octave,
passing to a deep bass with a stress on "O", while females produce a
modulated nasal baritone
with stress on "U". Pups almost never howl, while yearling wolves produce howls
ending in a series of dog-like yelps.[154]
Howls used for calling pack mates to a kill are long, smooth sounds similar to
the beginning of the cry of a horned
owl. When pursuing prey, they emit a higher pitched howl, vibrating
on two notes. When closing in on their prey, they emit a combination of a short
bark and a howl.[153] When howling
together, wolves harmonize rather than chorus on the same note, thus creating
the illusion of there being more wolves than there actually are.[151] Lone wolves
typically avoid howling in areas where other packs are present.[155] Wolves do not
respond to howls in rainy weather and when satiated.[154]
Other
vocalisations
Other vocalisations of wolves are usually divided into three categories:
growls, barks and whines.[156] Barking has a
fundamental frequency between 320–904 Hz,[24] and is usually
emitted by startled wolves. Wolves do not bark as loudly or continuously as dogs
do, but will bark a few times and retreat from perceived danger.[156] In captivity,
wolves may learn to bark more often if they hear dogs doing so.[157]
Growling has a fundamental frequency of 380–450 Hz,[24] and is usually
emitted during food challenges. Pups commonly growl when playing. One variation
of the howl is accompanied by a high pitched whine, which precedes a lunging
attack.[151] Whining is
associated with situations of anxiety, curiosity, inquiry and intimacy such as
greeting, feeding pups and playing.[156]
The gray wolf was once the world's most widely distributed mammal,
living north of 15°N latitude in North America and 12°N in Eurasia.[168]
Wolves tend to have difficulty adapting to human induced changes, and are often
referred to as an indicator species; a species delineating an ecoregion or indicating an environmental condition such as a disease outbreak,
pollution, species competition, or climate change. Wolves do not seem to be able
to adapt as readily to expanding civilization the way coyotes do. While human
expansion has seen an increase in the latter's numbers, it has caused a drop in
those of the former.[169]
Despite not being at risk for extinction, local populations of wolves are
still threatened. One such threat is genetic bottlenecking caused by population
fragmentation.[163] Human
populations have isolated small pockets of animals, which then suffer the
effects of inbreeding. Studies have shown that the reproduction rate in wolves
is strongly related to genetic diversity.[170]
Isolated wolf populations are greatly affected by the introduction of the
alleles of even a single additional wolf.[163]
With the exception of the Great Britain and Ireland, wolves were widespread in Europe during the 18th century. Wolves were
exterminated from all central and northern European countries during the 19th
century and the post World War II period. Remnant populations remain in Portugal, Spain, Italy, Greece and Finland, though Eurasian wolves have been recovering
naturally in several parts of Europe; recolonising France, Germany, Sweden and Norway. The largest populations now occur in eastern Europe, primarily in Romania, the Balkans and Poland.[171]
Wolf populations generally seem to be stable or increasing in most, but not
all, Bern Convention nations. Limiting factors in member
nations include a lack of acceptance of wolves (particularly in areas where they
have made a comeback) due to concerns on livestock and dog predation and
competition with hunters. Although properly regulated wolf harvests and control
have been largely accepted as compatible with maintaining wolf numbers to
economically acceptable levels, overhunting and poaching are recognised as the
main limiting factor in European wolf populations.[172]
With the exception of Israel and Saudi Arabia, there is little information available
on wolves in the Middle
East. The Arabian Peninsula is home to an estimated 300–600
wolves which, though hunted year round in all Middle Eastern countries except
Israel, are relatively stable and protected by the inaccessibility of the
northern mountains and central and northern deserts. In India, wolves are classed as endangered,
and number an estimated 800-3,000 individuals scattered among several remnant
populations. In China
and Mongolia, wolves are not protected except in
reserves.[173]
Wolves once ranged over much of North America north of Mexico City, save for parts of California. Today, their status varies by country,
state and province. Canadian and Alaskan wolves number in thousands and are in
excellent biological condition. Wolves have expanded from Canada to the northern
Rocky Mountains since the 1970s, establishing
themselves southward in Montana, Washington,
Idaho and Wyoming. In 1994, wolves from Alberta and British Columbia were captured and introduced into Yellowstone
National Park, where they had been extinct since the 1930s. A similar
introduction took place in 1998 in the Apache National Forest in Arizona.[174]
A small, isolated group of wolves on Isle Royale is believed to be suffering
from the effects of reduced genetic variability. In 1991, the population was
reduced from 50 to 12 wolves. Studies have shown that this reduction has
coincided with a 50% loss of allozyme heterozygosity.[175]
The presence of wolves in Egypt, Libya
and Ethiopia was confirmed in 2011, when a comparison was
made between the MtDNA sequences of golden jackals, Holarctic wolves (most
modern wolves are of this ancestry), the Indian wolf, and the Himalayan wolf
(which are considered older lineages than the main Holarctic wolf lineage)
revealed that North African wolves are more closely related to Indian and
Himalayan wolves than they are to golden jackals, a species which they were
associated with in the past.[176]
Diseases and
parasites
Illustration of the diseased jawbone of a young
wolf from Oreston
Because wolves travel great distances, they may play an important role in
spreading and maintaining diseases in certain areas. Infectious diseases spread
by wolves include brucellosis, tularemia, listeriosis and anthrax. Wolves may also suffer from rabies: wolves are a major host for the disease in
Russia, Iran, Afghanistan, Iraq and India.[177] Canine distemper seems to only pose a serious problem
for wolves in Canada and Alaska.[178]
Wolves also carry the Canine coronavirus, with infections being most
prevalent in winter months.[179]
However, gray wolf populations are remarkably resilient against disease
outbreaks. Usually, a wolf displaying the first symptoms of disease will leave
its pack, thus preventing the sickness from spreading to its pack mates. Wolves
in the former Soviet Union have been recorded to carry over 50 different
parasite species.[177] Ticks
carried by wolves include Ixodes ricinus, Dermacentor pictus and Sarcoptes scabiei (or mange mite). Unlike foxes, wolves rarely develop full
blown mange. Other ectoparasites include biting lice, sucking lice and the fleas Pulex
irritans and Ctenocephalides canis. Endoparasites include nematodes such as Toxascaris leonina and T.
canis.[180] Wolves are also
carriers of Trichinella spiralis, the prelevance of which is
significantly related to age.[181]
Other endoparasites include cestodes such as Taenia pisiformis, T. hydatigena, Echinococcus
granulosus, Mesocestoidea lineatus, Dioctophyme renale and the adult phase of
Multiceps multiceps.[180]
Wolves may carry Neospora caninum, which is of particular concern
to farmers, as the disease can be spread to livestock; infected animals being
three to thirteen times more likely to abort than those not infected.[182] Wolves
suffering from tapeworms may deliberately forego eating fresh meat
in favour of putrified flesh, in order to rid themselves of the parasites.[183]
Wolves are highly resistant to radiation poisoning, as evidenced by wolves thriving
in the zone of alienation north of Chernobyl,
despite feeding extensively on highly radioactive ungulates.[
simply as the wolf, is the largest extant wild member of the Canidae family. Though once abundant over much of
Eurasia, North Africa and North America, the gray wolf inhabits a reduced
portion of its former range due to widespread destruction of its territory,
human encroachment, and the resulting human-wolf encounters that sparked broad
extirpation. Even so, the gray wolf is regarded
as being of least concern for extinction by the International Union for Conservation of Nature,
when the entire gray wolf population is considered as a whole. Today, wolves are
protected in some areas, hunted for sport in others, or may be subject to
population control or extermination as threats to livestock, people, and
pets.
Gray wolves are social predators that live in nuclear families consisting of
a mated pair which monopolises food and breeding rights, followed by their
biological offspring and, occasionally, adopted subordinates. They primarily
feed on ungulates, which they hunt by wearing them down
in short chases. Gray wolves are typically apex predators throughout their range, with only
humans and tigers posing significant threats to them.
sequencing and genetic drift studies reaffirm that the gray wolf
shares a common ancestry with the domestic dog. A number of other gray wolf subspecies have been identified, though
the actual number of subspecies is still open to discussion.
In areas where human cultures and wolves both occur, wolves frequently
feature in the folklore and mythology of those cultures, both positively and
negatively.
A wolf pack in Yellowstone
National Park
In popular literature, wolf packs are often portrayed as strictly
hierarchical social structures with a breeding "alpha" pair which climbs the social ladder
through fighting, followed by subordinate "beta" wolves and a low ranking
"omega" which bears the brunt of the pack's aggression. This terminology is
based heavily on the behaviour of captive wolf packs composed of unrelated
animals, which will fight and compete against each other for status. Also, as
dispersal is impossible in captive situations, fights become more frequent than
in natural settings. In the wild, wolf packs are little more than nuclear families whose basic social unit consists
of a mated pair, followed by its offspring.
Northern wolf packs tend not to be as compact or unified as those of African wild dogs and spotted hyenas,[64]
though they are not as unstable as those of coyotes.
Southern wolves are more similar in social behaviour to coyotes and dingoes, living largely alone or in pairs.[66] The
average pack consists of 5–11 animals; 1–2 adults, 3–6 juveniles and 1–3
yearlings,
though exceptionally large packs consisting of 42 wolves are known. Wolf packs
rarely adopt other wolves into their fold, and typically kill them. In the rare
cases where strange wolves are adopted, the adoptee is almost invariably a young
animal of 1–3 years of age, while killed wolves are mostly fully grown.[68] The
adoption of a new member can be a lengthy process, and can consist of weeks of
exploratory, non-fatal attacks in order to establish whether or not the newcomer
is trustworthy.
During times of ungulate abundance (migration, calving etc.), different wolf
packs may temporarily join forces.
Wolves as young as five months and as old as five years have been recorded to
leave their packs to start their own families, though the average age is 11–24
months. Triggers for dispersal include the onset of sexual maturity and
competition within the pack for food and breeding.
Mated
pairs usually remain together for life if one of the wolves does not die. Upon
the death of one mated wolf, pairs are quickly re-established. Since males often
predominate in any given wolf population, unpaired females are a rarity. Polygamy does occur, but primarily in captive
situations. Multiple litters are rarely successful, due to infanticide by the pack's females. The
age of first breeding in wolves depends largely on environmental factors; when
food is abundant, or when wolf populations are heavily managed, wolves can rear
pups at younger ages in order to exploit the newly available resources. Captive
wolves have been known to breed as soon as they reach 9–10 months, while the
youngest recorded breeding wolves in the wild were 2 years old. Females are
capable of producing pups every year, with one litter annually being the. Incest rarely occurs, though inbreeding depression has been reported to be a
problem for wolves in Saskatchewan and
Isle
Royal
Estrus typically occurs in late winter, with
older, multiparous females entering estrus 2–3 weeks earlier than younger
females. Before the rut ensues, wolf packs will temporarily dissolve until the
end of the mating season. When
receptive, females will avert the base of their tails to one side, exposing the
vulva. During mating, the pair is locked into a
copulatory tie which may last 5–36 minutes. Because estrus in wolves only lasts
a month, the males do not abandon their mates to find other females to
inseminate as dogs do. During pregnancy, female wolves will remain in a den
located away from the peripheral zone of their territories, where violent
encounters with other packs are more likel Old
females usually whelp
in the den of their previous litter, while younger females typically den near
their birthplace. The gestation period lasts 62–75 days, with pups
usually being born in the summer period The
average litter consists of 5–6 pups. Litters of 14–17 occur 1% of the time.
Litter sizes tend to increase in areas where prey is abundant.
Wolves bear relatively large pups in small litters compared to other canid
species.Pups
are born blind and deaf, and are covered in short soft grayish-brown
fur. They weigh 300–500 grams at birth, and begin to see after 9–12 days. The
milk canines erupt after one month. Pups first leave the den after 3 weeks. At
1.5 months of age, they are agile enough to flee from danger. Mother wolves do
not leave the den for the first few weeks, relying on the fathers to provide
food for them and their young.Unlike wolf mothers, the fathers do not regurgitate the pup's food, but carry
them pieces from a kill. If the mother dies prior to the pups weaning period,
they are suckled by the pack's other females. Pups
begin to eat solid food at the age of 3–4 weeks. Pups have a fast growth rate
during their first four months of life: during this period, the pup's weight can
increase nearly 30 times.
The reproductive behaviour of introduced wolf packs in Yellowstone is unusual,
as they often have multiple breeding females who mate with lone male wolves that
encroach upon the pack territories during the mating season. These so called "Casanova wolves" are young males that, having
failed to procure mates or territories after leaving their natal pack, mate with
the daughters of already established breeding pairs from other packs. Unlike
males from established packs, Casanova wolves do not form pair bonds with the
females they mate with. Because of the great abundance of prey in Yellowstone,
female wolves there can bear multiple litters in this fashion.
Wolves use different places for their diurnal rest; places with cover are
preferred during cold, damp and windy weather, while wolves in dry, calm and
warm weather readily rest in the open. During the autumn-spring period, when
wolves are more active, they willingly lie out in the open, whatever their
location. Actual dens are usually constructed for pups during the summer period.
When building dens, females make use of natural shelters such as fissures in
rocks, cliffs overhanging riverbanks and holes thickly covered by vegetation.
Sometimes, the den is the appropriated burrow of smaller animals such as foxes,
badgers or marmots. An appropriated den is often widened and partly remade. On
rare occasions, female wolves will dig burrows themselves, which are usually
small and short with 1-3 openings.
Wolves do not line their denning places, a likely precaution against
parasites. The
den is usually constructed not more than 500 metres away from a water source.
Resting places, play areas for the pups and food remains are commonly found
around wolf dens. The odour of urine and rotting food emanating from the denning
area often attracts scavenging birds such as magpies and ravens. As there are few convenient places for
burrows, wolf dens are usually occupied by animals of the same family. Though
they mostly avoid areas within human sight, wolves have been known to nest near
domiciles,
paved roads
and railways
Wolves scent-roll to bring scents back to the
pack
Wolves are highly territorial animals, and generally establish territories
far larger than they require to survive in order to assure a steady supply of
prey. Territory size depends largely on the amount of prey available: in areas
with an abundance of prey, the territories of resident wolf packs are smaller.
Wolf packs travel constantly in search of prey, covering roughly 9% of their
territory per day (average 25 km/d or 15 mi/d). The core of their territory is
on average 35 km2 (14 sq mi), in which they
spend 50% of their time. Prey
density tends to be much higher in the territory's surrounding areas. Despite
this higher abundance of prey, wolves tend to avoid hunting in the fringes of
their territory unless desperate, due to the possibility of fatal encounters
with neighboring packs.The
size of their territory may increase when the pack's pups reach the age of 6
months, and thus have the same nutritional requirements as adults. The smallest
territory on record was held by a pack of six wolves in northeastern Minnesota,
which occupied an estimated 33 km2. The largest
was held by an Alaskan pack of ten wolves encompassing a 6,272 km2 area. In some areas, wolves may shift territories during
their prey's migration season.
Wolves defend their territories from other packs through a combination of scent marking, direct attacks and howling (see Communication). Scent marking is used for
territorial advertisement, and involves urination, defecation and ground
scratching. Scent marks are generally left every 240 metres throughout the
territory on regular travelways and junctions. Such markers can last for 2–3
weeks, and
are typically placed near rocks, boulders, trees or the skeletons of large
animals. When
scent marking and howling fail to deter strange wolf packs from entering
another's territory, violent interactions can ensue.
Territorial fights are among the principal causes of wolf mortality: one study
on wolf mortality in Minnesota and the Denali National Park and Preserve concluded that
14–65% of wolf deaths were due to predation by other wolves.In
fact, 91% of wolf fatalities occur within 3.2 km (2.0 mi) of the borders between
neighboring territories.
Because the consequences of trespassing can be fatal, such incursions are
thought to be largely due to desperation or deliberate aggressiveness.
Wolves primarily feed on medium to large sized ungulates (sometimes 10–15 times larger than
themselves[26]),
though they are not fussy eaters. Medium and small sized animals preyed on by
wolves include marmots, hares, badgers, foxes, polecats[disambiguation needed], ground squirrels, mice, hamsters, voles and other rodents, as well as insectivores. They frequently eat waterfowl (particularly during their moulting
period and winter, when their greasy and fatty meat helps wolves build up their
fat reserves) and their eggs.[94][95] When
such foods are insufficient, they will prey on lizards, snakes, frogs, rarely toads and large insects. In times of scarcity, wolves will
readily eat carrion,
visiting cattle burial grounds and slaughter houses.[94] Wolf
packs in Astrakhan
will hunt Caspian seals on the Caspian Sea coastline.[96] Some
wolf packs in Alaska and Western Canada have been observed to feed on salmon.[97] Cannibalism is not uncommon in wolves; during
harsh winters, packs often attack weak or injured wolves, and may eat the bodies
of dead pack members.[98][99][100]
However, they are not known to eat their young as coyotes sometimes do.[84] Humans are rarely, but occasionally preyed upon
(see Attacks on humans).[101][102][103][104]
Wolves will supplement their diet with fruit and vegetable matter; they
willingly eat the berries of mountain ash, lily of the valley, bilberries, blueberries and cowberry. Other fruits include nightshade, apples and pears. They readily visit melon fields during the summer months.[98]
Wolves can survive without food for long periods; two weeks without food will
not weaken a wolf's muscle activity.[35]
In Eurasia, many wolf populations are forced to subsist largely on livestock and garbage in areas with dense human activity,
though wild ungulates such as moose,[105] red deer, roe
deer and wild
boar are still important food sources in Russia and the more
mountainous regions of Eastern Europe. Other prey species include reindeer, mouflon, wisent, saiga, ibex, chamois, wild goats, fallow
deer and musk
deer.[106] The
prey animals of North American wolves have largely continued to occupy suitable
habitats with low human density, and cases of wolves subsisting largely on
garbage or livestock are exceptional. Animals commonly preyed on by North
American wolves include moose, white-tailed deer, elk, mule deer, mountain sheep and caribou.[107] In
North Africa, wolves feed on various cultivated crops and vegetables and
domestic animals.[108]
Hunting and
feeding behaviours
Although wolf packs do cooperate strategically in bringing down prey, they do
not do so as frequently or as effectively as lionesses do; unlike lions, wolves rarely remain
with their pack for more than two years, thus they have less time to learn how
to hunt cooperatively. Contrary to lion prides, food acquisition per wolf
decreases with pack size.[109]
Overall, single wolves or mated pairs typically have higher success rates in
hunting than do large packs. Single wolves have occasionally been observed to
kill large prey such as moose, bison and muskoxen unaided.[110] When
hunting, wolves will attempt to conceal themselves as they approach their prey.
With ungulate herds, they then either attempt to break up the herd, or isolate
one or two animals from it.[111] If
the targeted animal stands its ground, the wolves either ignore it, or try to
intimidate it into running.[112] When
chasing small prey, wolves will attempt to catch up with their prey as soon as
possible. With larger animals, the chase is prolonged, in order to wear the
selected prey out.[110]
Wolves usually give up chases after 1–2 km (0.62-1.3 mi), though one wolf was
recorded to chase a deer for 21 km (13 mi).[32]
Sometimes, a single wolf will distract the herd with its presence, acting as a
decoy, while its pack mates attack from
behind.[113] Wolf
packs may also set up ambush trails; Indian wolves have been observed to chase
gazelle herds through ravines where other wolves lie in wait within holes dug
prior to the hunt,[114]
while Russian wolves will set up ambushes near water
holes, sometimes using the same site repeatedly.[111] Both
Russian and North American wolves have been observed to drive prey onto crusted
ice, precipices, ravines, slopes and steep banks to slow them down.[115]
Mature wolves usually avoid attacking large prey frontally, instead focusing on
the rear and sides of the animal. They kill large prey by biting large chunks of
flesh from the soft perineum area, causing massive blood loss. Such bites can cause wounds 10–15 cm
in length, with three such bites to the perineum usually being sufficient to
bring down a large deer in optimum health.[115] When
attacking moose, they occasionally bleed it to death by biting its soft
nose.[99] With
medium-sized prey such as roe deer or sheep, northern wolves kill by biting the
throat, severing nerve tracks and the carotid artery, thus causing the animal to die
within a few seconds to a minute,[116]
while the smaller southern wolves may grab the animal by the neck and stun it by
jerking its head downward, hitting its nose on the ground.[9] When
prey is vulnerable and abundant, wolves may occasionally surplus kill. Such instances are common in
domestic animals, but rare in the wild. In the wild, surplus killing primarily
occurs during late winter or spring, when snow is unusually deep (thus impeding
the movements of prey)[117] or
during the denning period, when wolves require a ready supply of meat when
denbound.[118]
Medium-sized prey are especially vulnerable to surplus killing, as the swift
throat-biting method by which they are killed allows wolves to quickly kill one
animal and move on to another.[116]
Surplus killing may also occur when adult wolves are teaching their young to
hunt.[119]
The breeding pair typically monopolizes food in order to continue producing
pups. When food is scarce, this is done at the expense of other family members,
especially non-pups.[95][120] This
is in marked contrast to the feeding behaviours of dholes and African wild dogs, who give priority to their
pups when feeding.[121] The
breeding pair typically eats first, though as it is they who usually work the
hardest in killing prey, they may rest after a long hunt and allow the rest of
the family to eat unmolested. Once the breeding pair has finished eating, the
rest of the family will tear off pieces of the carcass and transport them to
secluded areas where they can eat in peace. Wolves typically commence feeding by
consuming the larger internal organs of their prey, such as the heart, liver, lungs and stomach lining. The kidneys and spleen are eaten once they are exposed, followed
by the muscles.[122]
Relationships with other predators
Wolf barking at a brown bear in Juraparc, Vallorbe, Vaud, Switzerland
Wolves typically dominate other canid species in areas where they both occur. In
North America, incidences of wolves killing coyotes are common, with such incidences being
especially common in winter, when coyotes feed on wolf kills. Wolves may attack
coyote den sites, digging out and killing the pups. They rarely eat the coyotes
they kill. There are no records of coyotes killing wolves, though coyotes may
chase wolves if they outnumber them.[123][124] Near
identical interactions have been observed in Eurasia between wolves and golden jackals, with the latter's numbers being
comparatively small in areas with high wolf densities.[123][125][126]
Wolves are the most important predator of raccoon
dogs, killing large numbers of them in the spring and summer
periods.[127]
Wolves also kill red, arctic and corsac
foxes, usually in disputes over carcasses. They may eat the foxes
they kill.[128][129] In
Asia, they may compete with dholes.[130]
Brown bears are encountered by wolves in both
Eurasia and North America. Generally, the outcome of such encounters depends on
context: brown bears typically prevail against wolves in disputes over
carcasses, while wolves mostly prevail against bears when defending their den
sites. Both species will kill each other's young. Wolves will eat the brown
bears they kill, while brown bears seem to only eat young wolves.[131] American black bears occur solely in the
Americas. Wolf interactions with black bears are much rarer than with brown
bears, due to differences in habitat preferences. The majority of black bear
encounters with wolves occur in the species' northern range, with no
interactions being recorded in Mexico. Wolves have been recorded on numerous
occasions to actively seek out black bears in their dens and kill them without
eating them. Unlike brown bears, black bears frequently lose against wolves in
disputes over kills.[132]
While encounters with brown and black bears appear to be common, polar
bears are rarely encountered by wolves, though there are two
records of wolf packs killing polar bear cubs.[133]
Wolves will also kill the cubs of Asian black bears.[134] When
attacking bears in daylight, wolf packs have been known to harry their quarry
and wait till nightfall before making the final assault, as wolves have better
night vision than bears.[135]
Wolves may encounter striped hyenas in Israel and Central Asia, usually in disputes over
carcasses. Hyenas feed extensively on wolf-killed carcasses
in areas where the two species interact. On a one-to-one basis, hyenas dominate
wolves, though wolf packs can drive off single hyenas.[136]
Large wolf populations limit the numbers of small to medium sized felines. Wolves encounter cougars along portions of the Rocky Mountains and adjacent mountain ranges.
Wolves and cougars typically avoid encountering each other by hunting on
different elevations. In winter however, when snow accumulation forces their
prey into valleys, interactions between the two species become more likely.
Although they rarely interact, wolves and cougars will kill each other, with
packs of the former sometimes usurping the latter's kills.[137] They
hunt steppe cats, and may pose a threat to snow
leopards.[138]
Wolves may reduce Eurasian lynx populations.[139]
Other than humans, tigers appear to be the only serious predators of
wolves.[138][140][141][142] In
areas where wolves and tigers share ranges, such as the Russian Far East, the two species typically
display a great deal of dietary overlap, resulting in intense competition. Wolf
and tiger interactions are well documented in Sikhote-Alin, which until the beginning of the
20th century, held very few wolves. It is thought by certain experts that wolf
numbers increased in the region after tigers were largely eliminated during the
Russian colonization in the late 19th and early 20th centuries. This is
corroborated by native inhabitants of the region claiming that they had no
memory of wolves inhabiting Sikohte-Alin until the 1930s, when tiger numbers
decreased. Tigers depress wolf numbers, either to the point of localized extinction or to such low numbers as to
make them a functionally insignificant component of the ecosystem. Wolves appear capable of escaping competitive exclusion from tigers only when human
persecution decreases the latter's numbers. Today wolves are considered scarce
in tiger inhabited areas, being found in scattered pockets, and usually seen
traveling as loners or in small groups. First hand accounts on interactions
between the two species indicate that tigers occasionally chase wolves from
their kills, while wolves will scavenge from tiger kills. Tigers are not known
to prey on wolves, though there are four records of tigers killing wolves
without consuming them.[143] This
competitive exclusion of wolves by tigers has been used by Russian
conservationists to convince hunters in the Far East to tolerate the big cats,
as they limit ungulate
populations less than wolves, and are effective in controlling the latter's
numbers.[144]
Body language
Postural communication in wolves is composed of a variety of facial
expressions, tail positions and piloerection.[61] Aggressive or
self assertive wolves are characterised by their slow and deliberate movements,
high body posture and raised hackles, while submissive ones carry their bodies
low, sleeken their fur and lower their ears and tail.[145] When breeding
males encounter subordinate family members, they may stare at them, standing
erect and still with their tails horizontal to their spine.[146] The pre-caudal
scent glands may play a role in expressing aggression, as combative wolves will
raise the base of their tails whilst drooping the tip, thus positioning the
scent glands at the highest point.[147]
Two forms of submissive behaviour are recognised: passive and active. Passive
submission usually occurs as a reaction to the approach of a dominant animal,
and consists of the submissive wolf lying partly on its back and allowing the
dominant wolf to sniff its anogenital area. Active submission occurs often as a
form of greeting, and involves the submissive wolf approaching another in a low
posture, and licking the other wolf's face.[148]
When wolves are together, they commonly endulge in behaviours such as nose
pushing, jaw wrestling, cheek rubbing and facial licking. The mouthing of each
other's muzzles is a friendly gesture, while clamping on the muzzle with bared
teeth is a dominance display. Dominant wolves may assert themselves by
straddling over a subordinate family member.[149] At a kill,
wolves will protect the carcass from afar from other wolves by flattening their
ears outwardly, thus indicating that they are covering something belonging to
them.[150]
Problems
listening to this file? See media
help.
Wolves howl to assemble the pack (usually before and after hunts), to pass on
an alarm (particularly at a den site), to locate each other during a storm or
unfamiliar territory and to communicate across great distances.[151] Howling
consists of a fundamental frequency which may lie between 150 and 780 Hz, and
consists of up to 12 harmonically related overtones. The pitch usually remains
constant or varies smoothly, and may change direction as many as four or five
times.[24] Wolves from
different geographic locations may howl in different fashions; the howls of
European wolves are much more protracted and melodious than those of North
American wolves, whose howls are louder and have a stronger emphasis on the
first syllable. The two are however mutually intelligible, as North American wolves have
been recorded to respond to European-style howls made by biologists.[152]
Wolf howls are generally indistinguishable from those of large dogs.[153] Male wolves
give voice through an octave,
passing to a deep bass with a stress on "O", while females produce a
modulated nasal baritone
with stress on "U". Pups almost never howl, while yearling wolves produce howls
ending in a series of dog-like yelps.[154]
Howls used for calling pack mates to a kill are long, smooth sounds similar to
the beginning of the cry of a horned
owl. When pursuing prey, they emit a higher pitched howl, vibrating
on two notes. When closing in on their prey, they emit a combination of a short
bark and a howl.[153] When howling
together, wolves harmonize rather than chorus on the same note, thus creating
the illusion of there being more wolves than there actually are.[151] Lone wolves
typically avoid howling in areas where other packs are present.[155] Wolves do not
respond to howls in rainy weather and when satiated.[154]
Other
vocalisations
Other vocalisations of wolves are usually divided into three categories:
growls, barks and whines.[156] Barking has a
fundamental frequency between 320–904 Hz,[24] and is usually
emitted by startled wolves. Wolves do not bark as loudly or continuously as dogs
do, but will bark a few times and retreat from perceived danger.[156] In captivity,
wolves may learn to bark more often if they hear dogs doing so.[157]
Growling has a fundamental frequency of 380–450 Hz,[24] and is usually
emitted during food challenges. Pups commonly growl when playing. One variation
of the howl is accompanied by a high pitched whine, which precedes a lunging
attack.[151] Whining is
associated with situations of anxiety, curiosity, inquiry and intimacy such as
greeting, feeding pups and playing.[156]
The gray wolf was once the world's most widely distributed mammal,
living north of 15°N latitude in North America and 12°N in Eurasia.[168]
Wolves tend to have difficulty adapting to human induced changes, and are often
referred to as an indicator species; a species delineating an ecoregion or indicating an environmental condition such as a disease outbreak,
pollution, species competition, or climate change. Wolves do not seem to be able
to adapt as readily to expanding civilization the way coyotes do. While human
expansion has seen an increase in the latter's numbers, it has caused a drop in
those of the former.[169]
Despite not being at risk for extinction, local populations of wolves are
still threatened. One such threat is genetic bottlenecking caused by population
fragmentation.[163] Human
populations have isolated small pockets of animals, which then suffer the
effects of inbreeding. Studies have shown that the reproduction rate in wolves
is strongly related to genetic diversity.[170]
Isolated wolf populations are greatly affected by the introduction of the
alleles of even a single additional wolf.[163]
With the exception of the Great Britain and Ireland, wolves were widespread in Europe during the 18th century. Wolves were
exterminated from all central and northern European countries during the 19th
century and the post World War II period. Remnant populations remain in Portugal, Spain, Italy, Greece and Finland, though Eurasian wolves have been recovering
naturally in several parts of Europe; recolonising France, Germany, Sweden and Norway. The largest populations now occur in eastern Europe, primarily in Romania, the Balkans and Poland.[171]
Wolf populations generally seem to be stable or increasing in most, but not
all, Bern Convention nations. Limiting factors in member
nations include a lack of acceptance of wolves (particularly in areas where they
have made a comeback) due to concerns on livestock and dog predation and
competition with hunters. Although properly regulated wolf harvests and control
have been largely accepted as compatible with maintaining wolf numbers to
economically acceptable levels, overhunting and poaching are recognised as the
main limiting factor in European wolf populations.[172]
With the exception of Israel and Saudi Arabia, there is little information available
on wolves in the Middle
East. The Arabian Peninsula is home to an estimated 300–600
wolves which, though hunted year round in all Middle Eastern countries except
Israel, are relatively stable and protected by the inaccessibility of the
northern mountains and central and northern deserts. In India, wolves are classed as endangered,
and number an estimated 800-3,000 individuals scattered among several remnant
populations. In China
and Mongolia, wolves are not protected except in
reserves.[173]
Wolves once ranged over much of North America north of Mexico City, save for parts of California. Today, their status varies by country,
state and province. Canadian and Alaskan wolves number in thousands and are in
excellent biological condition. Wolves have expanded from Canada to the northern
Rocky Mountains since the 1970s, establishing
themselves southward in Montana, Washington,
Idaho and Wyoming. In 1994, wolves from Alberta and British Columbia were captured and introduced into Yellowstone
National Park, where they had been extinct since the 1930s. A similar
introduction took place in 1998 in the Apache National Forest in Arizona.[174]
A small, isolated group of wolves on Isle Royale is believed to be suffering
from the effects of reduced genetic variability. In 1991, the population was
reduced from 50 to 12 wolves. Studies have shown that this reduction has
coincided with a 50% loss of allozyme heterozygosity.[175]
The presence of wolves in Egypt, Libya
and Ethiopia was confirmed in 2011, when a comparison was
made between the MtDNA sequences of golden jackals, Holarctic wolves (most
modern wolves are of this ancestry), the Indian wolf, and the Himalayan wolf
(which are considered older lineages than the main Holarctic wolf lineage)
revealed that North African wolves are more closely related to Indian and
Himalayan wolves than they are to golden jackals, a species which they were
associated with in the past.[176]
Diseases and
parasites
Illustration of the diseased jawbone of a young
wolf from Oreston
Because wolves travel great distances, they may play an important role in
spreading and maintaining diseases in certain areas. Infectious diseases spread
by wolves include brucellosis, tularemia, listeriosis and anthrax. Wolves may also suffer from rabies: wolves are a major host for the disease in
Russia, Iran, Afghanistan, Iraq and India.[177] Canine distemper seems to only pose a serious problem
for wolves in Canada and Alaska.[178]
Wolves also carry the Canine coronavirus, with infections being most
prevalent in winter months.[179]
However, gray wolf populations are remarkably resilient against disease
outbreaks. Usually, a wolf displaying the first symptoms of disease will leave
its pack, thus preventing the sickness from spreading to its pack mates. Wolves
in the former Soviet Union have been recorded to carry over 50 different
parasite species.[177] Ticks
carried by wolves include Ixodes ricinus, Dermacentor pictus and Sarcoptes scabiei (or mange mite). Unlike foxes, wolves rarely develop full
blown mange. Other ectoparasites include biting lice, sucking lice and the fleas Pulex
irritans and Ctenocephalides canis. Endoparasites include nematodes such as Toxascaris leonina and T.
canis.[180] Wolves are also
carriers of Trichinella spiralis, the prelevance of which is
significantly related to age.[181]
Other endoparasites include cestodes such as Taenia pisiformis, T. hydatigena, Echinococcus
granulosus, Mesocestoidea lineatus, Dioctophyme renale and the adult phase of
Multiceps multiceps.[180]
Wolves may carry Neospora caninum, which is of particular concern
to farmers, as the disease can be spread to livestock; infected animals being
three to thirteen times more likely to abort than those not infected.[182] Wolves
suffering from tapeworms may deliberately forego eating fresh meat
in favour of putrified flesh, in order to rid themselves of the parasites.[183]
Wolves are highly resistant to radiation poisoning, as evidenced by wolves thriving
in the zone of alienation north of Chernobyl,
despite feeding extensively on highly radioactive ungulates.[
2/7/11 Groundhog
The groundhog (Marmota monax), also known as a woodchuck, or in some areas as a land-beaver, is a rodent of the family Sciuridae, belonging to the group of large ground squirrels known as marmots. Other marmots, such as the yellow-bellied and hoary marmots, live in rocky and mountainous areas, but the woodchuck is a lowland creature. It is widely distributed in North America and common in the northeastern and central United States. Groundhogs are found as far north as Alaska, with their habitat extending southeast to Alabama.
Description
The groundhog is the largest sciurid in its geographical range, typically measuring 40 to 65 cm (16 to 26 in) long (including a 15 cm (6 in) tail) and weighing 2 to 4 kg (4 to 9 lb). In areas with fewer natural predators and large amounts of alfalfa, groundhogs can grow to 80 cm (30 in) and 14 kg (31 lb). Groundhogs are well adapted for digging, with short but powerful limbs and curved, thick claws. Unlike other sciurids, the groundhog's spine is curved, more like that of a mole, and the tail is comparably shorter as well – only about one-fourth of body length. Suited to their temperate habitat, groundhogs are covered with two coats of fur: a dense grey undercoat and a longer coat of banded guard hairs that gives the groundhog its distinctive "frosted" appearance.
Survival
Groundhogs usually live from two to three years, but can live up to six years in the wild. In captivity, groundhogs can exceed this limit; by example, the 22-year-old Wiarton Willie may indicate the maximum lifespan. Common predators for groundhogs include wolves, coyotes, foxes, bobcats, bears, large hawks, owls, and dogs. Young groundhogs are often at risk for predation by snakes, which easily enter the burrow.
Diet
A groundhog feeding.Mostly herbivorous, groundhogs primarily eat wild grasses and other vegetation, and berries and agricultural crops when available.[3] Groundhogs also eat grubs, grasshoppers, insects, snails and other small animals, but are not as omnivorous as many other sciuridae. Like squirrels they also have been observed sitting up eating nuts such as shagbark hickory but unlike squirrels do not bury them for future use.
Burrows
Groundhogs are excellent burrowers, using burrows for sleeping, rearing young, and hibernating. The average groundhog has been estimated to move approximately 1 m3 (35 cu ft), or 320 kg (710 lb), of dirt when digging a burrow. Though groundhogs are the most solitary of the marmots, several individuals may occupy the same burrow. Groundhog burrows usually have two to five entrances, providing groundhogs their primary means of escape from predators. Burrows are particularly large, with up to 14 metres (46 ft) of tunnels buried up to 1.5 metres (5 ft) underground, and can pose a serious threat to agricultural and residential development by damaging farm machinery and even undermining building foundations.[4]
Hibernation
Groundhogs are one of the few species that enter into true hibernation, and often build a separate "winter burrow" for this purpose. This burrow is usually in a wooded or brushy area and is dug below the frost line and remains at a stable temperature well above freezing during the winter months. In most areas, groundhogs hibernate from October to March or April, but in more temperate areas, they may hibernate as little as 3 months.[5] To survive the winter, they are at their maximum weight shortly before entering hibernation. They emerge from hibernation with some remaining body fat to live on until the warmer spring weather produces abundant plant materials for food.
Groundhogs are able to climb trees to escape.Despite their heavy-bodied appearance, groundhogs are accomplished swimmers and excellent tree climbers when escaping predators or when they want to survey their surroundings.[6] They prefer to retreat to their burrows when threatened; if the burrow is invaded, the groundhog tenaciously defends itself with its two large incisors and front claws. Groundhogs are generally agonistic and territorial among their own species, and may skirmish to establish dominance.[3]
A nearly motionless individual, alert to danger, will whistle when alarmed to warn other groundhogs.Outside their burrow, individuals are alert when not actively feeding. It is common to see one or more nearly-motionless individuals standing erect on their hind feet watching for danger. When alarmed, they use a high-pitched whistle to warn the rest of the colony, hence the name "whistle-pig".[4][7] Groundhogs may squeal when fighting, seriously injured, or caught by an enemy.[7] Other sounds groundhogs may make are low barks and a sound produced by grinding their teeth.[7]
Reproduction
Usually groundhogs breed in their second year, but a small proportion may breed in their first. The breeding season extends from early March to mid- or late April, after hibernation. A mated pair remains in the same den throughout the 31–32 day[8] gestation period. As birth of the young approaches in April or May, the male leaves the den. One litter is produced annually, usually containing 2–6 blind, hairless and helpless young. Young groundhogs are weaned and ready to seek their own dens at five to six weeks of age.
Range
The groundhog prefers open country and the edges of woodland, and it is rarely far from a burrow entrance. Since the clearing of forests provided it with much more suitable habitat, the groundhog population is probably higher now than it was before the arrival of European settlers in North America. Groundhogs are often hunted for sport, which tends to control their numbers. However, their ability to reproduce quickly has tended to mitigate the depopulating effects of sport hunting.[4] As a consequence, the groundhog is a familiar animal to many people in the United States and Canada.
Description
The groundhog is the largest sciurid in its geographical range, typically measuring 40 to 65 cm (16 to 26 in) long (including a 15 cm (6 in) tail) and weighing 2 to 4 kg (4 to 9 lb). In areas with fewer natural predators and large amounts of alfalfa, groundhogs can grow to 80 cm (30 in) and 14 kg (31 lb). Groundhogs are well adapted for digging, with short but powerful limbs and curved, thick claws. Unlike other sciurids, the groundhog's spine is curved, more like that of a mole, and the tail is comparably shorter as well – only about one-fourth of body length. Suited to their temperate habitat, groundhogs are covered with two coats of fur: a dense grey undercoat and a longer coat of banded guard hairs that gives the groundhog its distinctive "frosted" appearance.
Survival
Groundhogs usually live from two to three years, but can live up to six years in the wild. In captivity, groundhogs can exceed this limit; by example, the 22-year-old Wiarton Willie may indicate the maximum lifespan. Common predators for groundhogs include wolves, coyotes, foxes, bobcats, bears, large hawks, owls, and dogs. Young groundhogs are often at risk for predation by snakes, which easily enter the burrow.
Diet
A groundhog feeding.Mostly herbivorous, groundhogs primarily eat wild grasses and other vegetation, and berries and agricultural crops when available.[3] Groundhogs also eat grubs, grasshoppers, insects, snails and other small animals, but are not as omnivorous as many other sciuridae. Like squirrels they also have been observed sitting up eating nuts such as shagbark hickory but unlike squirrels do not bury them for future use.
Burrows
Groundhogs are excellent burrowers, using burrows for sleeping, rearing young, and hibernating. The average groundhog has been estimated to move approximately 1 m3 (35 cu ft), or 320 kg (710 lb), of dirt when digging a burrow. Though groundhogs are the most solitary of the marmots, several individuals may occupy the same burrow. Groundhog burrows usually have two to five entrances, providing groundhogs their primary means of escape from predators. Burrows are particularly large, with up to 14 metres (46 ft) of tunnels buried up to 1.5 metres (5 ft) underground, and can pose a serious threat to agricultural and residential development by damaging farm machinery and even undermining building foundations.[4]
Hibernation
Groundhogs are one of the few species that enter into true hibernation, and often build a separate "winter burrow" for this purpose. This burrow is usually in a wooded or brushy area and is dug below the frost line and remains at a stable temperature well above freezing during the winter months. In most areas, groundhogs hibernate from October to March or April, but in more temperate areas, they may hibernate as little as 3 months.[5] To survive the winter, they are at their maximum weight shortly before entering hibernation. They emerge from hibernation with some remaining body fat to live on until the warmer spring weather produces abundant plant materials for food.
Groundhogs are able to climb trees to escape.Despite their heavy-bodied appearance, groundhogs are accomplished swimmers and excellent tree climbers when escaping predators or when they want to survey their surroundings.[6] They prefer to retreat to their burrows when threatened; if the burrow is invaded, the groundhog tenaciously defends itself with its two large incisors and front claws. Groundhogs are generally agonistic and territorial among their own species, and may skirmish to establish dominance.[3]
A nearly motionless individual, alert to danger, will whistle when alarmed to warn other groundhogs.Outside their burrow, individuals are alert when not actively feeding. It is common to see one or more nearly-motionless individuals standing erect on their hind feet watching for danger. When alarmed, they use a high-pitched whistle to warn the rest of the colony, hence the name "whistle-pig".[4][7] Groundhogs may squeal when fighting, seriously injured, or caught by an enemy.[7] Other sounds groundhogs may make are low barks and a sound produced by grinding their teeth.[7]
Reproduction
Usually groundhogs breed in their second year, but a small proportion may breed in their first. The breeding season extends from early March to mid- or late April, after hibernation. A mated pair remains in the same den throughout the 31–32 day[8] gestation period. As birth of the young approaches in April or May, the male leaves the den. One litter is produced annually, usually containing 2–6 blind, hairless and helpless young. Young groundhogs are weaned and ready to seek their own dens at five to six weeks of age.
Range
The groundhog prefers open country and the edges of woodland, and it is rarely far from a burrow entrance. Since the clearing of forests provided it with much more suitable habitat, the groundhog population is probably higher now than it was before the arrival of European settlers in North America. Groundhogs are often hunted for sport, which tends to control their numbers. However, their ability to reproduce quickly has tended to mitigate the depopulating effects of sport hunting.[4] As a consequence, the groundhog is a familiar animal to many people in the United States and Canada.
1/3/11 Penguin
Penguins (order Sphenisciformes, family Spheniscidae) are a group of aquatic, flightless birds living almost exclusively in the southern hemisphere, especially in Antarctica. Highly adapted for life in the water, penguins have countershaded dark and white plumage, and their wings have become flippers. Most penguins feed on krill, fish, squid, and other forms of sealife caught while swimming underwater. They spend about half of their lives on land and half in the oceans.
Although all penguin species are native to the southern hemisphere, they are not found only in cold climates, such as Antarctica. In fact, only a few species of penguin live so far south. Several species are found in the temperate zone, and one species, the Galápagos Penguin, lives near the equator.
The largest living species is the Emperor Penguin (Aptenodytes forsteri): adults average about 1.1 m (3 ft 7 in) tall and weigh 35 kg (75 lb) or more. The smallest penguin species is the Little Blue Penguin (Eudyptula minor), also known as the Fairy Penguin, which stands around 40 cm tall (16 in) and weighs 1 kg (2.2 lb). Among extant penguins, larger penguins inhabit colder regions, while smaller penguins are generally found in temperate or even tropical climates (see also Bergmann's Rule). Some prehistoric species attained enormous sizes, becoming as tall or as heavy as an adult human. These were not restricted to Antarctic regions; on the contrary, subantarctic regions harboured high diversity, and at least one giant penguin occurred in a region not quite 2,000 km south of the equator 35 mya, in a climate decidedly warmer than today.
Contents[hide]
Some dictionaries suggest a derivation from Welsh pen "head" and gwyn "white", including the Oxford English Dictionary,[4] the American Heritage Dictionary,[5] the Century Dictionary[6] and Merriam-Webster,[7] on the basis that the name was originally applied to the great auk, which had white spots in front of its eyes (although its head was black).
An alternative etymology, found in a few English dictionaries, links the word to Latin pinguis "fat", from its perceived appearance. This etymology would be improbable if "penguin" were found to have been originally applied to the great auk, as some sources suggest.[2][4][6]
A third theory states that the word is an alteration of “pen-wing”, with reference to the rudimentary wings of great auks. This has been criticised for the unexplained nature of the alteration of the word.[6]
Systematics and evolution Living species and recent extinctions Emperor Penguins (Aptenodytes forsteri), the largest living species. Adélie Penguin (Pygoscelis adeliae) feeding young. Like its relatives, a neatly bi-coloured species with a head marking. Magellanic Penguins (Spheniscus magellanicus). The closed neck collar denotes this species. Closeup of Southern Rockhopper Penguin (Eudyptes chrysocome). The number of extant penguin species is debated. Depending on which authority is followed, penguin biodiversity varies between 17 and 20 living species, all in the subfamily Spheniscinae. Some sources consider the White-flippered Penguin a separate Eudyptula species, while others treat it as a subspecies of the Little Penguin;[8][9] the actual situation seems to be more complicated.[10] Similarly, it is still unclear whether the Royal Penguin is merely a color morph of the Macaroni penguin. The status of the Rockhopper penguins is also unclear.
Updated after Marples (1962), Acosta Hospitaleche (2004), and Ksepka et al. (2006).
Subfamily Spheniscinae – Modern penguins
Taxonomy Some recent sources[15] apply the phylogenetic taxon Spheniscidae to what here is referred to as Spheniscinae. Furthermore, they restrict the phylogenetic taxon Sphenisciformes to flightless taxa, and establish the phylogenetic taxon Pansphenisciformes as equivalent to the Linnean taxon Sphenisciformes,[16] i.e., including any flying basal "proto-penguins" to be discovered eventually. Given that neither the relationships of the penguin subfamilies to each other nor the placement of the penguins in the avian phylogeny is presently resolved, this is confusing, so the established Linnean system is thus followed here.
Evolution The evolutionary history of penguins is well-researched and represents a showcase of evolutionary biogeography; though as penguin bones of any one species vary much in size and few good specimens are known, the alpha taxonomy of many prehistoric forms still leaves much to be desired. Some seminal articles about penguin prehistory have been published since 2005,[17][18][19][20] the evolution of the living genera can be considered resolved by now.
The basal penguins lived around the time of the Cretaceous–Tertiary extinction event somewhere in the general area of (southern) New Zealand and Byrd Land, Antarctica.[19] Due to plate tectonics, these areas were at that time less than 1,500 kilometers (932 mi) apart rather than the 4,000 kilometers (2,485 mi) of today. The most recent common ancestor of penguins and their sister clade can be roughly dated to the Campanian–Maastrichtian boundary, around 70–68 mya.[18][20][21] What can be said as certainly as possible in the absence of direct (i.e., fossil) evidence is that by the end of the Cretaceous, the penguin lineage must have been evolutionarily well distinct, though much less so morphologically; it is fairly likely that they were not yet entirely flightless at that time, as flightless birds have generally low resilience to the breakdown of trophic webs that follows the initial phase of mass extinctions because of their below-average dispersal capabilities (see also Flightless Cormorant).[citation needed]
The basal fossils The oldest known fossil penguin species is Waimanu manneringi, which lived in the early Paleocene epoch of New Zealand, or about 62 mya.[20] While they were not as well-adapted to aquatic life as modern penguins, Waimanu were generally loon-like birds but already flightless, with short wings adapted for deep diving.[citation needed] They swam on the surface using mainly their feet, but the wings were – as opposed to most other diving birds, living and extinct – already adapting to underwater locomotion.[citation needed]
Perudyptes from northern Peru was dated to 42 mya. An unnamed fossil from Argentina proves that by the Bartonian (Middle Eocene), some 39–38 mya,[22] primitive penguins had spread to South America and were in the process of expanding into Atlantic waters.[16]
Palaeeudyptines During the Late Eocene and the Early Oligocene (40–30 mya), some lineages of gigantic penguins existed. Nordenskjoeld's Giant Penguin was the tallest, growing nearly 1.80 meters (6 ft) tall. The New Zealand Giant Penguin was probably the heaviest, weighing 80 kg or more. Both were found on New Zealand, the former also in the Antarctic farther eastwards.
Traditionally, most extinct species of penguins, giant or small, had been placed in the paraphyletic subfamily called Palaeeudyptinae. More recently, with new taxa being discovered and placed in the phylogeny if possible, it is becoming accepted that there were at least two major extinct lineages. One or two closely related ones occurred in Patagonia, and at least one other—which is or includes the paleeudyptines as recognized today – occurred on most Antarctic and subantarctic coasts.
But size plasticity seems to have been great at this initial stage of penguin radiation: on Seymour Island, Antarctica, for example, around 10 known species of penguins ranging in size from medium to huge apparently coexisted some 35 mya during the Priabonian (Late Eocene).[23] It is not even known whether the gigantic palaeeudyptines constitute a monophyletic lineage, or whether gigantism was evolved independently in a much restricted Palaeeudyptinae and the Anthropornithinae – whether they were considered valid, or whether there was a wide size range present in the Palaeeudyptinae as delimited as usually done these days (i.e., including Anthropornis nordenskjoeldi).[19] The oldest well-described giant penguin, the 5-foot-tall Icadyptes salasi, actually occurred as far north as northern Peru about 36 mya.
In any case, the gigantic penguins had disappeared by the end of the Paleogene, around 25 mya. Their decline and disappearance coincided with the spread of the Squalodontoidea and other primitive, fish-eating toothed whales, which certainly competed with them for food, and were ultimately more successful.[18] A new lineage, the Paraptenodytes, which includes smaller but decidedly stout-legged forms, had already arisen in southernmost South America by that time. The early Neogene saw the emergence of yet another morphotype in the same area, the similarly sized but more gracile Palaeospheniscinae, as well as the radiation that gave rise to the penguin biodiversity of our time.
Origin and systematics of modern penguins Modern penguins consititute two undisputed clades and another two more basal genera with more ambiguous relationships.[17] The origin of the Spheniscinae lies probably in the latest Paleogene, and geographically it must have been much the same as the general area in which the order evolved: the oceans between the Australia-New Zealand region and the Antarctic.[18] Presumedly diverging from other penguins around 40 mya,[18] it seems that the Spheniscinae were for quite some time limited to their ancestral area, as the well-researched deposits of the Antarctic Peninsula and Patagonia have not yielded Paleogene fossils of the subfamily. Also, the earliest spheniscine lineages are those with the most southern distribution.
The genus Aptenodytes appears to be the basalmost divergence among living penguins[24][25] they have bright yellow-orange neck, breast, and bill patches; incubate by placing their eggs on their feet, and when they hatch the chicks are almost naked. This genus has a distribution centered on the Antarctic coasts and barely extends to some subantarctic islands today.
Pygoscelis contains species with a fairly simple black-and-white head pattern; their distribution is intermediate, centered on Antarctic coasts but extending somewhat northwards from there. In external morphology, these apparently still resemble the common ancestor of the Spheniscinae, as Aptenodytes' autapomorphies are in most cases fairly pronounced adaptations related to that genus' extreme habitat conditions. As the former genus, Pygoscelis seems to have diverged during the Bartonian,[26] but the range expansion and radiation that led to the present-day diversity probably did not occur until much later; around the Burdigalian stage of the Early Miocene, roughly 20–15 mya.[18]
The genera Spheniscus and Eudyptula contain species with a mostly subantarctic distribution centered on South America; some, however, range quite far northwards. They all lack carotenoid coloration, and the former genus has a conspicuous banded head pattern; they are unique among living penguins by nesting in burrows. This group probably radiated eastwards with the Antarctic Circumpolar Current out of the ancestral range of modern penguins throughout the Chattian (Late Oligocene), starting approximately 28 mya.[18] While the two genera separated during this time, the present-day diversity is the result of a Pliocene radiation, taking place some 4–2 mya.[18]
The Megadyptes–Eudyptes clade occurs at similar latitudes (though not as far north as the Galapagos Penguin), has its highest diversity in the New Zealand region, and represent a westward dispersal. They are characterized by hairy yellow ornamental head feathers; their bills are at least partly red. These two genera diverged apparently in the Middle Miocene (Langhian, roughly 15–14 mya), but again, the living species of Eudyptes are the product of a later radiation, stretching from about the late Tortonian (Late Miocene, 8 mya) to the end of the Pliocene.[18]
The geographical and temporal pattern or spheniscine evolution corresponds closely to two episodes of global cooling documented in the paleoclimatic record.[18] The emergence of the subantarctic lineage at the end of the Bartonian corresponds with the onset of the slow period of cooling that eventually led to the ice ages some 35 million years later. With habitat on the Antarctic coasts declining, by the Priabonian more hospitable conditions for most penguins existed in the subantarctic regions rather than in Antarctica itself.[27] Notably, the cold Antarctic Circumpolar Current also started as a continuous circumpolar flow only around 30 mya, on the one hand forcing the Antarctic cooling, and on the other facilitating the eastward expansion of Spheniscus to South America and eventually beyond.[18] Despite this, there is no fossil evidence to support the idea a crown radiation from the antarctic continent in the Paleogene.[27]
Later, an interspersed period of slight warming was ended by the Middle Miocene Climate Transition, a sharp drop in global average temperature from 14–12 mya, and similar abrupt cooling events followed at 8 mya and 4 mya; by the end of the Tortonian, the Antarctic ice sheet was already much like today in volume and extent. The emergence of most of today's subantarctic penguin species almost certainly was caused by this sequence of Neogene climate shifts.
Relationship to other bird orders Penguin ancestry beyond Waimanu remains unknown and not well-resolved by molecular or morphological analyses. The latter tend to be confounded by the strong adaptive autapomorphies of the Sphenisciformes; a sometimes perceived fairly close relationship between penguins and grebes is almost certainly an error based on both groups' strong diving adaptations, which are homoplasies. On the other hand, different DNA sequence datasets do not agree in detail with each other either.
Humboldt Penguins in an aquarium. The penguin is an accomplished swimmer, having flippers instead of wings. What seems clear is that penguins belong to a clade of Neoaves (living birds except paleognaths and fowl) that comprises what is sometimes called "higher waterbirds" to distinguish them from the more ancient waterfowl. This group contains such birds as storks, rails, and the seabirds, with the possible exception of the Charadriiformes.[28]
Inside this group, penguin relationships are far less clear. Depending on the analysis and dataset, a close relationship to Ciconiiformes[20] or to Procellariiformes[18] has been suggested. Some think the penguin-like plotopterids (usually considered relatives of anhingas and cormorants) may actually be a sister group of the penguins, and that penguins may have ultimately shared a common ancestor with the Pelecaniformes and consequently would have to be included in that order, or that the plotopterids were not as close to other pelecaniforms as generally assumed, which would necessitate splitting the traditional Pelecaniformes in three.[29]
Anatomy and physiology Orcas swim by an iceberg with Adelie Penguins in the Ross Sea, Antarctica. The Drygalski ice tongue is visible in the background. Penguins are superbly adapted to aquatic life. Their vestigial wings have become flippers, useless for flight in the air. In the water, however, penguins are astonishingly agile. Penguins' swimming looks very similar to bird's flight in the air.[30] Within the smooth plumage a layer of air is preserved, ensuring buoyancy. The air layer also helps insulate the birds in cold waters. On land, penguins use their tails and wings to maintain balance for their upright stance.
All penguins are countershaded for camouflage – that is, they have black backs and wings with white fronts.[31] A predator looking up from below (such as an orca or a leopard seal) has difficulty distinguishing between a white penguin belly and the reflective water surface. The dark plumage on their backs camouflages them from above.
Diving penguins reach 6 to 12 km/h (3.7 to 7.5 mph), though there are reports of velocities of 27 km/h (17 mph) (which are more realistic in the case of startled flight)[citation needed]. The small penguins do not usually dive deep; they catch their prey near the surface in dives that normally last only one or two minutes. Larger penguins can dive deep in case of need. Dives of the large Emperor Penguin have been recorded reaching a depth of 565 m (1,870 ft) for up to 22 minutes.
Penguins either waddle on their feet or slide on their bellies across the snow, a movement called "tobogganing", which conserves energy while moving quickly. They also jump with both feet together if they want to move more quickly or cross steep or rocky terrain.
Penguins have an average sense of hearing for birds;[32] this is used by parents and chicks to locate one another in crowded colonies.[33] Their eyes are adapted for underwater vision, and are their primary means of locating prey and avoiding predators; in air it has been suggested that they are nearsighted, although research has not supported this hypothesis.[34]
Gentoo Penguin swimming underwater at Nagasaki Penguin Aquarium. Penguins have a thick layer of insulating feathers that keeps them warm in water (heat loss in water is much greater than in air). The Emperor Penguin (the largest penguin) has the largest body mass of all penguins, which further reduces relative surface area and heat loss. They also are able to control blood flow to their extremities, reducing the amount of blood that gets cold, but still keeping the extremities from freezing. In the extreme cold of the Antarctic winter, the females are at sea fishing for food leaving the males to brave the weather by themselves. They often huddle together to keep warm and rotate positions to make sure that each penguin gets a turn in the center of the heat pack.
They can drink salt water because their supraorbital gland filters excess salt from the bloodstream.[35][36][37] The salt is excreted in a concentrated fluid from the nasal passages.
The Auk of the Northern Hemisphere is superficially similar to penguins. They are not related to the penguins at all, but considered by some[who?] to be a product of moderate convergent evolution.[38]
Isabelline penguins Isabelline Adélie Penguin on Gourdin Island. Perhaps one in 50,000 penguins (of most species) are born with brown rather than black plumage. These are called isabelline penguins, possibly in reference to the legend that the archduchess Isabella of Austria vowed not to change her undergarments until her husband united the northern and southern Low Countries by taking the city of Ostend—which took three years to accomplish.[39] Isabellinism is different from albinism. Isabelline penguins tend to live shorter lives than normal penguins, as they are not well-camouflaged against the deep, and are often passed over as mates.
Distribution and habitat Although all penguin species are native to the southern hemisphere, they are not found only in cold climates, such as Antarctica. In fact, only a few species of penguin actually live so far south. At least 10[verification needed] species live in the temperate zone; one, the Galápagos Penguin, lives as far north as the Galápagos Islands, but this is only made possible by the cold, rich waters of the Antarctic Humboldt Current that flows around these islands.[40]
Several authors have suggested that penguins are a good example of Bergmann's Rule [41][42] where larger bodied populations live at higher latitudes than smaller bodied populations. There is some disagreement about this, and several other authors have noted that there are fossil penguin species that contradict this hypothesis and that ocean currents and upwellings are likely to have had a greater effect on species diversity than latitude alone.[43][44]
Major populations of penguins are found in: Antarctica, Australia, New Zealand, South America, and South Africa.[45][46]
Behaviour Chinstrap Penguins in Antarctica. Breeding Penguins for the most part breed in large colonies, the exceptions being the Yellow-eyed and Fiordland species; these colonies may range in size from as few as a 100 pairs for Gentoo Penguins, to several hundred thousand in the case of King, Macaroni and Chinstrap Penguins.[47] Living in colonies results in a high level of social interaction between birds, which has led to a large repertoire of visual as well as vocal displays in all penguin species.[48] Agonistic displays are those intended to confront or drive off, or alternately appease and avoid conflict with, other individuals.[48]
Penguins form monogamous pairs for a breeding season, though the rate the same pair recouples varies drastically. Most penguins lay two eggs in a clutch, although the two largest species, the Emperor and the King Penguins, lay only one.[49] With the exception of the Emperor Penguin, all penguins share the incubation duties.[50] These incubation shifts can last days and even weeks as one member of the pair feeds at sea.
Penguins generally only lay one brood; the exception is the Little Penguin, which can raise two or three broods in a season.[51]
Penguin eggs are smaller than any other bird species when compared proportionally to the weight of the parent birds; at 52 g (2 oz), the Little Penguin egg is 4.7% of its mothers' weight, and the 450 g (1 lb) Emperor Penguin egg is 2.3%.[49] The relatively thick shell forms between 10 and 16 % of the weight of a penguin egg, presumably to minimise risk of breakage in an adverse nesting environment. The yolk, too, is large, and comprises 22–31 % of the egg. Some yolk often remains when a chick is born, and is thought to help sustain it if parents are delayed in returning with food.[52]
When mothers lose a chick, they sometimes attempt to "steal" another mother's chick, usually unsuccessfully as other females in the vicinity assist the defending mother in keeping her chick.[citation needed] In some species, such as Emperor Penguins, young penguins assemble in large groups called crèches.
Penguins and humans Cook on the Endurance preparing a penguin for consumption Penguins seem to have no special fear of humans, and have approached groups of explorers without hesitation. This is probably because penguins have no land predators in Antarctica or the nearby offshore islands. Instead, penguins are at risk at sea from predators such as the leopard seal. Typically, penguins do not approach closer than about 3 meters (10 ft) at which point they become nervous. This is also the distance that Antarctic tourists are told to keep from penguins (tourists are not supposed to approach closer than 3 meters, but are not expected to withdraw if the penguins come closer).
In popular culture A penguin encounters a human during Antarctic summer. Tux the Linux kernel mascot. Main article: Penguins in popular culture Penguins are popular around the world, primarily for their unusually upright, waddling gait and (compared to other birds) lack of fear of humans. Their striking black-and-white plumage is often likened to a tuxedo suit. Mistakenly, some artists and writers have penguins based at the North Pole. This is incorrect, as there are almost no wild penguins in the northern hemisphere, except the small group on the northernmost of the Galápagos. The cartoon series Chilly Willy helped perpetuate this myth, as the title penguin would interact with northern-hemisphere species such as polar bears and walruses.
Penguins have been the subject of many books and films such as Happy Feet and Surf's Up, both CGI films; March of the Penguins, a documentary based on the migration process of the Emperor Penguin; and a parody titled Farce of the Penguins. Mr. Popper's Penguins is a children's book written by Richard & Florence Atwater; it was named a Newbery Honor Book in 1939. Penguins have also found their way into a number of cartoons and television dramas; perhaps the most notable of these is Pingu, created by Silvio Mazzola in 1986 and covering more than 100 short episodes. Entertainment Weekly put it on its end-of-the-decade, "best-of" list, saying, "Whether they were walking (March of the Penguins), dancing (Happy Feet), or hanging ten (Surf's Up), these oddly adorable birds took flight at the box office all decade long."[53]
The tendency of penguins to form large groups feeds the stereotype that they all look exactly alike, a popular notion exploited by cartoonists such as Gary Larson.
Penguins featured regularly in the cartoons of UK cartoonist Steve Bell in his strip in The Guardian Newspaper, particularly during and following the Falklands War.
In the mid-2000s, penguins became one of the most publicized species of animals that form lasting homosexual couples. A children's book, And Tango Makes Three, was written about one such penguin family in the New York Zoo.
Petite creatures, they are found inhabiting mainly the country of Antarctica and might also be seen in the cold costal areas of South America, New Zealand, Australia and South Africa. They are basically aquatic birds, which can swim but cannot fly. Penguins have white undersides and a dark upper side (usually black or dark brown). They are great swimmers and on land, they either waddle on their feet or slide on their bellies. Want to know more about penguins? Read on further and get some very interesting facts and information on the adorable creatures. Facts about Penguin
Although all penguin species are native to the southern hemisphere, they are not found only in cold climates, such as Antarctica. In fact, only a few species of penguin live so far south. Several species are found in the temperate zone, and one species, the Galápagos Penguin, lives near the equator.
The largest living species is the Emperor Penguin (Aptenodytes forsteri): adults average about 1.1 m (3 ft 7 in) tall and weigh 35 kg (75 lb) or more. The smallest penguin species is the Little Blue Penguin (Eudyptula minor), also known as the Fairy Penguin, which stands around 40 cm tall (16 in) and weighs 1 kg (2.2 lb). Among extant penguins, larger penguins inhabit colder regions, while smaller penguins are generally found in temperate or even tropical climates (see also Bergmann's Rule). Some prehistoric species attained enormous sizes, becoming as tall or as heavy as an adult human. These were not restricted to Antarctic regions; on the contrary, subantarctic regions harboured high diversity, and at least one giant penguin occurred in a region not quite 2,000 km south of the equator 35 mya, in a climate decidedly warmer than today.
Contents[hide]
- 1 Etymology
- 2 Systematics and evolution
- 3 Anatomy and physiology
- 4 Distribution and habitat
- 5 Behaviour
- 6 Penguins and humans
- 7 References
- 8 External links
Some dictionaries suggest a derivation from Welsh pen "head" and gwyn "white", including the Oxford English Dictionary,[4] the American Heritage Dictionary,[5] the Century Dictionary[6] and Merriam-Webster,[7] on the basis that the name was originally applied to the great auk, which had white spots in front of its eyes (although its head was black).
An alternative etymology, found in a few English dictionaries, links the word to Latin pinguis "fat", from its perceived appearance. This etymology would be improbable if "penguin" were found to have been originally applied to the great auk, as some sources suggest.[2][4][6]
A third theory states that the word is an alteration of “pen-wing”, with reference to the rudimentary wings of great auks. This has been criticised for the unexplained nature of the alteration of the word.[6]
Systematics and evolution Living species and recent extinctions Emperor Penguins (Aptenodytes forsteri), the largest living species. Adélie Penguin (Pygoscelis adeliae) feeding young. Like its relatives, a neatly bi-coloured species with a head marking. Magellanic Penguins (Spheniscus magellanicus). The closed neck collar denotes this species. Closeup of Southern Rockhopper Penguin (Eudyptes chrysocome). The number of extant penguin species is debated. Depending on which authority is followed, penguin biodiversity varies between 17 and 20 living species, all in the subfamily Spheniscinae. Some sources consider the White-flippered Penguin a separate Eudyptula species, while others treat it as a subspecies of the Little Penguin;[8][9] the actual situation seems to be more complicated.[10] Similarly, it is still unclear whether the Royal Penguin is merely a color morph of the Macaroni penguin. The status of the Rockhopper penguins is also unclear.
Updated after Marples (1962), Acosta Hospitaleche (2004), and Ksepka et al. (2006).
Subfamily Spheniscinae – Modern penguins
- Aptenodytes – Great penguins
- King Penguin, Aptenodytes patagonicus
- Emperor Penguin, Aptenodytes forsteri
- Pygoscelis – Brush-tailed penguins
- Adélie Penguin, Pygoscelis adeliae
- Chinstrap Penguin, Pygoscelis antarctica
- Gentoo Penguin, Pygoscelis papua
- Eudyptula – Little penguins
- Little Blue Penguin, Eudyptula minor
- White-flippered Penguin, Eudyptula albosignata (provisional)
- Spheniscus – Banded penguins
- Magellanic Penguin, Spheniscus magellanicus
- Humboldt Penguin, Spheniscus humboldti
- Galapagos Penguin, Spheniscus mendiculus
- African Penguin, Spheniscus demersus
- Megadyptes
- Yellow-eyed Penguin, Megadyptes antipodes
- Waitaha Penguin, Megadyptes waitaha (extinct)
- Eudyptes – Crested penguins
- Fiordland Penguin, Eudyptes pachyrynchus
- Snares Penguin, Eudyptes robustus
- Erect-crested Penguin, Eudyptes sclateri
- Western Rockhopper Penguin, Eudyptes chrysocome
- Eastern Rockhopper Penguin, Eudyptes filholi
- Northern Rockhopper Penguin, Eudyptes moseleyi
- Royal Penguin, Eudyptes schlegeli (disputed)
- Macaroni Penguin, Eudyptes chrysolophus
- Chatham Islands Penguin, Eudyptes sp. (extinct)
- Basal and unresolved taxa (all fossil)
- Waimanu – basal (Middle-Late Paleocene)
- Perudyptes (Middle Eocene of Atacama Desert, Peru) – basal?
- Spheniscidae gen. et sp. indet. CADIC P 21 (Leticia Middle Eocene of Punta Torcida, Argentina)[11]
- Delphinornis (Middle/Late Eocene? – Early Oligocene of Seymour Island, Antarctica) – Palaeeudyptinae, basal, new subfamily 1?
- Archaeospheniscus (Middle/Late Eocene – Late Oligocene) – Palaeeudyptinae? New subfamily 2?
- Marambiornis (Late Eocene –? Early Oligocene of Seymour Island, Antarctica) – Palaeeudyptinae, basal, new subfamily 1?
- Mesetaornis (Late Eocene –? Early Oligocene of Seymour Island, Antarctica) – Palaeeudyptinae, basal, new subfamily 1?
- Tonniornis (Late Eocene –? Early Oligocene of Seymour Island, Antarctica)
- Wimanornis (Late Eocene –? Early Oligocene of Seymour Island, Antarctica)
- Duntroonornis (Late Oligocene of Otago, New Zealand) – possibly Spheniscinae
- Korora (Late Oligocene of S Canterbury, New Zealand)
- Platydyptes (Late Oligocene of New Zealand) – possibly not monophyletic; Palaeeudyptinae, Paraptenodytinae or new subfamily?[12]
- Spheniscidae gen. et sp. indet. (Late Oligocene/Early Miocene of Hakataramea, New Zealand)[verification needed]
- Madrynornis (Puerto Madryn Late Miocene of Argentina) – possibly Spheniscinae
- Pseudaptenodytes (Late Miocene/Early Pliocene)
- Dege (Early Pliocene of South Africa) – possibly Spheniscinae
- Marplesornis (Early Pliocene) – possibly Spheniscinae
- Nucleornis (Early Pliocene of Duinfontain, South Africa) – possibly Spheniscinae
- Inguza (Late Pliocene) – probably Spheniscinae; formerly Spheniscus predemersus
- Family Spheniscidae
- Subfamily Palaeeudyptinae – Giant penguins (fossil)
- Crossvallia (Cross Valley Late Paleocene of Seymour Island, Antarctica) – tentatively assigned to this subfamily
- Anthropornis (Middle Eocene? – Early Oligocene of Seymour Island, Antarctica) – tentatively assigned to this subfamily
- Nordenskjoeld's Giant Penguin, Anthropornis nordenskjoeldi
- Icadyptes (Late Eocene of Atacama Desert, Peru)
- Palaeeudyptes (Middle/Late Eocene – Late Oligocene) – polyphyletic; some belong in other subfamilies
- Pachydyptes (Late Eocene)
- Anthropodyptes (Middle Miocene) – tentatively assigned to this subfamily
- Subfamily Paraptenodytinae – Stout-footed penguins (fossil)
- Arthrodytes (San Julian Late Eocene/Early Oligocene – Patagonia Early Miocene of Patagonia, Argentina)
- Paraptenodytes (Early – Late Miocene/Early Pliocene)
- Subfamily Palaeospheniscinae – Slender-footed penguins (fossil)
- Eretiscus (Patagonia Early Miocene of Patagonia, Argentina)
- Palaeospheniscus (Early? – Late Miocene/Early Pliocene) – includes Chubutodyptes
- Subfamily Palaeeudyptinae – Giant penguins (fossil)
Taxonomy Some recent sources[15] apply the phylogenetic taxon Spheniscidae to what here is referred to as Spheniscinae. Furthermore, they restrict the phylogenetic taxon Sphenisciformes to flightless taxa, and establish the phylogenetic taxon Pansphenisciformes as equivalent to the Linnean taxon Sphenisciformes,[16] i.e., including any flying basal "proto-penguins" to be discovered eventually. Given that neither the relationships of the penguin subfamilies to each other nor the placement of the penguins in the avian phylogeny is presently resolved, this is confusing, so the established Linnean system is thus followed here.
Evolution The evolutionary history of penguins is well-researched and represents a showcase of evolutionary biogeography; though as penguin bones of any one species vary much in size and few good specimens are known, the alpha taxonomy of many prehistoric forms still leaves much to be desired. Some seminal articles about penguin prehistory have been published since 2005,[17][18][19][20] the evolution of the living genera can be considered resolved by now.
The basal penguins lived around the time of the Cretaceous–Tertiary extinction event somewhere in the general area of (southern) New Zealand and Byrd Land, Antarctica.[19] Due to plate tectonics, these areas were at that time less than 1,500 kilometers (932 mi) apart rather than the 4,000 kilometers (2,485 mi) of today. The most recent common ancestor of penguins and their sister clade can be roughly dated to the Campanian–Maastrichtian boundary, around 70–68 mya.[18][20][21] What can be said as certainly as possible in the absence of direct (i.e., fossil) evidence is that by the end of the Cretaceous, the penguin lineage must have been evolutionarily well distinct, though much less so morphologically; it is fairly likely that they were not yet entirely flightless at that time, as flightless birds have generally low resilience to the breakdown of trophic webs that follows the initial phase of mass extinctions because of their below-average dispersal capabilities (see also Flightless Cormorant).[citation needed]
The basal fossils The oldest known fossil penguin species is Waimanu manneringi, which lived in the early Paleocene epoch of New Zealand, or about 62 mya.[20] While they were not as well-adapted to aquatic life as modern penguins, Waimanu were generally loon-like birds but already flightless, with short wings adapted for deep diving.[citation needed] They swam on the surface using mainly their feet, but the wings were – as opposed to most other diving birds, living and extinct – already adapting to underwater locomotion.[citation needed]
Perudyptes from northern Peru was dated to 42 mya. An unnamed fossil from Argentina proves that by the Bartonian (Middle Eocene), some 39–38 mya,[22] primitive penguins had spread to South America and were in the process of expanding into Atlantic waters.[16]
Palaeeudyptines During the Late Eocene and the Early Oligocene (40–30 mya), some lineages of gigantic penguins existed. Nordenskjoeld's Giant Penguin was the tallest, growing nearly 1.80 meters (6 ft) tall. The New Zealand Giant Penguin was probably the heaviest, weighing 80 kg or more. Both were found on New Zealand, the former also in the Antarctic farther eastwards.
Traditionally, most extinct species of penguins, giant or small, had been placed in the paraphyletic subfamily called Palaeeudyptinae. More recently, with new taxa being discovered and placed in the phylogeny if possible, it is becoming accepted that there were at least two major extinct lineages. One or two closely related ones occurred in Patagonia, and at least one other—which is or includes the paleeudyptines as recognized today – occurred on most Antarctic and subantarctic coasts.
But size plasticity seems to have been great at this initial stage of penguin radiation: on Seymour Island, Antarctica, for example, around 10 known species of penguins ranging in size from medium to huge apparently coexisted some 35 mya during the Priabonian (Late Eocene).[23] It is not even known whether the gigantic palaeeudyptines constitute a monophyletic lineage, or whether gigantism was evolved independently in a much restricted Palaeeudyptinae and the Anthropornithinae – whether they were considered valid, or whether there was a wide size range present in the Palaeeudyptinae as delimited as usually done these days (i.e., including Anthropornis nordenskjoeldi).[19] The oldest well-described giant penguin, the 5-foot-tall Icadyptes salasi, actually occurred as far north as northern Peru about 36 mya.
In any case, the gigantic penguins had disappeared by the end of the Paleogene, around 25 mya. Their decline and disappearance coincided with the spread of the Squalodontoidea and other primitive, fish-eating toothed whales, which certainly competed with them for food, and were ultimately more successful.[18] A new lineage, the Paraptenodytes, which includes smaller but decidedly stout-legged forms, had already arisen in southernmost South America by that time. The early Neogene saw the emergence of yet another morphotype in the same area, the similarly sized but more gracile Palaeospheniscinae, as well as the radiation that gave rise to the penguin biodiversity of our time.
Origin and systematics of modern penguins Modern penguins consititute two undisputed clades and another two more basal genera with more ambiguous relationships.[17] The origin of the Spheniscinae lies probably in the latest Paleogene, and geographically it must have been much the same as the general area in which the order evolved: the oceans between the Australia-New Zealand region and the Antarctic.[18] Presumedly diverging from other penguins around 40 mya,[18] it seems that the Spheniscinae were for quite some time limited to their ancestral area, as the well-researched deposits of the Antarctic Peninsula and Patagonia have not yielded Paleogene fossils of the subfamily. Also, the earliest spheniscine lineages are those with the most southern distribution.
The genus Aptenodytes appears to be the basalmost divergence among living penguins[24][25] they have bright yellow-orange neck, breast, and bill patches; incubate by placing their eggs on their feet, and when they hatch the chicks are almost naked. This genus has a distribution centered on the Antarctic coasts and barely extends to some subantarctic islands today.
Pygoscelis contains species with a fairly simple black-and-white head pattern; their distribution is intermediate, centered on Antarctic coasts but extending somewhat northwards from there. In external morphology, these apparently still resemble the common ancestor of the Spheniscinae, as Aptenodytes' autapomorphies are in most cases fairly pronounced adaptations related to that genus' extreme habitat conditions. As the former genus, Pygoscelis seems to have diverged during the Bartonian,[26] but the range expansion and radiation that led to the present-day diversity probably did not occur until much later; around the Burdigalian stage of the Early Miocene, roughly 20–15 mya.[18]
The genera Spheniscus and Eudyptula contain species with a mostly subantarctic distribution centered on South America; some, however, range quite far northwards. They all lack carotenoid coloration, and the former genus has a conspicuous banded head pattern; they are unique among living penguins by nesting in burrows. This group probably radiated eastwards with the Antarctic Circumpolar Current out of the ancestral range of modern penguins throughout the Chattian (Late Oligocene), starting approximately 28 mya.[18] While the two genera separated during this time, the present-day diversity is the result of a Pliocene radiation, taking place some 4–2 mya.[18]
The Megadyptes–Eudyptes clade occurs at similar latitudes (though not as far north as the Galapagos Penguin), has its highest diversity in the New Zealand region, and represent a westward dispersal. They are characterized by hairy yellow ornamental head feathers; their bills are at least partly red. These two genera diverged apparently in the Middle Miocene (Langhian, roughly 15–14 mya), but again, the living species of Eudyptes are the product of a later radiation, stretching from about the late Tortonian (Late Miocene, 8 mya) to the end of the Pliocene.[18]
The geographical and temporal pattern or spheniscine evolution corresponds closely to two episodes of global cooling documented in the paleoclimatic record.[18] The emergence of the subantarctic lineage at the end of the Bartonian corresponds with the onset of the slow period of cooling that eventually led to the ice ages some 35 million years later. With habitat on the Antarctic coasts declining, by the Priabonian more hospitable conditions for most penguins existed in the subantarctic regions rather than in Antarctica itself.[27] Notably, the cold Antarctic Circumpolar Current also started as a continuous circumpolar flow only around 30 mya, on the one hand forcing the Antarctic cooling, and on the other facilitating the eastward expansion of Spheniscus to South America and eventually beyond.[18] Despite this, there is no fossil evidence to support the idea a crown radiation from the antarctic continent in the Paleogene.[27]
Later, an interspersed period of slight warming was ended by the Middle Miocene Climate Transition, a sharp drop in global average temperature from 14–12 mya, and similar abrupt cooling events followed at 8 mya and 4 mya; by the end of the Tortonian, the Antarctic ice sheet was already much like today in volume and extent. The emergence of most of today's subantarctic penguin species almost certainly was caused by this sequence of Neogene climate shifts.
Relationship to other bird orders Penguin ancestry beyond Waimanu remains unknown and not well-resolved by molecular or morphological analyses. The latter tend to be confounded by the strong adaptive autapomorphies of the Sphenisciformes; a sometimes perceived fairly close relationship between penguins and grebes is almost certainly an error based on both groups' strong diving adaptations, which are homoplasies. On the other hand, different DNA sequence datasets do not agree in detail with each other either.
Humboldt Penguins in an aquarium. The penguin is an accomplished swimmer, having flippers instead of wings. What seems clear is that penguins belong to a clade of Neoaves (living birds except paleognaths and fowl) that comprises what is sometimes called "higher waterbirds" to distinguish them from the more ancient waterfowl. This group contains such birds as storks, rails, and the seabirds, with the possible exception of the Charadriiformes.[28]
Inside this group, penguin relationships are far less clear. Depending on the analysis and dataset, a close relationship to Ciconiiformes[20] or to Procellariiformes[18] has been suggested. Some think the penguin-like plotopterids (usually considered relatives of anhingas and cormorants) may actually be a sister group of the penguins, and that penguins may have ultimately shared a common ancestor with the Pelecaniformes and consequently would have to be included in that order, or that the plotopterids were not as close to other pelecaniforms as generally assumed, which would necessitate splitting the traditional Pelecaniformes in three.[29]
Anatomy and physiology Orcas swim by an iceberg with Adelie Penguins in the Ross Sea, Antarctica. The Drygalski ice tongue is visible in the background. Penguins are superbly adapted to aquatic life. Their vestigial wings have become flippers, useless for flight in the air. In the water, however, penguins are astonishingly agile. Penguins' swimming looks very similar to bird's flight in the air.[30] Within the smooth plumage a layer of air is preserved, ensuring buoyancy. The air layer also helps insulate the birds in cold waters. On land, penguins use their tails and wings to maintain balance for their upright stance.
All penguins are countershaded for camouflage – that is, they have black backs and wings with white fronts.[31] A predator looking up from below (such as an orca or a leopard seal) has difficulty distinguishing between a white penguin belly and the reflective water surface. The dark plumage on their backs camouflages them from above.
Diving penguins reach 6 to 12 km/h (3.7 to 7.5 mph), though there are reports of velocities of 27 km/h (17 mph) (which are more realistic in the case of startled flight)[citation needed]. The small penguins do not usually dive deep; they catch their prey near the surface in dives that normally last only one or two minutes. Larger penguins can dive deep in case of need. Dives of the large Emperor Penguin have been recorded reaching a depth of 565 m (1,870 ft) for up to 22 minutes.
Penguins either waddle on their feet or slide on their bellies across the snow, a movement called "tobogganing", which conserves energy while moving quickly. They also jump with both feet together if they want to move more quickly or cross steep or rocky terrain.
Penguins have an average sense of hearing for birds;[32] this is used by parents and chicks to locate one another in crowded colonies.[33] Their eyes are adapted for underwater vision, and are their primary means of locating prey and avoiding predators; in air it has been suggested that they are nearsighted, although research has not supported this hypothesis.[34]
Gentoo Penguin swimming underwater at Nagasaki Penguin Aquarium. Penguins have a thick layer of insulating feathers that keeps them warm in water (heat loss in water is much greater than in air). The Emperor Penguin (the largest penguin) has the largest body mass of all penguins, which further reduces relative surface area and heat loss. They also are able to control blood flow to their extremities, reducing the amount of blood that gets cold, but still keeping the extremities from freezing. In the extreme cold of the Antarctic winter, the females are at sea fishing for food leaving the males to brave the weather by themselves. They often huddle together to keep warm and rotate positions to make sure that each penguin gets a turn in the center of the heat pack.
They can drink salt water because their supraorbital gland filters excess salt from the bloodstream.[35][36][37] The salt is excreted in a concentrated fluid from the nasal passages.
The Auk of the Northern Hemisphere is superficially similar to penguins. They are not related to the penguins at all, but considered by some[who?] to be a product of moderate convergent evolution.[38]
Isabelline penguins Isabelline Adélie Penguin on Gourdin Island. Perhaps one in 50,000 penguins (of most species) are born with brown rather than black plumage. These are called isabelline penguins, possibly in reference to the legend that the archduchess Isabella of Austria vowed not to change her undergarments until her husband united the northern and southern Low Countries by taking the city of Ostend—which took three years to accomplish.[39] Isabellinism is different from albinism. Isabelline penguins tend to live shorter lives than normal penguins, as they are not well-camouflaged against the deep, and are often passed over as mates.
Distribution and habitat Although all penguin species are native to the southern hemisphere, they are not found only in cold climates, such as Antarctica. In fact, only a few species of penguin actually live so far south. At least 10[verification needed] species live in the temperate zone; one, the Galápagos Penguin, lives as far north as the Galápagos Islands, but this is only made possible by the cold, rich waters of the Antarctic Humboldt Current that flows around these islands.[40]
Several authors have suggested that penguins are a good example of Bergmann's Rule [41][42] where larger bodied populations live at higher latitudes than smaller bodied populations. There is some disagreement about this, and several other authors have noted that there are fossil penguin species that contradict this hypothesis and that ocean currents and upwellings are likely to have had a greater effect on species diversity than latitude alone.[43][44]
Major populations of penguins are found in: Antarctica, Australia, New Zealand, South America, and South Africa.[45][46]
Behaviour Chinstrap Penguins in Antarctica. Breeding Penguins for the most part breed in large colonies, the exceptions being the Yellow-eyed and Fiordland species; these colonies may range in size from as few as a 100 pairs for Gentoo Penguins, to several hundred thousand in the case of King, Macaroni and Chinstrap Penguins.[47] Living in colonies results in a high level of social interaction between birds, which has led to a large repertoire of visual as well as vocal displays in all penguin species.[48] Agonistic displays are those intended to confront or drive off, or alternately appease and avoid conflict with, other individuals.[48]
Penguins form monogamous pairs for a breeding season, though the rate the same pair recouples varies drastically. Most penguins lay two eggs in a clutch, although the two largest species, the Emperor and the King Penguins, lay only one.[49] With the exception of the Emperor Penguin, all penguins share the incubation duties.[50] These incubation shifts can last days and even weeks as one member of the pair feeds at sea.
Penguins generally only lay one brood; the exception is the Little Penguin, which can raise two or three broods in a season.[51]
Penguin eggs are smaller than any other bird species when compared proportionally to the weight of the parent birds; at 52 g (2 oz), the Little Penguin egg is 4.7% of its mothers' weight, and the 450 g (1 lb) Emperor Penguin egg is 2.3%.[49] The relatively thick shell forms between 10 and 16 % of the weight of a penguin egg, presumably to minimise risk of breakage in an adverse nesting environment. The yolk, too, is large, and comprises 22–31 % of the egg. Some yolk often remains when a chick is born, and is thought to help sustain it if parents are delayed in returning with food.[52]
When mothers lose a chick, they sometimes attempt to "steal" another mother's chick, usually unsuccessfully as other females in the vicinity assist the defending mother in keeping her chick.[citation needed] In some species, such as Emperor Penguins, young penguins assemble in large groups called crèches.
Penguins and humans Cook on the Endurance preparing a penguin for consumption Penguins seem to have no special fear of humans, and have approached groups of explorers without hesitation. This is probably because penguins have no land predators in Antarctica or the nearby offshore islands. Instead, penguins are at risk at sea from predators such as the leopard seal. Typically, penguins do not approach closer than about 3 meters (10 ft) at which point they become nervous. This is also the distance that Antarctic tourists are told to keep from penguins (tourists are not supposed to approach closer than 3 meters, but are not expected to withdraw if the penguins come closer).
In popular culture A penguin encounters a human during Antarctic summer. Tux the Linux kernel mascot. Main article: Penguins in popular culture Penguins are popular around the world, primarily for their unusually upright, waddling gait and (compared to other birds) lack of fear of humans. Their striking black-and-white plumage is often likened to a tuxedo suit. Mistakenly, some artists and writers have penguins based at the North Pole. This is incorrect, as there are almost no wild penguins in the northern hemisphere, except the small group on the northernmost of the Galápagos. The cartoon series Chilly Willy helped perpetuate this myth, as the title penguin would interact with northern-hemisphere species such as polar bears and walruses.
Penguins have been the subject of many books and films such as Happy Feet and Surf's Up, both CGI films; March of the Penguins, a documentary based on the migration process of the Emperor Penguin; and a parody titled Farce of the Penguins. Mr. Popper's Penguins is a children's book written by Richard & Florence Atwater; it was named a Newbery Honor Book in 1939. Penguins have also found their way into a number of cartoons and television dramas; perhaps the most notable of these is Pingu, created by Silvio Mazzola in 1986 and covering more than 100 short episodes. Entertainment Weekly put it on its end-of-the-decade, "best-of" list, saying, "Whether they were walking (March of the Penguins), dancing (Happy Feet), or hanging ten (Surf's Up), these oddly adorable birds took flight at the box office all decade long."[53]
The tendency of penguins to form large groups feeds the stereotype that they all look exactly alike, a popular notion exploited by cartoonists such as Gary Larson.
Penguins featured regularly in the cartoons of UK cartoonist Steve Bell in his strip in The Guardian Newspaper, particularly during and following the Falklands War.
In the mid-2000s, penguins became one of the most publicized species of animals that form lasting homosexual couples. A children's book, And Tango Makes Three, was written about one such penguin family in the New York Zoo.
Petite creatures, they are found inhabiting mainly the country of Antarctica and might also be seen in the cold costal areas of South America, New Zealand, Australia and South Africa. They are basically aquatic birds, which can swim but cannot fly. Penguins have white undersides and a dark upper side (usually black or dark brown). They are great swimmers and on land, they either waddle on their feet or slide on their bellies. Want to know more about penguins? Read on further and get some very interesting facts and information on the adorable creatures. Facts about Penguin
- Class: Aves
- Order: Sphenisciformes
- Family: Spheniscidae
- Genus: Aptenodytes, Eudyptes, Eudyptula, Megadyptes, Pygoscelis and Spheniscus
- Number of Species: 17 to 20 living species
- Height : 1.1 m (3 ft 7 in)
- Weight: 35 kg (75 lb)
- Color: Black/Brown and White
- Age: 15-20 years
- Smallest Breed: Little Blue Penguin (40 cm tall, with weight of 1 kg)
- Largest Breed: Emperor Penguins (115 cm tall)
- Natural Habitat: Mainly in Antarctica and also in cold costal areas of South America, New Zealand, Australia and South Africa
- Diet: Krill, fish, squid and other forms of sea life
- Swimming Speed: Up to 25 miles per hour
- Reproductive Age: 3-5 years
- Number of Eggs: 1-2
- Penguins are birds, but they cannot fly. However, they are expert at swimming.
- Penguins live in large groups called colonies or rookery.
- Penguins breed only on land and lay eggs.
- In case of penguins, it is the male who takes care of the egg after the female lays it.
- Penguins have no biological defenses against germs that thrive in conditions other than cold ones. This is the reason why so many of them die in zoos.
- In order to move quickly on ice, penguins fall on their bellies and, using their feet, push themselves across the ice.
- Being strong swimmers, penguins can jump up to six feet out of water, while landing on the surface.
- Penguins cannot swim backwards.
- A penguin can hold its breath for six minutes underwater.
- Penguins have insulating layers on their body, consisting of tightly packed feathers, air, skin and blubber, which help them keep warm.
- A penguin fluffs out its feathers, away from the body, to cool itself.
- The total population of penguins in the world is estimated to be somewhere around 100 million.
- Penguins can drink salt water.
12/6/10 Reindeer
Reindeer, also known as caribou, belongs to the family of deer (Cervidae) and is basically found inhabiting bleak arctic plain, or tundra, and the surrounding forest and mountain areas. The wild reindeer can be found in Norway, Siberia, Greenland, Alaska and Canada in large population and about 50 of them are seen around the Cairngorms region in Scotland. The domesticated reindeer inhabits Northern Fennoscandia, Russia and Ireland. It survives on a diet of mainly lichens, mosses, leaves of willows and birches, sedges, grasses and stunted shrubs and has an average lifespan of twelve to fifteen years. In the following lines, we have provided some more interesting facts and amazaing information on reindeer. The reindeer is a majestic animal that inhabits the frozen arctic tundra. It has adapted remarkably to a harsh, barren habitat where food is scarce much of the year. It is an excellent swimmer. Aided by a thick coat that traps air and gives good buoyancy in the water, it can easily swim across wide rivers.
The reindeer inhabits the bleak arctic plain or tundra, and the surrounding forest and mountain areas. Within this harsh and freezing-cold environment, reindeer live together in herds.The smallest herd may contain 20 animals, while the largest may contain thousands. The herd is almost constantly on the move.
BREEDING
The reindeer mates sometime between August and November, depending on location, but mostly in October. This is known as the rutting season, and the male becomes very aggressive, fighting with other males as he competes to win control of a harem of 5 to 15 females.
As the time approaches to give birth, the female leaves the herd and chooses a secluded spot. She usually returns to the same spot each year to calve, or bear young. The calf is born between late May and early June, when the herd is at the summer grazing grounds. It weighs 11 - 20 pounds and can stand within minutes after being born. It suckles until it is five to six months old.Unlike many baby deer, the reindeer fawn's coat is not marked with camouflaging spots. Becasue they are born in early summer, the calves have enough time to feed and grow strong before the Fall migration, when predators are most likely to attack.The calf's antlers begin to grow when the animal is a year old.
FOOD & FEEDING
The reindeer is a plant eater and eats a wide variety of vegetation. The mainstay of its diet are the lichens and tough grass that grows on the tundra. In the spring, the reindeer will graze the newly sprouted shoots of grass and shrubs. The green leaves of birches and willows are eaten at the summer grazing grounds.During the harsh winter months, the reindeer has a difficult time finding enough to eat. It will dig holes in the snow several feet deep to get to the lichens and moss underneath. At the same time, it feeds on the twigs of any shrubs it finds under or above the snow.
KEY FACTS
Size Length: 48-86 in. Weight: 200-600 lbs. Breeding Sexual maturity: 29-41 months Mating: August to November Gestation: About 8 months Number of young: Usually 1 Lifestyle
Habit: Sociable.Herds may number several thousand. Diet: Lichens, mosses,grasses Lifespan: 12-15 years Number of young: Usually 1
DID YOU KNOW?
Facts About Reindeer Bionomial Name: Rangifer tarandus Class: Mammalia Order: Artiodactyla Family: Cervidae Subfamily: Capreolinae Genus: Rangifer Species: R. tarandus Height (shoulder): 3-4 ft Length: 48-86 inches Weight: 200-600 lbs Color: Brown Age: 12-15 years Natural Habitat: Frozen arctic tundra region Diet: Lichens, mosses, grasses Reproductive Age: 29-41 months Number of Offspring: Usually One Gestation Period: About 8 months Interesting & Amazing Information On Reindeer
The reindeer inhabits the bleak arctic plain or tundra, and the surrounding forest and mountain areas. Within this harsh and freezing-cold environment, reindeer live together in herds.The smallest herd may contain 20 animals, while the largest may contain thousands. The herd is almost constantly on the move.
BREEDING
The reindeer mates sometime between August and November, depending on location, but mostly in October. This is known as the rutting season, and the male becomes very aggressive, fighting with other males as he competes to win control of a harem of 5 to 15 females.
As the time approaches to give birth, the female leaves the herd and chooses a secluded spot. She usually returns to the same spot each year to calve, or bear young. The calf is born between late May and early June, when the herd is at the summer grazing grounds. It weighs 11 - 20 pounds and can stand within minutes after being born. It suckles until it is five to six months old.Unlike many baby deer, the reindeer fawn's coat is not marked with camouflaging spots. Becasue they are born in early summer, the calves have enough time to feed and grow strong before the Fall migration, when predators are most likely to attack.The calf's antlers begin to grow when the animal is a year old.
FOOD & FEEDING
The reindeer is a plant eater and eats a wide variety of vegetation. The mainstay of its diet are the lichens and tough grass that grows on the tundra. In the spring, the reindeer will graze the newly sprouted shoots of grass and shrubs. The green leaves of birches and willows are eaten at the summer grazing grounds.During the harsh winter months, the reindeer has a difficult time finding enough to eat. It will dig holes in the snow several feet deep to get to the lichens and moss underneath. At the same time, it feeds on the twigs of any shrubs it finds under or above the snow.
KEY FACTS
Size Length: 48-86 in. Weight: 200-600 lbs. Breeding Sexual maturity: 29-41 months Mating: August to November Gestation: About 8 months Number of young: Usually 1 Lifestyle
Habit: Sociable.Herds may number several thousand. Diet: Lichens, mosses,grasses Lifespan: 12-15 years Number of young: Usually 1
DID YOU KNOW?
- The reindeer is the only species of deer in which the female has horns-perhaps to help her compete for scarce food supplies.
- A day-old reindeer calf can outrun a man.
- Male reindeer have inflatable pouches of skin under their throats. This amplifies the roar during the rutting season.
Facts About Reindeer Bionomial Name: Rangifer tarandus Class: Mammalia Order: Artiodactyla Family: Cervidae Subfamily: Capreolinae Genus: Rangifer Species: R. tarandus Height (shoulder): 3-4 ft Length: 48-86 inches Weight: 200-600 lbs Color: Brown Age: 12-15 years Natural Habitat: Frozen arctic tundra region Diet: Lichens, mosses, grasses Reproductive Age: 29-41 months Number of Offspring: Usually One Gestation Period: About 8 months Interesting & Amazing Information On Reindeer
- Reindeer are excellent swimmers and can easily swim across wide rivers.
- They live together in large groups, known as herds, the smallest of which contains usually 20 members. On the other extreme, large herbs of reindeer might comprise of thousand members also.
- Male reindeer are solitary, while female reindeer tend to stay in herds.
- In summers, reindeer migrate long distances to the north, for fresh grazing and come back to the more temperate climates of the south, in winter, for shelter.
- A reindeer’s coat is usually brown, with a pale breast and belly in summers, while the coat turns lighter and whitish during the winters.
- A single reindeer male, known as bull, wins control over a harem of 5 to 15 females, known as cows, in the mating season.
- The calf of a reindeer weighs 11 - 20 pounds and can stand on its legs within minutes of being born.
- A day-old reindeer calf is capable of outrunning a man.
- Reindeer is the only deer that can be domesticated. It provides butter, meat, cheese, clothing and transportation to humans.
- Male reindeer shed their antlers at the end of winter season, after the rut, and grow them again around January-February.
- Female reindeer and calves shed their antlers around March-April and start growing new ones immediately after shedding the old ones.
- The inflatable pouches of skin found under the reindeer’s throat amplify the roaring during rutting season.
- Reindeer can lower the temperature in their legs to just above freezing, in extremely cold weather. This way, they avoid loss of body heat.
- In winters, the facial hair of reindeer grows down to the lips, to protect the muzzle when reindeer graze in snow.
- Reindeer represent the only deer species, apart from caribou, in which males, females and even calves produce antlers.
- Reindeer milk is very high in protein and fats.
- In winters, reindeer prefer snow, over water.
11/1/10 Turkey
For more info on the Turkey, follow this link: http://animalimania.weebly.com/turkey-facts.html
A turkey is either of two or three living species of large birds in the genus Meleagris. One species, Meleagris gallopavo, commonly known as the Wild Turkey, is native to the forests of North America. The other species, Meleagris ocellata, known as the Ocellated Turkey, is native to the forests of the Yucatán Peninsula.
The domestic turkey is a descendant of the Wild Turkey and features prominently in the menu of the U.S. and Canadian holidays of Thanksgiving and that of Christmas in many countries.
Turkeys are classed in the taxonomicorder of Galliformes. Within this order they are relatives of the family/subfamilyTetraonidae (grouse). Turkeys have a distinctive fleshy wattle that hangs from the underside of the beak, and a fleshy protuberance that hangs from the top of its beak called a snood. With wingspans of 1.5–1.8 metres (4.9–5.9 ft), the turkeys are by far the largest birds in the open forests in which they live. As with many galliform species, the female (hen) is smaller and is much less colorful than the male (tom or gobbler)History and naming
When Europeans first encountered turkeys in the America Continent they incorrectly identified the birds as a type of guineafowl (Numididae), also known as Turkey fowl (or Turkey hen and Turkey cock) from their importation to Central Europe through Turkey, and that name, shortened to just the name of the country, stuck as the name of the bird.[1][2][3] The confusion between these kinds of birds from related but different families is also reflected in the scientific name for the turkey genus: meleagris (μελεαγρίς) is Greek for guineafowl. The domesticated turkey is attributed to Aztec agriculture, which addressed one subspecies of Meleagris gallopavo local to the present day states of Jalisco and Guerrero.[4]
The names for M. gallopavo in other languages also frequently reflect its exotic origins, seen from an Old World viewpoint, and add to the confusion about where turkeys actually came from. The many references to India seen in common names go back to a combination of two factors: first, the genuine belief that the newly-discovered Americas were in fact a part of Asia, and second, the tendency during that time to attribute exotic animals and foods to a place that symbolized far-off, exotic lands. The latter is reflected in terms like "Muscovy Duck" (which is from South America, not Muscovy). This was a major reason why the name Turkey fowl stuck to Meleagris rather than to the guinea fowl (Numida meleagris): the Ottoman Empire represented the exotic East.[original research?]
The name given to a group of turkeys is a rafter, although they are sometimes incorrectly referred to as a gobble or flock.[5]
Several other birds which are sometimes called turkeys are not particularly closely related: the Australian Brush-turkey is a megapode, and the bird sometimes known as the "Australian Turkey" is in fact the Australian Bustard, a gruiform. The bird sometimes called a Water Turkey is actually an Anhinga (Anhinga rufa). The 16th century English navigator William Strickland is generally credited with introducing the turkey into England.[6][7] His family coat of arms showing a turkey cock as the family crest, is among the earliest known pictures of a turkey.[6]
Flight
While large domesticated turkeys are generally unable to fly, smaller, lighter domesticated turkeys known as heritage turkeys and wild turkeys can fly. In domesticated turkeys the ability to fly depends directly on weight, while even heavy adult wild turkeys can fly well enough to avoid predators by taking off and flying up to 100 yards (91 m) and perching in tree branches. Turkey poults (chicks) cannot fly for the first two weeks after hatchingFossil record
Many turkeys have been described from fossils. The Meleagrididae are known from the Early Miocene (c. 23 mya) onwards, with the extinctgeneraRhegminornis (Early Miocene of Bell, U.S.) and Proagriocharis (Kimball Late Miocene/Early Pliocene of Lime Creek, U.S.). The former is probably a basal turkey, the other a more contemporary bird not very similar to known turkeys; both were much smaller birds. A turkey fossil not assignable to genus but similar to Meleagris is known from the Late Miocene of Westmoreland County, Virginia.[8] In the modern genus Meleagris, a considerable number of species have been described, as turkey fossils are robust, fairly often found, and turkeys show much variation among individuals. Many of these supposed fossilized species are now considered junior synonyms. One, the well-documented California Turkey Meleagris californica,[9] became extinct recently enough to have been hunted by early human settlers[10] and it is believed its demise was due to the combined pressures of climate change at the end of the last glacial period and hunting.[11] The modern species and the California Turkey seem to have diverged approximately one million years ago.
Turkeys known from fossils
Meleagris sp. (Early Pliocene of Bone Valley, U.S.)
Meleagris sp. (Late Pliocene of Macasphalt Shell Pit, U.S.)
Meleagris californica (Late Pleistocene of SW U.S.) - formerly Parapavo/Pavo
Meleagris crassipes (Late Pleistocene of SW North America)
Turkeys have been considered by many authorities to be of their own family, the Meleagrididae but a recent genomic analyses of a retrotransposon marker groups turkeys in the family Phasianidae.[12]
Other facts
Lake Tuz, the third-largest lake in Turkey, coincidentally looks like a turkey (or similar bird), happens to be a macroscopically-visible geographical feature at the country level, and is roughly near the center of the country.
A turkey is either of two or three living species of large birds in the genus Meleagris. One species, Meleagris gallopavo, commonly known as the Wild Turkey, is native to the forests of North America. The other species, Meleagris ocellata, known as the Ocellated Turkey, is native to the forests of the Yucatán Peninsula.
The domestic turkey is a descendant of the Wild Turkey and features prominently in the menu of the U.S. and Canadian holidays of Thanksgiving and that of Christmas in many countries.
Turkeys are classed in the taxonomicorder of Galliformes. Within this order they are relatives of the family/subfamilyTetraonidae (grouse). Turkeys have a distinctive fleshy wattle that hangs from the underside of the beak, and a fleshy protuberance that hangs from the top of its beak called a snood. With wingspans of 1.5–1.8 metres (4.9–5.9 ft), the turkeys are by far the largest birds in the open forests in which they live. As with many galliform species, the female (hen) is smaller and is much less colorful than the male (tom or gobbler)History and naming
When Europeans first encountered turkeys in the America Continent they incorrectly identified the birds as a type of guineafowl (Numididae), also known as Turkey fowl (or Turkey hen and Turkey cock) from their importation to Central Europe through Turkey, and that name, shortened to just the name of the country, stuck as the name of the bird.[1][2][3] The confusion between these kinds of birds from related but different families is also reflected in the scientific name for the turkey genus: meleagris (μελεαγρίς) is Greek for guineafowl. The domesticated turkey is attributed to Aztec agriculture, which addressed one subspecies of Meleagris gallopavo local to the present day states of Jalisco and Guerrero.[4]
The names for M. gallopavo in other languages also frequently reflect its exotic origins, seen from an Old World viewpoint, and add to the confusion about where turkeys actually came from. The many references to India seen in common names go back to a combination of two factors: first, the genuine belief that the newly-discovered Americas were in fact a part of Asia, and second, the tendency during that time to attribute exotic animals and foods to a place that symbolized far-off, exotic lands. The latter is reflected in terms like "Muscovy Duck" (which is from South America, not Muscovy). This was a major reason why the name Turkey fowl stuck to Meleagris rather than to the guinea fowl (Numida meleagris): the Ottoman Empire represented the exotic East.[original research?]
The name given to a group of turkeys is a rafter, although they are sometimes incorrectly referred to as a gobble or flock.[5]
Several other birds which are sometimes called turkeys are not particularly closely related: the Australian Brush-turkey is a megapode, and the bird sometimes known as the "Australian Turkey" is in fact the Australian Bustard, a gruiform. The bird sometimes called a Water Turkey is actually an Anhinga (Anhinga rufa). The 16th century English navigator William Strickland is generally credited with introducing the turkey into England.[6][7] His family coat of arms showing a turkey cock as the family crest, is among the earliest known pictures of a turkey.[6]
Flight
While large domesticated turkeys are generally unable to fly, smaller, lighter domesticated turkeys known as heritage turkeys and wild turkeys can fly. In domesticated turkeys the ability to fly depends directly on weight, while even heavy adult wild turkeys can fly well enough to avoid predators by taking off and flying up to 100 yards (91 m) and perching in tree branches. Turkey poults (chicks) cannot fly for the first two weeks after hatchingFossil record
Many turkeys have been described from fossils. The Meleagrididae are known from the Early Miocene (c. 23 mya) onwards, with the extinctgeneraRhegminornis (Early Miocene of Bell, U.S.) and Proagriocharis (Kimball Late Miocene/Early Pliocene of Lime Creek, U.S.). The former is probably a basal turkey, the other a more contemporary bird not very similar to known turkeys; both were much smaller birds. A turkey fossil not assignable to genus but similar to Meleagris is known from the Late Miocene of Westmoreland County, Virginia.[8] In the modern genus Meleagris, a considerable number of species have been described, as turkey fossils are robust, fairly often found, and turkeys show much variation among individuals. Many of these supposed fossilized species are now considered junior synonyms. One, the well-documented California Turkey Meleagris californica,[9] became extinct recently enough to have been hunted by early human settlers[10] and it is believed its demise was due to the combined pressures of climate change at the end of the last glacial period and hunting.[11] The modern species and the California Turkey seem to have diverged approximately one million years ago.
Turkeys known from fossils
Meleagris sp. (Early Pliocene of Bone Valley, U.S.)
Meleagris sp. (Late Pliocene of Macasphalt Shell Pit, U.S.)
Meleagris californica (Late Pleistocene of SW U.S.) - formerly Parapavo/Pavo
Meleagris crassipes (Late Pleistocene of SW North America)
Turkeys have been considered by many authorities to be of their own family, the Meleagrididae but a recent genomic analyses of a retrotransposon marker groups turkeys in the family Phasianidae.[12]
Other facts
Lake Tuz, the third-largest lake in Turkey, coincidentally looks like a turkey (or similar bird), happens to be a macroscopically-visible geographical feature at the country level, and is roughly near the center of the country.
10/4/10 Bats
Classification and evolution Giant Golden-crowned Flying-fox, Acerodon jubatus. Bats are mammals. Sometimes they are mistakenly called "flying rodents" or "flying rats", and they can also be mistaken for insects and birds. There are two suborders of bats:
The phylogenetic relationships of the different groups of bats have been the subject of much debate. The traditional subdivision between Megachiroptera and Microchiroptera reflects the view that these groups of bats have evolved independently of each other for a long time, from a common ancestor that was already capable of flight. This hypothesis recognized differences between microbats and megabats and acknowledged that flight has only evolved once in mammals. Most molecular biological evidence supports the view that bats form a single or monophyletic group.[5]
Researchers have proposed alternate views of chiropteran phylogeny and classification, but more research is needed.
Genetic evidence indicates that megabats originated during the early Eocene and should be placed within the four major lines of microbats.
Consequently, two new suborders based on molecular data have been proposed. The new suborder Yinpterochiroptera includes the Pteropodidae or megabat family as well as the Rhinolophidae, Megadermatidae, and Rhinopomatidae families. The new suborder Yangochiroptera includes all the remaining families of bats (all of which use laryngeal echolocation). These two new suborders are strongly supported by statistical tests. Teeling (2005) found 100% bootstrap support in all maximum likelihood analyses for the division of Chiroptera into these two modified suborders. This conclusion is further supported by a fifteen-base pair deletion in BRCA1 and a seven-base pair deletion in PLCB4 present in all Yangochiroptera and absent in all Yinpterochiroptera.[6] The Chiropteran phylogeny based on molecular evidence is controversial because microbat paraphyly implies that one of two seemingly unlikely hypotheses occurred. The first suggests that laryngeal echolocation evolved twice in Chiroptera, once in Yangochiroptera and once in the rhinolophoids.[7][8] The second proposes that laryngeal echolocation had a single origin in Chiroptera, was subsequently lost in the family Pteropodidae (all megabats), and later evolved as a system of tongue-clicking in the genus Rousettus.[9]
Common Pipistrelle, Pipistrellus pipistrellus. Analyses of the sequence of the "vocalization" gene, FoxP2 was inconclusive of whether laryngeal echolocation was secondarily lost in the pteropodids or independently gained in the echolocating lineages[10]. However, analyses of the "hearing" gene, Prestin seemed to favor the independent gain in echolocating species rather than a secondary loss in the pteropodids.[11]
In addition to Yinpterochiroptera and Yangochiroptera, the names Pteropodiformes and Vespertilioniformes have also been proposed for these suborders.[12][13] Under this new proposed nomenclature, the suborder Pteropodiformes includes all extant bat families more closely related to the genus Pteropus than the genus Vespertilio, while the suborder Vespertilioniformes includes all extant bat families more closely related to the genus Vespertilio than to the genus Pteropus.
In the 1980s, a hypothesis based on morphological evidence was offered that stated that the Megachiroptera evolved flight separately from the Microchiroptera. The so-called flying primates theory proposed that when adaptations to flight are removed, the Megachiroptera are allied to primates by anatomical features that are not shared with Microchiroptera. One example is that the brains of megabats show a number of advanced characteristics that link them to primates. Although recent genetic studies support the monophyly of bats,[14] debate continues as to the meaning of available genetic and morphological evidence.[15]
Little fossil evidence is available to help map the evolution of bats, since their small, delicate skeletons do not fossilize very well. However a Late Cretaceous tooth from South America resembles that of an early Microchiropteran bat. The oldest known definitely identified bat fossils, such as Icaronycteris, Archaeonycteris, Palaeochiropteryx and Hassianycteris, are from the early Eocene period, 52.5 million years ago[5]. These fossil bats were already very similar to modern microbats. Archaeopteropus, formerly classified as the earliest known megachiropteran, is now classified as a microchiropteran.
Bats were formerly grouped in the superorder Archonta along with the treeshrews (Scandentia), colugos (Dermoptera), and the primates, because of the apparent similarities between Megachiroptera and such mammals. Genetic studies have now placed bats in the superorder Laurasiatheria along with carnivorans, pangolins, odd-toed ungulates, even-toed ungulates, and cetaceans.[1]
"Chiroptera" from Ernst Haeckel's Kunstformen der Natur, 1904 The traditional classification of bats is:
Fossil bats There are few fossilized remains of bats, as they are terrestrial and light-boned. An Eocene bat, Onychonycteris finneyi, was found in the fifty-two-million-year-old Green River Formation in South Dakota, United States, in 2004 and was added as a new genus and placed in a new family when published in Nature in 2008.[16] It had characteristics indicating that it could fly, yet the well-preserved skeleton showed that the cochlea of the inner ear lacked development needed to support the greater hearing abilities of modern bats. This provided evidence that flight in bats developed well before echolocation. The team that found the remains of this species, named Onychonycteris finneyi, recognized that it lacked ear and throat features present not only in echolocating bats today, but also in other known prehistoric species. Fossil remains of another Eocene bat, Icaronycteris, were found in 1960.
The appearance and flight movement of bats 52.5 million years ago were different from those of bats today. Onychonycteris had claws on all five of its fingers, whereas modern bats have at most two claws appearing on two digits of each hand. It also had longer hind legs and shorter forearms, similar to climbing mammals that hang under branches such as sloths and gibbons. This palm-sized bat had broad, short wings suggesting that it could not fly as fast or as far as later bat species. Instead of flapping its wings continuously while flying, Onychonycteris likely alternated between flaps and glides while in the air. Such physical characteristics suggest that this bat did not fly as much as modern bats do, rather flying from tree to tree and spending most of its waking day climbing or hanging on the branches of trees.[17]
Anatomy Skeleton of a Greater Mouse-eared Bat (Myotis myotis). Echolocation Spectrogram of Pipistrellus Bat vocalizations. Detail is shown as the pulse duty cycle increases during a close approach to prey. The bat appears to use a hybrid pulse which combines a sharp falling frequency chirp with an extended constant frequency tail. Such a waveform may offer combined benefits of range estimation as well as Doppler shift detection. Spectrogram generated with Fatpigdog's PC based Real Time FFT Spectrum Analyzer. Pipistrellus Pulses Recording of Pipistrellus bat approaching its prey. Problems listening to this file? See media help. Bat echolocation is a perceptual system where ultrasonic sounds are emitted specifically to produce echoes. By comparing the outgoing pulse with the returning echoes the brain and auditory nervous system can produce detailed images of the bat's surroundings. This allows bats to detect, localize and even classify their prey in complete darkness. At 130 decibels in intensity, bat calls are some of the most intense airborne animal sounds.[18]
To clearly distinguish returning information, bats must be able to separate their calls from the echoes they receive. Microbats use two distinct approaches.
1.Low Duty Cycle Echolocation: Bats can separate their calls and returning echos by time. Bats that use this approach time their short calls to finish before echoes return. This is important because these bats contract their middle ear muscles when emitting a call so that they can avoid deafening themselves. The time interval between call and echo allows them to relax these muscles so they can clearly hear the returning echo.[19] The delay of the returning echos provide the bat with the ability to estimate range to their prey.
2. High Duty Cycle Echolocation: Bats emit a continuous call and separate pulse and echo in frequency. The ears of these bats are sharply tuned to a specific frequency range. They emit calls outside of this range to avoid self-deafening. They then receive echoes back at the finely tuned frequency range by taking advantage of the Doppler shift of their motion in flight. The Doppler shift of the returning echos yield information relating to the motion and location of the bat's prey. These bats must deal with changes in the Doppler shift due to changes in their flight speed. They have adapted to change their pulse emission frequency in relation to their flight speed so echoes still return in the optimal hearing range.[20]
The new Yinpterochiroptera and Yangochiroptera classification of bats that are supported by molecular evidence, suggest two possibilities for the evolution of echolocation. It may have been gained once in a common ancestor of all bats and was then subsequently lost in the Old World fruit bats, only to be regained in the Horse-Shoe bats; or echolocation was evolved independent in both the Yinpterochiroptera and Yangochirpotera lineages.[21]
Two groups of moths exploit a bat sense to echolocate: tiger moths produce ultrasonic signals to warn the bats that they (the moths) are chemically protected or aposematic. This was once thought to be the biological equivalent of "radar jamming", but this theory has yet to be confirmed. The moths Noctuidae have a hearing organ called a tympanum, which responds to an incoming bat signal by causing the moth's flight muscles to twitch erratically, sending the moth into random evasive manoeuvres.
Eyes Although the eyes of most microbat species are small and poorly developed, leading to poor visual acuity, none of them are blind. Vision is used to navigate microbats especially for long distances when beyond the range of echolocation. It has even been discovered that some species are able to detect ultraviolet light. They also have a high quality sense of smell and hearing. Bats hunt at night to avoid competition with birds, and travel large distances at most 800 km, in their search for food.[2]
Wings Thermographic image of a bat using trapped air as insulation. The finger bones of bats are much more flexible than those of other mammals. One reason is that the cartilage in their fingers lacks calcium and other minerals nearer the tips, increasing their ability to bend without splintering. The cross-section of the finger bone is also flattened compared to the circular cross section that human finger bones have, and is very flexible. The skin on their wing membranes has more elasticity and so can stretch much more than other mammals.
The wings of bats are much thinner than those of birds, so bats can manoeuvre more quickly and more accurately than birds. It is also delicate, ripping easily.[22] However the tissue of the bat's membrane is able to regrow, such that small tears can heal quickly.[22][23] The surface of their wings is equipped with touch-sensitive receptors on small bumps called Merkel cells, found in most mammals including humans, similarly found on our finger tips. These sensitive areas are different in bats as each bump has a tiny hair in the center,[24] making it even more sensitive and allowing the bat to detect and collect information about the air flowing over its wings, thereby providing feedback to the bat to change its shape of its wing to fly more efficiently.[24] Some bats like the little brown bat can use this dexterious ability where it is able to drink in mid air.[25] Other bats such as the flying fox or fruit bat gently skim the water's surface, then land nearby to lick water from their chest fur.[26] An additional kind of receptor cell is found in the wing membrane of species that use their wings to catch prey. This receptor cell is sensitive to the stretching of the membrane.[24] The cells are concentrated in areas of the membrane where insects hit the wings when the bats capture them.
Other The teeth of microbats resemble insectivorans. They are very sharp to bite through the hardened armor of insects or the skin of fruit.
Mammals have one-way valves in veins to prevent the blood from flowing backwards, but bats also have one-way valves in arteries.
One species of bat has the longest tongue of any mammal relative to its body size. This is beneficial to them in terms of pollination and feeding. Their long narrow tongues can reach deep into the long cup shape of some flowers. When their tongue retracts, it coils up inside their rib cage.[27]
Reproduction Newborn Common Pipistrelle, Pipistrellus pipistrellus. Colony of Mouse-eared bats, Myotis myotis. Most bats have a breeding season, which is in the spring for species living in a temperate climate. Bats may have one to three litters in a season, depending on the species and on environmental conditions such as the availability of food and roost sites. Females generally have one offspring at a time, which could be a result of the mother's need to fly to feed while pregnant. Female bats nurse their youngsters until they are nearly adult size; this is because a young bat cannot forage on its own until its wings are fully developed.
Female bats use a variety of strategies to control the timing of pregnancy and the birth of young, to make delivery coincide with maximum food ability and other ecological factors. Females of some species have delayed fertilization, in which sperm are stored in the reproductive tract for several months after mating. In many such cases, mating occurs in the fall, and fertilization does not occur until the following spring. Other species exhibit delayed implantation, in which the egg is fertilized after mating, but remains free in the reproductive tract until external conditions become favorable for giving birth and caring for the offspring. In yet another strategy, fertilization and implantation both occur but development of the fetus is delayed until favorable conditions prevail. All of these adaptations result in the pup being born during a time of high local production of fruit or insects.
At birth the wings are too small to be used for flight. Young microbats become independent at the age of 6 to 8 weeks, megabats do not until they are four months old.
A single bat can live over 20 years, but the bat population growth is limited by the slow birth rate.[28]
Hunting, feeding, and drinking Newborn bats rely on the milk from their mother’s nipples for sustenance.[29] When they are a few weeks old, bats are expected to fly and hunt on their own. It is up to them to find and catch their prey, along with satisfying their thirst.[30]
Hunting Most bats are nocturnal creatures. Their daylight hours are spent grooming, sleeping, and resting; it is during the nighttime hours that they hunt. The means by which bats navigate while finding and catching their prey in the dark was unknown until the 1790s, when Lazzaro Spallanzani conducted a series of experiments on a group of blind bats. These bats were placed in a room submerged in total darkness, with silk threads strung across the room. Even then, the bats were able to navigate their way through the room. Spallanzani concluded that the bats were not using their eyes to fly through complete darkness, but something else.
Spallanzani decided that bats were able to catch and find their prey through the use of their ears. To prove this theory, Spallanzani plugged the ears of the bats in his experiment. To his pleasure, he found that the bats with plugged ears were not able to fly with the same amount of skill and precision that they were able to without their ears plugged.
Bats seem to use their ears to locate and catch their prey, but how they accomplish this wasn’t discovered until the 1930s, by one Donald R. Griffin. Griffin, who was a biology student at Harvard College at the time, discovered that bats use echolocation to locate and catch their prey. When bats fly, they produce a constant stream of high-pitched sounds that only bats are able to hear. When the sound waves produced by these sounds hit an insect or other animal, the echoes bounce back to the bat, and guide them to the source.[30]
Feeding The majority of food consumed by bats includes insects, fruits and flower nectar, vertebrates and blood.[31] Almost three-fourths of the world’s bats are insect eaters. Each of these bats is able to consume one third of its body weight in insects each night, and several hundred insects in a few hours. This means that a group of one thousand bats could eat four tons of insects each year. If bats were to become extinct, the insect population would reach an alarmingly high number.[32]
The types of insects consumed by bats can be divided into two categories: aerial insects, and ground-dwelling insects.
Aerial insectivores Watching a bat catch and eat an insect is difficult. The action is so fast that all one sees is a bat rapidly change directions, and continue on its way. Scientist Frederick A. Webster discovered how bats catch their prey. In 1960, Webster developed a high-speed camera that was able to take one thousand pictures per second. These photos revealed the fast and precise way in which bats catch insects.[30] Occasionally, a bat will catch an insect in mid-air with its mouth, and eat it in the air. However, more often than not, a bat will use its tail membrane or wings to scoop up the insect and trap it in a sort of “bug net”.[29] Then, the bat will take the insect back to its roost. There, the bat will proceed to eat said insect, often using its tail membrane as a kind of napkin, to prevent its meal from falling to the ground.[31]
Forage gleaners These bats typically fly down and grasp their prey off the ground with their teeth, and take it to a nearby perch to eat it. Generally, these bats don’t use echolocation to locate their prey. Instead, they rely on the sounds produced by the insects. Some make unique sounds, and almost all make some noise while moving through the environment.[29]
Fruits and flower nectar A colony of Great Fruit-eating Bats Fruit-eating, or frugivory, is a specific habit found in two families of bats. Megachiropterans and microchiropterans both include species of bat that feed on fruits. These bats feed on the juices of sweet fruits, and fulfill the needs of some seeds to be dispersed. The fruits preferred by most fruit-eating bats are fleshy and sweet, but not particularly strong smelling or colorful.[29] To get the juice of these fruits, bats pull the fruit off the trees with their teeth, and fly back to their roost with the fruit in their mouth. There, the bat will consume the fruit in a specific way. To do this, the bats crush open the fruit and eat the parts that satisfy their hunger. The remainder of the fruit; the seeds and pulp, are spat onto the ground. These seeds take root and begin to grow into new fruit trees.[32] “Over one hundred and fifty types of plants depend on bats in order to reproduce”.[32]
Some bats prefer the nectar of flowers to insects or other animals. These bats have evolved specifically for this purpose. For example, these bats possess long muzzles and long extrusible tongues covered in fine bristles that aid them in feeding on particular flowers and plants.[29] When they sip the nectar from these flowers, pollen gets stuck to their fur, and is dusted off when the bat takes flight, thus pollinating the plants below them.[32] The rainforest is said to be the most benefitted out off all the biomes that bats live in, because of the large variety of appealing plants.[33] Because of their specific eating habits, nectar-feeding bats are more prone to extinction than any other type of bat.[34] However, according to a study, bats benefit from eating fruits and nectar just as much from eating insects.[35]
Vertebrates Although most bats are not included in this group, there is a small group that comprises the carnivorous bats, these bats feed on other vertebrates, and are considered the “top carnivores of the bat world”.[29] These bats typically eat a variety of animals, but normally consume frogs, lizards, and birds, and sometimes other bats.[32] For example, one vertebrate predator; Trachops cirrhosus, is particularly skilled at catching frogs. These bats locate large groups of frogs by distinguishing their mating calls from other sounds around them. They follow the sounds to the source, and pluck them from the surface of the water with their sharp canine teeth.[29]
There are also several species of bat that feed on fish. These types of bats are found on almost all continents. They use echolocation to detect tiny ripples in the water’s surface to locate fish. From there, the bats swoop down low, inches from the water, and use specially enlarged claws on their hind feet to grab the fish out of the water. The bats then take the fish to a feeding roost and consume the animal.[29]
Blood There are a few species of bat that consume blood exclusively as their diet. This type of diet is referred to as hematophagy, and three species of bat exhibit this behavior. These species include the Common Vampire Bat, the White-winged Vampire Bat, and the Hairy-legged Vampire Bat. The Common Vampire Bat typically consumes the blood of mammals, while the Hairy-legged and White-winged feed on the blood of birds.[36]
Results of eating Bats’ dung, or guano, is so rich in nutrients, that it is mined from caves, bagged, and used by farmers to fertilize their crops. Also, guano was used in the U.S. Civil War to make gunpowder.[32]
There comes a time in the year that some bats will not eat to supply themselves with food for the night, but for the coming months. These bats are beginning to hibernate. To do this, the bat will eat as much food as its body can contain, being as fat as possible. The bat’s body then takes from the supply of fat for energy, but very slowly, because all body activities have slowed down. This supply of fat will last until the spring season arrives.[30]
Drinking Generally, bats drink water. In 1960, Frederic A. Webster discovered how bats are able to acquire this water. To do this, Webster developed a high-speed camera and flashgun that could take one thousand photos per second. Webster's camera captured the bat's method of skimming the surface of a body of water, and lowering its jaw to get just one drop of water. It then skims again to get a second drop of water, and then again to get a third, and so on, until it has had its fill of water. Its precision and control is very fine, and it almost never misses.[30]
Behaviour Most microbats are nocturnal and are active at twilight. A large portion of bats migrate hundreds of kilometres to winter hibernation dens[37], some pass into torpor in cold weather, rousing and feeding when warm weather allows for insects to be active[38]. Others retreat to caves for winter and hibernate for six months.[38] Bats rarely fly in rain as the rain interferes with their echo location, and they are unable to locate their food.
The social structure of bats varies, with some bats leading a solitary life and others living in caves colonized by more than a million bats[39]. The fission-fusion social structure is seen among several species of bats. The term "fusion" refers to a large numbers of bats that congregate together in one roosting area and "fission" refers to breaking up and the mixing of subgroups, with individual bats switching roosts with others and often ending up in different trees and with different roostmates.
Studies also show that bats make all kinds of sounds to communicate with others. Scientists in the field have listened to bats and have been able to identify some sounds with some behaviour bats will make after the sounds are made[39].
70% of bat species are insectivorous, locating their prey by means of echolocation. Of the remainder, most feed on fruits[40]. Only three species sustain themselves with blood. Some species even prey on vertebrates: these are the leaf-nosed bats (Phyllostomidae) of Central America and South America, and the two bulldog bat (Noctilionidae) species, which feed on fish. At least two species of bat are known to feed on bats: the Spectral Bat, also known as the American False Vampire bat, and the Ghost Bat of Australia[40]. One species, the Greater Noctule bat, catches and eats small birds in the air.
Predators of bats include Bat Hawks and Bat Falcons.
Conservation efforts Through conservancy efforts, such as the Organization for Bat Conservation, bats are becoming better understood and people beginning to understand the crucial role bats play in insect control and pollination.
In the United Kingdom all bats are protected under the Wildlife and Countryside Acts, and even disturbing a bat or its roost can be punished with a heavy fine.
In Sarawak, Malaysia bats are protected species under the Wildlife Protection Ordinance 1998 (see Malaysian Wildlife Law). The large Naked bat (see Mammals of Borneo) and Greater Nectar bat are consumed by the local communities.
Bats can be a tourist attraction. The Congress Avenue Bridge in Austin, Texas is the summer home to North America's largest urban bat colony, an estimated 1,500,000 Mexican free-tailed bats, which eat an estimated 10,000 to 30,000 pounds of insects each night. An estimated 100,000 tourists per year visit the bridge at twilight to watch the bats leave the roost.
Threats A little brown bat with white nose syndrome. While conservation efforts are in place to protect bats, many threats still remain.
White nose syndrome Main article: White nose syndrome White nose syndrome is a condition associated with the deaths of more than a million bats in the Northeastern United States.[41] The disease is named after a white fungus found growing on the muzzles, ears, and wings of some afflicted bats, but it is not known if the fungus is the primary cause of the disease or is merely an opportunistic infection.[42] Mortality rates of 90–100% have been observed in some caves.[42] At least six species of hibernating bats are affected, including the endangered Indiana bat.[43] Because the affected species have a long lifespan and a low birth rate of only about one offspring per year, it is not expected that populations will recover quickly.[43]
Wind turbines The lungs of bats are typical mammalian lungs, and unlike the lungs of birds it has been hypothesized they are more sensitive to sudden air pressure changes in their immediate vicinity such as wind turbines, and are more liable to rupture them to explain their apparent higher rate of mortality rate with such devices.[44] Bats suffer a higher death rate than birds in the neighborhood of wind turbines[45][46][47] since there are no signs of external trauma, the cause has been hypothesized to be a greater sensitivity to sudden pressure fluctuations in the mammalian lung than in that of birds.[48] In addition, it has been suggested that bats are attracted to these structures, perhaps seeking roosts, and thereby increasing the death rate.[44]
Role in the transmission of pathogens Bats are natural reservoir for a large number of zoonotic pathogens[49] including rabies,[50] severe acute respiratory syndrome (SARS),[51] Henipavirus (i.e. Nipah virus and Hendra virus)[52] and possibly ebola virus[53].[54] Their high mobility, broad distribution, and social behaviour (communal roosting, fission-fusion social structure) make bats favourable hosts and vectors of disease. Many species also appear to have a high tolerance for harbouring pathogens and often do not develop disease while infected.
In regions where rabies is endemic, only 0.5% of bats carry the disease. However, of the few cases of rabies reported in the United States every year not caused by dogs, most are caused by bat bites.[55] Those that are rabid may be clumsy, disoriented, and unable to fly, which makes it more likely that they will come into contact with humans. Although one should not have an unreasonable fear of bats, one should avoid handling them or having them in one's living space, as with any wild animal. If a bat is found in living quarters near a child, mentally handicapped person, intoxicated person, sleeping person, or pet, the person or pet should receive immediate medical attention for rabies. Bats have very small teeth and can bite a sleeping person without being felt. There is evidence that it is possible for the bat rabies virus to infect victims purely through airborne transmission, without direct physical contact of the victim with the bat itself.[56][57]
If a bat is found in a house and the possibility of exposure cannot be ruled out, the bat should be sequestered and an animal control officer called immediately, so that the bat can be analysed. This also applies if the bat is found dead. If it is certain that nobody has been exposed to the bat, it should be removed from the house. The best way to do this is to close all the doors and windows to the room except one that opens to the outside. The bat should soon leave.
Due to the risk of rabies and also due to health problems related to their faecal droppings (guano), bats should be excluded from inhabited parts of houses. The Center for Disease Control and Prevention provides full detailed information on all aspects of bat management, including how to capture a bat, what to do in case of exposure, and how to bat-proof a house humanely.[58] In certain countries, such as the United Kingdom, it is illegal to handle bats without a license.
Where rabies is not endemic, as throughout most of Western Europe, small bats can be considered harmless. Larger bats can give a nasty bite. They should be treated with the respect due to any wild animal.
Bat mythology "Nightwing," a work of art by Dale Whistler in Austin, Texas. The bat is sacred in Tonga and is often considered the physical manifestation of a separable soul[citation needed]. Bats are closely associated with vampires, who are said to be able to shapeshift into bats, fog, or wolves. Bats are also a symbol of ghosts, death, and disease. Among some Native Americans, such as the Creek, Cherokee and Apache, the bat is a trickster spirit.
Chinese lore claims the bat is a symbol of longevity and happiness, and is similarly lucky in Poland and geographical Macedonia and among the Kwakiutl and Arabs. The bat is also a heraldic animal of the Spanish autonomous community of Valencia.
Pre-Columbian cultures associated animals with gods and often displayed them in art. The Moche people depicted bats in their ceramics.[59]
In Western Culture, the bat is often a symbol of the night and its foreboding nature. The bat is a primary animal associated with fictional characters of the night, both villains like Dracula and heroes like Batman. The association of the fear of the night with the animal was treated as a literary challenge by Kenneth Oppel, who created a best selling series of novels, beginning with Silverwing, which feature bats as the central heroic figures much as anthropomorphized rabbits were the central figures to the classic novel Watership Down.
An old wives' tale has it that bats will entangle themselves in people's hair. One likely source of this belief is that insect-eating bats seeking prey may dive erratically toward people, who attract mosquitoes and gnats, leading the squeamish to believe that the bats are trying to get in their hair.
- Megachiroptera (megabats)
- Microchiroptera (microbats/echolocating bats)
- Microbats use echolocation: megabats do not with the exception of Rousettus and relatives.
- Microbats lack the claw at the second toe of the forelimb.
- The ears of microbats do not close to form a ring: the edges are separated from each other at the base of the ear.
- Microbats lack underfur: they are either naked or have guard hairs.
The phylogenetic relationships of the different groups of bats have been the subject of much debate. The traditional subdivision between Megachiroptera and Microchiroptera reflects the view that these groups of bats have evolved independently of each other for a long time, from a common ancestor that was already capable of flight. This hypothesis recognized differences between microbats and megabats and acknowledged that flight has only evolved once in mammals. Most molecular biological evidence supports the view that bats form a single or monophyletic group.[5]
Researchers have proposed alternate views of chiropteran phylogeny and classification, but more research is needed.
Genetic evidence indicates that megabats originated during the early Eocene and should be placed within the four major lines of microbats.
Consequently, two new suborders based on molecular data have been proposed. The new suborder Yinpterochiroptera includes the Pteropodidae or megabat family as well as the Rhinolophidae, Megadermatidae, and Rhinopomatidae families. The new suborder Yangochiroptera includes all the remaining families of bats (all of which use laryngeal echolocation). These two new suborders are strongly supported by statistical tests. Teeling (2005) found 100% bootstrap support in all maximum likelihood analyses for the division of Chiroptera into these two modified suborders. This conclusion is further supported by a fifteen-base pair deletion in BRCA1 and a seven-base pair deletion in PLCB4 present in all Yangochiroptera and absent in all Yinpterochiroptera.[6] The Chiropteran phylogeny based on molecular evidence is controversial because microbat paraphyly implies that one of two seemingly unlikely hypotheses occurred. The first suggests that laryngeal echolocation evolved twice in Chiroptera, once in Yangochiroptera and once in the rhinolophoids.[7][8] The second proposes that laryngeal echolocation had a single origin in Chiroptera, was subsequently lost in the family Pteropodidae (all megabats), and later evolved as a system of tongue-clicking in the genus Rousettus.[9]
Common Pipistrelle, Pipistrellus pipistrellus. Analyses of the sequence of the "vocalization" gene, FoxP2 was inconclusive of whether laryngeal echolocation was secondarily lost in the pteropodids or independently gained in the echolocating lineages[10]. However, analyses of the "hearing" gene, Prestin seemed to favor the independent gain in echolocating species rather than a secondary loss in the pteropodids.[11]
In addition to Yinpterochiroptera and Yangochiroptera, the names Pteropodiformes and Vespertilioniformes have also been proposed for these suborders.[12][13] Under this new proposed nomenclature, the suborder Pteropodiformes includes all extant bat families more closely related to the genus Pteropus than the genus Vespertilio, while the suborder Vespertilioniformes includes all extant bat families more closely related to the genus Vespertilio than to the genus Pteropus.
In the 1980s, a hypothesis based on morphological evidence was offered that stated that the Megachiroptera evolved flight separately from the Microchiroptera. The so-called flying primates theory proposed that when adaptations to flight are removed, the Megachiroptera are allied to primates by anatomical features that are not shared with Microchiroptera. One example is that the brains of megabats show a number of advanced characteristics that link them to primates. Although recent genetic studies support the monophyly of bats,[14] debate continues as to the meaning of available genetic and morphological evidence.[15]
Little fossil evidence is available to help map the evolution of bats, since their small, delicate skeletons do not fossilize very well. However a Late Cretaceous tooth from South America resembles that of an early Microchiropteran bat. The oldest known definitely identified bat fossils, such as Icaronycteris, Archaeonycteris, Palaeochiropteryx and Hassianycteris, are from the early Eocene period, 52.5 million years ago[5]. These fossil bats were already very similar to modern microbats. Archaeopteropus, formerly classified as the earliest known megachiropteran, is now classified as a microchiropteran.
Bats were formerly grouped in the superorder Archonta along with the treeshrews (Scandentia), colugos (Dermoptera), and the primates, because of the apparent similarities between Megachiroptera and such mammals. Genetic studies have now placed bats in the superorder Laurasiatheria along with carnivorans, pangolins, odd-toed ungulates, even-toed ungulates, and cetaceans.[1]
"Chiroptera" from Ernst Haeckel's Kunstformen der Natur, 1904 The traditional classification of bats is:
- Order Chiroptera
- Suborder Megachiroptera (megabats)
- Suborder Microchiroptera (microbats)
- Superfamily Emballonuroidea
- Emballonuridae (Sac-winged or Sheath-tailed bats)
- Superfamily Molossoidea
- Superfamily Nataloidea
- Superfamily Noctilionoidea
- Mormoopidae (Ghost-faced or Moustached bats)
- Mystacinidae (New Zealand short-tailed bats)
- Noctilionidae (Bulldog bats or Fisherman bats)
- Phyllostomidae (Leaf-nosed bats)
- Superfamily Rhinolophoidea
- Megadermatidae (False vampires)
- Nycteridae (Hollow-faced or Slit-faced bats)
- Rhinolophidae (Horseshoe bats)
- Superfamily Rhinopomatoidea
- Craseonycteridae (Bumblebee Bat or Kitti's Hog-nosed Bat)
- Rhinopomatidae (Mouse-tailed bats)
- Superfamily Vespertilionoidea
- Vespertilionidae (Vesper bats or Evening bats)
- Superfamily Emballonuroidea
Fossil bats There are few fossilized remains of bats, as they are terrestrial and light-boned. An Eocene bat, Onychonycteris finneyi, was found in the fifty-two-million-year-old Green River Formation in South Dakota, United States, in 2004 and was added as a new genus and placed in a new family when published in Nature in 2008.[16] It had characteristics indicating that it could fly, yet the well-preserved skeleton showed that the cochlea of the inner ear lacked development needed to support the greater hearing abilities of modern bats. This provided evidence that flight in bats developed well before echolocation. The team that found the remains of this species, named Onychonycteris finneyi, recognized that it lacked ear and throat features present not only in echolocating bats today, but also in other known prehistoric species. Fossil remains of another Eocene bat, Icaronycteris, were found in 1960.
The appearance and flight movement of bats 52.5 million years ago were different from those of bats today. Onychonycteris had claws on all five of its fingers, whereas modern bats have at most two claws appearing on two digits of each hand. It also had longer hind legs and shorter forearms, similar to climbing mammals that hang under branches such as sloths and gibbons. This palm-sized bat had broad, short wings suggesting that it could not fly as fast or as far as later bat species. Instead of flapping its wings continuously while flying, Onychonycteris likely alternated between flaps and glides while in the air. Such physical characteristics suggest that this bat did not fly as much as modern bats do, rather flying from tree to tree and spending most of its waking day climbing or hanging on the branches of trees.[17]
Anatomy Skeleton of a Greater Mouse-eared Bat (Myotis myotis). Echolocation Spectrogram of Pipistrellus Bat vocalizations. Detail is shown as the pulse duty cycle increases during a close approach to prey. The bat appears to use a hybrid pulse which combines a sharp falling frequency chirp with an extended constant frequency tail. Such a waveform may offer combined benefits of range estimation as well as Doppler shift detection. Spectrogram generated with Fatpigdog's PC based Real Time FFT Spectrum Analyzer. Pipistrellus Pulses Recording of Pipistrellus bat approaching its prey. Problems listening to this file? See media help. Bat echolocation is a perceptual system where ultrasonic sounds are emitted specifically to produce echoes. By comparing the outgoing pulse with the returning echoes the brain and auditory nervous system can produce detailed images of the bat's surroundings. This allows bats to detect, localize and even classify their prey in complete darkness. At 130 decibels in intensity, bat calls are some of the most intense airborne animal sounds.[18]
To clearly distinguish returning information, bats must be able to separate their calls from the echoes they receive. Microbats use two distinct approaches.
1.Low Duty Cycle Echolocation: Bats can separate their calls and returning echos by time. Bats that use this approach time their short calls to finish before echoes return. This is important because these bats contract their middle ear muscles when emitting a call so that they can avoid deafening themselves. The time interval between call and echo allows them to relax these muscles so they can clearly hear the returning echo.[19] The delay of the returning echos provide the bat with the ability to estimate range to their prey.
2. High Duty Cycle Echolocation: Bats emit a continuous call and separate pulse and echo in frequency. The ears of these bats are sharply tuned to a specific frequency range. They emit calls outside of this range to avoid self-deafening. They then receive echoes back at the finely tuned frequency range by taking advantage of the Doppler shift of their motion in flight. The Doppler shift of the returning echos yield information relating to the motion and location of the bat's prey. These bats must deal with changes in the Doppler shift due to changes in their flight speed. They have adapted to change their pulse emission frequency in relation to their flight speed so echoes still return in the optimal hearing range.[20]
The new Yinpterochiroptera and Yangochiroptera classification of bats that are supported by molecular evidence, suggest two possibilities for the evolution of echolocation. It may have been gained once in a common ancestor of all bats and was then subsequently lost in the Old World fruit bats, only to be regained in the Horse-Shoe bats; or echolocation was evolved independent in both the Yinpterochiroptera and Yangochirpotera lineages.[21]
Two groups of moths exploit a bat sense to echolocate: tiger moths produce ultrasonic signals to warn the bats that they (the moths) are chemically protected or aposematic. This was once thought to be the biological equivalent of "radar jamming", but this theory has yet to be confirmed. The moths Noctuidae have a hearing organ called a tympanum, which responds to an incoming bat signal by causing the moth's flight muscles to twitch erratically, sending the moth into random evasive manoeuvres.
Eyes Although the eyes of most microbat species are small and poorly developed, leading to poor visual acuity, none of them are blind. Vision is used to navigate microbats especially for long distances when beyond the range of echolocation. It has even been discovered that some species are able to detect ultraviolet light. They also have a high quality sense of smell and hearing. Bats hunt at night to avoid competition with birds, and travel large distances at most 800 km, in their search for food.[2]
Wings Thermographic image of a bat using trapped air as insulation. The finger bones of bats are much more flexible than those of other mammals. One reason is that the cartilage in their fingers lacks calcium and other minerals nearer the tips, increasing their ability to bend without splintering. The cross-section of the finger bone is also flattened compared to the circular cross section that human finger bones have, and is very flexible. The skin on their wing membranes has more elasticity and so can stretch much more than other mammals.
The wings of bats are much thinner than those of birds, so bats can manoeuvre more quickly and more accurately than birds. It is also delicate, ripping easily.[22] However the tissue of the bat's membrane is able to regrow, such that small tears can heal quickly.[22][23] The surface of their wings is equipped with touch-sensitive receptors on small bumps called Merkel cells, found in most mammals including humans, similarly found on our finger tips. These sensitive areas are different in bats as each bump has a tiny hair in the center,[24] making it even more sensitive and allowing the bat to detect and collect information about the air flowing over its wings, thereby providing feedback to the bat to change its shape of its wing to fly more efficiently.[24] Some bats like the little brown bat can use this dexterious ability where it is able to drink in mid air.[25] Other bats such as the flying fox or fruit bat gently skim the water's surface, then land nearby to lick water from their chest fur.[26] An additional kind of receptor cell is found in the wing membrane of species that use their wings to catch prey. This receptor cell is sensitive to the stretching of the membrane.[24] The cells are concentrated in areas of the membrane where insects hit the wings when the bats capture them.
Other The teeth of microbats resemble insectivorans. They are very sharp to bite through the hardened armor of insects or the skin of fruit.
Mammals have one-way valves in veins to prevent the blood from flowing backwards, but bats also have one-way valves in arteries.
One species of bat has the longest tongue of any mammal relative to its body size. This is beneficial to them in terms of pollination and feeding. Their long narrow tongues can reach deep into the long cup shape of some flowers. When their tongue retracts, it coils up inside their rib cage.[27]
Reproduction Newborn Common Pipistrelle, Pipistrellus pipistrellus. Colony of Mouse-eared bats, Myotis myotis. Most bats have a breeding season, which is in the spring for species living in a temperate climate. Bats may have one to three litters in a season, depending on the species and on environmental conditions such as the availability of food and roost sites. Females generally have one offspring at a time, which could be a result of the mother's need to fly to feed while pregnant. Female bats nurse their youngsters until they are nearly adult size; this is because a young bat cannot forage on its own until its wings are fully developed.
Female bats use a variety of strategies to control the timing of pregnancy and the birth of young, to make delivery coincide with maximum food ability and other ecological factors. Females of some species have delayed fertilization, in which sperm are stored in the reproductive tract for several months after mating. In many such cases, mating occurs in the fall, and fertilization does not occur until the following spring. Other species exhibit delayed implantation, in which the egg is fertilized after mating, but remains free in the reproductive tract until external conditions become favorable for giving birth and caring for the offspring. In yet another strategy, fertilization and implantation both occur but development of the fetus is delayed until favorable conditions prevail. All of these adaptations result in the pup being born during a time of high local production of fruit or insects.
At birth the wings are too small to be used for flight. Young microbats become independent at the age of 6 to 8 weeks, megabats do not until they are four months old.
A single bat can live over 20 years, but the bat population growth is limited by the slow birth rate.[28]
Hunting, feeding, and drinking Newborn bats rely on the milk from their mother’s nipples for sustenance.[29] When they are a few weeks old, bats are expected to fly and hunt on their own. It is up to them to find and catch their prey, along with satisfying their thirst.[30]
Hunting Most bats are nocturnal creatures. Their daylight hours are spent grooming, sleeping, and resting; it is during the nighttime hours that they hunt. The means by which bats navigate while finding and catching their prey in the dark was unknown until the 1790s, when Lazzaro Spallanzani conducted a series of experiments on a group of blind bats. These bats were placed in a room submerged in total darkness, with silk threads strung across the room. Even then, the bats were able to navigate their way through the room. Spallanzani concluded that the bats were not using their eyes to fly through complete darkness, but something else.
Spallanzani decided that bats were able to catch and find their prey through the use of their ears. To prove this theory, Spallanzani plugged the ears of the bats in his experiment. To his pleasure, he found that the bats with plugged ears were not able to fly with the same amount of skill and precision that they were able to without their ears plugged.
Bats seem to use their ears to locate and catch their prey, but how they accomplish this wasn’t discovered until the 1930s, by one Donald R. Griffin. Griffin, who was a biology student at Harvard College at the time, discovered that bats use echolocation to locate and catch their prey. When bats fly, they produce a constant stream of high-pitched sounds that only bats are able to hear. When the sound waves produced by these sounds hit an insect or other animal, the echoes bounce back to the bat, and guide them to the source.[30]
Feeding The majority of food consumed by bats includes insects, fruits and flower nectar, vertebrates and blood.[31] Almost three-fourths of the world’s bats are insect eaters. Each of these bats is able to consume one third of its body weight in insects each night, and several hundred insects in a few hours. This means that a group of one thousand bats could eat four tons of insects each year. If bats were to become extinct, the insect population would reach an alarmingly high number.[32]
The types of insects consumed by bats can be divided into two categories: aerial insects, and ground-dwelling insects.
Aerial insectivores Watching a bat catch and eat an insect is difficult. The action is so fast that all one sees is a bat rapidly change directions, and continue on its way. Scientist Frederick A. Webster discovered how bats catch their prey. In 1960, Webster developed a high-speed camera that was able to take one thousand pictures per second. These photos revealed the fast and precise way in which bats catch insects.[30] Occasionally, a bat will catch an insect in mid-air with its mouth, and eat it in the air. However, more often than not, a bat will use its tail membrane or wings to scoop up the insect and trap it in a sort of “bug net”.[29] Then, the bat will take the insect back to its roost. There, the bat will proceed to eat said insect, often using its tail membrane as a kind of napkin, to prevent its meal from falling to the ground.[31]
Forage gleaners These bats typically fly down and grasp their prey off the ground with their teeth, and take it to a nearby perch to eat it. Generally, these bats don’t use echolocation to locate their prey. Instead, they rely on the sounds produced by the insects. Some make unique sounds, and almost all make some noise while moving through the environment.[29]
Fruits and flower nectar A colony of Great Fruit-eating Bats Fruit-eating, or frugivory, is a specific habit found in two families of bats. Megachiropterans and microchiropterans both include species of bat that feed on fruits. These bats feed on the juices of sweet fruits, and fulfill the needs of some seeds to be dispersed. The fruits preferred by most fruit-eating bats are fleshy and sweet, but not particularly strong smelling or colorful.[29] To get the juice of these fruits, bats pull the fruit off the trees with their teeth, and fly back to their roost with the fruit in their mouth. There, the bat will consume the fruit in a specific way. To do this, the bats crush open the fruit and eat the parts that satisfy their hunger. The remainder of the fruit; the seeds and pulp, are spat onto the ground. These seeds take root and begin to grow into new fruit trees.[32] “Over one hundred and fifty types of plants depend on bats in order to reproduce”.[32]
Some bats prefer the nectar of flowers to insects or other animals. These bats have evolved specifically for this purpose. For example, these bats possess long muzzles and long extrusible tongues covered in fine bristles that aid them in feeding on particular flowers and plants.[29] When they sip the nectar from these flowers, pollen gets stuck to their fur, and is dusted off when the bat takes flight, thus pollinating the plants below them.[32] The rainforest is said to be the most benefitted out off all the biomes that bats live in, because of the large variety of appealing plants.[33] Because of their specific eating habits, nectar-feeding bats are more prone to extinction than any other type of bat.[34] However, according to a study, bats benefit from eating fruits and nectar just as much from eating insects.[35]
Vertebrates Although most bats are not included in this group, there is a small group that comprises the carnivorous bats, these bats feed on other vertebrates, and are considered the “top carnivores of the bat world”.[29] These bats typically eat a variety of animals, but normally consume frogs, lizards, and birds, and sometimes other bats.[32] For example, one vertebrate predator; Trachops cirrhosus, is particularly skilled at catching frogs. These bats locate large groups of frogs by distinguishing their mating calls from other sounds around them. They follow the sounds to the source, and pluck them from the surface of the water with their sharp canine teeth.[29]
There are also several species of bat that feed on fish. These types of bats are found on almost all continents. They use echolocation to detect tiny ripples in the water’s surface to locate fish. From there, the bats swoop down low, inches from the water, and use specially enlarged claws on their hind feet to grab the fish out of the water. The bats then take the fish to a feeding roost and consume the animal.[29]
Blood There are a few species of bat that consume blood exclusively as their diet. This type of diet is referred to as hematophagy, and three species of bat exhibit this behavior. These species include the Common Vampire Bat, the White-winged Vampire Bat, and the Hairy-legged Vampire Bat. The Common Vampire Bat typically consumes the blood of mammals, while the Hairy-legged and White-winged feed on the blood of birds.[36]
Results of eating Bats’ dung, or guano, is so rich in nutrients, that it is mined from caves, bagged, and used by farmers to fertilize their crops. Also, guano was used in the U.S. Civil War to make gunpowder.[32]
There comes a time in the year that some bats will not eat to supply themselves with food for the night, but for the coming months. These bats are beginning to hibernate. To do this, the bat will eat as much food as its body can contain, being as fat as possible. The bat’s body then takes from the supply of fat for energy, but very slowly, because all body activities have slowed down. This supply of fat will last until the spring season arrives.[30]
Drinking Generally, bats drink water. In 1960, Frederic A. Webster discovered how bats are able to acquire this water. To do this, Webster developed a high-speed camera and flashgun that could take one thousand photos per second. Webster's camera captured the bat's method of skimming the surface of a body of water, and lowering its jaw to get just one drop of water. It then skims again to get a second drop of water, and then again to get a third, and so on, until it has had its fill of water. Its precision and control is very fine, and it almost never misses.[30]
Behaviour Most microbats are nocturnal and are active at twilight. A large portion of bats migrate hundreds of kilometres to winter hibernation dens[37], some pass into torpor in cold weather, rousing and feeding when warm weather allows for insects to be active[38]. Others retreat to caves for winter and hibernate for six months.[38] Bats rarely fly in rain as the rain interferes with their echo location, and they are unable to locate their food.
The social structure of bats varies, with some bats leading a solitary life and others living in caves colonized by more than a million bats[39]. The fission-fusion social structure is seen among several species of bats. The term "fusion" refers to a large numbers of bats that congregate together in one roosting area and "fission" refers to breaking up and the mixing of subgroups, with individual bats switching roosts with others and often ending up in different trees and with different roostmates.
Studies also show that bats make all kinds of sounds to communicate with others. Scientists in the field have listened to bats and have been able to identify some sounds with some behaviour bats will make after the sounds are made[39].
70% of bat species are insectivorous, locating their prey by means of echolocation. Of the remainder, most feed on fruits[40]. Only three species sustain themselves with blood. Some species even prey on vertebrates: these are the leaf-nosed bats (Phyllostomidae) of Central America and South America, and the two bulldog bat (Noctilionidae) species, which feed on fish. At least two species of bat are known to feed on bats: the Spectral Bat, also known as the American False Vampire bat, and the Ghost Bat of Australia[40]. One species, the Greater Noctule bat, catches and eats small birds in the air.
Predators of bats include Bat Hawks and Bat Falcons.
Conservation efforts Through conservancy efforts, such as the Organization for Bat Conservation, bats are becoming better understood and people beginning to understand the crucial role bats play in insect control and pollination.
In the United Kingdom all bats are protected under the Wildlife and Countryside Acts, and even disturbing a bat or its roost can be punished with a heavy fine.
In Sarawak, Malaysia bats are protected species under the Wildlife Protection Ordinance 1998 (see Malaysian Wildlife Law). The large Naked bat (see Mammals of Borneo) and Greater Nectar bat are consumed by the local communities.
Bats can be a tourist attraction. The Congress Avenue Bridge in Austin, Texas is the summer home to North America's largest urban bat colony, an estimated 1,500,000 Mexican free-tailed bats, which eat an estimated 10,000 to 30,000 pounds of insects each night. An estimated 100,000 tourists per year visit the bridge at twilight to watch the bats leave the roost.
Threats A little brown bat with white nose syndrome. While conservation efforts are in place to protect bats, many threats still remain.
White nose syndrome Main article: White nose syndrome White nose syndrome is a condition associated with the deaths of more than a million bats in the Northeastern United States.[41] The disease is named after a white fungus found growing on the muzzles, ears, and wings of some afflicted bats, but it is not known if the fungus is the primary cause of the disease or is merely an opportunistic infection.[42] Mortality rates of 90–100% have been observed in some caves.[42] At least six species of hibernating bats are affected, including the endangered Indiana bat.[43] Because the affected species have a long lifespan and a low birth rate of only about one offspring per year, it is not expected that populations will recover quickly.[43]
Wind turbines The lungs of bats are typical mammalian lungs, and unlike the lungs of birds it has been hypothesized they are more sensitive to sudden air pressure changes in their immediate vicinity such as wind turbines, and are more liable to rupture them to explain their apparent higher rate of mortality rate with such devices.[44] Bats suffer a higher death rate than birds in the neighborhood of wind turbines[45][46][47] since there are no signs of external trauma, the cause has been hypothesized to be a greater sensitivity to sudden pressure fluctuations in the mammalian lung than in that of birds.[48] In addition, it has been suggested that bats are attracted to these structures, perhaps seeking roosts, and thereby increasing the death rate.[44]
Role in the transmission of pathogens Bats are natural reservoir for a large number of zoonotic pathogens[49] including rabies,[50] severe acute respiratory syndrome (SARS),[51] Henipavirus (i.e. Nipah virus and Hendra virus)[52] and possibly ebola virus[53].[54] Their high mobility, broad distribution, and social behaviour (communal roosting, fission-fusion social structure) make bats favourable hosts and vectors of disease. Many species also appear to have a high tolerance for harbouring pathogens and often do not develop disease while infected.
In regions where rabies is endemic, only 0.5% of bats carry the disease. However, of the few cases of rabies reported in the United States every year not caused by dogs, most are caused by bat bites.[55] Those that are rabid may be clumsy, disoriented, and unable to fly, which makes it more likely that they will come into contact with humans. Although one should not have an unreasonable fear of bats, one should avoid handling them or having them in one's living space, as with any wild animal. If a bat is found in living quarters near a child, mentally handicapped person, intoxicated person, sleeping person, or pet, the person or pet should receive immediate medical attention for rabies. Bats have very small teeth and can bite a sleeping person without being felt. There is evidence that it is possible for the bat rabies virus to infect victims purely through airborne transmission, without direct physical contact of the victim with the bat itself.[56][57]
If a bat is found in a house and the possibility of exposure cannot be ruled out, the bat should be sequestered and an animal control officer called immediately, so that the bat can be analysed. This also applies if the bat is found dead. If it is certain that nobody has been exposed to the bat, it should be removed from the house. The best way to do this is to close all the doors and windows to the room except one that opens to the outside. The bat should soon leave.
Due to the risk of rabies and also due to health problems related to their faecal droppings (guano), bats should be excluded from inhabited parts of houses. The Center for Disease Control and Prevention provides full detailed information on all aspects of bat management, including how to capture a bat, what to do in case of exposure, and how to bat-proof a house humanely.[58] In certain countries, such as the United Kingdom, it is illegal to handle bats without a license.
Where rabies is not endemic, as throughout most of Western Europe, small bats can be considered harmless. Larger bats can give a nasty bite. They should be treated with the respect due to any wild animal.
Bat mythology "Nightwing," a work of art by Dale Whistler in Austin, Texas. The bat is sacred in Tonga and is often considered the physical manifestation of a separable soul[citation needed]. Bats are closely associated with vampires, who are said to be able to shapeshift into bats, fog, or wolves. Bats are also a symbol of ghosts, death, and disease. Among some Native Americans, such as the Creek, Cherokee and Apache, the bat is a trickster spirit.
Chinese lore claims the bat is a symbol of longevity and happiness, and is similarly lucky in Poland and geographical Macedonia and among the Kwakiutl and Arabs. The bat is also a heraldic animal of the Spanish autonomous community of Valencia.
Pre-Columbian cultures associated animals with gods and often displayed them in art. The Moche people depicted bats in their ceramics.[59]
In Western Culture, the bat is often a symbol of the night and its foreboding nature. The bat is a primary animal associated with fictional characters of the night, both villains like Dracula and heroes like Batman. The association of the fear of the night with the animal was treated as a literary challenge by Kenneth Oppel, who created a best selling series of novels, beginning with Silverwing, which feature bats as the central heroic figures much as anthropomorphized rabbits were the central figures to the classic novel Watership Down.
An old wives' tale has it that bats will entangle themselves in people's hair. One likely source of this belief is that insect-eating bats seeking prey may dive erratically toward people, who attract mosquitoes and gnats, leading the squeamish to believe that the bats are trying to get in their hair.
9/6/10 Walrus
Many people find the walrus to be one of the most fascinating animals in the world. There is no denying what it is when you see those two long tusks in front of the face.
They have a long history of living in the Arctic regions, surviving in the cold water and on the ice. They have long been a source of food for the people of the Arctic but these people find a use for the entire walrus so they are very respectful in the manner that they use it.
The walrus is a very large animal and one that is believed to have evolved millions of years ago from a land creature.
Walruses feature front and back flippers that help them to swim as well as to move around on land. Due to their large size, a walrus is typically seen moving around at about 4 miles per hour. When necessary they can move at a speed of up to 20 miles per hour for short periods of time.
Walrus Research
There is still plenty that we don’t know about the walrus. Even though they have been researched for a very long time, too much of what they do isn’t well observed by humans. This is due to the isolated regions in which they live. Many things have been learned by observing the walruses that are in captivity. Yet we have to remember that they may not be the same as what would occur in the wild.
Humans and Walruses
The feeding habits of the walrus are very interesting. They consume foods from the bottom of the water including mollusks such as clams. They have also been known to feed on seals in the area when they need to. Due to the large size of these animals they have to consume large amounts of food each day. Generally that will be about 6% of their overall body weight.
Walrus Social Structure
The females are very protective of their young. They take care of them for about two years before they go out on their own. They bonding process between them is amazing. All of the walruses though seem to have a high level of communication. They also have a desire for physical contact with each other. It is for this reason that they have a very detailed social structure.
google_protectAndRun("ads_core.google_render_ad", google_handleError, google_render_ad); They form very large herds that have a hierarchy that is set up overall as well as for sub groups. Due to the many changes that occur in the life of a walrus they can move from one herd to the next. For example males are separate from females and those with offspring to care for are separate herds for that period of time as well.
Walrus Endangered
In the past the walrus has been in jeopardy of extinction due to low numbers. However, the early conservation efforts such as a preventing the sells of ivory have helped them to make a come back. They aren’t considered to be at risk at this time. However, they are still carefully watched to help ensure that the numbers don’t start to go down enough for interventions to be necessary.
Walruses. Image courtesy of NOAA.
Walruses and Global Warming
We also have to consider the fact that global warming is a huge problem for the walrus. They depend on those layers of ice to offer them a place to rest. It is also on the ice where the young are born. Since the people that live in the area of the walrus tend to be protective of them and to depend on them for meat, they don’t often engage in behaviors that will harm them such as releasing harmful chemicals into the water where they live.
Facts about Walruses google_protectAndRun("ads_core.google_render_ad", google_handleError, google_render_ad); How much do you really know about the walrus? Chances are there is plenty about them that you haven’t heard about before. As you read these walrus facts you can be confident that your knowledge about them is going to continue to expand. The name of the walrus means tooth walking sea horse.
The tusks of a full grown walrus can weight over 3 pounds each. Each one features from 400 to 700 whiskers. From a distance the walrus appears to be without fur. However, the entire body is covered with a very thin layer of it. The blubber, which is the layers of fat, on a walrus can be more than 5 inches thick.
A walrus can remain under water for up to 30 minutes before coming up for air. During migration they can travel up to 1,800 miles. The females tend to migrate further than the males. They can stand very cold water that is as low as -31 degrees Fahrenheit. When a calf is very young it will ride on the back of its mother in the water. However, it does know how to swim on its own. This method of movement is for protection and for bonding.
One of the leading causes of death for the walrus is due to various types of parasites in the water. They are able to cause problems for the skin as well as internal infections that shut down the normal functions of these animals. Males often kill each other during their fight for the right to mate or in an effort to move up the social status ladder. Females often keep their young underneath them to prevent them from being crushed by other adults in the area.
The skin of a walrus is very thick. This offers it protection from the extremely cold water as well as from many of the different predators out there. Many people are amused by the fact that the walrus can change colors. It has to do with their skin and their body temperatures. This is all due to the fact that their blood vessels change in size when it is cold versus when it is warmer. For example when it basks in the sun the skin turns red due to the amount of blood that rushes to the skin.
The walrus spends the cold winter months over the Bering Sea. It is common for them to pass through the Bering Strait during their migration patterns. One of the most amazing things about the walrus is that they are able to sleep while they are swimming! This is possible due to the air sacs that are located in the throat region.
There is only one species of walrus which is quite interesting. Most animals out there have many species so this is a fact that helps to identify them as unique in the eyes of researchers as well. Many people don’t realize that the walrus molts. This occurs in June or July as they no longer need their heavy winter coat.
When a walrus needs to break ice, it will do so by slamming its head against it. Then it will use the tusks to make the hole in the ice as large as it needs to. This process allows them to have breathing holes so they can stay under water for longer periods of time. They have to come up for air, but not all the way to the surface. For a very long time it was unknown how they were able to stay under water for so long. Now it is known that they are getting air but just from another source.
They have a long history of living in the Arctic regions, surviving in the cold water and on the ice. They have long been a source of food for the people of the Arctic but these people find a use for the entire walrus so they are very respectful in the manner that they use it.
The walrus is a very large animal and one that is believed to have evolved millions of years ago from a land creature.
Walruses feature front and back flippers that help them to swim as well as to move around on land. Due to their large size, a walrus is typically seen moving around at about 4 miles per hour. When necessary they can move at a speed of up to 20 miles per hour for short periods of time.
Walrus Research
There is still plenty that we don’t know about the walrus. Even though they have been researched for a very long time, too much of what they do isn’t well observed by humans. This is due to the isolated regions in which they live. Many things have been learned by observing the walruses that are in captivity. Yet we have to remember that they may not be the same as what would occur in the wild.
Humans and Walruses
- Humans and Walruses
- Walruses in Captivity
- Walruses in Popular Culture
- Walruses and Global Warming
- Walrus Hunting
The feeding habits of the walrus are very interesting. They consume foods from the bottom of the water including mollusks such as clams. They have also been known to feed on seals in the area when they need to. Due to the large size of these animals they have to consume large amounts of food each day. Generally that will be about 6% of their overall body weight.
Walrus Social Structure
The females are very protective of their young. They take care of them for about two years before they go out on their own. They bonding process between them is amazing. All of the walruses though seem to have a high level of communication. They also have a desire for physical contact with each other. It is for this reason that they have a very detailed social structure.
google_protectAndRun("ads_core.google_render_ad", google_handleError, google_render_ad); They form very large herds that have a hierarchy that is set up overall as well as for sub groups. Due to the many changes that occur in the life of a walrus they can move from one herd to the next. For example males are separate from females and those with offspring to care for are separate herds for that period of time as well.
Walrus Endangered
In the past the walrus has been in jeopardy of extinction due to low numbers. However, the early conservation efforts such as a preventing the sells of ivory have helped them to make a come back. They aren’t considered to be at risk at this time. However, they are still carefully watched to help ensure that the numbers don’t start to go down enough for interventions to be necessary.
Walruses. Image courtesy of NOAA.
Walruses and Global Warming
We also have to consider the fact that global warming is a huge problem for the walrus. They depend on those layers of ice to offer them a place to rest. It is also on the ice where the young are born. Since the people that live in the area of the walrus tend to be protective of them and to depend on them for meat, they don’t often engage in behaviors that will harm them such as releasing harmful chemicals into the water where they live.
Facts about Walruses google_protectAndRun("ads_core.google_render_ad", google_handleError, google_render_ad); How much do you really know about the walrus? Chances are there is plenty about them that you haven’t heard about before. As you read these walrus facts you can be confident that your knowledge about them is going to continue to expand. The name of the walrus means tooth walking sea horse.
The tusks of a full grown walrus can weight over 3 pounds each. Each one features from 400 to 700 whiskers. From a distance the walrus appears to be without fur. However, the entire body is covered with a very thin layer of it. The blubber, which is the layers of fat, on a walrus can be more than 5 inches thick.
A walrus can remain under water for up to 30 minutes before coming up for air. During migration they can travel up to 1,800 miles. The females tend to migrate further than the males. They can stand very cold water that is as low as -31 degrees Fahrenheit. When a calf is very young it will ride on the back of its mother in the water. However, it does know how to swim on its own. This method of movement is for protection and for bonding.
One of the leading causes of death for the walrus is due to various types of parasites in the water. They are able to cause problems for the skin as well as internal infections that shut down the normal functions of these animals. Males often kill each other during their fight for the right to mate or in an effort to move up the social status ladder. Females often keep their young underneath them to prevent them from being crushed by other adults in the area.
The skin of a walrus is very thick. This offers it protection from the extremely cold water as well as from many of the different predators out there. Many people are amused by the fact that the walrus can change colors. It has to do with their skin and their body temperatures. This is all due to the fact that their blood vessels change in size when it is cold versus when it is warmer. For example when it basks in the sun the skin turns red due to the amount of blood that rushes to the skin.
The walrus spends the cold winter months over the Bering Sea. It is common for them to pass through the Bering Strait during their migration patterns. One of the most amazing things about the walrus is that they are able to sleep while they are swimming! This is possible due to the air sacs that are located in the throat region.
There is only one species of walrus which is quite interesting. Most animals out there have many species so this is a fact that helps to identify them as unique in the eyes of researchers as well. Many people don’t realize that the walrus molts. This occurs in June or July as they no longer need their heavy winter coat.
When a walrus needs to break ice, it will do so by slamming its head against it. Then it will use the tusks to make the hole in the ice as large as it needs to. This process allows them to have breathing holes so they can stay under water for longer periods of time. They have to come up for air, but not all the way to the surface. For a very long time it was unknown how they were able to stay under water for so long. Now it is known that they are getting air but just from another source.
8/2/10 Polar Bear
The polar bear (Ursus maritimus) is a bear native largely within the Arctic circle encompassing the Arctic Ocean, its surrounding seas and surrounding land masses. It is the world's largest land carnivore and also the largest bear, together with the omnivorous Kodiak bear, which is approximately the same size.[3] An adult male weighs around 350–680 kg (770–1,500 lb),[4] while an adult female is about half that size. Although it is closely related to the brown bear, it has evolved to occupy a narrow ecological niche, with many body characteristics adapted for cold temperatures, for moving across snow, ice, and open water, and for hunting the seals which make up most of its diet.[5] Although most polar bears are born on land, they spend most of their time at sea (hence their scientific name meaning "maritime bear") and can hunt consistently only from sea ice, so spend much of the year on the frozen sea.
The polar bear is classified as a vulnerable species, with 8 of the 19 polar bear subpopulations in decline.[6] For decades, unrestricted hunting[clarification needed] raised international concern for the future of the species; populations have rebounded after controls and quotas began to take effect.[citation needed] For thousands of years, the polar bear has been a key figure in the material, spiritual, and cultural life of Arctic indigenous peoples, and the hunting of polar bears remains important in their cultures.
The IUCN now lists global warming as the most significant threat to the polar bear, primarily because the melting of its sea ice habitat reduces its ability to find sufficient food. The IUCN states, "If climatic trends continue polar bears may become extirpated from most of their range within 100 years."[7] The polar bear was listed as a threatened species under the Endangered Species Act by the United States Department of the Interior in 2008.
Naming and etymology Constantine John Phipps was the first to describe the polar bear as a distinct species.[7] He chose the scientific name Ursus maritimus, the Latin for 'maritime bear',[8] due to the animal's native habitat. The Inuit refer to the animal as nanook,[9] (transliterated as nanuuq in the Inupiaq language,[10]. The Yupik also refer to the bear by nanuuk in Siberian Yupik.[citation needed]) The bear is umka in the Chukchi language. In Russian, it is usually called бе́лый медве́дь (bélyj medvédj, the white bear), though an older word still in use is ошку́й (Oshkúj, which comes from the Komi oski, "bear").[11] In French, the polar bear is referred to as ours blanc ("white bear") or ours polaire ("polar bear").[12] In the Norwegian-administered Svalbard archipelago, the polar bear is referred to as Isbjørn ("ice bear").
The polar bear was previously considered to be in its own genus, Thalarctos.[13] However, evidence of hybrids between polar bears and brown bears, and of the recent evolutionary divergence of the two species, does not support the establishment of this separate genus, and the accepted scientific name is now therefore Ursus maritimus, as Phipps originally proposed.[14]
Taxonomy and evolution Polar bears depend on sea ice as a platform for hunting seals. Large feet and short, sharp, stocky claws are adaptations to this environment. The bear family, Ursidae, is believed to have split off from other carnivorans about 38 million years ago. The Ursinae subfamily originated approximately 4.2 million years ago. According to both fossil and DNA evidence, the polar bear diverged from the brown bear, Ursus arctos, roughly 150,000 years ago.[15] The oldest known polar bear fossil is a 130,000 to 110,000-year-old jaw bone, found on Prince Charles Foreland in 2004.[15] Fossils show that between ten to twenty thousand years ago, the polar bear's molar teeth changed significantly from those of the brown bear. Polar bears are thought to have diverged from a population of brown bears that became isolated during a period of glaciation in the Pleistocene.[16]
More recent genetic studies have shown that some clades of brown bear are more closely related to polar bears than to other brown bears,[17] meaning that the polar bear is not a true species according to some species concepts.[18] In addition, polar bears can breed with brown bears to produce fertile grizzly–polar bear hybrids,[16][19] indicating that they have only recently diverged and are genetically similar.[20] However, because neither species can survive long in the other's ecological niche, and because they have different morphology, metabolism, social and feeding behaviors, and other phenotypic characteristics, the two bears are generally classified as separate species.[20]
When the polar bear was originally documented, two subspecies were identified: Ursus maritimus maritimus by Constantine J. Phipps in 1774, and Ursus maritimus marinus by Peter Simon Pallas in 1776.[21] This distinction has since been invalidated.
One fossil subspecies has been identified. Ursus maritimus tyrannus—descended from Ursus arctos—became extinct during the Pleistocene. U.m. tyrannus was significantly larger than the living subspecies.[16]
Polar bears investigate the submarine USS Honolulu 280 miles (450 km) from the North Pole. Population and distribution The polar bear is found in the Arctic Circle and adjacent land masses. Due to the absence of human development in its remote habitat, it retains more of its original range than any other extant carnivore.[22] While they are rare north of 88°, there is evidence that they range all the way across the Arctic, and as far south as James Bay in Canada. They can occasionally drift widely with the sea ice, and there have been anecdotal sightings as far south as Berlevåg on the Norwegian mainland and the Kuril Islands in the Sea of Okhotsk. It is difficult to estimate a global population of polar bears as much of the range has been poorly studied, however biologists use a working estimate of about 20,000-25,000 polar bears worldwide.[1][23]
There are 19 generally recognized discrete subpopulations.[23][24] The subpopulations display seasonal fidelity to particular areas, but DNA studies show that they are not reproductively isolated.[25] The thirteen North American subpopulations range from the Beaufort Sea south to Hudson Bay and east to Baffin Bay in western Greenland and account for about 70% of the global population. The Eurasian population is broken up into the eastern Greenland, Barents Sea, Kara Sea, Laptev Sea, and Chukchi Sea subpopulations, though there is considerable uncertainty about the structure of these populations due to limited mark and recapture data.
Polar bears play-fighting The range includes the territory of five nations: Denmark (Greenland), Norway (Svalbard), Russia, the United States (Alaska) and Canada. These five nations are the signatories of the 1973 International Agreement for the Conservation of Polar Bears, which mandates cooperation on research and conservations efforts throughout the polar bear's range.
Modern methods of tracking polar bear populations have been implemented only since the mid-1980s, and are expensive to perform consistently over a large area.[26] The most accurate counts require flying a helicopter in the Arctic climate to find polar bears, shooting a tranquilizer dart at the bear to sedate it, and then tagging the bear.[26] In Nunavut, some Inuit have reported increases in bear sightings around human settlements in recent years, leading to a belief that populations are increasing. Scientists have responded by noting that hungry bears may be congregating around human settlements, leading to the illusion that populations are higher than they actually are.[26] The Polar Bear Specialist Group of the IUCN takes the position that "estimates of subpopulation size or sustainable harvest levels should not be made solely on the basis of traditional ecological knowledge without supporting scientific studies."[27]
Of the 19 recognized polar bear subpopulations, 8 are declining, 3 are stable, 1 is increasing, and 7 have insufficient data.[6][23]
Habitat A cub nursing The polar bear is often regarded as a marine mammal because it spends many months of the year at sea.[28] Its preferred habitat is the annual sea ice covering the waters over the continental shelf and the Arctic inter-island archipelagos. These areas, known as the "Arctic ring of life", have high biological productivity in comparison to the deep waters of the high Arctic.[22][29] The polar bear tends to frequent areas where sea ice meets water, such as polynyas and leads (temporary stretches of open water in Arctic ice), to hunt the seals that make up most of its diet.[30] Polar bears are therefore found primarily along the perimeter of the polar ice pack, rather than in the Polar Basin close to the North Pole where the density of seals is low.[31]
A polar bear. Annual ice contains areas of water that appear and disappear throughout the year as the weather changes. Seals migrate in response to these changes, and polar bears must follow their prey.[29] In Hudson Bay, James Bay, and some other areas, the ice melts completely each summer (an event often referred to as "ice-floe breakup"), forcing polar bears to go onto land and wait through the months until the next freeze-up.[29] In the Chukchi and Beaufort seas, polar bears retreat each summer to the ice further north that remains frozen year-round.
Biology and behavior Physical characteristics Polar bear skeleton The polar bear is the largest terrestrial carnivore, being more than twice as big as the Siberian Tiger.[32] It shares the title of largest land predator (and largest bear species) with the Kodiak bear.[33] Adult males weigh 350–680 kg (770-1500 lbs) and measure 2.4–3 m (7.9–9.8 ft) in length.[34] Adult females are roughly half the size of males and normally weigh 150–249 kg (330–550 lb), measuring 1.8–2.4 metres (5.9–7.9 ft) in length. When pregnant, however, they can weigh as much as 499 kg (1,100 lb).[34] The polar bear is among the most sexually dimorphic of mammals, surpassed only by the pinnipeds.[35] The largest polar bear on record, reportedly weighing 1,002 kg (2,210 lb), was a male shot at Kotzebue Sound in northwestern Alaska in 1960.[36]
Polar bears have evolved unique features for Arctic life, including furred feet that have good traction on ice. Compared with its closest relative, the brown bear, the polar bear has a more elongated body build and a longer skull and nose.[20] As predicted by Allen's rule for a northerly animal, the legs are stocky and the ears and tail are small.[20] However, the feet are very large to distribute load when walking on snow or thin ice and to provide propulsion when swimming; they may measure 30 cm (12 in) across in an adult.[37] The pads of the paws are covered with small, soft papillae (dermal bumps) which provide traction on the ice.[20] The polar bear's claws are short and stocky compared to those of the brown bear, perhaps to serve the former's need to grip heavy prey and ice.[20] The claws are deeply scooped on the underside to assist in digging in the ice of the natural habitat. Despite a recurring Internet meme that all polar bears are left-handed,[38][39] there is no scientific evidence to support this claim.[40] Unlike the brown bear, Polar Bears in captivity are rarely overweight or particularly large, possibly as a reaction to the warm temperatures of most zoos.
The 42 teeth of a polar bear reflect its highly carnivorous diet.[20] The cheek teeth are smaller and more jagged than in the brown bear, and the canines are larger and sharper.[20] The dental formula is:[20]
Dentition 3.1.4.2 3.1.4.3
Polar bears are superbly insulated by up to 10 cm (3.9 in) of blubber,[37] their hide and their fur; they overheat at temperatures above 10 °C (50 °F), and are nearly invisible under infrared photography.[41] Polar bear fur consists of a layer of dense underfur and an outer layer of guard hairs, which appear white to tan but are actually transparent.[37] The guard hair is 5–15 cm (2.0–5.9 in) over most of the body.[42] Polar bears gradually moult from May to August,[43] but, unlike other Arctic mammals, they do not shed their coat for a darker shade to camouflage themselves in the summer conditions. The hollow guard hairs of a polar bear coat were once thought to act as fiber-optic tubes to conduct light to its black skin, where it could be absorbed; however, this theory was disproved by recent studies.[44]
Polar bear diving in a zoo A polar bear in a synthetic arctic zoo environment. The white coat usually yellows with age. When kept in captivity in warm, humid conditions, the fur may turn a pale shade of green due to algae growing inside the guard hairs.[45] Males have significantly longer hairs on their forelegs, that increase in length until the bear reaches 14 years of age. The male's ornamental foreleg hair is thought to attract females, serving a similar function to the lion's mane.[46]
The polar bear has an extremely well-developed sense of smell, being able to detect seals nearly 1 mi (1.6 km) away and buried under 3 ft (0.91 m) of snow.[47] Its hearing is about as acute as that of a human, and its vision is also good at long distances.[47]
The polar bear is an excellent swimmer and individuals have been seen in open Arctic waters as far as 200 mi (320 km) from land. With its body fat providing buoyancy, it swims in a dog-paddle fashion using its large forepaws for propulsion.[48] Polar bears can swim 6 miles/hour. When walking, the polar bear tends to have a lumbering gait and maintains an average speed of around 5.5 km/h (3.5 m.p.h.).[48]
Hunting and diet The long muzzle and neck of the polar bear help it to search in deep holes for seals, while powerful hindquarters enable it to drag massive prey.[49] The polar bear is the most carnivorous member of the bear family, and most of its diet consists of ringed and bearded seals.[50] The Arctic is home to millions of seals, which become prey when they surface in holes in the ice in order to breathe, or when they haul out on the ice to rest.[49] Polar bears hunt primarily at the interface between ice, water, and air; they only rarely catch seals on land or in open water.[51]
The polar bear's most common hunting method is called still-hunting:[52] The bear uses its excellent sense of smell to locate a seal breathing hole, and crouches nearby in silence for a seal to appear.[49] When the seal exhales, the bear smells its breath, reaches into the hole with a forepaw, and drags it out onto the ice.[49] The polar bear kills the seal by biting its head to crush its skull.[49] The polar bear also hunts by stalking seals resting on the ice: Upon spotting a seal, it walks to within 100 yd (91 m), and then crouches. If the seal does not notice, the bear creeps to within 30 to 40 feet (9.1 to 12 m) of the seal and then suddenly rushes forth to attack.[49] A third hunting method is to raid the birth lairs that female seals create in the snow.[52]
Polar bear at a whale carcass A widespread legend tells that polar bears cover their black noses with their paws when hunting. This behavior, if it happens, is rare — although the story exists in native oral history and in accounts by early Arctic explorers, there is no record of an eyewitness account of the behavior in recent decades.[48]
Mature bears tend to eat only the calorie-rich skin and blubber of the seal, whereas younger bears consume the protein-rich red meat.[49] Studies have also photographed polar bears scaling near-vertical cliffs, to eat birds' chicks and eggs [53]. For subadult bears which are independent of their mother but have not yet gained enough experience and body size to successfully hunt seals, scavenging the carcasses from other bears' kills is an important source of nutrition. Subadults may also be forced to accept a half-eaten carcass if they kill a seal but cannot defend it from larger polar bears. After feeding, polar bears wash themselves with water or snow.[48]
The polar bear is an enormously powerful predator. It can kill an adult walrus, although it rarely attempts to as a walrus can be more than twice the bear's weight.[54] Polar bears also have preyed on beluga whales, by swiping at them at breathing holes. The whales are of similar size to the walrus and nearly as difficult for the bear to subdue. Most terrestrial animals in the Arctic can outrun the polar bear on land as polar bears overheat quickly, and most marine animals the bear encounters can outswim it. In some areas, the polar bear's diet is supplemented by walrus calves and by the carcasses of dead adult walruses or whales, whose blubber is readily devoured even when rotten.[55]
With the exception of pregnant females, polar bears are active year-round,[56] although they have a vestigial hibernation induction trigger in their blood. Unlike brown and black bears, polar bears are capable of fasting for up to several months during late summer and early fall, when they cannot hunt for seals because the sea is unfrozen.[56] When sea ice is unavailable during summer and early autumn, some populations live off fat reserves for months at a time.[41] Polar bears have also been observed to eat a wide variety of other wild foods, including muskox, reindeer, birds, eggs, rodents, shellfish, crabs, and other polar bears. They may also eat plants, including berries, roots, and kelp, however none of these are a significant part of their diet.[54] The polar bear's biology is specialized to require large amounts of fat from marine mammals, and it cannot derive sufficient caloric intake from terrestrial food.[57][58]
Being both curious animals and scavengers,[54][59] polar bears investigate and consume garbage where they come into contact with humans.[54] Polar bears may attempt to consume almost anything they can find, including hazardous substances such as styrofoam, plastic, car batteries, ethylene glycol, hydraulic fluid, and motor oil.[54][59] The dump in Churchill, Manitoba was closed in 2006 to protect bears, and waste is now recycled or transported to Thompson, Manitoba.[60][61]
Polar bear males frequently play-fight. During the mating season, actual fighting is intense and often leaves scars or broken teeth. Behavior Unlike grizzly bears, polar bears are not territorial. Although stereotyped as being voraciously aggressive, they are normally cautious in confrontations, and often choose to escape rather than fight.[62] Fat polar bears rarely attack humans unless severely provoked, whereas hungry polar bears are extremely unpredictable and are known to kill and sometimes eat humans.[55] Polar bears are stealth hunters, and the victim is often unaware of the bear's presence until the attack is underway.[63] Whereas brown bears often maul a person and then leave, polar bear attacks are more likely to be predatory and are almost always fatal.[63] However, due to the very small human population around the Arctic, such attacks are rare.
In general, adult polar bears live solitary lives. Yet, they have often been seen playing together for hours at a time and even sleeping in an embrace,[55] and polar bear zoologist Nikita Ovsianikov has described adult males as having "well-developed friendships."[62] Cubs are especially playful as well. Among young males in particular, play-fighting may be a means of practicing for serious competition during mating seasons later in life.[64] Polar bears have a wide range of vocalisations, including bellows, roars, growls, chuffs and purrs.[65]
In 1992, a photographer near Churchill took a now widely circulated set of photographs of a polar bear playing with a Canadian Eskimo Dog a tenth of its size.[66][67] The pair wrestled harmlessly together each afternoon for ten days in a row for no apparent reason, although the bear may have been trying to demonstrate its friendliness in the hope of sharing the kennel's food.[66] This kind of social interaction is uncommon; it is far more typical for polar bears to behave aggressively towards dogs.[66]
Reproduction and lifecycle A polar bear swimming Courtship and mating take place on the sea ice in April and May, when polar bears congregate in the best seal hunting areas.[68] A male may follow the tracks of a breeding female for 100 km (62 mi) or more, and after finding her engage in intense fighting with other males over mating rights, fights which often result in scars and broken teeth.[68] Polar bears have a generally polygynous mating system; recent genetic testing of mothers and cubs, however, has uncovered cases of litters in which cubs have different fathers.[69] Partners stay together and mate repeatedly for an entire week; the mating ritual induces ovulation in the female.[70]
After mating, the fertilized egg remains in a suspended state until August or September. During these four months, the pregnant female eats prodigious amounts of food, gaining at least 200 kg (440 lb) and often more than doubling her body weight.[68]
Maternity denning and early life Cubs are born helpless, and typically nurse for two and a half years. When the ice floes break up in the fall, ending the possibility of hunting, each pregnant female digs a maternity den consisting of a narrow entrance tunnel leading to one to three chambers.[68] Most maternity dens are in snowdrifts, but may also be made underground in permafrost if it is not sufficiently cold yet for snow.[68] In most subpopulations, maternity dens are situated on land a few kilometers from the coast, and the individuals in a subpopulation tend to reuse the same denning areas each year.[22] The polar bears that do not den on land make their dens on the sea ice. In the den, she enters a dormant state similar to hibernation. This hibernation-like state does not consist of continuous sleeping; however, the bear's heart rate slows from 46 to 27 beats per minute.[71] Her body temperature does not decrease during this period as it would for a typical mammal in hibernation.[41][72]
Between November and February, cubs are born blind, covered with a light down fur, and weighing less than 0.9 kg (2.0 lb).[70] On average, each litter has two cubs.[68] The family remains in the den until mid-February to mid-April, with the mother maintaining her fast while nursing her cubs on a fat-rich milk.[68] By the time the mother breaks open the entrance to the den, her cubs weigh about 10 to 15 kilograms (22 to 33 lb).[68] For about 12 to 15 days, the family spends time outside the den while remaining in its vicinity, the mother grazing on vegetation while the cubs become used to walking and playing.[68] Then they begin the long walk from the denning area to the sea ice, where the mother can once again catch seals.[68] Depending on the timing of ice-floe breakup in the fall, she may have fasted for up to eight months.[68]
Cubs may fall prey to wolves or to starvation. Female polar bears are noted for both their affection towards their offspring, and their valiance in protecting them. One case of adoption of a wild cub has been confirmed by genetic testing.[69] Adult male bears occasionally kill and eat polar bear cubs,[73] for reasons that are unclear.[74] In Alaska, 42% of cubs now reach 12 months of age, down from 65% 15 years ago.[75] In most areas, cubs are weaned at two and a half years of age,[68] when the mother chases them away or abandons them. The western coast of Hudson Bay is unusual in that its female polar bears sometimes wean their cubs at only one and a half years.[68] This was the case for 40% of cubs there in the early 1980s; however by the 1990s, fewer than 20% of cubs were weaned this young.[76] After the mother leaves, sibling cubs sometimes travel and share food together for weeks or months.[55]
A female emerging from her maternity den Later life Females begin to breed at the age of four years in most areas, and five years in the Beaufort Sea area.[68] Males usually reach sexual maturity at six years, however as competition for females is fierce, many do not breed until the age of eight or ten.[68] A study in Hudson Bay indicated that both the reproductive success and the maternal weight of females peaked in their mid-teens.[77]
Polar bears appear to be less affected by infectious diseases and parasites than most terrestrial mammals.[74] Polar bears are especially susceptible to Trichinella, a parasitic roundworm they contract through cannibalism,[78] although infections are usually not fatal.[74] Only one case of a polar bear with rabies has been documented, even though polar bears frequently interact with Arctic foxes, which often carry rabies.[74] Bacterial Leptospirosis and Morbillivirus have been recorded. Polar bears sometimes have problems with various skin diseases which may be caused by mites or other parasites.
Life expectancy Polar bears rarely live beyond 25 years.[79] The oldest wild bears on record died at the age of 32, whereas the oldest captive was a female who died in 1991 at the age of 43.[80] The oldest living polar bear is Debby of the Assiniboine Park Zoo, who was probably born in December, 1966.[80] The causes of death in wild adult polar bears are poorly understood, as carcasses are rarely found in the species's frigid habitat.[74] In the wild, old polar bears eventually become too weak to catch food, and gradually starve to death. Polar bears injured in fights or accidents may either die from their injuries or become unable to hunt effectively, leading to starvation.[74]
Ecological role A female nursing a two-year-old cub The polar bear is the apex predator within its range. Several animal species, particularly Arctic Foxes and Glaucous Gulls, routinely scavenge polar bear kills.[48]
The relationship between ringed seals and polar bears is so close that the abundance of ringed seals in some areas appears to regulate the density of polar bears, while polar bear predation in turn, regulates density and reproductive success of ringed seals.[51] The evolutionary pressure of polar bear predation on seals probably accounts for some significant differences between Arctic and Antarctic seals. Compared to the Antarctic, where there is no major surface predator, Arctic seals use more breathing holes per individual, appear more restless when hauled out on the ice, and rarely defecate on the ice.[48] The baby fur of most Arctic seal species is white, presumably to provide camouflage from predators, whereas Antarctic seals all have dark fur at birth.[48]
Polar bears rarely enter conflict with other predators, though recent brown bear encroachments into polar bear territories have led to antagonistic encounters. Brown bears tend to dominate polar bears in disputes over carcasses,[81] and dead polar bear cubs have been found in brown bear dens.[82] Wolves are rarely encountered by polar bears, though there are two records of wolf packs killing polar bear cubs.[83] Polar bears are sometimes the host of arctic mites such as Alaskozetes antarcticus.[48]
The polar bear is classified as a vulnerable species, with 8 of the 19 polar bear subpopulations in decline.[6] For decades, unrestricted hunting[clarification needed] raised international concern for the future of the species; populations have rebounded after controls and quotas began to take effect.[citation needed] For thousands of years, the polar bear has been a key figure in the material, spiritual, and cultural life of Arctic indigenous peoples, and the hunting of polar bears remains important in their cultures.
The IUCN now lists global warming as the most significant threat to the polar bear, primarily because the melting of its sea ice habitat reduces its ability to find sufficient food. The IUCN states, "If climatic trends continue polar bears may become extirpated from most of their range within 100 years."[7] The polar bear was listed as a threatened species under the Endangered Species Act by the United States Department of the Interior in 2008.
Naming and etymology Constantine John Phipps was the first to describe the polar bear as a distinct species.[7] He chose the scientific name Ursus maritimus, the Latin for 'maritime bear',[8] due to the animal's native habitat. The Inuit refer to the animal as nanook,[9] (transliterated as nanuuq in the Inupiaq language,[10]. The Yupik also refer to the bear by nanuuk in Siberian Yupik.[citation needed]) The bear is umka in the Chukchi language. In Russian, it is usually called бе́лый медве́дь (bélyj medvédj, the white bear), though an older word still in use is ошку́й (Oshkúj, which comes from the Komi oski, "bear").[11] In French, the polar bear is referred to as ours blanc ("white bear") or ours polaire ("polar bear").[12] In the Norwegian-administered Svalbard archipelago, the polar bear is referred to as Isbjørn ("ice bear").
The polar bear was previously considered to be in its own genus, Thalarctos.[13] However, evidence of hybrids between polar bears and brown bears, and of the recent evolutionary divergence of the two species, does not support the establishment of this separate genus, and the accepted scientific name is now therefore Ursus maritimus, as Phipps originally proposed.[14]
Taxonomy and evolution Polar bears depend on sea ice as a platform for hunting seals. Large feet and short, sharp, stocky claws are adaptations to this environment. The bear family, Ursidae, is believed to have split off from other carnivorans about 38 million years ago. The Ursinae subfamily originated approximately 4.2 million years ago. According to both fossil and DNA evidence, the polar bear diverged from the brown bear, Ursus arctos, roughly 150,000 years ago.[15] The oldest known polar bear fossil is a 130,000 to 110,000-year-old jaw bone, found on Prince Charles Foreland in 2004.[15] Fossils show that between ten to twenty thousand years ago, the polar bear's molar teeth changed significantly from those of the brown bear. Polar bears are thought to have diverged from a population of brown bears that became isolated during a period of glaciation in the Pleistocene.[16]
More recent genetic studies have shown that some clades of brown bear are more closely related to polar bears than to other brown bears,[17] meaning that the polar bear is not a true species according to some species concepts.[18] In addition, polar bears can breed with brown bears to produce fertile grizzly–polar bear hybrids,[16][19] indicating that they have only recently diverged and are genetically similar.[20] However, because neither species can survive long in the other's ecological niche, and because they have different morphology, metabolism, social and feeding behaviors, and other phenotypic characteristics, the two bears are generally classified as separate species.[20]
When the polar bear was originally documented, two subspecies were identified: Ursus maritimus maritimus by Constantine J. Phipps in 1774, and Ursus maritimus marinus by Peter Simon Pallas in 1776.[21] This distinction has since been invalidated.
One fossil subspecies has been identified. Ursus maritimus tyrannus—descended from Ursus arctos—became extinct during the Pleistocene. U.m. tyrannus was significantly larger than the living subspecies.[16]
Polar bears investigate the submarine USS Honolulu 280 miles (450 km) from the North Pole. Population and distribution The polar bear is found in the Arctic Circle and adjacent land masses. Due to the absence of human development in its remote habitat, it retains more of its original range than any other extant carnivore.[22] While they are rare north of 88°, there is evidence that they range all the way across the Arctic, and as far south as James Bay in Canada. They can occasionally drift widely with the sea ice, and there have been anecdotal sightings as far south as Berlevåg on the Norwegian mainland and the Kuril Islands in the Sea of Okhotsk. It is difficult to estimate a global population of polar bears as much of the range has been poorly studied, however biologists use a working estimate of about 20,000-25,000 polar bears worldwide.[1][23]
There are 19 generally recognized discrete subpopulations.[23][24] The subpopulations display seasonal fidelity to particular areas, but DNA studies show that they are not reproductively isolated.[25] The thirteen North American subpopulations range from the Beaufort Sea south to Hudson Bay and east to Baffin Bay in western Greenland and account for about 70% of the global population. The Eurasian population is broken up into the eastern Greenland, Barents Sea, Kara Sea, Laptev Sea, and Chukchi Sea subpopulations, though there is considerable uncertainty about the structure of these populations due to limited mark and recapture data.
Polar bears play-fighting The range includes the territory of five nations: Denmark (Greenland), Norway (Svalbard), Russia, the United States (Alaska) and Canada. These five nations are the signatories of the 1973 International Agreement for the Conservation of Polar Bears, which mandates cooperation on research and conservations efforts throughout the polar bear's range.
Modern methods of tracking polar bear populations have been implemented only since the mid-1980s, and are expensive to perform consistently over a large area.[26] The most accurate counts require flying a helicopter in the Arctic climate to find polar bears, shooting a tranquilizer dart at the bear to sedate it, and then tagging the bear.[26] In Nunavut, some Inuit have reported increases in bear sightings around human settlements in recent years, leading to a belief that populations are increasing. Scientists have responded by noting that hungry bears may be congregating around human settlements, leading to the illusion that populations are higher than they actually are.[26] The Polar Bear Specialist Group of the IUCN takes the position that "estimates of subpopulation size or sustainable harvest levels should not be made solely on the basis of traditional ecological knowledge without supporting scientific studies."[27]
Of the 19 recognized polar bear subpopulations, 8 are declining, 3 are stable, 1 is increasing, and 7 have insufficient data.[6][23]
Habitat A cub nursing The polar bear is often regarded as a marine mammal because it spends many months of the year at sea.[28] Its preferred habitat is the annual sea ice covering the waters over the continental shelf and the Arctic inter-island archipelagos. These areas, known as the "Arctic ring of life", have high biological productivity in comparison to the deep waters of the high Arctic.[22][29] The polar bear tends to frequent areas where sea ice meets water, such as polynyas and leads (temporary stretches of open water in Arctic ice), to hunt the seals that make up most of its diet.[30] Polar bears are therefore found primarily along the perimeter of the polar ice pack, rather than in the Polar Basin close to the North Pole where the density of seals is low.[31]
A polar bear. Annual ice contains areas of water that appear and disappear throughout the year as the weather changes. Seals migrate in response to these changes, and polar bears must follow their prey.[29] In Hudson Bay, James Bay, and some other areas, the ice melts completely each summer (an event often referred to as "ice-floe breakup"), forcing polar bears to go onto land and wait through the months until the next freeze-up.[29] In the Chukchi and Beaufort seas, polar bears retreat each summer to the ice further north that remains frozen year-round.
Biology and behavior Physical characteristics Polar bear skeleton The polar bear is the largest terrestrial carnivore, being more than twice as big as the Siberian Tiger.[32] It shares the title of largest land predator (and largest bear species) with the Kodiak bear.[33] Adult males weigh 350–680 kg (770-1500 lbs) and measure 2.4–3 m (7.9–9.8 ft) in length.[34] Adult females are roughly half the size of males and normally weigh 150–249 kg (330–550 lb), measuring 1.8–2.4 metres (5.9–7.9 ft) in length. When pregnant, however, they can weigh as much as 499 kg (1,100 lb).[34] The polar bear is among the most sexually dimorphic of mammals, surpassed only by the pinnipeds.[35] The largest polar bear on record, reportedly weighing 1,002 kg (2,210 lb), was a male shot at Kotzebue Sound in northwestern Alaska in 1960.[36]
Polar bears have evolved unique features for Arctic life, including furred feet that have good traction on ice. Compared with its closest relative, the brown bear, the polar bear has a more elongated body build and a longer skull and nose.[20] As predicted by Allen's rule for a northerly animal, the legs are stocky and the ears and tail are small.[20] However, the feet are very large to distribute load when walking on snow or thin ice and to provide propulsion when swimming; they may measure 30 cm (12 in) across in an adult.[37] The pads of the paws are covered with small, soft papillae (dermal bumps) which provide traction on the ice.[20] The polar bear's claws are short and stocky compared to those of the brown bear, perhaps to serve the former's need to grip heavy prey and ice.[20] The claws are deeply scooped on the underside to assist in digging in the ice of the natural habitat. Despite a recurring Internet meme that all polar bears are left-handed,[38][39] there is no scientific evidence to support this claim.[40] Unlike the brown bear, Polar Bears in captivity are rarely overweight or particularly large, possibly as a reaction to the warm temperatures of most zoos.
The 42 teeth of a polar bear reflect its highly carnivorous diet.[20] The cheek teeth are smaller and more jagged than in the brown bear, and the canines are larger and sharper.[20] The dental formula is:[20]
Dentition 3.1.4.2 3.1.4.3
Polar bears are superbly insulated by up to 10 cm (3.9 in) of blubber,[37] their hide and their fur; they overheat at temperatures above 10 °C (50 °F), and are nearly invisible under infrared photography.[41] Polar bear fur consists of a layer of dense underfur and an outer layer of guard hairs, which appear white to tan but are actually transparent.[37] The guard hair is 5–15 cm (2.0–5.9 in) over most of the body.[42] Polar bears gradually moult from May to August,[43] but, unlike other Arctic mammals, they do not shed their coat for a darker shade to camouflage themselves in the summer conditions. The hollow guard hairs of a polar bear coat were once thought to act as fiber-optic tubes to conduct light to its black skin, where it could be absorbed; however, this theory was disproved by recent studies.[44]
Polar bear diving in a zoo A polar bear in a synthetic arctic zoo environment. The white coat usually yellows with age. When kept in captivity in warm, humid conditions, the fur may turn a pale shade of green due to algae growing inside the guard hairs.[45] Males have significantly longer hairs on their forelegs, that increase in length until the bear reaches 14 years of age. The male's ornamental foreleg hair is thought to attract females, serving a similar function to the lion's mane.[46]
The polar bear has an extremely well-developed sense of smell, being able to detect seals nearly 1 mi (1.6 km) away and buried under 3 ft (0.91 m) of snow.[47] Its hearing is about as acute as that of a human, and its vision is also good at long distances.[47]
The polar bear is an excellent swimmer and individuals have been seen in open Arctic waters as far as 200 mi (320 km) from land. With its body fat providing buoyancy, it swims in a dog-paddle fashion using its large forepaws for propulsion.[48] Polar bears can swim 6 miles/hour. When walking, the polar bear tends to have a lumbering gait and maintains an average speed of around 5.5 km/h (3.5 m.p.h.).[48]
Hunting and diet The long muzzle and neck of the polar bear help it to search in deep holes for seals, while powerful hindquarters enable it to drag massive prey.[49] The polar bear is the most carnivorous member of the bear family, and most of its diet consists of ringed and bearded seals.[50] The Arctic is home to millions of seals, which become prey when they surface in holes in the ice in order to breathe, or when they haul out on the ice to rest.[49] Polar bears hunt primarily at the interface between ice, water, and air; they only rarely catch seals on land or in open water.[51]
The polar bear's most common hunting method is called still-hunting:[52] The bear uses its excellent sense of smell to locate a seal breathing hole, and crouches nearby in silence for a seal to appear.[49] When the seal exhales, the bear smells its breath, reaches into the hole with a forepaw, and drags it out onto the ice.[49] The polar bear kills the seal by biting its head to crush its skull.[49] The polar bear also hunts by stalking seals resting on the ice: Upon spotting a seal, it walks to within 100 yd (91 m), and then crouches. If the seal does not notice, the bear creeps to within 30 to 40 feet (9.1 to 12 m) of the seal and then suddenly rushes forth to attack.[49] A third hunting method is to raid the birth lairs that female seals create in the snow.[52]
Polar bear at a whale carcass A widespread legend tells that polar bears cover their black noses with their paws when hunting. This behavior, if it happens, is rare — although the story exists in native oral history and in accounts by early Arctic explorers, there is no record of an eyewitness account of the behavior in recent decades.[48]
Mature bears tend to eat only the calorie-rich skin and blubber of the seal, whereas younger bears consume the protein-rich red meat.[49] Studies have also photographed polar bears scaling near-vertical cliffs, to eat birds' chicks and eggs [53]. For subadult bears which are independent of their mother but have not yet gained enough experience and body size to successfully hunt seals, scavenging the carcasses from other bears' kills is an important source of nutrition. Subadults may also be forced to accept a half-eaten carcass if they kill a seal but cannot defend it from larger polar bears. After feeding, polar bears wash themselves with water or snow.[48]
The polar bear is an enormously powerful predator. It can kill an adult walrus, although it rarely attempts to as a walrus can be more than twice the bear's weight.[54] Polar bears also have preyed on beluga whales, by swiping at them at breathing holes. The whales are of similar size to the walrus and nearly as difficult for the bear to subdue. Most terrestrial animals in the Arctic can outrun the polar bear on land as polar bears overheat quickly, and most marine animals the bear encounters can outswim it. In some areas, the polar bear's diet is supplemented by walrus calves and by the carcasses of dead adult walruses or whales, whose blubber is readily devoured even when rotten.[55]
With the exception of pregnant females, polar bears are active year-round,[56] although they have a vestigial hibernation induction trigger in their blood. Unlike brown and black bears, polar bears are capable of fasting for up to several months during late summer and early fall, when they cannot hunt for seals because the sea is unfrozen.[56] When sea ice is unavailable during summer and early autumn, some populations live off fat reserves for months at a time.[41] Polar bears have also been observed to eat a wide variety of other wild foods, including muskox, reindeer, birds, eggs, rodents, shellfish, crabs, and other polar bears. They may also eat plants, including berries, roots, and kelp, however none of these are a significant part of their diet.[54] The polar bear's biology is specialized to require large amounts of fat from marine mammals, and it cannot derive sufficient caloric intake from terrestrial food.[57][58]
Being both curious animals and scavengers,[54][59] polar bears investigate and consume garbage where they come into contact with humans.[54] Polar bears may attempt to consume almost anything they can find, including hazardous substances such as styrofoam, plastic, car batteries, ethylene glycol, hydraulic fluid, and motor oil.[54][59] The dump in Churchill, Manitoba was closed in 2006 to protect bears, and waste is now recycled or transported to Thompson, Manitoba.[60][61]
Polar bear males frequently play-fight. During the mating season, actual fighting is intense and often leaves scars or broken teeth. Behavior Unlike grizzly bears, polar bears are not territorial. Although stereotyped as being voraciously aggressive, they are normally cautious in confrontations, and often choose to escape rather than fight.[62] Fat polar bears rarely attack humans unless severely provoked, whereas hungry polar bears are extremely unpredictable and are known to kill and sometimes eat humans.[55] Polar bears are stealth hunters, and the victim is often unaware of the bear's presence until the attack is underway.[63] Whereas brown bears often maul a person and then leave, polar bear attacks are more likely to be predatory and are almost always fatal.[63] However, due to the very small human population around the Arctic, such attacks are rare.
In general, adult polar bears live solitary lives. Yet, they have often been seen playing together for hours at a time and even sleeping in an embrace,[55] and polar bear zoologist Nikita Ovsianikov has described adult males as having "well-developed friendships."[62] Cubs are especially playful as well. Among young males in particular, play-fighting may be a means of practicing for serious competition during mating seasons later in life.[64] Polar bears have a wide range of vocalisations, including bellows, roars, growls, chuffs and purrs.[65]
In 1992, a photographer near Churchill took a now widely circulated set of photographs of a polar bear playing with a Canadian Eskimo Dog a tenth of its size.[66][67] The pair wrestled harmlessly together each afternoon for ten days in a row for no apparent reason, although the bear may have been trying to demonstrate its friendliness in the hope of sharing the kennel's food.[66] This kind of social interaction is uncommon; it is far more typical for polar bears to behave aggressively towards dogs.[66]
Reproduction and lifecycle A polar bear swimming Courtship and mating take place on the sea ice in April and May, when polar bears congregate in the best seal hunting areas.[68] A male may follow the tracks of a breeding female for 100 km (62 mi) or more, and after finding her engage in intense fighting with other males over mating rights, fights which often result in scars and broken teeth.[68] Polar bears have a generally polygynous mating system; recent genetic testing of mothers and cubs, however, has uncovered cases of litters in which cubs have different fathers.[69] Partners stay together and mate repeatedly for an entire week; the mating ritual induces ovulation in the female.[70]
After mating, the fertilized egg remains in a suspended state until August or September. During these four months, the pregnant female eats prodigious amounts of food, gaining at least 200 kg (440 lb) and often more than doubling her body weight.[68]
Maternity denning and early life Cubs are born helpless, and typically nurse for two and a half years. When the ice floes break up in the fall, ending the possibility of hunting, each pregnant female digs a maternity den consisting of a narrow entrance tunnel leading to one to three chambers.[68] Most maternity dens are in snowdrifts, but may also be made underground in permafrost if it is not sufficiently cold yet for snow.[68] In most subpopulations, maternity dens are situated on land a few kilometers from the coast, and the individuals in a subpopulation tend to reuse the same denning areas each year.[22] The polar bears that do not den on land make their dens on the sea ice. In the den, she enters a dormant state similar to hibernation. This hibernation-like state does not consist of continuous sleeping; however, the bear's heart rate slows from 46 to 27 beats per minute.[71] Her body temperature does not decrease during this period as it would for a typical mammal in hibernation.[41][72]
Between November and February, cubs are born blind, covered with a light down fur, and weighing less than 0.9 kg (2.0 lb).[70] On average, each litter has two cubs.[68] The family remains in the den until mid-February to mid-April, with the mother maintaining her fast while nursing her cubs on a fat-rich milk.[68] By the time the mother breaks open the entrance to the den, her cubs weigh about 10 to 15 kilograms (22 to 33 lb).[68] For about 12 to 15 days, the family spends time outside the den while remaining in its vicinity, the mother grazing on vegetation while the cubs become used to walking and playing.[68] Then they begin the long walk from the denning area to the sea ice, where the mother can once again catch seals.[68] Depending on the timing of ice-floe breakup in the fall, she may have fasted for up to eight months.[68]
Cubs may fall prey to wolves or to starvation. Female polar bears are noted for both their affection towards their offspring, and their valiance in protecting them. One case of adoption of a wild cub has been confirmed by genetic testing.[69] Adult male bears occasionally kill and eat polar bear cubs,[73] for reasons that are unclear.[74] In Alaska, 42% of cubs now reach 12 months of age, down from 65% 15 years ago.[75] In most areas, cubs are weaned at two and a half years of age,[68] when the mother chases them away or abandons them. The western coast of Hudson Bay is unusual in that its female polar bears sometimes wean their cubs at only one and a half years.[68] This was the case for 40% of cubs there in the early 1980s; however by the 1990s, fewer than 20% of cubs were weaned this young.[76] After the mother leaves, sibling cubs sometimes travel and share food together for weeks or months.[55]
A female emerging from her maternity den Later life Females begin to breed at the age of four years in most areas, and five years in the Beaufort Sea area.[68] Males usually reach sexual maturity at six years, however as competition for females is fierce, many do not breed until the age of eight or ten.[68] A study in Hudson Bay indicated that both the reproductive success and the maternal weight of females peaked in their mid-teens.[77]
Polar bears appear to be less affected by infectious diseases and parasites than most terrestrial mammals.[74] Polar bears are especially susceptible to Trichinella, a parasitic roundworm they contract through cannibalism,[78] although infections are usually not fatal.[74] Only one case of a polar bear with rabies has been documented, even though polar bears frequently interact with Arctic foxes, which often carry rabies.[74] Bacterial Leptospirosis and Morbillivirus have been recorded. Polar bears sometimes have problems with various skin diseases which may be caused by mites or other parasites.
Life expectancy Polar bears rarely live beyond 25 years.[79] The oldest wild bears on record died at the age of 32, whereas the oldest captive was a female who died in 1991 at the age of 43.[80] The oldest living polar bear is Debby of the Assiniboine Park Zoo, who was probably born in December, 1966.[80] The causes of death in wild adult polar bears are poorly understood, as carcasses are rarely found in the species's frigid habitat.[74] In the wild, old polar bears eventually become too weak to catch food, and gradually starve to death. Polar bears injured in fights or accidents may either die from their injuries or become unable to hunt effectively, leading to starvation.[74]
Ecological role A female nursing a two-year-old cub The polar bear is the apex predator within its range. Several animal species, particularly Arctic Foxes and Glaucous Gulls, routinely scavenge polar bear kills.[48]
The relationship between ringed seals and polar bears is so close that the abundance of ringed seals in some areas appears to regulate the density of polar bears, while polar bear predation in turn, regulates density and reproductive success of ringed seals.[51] The evolutionary pressure of polar bear predation on seals probably accounts for some significant differences between Arctic and Antarctic seals. Compared to the Antarctic, where there is no major surface predator, Arctic seals use more breathing holes per individual, appear more restless when hauled out on the ice, and rarely defecate on the ice.[48] The baby fur of most Arctic seal species is white, presumably to provide camouflage from predators, whereas Antarctic seals all have dark fur at birth.[48]
Polar bears rarely enter conflict with other predators, though recent brown bear encroachments into polar bear territories have led to antagonistic encounters. Brown bears tend to dominate polar bears in disputes over carcasses,[81] and dead polar bear cubs have been found in brown bear dens.[82] Wolves are rarely encountered by polar bears, though there are two records of wolf packs killing polar bear cubs.[83] Polar bears are sometimes the host of arctic mites such as Alaskozetes antarcticus.[48]
7/5/10 Chameleons
Chameleons (family Chamaeleonidae) are a distinctive and highly specialized clade of lizards. They are distinguished by their parrot-like zygodactylous feet, their separately mobile and stereoscopic eyes, their very long, highly modified, and rapidly extrudable tongues, their swaying gait, the possession by many of a prehensile tail, crests or horns on their distinctively shaped heads, and the ability of some to change color. Uniquely adapted for climbing and visual hunting, the approximately 160 species of chameleon range from Africa, Madagascar, Spain and Portugal, across south Asia, to Sri Lanka, have been introduced to Hawaii, California and Florida, and are found in warm habitats that vary from rain forest to desert conditions.
Etymology The English word chameleon (also chamaeleon) derives from the Latin chamaeleo which is borrowed from the Ancient Greek χαμαιλέων (khamaileon), a compound of χαμαί (khamai) "on the earth, on the ground" + λέων (leon) "lion". The Greek word is a calque translating the Akkadian nēš qaqqari, "ground lion".[1]
Evolution The oldest known chameleon fossil is that of Chamaeleo caroliquarti, found in Europe and dated to about 26 mya. However the chameleons are probably far older than that, perhaps sharing a common ancestor with iguanids and agamids more than 100 mya (agamids being more closely related). Fossil evidence has also been found in Africa and Asia, and suggests that chameleons were once more widespread than they are today. They may have their origins in Madagascar, which today is home to nearly half of all the 150 or more known species in this family, and later dispersed to other areas.[2]
Description Cape Dwarf Chameleon, Tokai, South Africa Chameleons vary greatly in size and body structure, with maximum total length varying from 3.3 cm (1.3 in.) in Brookesia minima (one of the world's smallest reptiles) to 68.5 cm (27 in.) in the male Furcifer oustaleti.[3] Many have head or facial ornamentation, such as nasal protrusions, or horn-like projections in the case of Chamaeleo jacksonii, or large crests on top of their head, like Chamaeleo calyptratus. Many species are sexually dimorphic, and males are typically much more ornamented than the female chameleons.
Chameleon species have in common their foot structure, eyes, lack of ears, and tongues.
Oustalet's Chameleon, Ambalavao, Madagascar Chameleons are didactyl: on each foot the five toes are fused into a group of two and a group of three, giving the foot a tongs-like appearance. These specialized feet allow chameleons to grip tightly to narrow branches. Each toe is equipped with a sharp claw to gain traction on surfaces such as bark when climbing. The claws make it easy to see how many toes are fused into each part of the foot — two toes on the outside of each front foot and three on the inside.
Their eyes are the most distinctive among the reptiles. The upper and lower eyelids are joined, with only a pinhole large enough for the pupil to see through. They can rotate and focus separately to observe two different objects simultaneously. It in effect gives them a full 360-degree arc of vision around their body. When prey is located, both eyes can be focused in the same direction, giving sharp stereoscopic vision and depth perception. They have very good eyesight for reptiles, letting them see small insects from a long (5-10 cm) distance.
They lack a vomeronasal organ. Also, like snakes, they do not have an outer or a middle ear. This suggests that chameleons might be deaf, although it should be noted that snakes can sense vibration using a bone called the quadrate. Furthermore, some or maybe all chameleons, can communicate via vibrations that travel through solid substrates such as branches.
Chameleons have very long tongues (sometimes longer than their own body length) which they are capable of rapidly extending out of the mouth.
Tongue structure The tongue extends out faster than human eyes can follow, at around 26 body lengths per second. The tongue hits the prey in about 30 thousandths of a second.[4] The tongue of the chameleon is a complex arrangement of bone, muscle and sinew. At the base of the tongue there is a bone and this is shot forward giving the tongue the initial momentum it needs to reach the prey quickly. At the tip of the elastic tongue there is a muscular, club-like structure covered in thick mucus that forms a suction cup.[5] Once the tip sticks to a prey item, it is drawn quickly back into the mouth, where the chameleon's strong jaws crush it and it is consumed. Ultraviolet light is part of the visible spectrum for chameleons.[6] Chameleons exposed to ultraviolet light show increased social behavior and activity levels, are more inclined to bask and feed and are also more likely to reproduce as it has a positive effect on the pineal gland.
Distribution and habitat The tiny, usually brown-colored Brookesia chameleons are mainly terrestrial Chameleons are primarily found in the mainland of sub-Saharan Africa and on the island of Madagascar, although a few species are also found in northern Africa, southern Europe, the Middle East, southern India, Sri Lanka and several smaller islands in the western Indian Ocean. There are introduced, feral populations of veiled and Jackson's chameleons in Hawaii and isolated pockets of feral Jackson's chameleons have been reported in California and Florida.
Chameleons inhabit all kinds of tropical and mountain rain forests, savannas and sometimes deserts and steppes. The "typical" chameleons from the subfamily Chamaeleoninae are arboreal and usually found in trees or bushes, although a few (notably the Namaqua Chameleon) are partially or largely terrestrial. Most species from the subfamily Brookesiinae, which includes the genera Brookesia, Rieppeleon and Rhampholeon, live low in vegetation or on the ground among leaf litter.
Reproduction West Usambara Two-Horned Chameleon (Kinyongia multituberculata) in the Usambara mountains, Tanzania. Chameleons are mostly oviparous, some being ovoviviparous.
The oviparous species lay eggs after a 3–6 week gestation period. The female will climb down to the ground and begin digging a hole, anywhere from 10–30 cm (4–12 in.) deep depending on the species. The female turns herself around at the bottom of the hole and deposits her eggs. Once finished, the female buries lina[clarification needed] and leaves the nesting site. Clutch sizes vary greatly with species. Small Brookesia species may only lay 2–4 eggs, while large Veiled Chameleons (Chamaeleo calyptratus) have been known to lay clutches of 80–100 eggs. Clutch sizes can also vary greatly among the same species. Eggs generally hatch after 4–12 months, again depending on species. The eggs of Parson's Chameleon (Calumma parsonii), a species which is rare in captivity, are believed to take upwards of 24 months to hatch.
The ovoviviparous species, such as the Jackson's Chameleon (Chamaeleo jacksonii) have a 5–6 month gestation period. The newborn are in a transparent membrane and they are still sleeping, once they touch the ground or branch, they will wake up and attempt to crawl out of the membrane.[citation needed] The female can have 8–31 live young at once.
Feeding behaviour Chameleons generally eat locusts, mantis, crickets, grasshopper and other insects, but larger chameleons have been known to eat small birds and other lizards. A few species, such as Jackson's Chameleon (C. jacksonii) and the Veiled Chameleon (C. calyptratus) will consume small amounts of plant matter. Chameleons prefer running water to still water.[citation needed]
Chameleons require lots of vitamins and minerals[citation needed]. To ensure sufficient nutrients, zoo-keepers "gut-load" insects before feeding them to chameleons, by rearing them on a diet of potatoes, fish flakes (tropical), dry puppy food, dark leafy greens, etc. and dusting them with vitamin and mineral powders.[citation needed]
Change of color This Common Chameleon (Chamaeleo chamaeleon) turned black Some chameleon species are able to change their skin colors. Different chameleon species are able to change different colors which can include pink, blue, red, orange, green, black, brown, light blue, yellow and turquoise.[7][8]
Some varieties of chameleon - such as the Smith's dwarf chameleon - use their color-changing ability to blend in with their surroundings, as an effective form of camouflage.[9]
Color change is also used as an expression of the physiological condition of the lizard, and as a social indicator to other chameleons. Some research suggests that social signalling was the primary driving force behind the evolution of color change, and that camouflage evolved as a secondary concern.[10][11]
Chameleons have specialized cells, collectively called chromatophores, that lie in layers under their transparent outer skin. The cells in the upper layer, called xanthophores and erythrophores, contain yellow and red pigments respectively. Below these is another layer of cells called iridophores or guanophores, and they contain the colorless crystalline substance guanine. These are particularly strong reflectors of the blue part of incident light. If the upper layer of chromatophores appears mainly yellow, the reflected light becomes green (blue plus yellow). A layer of dark melanin contained in melanophores is situated even deeper under the reflective iridophores. The melanophores determine the 'lightness' of the reflected light. These specialized cells are full of pigment granules, which are located in their cytoplasm. Dispersion of the pigment granules in the cell grants the intensity of appropriate color. If the pigment is equally distributed in the cell, the whole cell has the intensive color, which depends on the type of chromatophore cell. If the pigment is located only in the centre of the cell, cell appears to be transparent. All these pigment cells can rapidly relocate their pigments, thereby influencing the color of the chameleon.
Etymology The English word chameleon (also chamaeleon) derives from the Latin chamaeleo which is borrowed from the Ancient Greek χαμαιλέων (khamaileon), a compound of χαμαί (khamai) "on the earth, on the ground" + λέων (leon) "lion". The Greek word is a calque translating the Akkadian nēš qaqqari, "ground lion".[1]
Evolution The oldest known chameleon fossil is that of Chamaeleo caroliquarti, found in Europe and dated to about 26 mya. However the chameleons are probably far older than that, perhaps sharing a common ancestor with iguanids and agamids more than 100 mya (agamids being more closely related). Fossil evidence has also been found in Africa and Asia, and suggests that chameleons were once more widespread than they are today. They may have their origins in Madagascar, which today is home to nearly half of all the 150 or more known species in this family, and later dispersed to other areas.[2]
Description Cape Dwarf Chameleon, Tokai, South Africa Chameleons vary greatly in size and body structure, with maximum total length varying from 3.3 cm (1.3 in.) in Brookesia minima (one of the world's smallest reptiles) to 68.5 cm (27 in.) in the male Furcifer oustaleti.[3] Many have head or facial ornamentation, such as nasal protrusions, or horn-like projections in the case of Chamaeleo jacksonii, or large crests on top of their head, like Chamaeleo calyptratus. Many species are sexually dimorphic, and males are typically much more ornamented than the female chameleons.
Chameleon species have in common their foot structure, eyes, lack of ears, and tongues.
Oustalet's Chameleon, Ambalavao, Madagascar Chameleons are didactyl: on each foot the five toes are fused into a group of two and a group of three, giving the foot a tongs-like appearance. These specialized feet allow chameleons to grip tightly to narrow branches. Each toe is equipped with a sharp claw to gain traction on surfaces such as bark when climbing. The claws make it easy to see how many toes are fused into each part of the foot — two toes on the outside of each front foot and three on the inside.
Their eyes are the most distinctive among the reptiles. The upper and lower eyelids are joined, with only a pinhole large enough for the pupil to see through. They can rotate and focus separately to observe two different objects simultaneously. It in effect gives them a full 360-degree arc of vision around their body. When prey is located, both eyes can be focused in the same direction, giving sharp stereoscopic vision and depth perception. They have very good eyesight for reptiles, letting them see small insects from a long (5-10 cm) distance.
They lack a vomeronasal organ. Also, like snakes, they do not have an outer or a middle ear. This suggests that chameleons might be deaf, although it should be noted that snakes can sense vibration using a bone called the quadrate. Furthermore, some or maybe all chameleons, can communicate via vibrations that travel through solid substrates such as branches.
Chameleons have very long tongues (sometimes longer than their own body length) which they are capable of rapidly extending out of the mouth.
Tongue structure The tongue extends out faster than human eyes can follow, at around 26 body lengths per second. The tongue hits the prey in about 30 thousandths of a second.[4] The tongue of the chameleon is a complex arrangement of bone, muscle and sinew. At the base of the tongue there is a bone and this is shot forward giving the tongue the initial momentum it needs to reach the prey quickly. At the tip of the elastic tongue there is a muscular, club-like structure covered in thick mucus that forms a suction cup.[5] Once the tip sticks to a prey item, it is drawn quickly back into the mouth, where the chameleon's strong jaws crush it and it is consumed. Ultraviolet light is part of the visible spectrum for chameleons.[6] Chameleons exposed to ultraviolet light show increased social behavior and activity levels, are more inclined to bask and feed and are also more likely to reproduce as it has a positive effect on the pineal gland.
Distribution and habitat The tiny, usually brown-colored Brookesia chameleons are mainly terrestrial Chameleons are primarily found in the mainland of sub-Saharan Africa and on the island of Madagascar, although a few species are also found in northern Africa, southern Europe, the Middle East, southern India, Sri Lanka and several smaller islands in the western Indian Ocean. There are introduced, feral populations of veiled and Jackson's chameleons in Hawaii and isolated pockets of feral Jackson's chameleons have been reported in California and Florida.
Chameleons inhabit all kinds of tropical and mountain rain forests, savannas and sometimes deserts and steppes. The "typical" chameleons from the subfamily Chamaeleoninae are arboreal and usually found in trees or bushes, although a few (notably the Namaqua Chameleon) are partially or largely terrestrial. Most species from the subfamily Brookesiinae, which includes the genera Brookesia, Rieppeleon and Rhampholeon, live low in vegetation or on the ground among leaf litter.
Reproduction West Usambara Two-Horned Chameleon (Kinyongia multituberculata) in the Usambara mountains, Tanzania. Chameleons are mostly oviparous, some being ovoviviparous.
The oviparous species lay eggs after a 3–6 week gestation period. The female will climb down to the ground and begin digging a hole, anywhere from 10–30 cm (4–12 in.) deep depending on the species. The female turns herself around at the bottom of the hole and deposits her eggs. Once finished, the female buries lina[clarification needed] and leaves the nesting site. Clutch sizes vary greatly with species. Small Brookesia species may only lay 2–4 eggs, while large Veiled Chameleons (Chamaeleo calyptratus) have been known to lay clutches of 80–100 eggs. Clutch sizes can also vary greatly among the same species. Eggs generally hatch after 4–12 months, again depending on species. The eggs of Parson's Chameleon (Calumma parsonii), a species which is rare in captivity, are believed to take upwards of 24 months to hatch.
The ovoviviparous species, such as the Jackson's Chameleon (Chamaeleo jacksonii) have a 5–6 month gestation period. The newborn are in a transparent membrane and they are still sleeping, once they touch the ground or branch, they will wake up and attempt to crawl out of the membrane.[citation needed] The female can have 8–31 live young at once.
Feeding behaviour Chameleons generally eat locusts, mantis, crickets, grasshopper and other insects, but larger chameleons have been known to eat small birds and other lizards. A few species, such as Jackson's Chameleon (C. jacksonii) and the Veiled Chameleon (C. calyptratus) will consume small amounts of plant matter. Chameleons prefer running water to still water.[citation needed]
Chameleons require lots of vitamins and minerals[citation needed]. To ensure sufficient nutrients, zoo-keepers "gut-load" insects before feeding them to chameleons, by rearing them on a diet of potatoes, fish flakes (tropical), dry puppy food, dark leafy greens, etc. and dusting them with vitamin and mineral powders.[citation needed]
Change of color This Common Chameleon (Chamaeleo chamaeleon) turned black Some chameleon species are able to change their skin colors. Different chameleon species are able to change different colors which can include pink, blue, red, orange, green, black, brown, light blue, yellow and turquoise.[7][8]
Some varieties of chameleon - such as the Smith's dwarf chameleon - use their color-changing ability to blend in with their surroundings, as an effective form of camouflage.[9]
Color change is also used as an expression of the physiological condition of the lizard, and as a social indicator to other chameleons. Some research suggests that social signalling was the primary driving force behind the evolution of color change, and that camouflage evolved as a secondary concern.[10][11]
Chameleons have specialized cells, collectively called chromatophores, that lie in layers under their transparent outer skin. The cells in the upper layer, called xanthophores and erythrophores, contain yellow and red pigments respectively. Below these is another layer of cells called iridophores or guanophores, and they contain the colorless crystalline substance guanine. These are particularly strong reflectors of the blue part of incident light. If the upper layer of chromatophores appears mainly yellow, the reflected light becomes green (blue plus yellow). A layer of dark melanin contained in melanophores is situated even deeper under the reflective iridophores. The melanophores determine the 'lightness' of the reflected light. These specialized cells are full of pigment granules, which are located in their cytoplasm. Dispersion of the pigment granules in the cell grants the intensity of appropriate color. If the pigment is equally distributed in the cell, the whole cell has the intensive color, which depends on the type of chromatophore cell. If the pigment is located only in the centre of the cell, cell appears to be transparent. All these pigment cells can rapidly relocate their pigments, thereby influencing the color of the chameleon.
6/7/10 Armadillo
Armadillos belong to the order Cingulata of the family Dasypodidae and are most closely related to sloths and anteaters. Their distinctive armor plating is made up of actual bones, making the armadillo rather inflexible. This outer “armor” is used more as a deterrent to predators, rather than an actual means of defense. Only the 3-Banded Armadillo can roll itself into a ball for protection, all of the other 19 species use their speed and incredible digging abilities to escape becoming a meal.
With their stubby, powerful legs and strong claws, armadillos are designed for digging and do so constantly. They dig numerous burrows and bolt-holes and can interlink them with an extensive network of semi-permanent tunnels. Armadillos also dig for food, probing the ground and rotting trees for insects, grubs, and other invertebrates, including ants. Armadillos will eat carrion, eggs and even baby birds or other small mammals if the opportunity presents itself.
It is this penchant for digging that has caused the armadillo to be considered destructive and a pest by humans. On the contrary, armadillos frequently consume the insects that cause the most damage to crops and lawns. It is humans, their cars and their pets, which have had a decimating effect on the overall armadillo population. Only the 9-Banded Armadillo has increased its range from South America to as far north as Kansas. Armadillos prefer habitats with sandy soils and can be found in grasslands, woodlands, wetlands and areas of thorny scrub.
When it comes to reproduction, the 9-Banded Armadillo is rather unique. After mating in July, the fertilized egg remains dormant until November. This is called delayed implantation. Once implanted, the single egg then divides into genetically identical quadruplets which will be born 4 months later. The kits are born fully developed except for their boney shells. It will take several weeks for their pink leathery skin to be ossified into armor.
Fun Armadillo Facts
- The armadillo is the state small mammal of Texas.
- Armadillo comes from the Spanish, meaning “little armored one.”
- Armadillos are one of the few animals who consume fire ants as part of their diet. Such an ability can make armadillos very beneficial to humans.
- Besides being excellent diggers, armadillos are also good swimmers. Armadillos can hold their breath for up to 6 minutes.
- Armadillos have poor eyesight and so can be easily startled while foraging.
- If they can’t dig under it, armadillos will climb over it and are quite capable of scaling fences and trees.
References
Armadillo online
Texas Parks & Recreation
The Humane Society of the United States
.
With their stubby, powerful legs and strong claws, armadillos are designed for digging and do so constantly. They dig numerous burrows and bolt-holes and can interlink them with an extensive network of semi-permanent tunnels. Armadillos also dig for food, probing the ground and rotting trees for insects, grubs, and other invertebrates, including ants. Armadillos will eat carrion, eggs and even baby birds or other small mammals if the opportunity presents itself.
It is this penchant for digging that has caused the armadillo to be considered destructive and a pest by humans. On the contrary, armadillos frequently consume the insects that cause the most damage to crops and lawns. It is humans, their cars and their pets, which have had a decimating effect on the overall armadillo population. Only the 9-Banded Armadillo has increased its range from South America to as far north as Kansas. Armadillos prefer habitats with sandy soils and can be found in grasslands, woodlands, wetlands and areas of thorny scrub.
When it comes to reproduction, the 9-Banded Armadillo is rather unique. After mating in July, the fertilized egg remains dormant until November. This is called delayed implantation. Once implanted, the single egg then divides into genetically identical quadruplets which will be born 4 months later. The kits are born fully developed except for their boney shells. It will take several weeks for their pink leathery skin to be ossified into armor.
Fun Armadillo Facts
- The armadillo is the state small mammal of Texas.
- Armadillo comes from the Spanish, meaning “little armored one.”
- Armadillos are one of the few animals who consume fire ants as part of their diet. Such an ability can make armadillos very beneficial to humans.
- Besides being excellent diggers, armadillos are also good swimmers. Armadillos can hold their breath for up to 6 minutes.
- Armadillos have poor eyesight and so can be easily startled while foraging.
- If they can’t dig under it, armadillos will climb over it and are quite capable of scaling fences and trees.
References
Armadillo online
Texas Parks & Recreation
The Humane Society of the United States
.
5/3/10 Sea Lion
There are actually seven species of Sea Lions in the world, but people tend to lump them all into one category. They all belong to a group of animals known as pinnipeds.
Sea Lions are very interesting animals that can end up being extremely large. The males are much bigger than the females which helps them to gain the ability to mate with them because the females will look for the largest males out there to be with.
Sea Lions are found in bodies of water all over the world, but not in the Atlantic Ocean. Many researchers find this to be a very interesting fact. Yet they can’t pinpoint reasons why this is the case. The temperatures are compatible with where some Sea Lions live. There is also plenty of the food that they consume found there.
Some species of Sea Lions live in the sub arctic areas while others live in warmer climates including California. They have long torpedo shaped bodies that are well designed for movements both in the water and on land. All species of Sea Lions are considered to be mammals. This is because they give live birth to their young and the females also nurse the pups with milk they produce in their bodies.
Sea Lions really only have two predators that are other animals – Killer Whales and Sharks. The threat that they pose depend on the areas where the Sea Lions live. When they have to go further out into the waters to find food then they are more likely to encounter such predators. Man has proven to be the biggest threat to the Sea Lion survival though for a very long time.
We really only know the basics about Sea Lions including their anatomy and their mating habits. We do know that they are very social animals and that they have a variety of methods of communicating. Yet we really don’t know much about what those different types of sounds are used for.
They often are found in extremely large colonies. For their protection they will stay very close together both on land and in the water. The big colonies though also have many sub groups found within them. It is common for Sea Lions to move from one sub group to another during various stages of their lives.
For example the males are more likely to be loners. They will form harems when it is time to mate that last for several months. When the larger colonies form again those females with offspring are more likely to stay together. Once the pups are about a year old they tend to form small sub groups as well.
Sea Lions are considered to be highly intelligent animals. They have been used to teach tricks to for entertainment. They have also been trained to help the United States Navy with their in water needs. For the most part they are considered to be very timid but there have been some reports of aggressive attacks on humans. The males are extremely aggressive when it comes to earning the right to mate with females.
The future is unsure for many species of Sea Lions. Years of them being destroyed by humans has really taken a toll on them. Environmental concerns continue to cause problems for them in their natural habitats as well. The fact that humans are also taking control over the waters where they once lived in peace is a huge concern. Even with conservation efforts in place there is still a great deal of work to be done if these animals are going to survive.
Sea Lion Species
Sea Lion Species
Sea Lions are very interesting animals that can end up being extremely large. The males are much bigger than the females which helps them to gain the ability to mate with them because the females will look for the largest males out there to be with.
Sea Lions are found in bodies of water all over the world, but not in the Atlantic Ocean. Many researchers find this to be a very interesting fact. Yet they can’t pinpoint reasons why this is the case. The temperatures are compatible with where some Sea Lions live. There is also plenty of the food that they consume found there.
Some species of Sea Lions live in the sub arctic areas while others live in warmer climates including California. They have long torpedo shaped bodies that are well designed for movements both in the water and on land. All species of Sea Lions are considered to be mammals. This is because they give live birth to their young and the females also nurse the pups with milk they produce in their bodies.
Sea Lions really only have two predators that are other animals – Killer Whales and Sharks. The threat that they pose depend on the areas where the Sea Lions live. When they have to go further out into the waters to find food then they are more likely to encounter such predators. Man has proven to be the biggest threat to the Sea Lion survival though for a very long time.
We really only know the basics about Sea Lions including their anatomy and their mating habits. We do know that they are very social animals and that they have a variety of methods of communicating. Yet we really don’t know much about what those different types of sounds are used for.
They often are found in extremely large colonies. For their protection they will stay very close together both on land and in the water. The big colonies though also have many sub groups found within them. It is common for Sea Lions to move from one sub group to another during various stages of their lives.
For example the males are more likely to be loners. They will form harems when it is time to mate that last for several months. When the larger colonies form again those females with offspring are more likely to stay together. Once the pups are about a year old they tend to form small sub groups as well.
Sea Lions are considered to be highly intelligent animals. They have been used to teach tricks to for entertainment. They have also been trained to help the United States Navy with their in water needs. For the most part they are considered to be very timid but there have been some reports of aggressive attacks on humans. The males are extremely aggressive when it comes to earning the right to mate with females.
The future is unsure for many species of Sea Lions. Years of them being destroyed by humans has really taken a toll on them. Environmental concerns continue to cause problems for them in their natural habitats as well. The fact that humans are also taking control over the waters where they once lived in peace is a huge concern. Even with conservation efforts in place there is still a great deal of work to be done if these animals are going to survive.
Sea Lion Species
Sea Lion Species
4/5/10 Rabbit
In honor of Spring, Easter, and the new movie Alice In Wonderland, our animal of the month is the WhiteRabbit!
Rabbits are small mammals in the family Leporidae of the order Lagomorpha, found in several parts of the world. There are seven different genera in the family classified as rabbits, including the European rabbit (Oryctolagus cuniculus), Cottontail rabbit (genus Sylvilagus; 13 species), and the Amami rabbit (Pentalagus furnessi, endangered species on Amami Ōshima, Japan). There are many other species of rabbit, and these, along with pikas and hares, make up the order Lagomorpha.
Location and habitat:
Entrance to a rabbit burrow with rabbit droppings near entrance The rabbit lives in many areas around the world. Rabbits live in groups, and the best known species, the European rabbit lives in underground burrows, or rabbit holes. A group of burrows is called a warren. [1] Meadows, woods, forests, thickets, and grasslands are areas in which rabbits live.[1] They also inhabit deserts and wetlands. More than half the world's rabbit population resides in North America.[1] They also live in Europe, India, Sumatra, Japan, and parts of Africa. The European rabbit has been introduced to many places around the world.[2]
Characteristics and anatomy:
The rabbit's long ears, which can be more than 10 cm (4 in) long, are probably an adaptation for detecting predators. They have large, powerful hind legs. Each foot has five toes, with one greatly reduced in size. They are digitigrade animals; they move around on the tips of their toes. Wild rabbits do not differ much in their body proportions or stance, with full, egg-shaped bodies. Their size can range anywhere from 20 cm (8 in) in length and 0.4 kg in weight to 50 cm (20 in) and more than 2 kg. The fur is most commonly long and soft, with colors such as shades of brown, gray, and buff. The tail is a little plume of brownish fur (white on top for cottontails).[2]
Rabbits have two sets of incisor teeth, one behind the other. This way they can be distinguished from rodents, with which they are often mistaken.[5]
Behavior:
A rabbit's side view Rabbits, being prey animals, tend to be exploratory in new spaces and when confronted with a threat, they tend to freeze and observe. Rabbit vision has a remarkably wide field of vision, and a good deal of it is devoted to overhead scanning. Even indoors, rabbits will scan for overhead threats.
Rabbits have a complex social structure, and like dogs, will attempt to establish a hierarchy and dominance.
Diseases Differences from hares Main article: Hare Rabbits are clearly distinguished from hares in that rabbits are altricial, having young that are born blind and hairless. In contrast, hares are generally born with hair and are able to see (precocial). All rabbits except the cottontail rabbit live underground in burrows or warrens, while hares live in simple nests above the ground (as does the cottontail rabbit), and usually do not live in groups. Hares are generally larger than rabbits, with longer ears, and have black markings on their fur. Hares have not been domesticated, while European rabbits are often kept as house pets. In gardens, they are typically kept in hutches — small, wooden, house-like boxes — that protect the rabbits from the environment and predators.
As pets Main article: House rabbit Oryctolagus cuniculus Pet rabbits kept indoors are referred to as house rabbits. House rabbits typically have an indoor pen or cage and a rabbit-safe place to run and exercise, such as an exercise pen, living room or family room. Rabbits can be trained to use a litter box and some can learn to come when called. Domestic rabbits that do not live indoors can also often serve as companions for their owners, typically living in an easily accessible hutch outside the home. Some pet rabbits live in outside hutches during the day for the benefit of fresh air and natural daylight and are brought inside at night.
Whether indoor or outdoor, pet rabbits' pens are often equipped with enrichment activities such as shelves, tunnels, balls, and other toys. Pet rabbits are often provided additional space in which to get exercise, simulating the open space a rabbit would traverse in the wild. Exercise pens or lawn pens are often used to provide a safe place for rabbits to run.
A pet rabbit's diet typically consists of unlimited Timothy hay, a small amount of pellets, and a small portion of fresh vegetables. Rabbits are social animals. Rabbits as pets can find their companionship with a variety of creatures, including humans, other rabbits, guinea pigs, and sometimes even cats and dogs. Animal welfare organisations such as the House Rabbit Society recommend that rabbits do not make good pets for small children because children generally do not know how to stay quiet, calm, and gentle around rabbits. As prey animals, rabbits are alert, timid creatures that startle easily. They have fragile bones, especially in their backs, that require support on the belly and bottom when picked up. Children 7 years old and older usually have the maturity required to care for a rabbit.[10]
As food and clothing See also: Domestic rabbit An Australian 'Rabbiter' circa 1900 A load of rabbit skins, Northern Tablelands, New South Wales Rabbits may be slaughtered commercially for their meat. Leporids such as European rabbits and hares are a food meat in Europe, South America, North America, some parts of the Middle East, and China, among other places.
Rabbit is still commonly sold in UK butchers and markets, although not frequently in supermarkets. At farmers markets and the famous Borough Market in London, rabbits will be displayed dead and hanging unbutchered in the traditional style next to braces of pheasant and other small game. Rabbit meat was once commonly sold in Sydney, Australia, the sellers of which giving the name to the rugby league team the South Sydney Rabbitohs, but quickly became unpopular after the disease myxomatosis was introduced in an attempt to wipe out the feral rabbit population (see also Rabbits in Australia).
When used for food, rabbits are both hunted and bred for meat. Snares or guns along with dogs are usually employed when catching wild rabbits for food. In many regions, rabbits are also bred for meat, a practice called cuniculture. Rabbits can then be killed by hitting the back of their heads, a practice from which the term rabbit punch is derived. Rabbit meat is a source of high quality protein.[11] It can be used in most ways chicken meat is used. In fact, well-known chef Mark Bittman says that domesticated rabbit tastes like chicken because both are blank palettes upon which any desired flavors can be layered.[12] Rabbit meat is leaner than beef, pork, and chicken meat. Rabbit products are generally labeled in three ways, the first being Fryer. This is a young rabbit between 4.5 and 5 pounds and up to 9 weeks in age.[13] This type of meat is tender and fine grained. The next product is a Roaster; they are usually over 5 pounds and up to 8 months in age. The flesh is firm and coarse grained and less tender than a fryer. Then there are giblets which include the liver and heart. One of the most common types of rabbit to be bred for meat is New Zealand white rabbit.
There are several health issues associated with the use of rabbits for meat, one of which is Tularemia or Rabbit Fever.[14] Another is so-called rabbit starvation, due most likely to essential fatty acid deficiencies in rabbit meat and synthesis limitations in human beings.
Rabbits are a favorite food item of large pythons, such as Burmese pythons and reticulated pythons, both in the wild, as well as pet pythons. A typical diet for example, for a pet Burmese python, is a rabbit once a week.[citation needed]
Rabbit pelts are sometimes used for clothing and accessories, such as scarves or hats. Angora rabbits are bread for their long, fine hair, which can be sheared and harvested like sheep wool. Rabbits are very good producers of manure; additionally, their urine, being high in nitrogen, makes lemon trees very productive. Their milk may also be of great medicinal or nutritional benefit due to its high protein content.[citation needed]
Environmental problems:
When introduced to a new area, rabbits can quickly overpopulate and become a nuisance, as they have on this university campus. A European Rabbit afflicted by Myxomatosis in England See also: Rabbits in Australia Rabbits have been a source of environmental problems when introduced into the wild by humans. As a result of their appetites, and the rate at which they breed, wild rabbit depredation can be problematic for agriculture. Gassing, barriers (fences), shooting, snaring, and ferreting have been used to control rabbit populations, but the most effective measures are diseases such as myxomatosis (myxo or mixi, colloquially) and calicivirus. In Europe, where rabbits are farmed on a large scale, they are protected against myxomatosis and calicivirus with a genetically modified virus. The virus was developed in Spain, and is beneficial to rabbit farmers. If it were to make its way into wild populations in areas such as Australia, it could create a population boom, as those diseases are the most serious threats to rabbit survival. Rabbits in Australia are considered to be such a pest that land owners are legally obliged to control them.[citation needed]
In culture and literature:
See also: List of fictional rabbits Rabbits are often used as a symbol of fertility or rebirth, and have long been associated with spring and Easter as the Easter Bunny. The species' role as a prey animal also lends itself as a symbol of innocence, another Easter connotation.
Additionally, rabbits are often used as symbols of playful sexuality, which also relates to the human perception of innocence, as well as its reputation as a prolific breeder.
Further information:
Folklore and mythology:
The rabbit often appears in folklore as the trickster archetype, as he uses his cunning to outwit his enemies.
Other fictional rabbits:
Main article: List of fictional rabbits The rabbit as trickster appears in American popular culture; for example the Br'er Rabbit character from African-American folktales and Disney animation; and the Warner Bros. cartoon character Bugs Bunny.
Anthropomorphized rabbits have appeared in a host of works of film, literature, and technology, notably the White Rabbit and the March Hare in Lewis Carroll's Alice's Adventures in Wonderland; in the popular novels Watership Down, by Richard Adams (which has also been made into a movie) and Rabbit Hill by Robert Lawson, as well as in Beatrix Potter's Peter Rabbit stories.
Urban legends:
Main article: Rabbit test It was commonly believed that pregnancy tests were based on the idea that a rabbit would die if injected with a pregnant woman's urine. This is not true. However, in the 1920s it was discovered that if the urine contained the hCG, a hormone found in the bodies of pregnant women, the rabbit would display ovarian changes. The rabbit would then be killed to have its ovaries inspected, but the death of the rabbit was not the indicator of the results. Later revisions of the test allowed technicians to inspect the ovaries without killing the animal. A similar test involved injecting Xenopus frogs to make them lay eggs, but animal tests for pregnancy have been made obsolete by faster, cheaper, and simpler modern methods.
Rabbits are small mammals in the family Leporidae of the order Lagomorpha, found in several parts of the world. There are seven different genera in the family classified as rabbits, including the European rabbit (Oryctolagus cuniculus), Cottontail rabbit (genus Sylvilagus; 13 species), and the Amami rabbit (Pentalagus furnessi, endangered species on Amami Ōshima, Japan). There are many other species of rabbit, and these, along with pikas and hares, make up the order Lagomorpha.
Location and habitat:
Entrance to a rabbit burrow with rabbit droppings near entrance The rabbit lives in many areas around the world. Rabbits live in groups, and the best known species, the European rabbit lives in underground burrows, or rabbit holes. A group of burrows is called a warren. [1] Meadows, woods, forests, thickets, and grasslands are areas in which rabbits live.[1] They also inhabit deserts and wetlands. More than half the world's rabbit population resides in North America.[1] They also live in Europe, India, Sumatra, Japan, and parts of Africa. The European rabbit has been introduced to many places around the world.[2]
Characteristics and anatomy:
The rabbit's long ears, which can be more than 10 cm (4 in) long, are probably an adaptation for detecting predators. They have large, powerful hind legs. Each foot has five toes, with one greatly reduced in size. They are digitigrade animals; they move around on the tips of their toes. Wild rabbits do not differ much in their body proportions or stance, with full, egg-shaped bodies. Their size can range anywhere from 20 cm (8 in) in length and 0.4 kg in weight to 50 cm (20 in) and more than 2 kg. The fur is most commonly long and soft, with colors such as shades of brown, gray, and buff. The tail is a little plume of brownish fur (white on top for cottontails).[2]
Rabbits have two sets of incisor teeth, one behind the other. This way they can be distinguished from rodents, with which they are often mistaken.[5]
Behavior:
A rabbit's side view Rabbits, being prey animals, tend to be exploratory in new spaces and when confronted with a threat, they tend to freeze and observe. Rabbit vision has a remarkably wide field of vision, and a good deal of it is devoted to overhead scanning. Even indoors, rabbits will scan for overhead threats.
Rabbits have a complex social structure, and like dogs, will attempt to establish a hierarchy and dominance.
Diseases Differences from hares Main article: Hare Rabbits are clearly distinguished from hares in that rabbits are altricial, having young that are born blind and hairless. In contrast, hares are generally born with hair and are able to see (precocial). All rabbits except the cottontail rabbit live underground in burrows or warrens, while hares live in simple nests above the ground (as does the cottontail rabbit), and usually do not live in groups. Hares are generally larger than rabbits, with longer ears, and have black markings on their fur. Hares have not been domesticated, while European rabbits are often kept as house pets. In gardens, they are typically kept in hutches — small, wooden, house-like boxes — that protect the rabbits from the environment and predators.
As pets Main article: House rabbit Oryctolagus cuniculus Pet rabbits kept indoors are referred to as house rabbits. House rabbits typically have an indoor pen or cage and a rabbit-safe place to run and exercise, such as an exercise pen, living room or family room. Rabbits can be trained to use a litter box and some can learn to come when called. Domestic rabbits that do not live indoors can also often serve as companions for their owners, typically living in an easily accessible hutch outside the home. Some pet rabbits live in outside hutches during the day for the benefit of fresh air and natural daylight and are brought inside at night.
Whether indoor or outdoor, pet rabbits' pens are often equipped with enrichment activities such as shelves, tunnels, balls, and other toys. Pet rabbits are often provided additional space in which to get exercise, simulating the open space a rabbit would traverse in the wild. Exercise pens or lawn pens are often used to provide a safe place for rabbits to run.
A pet rabbit's diet typically consists of unlimited Timothy hay, a small amount of pellets, and a small portion of fresh vegetables. Rabbits are social animals. Rabbits as pets can find their companionship with a variety of creatures, including humans, other rabbits, guinea pigs, and sometimes even cats and dogs. Animal welfare organisations such as the House Rabbit Society recommend that rabbits do not make good pets for small children because children generally do not know how to stay quiet, calm, and gentle around rabbits. As prey animals, rabbits are alert, timid creatures that startle easily. They have fragile bones, especially in their backs, that require support on the belly and bottom when picked up. Children 7 years old and older usually have the maturity required to care for a rabbit.[10]
As food and clothing See also: Domestic rabbit An Australian 'Rabbiter' circa 1900 A load of rabbit skins, Northern Tablelands, New South Wales Rabbits may be slaughtered commercially for their meat. Leporids such as European rabbits and hares are a food meat in Europe, South America, North America, some parts of the Middle East, and China, among other places.
Rabbit is still commonly sold in UK butchers and markets, although not frequently in supermarkets. At farmers markets and the famous Borough Market in London, rabbits will be displayed dead and hanging unbutchered in the traditional style next to braces of pheasant and other small game. Rabbit meat was once commonly sold in Sydney, Australia, the sellers of which giving the name to the rugby league team the South Sydney Rabbitohs, but quickly became unpopular after the disease myxomatosis was introduced in an attempt to wipe out the feral rabbit population (see also Rabbits in Australia).
When used for food, rabbits are both hunted and bred for meat. Snares or guns along with dogs are usually employed when catching wild rabbits for food. In many regions, rabbits are also bred for meat, a practice called cuniculture. Rabbits can then be killed by hitting the back of their heads, a practice from which the term rabbit punch is derived. Rabbit meat is a source of high quality protein.[11] It can be used in most ways chicken meat is used. In fact, well-known chef Mark Bittman says that domesticated rabbit tastes like chicken because both are blank palettes upon which any desired flavors can be layered.[12] Rabbit meat is leaner than beef, pork, and chicken meat. Rabbit products are generally labeled in three ways, the first being Fryer. This is a young rabbit between 4.5 and 5 pounds and up to 9 weeks in age.[13] This type of meat is tender and fine grained. The next product is a Roaster; they are usually over 5 pounds and up to 8 months in age. The flesh is firm and coarse grained and less tender than a fryer. Then there are giblets which include the liver and heart. One of the most common types of rabbit to be bred for meat is New Zealand white rabbit.
There are several health issues associated with the use of rabbits for meat, one of which is Tularemia or Rabbit Fever.[14] Another is so-called rabbit starvation, due most likely to essential fatty acid deficiencies in rabbit meat and synthesis limitations in human beings.
Rabbits are a favorite food item of large pythons, such as Burmese pythons and reticulated pythons, both in the wild, as well as pet pythons. A typical diet for example, for a pet Burmese python, is a rabbit once a week.[citation needed]
Rabbit pelts are sometimes used for clothing and accessories, such as scarves or hats. Angora rabbits are bread for their long, fine hair, which can be sheared and harvested like sheep wool. Rabbits are very good producers of manure; additionally, their urine, being high in nitrogen, makes lemon trees very productive. Their milk may also be of great medicinal or nutritional benefit due to its high protein content.[citation needed]
Environmental problems:
When introduced to a new area, rabbits can quickly overpopulate and become a nuisance, as they have on this university campus. A European Rabbit afflicted by Myxomatosis in England See also: Rabbits in Australia Rabbits have been a source of environmental problems when introduced into the wild by humans. As a result of their appetites, and the rate at which they breed, wild rabbit depredation can be problematic for agriculture. Gassing, barriers (fences), shooting, snaring, and ferreting have been used to control rabbit populations, but the most effective measures are diseases such as myxomatosis (myxo or mixi, colloquially) and calicivirus. In Europe, where rabbits are farmed on a large scale, they are protected against myxomatosis and calicivirus with a genetically modified virus. The virus was developed in Spain, and is beneficial to rabbit farmers. If it were to make its way into wild populations in areas such as Australia, it could create a population boom, as those diseases are the most serious threats to rabbit survival. Rabbits in Australia are considered to be such a pest that land owners are legally obliged to control them.[citation needed]
In culture and literature:
See also: List of fictional rabbits Rabbits are often used as a symbol of fertility or rebirth, and have long been associated with spring and Easter as the Easter Bunny. The species' role as a prey animal also lends itself as a symbol of innocence, another Easter connotation.
Additionally, rabbits are often used as symbols of playful sexuality, which also relates to the human perception of innocence, as well as its reputation as a prolific breeder.
Further information:
Folklore and mythology:
The rabbit often appears in folklore as the trickster archetype, as he uses his cunning to outwit his enemies.
- In Aztec mythology, a pantheon of four hundred rabbit gods known as Centzon Totochtin, led by Ometotchtli or Two Rabbit, represented fertility, parties, and drunkenness.
- In Central Africa "Kalulu" the rabbit is widely known as a tricky character, getting the better of bargains.[citation needed]
- In Chinese literature, rabbits accompany Chang'e on the Moon. Also associated with the Chinese New Year (or Lunar New Year), rabbits are also one of the twelve celestial animals in the Chinese Zodiac for the Chinese calendar. It is interesting to note that the Vietnamese lunar new year replaced the rabbit with a cat in their calendar, as rabbits did not inhabit Vietnam.
- In the folklore of the United States, a rabbit's foot is frequently carried as an amulet, and is often used on keychains, where it is thought to bring luck. The practice derives from the system of African-American folk magic called hoodoo.
- In Japanese tradition, rabbits live on the Moon where they make mochi, the popular snack of mashed sticky rice. This comes from interpreting the pattern of dark patches on the moon as a rabbit standing on tiptoes on the left pounding on an usu, a Japanese mortar (See also: Moon rabbit).
- In Jewish folklore, rabbits (shfanim שפנים) are associated with cowardice, a usage still current in contemporary Israeli spoken Hebrew (similar to English colloquial use of "chicken" to denote cowardice).
- A Korean myth similar to the Japanese counterpart presents rabbits living on the moon making rice cakes (Tteok in Korean).
- In Native American Ojibwe mythology, Nanabozho, or Great Rabbit, is an important deity related to the creation of the world.
- A Vietnamese mythological story portrays the rabbit of innocence and youthfulness. The Gods of the myth are shown to be hunting and killing rabbits to show off their power.
- "Taushan Tepe" (Rabbit Hill) was the Turkish name of Kabile, Bulgaria.
Other fictional rabbits:
Main article: List of fictional rabbits The rabbit as trickster appears in American popular culture; for example the Br'er Rabbit character from African-American folktales and Disney animation; and the Warner Bros. cartoon character Bugs Bunny.
Anthropomorphized rabbits have appeared in a host of works of film, literature, and technology, notably the White Rabbit and the March Hare in Lewis Carroll's Alice's Adventures in Wonderland; in the popular novels Watership Down, by Richard Adams (which has also been made into a movie) and Rabbit Hill by Robert Lawson, as well as in Beatrix Potter's Peter Rabbit stories.
Urban legends:
Main article: Rabbit test It was commonly believed that pregnancy tests were based on the idea that a rabbit would die if injected with a pregnant woman's urine. This is not true. However, in the 1920s it was discovered that if the urine contained the hCG, a hormone found in the bodies of pregnant women, the rabbit would display ovarian changes. The rabbit would then be killed to have its ovaries inspected, but the death of the rabbit was not the indicator of the results. Later revisions of the test allowed technicians to inspect the ovaries without killing the animal. A similar test involved injecting Xenopus frogs to make them lay eggs, but animal tests for pregnancy have been made obsolete by faster, cheaper, and simpler modern methods.