POLAR BEARS

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what is a polar bear?

A polar bears is a very heavy and big animal it lives in the arctic near the north pole and is the cutest animal in the world.

How much do polar bears weigh?

Polar bears when adults weigh as much as two gorillas or 400kg. Adult male polar bears weigh from 775 to 1,200 pounds. A few weigh more than 1,200 pounds, but these individuals would be exceptional. Females normally weigh 330 to 650 pounds. It's not uncommon for female polar bears preparing to enter maternity dens in the fall to weigh over 600 pounds.

How tall are polar bears?

When polar bears are standing on there hind legs they are tall enough to look an elephant in the eyes.

What do polar bears eat?

The polar bear's main prey is the ringed seal.

Where do polar bears live?

Polar bears live in the northen areas. They are found in Canada (home to roughly 60% of the world's polar bears), the U.S. (Alaska), Greenland, Russia, and Norway. Scientists have identified 19 populations of polar bears living in four different ice regions in the Arctic.



Characteristics

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Fur

Polar bears fur consists of anundercoat topped by guard hairs of various lengths. It is not actually white—it just looks that way.

Each hair shaft is pigment-free and transparent with a hollow core that scatters and reflects visible light, much like what happens with ice and snow.

Polar bears look whitest when they are clean and in sunlight, especially just after the molt period, which usually begins in spring and is complete by late summer.

claws

Claws

Polar bear claws are thick and curved, sharp and strong. Each can measure more than 5.1 centimetres long. Bears use their claws to catch and hold prey.


Habits and Behaviour

Hunting and Eating

Polar bears locate breathing holes with their powerful sense of smell and lie in wait for the seals to rise. Polar bears have to be smart and patient because the wait can be long—from hours to days.

Seal stalking. Bears also stalk ringed seals that are basking on the ice by taking advantage of their sleep-wake rhythms. The bear crawls slowly forward and freezes in place when the animal raises its head. At about 20 feet from the seal, the bear pounces, killing the seal before it can escape back into the sea.

Polar bears depend on ice for access to their main prey.

Polar bears' lives are a cycle of feasting and fasting. When hunting is good, polar bears eat only the seal's blubber and skin. They can eat 100 pounds of blubber in a single sitting! Younger, less experienced bears devour the remains.

In summer, when ice floes retreat, some polar bears follow the ice—sometimes traveling hundreds of miles—to stay with their food source.

•Polar bears stranded on land in summer must stay put until the ice forms again in fall. On land, bears face lean times. They rarely catch seals in open water.

The polar bear is an opportunistic hunter, always alert to other food sources.Other arctic marine mammals, including whales, walruses, and narwhals, do provide adequate nutrition for hungry polar bears. Beluga whales or narwhals that become trapped in a small opening in pack ice become easy prey for the bears. And whale carcasses on the shore offer a bonanza.

Walking and Running

Walking

Polar bears walk at about five to six km per hour. Females with small cubs slow their speed to two and a half to four km per hour.

Polar bears are well known for their slow, plodding stroll. They are able to gallop as fast as a horse over short distances, but they prefer to amble leisurely.

Norwegian scientist Nils Oritsland showed that polar bears expend more than twice the energy of most other mammals when walking or running—probably because their bodies are so bulky.

Walking bears expend 13 times more energy than resting bears. This explains their preference for still-hunting.

Running

Polar bears can run as fast as 40 km per hour—but only for short distances. Younger, leaner bears are the best runners. They can cover two km without stopping. Older, larger bears quickly overheat.

Communicating

Polar bears use a combination of body language and vocalizations to communicate.

•Head wagging from side to side often occurs when polar bears want to play. Adult bears initiate play by standing on their hind legs, chin lowered to their chests, and front paws hanging by their sides

•Nose-to-nose greetings are the way a bear asks another bear for something, such as food.

•Chuffing sounds are a response to stress, often heard when a mother bear is worried for her cubs' safety.

•Hissing and snorting and a lowered head all signify aggression.

•Loud roars or growls communicate anger.

•Deep growls are warnings, perhaps in defence of a food source.

•Attacking polar bears charge forward with heads down and ears laid back.

•Submissive polar bears always move downwind of dominant bears.

Bathing and cleaning

Bathing

Polar bears like to be clean and dry because matted, dirty, and wet fur is a poor insulator.

In summer, if the bears find something to eat, they feed for 20–30 minutes and then head for open water and spend up to 15 minutes washing off. They also lick their paws and chests.

Polar bears dry themselves by shaking off excess water and by rubbing their fur in the snow.

Cleaning

In winter, polar bears clean themselves with snow instead of water. Bears rub their heads in the snow, push forward on their tummies, and roll on their backs.

Polar bears also remove chunks of ice from their paws to make walking more comfortable.

Mother polar bears lick their cubs to keep them clean. Cubs also lick themselves and each other. After cubs leave the den, they learn how to wash in snow and water.

Sleeping and Bedding

Sleeping

Most polar bears sleep for seven to eight hours at a stretch and they take naps, too. In that way, they're a lot like people.

On the ice in spring and summer, polar bears tend to sleep more during the day than at night, probably because seals are more active at night.

Polar bears nap just about anywhere and anytime, and especially after feeding on a seal. Napping helps bears conserve energy. A polar bear's entire existence centres on hunting and conserving energy.

Bedding

In winter, polar bears sleep in shallow pits they dig in the snow with their sides or backs to the wind.

Polar bears sleep right through blizzards in day beds dug in the lee of a ridge. The snow piles up on top of them and provides a blanket. Sometimes they stay curled up under the snow for several days until the storm passes.

In summer, polar bears curl up on an ice patch, sometimes using a block of ice or an outstretched paw as a pillow. Landlocked bears dig sleeping pits in the sand or in gravel ridges along the shoreline.

Hibernating and Denning

Hibernating

Polar bears remain active throughout the year.

The polar bears that come ashore after the ice melts in Hudson Bay each summer. These bears have no food source and enter a state scientist’s call walking hibernation. Polar bears in this state appear to maintain normal body temperature but are able to save energy by reducing their metabolic rate and recycling proteins.

One study of Hudson Bay polar bears that fed at a garbage dump during iceless months revealed that they did not enter a state of walking hibernation.

Denning

Pregnant polar bears den in the fall after feeding heavily in August and September. They choose den sites in snowdrifts along mountain slopes or hills near sea ice or in banks of snow on the frozen sea. Along Western Hudson Bay mother bears begin by denning in earthen dens along river banks and later move to snow dens.

To build her den, the female scrapes a tunnel into the snow and digs two chambers. She gives birth to one, two, or three cubs in November or December. Twins are most common.

Mother bears do not enter a state of deep hibernation because they need a higher body temperature in order to meet the demands of pregnancy, birth, and nursing.

When the mother bear emerges from her den in March or April, she is in a state similar to that of a denning black bear. Her body temperature, however, is higher, ranging from 35º to 37º C compared with 31º to 35º C in a black bear.

Adaptation

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human interaction

Polar Bears in Zoos

In zoos, polar bears have been known to turn green due to colonies growing in their hollow hair shafts. This happened at the San Diego Zoo in 1979, with no harm coming to the bears.