'Tis the Polar Season!
Polar bears are found in the polar northern hemisphere, including Alaska, Russia, Norway, Greenland and Canada (60% of polar bears live in Canada). Polar bears are direct descendants of the brown bear, and are believed to have evolved about 200,000 years ago when brown bear populations were isolated by glacial ice flows. In order to survive, these isolated northern bears rapidly adapted to the arctic environment. Polar bears now sport coats so efficient in insulation that the bears overheat in temperatures above 10 degrees Fahrenheit. They also have adapted to walking on ice with paws covered in insulating, stiff, traction providing hairs.
Given the scarcity of suitable arctic plant life, polar bears are the most carnivorous members of the bear family. Their favorite food is seal, though they will feed on whales, walruses, rodents, fish, birds, dead sea animals, starfish, and algae as well as berries in the late summer. Their very muscular bodies make them excellent hunters on land and ice and fantastic swimmers in water -- at times they embark on swimming expeditions spanning hundreds of miles. Another adaptive feature of these bears is very large stomachs, capable of holding more than 150 pounds (70 kg) of food. This allows them to go weeks without significant food in the summer and early fall, when the ice melts and they are land stranded.
Female polar bears mate every third spring. No permanent bond is created between the males and females -- the romance only lasts through the mating period. Cubs are born in early winter, small, blind and hairless, in snow caves dug by their mothers. The number of cubs delivered ranges from one to four and averages two per litter. Cubs can open their eyes at about one month old, and are able to walk at one and a half months. The first years of a cub's life are dangerous with threats of starvation, disease or attack. During this period, mothers teach their cubs to hunt, but by the time the cubs are two to three years old, they are left to fend for themselves.
Though the polar bear population had been in decline for years due to over-hunting, the "polar bear nations" successfully enacted legislation to stabilize populations. Scientists estimate today's polar bear population at between 20,000 and 25,000. However, the polar bear's continued existence is still threatened because of shrinking glaciers due to global warming.
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Source: World Wildlife Fund
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