The ancient ancestor of all bears, the Dawn bear, first appears in the Miocene fossil record about 20 million years ago. The polar bear is the largest land based carnivore. Unlike its relatives in the bear family, particularly the grizzly from which it descended about 70,000 years ago, it is almost entirely carnivorous.
In the arctic regions the polar bear is undoubtedly at the very top of the food chain. Male polar bears range in length from 2.5 to 3 metres and weigh from 350-800 kilograms. Females are smaller ranging in length from 2 metres to 2.5 metres and in weight from 175 to 300 kilograms. They have heavy, stout bodies with muscular legs and necks which are longer than those of their brown bear cousins. The long neck helps them to keep their heads out of the water when swimming. Their feet are partially webbed between the toes which also aids in swimming. They can swim for over sixty miles without resting at a constant speed of about six miles per hour. They are not as quick on land as brown bears but can run at up to twenty-five miles per hour for short distances.
They are uniquely adapted to life in the arctic environment. Thick layers of fat and a thick water repellent fur coat provide protection against the low temperatures of the air and water. Only the nose and footpads are without fur. The fur is not white but translucent and scatters light which makes it appear white. [See Beauty: Colour and Colouration] Compared to the black bear and grizzly their ears are also quite small which also helps the prevent loss of body heat. Baby polar bears weigh only 0.25 percent of the adult weight of their mother at birth who feeds them on her milk which is very rich in fat.
Their sharp claws, very useful for traction on the slippery ice, and their intelligence make them good hunters. Their diet is mainly ringed seals supplemented with the occasional bearded seal. They will also scavenge meat from other dead animals. Seals are taken in their dens, breathing holes in the water, or at the waters edge. They are reputed to be very intelligent with some biologists saying they are as intelligent as apes. They can be violently aggressive towards humans and have been known to stalk and kill them. Between 1970-1985 four people were killed and fifteen injured by polar bears in Canada. All four deaths were due to predation by the polar bear.
Sexual maturity of female polar bears is around four or five years old, which is when they first breed, with mating taking place in the late spring (April-June). The gestation period is about eight months and so the polar ear cubs, numbering one to three, are usually born in December or January. The cubs remain with their mothers for over two years though sixty percent of cubs die within their first year.
Polar bears can live for up to twenty-five years. All polar bears are aggressive and male polar bears will occasionally fight one another for access to females and will kill cubs.
Bears figure prominently in the myths of Indians and the Inuit. There are many Inuit myths in which polar bears have sexual intercourse with women. Bears are very human like when they stand on their hind legs or when the carcass is skinned. Many of the arctic peoples think of animals as having ‘personhood’ though being animal and they need to be hunted with respect. For instance, in Greenland, after a polar bear is killed pieces of its skin or vertebrae need to be hung in the wind.
by Michael Sones
