Polar Bear, large white bear of the Arctic sea ice, found throughout the Polar Basin, extending southward into Hudson Bay and James Bay of Canada, and along the east coast of Greenland. This bear is more elongated and streamlined for its aquatic life in comparison to land-dwelling bears, but has the typical plantigrade (flat) feet of bears, and five sharp, curved claws for grasping the ice and its prey. Long hair between the pads protects the bears from the cold; stiff hairs on the forelegs, and very broad front feet act as oars when swimming. An extra layer of fat beneath the skin provides further insulation from the cold. All polar bears are white, providing camouflage when hunting, but under different light they may appear brownish, yellow, or even light green.

Polar bears eat berries, sedges, mussels, and kelp, but mostly they eat ringed seals, and occasionally bearded seals, walruses, and white whales. The bears wait by breathing holes in the ice or at the edge of open water and seize the seals as they surface. The largest wild bears ever weighed have been polar bears at more than 800 kg (1,800 lb), but average weights for females are 250 kg (550 lb), and for males about 350 kg (770 lb). The young when born are very small and weigh about 1 kg (2 lb). Polar bears are closely related to brown bears; in fact, they could be considered a white phase of the brown bear, using strict taxonomic rules.

After mating the female makes a den in the snow and will hibernate during the coldest months. Her cubs, usually two, are born in January, nine months after mating. As with other bears, polar bear mothers and young form strong bonds as a result of the helpless state of the cubs at birth. Their eyes remain closed for about 40 days, they must suckle every few hours, and the mothers hold them close to their mammary glands for warmth. The cubs stay with the mother for two years or more. Except for during the breeding season, the males are solitary and walk over endless expanses of sea ice while hunting.

Polar bears stay in individual geographic areas and are constantly on the move as the ice drifts. They have a strong navigational sense, an extremely good sense of smell, and are unusually clever at solving problems in obtaining food. They have little interest in other arctic species, and often ignore people entirely.

During the breeding season (from the end of March through to June) the males fight furiously over females; a male may “corner” a female on a small hill or against a cliff, but each may mate with other bears as well. Most polar bear calls occur in family groups.

Polar bears were hunted extensively in Canada and Greenland, some in Russia, Norway, and Alaska, but since 1973 there have been hunting restrictions. Polar bear populations are relatively secure because few people live in their domain, but shipping and offshore drilling for oil could alter their status drastically worldwide. In addition it is believed that global warming and the subsequent loss of ice—particularly in the Arctic summers and the southern, warmer areas of the Arctic—will affect the polar bear’s own hunting for food, and could seriously reduce numbers.

Scientific classification: Polar bears are in the genus Ursus, the family Ursidae, and they are of the species Ursus maritimus.