Polar Bear - Ecology & Habitat

Polar bears are found throughout the circumpolar Arctic on pack ice, along or near coasts, and on islands. They share this habitat with indigenous peoples, and animals such as ringed seals, arctic foxes, narwhal, beluga whales, and millions of migratory birds.

Life Cycle
During November and December, the female digs a maternity den in a drift of snow, maintaining and enlarging the chamber as the drifts cover her, snowing her in. Soon she gives birth, often to twins, which cuddle in their mother's thick fur. Females cease to feed throughout the winter and instead lives off their stored fat. Their milk, high in fat content, enables the cubs to keep warm and grow rapidly before leaving the dark den in March or April.

Short trips are made to and from the den for several days as the cubs acclimate to the outside temperatures. Then the family leaves and makes its way to the sea ice where the mother feeds and protects her cubs. The family remains together during the following spring and summer. After two years together, the family disperses.

Breeding
Polar bears breed in late March, April and May. The males actively seek out females by following their tracks and smell. They remain with the female only for a short time.

Diet
A healthy diet for polar bears consists of about 2 kg (4.4 lbs) of fat per day. They prey on ringed seals, species with high body fat content, by breaking into seal dens, which are dug in snow mounds on the sea ice between late April and mid-July, and by catching seals on the sea ice or as they emerge from the water.

The seal dens, or lairs, are not visible from above, but seeing is less important than smelling and hearing to a polar bear. With their keen sense of smell, they can detect the seals in their lairs beneath the snow and ice.

When in position, they pounce through the snow to catch the seal before it slips into the water through its hole in the ice. On the open ice, polar bears creep next to a breathing hole and stay completely still, lying on their stomach and chest with their chin on the ice, waiting patiently for a seal to appear - often for several hours.

Plentiful access to food in this period is critical, particularly for pregnant females. As the southern edge of the arctic ice cap melts in summer, some polar bears are stranded on land and spend their summers fasting (up to three of four months), living off body fat stored from hunting in the spring and winter.

Polar bears also prey upon harp seals, as well as young walruses and beluga whales, narwhal, fish, and seabirds and their eggs. Near human settlements where there are open garbage dumps, polar bears can be found scavenging for food.