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Polar Bear

Genus: Ursus
Species: maritimus

Polar bears are in serious danger of going extinct due to global warming.

Rising temperatures cause sea ice to melt, especially in the summer months when the polar bears are the most active. Polar bears depend on sea ice as habitat for hunting and dens.

As available sea ice decreases, polar bears have to swim farther to find suitable habitat and it takes much longer to find a meal. Compounding the problem, sea ice loss also impacts polar bears main food source--seals.

Learn more about polar bears and sea ice >>

Polar bears need our help and protection to ensure a long, healthy future for the species. The best way you can help polar bears is by reducing your carbon emissions and working with National Wildlife Federation to campaign for reductions in global warming pollutants.

Description:

Polar bears are large bears. They have strong legs with large, flattened feet that help with walking on ice and swimming. The wide paws prevent sea ice from breaking by distributing weight while the bear is walking. In addition, the wide paws serve as paddles to help polar bears swim faster. They are also partially webbed.

Many of the polar bear's physical adaptations help maintain body heat:

Fur covers the entire body, even the feet, to help keep the bear warm in the bitterly cold climate of the Arctic.
The fur has two layers--one for trapping in heat close to the body and another for trapping heat and repelling water.
The outer layer of fur is hollow and reflects light giving the fur a white color. The white fur helps the bear camouflage in the icy and snowy habitat.
In contrast to the white fur, the skin is black. The black skin more readily absorbs sunlight, which helps to keep the bear warm. A polar bear's tongue is also black.
Polar bears have a layer of blubber below the surface of the skin. The blubber acts as insulation on the body to trap heat. This is especially important while swimming.

Size: Polar bears are one of the largest land mammals on Earth. They're about 7-9 feet long. Male polar bears are much larger than the females. An average male can weigh over a ton – approximately 800-1,500 pounds. The females are usually one-third of the weight of the males, from 300-550 pounds.

Diet: Polar bears are carnivores. They eat ringed and bearded seals, but they have been known to eat walruses, other species of seals, belugas and the carcasses of larger whales. If desperate, a polar bear will eat whatever meat it can find.

Polar bears hunt seals by waiting for the seal to come near the surface of sea ice to breathe. When the seal nears the surface, the polar bear bites or grabs the seal and pulls it onto land to feed. In the Arctic, polar bears are at the top of the food chain.

Typical Lifespan: Polar bears can live to 20-30 years of age.

Habitat: Polar bears mainly live on sea ice. They prefer ice floes, ice edges, islands and can occasionally be found on land. Polar bears are excellent swimmers and they'll travel between ice habitats.

Range: Polar bears are found above the Arctic Circle, and in Alaska and Canada. Polar bears live in Russia, Greenland, Alaska and Canada around the Hudson Bay.

Communication: Polar bears are mainly solitary, except in the breeding season or when the females are raising young. The males may fight over a female. When polar bears communicate, it is in growls or other noises.

Life History and Reproduction: Polar bears breed in the late spring as the temperatures begin to rise in the Arctic. The females are pregnant for about 8 months. During this time, they eat a lot to store up energy to survive the winter with the cubs.

In the beginning of the winter, the female builds a den and awaits the arrival of the cubs. The den is made in a large snow drift either on sea ice or nearby land. In the middle of winter, in some of the coldest places on Earth, female polar bears give birth to cubs. There are usually two cubs, but sometimes one, three or four cubs.

When the cubs are born they are completely dependent on their mother. They stay in the den until the early spring, when they emerge and start exploring the world. In the first year, the cubs eat a mixed diet of breast milk and seal meat caught by their mother. Over time, she teaches her cubs how to hunt as they grow to adult size. The cubs will stay with their mother for close to 3 years before the mother leaves them to begin another breeding cycle.

Polar bears are cautious about breeding in lean times. Breeding and raising cubs takes a lot of energy out of the mother. During years without a lot of available food, polar bears are less likely to breed to avoid risking the death of the cubs or themselves.