Polar Bears

The polar bear (Ursus maritimus) is the largest species of all bears. It is also the largest carnivore on land. The polar bear is a hyper carnivorous bear that is a large bear, approximately the same size as the omnivorous Kodiak bear.

polar bear and her two cubs.
A polar bear family near Baffin Island in the Canadian arctic. Photo credit: John Rollins

Habitat

Polar bears live in the Arctic areas of Alaska, Canada, Russia, Greenland, and Norway. These bears are considered to be marine mammals because they depend on sea ice and the ocean. They spend most of their time in the ocean. Polar bears are nomadic bears and do not mark territories. They travel large distances in search of food and for mating.

Description

Polar bears have a dense undercoat and an outer coat that helps them remain warm in the cold temperatures of the arctic. Their fur and skin are water repellant due to an oil-like substance. The fur can be white or yellow (due to sun oxidation).

Polar bears have a large blubber of fat that’s up to 5 inches thick that acts as another layer of insulation. The blubber, as well as the outer coat, allows the bear to remain buoyant when swimming.

It has large paws and partially webbed toes. The paws of a polar bear are covered in thick fur that is another form of insulation and provides traction when the bear moves around. They have small ears and are known to have great hearing as well as eyesight. They also have an excellent sense of smell and can smell prey that is 20 miles away.

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Adult male polar bears can range from 7 to 11 feet when standing upright, and weigh between 660 to 1,320 pounds. Females range from 6 to 8 feet and weigh between 400 to 700 pounds.

Diet

The polar bear is classified as a carnivorous mammal and feeds mainly on meat. Their favorite food source is the ringed seal. However, they also hunt bearded seals, harbor seals, harp seals, and a variety of other sea animals like walruses and beluga whales.

They usually just feed on blubber and leave the carcasses behind for scavengers. Blubber is better for maintaining their layer of fat for both insulation and storing energy.

Polar bears must kill a seal (or equivalent) every 5 or 6 days to sustain their body weight. A polar bear can sit for hours next to a hole in the ice waiting for a seal to surface.

However, when pack ice melts in the summer, polar bears hunt on land and feed on birds, rodents, eggs, berries, etc.

Reproduction

Polar bears mate once every two to three years betweeen March and July. The female polar bear will dig a den and spend nine months in the den until the cubs are born. There are usually two cubs but sometimes a female can have 1-4 cubs. Cubs are born hairless and without teeth. They are the size of rats at birth. They stay with their mother for about 2 years/

Status

There are an estimated 25,000 to 40,000 polar bears in the world (5,000 more than in 1970). In the wild, polar bears are estimated to live to between 25-30 years. The polar bear was listed as threatened by the United States Department of the Interior on May 14, 2008, under the Endangered Species Act.

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Fun Facts About Polar Bears

  • Polar bears are excellent swimmers and can swim up to 60 miles without rest.
  • Polar bears can swim at depths of 15 to 20 feet.
  • They can stay submerged for over 2 minutes.
  • The largest polar bear on record was over 12′ and weighed 2,210 pounds.
  • Some animals often rely on the remains of polar bear kills as a food source, making the polar bear an important part of the food chain.
  • They can eat up to 150 pounds of food in a single sitting.

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