Polar Bear Background and Recovery

Description

Polar bears are among the largest carnivores in the world, rivaled only by the Kodiak brown bears of southern Alaska. As its scientific name, Ursusmaritimus, suggests, the polar bear is primarily a marine bear.

Numerous adaptations uniquely suit them to life in icy habitats. Their fur is thicker than any other bears’ and covers even their feet, for warmth and traction on ice.

Polar bears can swim as far as 40 miles. The long neck and narrow skull of the polar bear probably aid in streamlining the animal in the water,and the front feet are large, flat and oarlike. A thick layer of blubber provides buoyancy and insulation.

Polar Bear Habitat and Diet

Highly dependent on pack ice in the arctic region, polar bears spend much of their time hundreds of miles from land. Polar bears travel great distances in search of prey, which consists mainly of ringed seals and bearded seals.

The most important habitats for polar bears are the edges of pack ice, where currents and wind interact with the ice, forming a continually melting and refreezing matrix of ice patches. These are the areas of greatest seal abundance and accessibility. Individual bears can travel thousands of miles per year following the seasonal advance and retreat of sea ice.

In one study, a single radio-collared animal ranged over an area encompassing most of the north coast of Alaska—nearly 200,000 square miles. Polar bears can also swim as far as 40 miles.

Polar Bear Population in Decline

The World Conservation Union (IUCN) estimates that there are between 20,000 and 25,000 polar bears in the world, distributed throughout the Arctic region in 19 subpopulations of 100 to 3,000 bears each. Many of these populations are difficult to track accurately, but the trends in well-studied populations are alarming. In the western Hudson Bay, numbers have declined from 1,200 bears in 1987 to 935 bears in 2004. And in the Beaufort Sea north of Alaska, the population dropped 15 percent in five years, from 1,800 to 1,526 bears.

Only the populations of the islands of Canada’s Nunavut territory are stable or increasing. In May 2006, the IUCN added the polar bear to its Red List of the world’s most imperiled animals, predicting a 30 percent reduction in the polar bear population in the next 45 years.

Threats to Polar Bears

Climate Change/Global Warming: The most serious emerging threat to polar bears today is climate change. Polar bears face the loss of their sea-ice feeding and denning grounds as the Arctic climate rapidly warm.

Cover of Navigating the Arctic Meltdown: Polar BearNavigating the Arctic Meltdown: Polar Bears

This publication is part of a 10 part series called, Navigating the Arctic Meltdown (2007). This solution-based series focuses on the effects of global warming on arctic wildlife and on what can be done to help them through a 100-year bottleneck.

Pollution: Prevailing winds and water currents deposit residues of PCBs, pesticides and other persistent toxins in the Arctic region. Pollutants are stored in the animals’ fat and accumulate,so top predators such as polar bears receive doses sufficient to interfere with reproduction, growth and development, and immune function.

Tourism: Tourism can lead to bear kills,particularly where poor handling of food and garbage invites bears to get used to human presence and the access to food.

Oil Exploration: Oil exploration in prime polar bear habitats could cause pregnant females to avoid potential den sites, and spills pose a danger to bears and their prey.