Polar Bear

Overview

The polar bear (Ursus maritimus) is a massive carnivorous mammal that inhabits the circumpolar Arctic region. It is uniquely adapted to the extreme cold and marine environment, with a thick layer of blubber, dense water-repellent fur, and large paws that act as snowshoes and swimming paddles. Polar bears are marine mammals that spend much of their lives on sea ice, which they use as a platform for hunting their primary prey, ringed and bearded seals. Adult male polar bears are among the largest bears in the world, rivaling the Kodiak bear in size. Their white to yellowish fur provides camouflage against the snow and ice, though their skin underneath is black to absorb heat. Polar bears have an exceptionally keen sense of smell, capable of detecting seals beneath several feet of snow and ice from great distances. They are powerful swimmers, with documented swims of over 400 kilometers in search of ice. Polar bears face significant threats from climate change, as the reduction in Arctic sea ice limits their hunting grounds and access to prey. The species is considered a sentinel of climate change impacts on Arctic ecosystems. Loss of sea ice forces bears to spend more time on land, where food sources are limited, leading to declining body condition, reduced reproductive success, and increased human-bear conflicts in Arctic communities.

How to identify

Large white to cream-colored bear with a relatively long neck and narrow head compared to other bear species. Adult males weigh 350-700 kg and measure 2.4-3 meters in length, while females are roughly half the size at 150-350 kg. The fur appears white but is actually translucent and hollow. The body is stocky with large paws measuring up to 30 cm across, equipped with non-retractable claws and bumpy footpads for traction on ice. Black skin is visible on the nose, lips, and footpads. No vocalizations are distinctive at distance, though they can produce chuffs, growls, and roars.

Habitat

Sea ice and adjacent coastal areas of the Arctic Ocean and surrounding seas. Polar bears depend on sea ice as a platform for hunting, traveling, and sometimes denning. They are found on annual sea ice over the continental shelf and inter-island archipelagos where biological productivity is highest. Pregnant females dig maternity dens in snowdrifts on land or on sea ice.

Distribution

Circumpolar Arctic distribution across five nations: Canada, Greenland (Denmark), Norway (Svalbard), Russia, and the United States (Alaska). The species occurs in 19 recognized subpopulations ranging from the Beaufort Sea to the Chukchi Sea, Bering Sea, Canadian Arctic Archipelago, Hudson Bay, Baffin Bay, Davis Strait, Barents Sea, Kara Sea, and East Greenland. The southernmost populations are found in James Bay, Canada.

Diet

Primarily carnivorous, specializing in hunting ringed seals (Pusa hispida) and bearded seals (Erignathus barbatus). Polar bears hunt seals by waiting at breathing holes in the ice or by stalking seals resting on the surface. They primarily consume the energy-rich blubber and skin. When seals are unavailable, they may prey on walrus calves, beluga whales, narwhals, seabirds, eggs, fish, and carrion including whale carcasses. During ice-free periods on land, they may consume vegetation, berries, and kelp, though these provide minimal nutritional value.

Behavior

Largely solitary except for mothers with cubs and breeding pairs. Polar bears are most active in hunting during the spring when seal pups are abundant. They are capable swimmers and can maintain speeds of 10 km/h in water. During summer when sea ice retreats, some populations remain on the ice while others come ashore and enter a state of walking hibernation with reduced metabolic rates. Polar bears do not defend territories but have large home ranges that can exceed 300,000 square kilometers. Males may engage in ritualized fighting during the breeding season. They are generally silent but curious animals.

Reproduction & life cycle

Breeding occurs from March to June, with peak mating in April and May. Females experience delayed implantation, with fertilized eggs not implanting until September or October. Pregnant females enter maternity dens in October-November, typically in coastal areas with sufficient snow accumulation. After a gestation period of about 195-265 days total (including delayed implantation), 1-3 cubs (usually 2) are born between November and January. Cubs weigh only 600-700 grams at birth and are blind and covered with fine fur. They emerge from dens in March-April and remain with their mother for approximately 2.5 years. Females typically breed every three years. Sexual maturity is reached at 4-5 years for females and 6 years for males.

When to look

Best observed from March to May during the seal hunting season when bears are most active on sea ice. In some regions like Churchill, Manitoba, bears gather along the coast in October-November waiting for sea ice to form. Cubs emerge from dens in March-April. Summer months see reduced activity and some populations move to land.

Cultural significance

Polar bears hold profound cultural significance for Indigenous Arctic peoples including the Inuit, Yupik, and Chukchi, featuring prominently in mythology, art, and traditional hunting practices. The bear is respected as a powerful spirit and has been sustainably hunted for subsistence for thousands of years, providing meat, hides, and other materials. Polar bears have become a global symbol of climate change and wilderness conservation. They appear on the coat of arms of Greenland and are protected under international agreements including the 1973 International Agreement on the Conservation of Polar Bears.

Similar species

• Kodiak Bear (Ursus arctos middendorffi)
• Grizzly Bear (Ursus arctos horribilis)
• Polar bear × Grizzly bear hybrid (Grolar/Pizzly bear)

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