Polar Bear
The polar bear (Ursus maritimus), whose scientific name means sea bear, is the largest land carnivore on Earth and the top predator of the Arctic. Adult males usually weigh 350 to 700 kilograms and measure 2.4 to 2.6 meters, yet they move with surprising ease across sea ice and can swim for days in open water. Their skin is black beneath a coat of transparent, hollow hairs that scatter light and look white, and a layer of blubber up to 11 centimeters thick keeps them warm far below freezing. Polar bears live in Canada, Greenland, Norway's Svalbard, Russia and Alaska, and depend almost entirely on ringed and bearded seals, which they ambush at breathing holes or on the ice. Because they hunt from the sea ice, they are classified as marine mammals. As the climate warms, the ice forms later and breaks up earlier each year, cutting into the time bears have to hunt and build up the fat they need to survive. The IUCN lists the species as Vulnerable, with about 26,000 bears, in a range of 22,000 to 31,000, in 20 subpopulations.
Where do polar bears live?
Polar bears live around the Arctic Ocean in five countries: Canada, Greenland, Norway, through Svalbard, Russia and the United States, in Alaska. Canada has about two thirds of them. Scientists divide them into 20 subpopulations, from Hudson Bay, the southernmost, to the High Arctic islands and the coasts of Siberia. They are tied to the sea ice, spending most of their lives on the frozen ocean, which they use to hunt seals, rest and travel enormous distances, sometimes thousands of kilometers in a year. The richest areas are shallow waters over the continental shelf and the edges of polynyas, patches of open water in the ice where seals gather. Where the ice melts completely in summer, as in Hudson Bay, bears spend months on land living off their fat, and pregnant females dig dens in snowbanks on land to give birth. Polar bears do not live in Antarctica, so they never meet penguins. The best places to see them are Churchill in Manitoba in October and November, Svalbard on summer cruises, Kaktovik in Alaska in September and October, and Wrangel Island in Russia.
How big is a polar bear?
The polar bear is the largest bear and the largest land carnivore alive, matched only by the biggest Kodiak brown bears. Adult males usually measure 2.4 to 2.6 meters from nose to tail and weigh 350 to 700 kilograms, and standing on their hind legs they can be over 3 meters tall. Females are about half their size, at 1.8 to 2 meters and 150 to 300 kilograms, although a pregnant female can double her weight before entering the den. The heaviest polar bear on record was a male shot at Kotzebue Sound, Alaska, in 1960, said to weigh about 1,002 kilograms. Weight changes a lot through the year: bears are heaviest in late spring, after weeks of eating seal pups, and lightest at the end of a long summer on land, when they may have lost a third of their weight. The body is longer and slimmer than a brown bear's, with a long neck, a small head and small ears that lose little heat. Cubs, by contrast, are tiny: they are born in December or January weighing only about 600 grams, blind and almost hairless, and leave the den in spring at around 10 to 15 kilograms.
What do polar bears eat?
Seals form the core of the polar bear's diet, with ringed seals being by far the most important prey, followed by bearded seals. Bears are remarkably patient hunters. They practice a technique called still hunting, waiting motionless beside a seal's breathing hole in the ice for hours until the animal surfaces. They will also stalk seals resting on top of the ice, crawling forward slowly to close the distance before launching a short charge. A successful hunt can provide enough fat to sustain a bear for many days. When seals are scarce, polar bears may eat walrus, beluga whales, bird eggs, or even kelp, though none of these alternatives come close to replacing the energy gained from seal blubber.
Why are polar bears white? Adaptations to the cold
Few animals are as well equipped for extreme cold as the polar bear. Beneath its fur, the skin is black, which helps absorb heat from sunlight. The outer coat is made up of guard hairs that are transparent and hollow, scattering light so the bear appears white or yellowish against snow and ice. Below the skin lies a layer of blubber up to 11 centimeters thick that insulates the body and serves as an energy store during lean periods. Their large, slightly webbed paws make them capable swimmers over long distances, and rough pads on the soles give them grip on slippery ice. A strong sense of smell allows them to detect a seal beneath a meter of snow, making it one of their most valuable hunting tools.
Are polar bears dangerous?
Outside of mothers with cubs, polar bears lead largely solitary lives and roam vast territories across the ice. They are generally curious animals and will investigate unfamiliar objects or smells without much hesitation. That curiosity, combined with their size and strength, makes them genuinely dangerous to people. Unlike most bears, polar bears are active predators with no natural fear of humans, and a hungry bear in particular will approach settlements, camps, or people directly. Fatal attacks are rare but real: in 2023 a polar bear killed a woman and a young boy in the village of Wales, Alaska, and there have been deaths in Svalbard and northern Canada. Communities and research teams in polar bear territory typically carry flares and firearms as a precaution. Females give birth in snow dens, usually to twins, and are fiercely protective of their young during the first two years of a cub's life.
Why are polar bears endangered?
The IUCN classifies the polar bear as Vulnerable, one step below Endangered, with about 26,000 bears, in a range of 22,000 to 31,000, spread across 20 subpopulations. The threat is clear: polar bears need sea ice to hunt seals, and climate change is shrinking it. Arctic ice now forms later in autumn and breaks up earlier in spring, so bears have less time to hunt and must fast longer on land. In Western Hudson Bay, the best studied group, bears have become thinner, fewer cubs survive and numbers fell from 842 in 2016 to 618 in 2021. Some subpopulations are stable and others are poorly known, and in 2022 scientists found a small group in Southeast Greenland that survives by hunting from glacier ice, though few places have such glaciers. Studies published in 2020 projected that, if emissions keep rising, most subpopulations could collapse by 2100, while cutting emissions would keep many of them alive. Hunting is regulated under the 1973 agreement among the five range countries, the United States listed the bear as Threatened in 2008, and oil and gas activity, shipping and pollution add further pressure.
Where it is found
The Polar Bear can be found in places such as:
