The polar bear's life cycle is closely tied to sea ice. Polar bears rely on the ice to travel, hunt seals, breed, and in some cases, den. Scientists believe polar bears are unlikely to survive if ice-free periods exceed their fasting ability (220 days), especially in areas that lack alternate marine mammal prey.
Polar bears are strong swimmers and divers, a characteristic that allows them to swim from one ice floe to the next. But there’s a limit to how far they can swim. Long swims are especially dangerous to young cubs.
Arctic weather can be fiercely cold. As humans, we need protective clothing and/or shelter to stay warm. Polar bears don’t. Their bodies thrive in the stark temperatures.
Built For the North
In the High Arctic, the sun sets in October and doesn't rise again until late February. Winter temperatures can plunge to -40° or -46 C (-50 F) and stay that way for days or weeks. The average January and February temperature is -34 C (-29 F).
Bears are insulated with two layers of fur and a thick layer of body fat. This provides enough insulation that their body temperature and metabolic rate doesn’t change, even when temperatures reach -37 C (-34 F).
To learn more about how polar bear’s bodies adjust to their climate, see physical characteristics. A polar bear's body temperature, 37 C (98.6 F), is average for mammals.
On bitterly cold days with fierce winds, polar bears dig shelter pits in snow banks and curl up in a tight ball. Sometimes they cover their muzzles—which radiate heat—with their thickly furred paws and let the snow drift around and over them.
Polar bears have more problems with overheating than they do with cold. That's why they typically walk at a leisurely pace. They can quickly overheat when they run.
Sharing The Arctic
Polar Bear FAQ
Are polar bears endangered?
Polar bears are listed under a variety of classifications depending on international, national, and regional regulations. Internationally, they are listed as a vulnerable species by the IUCN. In Russia, polar bears are classified as a Red Data Book species, a listing that includes animals considered rare or endangered. In the U.S., polar bears are listed as a threatened species under the Endangered Species Act. Canada considers polar bears a species of special concern under the National Species at Risk Act. On a regional level in Canada, polar bears are listed as threatened in both Manitoba and Ontario under provincial endangered species legislation.
In all cases, the primary conservation concern for polar bears is habitat loss and reduced access to their seal prey due to climate change. Scientists predict that as the Arctic continues to warm, two-thirds of the world's polar bears could disappear within this century. Research also shows that hope remains if action is taken to greatly reduce greenhouse gas emissions soon.
While rapid loss of sea ice is the primary threat to the polar bear’s long-term survival, other challenges include pollution, increased commercial use of the Arctic, overharvest, disease, and inadequate habitat protection (denning and seasonal resting areas).
At the 2014 meeting of the PBSG, the world's leading polar bear scientists reported that of the 19 subpopulations of polar bears, three were declining, six were stable, and one was increasing. They lacked sufficient data on the status of the remaining nine.
How many polar bears are there?
Scientists can only provide informed estimates. The latest IUCN report estimates there are approximately 26,000 of them.
How big are polar bears?
Very big! Adult males normally weigh 350 to more than 600 kilograms (775 to more than 1,300 pounds). Adult females are smaller, normally weighing 150 to 295 kilograms (330 to 650 pounds). Researchers in Canada estimated one male bear at 800 kilograms (1,700 pounds)!
Scientists usually refer to how tall bears are by measuring them at the shoulder when on all fours. Those heights are typically 1-1.5 meters (3.3-5 feet) for adult polar bears. An adult male may reach over three meters (10 feet) when standing on its hind legs.