Polar bears respond to seasonal changes and the distribution of seals and sea ice. In food-rich areas, they have smaller home ranges and their habitat often overlaps with other bears.
Polar bears in sea-ice regions with hard-to-reach prey travel farther and take longer to feed.
When a young polar bear grows up, it may travel more than 1,000 kilometers (621 miles) to set up a home range apart from its mother's, although subadult dispersal remains a scarcely studied topic, because tagging and tracking a quickly maturing animal is tricky.
Scientists believe that most polar bears limit travel to home ranges of a few hundred miles. However, they know of one satellite-tracked female that trekked 4,796 kiometers (2,980) miles—from Alaska's Prudhoe Bay to Greenland to Canada's Ellesmere Island and back to Greenland.
The Four Sea Ice Regions
Polar bears need a platform of sea ice to more easily reach their seal prey. But, not all sea ice is equal.
Some sea ice lies over productive hunting areas, and some ice regions will melt sooner than others in a warming Arctic.
Governments and scientists have designated 19 populations of polar bears based in four different sea-ice regions in the North Circumpolar Region (the Arctic).
These sea-ice regions function as distinct management units and are spread out among five countries: Canada, the United States (Alaska), Greenland, Russia, and Norway.
The following four sea-ice ecoregions differ in geography, status, sea ice levels, and vulnerability to climate change.
1. Seasonal Ice
Baffin Bay, Davis Strait, Foxe Basin, Southern Hudson Bay, and Western Hudson Bay
Seasonal ice areas occur at the southern extreme of the polar bear's range and include places like Canada's Hudson Bay, where the ice melts completely each summer and the bears must wait for freeze-up in the fall until they can hunt again.
Status of these populations: Polar bears in seasonal ice areas are the most endangered, with longer and longer ice-free seasons testing the limits of their fat reserves.
2. Polar Basin Divergent Ice
Barents Sea, Chukchi Sea, Kara Sea, Laptev Sea, and the Southern Beaufort Sea
In these areas, sea ice forms along the shore and then retreats, especially in summer. As the sea ice retreats farther and farther from shore in a warming Arctic, these polar bears are faced with a choice of coming ashore—and fasting until the ice returns in the fall—or swimming long, exhausting distances to reach the remaining pack ice.
However, because ice located far offshore lies over less productive waters, bears in these areas may successfully complete a marathon swim yet still not find any seals to hunt.
Status of these populations: Polar bears that live in these areas are at great risk—from longer and longer swims, prolonged fasting periods, and encounters with humans on shore.
3. Polar Basin Convergent Ice
Eastern Greenland, Northern Beaufort Sea, and the Queen Elizabeth Islands
Sea ice formed locally and transported from other parts of the Arctic collects along the shore of these habitats, providing polar bears with access to seals over productive waters.
Status of these populations: Polar bears in these areas are faring well now, but scientists predict that ice in these areas will disappear within 75 years—and, with it, resident polar bear populations—unless action is taken to reduce carbon emissions.
4. Archipelago Ice
Gulf of Boothia, Kane Basin, Lancaster Sound, M'Clintock Channel, Norwegian Bay, and the Viscount Melville Sound
Status of these populations: This ecoregion is likely to provide a last refuge for polar bears and their sea-ice prey, but ultimately it too is threatened, without action on climate change.
Why does it help to divide the Arctic into sea-ice regions?
It allows scientists to make informed estimates about how a population is faring, based on the health and condition of well-studied populations within the same region or across various regions.
It’s the best tool for making comparisons.
Well known for their slow, plodding gait, polar bears walk at about five to six kilometers (3.73 miles) per hour. Females with small cubs walk more slowly, about two-and-a-half to four kilometers (1.55 to 2.48 miles) per hour.
Polar bears are able to gallop as fast as a horse over short distances but prefer to amble leisurely.
Norwegian scientist Nils Oritsland showed us that polar bears expend more than twice the energy of most other mammals when walking or running, showing higher-than-average increases in temperature and in oxygen consumption.
Walking bears expend 13 times more energy than resting bears. This partly explains their preference for still-hunting, which usually involves a long, patient wait for a seal to surface at a breathing hole in the sea ice.
Polar bears are natural sprinters and can run as fast as 40 kilometers per hour—but only for short distances.
Younger, leaner bears are the best runners. They can cover two kilometers without stopping, whereas older, larger bears will quickly overheat.
Watch polar bears as they travel across the sea ice to hunt seals.
Polar Bear FAQ
We answer the most frequently asked polar bear questions.