A polar bear's home range can be enormous, far greater than that of any other species of bear. One Alaskan polar bear's home range was found to be 45 times the size of Great Smoky Mountains National Park, which supports some 400 black bears. A polar bear's home range can be 300 times the size of a brown bear's.
The size of a polar bear's range depends on a number of factors, including habitat quality and how much food is available there. Polar bears in food-rich areas have smaller home ranges, which often overlap those of other bears. Polar bears do not seem to have territories like other large carnivores, which makes sense as their habitat is always moving and seasonally changing.
• Populations occur in areas where many home ranges overlap. Governments have designated 19 populations of polar bears in the circumpolar region. These currently function as distinct management units. Scientists have recently discovered that there may be four distinct groupings of polar bears based on four different sea ice regions in the Arctic.
Polar bears respond to seasonal changes in the distribution of seals and sea ice. Cubs learn about these patterns during the time they spend with their mother. Young polar bears may travel more than 600 miles (1,000 kilometers) to set up a home range apart from their mother's, although subadult dispersal remains a little-studied topic for polar bears because tagging and tracking a quickly growing animal is tricky.
• Scientists believe that most bears limit travel to home ranges of a few hundred miles. But they know one satellite-tracked female trekked 3,000 miles (4,800 Km)—from Alaska's Prudhoe Bay to Greenland to Canada's Ellesmere Island and back to Greenland.