Polar bears were once thought to be aimless wanderers, but scientists now believe that, like other members of the bear family, many of them have distinct territories, or home ranges.

After leaving their mothers, young polar bears may travel more than 1,000 kilometers / 600 miles to establish their own territory.

It appears that the size of a polar bear's range is determined by the amount of available food. Bears living in areas with an abundance of ice and seals have smaller home ranges.

A satellite-tracked polar bear surprised researchers with a 3,000 mile / 4,800 km trek. Starting at Prudhoe Bay in Alaska, she traveled across the top of the world to Greenland (See red line on map). She spent the winter there before moving on to Canada's Ellesmere Island and then back to Greenland again. (There must've been slim pickin's in that range.)

Wrangel Island is well known for its large concentrations of polar bears, and it has therefore become a key location for research. Keeping track of the bears' whereabouts is very important because of the threats they face, including climate change, pollution, and poaching.