Polar bears are among the largest bears in the world. Adult males may reach 800 kilograms (kg) or 1760 pounds (lbs). In Ontario, the largest male bear recorded from “live capture” research studies weighed 654 kg (1439 lbs). The average weight of male polar bears in Ontario is about 500 kg (1100 lbs). Adult female bears are smaller and average around 300 kg (660 lbs); their peak weights do not usually exceed 400 kg (880 lbs).
Polar bears are the most predatory of all bears. They spend most of the year hunting seals on sea ice. Ringed seals are their primary prey. Bearded seals are also an important food source. It was once believed that polar bears wandered throughout the Arctic and were carried around on moving sea ice. However, radio-telemetry (a technique where collars with a transmitting device are placed around a bear’s neck to allow researchers to locate and track the bear’s movements), and genetic techniques have shown polar bears often use the same areas each year.
Polar bears move greater distances and use larger areas (Figure 3) than other land mammals. Each year, they travel thousands of kilometres and use areas up to 300,000 square kilometres in size (an area about half the size of Saskatchewan or 42 times larger than the Greater Toronto Area).
Figure 3. Map showing movements of four female polar bears, as monitored by radio-telemetry from September 2007 until June 2008. Note the long distances travelled.
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