Polar bears aren't deep hibernators, but enter a state of carnivore lethargy. Though hibernating females sleep soundly, they're easily and quickly aroused. Unlike most other hibernators, female polar bears give birth while hibernating. Scientists use radio collars to track the movements of polar bears. Once a polar bear is fitted with a radio collar, the collar sends signals to a receiving station via satellite.
Scientists can enter the data into a computer program that plots the polar bear's path.
Only female polar bears can be tracked using radio collars. Male polar bears have necks wider than their heads, and the collars simply fall off. The movements of polar bears can also be studied by following their tracks in the snow, usually by aircraft. Other behaviors are recorded by observing polar bears directly, or finding evidence of polar bears, such as a partially eaten seal. Most polar bear research is conducted in the spring or summer when weather conditions are more favorable to humans.