Polar bear the fourhorn sculpin. With the exception of pregnant females, polar bears are active year-round, although they have a vestigial hibernation induction trigger in their blood. Unlike brown and black bears, polar bears are capable of fasting for up to several months during late summer and early fall, when they cannot hunt for seals because the sea is unfrozen. When sea ice is unavailable during summer and early autumn, some populations live off fat reserves for months at a time, as polar bears do not 'hibernate' any time of the year. Being both curious animals and scavengers, polar bears investigate and
Polar bear bear is among the most sexually dimorphic of mammals, surpassed only by the pinnipeds such as elephant seals. The largest polar bear on record, reportedly weighing , was a male shot at Kotzebue Sound in northwestern Alaska in 1960. This specimen, when mounted, stood tall on its hindlegs. The shoulder height of an adult polar bear is . While all bears are short-tailed, the polar bear's tail is relatively the shortest amongst living bears, ranging from in length. Compared with its closest relative, the brown bear, the polar bear has a more elongated body build and a longer skull and