Bears are said to hibernate during the winter, particularly during the extremely cold weather in the northern parts of their range. But there is a lot of confusion among people whether bears really hibernate.
So, do bears hibernate? Strictly speaking, the winter sleep of bears is not true hibernation. Their temperatures and breathing remain relatively normal, and during warm spells, some bears may emerge and remain outside for a day or so before returning to their sleeping quarters. Hibernation means sleeping for the whole winter, hence bears are not true hibernators.
Bears are much more easily disturbed during their winter sleep than is commonly thought and may scare the wits out of a trustful human being who approaches too closely.
If the investigator is persistent, he may be severely injured by the outraged bear whose sleep he has disturbed.
The cubs are born during this winter sleep. If one considers the size of the parents, they are very poor excuses for offspring, being smaller than the young of a porcupine and sometimes weighing no more than 6 or 8 ounces at birth.
Although polar bears are exposed to far worse weather conditions than other bears, only pregnant females sleep during the winter. They dig a hole in the ice and snow and remain there for several months, during which time the young are born and develop sufficiently to be taken outside.