The long winter nap is a famous bear habit. Although most wild bears that live in cold northern lands sleep a great deal during the winter, they do not really hibernate.
Bears do not sleep soundly the whole time, as do the woodchuck and other true hibernators.
A loud noise can easily awaken a sleeping bear. The bear may even wake up and come out of its den on mild winter days.
A bear prepares for its winter sleep by eating so much food that it gets fat. The fat helps nourish the bear’s body while it sleeps.
With the arrival of cold weather the bear stops eating and looks for a cave, a brush pile or a hollow in the base of a tree to use as a den. The den protects the bear from the weather.
When spring comes, the bear is awakened by the change in temperature and by hunger.
Animals that sleep through the winter do so to reduce their need for food during the cold lean winter months. – Dick Rogers