This is Kenai who lives at the Minnesota Zoo with two other Grizzlies. He is a brown bear which are often referred to as Grizzlies in America. They technically do not hibernate. They do sleep through most of the winter season, but they are able to be awakened. Grizzly bears and black bears generally do not eat, drink, or have external bodily functions during hibernation. Bears live off of a layer of fat which was built-up during summer and autumn. Bears maintain a body temperature close to normal during hibernation which lets them react to danger and sources of food faster than many other hibernating animals. Bears at the Minnesota Zoo are fed during the winter season. In preparation for the winter when they will be sleeping and not eating, brown bears put on weight in order to survive. Particularly in the far north, brown bears add up to 400 pounds of fat every summer! A large female brown bear can get up to 770 pounds and a large male can weigh 1,300 pounds before winter. Between the months of January and March, up to four hairless cubs are born while the mother brown bear is sleeping.