How do bears spend the winter?

Bears hibernate for the winter. Bears choose suitable caves when hibernating, usually in sunny sheltered hillsides or dead tree caves. The time of hibernation can last for 4 to 5 months. If it is disturbed during hibernation, it will wake up immediately and occasionally come out of the hole.

Bears are paralyzed during hibernation, but their body temperature does not decrease or drop slightly, sleep without eating for a long time, and is easy to wake up, and can respond immediately to external stimuli. It is called semi-hibernating animal.

Lack of food is the main cause of animal hibernation. If there is enough food, many bears will not hibernate, but will hunt all winter. But when there is not much food, the bear will hide in the hole for the winter. Small mammals will have a sharp drop in body temperature during hibernation, but the bear's body temperature will only drop by about 4 degrees, but the heart rate will slow down by 75%. Once the bear begins to hibernate, its energy source changes from diet to fat stored in the body.

Tom Evans, a field biologist who works for the U.S. Fish and Wildlife Service Polar Bear Program in Alaska, says the chemical process has changed dramatically. When fat burns, metabolism produces toxins. But when bears hibernate, cells break down these poisons into harmless substances and recycle them. This biochemical effect also allows bears to recover water from their bodies, so they do not urinate while hibernating, and polar bears can also take advantage of fat-burning mechanisms. This awakening hibernation allows polar bears to stay active throughout the winter without hiding in the hole.