Why do some animals hibernate in the winter?

Grizzly black bears, hummingbirds and squirrels hibernate in the winter because a long, chilly season of little food and warmth is no picnic for these animals.

Unlike the warm seasons of spring and summer that provide an unlimited amount of food for these critters, the winter season only provides a cold, frozen ground where food is extremely scarce.

In addition, the winter days are frigid and short while the hours in the dark night seem to drag on for a chilly eternity. Searching for grub often leaves the stomachs of these animals empty because by the end of their search their bodies end up burning more calories than the animals get back from the food when and if any is found. So instead of starving or freezing to death, these animals decide to pack in all in for the long haul and hibernate during the winter months.

Hibernation helps these animals survive in the roughest and toughest conditions. By hibernating, an animal decreases its body's energy needs to a bare minimum. Hibernation is a process of lowering an animal's body temperature and slowing down its heartbeat into order to conserve energy during times of scarcity and stress.

Every animal hibernates in different ways. While squirrels can wake up every four days to grab a bite to eat and take a trip to the bathroom, black bears can stay dormant, or inactive, for up to seven months with no food, water, or visits to the bathroom.