Hibernation is different from sleep. With normal sleep, the animal moves a little, has an active brain, and can wake up very quickly.

There are different kinds of hibernation. A "True" hibernator appears to be dead because the animal's heart rate slows down and the body temperature drops to almost the same temperature as the outside The animal's breathing also slows down. It takes a long time for the animal to wake up and to move about. Some animals (like bears) are not true hibernators.

In the late summer and fall, before going into hibernation, animals eat alot of food. Their bodies are able to live off the stored body fat. They look for a safe place to spend the winter. (caves, dens, burrows)

Some hibernating animals wake up and move around, have a snack and then go back into hibernation again.

NOTE: "Torpor" is a shortened sleep time. The heart rate slows down and body temperature goes down, but the animal is able to wake up and move around.



In spring, ground squirrels come out of their dens in April and May. The young are born about a month later, coming out of the burrows (holes dug in the ground) in early June.

Near the end of June, adult males go back into hibernation. Adult females do the same in July. But the young are active all summer. In September when there is less food to be found they go into hibernation.

SHELTER - They dig a burrow with many tunnels, openings, and different rooms ( called chambers ). If a predator ( enemy ) comes in one hole, they can escape out another hole.

FOOD - The Richardson's Ground Squirrels store some food During hibernation, they wake up every 10 to 14 days and have a snack.



Some BATS are hibernators. In the fall large flocks of Big Brown Bats find shelter for the winter. The bats hang upside down and pull their wings and tails close to their bodies to keep warm. Their body temperature drops and they seem to be dead. Bats hibernate from October to April, waking up once a month. Bats likes warm buildings to hibernate in and are able squeeze through a hole the size of a thumb.


FROGS hibernate at the bottom of streams and ponds where the water does not freeze. Woodland frogs find shelter under leaves and dirt. During the winter they freeze but thaw out and wake up in the spring.


SNAKES travel to one spot where hundreds of them can hibernate together so they can stay warm. Snake dens can be found in rocks, burrows, or old wells and basements.


LADYBUGS spend the winter in a type of hibernation called "diapause". They fatten up for the winter by eating plenty of aphids and pollen. Then they hide in buildings, or under logs, rocks or piles of leaves.


BEARS are not "true" hibernators. They go into their dens ( caves, hollow trees, river banks ) in the fall Their body temperature drops alittle and their heart rate slows down, but not as much as true hibernators. Bears go into a "torpor" or temporary sleeep and can wake up and walk around. The tiny cubs are born in the dens during the winter season. Bears eat and eat in the late summer and fall, so that they can store fat before going to their dens. When they come out in the spring, bears are very thin and very hungry. Female polar bears will spend the winter in dens if they are going to give birth.

There are other animals that are not "true" hibernators. They take "naps" during the winter and wake up often.

ANIMALS THAT SLEEP AND EAT during the winter


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(updated May 2007)