Slow, sleepy winter days find many animals curled up in their dens. They sleep warmly through winter, awakening in spring ready to enjoy the renewed Earth. This unusual, deep sleep is called hibernation.
What Is Hibernation?
True hibernation is a very deep sleep. The animal's body temperature drops, its breathing slows, and it is very difficult to awaken. But some animals, such as most bears, do not really hibernate.
Many animals are dormant in the cold weather. Being dormant means that they stop moving around, which saves them energy. Animals may go dormant because of something usual and natural such as winter weather. Wasps, snakes, turtles, and gila monsters are some animals that go dormant. Hibernation is one kind of dormancy.
These are some of the animals who hibernate or remain dormant (inactive) during the winter:
What's a Super Hibernator?
Even though bears do not have a lower body temperature during the winter, they are very good at staying in their dens, fast asleep without eating, drinking, or going to the bathroom for months at a time. Smaller animals whose body temperature does go low—such as the chipmunk—must wake up every so often to take care of these things.
Why Do They Hibernate?
In colder countries, winter is hard for animals. Everyone, including non-industrial humans, is short on food. Game animals such as deer, turkeys, squirrels, and rabbits do not hibernate. They are available to be hunted, and they must make do with what forage (food) they can find.
A natural way for animals to wait out these difficult times is hibernation. Going into snug dens in the earth, they eat very little or nothing, having fattened up during the fall months.
Do Humans Hibernate?
How many people do you see outside on a cold, cold night? How many people on a nice summer's night? Humans may not exactly hibernate, but we do have habits we have developed to cope with the cold. Holiday meals, heavy and sweet, give us lots of calories which was a very good thing in the old days when hard work for everyone was normal. Before travel by car was easy, relatives coming to stay for the holidays would usually be with you for at least a couple of weeks of feasting and mostly indoor fun. Our cold weather habits aren't quite hibernation, but both things do have a lot in common.
Get Ready for Groundhog Day!
Every year, America watches to see what happens when a certain hibernator will wake up from his winter's sleep. On February 2, all eyes will be on Punxsutawney Phil. Will he see his shadow or not? If he sees his shadow, legend says we will have six more weeks of winter! If he doesn't see his shadow, we will have an early Spring.
Facts about Groundhogs:
They are true hibernators. Their temperature drops, and their breathing slows down.
They eat mostly greens and fruits.
Baby groundhogs (called kits or cubs) are born in mid-April or May. If you'd like more books on these legendary weather wizards, check out our Groundhog Day booklist.
Hibernating in the Library
You can spend your winter dormancy with a good book. Here are some which teach about hibernation. Click on any title to learn more. CRRL library patrons may request books be held for them. Starred (*) titles are picture books—good for young children.
Animals Hibernating: How Animals Survive Extreme Conditions by Pamela Hickman
Learn how reptiles, birds, amphibians, and mammals hibernate. Includes several ideas for science activities.
Animals in Winter by Henrietta Bancroft and Richard G. Van Gelder
Best for early elementary or preschool children, this bright volume includes tips on how to feed active animals in the wintertime.
Animals That Hibernate by Larry Dane Brimner
Focus is on science here in a book that's good for mid- to upper elementary school reports. Includes an index.
Do Not Disturb: The Mysteries of Animal Hibernation and Sleep by Margery Facklam
Another good choice for mid- to upper elementary grades that discusses the differences in the three types of hibernation: deep sleep, light sleep, and daily dormancy.
*Every Autumn Comes the Bear by Jim Arnosky
A lovely picture book from the author of Crinkleroot nature guides tells about the days leading up to a bear's deep sleep.
*Sleep, Black Bear, Sleep by Jane Yolen and Heidi E. Y. Stemple
Gentle rhymes from a team of talented children's authors about imaginary hibernations. While not especially scientific, it's a good choice for just before nap time.
*Time to Sleep by Denise Fleming
Bear spreads the word to her hibernating friends that winter is coming, and it's time for sleep.
From the Web:
Hibernating Animal Print Outs
Gives an overview of hibernation with useful print outs for projects on creatures that hibernate.