11 Amazing Hibernation Facts for Kids
On a snowy morning, you and your kid can pull a warm blanket up to your chin and grab a snack from the kitchen. Outside your window, the trees are bare, the pond is icy, and the frogs, bats, and ground squirrels have completely vanished.
Your kid might point at the quiet backyard and ask how wild animals survive all winter when there is nothing left to eat. Many animals solve this problem by hitting pause on their bodies until warm spring weather brings their food back.
11 Interesting & Fun Hibernation Facts for Kids They Will Love to Know about
Hibernation is not just a normal bedtime nap. When animals hibernate, their hearts beat super slowly, their breathing almost stops, and their bodies cool way down to save energy.
Some animals even freeze like solid ice cubes or sleep for half the year without taking a single bathroom break. Not every animal hibernates, though: an arctic fox stays wide awake all winter, kept warm by its thick, fluffy coat.
Now let us take a look at those fun hibernation facts!
1. Bears Are Special Hibernators Who Can Wake Up Fast
Cartoon shows and storybooks almost always show a big bear snoring away in a deep sleep all winter long. That popular picture is only half right.
For a long time, scientists said bears were not true hibernators because their body temperature drops only a few degrees instead of plunging way down near freezing. Today, most scientists agree that bears really do hibernate: a black bear’s heart can slow to around 10 beats per minute, and its body uses only about one-quarter of its normal energy.
Because a bear keeps its big body warm inside its cozy den, it can wake up fast to protect itself or its babies if danger comes close. Big polar bears are different: usually only moms-to-be dig snowy winter dens, while the rest keep hunting out on the sea ice.
2. Arctic Ground Squirrels Cool Their Bodies Below Freezing
True hibernators let their bodies get super cold to save energy while they sleep through the winter. The Arctic ground squirrel holds the record among mammals for the coldest body temperature during hibernation.
During the summer, this squirrel has a warm body temperature of 99 degrees Fahrenheit, which is almost the exact same as yours. When it hibernates for 7 to 8 months (up to 250 days), its body temperature drops down to 27 degrees Fahrenheit.
That is a few degrees colder than the temperature where water turns to ice, yet its blood stays liquid through a trick called supercooling. Every two to three weeks, the squirrel shivers to warm itself back up and stays awake for about 12 to 15 hours before going right back to sleep.
3. Wood Frogs Freeze Solid Like Ice and Wake Up in Spring
For almost every animal on Earth, freezing into solid ice is deadly because sharp ice crystals tear apart the tiny cells inside the body. The little wood frog breaks that rule every single winter.
When winter arrives in the northern woods, the wood frog packs its cells with a natural blood sugar called glucose that works like liquid antifreeze. Up to two-thirds of the water in its body turns to ice, so the frog feels like an icy stone, and it has zero heartbeat and zero breathing. In chilly Alaska, wood frogs can stay frozen for up to seven months.
When warm spring sunshine turns the snow into mud, the frog thaws from the inside out. Its heart starts beating first, its brain wakes up next, and soon it hops off to a pond completely unharmed.
4. Black Bears Sleep for Months Without Eating, Drinking, or Peeing
When you sleep at night, you wake up hungry for breakfast and ready to use the bathroom. Hibernating black bears do something that sounds almost impossible.
A black bear can stay inside its winter den for more than 100 days, and sometimes five to seven months, without eating food, drinking water, or going to the bathroom. All the bear needs inside its den is fresh air to breathe while it lives off a thick layer of stored body fat that can be four to five inches deep.
Instead of peeing, the bear’s body recycles its own waste and turns that pee back into protein. That recycled protein keeps the bear’s muscles and bones strong even though it lies still for months.
5. Bears Eat Almost Nonstop Before Winter Bedtime
Staying asleep for half a year without a single snack takes a huge tank of stored fuel. That is why bears spend late summer and autumn eating almost nonstop.
Black bears munch on nuts, berries, fruits, insects, and honey to pack on a thick layer of extra fat before winter starts. Most adult male black bears weigh 180 to 250 pounds, and the biggest wild black bear ever found weighed about 880 pounds.
That record bear weighed about as much as five grown-ups put together! By the time spring arrives, a sleeping bear can lose up to one-third of its body weight just resting in its den.
6. Mother Black Bears Give Birth to Tiny Cubs While Dormant
Winter sounds like the worst time of year to have babies, but mother black bears welcome their newborns right in the middle of their winter rest. The cubs are born inside the cozy den in January or February while their mom is dormant.
Even though an adult mother bear weighs well over 100 pounds, a newborn black bear cub weighs only 8 to 12 ounces (less than 1 pound). That means a brand-new baby bear weighs about as much as a single can of soup in your kitchen cupboard!
The tiny cubs are born blind and almost hairless, with only very thin, fine fur, so they snuggle deep into their mother’s warm fur and drink her rich milk all winter. By the time they walk out of the den in April or May, those cubs have grown to about 4 to 10 pounds, which is about as heavy as a pet cat.
7. The Common Poorwill Is the Only Bird Known to Hibernate
When winter gets cold and bugs disappear, most birds either fly south to warmer places or puff up their feathers and hunt for seeds. Only one bird in the whole world is known to hibernate, and it is called the common poorwill.
This little brown-and-gray bird lives in western North America and measures only about 8 inches long, making it a little smaller than a backyard robin. When night-flying insects vanish in winter, the poorwill hides among rocks and drops its body temperature and energy use for days or weeks at a time.
Long before modern scientists studied this bird in the 1940s, the Hopi people already knew its secret. Their name for the common poorwill is Hölchko, which means “the sleeping one”.
8. Hibernating Bats Slow Their Racing Hearts to a Crawl
Flying takes a lot of energy, so a tiny bat’s heart normally races like a little drum when it chases bugs at night. Once winter freezes the bugs away, many bats tuck themselves into quiet caves, hollow trees, or old mines to hibernate.
To make their tiny fat supply last all winter, bats drop their heart rate from hundreds of beats per minute all the way down to about 25 beats per minute. Their breathing and body temperature plunge too, so they barely use any energy while hanging upside down.
Because bats are so small, waking up even once in the middle of winter burns up precious fat. That is why many bat caves close to visitors in winter, so the sleeping bats do not wake up early and go hungry. Bats also face a disease called white-nose syndrome, which makes them wake up too often during hibernation and burn through their fat.
9. Snakes Share Giant Group Bedrooms Called Hibernacula
Cold-blooded reptiles like snakes cannot warm their own blood the way mammals do, so they have their own special version of winter sleep called brumation. Brumation starts in late autumn when the weather turns chilly and daylight hours get shorter.
Instead of curling up alone, snakes like black rat snakes often crawl into the exact same underground den to spend the winter together in a big group. Scientists call this shared winter bedroom a hibernaculum.
While inside their hibernaculum, snakes stop eating food completely for the entire winter. However, unlike bears, brumating snakes still wake up just enough on milder winter days to crawl out and take a drink of water.
10. Animals in Hot Deserts and Tropical Forests Hibernate Too
You probably picture deep snowdrifts and icy winds whenever you think about hibernation. Surprisingly, animals in warm and sunny places use a similar slow-down trick when food or water runs out.
On the warm tropical island of Madagascar, tiny dwarf lemurs were the first primates ever found to hibernate, snoozing in tree holes or underground for up to seven months. Even in warm Florida, some black bears head into dens for the winter (mostly moms getting ready to have cubs), while many others stay awake and keep searching for food.
In sizzling hot deserts, animals like the desert tortoise do a summer version of hibernation called estivation. They dig into cool underground burrows and slow their bodies down to escape extreme summer heat and drought.
11. Mourning Cloak Butterflies Make Their Own Antifreeze
Most people think all butterflies either die when winter comes or fly thousands of miles south like monarch butterflies. The mourning cloak butterfly stays right in the snowy woods all winter long as a full-grown adult.
When cold weather arrives, this butterfly tucks itself inside a cozy tree hole, under loose tree bark, or beneath fallen logs. Next, it lowers the amount of water inside its body and builds up a special liquid called glycerol.
Glycerol works just like the antifreeze liquid in your family car, keeping ice from forming inside the butterfly. Because it is already waiting in the woods as an adult, the mourning cloak is usually the very first butterfly you will spot fluttering around in early spring.
Frequently Asked Questions (FAQs)
Why do animals hibernate in the winter?
Animals hibernate to save energy and survive the winter months when cold weather makes food and water very hard to find.
Do bears really hibernate all winter?
Yes! Most scientists now agree that bears are true hibernators. Their body temperature drops only a few degrees, but their heart rate and energy use drop way down, and they can wake up quickly if danger comes near.
Which animal gets the coldest during hibernation?
The Arctic ground squirrel gets the coldest of any mammal, dropping its body temperature down to 27 degrees Fahrenheit, which is below freezing.
Can birds hibernate in the winter?
Yes, the common poorwill of western North America is the only bird known to hibernate, slowing its body down for days or weeks when insects disappear.
What is the difference between hibernation and brumation?
Hibernation is the deep winter slow-down of animals like ground squirrels, bats, and bears. Many scientists use the word brumation for the winter rest of cold-blooded reptiles like snakes and turtles, which stop eating but may wake on warmer days to drink water.
What is summer hibernation called?
When desert animals slow their bodies down to survive hot and dry summer weather, scientists call that sleep estivation.
Next time you and your kid walk past a quiet pond or a hollow tree in winter, you will know that amazing animals are tucked away right beneath your feet. From frozen wood frogs to tiny newborn bear cubs, winter nature is full of hidden surprises waiting for spring.
That was it, folks! Hope you and your little one enjoyed these amazing facts about hibernation.
