How do animals survive in winter?

Part 3: Nap time

Henrietta and I already talked about how animals survive winter by migrating or adapting, but what else do they do?

Hibernation

Many animals stay active in winter, either by leaving or adapting, but some survive winter by hibernating. Hibernation is like a very deep sleep.

The black bear is a "champion" hibernator - it can sleep 100 days without eating or drinking. How's that for sleeping in? Bears prepare for hibernation by putting on a lot of fat in summer and fall. In winter, a bear stays in its den, rolled up in a tight ball to keep out the cold. Mother bears hibernate tightly curled up with their cubs. A hibernating bear lowers its body temperature and heart rate to conserve energy.

Checking in to the hibernation hotel

Chipmunks also hibernate, but instead of storing fat for the winter, they occasionally wake up to eat nuts and seeds from the reserves they built up in fall.

Frogs and turtles also hibernate. Aquatic frogs (that live in water), hibernate at the bottom of their pond, just on top of the mud or partly buried. Terrestrial (land) frogs hibernate in soil, or in cracks in logs or rocks. Hibernating turtles bury themselves in the mud. Both frogs and turtles slow down their metabolism (everything in their body slows down) so much that they stop breathing and their heart stops beating. Ice crystals even form in their bodies, and these frosty frogsicles and turtlesicles can appear to be dead! However special "antifreeze" proteins prevent their lungs, heart, and other organs from freezing, so they can successfully come back from the dead in spring!

Turtles preparing to hibernate

Many insects go into a sort of hibernation called "diapause" in winter. This is like putting their bodies on "pause" for the winter, and starting again in spring.

All this talk of hibernation is making me sleepy, since hedgehogs also hibernate in winter. We wake up once in a while though, so I'll still be able to update the blog!

How do animals survive in winter?

Part 2: Getting a winter makeover

Last time I visited Henrietta, we chatted about migration. Today I popped over to learn a bit more about a different way animals can survive winter.

Adaptation

Not all animals leave in winter - some adapt. This means they make changes that allow them to survive and stay active in the winter.

Some birds, such as the black-capped chickadee, stick around in winter. To stay warm, chickadees "fluff" themselves up. This traps more air between their feathers, and keeps them warm just like a down-filled blanket may keep you warm. At night, they drop their body temperature - this allows them to use less energy trying to stay warm (it's like turning down a thermostat!).

Chickadees fluffing themselves up for the winter

In winter, deer keep warm by growing special hollow hairs which trap air. They also grow a dense wool-like under-fur and store fat in fall to keep them warm. The fat gives them energy too, since food is harder to find in winter.

Squirrels also grow thicker fur to stay warm in winter. However, unlike deer, they don't search for food in winter. Instead, they feed on large reserves of nuts and seeds that they hid away in fall.

Beavers do the same thing - in fall, they gather branches and store them at the bottom of their pond. When the pond freezes, they don't leave the pond all winter - they bring their food reserves into their lodge (where they live).

Beavers spending winter in their lodge

Look around when you're outside - you may spot some more animals that stay active in winter! More winter survival strategies coming up next time...