Brrrr! It’s getting chilly in the northern part of our planet. When it’s cold out, people wear sweaters and scarves to stay warm. But what do animals do? 

Some animals hibernate. Their bodies slow down to save energy. This adaptation helps them survive the harshest months of the year. “It’s a way to avoid periods when there’s very little to eat,” says Mark Brigham, a biologist at the University of Regina in Canada. 

Hundreds of species hibernate—but each does it a little differently. Here are four animals that snooze through the winter in unusual ways. 

This colorful group of ladybugs is like a giant slumber party! To survive winters, thousands of the tiny beetles cluster together. 

Ladybugs usually live alone. But when temperatures drop, the insects release chemicals into the air. The substances signal other ladybugs to huddle together, says Laura Lavine. She’s a scientist at Washington State University who studies insects. The ladybugs form a pile and snooze until spring. Scientists aren’t sure why they snuggle together. One theory is that being in a large group helps protect individual beetles from being eaten by predators like birds. 

Ladybugs find their way inside cracks, under tree bark, and even inside homes. “They squeeze into the craziest places,” Lavine says.

Many hibernating animals lower their body temperature to save energy. But no mammal’s body cools as much as the arctic ground squirrel’s. Its body can reach -2.9°C (27°F). At that temperature, any other mammal would die, says Cory Williams, a biologist at the University of Alaska Fairbanks.

In the summer, the squirrels stuff themselves with leaves and berries, almost doubling their body weight. During hibernation, the animals don’t eat or drink. Instead, they rely on the extra fat they’ve stored to get the energy they need to survive. 

Arctic ground squirrels live in the northern-most parts of the U.S., Canada, and Siberia. They hibernate for up to nine months in their underground burrows! Can you imagine spending that long in bed?

Many birds migrate to warmer places during winter. There’s only one bird in the world that’s known to hibernate: the common poorwilll, which lives in western North America.

In the fall, the birds prepare for winter the way many animals do: They put on weight. As temperatures drop, the birds sit on the ground, cool their bodies, and slow their body functions. They stay still for up to 10 weeks.

Sitting out in the open could be risky for a bird. But the common poorwill’s coloring serves as camouflage, hiding it from predators like foxes, says Brigham. 

The birds look frozen, but they are alive. When they are ready to become active, the birds take 20 minutes to warm up and fly away. 

You may have noticed painted turtles basking in the sun on rocks or logs in your local pond. The reptiles live in water, but they breathe air through their lungs like humans do. So what happens if a layer of ice traps the turtles underwater?

During the winter, painted turtles hunker down at the bottom of the pond and start breathing through their butts! The thin skin in that area of their body can absorb oxygen that’s in the water. The turtles can hibernate like this for up to 100 days, says Jacqueline Litzgus, a biologist at Laurentian University in Canada. They don’t freeze because the water is slightly warmer at the bottom of the pond.

Painted turtle babies are different. If it’s cold when they hatch, they hibernate in nests on land. The babies’ body temperature can drop as low as -15°C (5°F)!