You might think all squirrels vanish in winter, but honestly, that’s not quite true. Some ground squirrels actually hibernate for months, while most tree squirrels stay semi-active, taking short naps and living off their food stashes.
Some squirrels sleep deeply, others just take quick snoozes during cold snaps, and their choices really depend on where they live and how they behave. If you’re curious, you’ll start to notice the difference between a hibernating squirrel and one that’s just less active, and you’ll get a sense of how these little guys manage to survive the cold.
Why Do Some Squirrels Hibernate In Winter
Some squirrels get through winter by slowing down, burning fat, and hiding out in cozy burrows or nests. You’ll find out which species really hibernate, how their bodies change, and why that helps them make it through those long, cold months.
Hibernation Explained
Hibernation isn’t just a nap—it’s a long, deep sleep that slashes energy use. Unlike a quick rest, true hibernation can last weeks or months, letting animals survive when food’s gone and it’s freezing outside.
A hibernating squirrel’s body temperature can drop almost to freezing. Its heart slows from hundreds of beats a minute to just a few. The metabolism nearly stops, so the squirrel burns fat slowly and doesn’t need to look for food.
You’ll usually see hibernation in places with brutal winters. Where snow piles up and the cold drags on, ground squirrels dig burrows that stay warmer than the surface. These burrows also keep out predators and harsh weather, so the squirrel can sleep straight through to spring.
Which Squirrel Species Hibernate
Not all squirrels hibernate, and that’s kind of fascinating. Ground squirrels, like the thirteen-lined ground squirrel and the Arctic ground squirrel, go into true hibernation. Tree squirrels—think Eastern gray or fox squirrels—don’t. Flying squirrels slow down in winter, but they don’t hibernate fully either.
The thirteen-lined ground squirrel spends months in its burrow, hibernating. Arctic ground squirrels take it even further, with body temperatures that nearly hit freezing. These guys live in cold, open places where winter wipes out their food.
If you spot a squirrel in a tree or your yard in winter, it’s probably a non-hibernator. Those squirrels count on hidden food, leafy nests (dreys), or short spells of torpor instead of sleeping the whole season away.
Physiological Changes During Hibernation
Hibernating squirrels go through some wild body changes. Their body temperature can plunge from about 37°C (99°F) to almost 0–2°C, especially in Arctic ground squirrels. That huge drop helps them save energy and keep warm.
Their heart rate and breathing slow way down. A heart that normally beats 200–300 times a minute can drop to under 10 beats during deep hibernation. Breathing gets shallow, matching the slow metabolism.
The brain and organs shift gears to protect cells. Hibernating squirrels ramp up certain proteins and change blood flow, so their tissues don’t get damaged from the cold. They depend on white and brown fat for energy, which keeps them going and even helps warm them up during brief wake-ups.
If you want to dig deeper into how ground squirrels use their burrows and extreme body cooling, check out research on the arctic ground squirrel.
How Squirrels Survive Winter Without Hibernating
Some squirrels stay active all winter by using shelters, eating stored food, and relying on body fat for warmth. You’ll see them make fewer trips outside, dig up cached nuts, and hunker down in nests when it’s bitter cold.
Tree Squirrels and Their Winter Strategies
Gray squirrels and fox squirrels don’t hibernate—they’re out and about all winter. You might spot them foraging on milder days or digging up nuts under the snow. They don’t waste energy: their trips are shorter, and they spend more time hiding from predators.
Gray squirrels use memory and scent to find their hidden stashes, which is honestly pretty impressive. Fox squirrels make bigger caches and sometimes go for visible food like tree buds. Both types grow thicker fur in fall, trapping air and slowing heat loss.
When it’s really cold, they move less and slow down. Sometimes you’ll hear them calling or see one perched in the sun, soaking up warmth before heading out again.
Importance of Dreys and Nests
Dreys (those round, leafy nests) and tree cavities are the main winter homes for your local squirrels. A drey is a bundle of twigs, leaves, and moss tucked into a branch fork, keeping out wind and light snow.
Tree cavities work even better for insulation. If a squirrel finds a hole in an old oak or maple, it might use it alone or share with others. You’ll see dreys 20–60 feet up, usually near good food sources, while cavities show up where branches broke or woodpeckers drilled.
Look for messy clumps of leaves in the trees, or small holes in trunks—those are the signs. These shelters let squirrels stay cozy for days and help them save precious calories when the nights get really cold.
Food Storage and Fat Reserves
Squirrels get busy in the fall, stashing nuts, seeds, and acorns all over their territory. You’ll notice scatter-hoarding—lots of tiny caches tucked under leaves, wedged into bark, or buried just under the soil.
They do this to spread out the risk. Sure, they’ll lose a few snacks to other animals, but most of their stash stays safe for winter.
Squirrels also pack on fat by eating a ton in late summer and fall. That extra chub carries them through those brutal cold snaps when food’s almost impossible to find.
When winter hits, they sometimes go into short torpor, dropping their metabolism for a few hours. But they don’t actually hibernate.
Want to spot their prep work? Watch for squirrels burying food like mad in autumn or making lots of trips to the same tree once it’s cold. If you’re hoping to help, try planting mast trees like oaks or just leave fallen nuts where they are. That little bit can make things way easier for your local tree squirrels.
