Ever wonder if squirrels really sleep the whole winter away, or if they just vanish into the trees? Most tree squirrels don’t hibernate in the classic sense—they slip into short torpor spells and count on their food stashes and snug nests to get through the coldest days. That’s why, on a sunny January afternoon, you might spot a squirrel darting across the snow, while ground squirrels seem to disappear for ages.
Some squirrels go in for full-on hibernation underground, but others get by with torpor, food caches, and even group snuggling. I’ll walk you through which ones do what, plus when and where they hole up, and the clever tricks they use to hang on until spring.
How Do Squirrels Hibernate?
Some squirrels drop into deep, months-long sleep. Others just take short, energy-saving breaks and snack on hidden food.
It really depends on the species. They have different body changes and nesting habits to survive the cold.
Differences Between Hibernation and Torpor in Squirrels
Hibernation means an animal’s metabolism, heart rate, and body temperature all drop way down for a long stretch. Ground squirrels like the Arctic ground squirrel and the thirteen-lined ground squirrel (Ictidomys tridecemlineatus) actually hibernate.
They curl up in their burrows for months, living off body fat.
Torpor, on the other hand, is brief and you can reverse it. Tree squirrels—like eastern gray squirrels, fox squirrels, red squirrels, and flying squirrels—use torpor.
They slow their metabolism for hours or a day or two, then wake up to eat. That’s why you’ll sometimes see them out and about on warmer winter days.
You can spot the difference by looking at how long they stay inactive (months vs. hours), how much their temperature drops (ground squirrels get close to freezing, tree squirrels don’t), and whether they wake up to eat (tree squirrels do; ground squirrels mostly don’t).
Which Squirrel Species Hibernate
You’ll find true hibernators mostly underground. The arctic ground squirrel and other ground squirrels hibernate deeply.
The thirteen-lined ground squirrel is a textbook example. These squirrels dig in for the winter in late fall and don’t really stir until spring.
Tree squirrels, like eastern gray squirrels, fox squirrels, and red squirrels, stay somewhat active through winter. Flying squirrels skip hibernation too; they often pile into nests together and go into torpor for short stretches.
Your backyard gray squirrels probably nap through cold nights but pop out to dig up nuts on warmer days.
Location makes a difference too. In really cold places, more squirrels hibernate for longer.
But in milder climates, even ground squirrels might shorten their hibernation or not bother at all. If you know which squirrel lives nearby, you’ll have a good idea how it spends the winter.
Physiological Changes During Hibernation
During real hibernation, a ground squirrel’s body temperature drops almost to freezing. Heart rate and breathing slow way down.
Their metabolism plummets, so they can live off stored fat. Arctic ground squirrels take this to the extreme—their body temperature can get shockingly low.
Tree squirrels in torpor don’t go as far. They lower their metabolism and body temperature just a bit.
Their heart rate slows for a while, but they can wake up fast if they need to. When they do, they munch on their hidden food to get energy back.
Flying squirrels sometimes nest together to share body heat, so they don’t need to slow down as much.
Both hibernation and torpor save energy and help squirrels hold onto water. Ground squirrels avoid freezing and thawing by staying deep in their burrows.
Tree squirrels rely on leafy nests or tree holes and wake up now and then to eat or groom.
Winter Nesting and Survival Strategies
Ground squirrels dig insulated burrows with plugged entrances. You’ll usually find these nests lined with plants to keep in warmth.
Burrows keep predators out and the temperature steady, so ground squirrels can stay in torpor for months.
Tree squirrels build dreys—those round, leafy nests high up in trees—to block wind. Eastern gray squirrels, fox squirrels, and red squirrels also use hollow trees for extra warmth.
Flying squirrels like tree cavities and often nest in groups for body heat.
Food storage is a big deal. Tree squirrels scatter nuts all over the place.
They use their noses and memories to find them again in winter. Red squirrels make big, central piles of cones and defend them.
You’ll probably spot squirrels on milder days, rooting around for these hidden snacks.
Squirrel Adaptations for Winter
Squirrels really mix things up when it comes to eating, sleeping, and keeping warm in winter. They stash food, build sturdy nests or burrows, bulk up their insulation, and somehow even manage to raise babies in the cold.
Food Storage and Foraging Habits
Squirrels scatter-hoard—meaning, they bury tons of little food stashes all over the place. Gray squirrels and fox squirrels love to hide acorns and walnuts not too far from their nests or favorite trees.
This way, if a thief finds one cache, there are plenty more left.
They use smell and memory to dig up their snacks later. Some forgotten nuts even sprout into new trees, which is kind of neat.
When food gets scarce, squirrels might raid bird feeders, compost bins, or gardens. Red squirrels guard their cone piles, while flying squirrels keep food tucked away in tree holes.
If you want to keep squirrels out of your yard, locking down bird feeders helps. Watching their foraging can help you guess when they’ll be most active.
Building and Maintaining Dreys and Burrows
Squirrels pick their shelters based on their species and where they live. Tree squirrels like gray and red squirrels build round dreys from twigs, leaves, moss, and fur.
You’ll find these high up, wedged into branches for safety.
Some squirrels opt for tree cavities instead. Flying squirrels and some fox squirrels use hollow trunks or even attic spaces to stay warmer.
Ground squirrels dig burrows with cozy chambers below the frost line. They patch up nests before winter, adding fresh leaves and soft stuff.
A drey in use looks packed tight with new nesting fur. If squirrels sneak into your attic, wait until late summer—after babies leave—before sealing things up.
Staying Warm in Cold Temperatures
Squirrels rely on body fat, thick fur, and smart habits to stay toasty. In fall, they bulk up and their fur grows fluffier, trapping more air for insulation.
Behavior helps too. Many squirrels nap together in nests or tree holes; southern flying squirrels are famous for group huddling.
When it’s bitterly cold, squirrels stay put and only dash out for food on milder afternoons. Deep burrows stay above freezing, so ground squirrels get steady warmth.
If you watch closely, you’ll see squirrels curl up tight or drape their tails over their backs to block the wind. These simple tricks help them keep warm—even without full hibernation.
Care of Baby Squirrels During Winter
Baby squirrels born late in the year face extra risks. Adult squirrels do what they can to protect them.
You’ll usually see mothers pick the warmest shelter they can find—deep tree cavities or well-lined dreys—to raise their pups. They gather soft materials, like shredded bark and fur, to line the nests and keep the babies warm.
When cold snaps hit, mothers cut down on outside trips. They eat more to keep up their milk supply.
Older juveniles sometimes crowd together in nests for extra body heat. In flying squirrel colonies, several related females might pitch in to help with the young, which definitely gives the babies a better shot at survival.
If you stumble across an unattended baby squirrel, try not to handle it unless you really have to. Usually, you can restore warmth just by returning the baby to its nest.
If things don’t improve, it’s best to reach out to a local wildlife rehabilitator. That way, the baby gets the right care without you accidentally disrupting the family group.
