You might picture all squirrels curling up and snoozing away the winter, but honestly, it’s not that simple. Some ground squirrels actually go into true hibernation—they drop their body temperature and slow their hearts way down—but most tree squirrels stay up, nap a lot, and depend on stashed food and warm nests.
As you read on, you’ll spot the real difference between true hibernation and winter dormancy. You’ll also see how the squirrels in your neighborhood manage to make it through the cold months.
Expect some straightforward but surprising facts about how they save energy, hide snacks, and use nests to stay alive.
How Squirrels Hibernate: True Hibernation vs. Winter Dormancy
You’ll get the main differences between deep hibernation and short-term dormancy. Some squirrels use one, some use the other.
Let’s look at which squirrels do what, what changes happen in their bodies, and how long these states last.
What Is Hibernation and Torpor?
Hibernation is a long, seasonal shutdown. The body temperature, heart rate, and metabolism drop a lot and stay low for weeks or even months.
True hibernators sleep deeply and live off stored fat. They don’t eat or drink for long stretches underground.
Torpor is different. It’s a short-term, energy-saving trick. A squirrel in torpor slows its metabolism for hours or a few days, then wakes up to eat or run around.
Tree squirrels use torpor during cold snaps. Torpor lets them survive sudden storms, even if they don’t have big fat reserves like ground squirrels.
Quick comparison:
- Hibernation: long, deep sleep, fueled by fat, usually in burrows.
- Torpor: short, reversible, common in many tree squirrels and some ground species.
Which Squirrel Species Truly Hibernate?
Not every squirrel hibernates. Ground squirrels are the real hibernators here.
Species like the Arctic ground squirrel and the thirteen-lined ground squirrel (Ictidomys tridecemlineatus) spend months in hibernation down in their burrows. They seal up their tunnels and stay hidden until spring.
Tree squirrels—including eastern gray, fox, and flying squirrels—don’t go into true hibernation. Instead, they stash food in dreys or middens and use torpor on the coldest days.
Red squirrels often defend a big food cache instead of hibernating.
If your yard looks quiet in winter, ground squirrels are probably sleeping in their burrows. Tree squirrels, on the other hand, hide in nests but still pop out when it warms up a bit.
Physiological Changes During Hibernation
When ground squirrels hibernate, their body temperature can drop from around 37°C (99°F) to nearly freezing. Their heart rate plummets—from hundreds of beats per minute down to just a few.
Their metabolism slows so much that fat alone keeps them going for months.
Hibernating ground squirrels use less oxygen and cut blood flow to organs they don’t need for survival. Every so often, they wake up a little, raise their temperature and heart rate, then slip back into torpor.
These brief wake-ups burn energy but help clear out waste and keep organs healthy.
Tree squirrels in torpor show milder changes. Their body temperature and heart rate drop for just a short time.
They wake up quickly to grab food or escape predators. This quick bounce-back helps them survive above ground.
Duration and Timing of Squirrel Hibernation
Ground squirrels hibernate based on local weather and food. In the far north, the Arctic ground squirrel can hibernate for five to seven months.
The thirteen-lined ground squirrel usually hibernates for several months, heading underground in late fall and coming out in spring.
Torpor in tree squirrels doesn’t last that long. It usually goes on for just a few hours or maybe a day or two, mostly during the harshest nights or storms.
Down south, many squirrels stay active all year and only use torpor during rare cold spells.
Where you live and how harsh the winter gets will decide when squirrels go dormant. Burrows and fat are key for long hibernation, while stored food and nest insulation matter more for squirrels relying on torpor.
If you’re curious, check out more on tree-squirrel behavior and torpor at Do Squirrels Hibernate? The Truth About Their Winter Behavior (https://squirrelsinfo.com/do-squirrels-hibernate/).
Winter Survival Strategies of Non-Hibernating Squirrels
Squirrels mix slow activity, careful food storage, and cozy nests to get through the cold. Here’s how they save energy, stash food, build shelters, and use body and habitat tricks to stay warm.
Energy Conservation and Winter Behavior
Tree squirrels like eastern gray and fox squirrels cut back on movement when it’s cold. You’ll notice fewer long dashes and more quick trips from the drey to check food stashes or grab a snack if it’s sunny.
They slip into short torpor spells—just hours at a time—not full hibernation.
You might see them resting more during the day, soaking up sun in sheltered spots, or huddling tight in their nests when storms hit.
Baby squirrels that make it to late autumn depend on their mother’s care and stored fat. Juveniles who don’t pack on enough reserves stick close to shelter.
These habits help them save energy but still let them forage if the weather improves.
Food Storage: Caching and Fat Reserves
Squirrels have two main ways to keep food handy: scatter-hoarding and larder-hoarding.
Gray and fox squirrels usually hide single nuts all over their territory. Red squirrels and some flying squirrels prefer to keep a big stash in one place.
You’ll often catch scatter-hoarders burying acorns and walnuts in dozens of tiny holes. This spreads the risk but means they need a sharp memory.
Before winter, squirrels eat as many high-calorie nuts and seeds as they can. That fat helps them get through cold nights and fuels those quick torpor naps.
When you spot a squirrel digging in leaves or snow, it’s probably after a buried nut—using landmarks and their sense of smell.
Reliable food caches and body fat together help them survive when it’s too cold to forage.
Nesting Habits: Dreys, Burrows, and Communal Nesting
Squirrels pick different shelters depending on their species and where they live.
Tree squirrels often build dreys—round nests made of twigs and leaves—in the crooks of branches. The inside is lined with moss, grass, or shredded bark, which traps air and holds warmth.
Eastern gray squirrels usually keep a few dreys around their territory for extra safety.
Some squirrels use tree cavities or old woodpecker holes when they find them. These spots offer better protection from wind and predators.
Ground squirrels and flying squirrels might use or share burrows.
When it gets really cold, you’ll sometimes find several squirrels sharing a drey or den to stay warm. Communal nesting happens a lot with young females and in species like flying squirrels, where sharing heat makes a big difference.
Adaptations: Insulation, Winter Coats, and Habitat
Squirrels change both physically and in where they live to stay warm. As winter creeps in, their fur thickens into a dense coat. The underfur traps air, which helps insulate them, while longer guard hairs keep wet snow off.
Sometimes you’ll notice their tails look darker or fuller in the cold months. Squirrels often wrap their tails around themselves for a bit of extra warmth. Young squirrels, though, don’t always have that full winter coat, so they rely more on nest insulation and their mom’s body heat.
Where squirrels choose to live matters a lot. In mature woods, they use tall trees and thick canopies to block the wind. City squirrels get creative, squeezing into attics or any insulated crevice they can find when trees aren’t around.
If you look closely at suburban dreys, you’ll spot nests lined with feathers, scraps of cloth, or whatever soft stuff they can gather. These little touches make the nests warmer. All these habits and changes help squirrels stay active on milder days and ride out the worst winter storms.
