Ever wondered if squirrels just disappear all winter or snooze away the cold months? Turns out, most tree squirrels don’t actually hibernate. Only some ground squirrel species go into true hibernation, so the squirrels you spot in your backyard are probably busy hiding food and hunkering down in their nests. Let’s dig into which squirrels sleep through winter, which ones stay active, and why they do things so differently.
You’ll find out when certain ground squirrels slip into deep torpor and how tree squirrels manage to get by without hibernating. It’s kind of fascinating to notice the signs of each survival strategy in your own yard as the seasons shift.
When and Which Squirrels Hibernate
Let’s talk about which squirrels truly hibernate, how their bodies change, and when they actually sleep through the cold. Ground squirrels go into deep hibernation, while tree squirrels just slow down and rely on their food stashes.
What Is Hibernation in Squirrels?
When squirrels hibernate, they slow their bodies way down to save energy when food is hard to find. Their heart rate, breathing, and body temperature all drop—sometimes to wild extremes.
For example, the arctic ground squirrel can cool itself almost to freezing. That trick lets it live off stored fat instead of braving the cold for food.
Hibernation isn’t just a quick nap or a short rest. Torpor, which lasts hours or maybe a day or two, lets an animal wake up pretty easily. But in true hibernation, a ground squirrel can stay in this deep sleep for weeks or even months, only waking up now and then. If you’re watching squirrels in winter, it’s a good idea to know the difference.
Ground Squirrels vs. Tree Squirrels
Ground squirrels dig burrows and usually hibernate. Tree squirrels, on the other hand, build nests in trees or hide out in cavities but rarely hibernate deeply.
Tree squirrels slow down and take shorter rests, sometimes for a day or two, and depend on their hidden food to get by. Ground squirrels like the arctic ground squirrel or the thirteen-lined ground squirrel (Ictidomys tridecemlineatus) rely on long stretches of dormancy.
Tree squirrels—gray, fox, and red—put on weight, grow thicker coats, and stay active enough to find food on warmer days. So, if you see squirrels in your backyard, they’re probably tree squirrels and not true hibernators.
Species That Hibernate
Many ground-dwelling squirrels are obligate hibernators. The arctic ground squirrel hibernates deeply, sometimes lowering its body temperature to almost 0 °C.
The thirteen-lined ground squirrel and the California ground squirrel also hibernate in cold places. Tree squirrels don’t make the list.
Gray, red, and fox squirrels use food caches and go into shallow torpor. If you spot a squirrel in your attic or a nesting box during winter, it’s probably a tree squirrel staying somewhat active. For more on this, check out how some ground squirrels must hibernate while tree squirrels adapt in other ways (https://wildyards.com/do-squirrels-hibernate/).
Timing and Duration of Hibernation
The timing of hibernation depends a lot on the species and the climate. Ground squirrels start prepping in late summer and usually settle in by September or October.
Many ground squirrels stay dormant all winter and come back out in March or April as things warm up. The length of hibernation can really vary.
Some ground squirrels sleep for months; arctic ground squirrels can stay dormant for up to eight months in harsh climates. Tree squirrels, though, have shorter, less predictable rest periods and will get up to eat their stored nuts when the weather isn’t too brutal.
If you’re keeping an eye on local wildlife, remember that colder places push animals to stay dormant longer.
How Squirrels Survive Winter Without True Hibernation
Squirrels face winter by keeping warm, saving energy, and making sure they have enough food. They don’t hibernate deeply like ground squirrels.
Instead, they rely on their nests, body changes, and clever food storage to make it through.
Nesting Behavior and Dreys
You’ll spot dreys tucked high in tree forks or inside hollow trunks. These round nests, built from twigs, leaves, moss, and sometimes a little bark or grass, can be surprisingly cozy.
Gray and fox squirrels make dreys about 6–12 inches across, lining them with softer stuff to hold in heat. Squirrels pick spots that block the wind and, if they can, face south for extra warmth.
Tree cavities give even better shelter, so you might see squirrels using holes during the coldest stretches. Southern flying squirrels often nest together to share warmth, but gray and fox squirrels usually sleep alone or with a small family.
Squirrels spend fall fixing up their dreys to keep them snug. You’ll probably notice them hauling nesting material in late summer and early fall.
Good nests mean fewer cold-night wakeups and less need to wander far from their food.
Fat Storage and Body Changes
Before winter hits, squirrels eat more to build up some fat reserves. They don’t get as chunky as true hibernators, but they do put on weight to ride out the harshest days.
This extra fat gives a steady energy source during slower times. Squirrels also grow thicker winter coats, with denser fur and sometimes a puffier tail.
The thicker fur helps them keep warm, and the tail can even act as a little blanket when they curl up. Unlike true hibernators, their body temperature only drops a bit during rest, not to the point of freezing.
Your local gray or fox squirrel will cut back on activity during the coldest hours. They make small, controlled drops in metabolism and heart rate, but they’ll still get up to check their food or grab a snack.
This flexible way of dealing with winter helps them stay alert if the weather suddenly warms up—or if hunger strikes.
Food Hoarding Strategies
You’ll probably spot squirrels burying nuts and seeds all over the place as late summer rolls into fall. They scatter-hoard—basically, they stash food in lots of different spots so if a predator finds one, the rest stay safe.
Gray and fox squirrels can make hundreds, sometimes even thousands, of these little caches every season.
Squirrels use their memory and sense of smell to track down buried snacks. They’ll often check on their favorite stashes and might even hide things again if something seems off.
Not every cache gets found. Sometimes, forgotten seeds sprout into new trees, which is actually pretty great for the forest.
When food runs low, squirrels dig into their hidden supplies and do some speedy foraging during the day. They go for stashes they can reach easily from their dreys.
If you look near the base of trees, you might catch them digging in the leaf litter. That’s where a lot of their winter food is tucked away.
Curious about how other squirrel species handle things? Here’s a look at how hibernating ground squirrels conserve water and energy: https://www.science.org/content/article/here-s-how-hibernating-squirrels-live-months-without-water.
