Do Squirrels Hibernate? Winter Behavior Guide

Do Squirrels Hibernate?

It depends on which squirrel you're asking about. Ground squirrels are true hibernators — they shut down for months at a time with body temperatures near freezing. But the gray, fox, and red squirrels in your backyard don't hibernate at all.

When your neighborhood squirrels vanish for a few days during a snowstorm, they aren't hibernating. They're curled up in their nests in a lighter rest state called torpor, waiting out the worst of the weather. Give them a sunny day and they'll be back digging up buried nuts like nothing happened.

So the honest answer: some squirrels hibernate deeply, and some just nap through the cold. Here's how to tell which is which — and what it means for the squirrels in your yard.

Which Squirrels Actually Hibernate?

Scientists split squirrels into two camps. Ground squirrels live in burrows and are built for deep winter sleep. Tree squirrels live in nests above ground and stay awake through winter.

Here's how the main North American species break down:

Species	Type	Hibernates?	How Long
Arctic ground squirrel	Ground	Yes — deepest sleep of any mammal	7–8 months
Columbian ground squirrel	Ground	Yes	7–8 months
Thirteen-lined ground squirrel	Ground	Yes	5–6 months
California ground squirrel	Ground	Yes (in colder parts of its range)	4–5 months
Eastern gray squirrel	Tree	No — uses torpor	—
Fox squirrel	Tree	No — uses torpor	—
American red squirrel	Tree	No — guards a food cache	—
Flying squirrels	Tree	No — huddle for warmth	—

The key split is simple: if it lives underground, it probably hibernates. If it lives in a tree, it doesn't.

What Happens Inside a Hibernating Squirrel?

True hibernation is one of the most extreme things a mammal can do. A ground squirrel doesn't just fall asleep — it nearly shuts its body off.

Body temperature plummets

A ground squirrel's normal body temperature is around 99°F (37°C), about like yours. During hibernation it drops to just above freezing. The Arctic ground squirrel has been measured at 27°F (-3°C) — the lowest body temperature ever recorded in a mammal. Its blood should freeze solid at that point, but special adaptations keep it liquid.

Heart rate slows to a crawl

An active ground squirrel's heart beats over 300 times per minute. In deep hibernation it drops to as few as 5 beats per minute. Breathing slows too — down to a breath or two per minute, with long pauses between breaths.

They run on fat alone

Before hibernation, ground squirrels eat constantly and can nearly double their body weight. That fat layer is their only fuel for months. Their metabolism burns it so slowly that a few pounds of fat can last an entire winter.

They wake up periodically

Here's the part most guides skip: hibernating squirrels don't sleep straight through. Every week or two, they warm back up to normal body temperature for a few hours, then cool down again. Scientists call these "interbout arousals," and they're still debating why they happen — one leading idea is that the brain needs brief warm periods to clear waste and repair itself. These short wake-ups burn a huge share of the winter's energy budget.

During deep hibernation, a squirrel is almost impossible to wake. It feels cold and limp, and it won't respond to touch. Don't try to wake one. Every arousal burns fat it can't replace until spring.

What Do Tree Squirrels Do Instead?

The gray and fox squirrels in your yard take a completely different approach: prepare in fall, endure in winter. No deep sleep required.

Scatter-hoarding: thousands of hidden snacks

In autumn, gray and fox squirrels enter a frantic caching phase. They bury nuts and acorns in thousands of individual hiding spots across their territory — one nut per hole, spread out so a thief can't steal the whole stash at once. Their spatial memory is remarkable: studies show they recover a large share of these caches through winter, and they can even smell nuts buried under snow.

Torpor: short rest breaks

When a real cold snap hits, tree squirrels retreat to their nests and enter torpor — a light, short-term slowdown. Unlike true hibernation, torpor lasts hours or a couple of days, and body temperature drops only slightly. A squirrel in torpor wakes up quickly if disturbed or when the weather breaks.

Red squirrels: one giant pantry

American red squirrels skip the scattering strategy. They build a single massive food pile called a midden — often in a cool, damp hollow log that keeps cones and nuts fresh. Then they defend it fiercely all winter. Mess with a red squirrel's midden and you'll hear about it.

Flying squirrels: warmth in numbers

Flying squirrels don't hibernate either. Their trick is social: up to 20 or more will pile into one tree cavity and share body heat through the coldest nights. It's called communal nesting, and it works.

How do they find buried nuts under snow?

This is the part that surprises most people. A gray squirrel can bury up to 10,000 nuts in a single autumn — and recover a large share of them months later, even under snow. They use two tools: spatial memory (they remember landmarks near cache sites) and smell (they can detect a buried acorn through a foot of snow). They also steal from each other constantly, which is why scatter-hoarding works — no single theft wipes them out.

Dreys vs. cavities

Tree squirrels shelter in two kinds of nests. A drey is a rough ball of leaves and twigs wedged into tree branches — fine for mild weather. A cavity is a hollow inside the trunk — much warmer, and the preferred winter shelter. In neighborhoods, squirrels will also happily move into attics and wall voids, which is why winter is peak season for squirrel-in-the-attic complaints.

When Do Squirrels Hibernate? Month by Month

For ground squirrels, hibernation follows a strict calendar. Here's what happens through the year:

August – September: Fattening up

Ground squirrels eat almost nonstop. They're building the fat reserves that have to last months, and they can nearly double their weight. You'll see them out at all hours, cheeks stuffed. Young squirrels born that spring stay active longest — they need extra time to bulk up.

October: Going down

As days shorten and nights turn cold, ground squirrels seal their burrow entrances with soil and grass. Body temperature starts to fall. Heart rate drops from over 200 beats per minute to fewer than 10. Adult males usually go down first; females and juveniles follow.

November – February: Deep sleep

The squirrel is fully out. Body temperature sits near freezing, and it burns stored fat at a crawl. Every week or two it warms up briefly (those interbout arousals), then cools back down. Meanwhile, tree squirrels are wide awake — caching, foraging on mild days, and taking torpor breaks during storms.

March – May: Waking up

Males emerge first, often weeks before females. They need the head start to claim territory and be ready when females wake. By late spring the whole colony is active again, and mating season follows close behind.

Hibernation calendar by species

Species	Enters Hibernation	Wakes Up	Total Sleep
Arctic ground squirrel	September	Late April – May	7–8 months
Columbian ground squirrel	July – August	March	7–8 months
Thirteen-lined ground squirrel	October	March – April	5–6 months
California ground squirrel	October – November	February – March	4–5 months

The Columbian ground squirrel sleeps longest — in high mountain areas, adults can be down by late July. That's over half the year underground.

Signs hibernation season is starting

Ground squirrels vanish from spots where you saw them all summer
Burrow entrances look freshly plugged with dirt and grass
Tree squirrels get extra busy — that's caching, not pre-hibernation
Daytime highs stay below 50°F (10°C) for a week or more

Signs spring wake-up is near

Fresh diggings appear around old burrow entrances
You spot a lone ground squirrel on a warm afternoon — likely a male scouting
Tree squirrels start chasing each other — mating season follows hibernation season

How Does Location Change Things?

Where a squirrel lives matters as much as what species it is. Winter in Florida and winter in Minnesota are different worlds.

Southern states: barely a pause

In places like Florida and Texas, winters are mild and food stays available. Squirrels here remain active year-round. They might hole up during a rare cold snap, but there's no hibernation and barely any torpor. A January squirrel in Miami is just living its normal life.

Northern states: the full shutdown

In Michigan, Minnesota, and New England, winters are long and brutal. Tree squirrels spend serious stretches in torpor, emerging only on milder days. Ground squirrels vanish for months. If you live up north and your squirrels disappear in November, that's normal — not a sign something's wrong.

The California exception

California ground squirrels show how flexible this gets. In colder inland areas they hibernate through winter. In mild coastal zones, some populations skip winter hibernation entirely — and may instead go quiet during hot, dry summers, a state called estivation. Same species, different strategy, depending on the local climate.

Squirrels vs Chipmunks: Who Really Hibernates?

People lump chipmunks in with squirrels, but their winter game is different. Chipmunks are true hibernators — they retreat to burrows and enter deep sleep like ground squirrels.

There's one big difference, though. Ground squirrels live off body fat alone. Chipmunks wake up every few days to snack from a food stash they've stored inside the burrow, then go back to sleep. They're hibernators with a pantry.

So if you see a chipmunk pop out on a mild February day, it didn't end hibernation early — it was just grabbing lunch.

Frequently Asked Questions

Do squirrels hibernate in winter?

Some do. Ground squirrels hibernate for 4–8 months in a deep sleep with near-freezing body temperatures. Tree squirrels — gray, fox, red, and flying squirrels — do not hibernate. They stay active all winter and take short rest breaks called torpor during cold snaps.

What month do squirrels start hibernating?

Most ground squirrels enter hibernation between August and October. Arctic ground squirrels start in September; California ground squirrels start latest, in October or November. Columbian ground squirrels in mountain areas can go down as early as July.

Where do squirrels go in winter?

Hibernating ground squirrels sleep in underground burrows dug below the frost line. Tree squirrels shelter in leaf nests (dreys) or tree hollows, and come out on mild days to dig up cached food. Some move into attics and wall voids.

How long can a squirrel hibernate?

Arctic and Columbian ground squirrels hibernate 7–8 months — among the longest hibernations of any mammal. Thirteen-lined ground squirrels sleep 5–6 months; California ground squirrels 4–5 months.

Can you wake a hibernating squirrel?

You shouldn't try. Waking burns a huge amount of stored fat, and a squirrel that arouses too often may run out of energy before spring. If you find one, leave it alone and keep pets and kids away.

Do gray squirrels hibernate?

No. Eastern gray squirrels stay active through winter. They survive on nuts buried in fall and take short torpor naps during the worst weather. If you see a squirrel in January, it's almost certainly a gray or fox squirrel.

What temperature do squirrels hibernate at?

Ground squirrels typically enter hibernation as soil temperatures drop into the 40–50°F (4–10°C) range and food grows scarce. Once down, their body temperature falls to just above freezing — Arctic ground squirrels have been measured at 27°F (-3°C).

Do squirrels hibernate in Florida?

No. Florida winters are too mild for hibernation. Squirrels there stay active year-round and only shelter briefly during unusual cold snaps.

Why don't I see squirrels in winter?

Three likely reasons: ground squirrels in your area are hibernating underground, tree squirrels are riding out a cold snap in torpor, or they're simply less active and foraging only during the warmest part of the day. They'll be back.

Sources

National Park Service — Ground squirrel hibernation and life history patterns
University of Alaska Fairbanks — Arctic ground squirrel body temperature research (lowest recorded mammalian body temperature)
California Department of Fish and Wildlife — California ground squirrel life history
Animal Diversity Web, University of Michigan Museum of Zoology — Species accounts for Urocitellus parryii, Ictidomys tridecemlineatus, and Sciurus carolinensis