How Do Squirrels Survive Extreme Cold? Four Mechanisms

No hibernation, no fat reserve worth speaking of. Dreys, cached food, huddling and a doubled winter coat are what gets them through.

By Zakaria November 2, 2026 2 min read Save to Pinterest

A grey squirrel in dense winter coat eating a nut on open snow — Photo: PublicDomainPictures, Pixabay Content License, via Pixabay

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Tree squirrels get through a northern winter on insulation and stored food, not on sleep and fat. That is an unusual strategy for an animal their size, and it has a specific failure mode.

The short answer

Tree squirrels do not hibernate — they stay active all winter, reducing activity for two or three days at a time in the worst weather while body temperature and metabolism stay normal. Four mechanisms carry them: a winter coat roughly twice as dense as the summer one, a tightly woven insulated drey with its entrance on the sheltered side, huddling with other squirrels on the coldest nights despite not being social animals otherwise, and wrapping the tail over the body. They find cached food under snow mostly by scent. Because they carry little fat, the limiting factor is energy rather than temperature: a long frozen spell or a poor mast year the previous autumn is what kills them.

No hibernation in tree squirrels; chipmunks and marmots do
Winter coat ~2× the density of summer
Dreys are insulated spheres, entrance away from the weather
They huddle, though they are not social otherwise
Energy, not cold, is the limiting factor

The four mechanisms

mechanism	effect
Dense winter coat	longer guard hairs, thicker underfur
Insulated drey	woven sphere, bark and moss lining
Huddling	shared body heat on the worst nights
Tail over the body	a blanket with its own insulation
Cached food	the energy that makes all of it work

Who hibernates and who does not

animal	winter strategy
Grey, red, fox squirrel	active all winter
Flying squirrel	active, huddles in large groups
Chipmunk	extended torpor, waking to eat cached food
Ground squirrel	true hibernation
Marmot, groundhog	true hibernation

Two days in the drey is not hibernation

A squirrel that is not seen for 48 hours during a blizzard has reduced activity, not reduced metabolism. It comes out as soon as conditions allow and goes straight to a cache.

Why late winter is the dangerous part

Autumn caches are finite and the squirrel has been drawing on them since November. By February and March the stores are depleted, the previous year’s mast crop is long gone, and no new food has appeared. A hard frost that locks the ground at that point is far more serious than the same frost in December.

If you feed at all, feed the right things

Unsalted nuts in shell, black oil sunflower and maize. Not salted or roasted nuts, not bread, not anything sweetened. And in Britain and Ireland, where greys are invasive and reds are protected, deliberately feeding greys is discouraged.

Common questions

Do squirrels hibernate through the cold?

Tree squirrels do not. Greys, reds and fox squirrels stay active all winter and are out foraging on most days, including in snow. What they do is reduce activity sharply in the worst weather, sometimes staying in the drey for two or three days at a stretch, which is not hibernation — body temperature and metabolism stay normal. Ground squirrels, marmots and chipmunks are the ones that enter true hibernation or deep torpor.

What keeps them warm?

Four things working together. The winter coat is roughly twice the density of the summer one, with longer guard hairs and thicker underfur. The drey is a tightly woven insulated sphere, often lined with shredded bark, moss and leaves, with the entrance on the sheltered side. They huddle — several squirrels that are not otherwise social will share a drey on the coldest nights. And they wrap the tail over the body as a blanket.

How do they find food under snow?

By smell, mostly, and by spatial memory for the general area. A grey can locate a buried nut under a substantial depth of snow by scent, which is why you see them digging confidently in places that look identical to everywhere else. They also cache in tree crevices and forks above the snowline, and strip bark and buds when ground caches are inaccessible.

Do they lose weight over winter?

Usually, and often substantially, which is one reason late winter is the hardest part of the year rather than midwinter. Squirrels put on some autumn fat but nothing like the reserve a hibernator carries, so they are running on cached food. A long frozen spell that locks the ground, or a poor mast year the previous autumn, is what kills them rather than the temperature itself.

How cold can they tolerate?

Well below freezing — greys and reds are active in conditions around and below -20°C, and the northern limits of their range sit in genuinely severe winter climates. The limiting factor is energy, not cold. An animal that can reach cached food and return to an insulated drey survives temperatures that would kill a comparable animal without those two things.

Should I feed squirrels in hard winter weather?

It is unnecessary in most places — they are equipped for it — and it has the usual costs of habituation. Where it is genuinely severe and prolonged, unsalted nuts in shell, sunflower seed and maize are what they handle; salted or roasted nuts, bread and anything sweetened are not. In Britain and Ireland, where greys are an invasive species displacing reds, deliberately feeding them is discouraged.

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A grey squirrel on a snow-covered branch in winter

Backyard Animals · Oct 12, 2026

How Do Squirrels Survive Extreme Cold? Four Mechanisms

The four mechanisms

Who hibernates and who does not

Why late winter is the dangerous part