A squirrel covers itself with its bushy tail as snow falls on and around it.

B.Y.O.B.

The squirrel sat perfectly still in the frigid air and falling snow.

I didn’t see any shivering, something squirrels can do to stay warm. The likely reason? He—or she—remembered to B.Y.O.B. You know… bring your own blanket.

As I write this post, it’s snowing, with six or more inches forecast by day’s end. Aside from the falling flakes, there’s no visible movement outside my window. The squirrels seem to be hunkered down. After watching and reading about their home-building habits, I can see why.

Squirrels are amazing little architects. You’ve no doubt seen their nests, called dreys, attached to tree branches. The ones they build for winter are made of leaves, layered to create watertight shingles, with mosses and other soft materials lining the interior. All that insulation traps a squirrel’s body heat so effectively that an occupied drey can be 60 to 85 degrees Fahrenheit warmer than the outside air. When a squirrel returns after leaving to seek food, it takes less than 30 minutes for that snug little home to warm up again.

Lots of squirrels in my backyard choose to nest inside tree cavities, which they line with moss and leaves. There’s often a leafy curtain covering the entry hole. After the squirrels enter, they shuffle the leaves to re-seal the opening. For added warmth, more than one squirrel may share a winter nest, whether in a drey or a tree cavity.

Here’s a video I made, showing some other ways squirrels deal with winter:

The first time I saw squirrels stretched out on a tree trunk, it took me a minute to realize what they were up to. Clever little solar heat seekers, don’t you think?

If you happen to be reading this during a snowstorm, I hope you’re snug and warm, like my squirrely neighbors.

Resources and a Related Kids’ Book

I may have shared this book before, one of my favorite nonfiction books for adults and advanced kid readers: Winter World, the Ingenuity of Animal Survival by Bernd Heinrich. It’s as fascinating as it is informative.

An online article, Squirrel Nests & Refugia, explains squirrel nests in greater detail than I included here.

And for kids, here’s a terrific picture book that explores how animals stay warm in winter:


In A Warm Winter Tail by Carrie A. Pearson, illustrated by Christina Wald, animals ask their mamas how humans stay warm in winter. Each young animal asks about its own winter adaptation, like the deer who wonders: Do humans grow hollow hair so the coats they wear trap the heat from their bodies for warmth? The mama deer responds, explaining that without hair coats, humans wear jackets with zippers and snaps. The book features mammals, reptiles, birds, and insects. The language is quite lovely—lyrical, rhyming lines that pack a lot of information into just a few words. The illustrations are beautiful, realistic depictions of the animals, plus fun drawings imagining how humans would look if they adopted the animals’ winter warmup strategies. The book ends with two fact-filled but fun-to-read pages that explain the details of animals’ winter adaptations. This book is currently in my TBW (To Be Wrapped) pile. I’m giving it to my youngest grandkids for Christmas and can’t wait to read it to them!

Image Credits: Carol Doeringer.

10 thoughts on “B.Y.O.B.”

  1. Thanks so much for this post! I had no idea how warm squirrels’ winter homes could be – especially those up in a leafless tree!

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