[Reprint from November 2010]
Winter winds have blown nearly all the remaining leaves to the ground. They lie tossed and trampled on the ground like post-holiday parade confetti. The hyperbole of autumn reds and oranges and yellows is long gone, replaced by browns, taupes, and grays.
But bare boughs and blue skies offer the perfect opportunity to pull back that leafy curtain for a peek “behind the scenes.” All you need to do is step outside… and make the leap from two dimensions into 3D.
Sure, we all know it’s a three-dimensional world, but with the exception of a flight of stairs now and then human days are usually spent in a forward-backward-left-right routine. Skeptical? Spend even a few minutes watching a gray or fox squirrel ricochet between branches and you’re guaranteed to feel like your days are spent in Flatland.
Unlike many mammals, squirrels make it easy for wildlife watchers. They’re not shy, they’re active during the day, and much of their activity occurs within the visual field between our feet and our face. Of course, while we keep our feet planted firmly on the ground squirrels do not, and when they bolt up the bole into dense foliage they seem to disappear like a Santa up a chimney. What good does it do to look up?
Two dreys in a silver maple (Photo: KJ Lindsey, CCL 2.0)
In parts of the country that have both squirrels and seasons when trees go au naturel, craning one’s neck can be more rewarding during the winter months. That’s why I’m trying to cultivate a new habit during walks with my terrier-boy, Dash. Whenever I catch myself contemplating my shoes, which is often, I lift my eyes and scan the trees, starting at about the same level as the roof of a two-story house. Try it yourself. See those seemingly accidental wads of leaves and twigs, about the size of a football, caught in the gutters formed by branches? Those are squirrel nests, also known as dreys.
Squirrels aren’t as famous for their engineering skills as are beavers but maybe they should be. It can’t be easy to build 20 feet or more above the ground on a foundation that sways with every breeze. Construction begins with a platform of woven twigs, followed by a spherical framework secured to the base. Leaves, paper, and moss are used to fill in the gaps and create a snug, weatherproof abode with two doorways—a main entrance and a hidden escape hatch. The exterior may look a little rustic but the interior décor is luxurious. Lined with fur, feathers, and other cozy furnishings, it’s the perfect cocoon for a cold winter’s night.
Close up of a drey (© N. Hawekotte, used with permission)
Squirrels don’t hibernate but they do lie low during inclement weather. When the mercury drops or the snow starts to fly, a group of females may crowd into a single drey, kind of like a slumber party without the pajamas, pizza, and prank phone calls.
As spring approaches, the dreys serve a dual purpose as nurseries for the new crop of infants. I realize not everyone is a tree squirrel fan, but if you’re an aficionado and want the scoop on where to enjoy watching for youngsters when they venture out to explore the world and learn how to navigate in every direction, now’s the time to make note of which trees are littered with messy nests.
Just think 3D… without the funny glasses.
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My filed and brightly polished toenails would have to go, replaced by strong, sharp claws that could easily pierce porous bark or hook onto an uneven edge (completely impractical for someone who wears socks and sleeps under a blanket, though). Whereas humans, including me, need at least three points of attachment when climbing, this adaptation allows squirrels to secure their position with only two attachment points, and to grasp new surfaces at angles most animals would find impossible.
Understandably, early aviation experiments centered around mimicry of birds, complete with flapping arms that were usually covered in feathers. The Greek legend of Daedalus and Icarus is a familiar example, but plumage continued to be part of the trial-and-error approach through the first years of the 19th century, when a tailor named Albrecht Berblinger constructed an ornithopter and then took an ill-fated plunge into the Danube. Those daring young men with their dreams of flying machines… they just didn’t understand the concepts of thrust, lift, and drag, and they couldn’t let go of the idea that soaring requires feathers.
Cope’s and Eastern are equally skilled at clinging to and climbing slick surfaces using large toe pads that secrete mucous, creating surface tension. It’s not uncommon to find one plastered against a window pane (allowing for an interesting view of their nether-regions). Both species prefer a diet of small insects, spiders, and snails. Both hibernate under leaves, bark, or rocks. Well, “hibernate” sounds a lot more cozy than the reality… which is that their bodies pretty much freeze and their lungs, heart, brain, and other organs stop working until they thaw out and reanimate in the spring. It’s a pretty nifty chemical trick, on par with being able to transform your complexion at will. 
Kermit has an unmistakable personal brand, but distinguishing H. versicolor from H. chrysocelis visually is just about impossible. Both Eastern and Cope’s are relatively small (1.5—2.0 in/3.5—5 cm), and the adults are often mistaken for younglings. Both wear a sweep of bright citrus-orange along the inseam of their hind legs (a signature shade is all the rage, you know). Females of both species are usually (but not always) larger, with a ladylike white throat. During the breeding season, males have a macho (make that hipster, since it resembles a beard) black, gray, or brown throat. Guys sing. Gals swoon, but don’t sing along.
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