Unlike many of these animal-related holidays, this is one that many of us can celebrate in our own backyards — and there’s a lot more to appreciate about these familiar creatures than you might expect.
Mention squirrels and you probably picture the eastern gray, but there are many species — 285, to be precise, according to John L. Koprowski, Ph.D., professor of wildlife conservation and management at the University of Arizona. He has devoted his career to studying squirrels, and he says that if you want to see a lot of them, you may not have to go too far.
“In North America, we have some of the greatest diversity of squirrels in the world outside of the tropics,” says Dr. Koprowski. “In southeast Asia, they can have over 50 species of squirrels in a single forest — if you love squirrels, that’s where you want to go — but the U.S. is a pretty good place to be.”
To start, we have plenty of the familiar eastern gray squirrel that lives in cities across much of the country. Native to the East Coast, they’ve also been introduced to many cities on the West Coast, including L.A.,Seattle and Vancouver, Wash.,he says.
But the cities in the West are also home to their own native ground squirrels, and in Midwestern cities you may see the orangish-brown fox squirrel. Dr. Koprowski studies several species in Arizona, including the Abert’s or tassel-eared squirrel, which is about twice the size of an eastern gray, with huge tufts of hair on its ears. Another striking-looking species is the Mexican fox squirrel, whose range reaches up into a small part of Arizona. “They’re gorgeous animals with a rust-colored stomach and a multicolored tail with cream, white and black and some orange,” he says.
The ground squirrels also include familiar animals that you might not know are also members of the squirrel family: chipmunks, prairie dogs and one that has its own special holiday, the groundhog (also called marmot and woodchuck). Then there are the flying squirrels, which don’t exactly fly but get around by launching themselves from one branch to glide to another. They’re rarely seen because they’re nocturnal, unlike most of their relatives.
“It’s an amazing diversity — from animals that burrow in the ground and hibernate to those specialized for travel in the trees to those incredibly linked to trees, like the flying squirrel that has to have those launching points,” Dr. Koprowski says.
We may think of squirrels as common, but that’s not true of all the species. The Delmarva fox squirrel in the East and the Mount Graham red squirrel that Dr. Koprowski studies are both federally listed endangered species.
Squirrel and Human Similarities
Although it's not rare, the squirrel that is our urban neighbor is well worth watching. Dr. Koprowski says that the gray squirrel does well in cities because it has the same opinions about property values as we do.
“The kinds of things that squirrels value are the same kinds of things that humans value in cities,” he says. The big shade trees that make a park or city street look attractive to us provide a habitat for squirrels, producing food and providing nice cavities for nests.
Cities also expose squirrels to threats like dogs and cars, so urban life can be a case of living fast and dying young for these rodents. But the large numbers give us humans a chance to watch interesting wildlife behavior without ever leaving town.
Squirrels have an amazing memory and sense of smell, which they use for finding the food that they stash. “They have traditional sites they like to visit and bury their nuts — they tend to remember those locations,” Dr. Koprowski says. “As they get close to those locations, they use the sense of smell.” Some experiments have shown that squirrels can even locate nuts by smell through a heavy layer of snow.
They’re also astute about how they treat the food they bury. Dr. Koprowski says that in some species of oak, the acorn sends out a little taproot inside its shell in the fall, to give the seedling a head start in the spring. Good for the baby tree, but not for the squirrel. “The problem with that from the squirrel’s perspective is that the nutrient quality of the seed starts to decrease because it puts that energy into the root,” Dr. Koprowski says.
So for the species that put out roots, the squirrels actually chip a little hole in the shell and clip out that part of the seed before they bury the nut — and for other oak species, they don’t bother. “They have an incredibly intricate ability to assess the health and energetic content of the seed, as well as identify what species,” he says.
Something that people tend to find surprising about gray squirrels is that they are social animals. “Some of the ground squirrels are really highly social — almost everyone’s seen a picture of a couple of prairie dogs standing together and grooming each other,” he says. “Gray squirrels do the same things but do it up in the trees.”
Two or three generations of females will nest together, especially in the winter. “They groom each other and remove parasites; they will help defend nests together,” he says. “They’ll go out and collect leaves together to use as insulation.”
Squirrels also use their amazing sense of smell for social communication by scent, marking their favorite pathways with glands in their cheek. “It looks like they’re just wiping their face, but if you watch, they do it in the same place every time they go by it,”Dr. Koprowski explains. “Other animals will visit those sites and identify who’s in the area that way.”
We’re not aware of their elaborate social lives because in the daytime, when we can easily observe them, they’re running around on their own, gathering and burying food. But if you find a nest and know when to look for them coming back at night, squirrels can be fascinating to watch, he says: “The things we see them do tend to be solitary activities, but there’s this whole hidden secret life going on that’s interesting for people who like watching animal behavior.”