Photo by Jonathan Derbridge A Mount Graham red squirrel.

Happy Squirrel Appreciation Day! 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.

Squirrel Species

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.