18 Things You May Not Know About Squirrels

These charismatic rodents are full of surprises.

squirrel eating an acorn
An urban squirrel enjoys lunch with a photographer on the University of California-Berkeley campus.

(Photo: Kai Schreiber/Flickr/CC BY-SA 2.0)

Squirrels get a lot of attention from humans, but not always for good reasons. We tend to dwell on negatives like stolen tomatoes and occupied attics, sometimes failing to fully appreciate the long, mostly harmless — and often entertaining — history of squirrels living in our midst.

This softer side deserves attention, too, especially since squirrels are among the most visible wildlife in many big cities and suburbs. They're widespread and widely liked, and despite a knack for mischief, rarely inspire quite the same scorn as other, more garbage-prone city animals like rats, pigeons, or opossums. They're like furry little forest ambassadors, using parks and backyards as their urban embassies.

Yet even for people who see squirrels every day, this diverse family of rodents can be full of surprises. Here are a few interesting facts you may not know about these charismatic opportunists who share our habitats.

1. Squirrels Are Surprisingly Diverse

eastern chipmunk
An eastern chipmunk plans its next move at Rock Creek Park in Washington, D.C. (Photo: Mr.TinDC/Flickr/CC BY-ND 2.0)

The squirrel family is among the most diverse of all modern mammals, with more than 270 species and 50 genera thriving everywhere from Arctic tundra and tropical rainforest to farms, suburbs, and big cities. It includes a variety of tree squirrels and flying squirrels, but also many ground-dwelling species — like chipmunks, prairie dogs, and marmots — that may be less obviously squirrelly to casual observers familiar with bushy-tailed acrobats. Nonetheless, they're all members of the taxonomic family Sciuridae, which is native to every continent except Australia and Antarctica.

2. The Biggest Squirrels Are 7 Times Larger Than the Smallest

Indian giant squirrel
The Indian giant squirrel is one of several giant squirrel species native to South Asia. (Photo: Atul Sinai Borker/Shutterstock)

Squirrels range in size from the 5-inch (13 centimeter) African pygmy squirrel to relative behemoths like Indian giant squirrel (pictured above) or China's red-and-white giant flying squirrel, both of which can grow more than 3 feet (almost 1 meter) long.

3. Their Front Teeth Never Stop Growing

squirrel teeth
A squirrel's four front teeth will keep growing throughout its life. (Photo: Puttinan Inchan/Shutterstock)

Squirrels have four front teeth that grow continuously throughout their lives, at a rate of about 6 inches (15 cm) per year. This helps their incisors endure the seemingly incessant gnawing.

4. They Have a Knack for Knocking Out Electricity

squirrel on power lines
'Frankly, the No. 1 threat experienced to date by the U.S. electrical grid is squirrels,' said John C. Inglis, former deputy director of the U.S. National Security Agency. (Photo: Ztudio-Neosiam/Shutterstock)

Electrical lines are no match for squirrel teeth, which have been blamed for hundreds of power disruptions across the U.S. in the past 30 years — including outages that briefly shut down the NASDAQ stock market in 1987 and 1994. As the Brookings Institution points out, "squirrels have taken down the power grid more times than the zero times that hackers have."

5. Solitary Tree Squirrels Warm Up to Each Other in Winter

Adult tree squirrels normally live alone, but they sometimes nest in groups during severe cold spells. A group of squirrels is called a "scurry" or "dray."

6. Prairie Dogs Build Bustling 'Towns'

black-tailed prairie dog pups
Black-tailed prairie dog pups hang out at South Dakota's Custer State Park. (Photo: Tom Reichner/Shutterstock)

The squirrel family also includes more sociable types. Prairie dogs, for example, are social ground squirrels with complex communication systems and large colonies, or "towns," that can span hundreds of acres. The largest town on record was a Texas colony of black-tailed prairie dogs that stretched about 100 miles (160 kilometers) wide, 250 miles (400 km) long and contained an estimated 400 million individuals.

7. The Word 'Squirrel' Comes From Greek for 'Shadow Tail'

All tree squirrels belong to the genus Sciurus, which comes from the Greek words "skia" (shadow) and "oura" (tail). The name reportedly reflects tree squirrels' habit of hiding in the shadow of their long, bushy tails.

8. Squirrels Were Once Rare in Many U.S. Cities

Gray squirrel in Battery Park, New York
Tree squirrels, like this one at Battery Park, were once seen as a novelty in New York City. (Photo: tovsla/Shutterstock)

In July 1856, a crowd gathered in New York's Central Park to marvel at the rare sight of a gray squirrel. Tree squirrels had been nearly eliminated from many U.S. cities by the mid-19th century, but cities responded by adding more parks and trees — and by adding squirrels. Philadelphia held one of the first documented squirrel reintroductions in 1847, followed by others in Boston, New York, and elsewhere. By the mid-1880s, Central Park was already home to about 1,500 gray squirrels.

9. American Squirrels Are Causing Trouble in Britain

Eurasian red squirrel
Eurasian red squirrels are being outcompeted in parts of the U.K. by invasive American grays. (Photo: Ashley Buttle/Flickr/CC BY 2.0)

Eastern grays are the most common U.S. tree squirrels, but in addition to helping them reclaim lost habitats, people have also introduced them to places outside their native range, from western North America to Europe and South Africa. Eastern grays are now invasive pests in the U.K., where they threaten smaller, native red squirrels (pictured above). Squirrels have also become invasive in other places around the world, including Australia, which has no native squirrels of its own.

10. Squirrels Play a Big Role in the Food Web

Squirrels are an important food source for lots of nonhuman predators, including snakes, coyotes, hawks, and owls, to name a few. They've long been hunted by people too, and once served as key ingredients for American dishes like Kentucky burgoo and Brunswick stew, although today other meats are commonly used instead.

Tree squirrels mostly eat nuts, seeds, and fruit, but they are omnivores. Gray squirrels, for example, have been known to eat insects, snails, bird eggs, and animal carcasses when other food is scarce. Like many rodents, however, squirrels can't vomit. (They also can't burp or experience heartburn.)

11. Only a Few Squirrels Hibernate

Some ground squirrels hibernate, but most squirrel species rely on caches of food to get through the winter. That could mean storing all their food in a single larder, although that's vulnerable to thieves, and some larder-hoarding ground squirrels lose up to half their cache this way. Many squirrels instead use a technique called "scatter hoarding," in which they spread their food across hundreds or thousands of hiding places, a labor-intensive hedge against theft.

Tree squirrels are even known to dig fake holes to fool onlookers, yet thanks to a detailed spatial memory and a strong sense of smell, they still recover up to 80% of their cache. Some fox squirrels also use a mnemonic strategy to organize nuts by species. And even the food these squirrels lose isn't really lost, since unrecovered nuts simply turn into new trees.

12. Some Ground Squirrels Make 'Rattlesnake Perfume'

A 2010 study found that some squirrels collect old rattlesnake skin, chew it up and then lick their fur, creating a kind of "rattlesnake perfume" that helps them hide from the smell-dependent predators.

13. Some Gray Squirrels Are All Black or White

white squirrel
A white squirrel descends a tree at a city park in Olney, Illinois. (Photo: Tony Campbell/Shutterstock.com)

If you see an all-white or all-black squirrel in North America, it's probably a gray or fox squirrel in disguise. The black variation is a result of melanism, a development of dark pigment that occurs in many animals. White fur could be caused by albinism, although many white squirrels lack the distinctive pink or red eyes, instead owing their color to leucism. Some places are more prone to white squirrels, like Brevard, North Carolina, where as many as one in three squirrels have white fur.

14. Hibernating Squirrels Could Help Protect Human Brains

Hibernating ground squirrels have a trait that could help protect stroke patients from brain damage, according to research funded by the National Institutes of Health (NIH). When squirrels hibernate, their brains experience significantly reduced blood flow, similar to what humans experience after a certain type of stroke. But squirrels wake up after hibernation with no serious effects. Scientists believe a potential drug inspired by these squirrels' adaptation "could grant the same resilience to the brains of ischemic stroke patients by mimicking the cellular changes that protect the brains of those animals," the NIH said in a news release.

15. Flying Squirrels Don't Technically Fly, but Some Can Glide the Length of a Soccer Field

red and white giant flying squirrel, Petaurista alborufus
A red-and-white giant flying squirrel surveys Foping National Nature Reserve in China. (Photo: Burrard-Lucas Photography)

Flying squirrels can't really fly — they just use flaps of skin between their limbs to glide from tree to tree — but it often seems like they can. Their acrobatic leaps often span 150 feet (45 meters), with some species covering nearly 300 feet (90 meters) in a single glide.

16. Ground Squirrels Are Overrated as Meteorologists

Marmots are celebrated as weather forecasters in the U.S. and Canada, but their skills are a bit overhyped. Punxsutawney Phil's predictions were mostly wrong between 1988 and 2010, for example, while a study of Canadian groundhogs found their success rate was only 37% over 30 to 40 years.

17. Squirrels are Talkative

Squirrels communicate using complex systems of high-frequency chirps and tail movements. Studies have also found they're capable of watching and learning from each other — especially if it relates to stealing food.

18. There's No Need to Hate Squirrels, but also No Need to Feed Them

We're lucky to have these clever, charismatic creatures living among us, but like most wild animals, the best way to appreciate squirrels is to watch them, not interact with them. Feeding wildlife is generally a bad idea, since it portrays people as a food source and could discourage natural foraging. Some squirrels can also transmit diseases to humans, and even healthy ones aren't above biting our fingers or faces.

Squirrels are notoriously feisty when food is up for grabs, as this video shows:

To be fair, however, they do share their food when there's enough to go around: