Squirrels get lots of attention from humans, but not always much appreciation. We tend to dwell on the stolen birdseed or the occupied attics, yet squirrels have a long, mostly harmless — and often entertaining — history of 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 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.

That's the idea behind Squirrel Appreciation Day, founded in 2001 by North Carolina wildlife rehabilitator Christy McKeown. It's held Jan. 21 every year, but much like Elephant Appreciation Day, Penguin Awareness Day and similar informal animal holidays, it's pretty decentralized. As McKeown explains on her website, "while there are no official events scheduled, you can help celebrate by putting out extra food for the squirrels." She also warns, though, that "too many treats will lead to health problems." (And routinely feeding any wild animal could make it dependent.)

That holiday is mainly focused on bushy-tailed tree squirrels common in the Eastern U.S., and it's held in midwinter since that can be a fallow time of year for them. But across much of North America, and elsewhere, squirrels of all kinds play important ecological roles year-round. So, to help every day feel more like Squirrel Appreciation Day, here are a few interesting facts about these intriguing rodents:

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

1. There are more than 200 squirrel species worldwide, from tree squirrels and flying squirrels to chipmunks and marmots. They're all in the Sciuridae family, which is native to every continent except Australia and Antarctica.

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

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

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

3. Squirrels have four front teeth that grow continuously, at a rate of about six inches per year. This helps their incisors endure the constant gnawing.

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 National Security Agency, in 2015. (Photo: Ztudio-Neosiam/Shutterstock)

4. 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. 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."

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

6. 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 wide, 250 miles long and contained an estimated 400 million individuals.

7. 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.

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)

8. 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.

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

9. 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). This has raised the popularity of eating gray squirrels among some Britons, part of a broader global trend in eating invasive species.

10. There's a rich history of eating squirrels in the U.S., too, where they've long been used in dishes like Kentucky burgoo and Brunswick stew. Squirrel meat has fallen out of favor in recent decades, especially that of flying squirrels, but many Americans still hunt and eat eastern grays. Squirrels are also an important food source for lots of nonhuman predators, including snakes, coyotes, hawks and owls.

11. 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.

12. Better hope those carcasses aren't too rancid, though — squirrels, like many rodents, can't vomit. (They also can't burp or experience heartburn.)

fox squirrel raiding a birdfeeder A fox squirrel, the largest species of North American tree squirrel, finds food in California. (Photo: Franco Folini/Flickr)

13. The average adult squirrel needs about a pound of food per week.

14. Tree squirrels don't hibernate in winter, instead relying on caches of acorns and other nuts they buried earlier in the year. Gray squirrels protect these caches with some impressive anti-theft precautions, like digging fake holes to deceive onlookers or digging up and reburying their food multiple times. They may create hundreds of caches per year, but thanks to a detailed spatial memory and a strong sense of smell, they recover about 40 to 80 percent. And the ones they lose aren't really lost, since unrecovered acorn caches simply turn into new oak trees.

15. 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.

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

16. 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.

17. An eastern gray "rally squirrel" became an impromptu mascot for Major League Baseball's St. Louis Cardinals when it ran onto the field during the 2011 playoffs. The Cardinals went on to win the World Series.

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)

18. 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, with some species covering nearly 300 feet in a single glide.

American red squirrel An American red squirrel pauses on a pine tree in Oneida, Wisconsin. (Photo: wplynn/Flickr)

19. American red squirrels are solitary and highly territorial, but in some rare cases they've been known to adopt orphaned pups of their relatives.

20. Marmots are celebrated as weather forecasters in the U.S. and Canada, but their skills are a bit over-hyped. 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 percent over 30 to 40 years.

21. 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.

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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 can share food when there's enough to go around:

Editor's note: This article has been updated since it was first published in January 2012.