It's time to shine the spotlight on squirrels. Jan. 21 marks Squirrel Appreciation Day, an occasion to plan some squirrel-friendly activities to celebrate the bushy-tailed creatures in your neighborhood.

Although some people may see them as a nuisance, squirrels are actually incredible creatures that are beneficial to the environment. Wildlife rehabilitation specialist Christy Hargrove started National Squirrel Appreciation Day in Asheville, North Carolina in 2001, National Today said. The idea was to encourage people to show kindness toward the creatures.

You can celebrate the day by leaving out nuts for your local squirrels, dressing up your pets as squirrels or simply by watching some amusing squirrel videos.

On this year's National Squirrel Appreciation Day, let's have a look at some interesting facts about the rodents, courtesy National Today, Britannica and National Wildlife Federation (NWF):

Their front teeth don't stop growing

One of the things that make squirrels so adorable is their cute front teeth. According to the NWF, those tiny teeth don't actually stop growing, just like in other rodents such as mice, hamsters, gerbils and beavers.

The rodents' incisors also don't have roots. To prevent their teeth from growing into their brains, they gnaw and grind their teeth on hard objects to keep them short and sharp, Michigan State University explained.

Squirrels are forgetful thieves

Squirrels like to bury their precious nuts, dig them up and rebury them again so that other nut-loving squirrels can't easily steal their stash. This is because squirrels can lose up to 25% of their nuts to thieves. Sometimes, squirrels may even pretend to dig a hole but they won't deposit the nut there at all. This is to confuse possible thieves, the NWF said.

However, this can lead to other problems because squirrels tend to forget where they have buried their stash. In the end, they don't get to recover some 74% of the nuts they bury. Instead, they completely leave some of the buried nuts in the ground itself and end up getting other squirrels' nuts.

Thanks to their forgetfulness, many of the nuts that they buried (and did not get stolen) will germinate in the soil and grow into trees. This way, squirrels have "accidentally" added countless trees to forests.

Squirrels can also be fierce

Yes, squirrels are cute and they can be kept as pets. But the furry creatures can also be rather fierce.

Although most tree squirrels eat hard nuts, fruits, insects and sometimes nectar and bird eggs, there are some in the Sciurus species that can kill and eat other animals, including mice, rabbits, adult birds and even other squirrels.

This behavior, however, is considered rare.

Squirrels are good treasure hunters

Squirrels are actually quite good when it comes to hunting for buried food, especially in the winter when food is scarce. Some squirrel species are capable of smelling food that's buried even under a foot of snow.

Humans brought them to cities

There are many people who see squirrels as a nuisance in our cities and neighborhoods. But did you know that humans were actually the ones who brought squirrels to the cities?

Squirrels were not present in cities in the U.S. until the mid-19th century. In 1847, squirrels were introduced to Philadelphia's Franklin Square. Several years later, they were brought to Boston and New Haven and other parts. Now, these creatures are a natural part of the cities.

In this photo, a red squirrel stocks up on nuts in Queen Elizabeth Forest in Aberfoyle, Scotland on November 8, 2017. Getty Images / Jeff J Mitchell