If you live in the United States, you’re probably surrounded by these little gray rodents. But how much do you really know about the creatures frolicking through your backyard?

1. Squirrels can be trained.

When filming Willy Wonka and the Chocolate Factory, Tim Burton wanted his squirrel scene to be as realistic as possible. As a result, he used live animals instead of CGI and brought in animal trainer Steve Vedmore to wrangle the squirrels. It took about 10 months to train and film the animals in action. With an acorn reward system, the trainer was able to transform the squirrels into tiny, furry actors.

Of course, there were some difficulties. "You are sometimes asked to do the almost impossible," Vedmore said. "The assistant director wanted us to keep a squirrel perfectly still at one point—but they don't do that. They are constantly looking around and searching.

2. They’re sneaky when hiding their nuts …

Squirrels are secretive, deceptive, and suspicious when it comes to their precious trove of acorns. The animals are wary when burying their food, and will sometimes only pretend to hide it if they suspect they are being watched. The paranoid hoarders will dig up and re-hide their snacks several times in an effort to throw off potential thieves.

The clever rodents are also discerning in what acorns they eat versus what they bury. Red-oak acorns are high in fat and sprout late, so they make ideal candidates for winter storage. White-oak acorns are less nutritious and germinate sooner, so those are often consumed immediately.

3. … And they usually find them

It has long been believed that squirrels forget their hiding places and are forced to rely on smell to retrieve them. Any acorns still lost would have the chance to grow into trees. This misconception was tested in a 1990 study at Princeton University. Researchers allowed squirrels to hide hazelnuts in an outdoor area. After several days, the animals were released to find their nuts, as well as the hidden acorns of others. The subjects were considerably more capable of finding their own nuts, which showed that while squirrels can find food through odor, memory is a more effective method. [PDF]

The video above shows a potentially more convincing test: Despite the acorn being well within smelling range, the squirrel test subject continuously chooses the empty cup where the acorn used to be.

4. Relatives will raise orphan squirrels .

Squirrels have been observed engaging in altruistic behavior and will sometimes adopt a squirrel pup in need. Through observation and DNA analysis, scientists have discovered that squirrels will sometimes have babies in their nest that are not their own. Despite being solitary creatures, squirrels will raise orphaned babies if they can determine that the pup is closely related.

5. Bob Ross had one as a pet.

Bob Ross loved animals and even had a pet squirrel named Peapod. The tiny animal would occasionally accompany Ross on set.

6. You can’t sneak up on them.

Squirrels’ eyesight is okay—they can see about as well as a person with red-green colorblindness. Their real talent is that their peripheral vision is just as good as their focal vision. That means they don’t need to turn their heads to see what’s going on around them. The animals also see the world through pale yellow lenses, which help cut down on glare.

7. Cats have nothing on squirrels.

You may think cats are good at landing on their feet, but squirrels can fall from dizzying heights without a scratch on them. They are arboreal creatures, meaning they spend the majority of their time up in the trees. What goes up must come down, and the little animals have developed a special way to survive falling out of a tree, in case they misjudge the strength of a branch. By spreading out their bodies and puffing their tails, squirrels can catch more air and slow down their fall.

As if that wasn't enough, squirrels can also purr. After a baby squirrel fell out of its nest in Mississippi, a kindly cat adopted it. The little impostor learned how to purr just like a kitten.

8. Their tail wagging sends a message.

Squirrels use their bushy tails for a variety of reasons. The built-in blanket keeps them warm in the winter, and provides shade in the summer. Tails also work as an effective means of communication: if you see a squirrel sitting still but wagging their tail, they’re sending a message. The general gist is: "Stay away!" When upset or wary of predators, the tail works to warn others in the area of danger. It’s also used as a territorial warning to keep other squirrels away from their precious acorn supply.

9. Squirrels can live to see their 20th birthdays.

Squirrels live a long time. In the wild, their lifespan is about 12 years (assuming nothing eats them). In captivity, they can survive to be 20 years old. In comparison, eastern chipmunks can live to be eight, but most don’t make it past their third birthday.

10. Meat is (occasionally) on the menu.

Many view the squirrel as an adorable herbivore that lives on a steady diet of acorns. In truth, squirrels are omnivores and will eat meat as it becomes available. In the spring and summer, squirrels will incorporate insects and stolen eggs into their diet. The scavengers will also occasionally eat road kill or dead birds they come across. In the winter, ice will sometimes prevent squirrels from reaching their cache of acorns, so who could blame them for getting a little creative?

11. They make nests

Squirrels are known for their dens in tree cavities, but sometimes they take a page from the birds’ handbook and build a nest. The clumpy looking nests are made with twigs, leaves, and moss. Sometimes, they'll add some flair with paper or candy wrappers. The inside is lined with soft grass and leaves to cushion their babies.

Despite their appearance, squirrel nests are actually quite sturdy. “From the ground, most leaf nests look small and flimsy, although a closer examination shows that they are by no means so frail as they appear,” says biologist Durward Allen. “On several occasions after a rain I evicted a squirrel and found its nest to be dry and warm.”

BONUS: You can send your friend a squirrel-gram.

If you have a friend about to turn 21, then you might want to warn them about the dangers of alcohol. Luckily Penn State has created an adorable PSA featuring squirrels in birthday hats. You can find the cautionary birthday e-card here (warning: there’s sound).