At this very moment, squirrels throughout the northern hemisphere are busy getting fat and fluffy for the winter. But these industrious animals do more than gorge themselves.

Their social structures, memories, and critical thinking skills are complex, yet seeing a squirrel in action often requires little more than stepping into a public park or backyard. That’s because squirrels are found in nearly every habitable region of the world, except Australia. There are 287 different species.

Independent, and usually docile (except for this one that attacked five people in Brooklyn), squirrels exhibit a wide range of fascinating behavior. Explore some common squirrel behaviors below; then watch the video above to see them in action.

They Have an Impressive Nut Stash

To prepare for the winter, squirrels spend a lot of time doing what's known as "caching."

"If people want to see them caching, now is a good time," said Suzanne MacDonald a York University professor who studies the cognitive functions that motivate foraging behaviors. Though she's studied rarer animals like cheetahs and elephants, MacDonald also has a strong interest in our urban neighbors like raccoons and squirrels. She explained that fall is a busy time for many species of squirrels as they prepare for a less hospitable winter.

"You'll see them collecting stuff and running and frantically digging," she said.

This caching behavior isn't as random as it might seem. One study, recently published in the journal Royal Society Open Science, showed that squirrels organize their nuts more carefully than many people organize their closets.

From observing fox squirrels, a species found throughout the eastern half of North America, researchers from the University of Berkeley found that the rodents organized their nut stash by quality, variety, and possibly even preference. The arrangement is referred to by researchers as "chunking."

“Squirrels may use chunking the same way you put away your groceries," the study's senior author, Lucia Jacobs, said in a UC Berkeley press release. "You might put fruit on one shelf and vegetables on another. Then, when you’re looking for an onion, you only have to look in one place, not every shelf in the kitchen.”

They Zig Zag to Avoid Predators

Like a kid evading a dodge ball, squirrels will dart back and forth to confound a predator. When faced with a replica figure of a squirrel, they approach with apprehension. Clearly, they want the food around it, noted MacDonald, but squirrels have many natural predators, which makes them skittish.

With a mix of curiosity and social anxiety (people aren't alone in that), squirrels approach objects that strike their interest or promise food. But living near the bottom of the food chain has imbued them with a keen sense of their surroundings. As MacDonald puts it: "They should be skittish because they can be eaten by everything."

In the event that they are confronted with a predator, squirrels will dart from side to side while running away, until they can find a tree to climb to safety.

Sadly, this is also why many squirrels get hit by cars. When trying to cross the street, squirrels alarmed at the sudden onset of a car will begin to dart back and forth in a lane, which can put them in a deadly path.

They Have Noticeable Body Language

A squirrel that flicks its tail in snappy, arced movements is likely frustrated and showing a reactionary emotion akin to someone stomping their foot in frustration. To understand this behavior even better, a 2016 study published in the Journal of Comparative Psychology tested how the animals react to obstacles.

Researchers tracked 22 fox squirrels that were trained to open a small box containing walnuts, a squirrel delicacy. After a squirrel had mastered the box, researchers then put it through another series of tests, in which the box was locked or empty. The more frustrated squirrels became, the more actively they moved their bushy tails.

Squirrels presented with frustrating boxes didn't only show signs of annoyance, but they also persisted in trying to obtain their coveted walnuts and tried several problem-solving strategies.

Tails aren't just used by squirrels venting their exasperation. In contrast to the quick, darting flicks, squirrels also whip their tails in longer, more flaglike movements. MacDonald says this is likely to signal to other squirrels that a predator is in the vicinity. Often, the movements are used in conjunction with three types of calls—quick, chirping clicks, a longer "waaa" type of sound, and lower pitched tonal whistles.

Research published in 2014 in the journal Behavior observed that these different calls were used in tandem with various types of tail flicks to give specific signals. The researchers found that some sounds and tail movements were closely associated with predators that approached on the ground versus from the sky.

They're Curious

Armed with a small camera and a piece of bread, lawyer David Freiheit had his 15 minutes of Internet fame in 2014 after he laid a makeshift camera trap for a gray squirrel in his neighborhood in Canada.

Apprehensive at first, the squirrel closeup shows the animal checking out the camera, before it eventually decides to grab it and run it up a tree. Eventually, the squirrel drops the camera to the ground, but not before viewers get the chance to experience the animal's unique point of view.

Watching the video, MacDonald was not surprised, saying squirrels love oddities, especially when they're baited with food.

"We usually think rats are really smart," she said. "And we should assume that squirrels are also smart because they're rodents, too."