Why Do Squirrels Spend Their Time in Trees and Chipmunks Prefer the Ground?

Over winter, chipmunks slow down and eat less in their underground bunkers. colacat/Shutterstock

At first glance, it's easy to mistake a squirrel for a chipmunk. Especially when you spot one, twitching and darting across the yard like an electrified muppet.

But given a closer look, the differences between these rodents become obvious. Chipmunks are smaller. They have stripes on their heads and much shorter tails. They even make different sounds — clucks and chirps compared to the que que que of Eastern gray squirrels.

The vague similarities make sense considering the last time these animals shared a common ancestor was around 20 million years ago. Chipmunks and squirrels — along with groundhogs and prairie dogs — are members of the same family: Sciuridae.

But millions of years is a long time to adapt physically and behaviorally to different environments. And squirrels and chipmunks, in many parts of the world, used that time to become very different critters.

One difference, however, seems to be the norm no matter where these animals are found.

Chipmunks spend most of their time on the ground, or under it. And tree squirrels prefer to live in, well, trees.

Ever wonder why that is?

A 7-year-old named Audrey did. She wrote to The Conversation recently asking the very same question.

The answer has a lot to do with how chipmunks and squirrels spend their winters. Like tiny survivalists with a paranoia streak, chipmunks winter in vast underground bunkers. Those homes, complete with camouflaged entrances, can stretch for as long as 30 feet, as LiveScience explains. And all of that space for a single occupant. That’s the kind of security a nervous chipmunk evidently needs to fall into a type of torpor.

Not to be confused with hibernation, torpor is more like extreme laziness. Before the cold season, chipmunks don't pack on the calories as some animals do. Instead, they stuff their cheeks with nuts, curl up into a little ball, reduce their body temperature and even their heart rate. That way, when they need to wake up in a snap, or get a little nippish, they can pop out even mid-winter, for a bite to eat.

A red squirrel clinging to the trunk of a tree.
For squirrels, a tree is both a home and a pantry, stocked with enough food to get them through winter. Korobcorp/Shutterstock

Tree squirrels, on the other hand, don't hibernate or fall into any other kind of torpor. Instead, as The Conversation notes, they hang out in the relative safety of trees, which also happen to double as their pantries. You may have noticed how busy tree squirrels are in the fall, scavenging every last seed and nut they can find and stocking their tree homes with enough food to get them through winter.

Although tree squirrels are awake over winter, you won't see many of them. That's because they're basically Netflixing and chilling in their cozy trees.

Chipmunks, on the other hand, are half-asleep — and barricaded below ground for the long haul.