You probably picture squirrels as those quick, jittery animals darting from branch to branch. But what really makes a squirrel a squirrel? A squirrel is a small to medium-sized rodent in the family Sciuridae. That includes tree squirrels, ground squirrels, chipmunks, marmots, prairie dogs, and flying squirrels. This covers why they all have those sharp teeth, strong back legs, and that unmistakable bushy tail.
If you stick around, you’ll see how scientists group squirrels, why their tails matter, and just how many types pop up around the world. You’ll get the basics, the main types you might spot in your local park or forest, and a few easy facts to help you tell them apart.
Definition of Squirrel
Squirrels are small, bushy-tailed rodents you’ll often spot in trees, parks, or even your backyard. They’re part of a bigger rodent family and show off habits like stashing food and climbing with surprising skill.
Scientific Classification and Squirrel Family
Scientists put squirrels in the family Sciuridae. This group includes tree squirrels, ground squirrels, chipmunks, marmots, and flying squirrels. The genus Sciurus covers many of the tree squirrels you know, like the red squirrel and gray squirrel.
When folks talk about the tree-dwelling types, they’ll sometimes use the term sciurine. Since squirrels are rodents, they’ve got those ever-growing incisors for gnawing. Sciuridae has about 268 species spread across nearly 50 genera. Some squirrels stick to the ground, while others live in trees or even glide between them.
Knowing this makes it easier to tell a tree squirrel from a ground or flying squirrel.
Physical Characteristics: Bushy Tail, Fur, and Size
The bushy tail really stands out first. Squirrels use it for balance when running along branches, and it can work as a blanket when things get chilly. Their fur comes in shades of gray, brown, red, or even black, depending on the species and where they live.
Squirrels come in all sizes—from tiny pygmy squirrels under 10 cm to bigger species that weigh a few kilos. They’ve got sharp claws and strong hind legs for jumping and climbing. Their eyes sit high up, giving them a wide view to spot predators before it’s too late.
Squirrel as a Verb: Squirrel Away and Hoarding
When you hear someone say they “squirrel away” food or money, it means they’re hiding it for later. That phrase comes straight from what squirrels actually do—hoarding nuts and seeds in little stashes called caches.
Some squirrels scatter their stashes all over the place (scatter-hoarding), while others keep everything in one spot (larder-hoarding). Scatter-hoarding helps them spread out the risk and, funny enough, helps forests too since some seeds get forgotten and grow into new trees.
You’ll see different forms of the phrase, like “squirreled away” or the British “squirrelled.” Both just mean something’s been tucked away.
Want to dig deeper? Check out Britannica for more about the squirrel family or Merriam-Webster for dictionary definitions.
Major Types and Diversity of Squirrels
Squirrels cover a lot of ground, from tiny tree-dwellers to big burrowers. Their body shape, tails, feet, and habits all fit the places they call home and what they like to eat.
Tree Squirrels and Arboreal Adaptations
Tree squirrels mostly stick to the trees. You’ll spot them by their long, bushy tails and sharp claws. Their back ankles can twist around so they climb down trunks headfirst.
Strong incisors let them crack open nuts and seeds. Many have thick fur and long tails that help them balance, especially on those skinny branches. The tail also acts like a steering wheel when they leap.
Some tree squirrels, like the African pygmy squirrel, are tiny. Others, such as the Oriental giant squirrels in Southeast Asia, are huge by comparison. Flying squirrels also live in trees, but they glide using a skin flap stretched between their legs.
Look for their nests—called dreys—made of leaves or tucked into tree hollows.
Ground Squirrels, Chipmunks, and Marmots
Ground squirrels hang out on or under the ground. They dig burrows you’ll see as mounds and tunnels. Prairie dogs and marmots (yep, including woodchucks) fit in here and usually live in groups.
Chipmunks are smaller ground squirrels. They store food in their cheek pouches and dart quickly from place to place. These species have shorter, less bushy tails and strong front legs for digging.
Many ground squirrels hibernate or slow down in winter. Their burrows give them a spot to nest, stash food, and hide from predators. Some stand up tall to watch for danger and use loud calls to warn their buddies.
Notable Species: Red Squirrel, Grey Squirrel, and More
Red squirrels (Tamiasciurus and some Sciurus species) are smaller and often pretty territorial. You’ll find them guarding food stashes and nests, especially in pine forests.
Gray squirrels (Sciurus carolinensis) seem to thrive in towns, parks, and suburbs. They’ll eat nuts, seeds, fruit, and sometimes even bird eggs.
Other interesting types include the tiny pygmy squirrels and the big Oriental giant squirrels. Flying squirrels, mostly active at night, help spread seeds around. Marmots and prairie dogs shape grasslands by digging and grazing.
Every species has its own quirks—how it eats, where it nests, how social it is, and when it’s most active.
Global Distribution and Habitat
Squirrels live all over the Americas, Europe, Asia, and Africa. You just won’t find them naturally in Australia, New Guinea, or Madagascar.
Tree squirrels go for forests, from the cold boreal zones in Canada right down to the lush rainforests in South America.
Ground squirrels stick to grasslands, deserts, and alpine meadows. You’ll spot prairie dogs out on North American plains, while marmots hang out in the mountains.
Flying squirrels spend their nights gliding through forest canopies, moving from tree to tree. In cities, grey squirrels often make their homes in attics or settle into park trees.
When people clear forests or introduce new species, local squirrel populations can really change. So, depending on where you are, you might notice a different mix of tree, ground, or flying squirrels.
Links for further reading: see the detailed family overview at Britannica and the species listing at Animal Diversity Web.
