You probably see squirrels almost every day. They’re oddly familiar, right? But sometimes, they seem a bit strange too. Yes — squirrels are mammals: they’ve got fur, warm blood, and their mothers nurse live young. That one fact really shapes how they act, where they hang out, and how scientists put them into categories.
Let’s dig in. What does being a mammal actually mean for a squirrel? Scientists have some pretty specific ways to classify them, and you might be surprised by what sets tree, ground, and flying squirrels apart. There’s more to those bushy tails than you’d think.
Are Squirrels Mammals? Breaking Down the Basics
Squirrels fit into a group of animals with some clear physical and reproductive traits. Check out their fur, how they keep warm, and how they raise their babies—those are classic mammal features.
Key Mammalian Traits in Squirrels
Just look at a squirrel’s fur, their body heat, and those teeth. Squirrels have thick fur that helps them stay warm, even in the cold. Their bodies keep a steady temperature, so they’re warm-blooded like all mammals.
Their teeth? Those front incisors never stop growing, perfect for gnawing on nuts and seeds. Squirrels use a diaphragm for breathing and have a four-chambered heart, which lets them move fast and react quickly.
Female squirrels have mammary glands, and they feed their babies milk after birth. The little ones depend on that milk until they’re ready for solid food.
- Fur or hair: thick and everywhere
- Warm-blooded: steady internal temperature
- Teeth: sharp, ever-growing incisors
- Mammary glands: moms feed baby squirrels
Why Squirrels Are Classified as Mammals
Scientists put squirrels in the mammal category because they check all the boxes. Squirrels give birth to live young, not eggs. After birth, the mother nurses her pups with milk.
Squirrels belong to the family Sciuridae and the order Rodentia. That puts them in Mammalia, along with other warm-blooded, milk-making animals.
They build nests (dreys) and care for their young, which is a pretty typical mammal thing to do.
Key points:
- Live birth and milk: nursing is a must for mammals
- Taxonomy: placed in Mammalia, family Sciuridae
- Behavior: nesting and parenting fit the mammal mold
If you want to dig deeper, check out this overview of Sciuridae family traits.
Scientific Classification of Squirrels: Where Do They Belong?
Squirrels sit in a specific scientific order and family. That tells you a lot about their teeth, what they eat, and how they move. Here’s how they fit into the bigger animal picture.
Squirrels in the Animal Kingdom Hierarchy
Squirrels are animals in the kingdom Animalia. They’re part of the phylum Chordata because they have backbones.
They land in the class Mammalia, which means they’re warm-blooded, have fur, and the females feed their babies milk.
Within mammals, squirrels are in the order Rodentia. Rodents all have a single pair of upper and lower incisors that never stop growing.
That’s what makes squirrels true rodents, just like mice or beavers. But squirrels look and act differently, so you can spot them right away.
Rodents split into lots of families, but the one you want here is Sciuridae.
Sciuridae groups animals with bushy tails, sharp claws for climbing, and cheek teeth that grind seeds and nuts.
The Sciuridae Family and Squirrel Subgroups
The family Sciuridae includes tree squirrels, ground squirrels, flying squirrels, chipmunks, marmots, and prairie dogs.
Sciuridae breaks down into subfamilies like Sciurinae, Callosciurinae, and Xerinae. Each one has its own habits and lives in different regions.
Sciurinae covers many of the tree squirrels you see around, like the eastern gray squirrel and the fox squirrel (Sciurus niger).
Callosciurinae mostly includes colorful Asian tree squirrels and some giant squirrels in the Ratufa group.
Xerinae has ground-dwelling species like marmots and prairie dogs. These guys dig burrows and often live in social colonies.
Some, like the neotropical pygmy squirrel, branch off into their own little groups. Sciuridae is actually way more diverse than most people realize.
Types of Squirrels: Tree, Ground, and Flying
Tree squirrels spend most of their lives in the branches.
Species like the eastern gray squirrel and the red squirrel are good examples.
They’re great climbers.
You’ll often spot them storing nuts in bark or dirt, or nesting in tree cavities and dreys.
Ground squirrels and their relatives—think marmots, prairie dogs, chipmunks—prefer life on or under the ground.
They dig burrows and usually live in groups.
Their social behaviors differ quite a bit from those of tree squirrels.
It’s interesting to see how their habits shift depending on where they live.
Flying squirrels don’t actually fly, despite the name.
They glide through the trees using a stretchy skin membrane, the patagium, that connects their wrists to their ankles.
Most flying squirrels are nocturnal.
They use gliding to travel from tree to tree and avoid predators at night.
You’ll find two main genera worth noting: some are widespread in North America, while others are unique to Asia.
There’s a lot of variety, honestly.
From the tiny African pygmy squirrel to big marmots, squirrels come in all shapes and sizes.
You might notice how their bodies, tails, and even their personalities shift to fit their lifestyles.
If you want to dig deeper, check out this concise overview of the Sciuridae family and squirrel subgroups.
