You probably see squirrels every day and wonder if they really belong here. Yep—most squirrel species you spot in North America are native, with a surprisingly deep fossil history on this continent. Some populations, though, got moved around by people. That mix of old lineages and human introductions? It explains why their numbers and types can look so different depending on where you are.
Let’s dig into which species are the true locals, which ones people introduced, and why fossils and current ranges actually matter. You’ll see some clear examples and maybe a few facts you didn’t expect—squirrels in North America have a wilder story than you’d think.
Are Squirrels Native to North America?
Squirrels are part of the rodent family Sciuridae, and their story in North America goes way, way back. Their ancestors showed up here early, and native species changed over time to fit into forests and grasslands.
Ancient Origins and Migration
Fossils tell us that squirrel-like animals already lived in North America by the Late Eocene, which was about 40–35 million years ago. These fossils include early versions of flying squirrels and primitive tree squirrels.
Scientists rely on those fossils to show that the Sciuridae family got established here early on. You’ll also find related fossils in Eurasia and Africa, so squirrels didn’t just pop up in one place.
Still, a bunch of modern squirrel species seem to have branched out from North America, so a lot of today’s squirrels trace their roots to populations that lived and evolved right here.
Those key fossils and the family’s wide modern range make it clear—North America played a huge role in early squirrel evolution. That’s why you see so many kinds of squirrels here today: tree squirrels, ground squirrels, and flying squirrels all call North America home.
When and How Squirrels Arrived in North America
Squirrel ancestors already lived in North America by the Late Eocene. Over millions of years, they split into different groups and spread out.
Land bridges, like the Bering Land Bridge, let some squirrel lineages move between Asia and North America. Not all modern North American squirrels arrived at the same time, though.
Some lineages seem to have started on this continent and stayed, while others came over later from Eurasia. People also moved a few species around more recently—like when eastern gray squirrels ended up in new regions thanks to humans.
If you want to figure out when certain squirrels showed up here, you have to look at fossils, anatomy, and genetic data together. Those clues help build a pretty good timeline.
Adaptation and Evolution on the Continent
Once squirrels got here, they adapted to all sorts of habitats. Tree squirrels picked up strong claws and those long tails for balance.
Ground squirrels started burrowing and living in social colonies. Flying squirrels developed gliding membranes (patagia) so they could move between trees at night.
You’ll notice this variety in the native species list: eastern gray and fox squirrels in forests and cities, chipmunks and ground squirrels in grasslands, and several flying squirrel species in wooded spots.
Climate, predators, and food sources shaped their body size, fur, and even how they stash food or raise babies. These changes let squirrels thrive everywhere—from deserts and temperate forests to suburban backyards.
The Sciuridae family’s diversity in North America really shows how evolution created so many species for different niches.
Native and Notable Squirrel Species Across North America
You’ll find tree squirrels in parks and backyards, ground squirrels and marmots in open fields and rocky hills, and flying squirrels gliding between trees using those skin flaps. Each species has its own range, favorite habitat, and quirks that shape how you see them.
Tree Squirrels: Gray, Fox, and Red Squirrels
The eastern gray squirrel (Sciurus carolinensis) is super common in eastern forests and most cities. You’ll recognize it by its medium size and bushy gray tail.
It nests in tree cavities or leafy dreys and stashes nuts in the ground and trees for winter. The fox squirrel (Sciurus niger) is bigger and often orange-brown, hanging out in open woods and suburbs.
You’ll spot it foraging on the ground and using tree cavities or old bird nests for shelter. The American red squirrel (Tamiasciurus hudsonicus) is smaller and fiercely defends its territory in conifer forests.
You’ll hear its sharp calls and see piles of cones near its midden. In the West, look for the western gray squirrel and Douglas squirrel. Abert’s squirrel (Sciurus aberti) loves ponderosa pine and has those tufted ears. Each of these tree squirrels sticks to certain forests.
Ground Squirrels, Marmots, and Prairie Dogs
Ground squirrels dig burrows and live in open habitats, so you can watch them from a distance. California ground squirrel and Franklin’s ground squirrel are common ground-foragers.
Their burrows give them shelter and a place to raise their young. Marmots—those bigger, alpine species—hang out on rocky slopes and meadows.
You’ll see them sunning on rocks and calling out alarms. They hibernate through long winters and build up fat to survive.
Prairie dogs live in big colonies called towns. You’ll hear their complicated alarm calls and see their burrow openings scattered across grasslands.
Their social lives and tunnel engineering totally shape prairie ecosystems and even change how people use those lands.
Flying Squirrels and Other Unique Species
Flying squirrels don’t actually fly, but they glide around with the help of a flap of skin stretched between their legs. The northern flying squirrel spends its nights awake, living in older forests where it can find tree cavities.
Honestly, you probably won’t spot one very often. Still, you might come across its nests tucked away in those cavities or maybe even in an old woodpecker hole.
Chipmunks, with their stripes, scurry along the ground and through brush. They stuff seeds into their cheek pouches and dig shallow burrows.
Tree cavities and snag trees really make a difference for a lot of these animals. They use them for nesting, shelter, or raising their young—nature’s own apartment complex, if you think about it.
