Are Squirrels Native to North America? The Full Story in 5 Species

Yes, squirrels are native to North America, and the continent is one of the group's two great evolutionary cradles. Every squirrel on the continent today — all 60-plus species — traces its ancestry to a single squirrel lineage that crossed from Asia over a land bridge roughly 40 million years ago. That ancestor then split into the three North American squirrel groups: tree squirrels, ground squirrels, and the flying squirrels. In plain terms: the squirrel on your bird feeder is a genuine native, not an import, even though a few famous city squirrels came from Europe.

How Squirrels Reached North America

The squirrel family, Sciuridae, originated in what is now Asia roughly 50 million years ago. North America had no squirrels at all during the early Eocene. The door opened when Asia and North America connected across Beringia, the intermittent land bridge where the Bering Strait now sits.

Squirrels crossed in multiple waves, not one. The first tree squirrels appear in the North American fossil record around 40 million years ago. Ground squirrels and flying squirrels arrived in separate later waves. Each wave then diversified in isolation, which is why North America ended up with so many distinct forms.

The mechanism is known as allopatric radiation. A small founding population crosses into new territory, then splits into separate lineages as glaciers and mountain ranges cut the continent into isolated pockets. The Pleistocene ice ages, from about 2.6 million to 11,700 years ago, repeatedly carved and reconnected those pockets. That push-and-pull is the main engine behind North America's squirrel diversity today.

Genetic studies (notably those of Herron, Waterman, and colleagues in the 2000s) confirm the crossing order. Flying squirrels sit closest to the first Asian arrivals. Ground squirrels and tree squirrels split into their own North American clades later.

A Timeline of Squirrel Arrival and Radiation

The time course matters because "native" is a question about ancestry, not about how long a species has been in one spot. The table below shows the deep timeline, with the most important signal in the last row.

One caveat: the deep dates in the top rows are estimates from molecular clocks and fragmentary fossils. The crossing order is well supported. The exact millions of years carry uncertainty of several million either way. The 1600s row is the one to remember when the "native" question gets tangled with city squirrels.

The Three North American Groups, With Numbers

North America holds roughly 65 native squirrel species across three body plans. Each group solves the same survival problems in a different way, and the numbers show how.

Tree squirrels are the climbers. They include the eastern gray squirrel (Sciurus carolinensis), the western gray, the fox squirrel, and the red squirrel. Eastern grays run 15 to 20 inches long including the tail and weigh 14 to 21 ounces. Their tails make up 40 to 50 percent of total length, a balance organ for leaping between branches. Tree squirrels cache thousands of nuts each fall, and they recover a meaningful share of them — scatter-hoarding research puts recovery at roughly 70 to 95 percent for nearby caches. The rest grow into oaks and hickories. In plain terms: the squirrel forgets, and the forest plants itself.

Ground squirrels live at or below ground level and are the most numerous group by species count. The thirteen-lined ground squirrel, the California ground squirrel, and the Arctic ground squirrel all belong here. Arctic ground squirrels endure core body temperatures that drop to about 27 degrees Fahrenheit in hibernation, among the deepest known for any mammal. Ground squirrels range 7 to 15 inches long and 4 to 16 ounces depending on species.

Flying squirrels are the nighttime gliders. North America has three native species, including the northern flying squirrel and the southern flying squirrel. They do not fly — a furred membrane called the patagium stretches between wrist and ankle and lets them glide 20 to 150 feet, with a glide ratio around 2 to 3 feet forward for every foot of drop. Northern flying squirrels weigh 2 to 5 ounces; southerns 1.5 to 3 ounces.

Every species above is native. The species count is the strongest single signal that squirrels radiated here rather than arrived.

Native Versus Introduced: Where Confusion Comes From

The most common misconception is that city squirrels are imports. They are not. Eastern gray squirrels, fox squirrels, and American red squirrels are all native, even in downtown parks where they seem invasive.

The confusion has a real seed. European red squirrels (Sciurus vulgaris) were released into a handful of North American cities in the 1800s by homesick settlers and acclimatization societies. Those introductions mostly failed. A larger wave of introduced squirrels came to places outside their native range — eastern grays shipped to Britain and Italy, where they now outcompete the native European red. That European story gets retold as if it happened here.

The table below separates what people often believe from the record.

There is a legitimate edge case. A California ground squirrel in Ohio or an eastern gray in California would be out of range, whether moved by people or by climate. Range expansion and range shift are natural; a squirrel thousands of miles from its native region is not.

Why North America Is a Squirrel Hotspot

North America is native squirrel country on a scale few regions match. The continent holds about 20 percent of the world's roughly 300 squirrel species. Eurasia holds most of the rest.

Three factors explain the density. First, the continent's mountain chains and glacial history created island-like habitats that favored speciation. Second, the deciduous and mixed forests of the East and the conifer forests of the West offered huge expanses of food. Third, the squirrel body plan is flexible: a tree form, a ground form, and a gliding form can all live in the same forest and split the food supply by height and by hour. Tree squirrels work the canopy by day; flying squirrels work it by night; ground squirrels work the floor and the soil.

The mechanism is niche partitioning, and the numbers make it concrete. In a single eastern forest, you can find eastern gray squirrels, southern flying squirrels, and eastern chipmunks — all three native, all three eating nuts, none of them competing head-on because they feed at different heights and times.

Misconceptions and Edge Cases Worth Knowing

Not every squirrel in North America is a full native in the strictest sense. The eastern fox squirrel (Sciurus niger) has been introduced well outside its native range in parts of the West and Northeast, usually by people. The species is native to the continent, but a fox squirrel in Washington state is not native to that state. The distinction matters for conservation planning.

A second edge case is the eastern gray squirrel in Europe. The species is native to North America and a serious invader in Britain, where it has driven the native European red squirrel into a fraction of its former range since the 1870s. The same animal can be a native in one place and an invasive in another. Location, not species identity, decides.

A third caveat is the fossil record's gaps. The oldest North American squirrel fossils are teeth and jaw fragments, not full skeletons. Reconstructing the exact arrival date is an estimate, not a fixed number. Scientists agree on the direction and rough timing; they debate the precise millions of years.

What to Actually Do With This

Understanding native status changes how you handle the squirrels around you.

• Do not treat an eastern gray or fox squirrel in its native range as invasive. It is not; control efforts should focus on protecting structures, not on removal.
• Check your state's native range map before calling an animal a pest. A squirrel outside its native range may be a genuine introduction.
• Protect cavities and dead trees where possible. Flying squirrels and many cavity-nesting squirrels depend on them, and snag removal is a leading cause of local decline.
• Leave exclosures and baffles on feeders as the first line of defense. Native status and nuisance are separate questions.
• Report unusual squirrel sightings to your state wildlife agency, especially species far outside their range.
• Avoid feeding wildlife directly, which can concentrate squirrels, spread disease, and cause the overabundance that fuels the "pest" label in the first place.

In plain terms: the squirrel is a native, and the practical job is to live alongside it, not to root it out.

Limits of What We Know

Native status is well established for the major species. The deep timeline, though, rests on fragmentary fossils and molecular clocks, and those dates shift as new methods appear. The species count itself is a moving target: taxonomists split and merge squirrel species regularly, so "about 65" is a working figure rather than a fixed total.

The more useful limit is a practical one. Knowing that squirrels are native tells you where they belong in evolutionary terms. It does not tell you how many a given park can support, or when a native population has become locally overabundant. Those are management questions answered by local data, and they are where the real uncertainty lives.