The family Sciuridae includes all squirrels, chipmunks, and marmots. This diverse group of rodents has adapted to nearly every terrestrial environment, from tropical rainforests to deserts and high-altitude tundras. The term “squirrel” encompasses over 280 species whose lifestyles can be dramatically different depending on where they make their home.
The Global Reach of the Squirrel Family
Squirrels are native to the Americas, Eurasia, and Africa, establishing a near-global distribution. They thrive across the Northern and Southern Hemispheres, extending from the boreal forests of Canada and Siberia down to the temperate woodlands and equatorial jungles of South America and Southeast Asia.
There are a few significant geographical exceptions where squirrels are naturally absent. The family Sciuridae did not evolve natively in Australia, Antarctica, or the island of Madagascar. They are also absent from the most extreme polar regions and the driest central deserts, such as the Sahara, where resources are too sparse to support a permanent population.
Tree Squirrels and Their Forest Habitats
The classic image of a squirrel typically refers to the arboreal tree squirrels, which are distributed throughout the world’s forests. In the New World, species like the Eastern Gray Squirrel (Sciurus carolinensis) and the Fox Squirrel (Sciurus niger) are common in the deciduous and mixed woodlands of North America, where they rely heavily on mast-producing trees like oaks and hickories.
These squirrels are active during the day, constructing nests, called dreys, from leaves and twigs high in the canopy, or utilizing natural tree cavities for shelter. Their range extends southward into the tropical rainforests of South America, and northward into the coniferous boreal forests where the American Red Squirrel (Tamiasciurus hudsonicus) resides. In Eurasia, the European Red Squirrel (Sciurus vulgaris) occupies similar temperate and coniferous habitats.
Tropical forests, particularly in Asia, host some of the largest species, such as the Oriental Giant Squirrels (Ratufa), which primarily live high in the forest canopy and rarely descend to the ground.
Ground Squirrels in Open and Specialized Environments
Ground squirrels, which include chipmunks, marmots, and prairie dogs, have evolved to inhabit non-forested biomes, living primarily in burrows they excavate themselves. Their habitats are incredibly varied, spanning grasslands, rocky deserts, and high-altitude mountain ranges across the globe. These species tend to be more robust than their arboreal relatives, possessing shorter, sturdier forelimbs adapted for digging.
In North America, the grasslands are home to Black-tailed Prairie Dogs (Cynomys ludovicianus), which live in highly social colonies and maintain extensive, complex tunnel systems. Higher elevations and northern latitudes host the large, stout-bodied marmots (Marmota), which can be found in mountain ranges across North America and Eurasia, including Himalayan marmots at elevations exceeding 16,000 feet.
Chipmunks, such as the Siberian Chipmunk (Eutamias sibiricus), are smaller and often occupy scrublands or the edges of forests, where they use burrows for nesting and to escape predators. African ground squirrels (Xerus) inhabit savannas and rocky deserts, using their tails as a parasol to shade themselves in arid environments. Antelope Ground Squirrels (Ammospermophilus) are year-round active desert dwellers in the southwestern United States and Mexico, who regulate their body temperature by cycling between hot surface foraging and cool burrow retreats.
Flying Squirrels and Nocturnal Niches
Flying squirrels represent a specialized group occupying a nocturnal niche within forested habitats. Their distribution is defined by their gliding ability, which relies on a furred membrane called the patagium that stretches between their wrists and ankles. This adaptation allows them to glide significant distances between trees, moving through the forest canopy at night.
The two North American species, the Northern Flying Squirrel (Glaucomys sabrinus) and the Southern Flying Squirrel (Glaucomys volans), are found in coniferous, deciduous, and mixed forests, often utilizing tree cavities created by woodpeckers or wood rot for nesting. Asia holds the greatest diversity of these specialized rodents, with numerous species, including the giant flying squirrels (Petaurista), distributed across forest ecosystems from Pakistan to Japan and the Indonesian islands.