Arizona is home to a surprising array of squirrel species, a diversity made possible by the state’s extreme variation in elevation and climate. From the Sonoran Desert lowlands to the high-altitude forests of the Mogollon Rim, distinct habitats support specialized populations of these rodents. The presence of both arid, rocky environments and lush, high-elevation pine forests creates unique ecological niches for different squirrel types. This geographic tapestry ensures that the squirrel family, Sciuridae, is well represented across the state.
Arizona’s Squirrel Diversity
The family Sciuridae includes all squirrels, which are broadly grouped by their primary lifestyle: tree squirrels, ground squirrels, and flying squirrels. In Arizona, the most commonly encountered species fall into the first two ecological categories, each adapted to survive in vastly different biomes. Tree squirrels typically inhabit the deciduous and conifer forests found at the state’s higher elevations and along riparian corridors.
Ground squirrels, by contrast, are generally adapted for life on or under the earth in the warmer, drier environments of the desert and canyon lands. These distinct survival strategies—climbing and canopy-dwelling versus burrowing and terrestrial—allow multiple species to coexist without directly competing for the same resources.
Identifying the Tree-Dwelling Species
The high-elevation forests of central and northern Arizona are the exclusive domain of the state’s arboreal squirrels, most notably the iconic Abert’s Squirrel (Sciurus aberti). This species is recognizable by its prominent, long ear tufts, which it may shed during the warmer summer months. Abert’s Squirrels are highly specialized, relying almost entirely on the Ponderosa Pine for survival.
Their diet centers on the pine tree, with consumption varying seasonally; they strip the inner bark, or phloem, from twigs in the winter and feed on the seeds from cones in the warmer months. Unlike many other squirrels, Abert’s Squirrels generally do not cache food for long periods, instead building large, spherical nests high in the Ponderosa canopy. A geographically isolated subspecies, the Kaibab Squirrel, is found only on the North Rim of the Grand Canyon and is distinguished by its entirely white tail and black body.
The Arizona Gray Squirrel (Sciurus arizonensis) is another native tree squirrel, preferring the deciduous woodlands and riparian canyons in the southern and eastern parts of the state. This animal is smaller and lacks the ear tufts of the Abert’s Squirrel. It typically lives in forests featuring sycamores, walnuts, and oaks, depending on the nuts and seeds from these broadleaf trees for sustenance.
Ground Squirrels of the Deserts and Cities
The dry, rocky, and urbanized areas of Arizona are dominated by species that thrive on the ground, utilizing burrows for shelter and temperature regulation. The Rock Squirrel (Otospermophilus variegatus) is one of the largest ground squirrels, with a long, bushy tail that makes it visually similar to a tree squirrel. This animal creates complex burrow systems in rocky outcrops, canyons, and under human-made structures.
Rock Squirrels are omnivorous and excellent climbers, often ascending trees to forage for nuts, seeds, and fruits before caching them underground. In the hottest parts of the year, they may enter a state of dormancy called estivation to avoid extreme heat.
This contrasts with the Harris’s Antelope Squirrel (Ammospermophilus harrisii), a smaller species common in the desert. The Harris’s Antelope Squirrel is active throughout the day, even during the hottest hours, and is easily identified by a single white stripe running along each side of its body.
To manage the extreme desert heat, this species employs a technique called “heat dumping,” where it lies spread-eagled on cool soil or in the shade to rapidly transfer heat away from its body. It also frequently holds its tail arched over its back, using it as a portable sunshade while foraging for seeds, insects, and cactus fruit.