Squirrels are an abundant and highly diverse group of mammals found throughout Arizona. The state’s varied landscape, which includes high-elevation forests, riparian corridors, and Sonoran desert scrub, supports a wide array of species from the Sciuridae family. Arizona is home to multiple distinct types of squirrels, each adapted to a specific ecological niche.
Identifying Arizona’s Unique Tree Squirrels
Arizona hosts several species of true arboreal squirrels, including the Abert’s Squirrel (Sciurus aberti). This species is often called the tassel-eared squirrel because of the prominent tufts of hair that grow from its ears, which generally disappear during the summer months. It exhibits a dark gray coat, a white belly, and frequently has a distinct reddish-brown patch running down its back.
The Abert’s squirrel is almost exclusively associated with mature Ponderosa pine forests across the Mogollon Rim and mountain ranges like the Sky Islands. Its specialized diet relies on the seeds, cones, fungi, and inner bark of Ponderosa pine twigs. A unique subspecies, the Kaibab squirrel (Sciurus aberti kaibabensis), is isolated to the Kaibab Plateau north of the Grand Canyon and is distinguished by its entirely white tail and dark belly.
The Arizona Gray Squirrel (Sciurus arizonensis) is a native species found in the deciduous forests of canyons and riparian habitats in the central and southeastern regions. It lacks ear tufts and is characterized by a mostly gray body, a long bushy tail edged in white, and a pale underbelly. This species prefers mid-elevations (5,000 to 6,000 feet), thriving in areas with walnut, oak, and sycamore trees. The introduction of the Abert’s squirrel in some areas, such as the Rincon Mountains, has led to resource competition and a decline in the native population.
Ground Squirrels and Chipmunks
The Sciuridae family includes many terrestrial species, such as ground squirrels and chipmunks, which differ significantly from arboreal species in behavior and appearance. Instead of building nests in tree canopies, these species live in burrows they dig in the ground. They retreat to these burrows for safety and to raise their young.
The Rock Squirrel (Spermophilus variegates) is one of the largest ground squirrels in Arizona, often mistaken for the Arizona Gray Squirrel due to its mottled gray and brown coloration and bushy tail. Its preference for rocky outcrops, canyons, and cliff faces, where it digs its burrows, serves as the primary identifier. This species is widespread, inhabiting areas from high mountains down to the desert floor.
In the lower, arid regions, the Harris’s Antelope Squirrel (Ammospermophilus harrisii) is common, recognizable by a single white stripe running along each side of its body. This desert dweller is active throughout the year and is often seen scurrying across the ground. Chipmunks, such as the Cliff Chipmunk (Tamius dorsalis), are smaller and are differentiated from antelope squirrels by having stripes on their faces in addition to the stripes along their bodies.
Habitat and Geographic Range
The Abert’s Squirrel’s range is almost entirely defined by the presence of Ponderosa pine forests, which dominate high-elevation plateaus like the Mogollon Rim and the isolated mountain ranges known as Sky Islands. This habitat provides the specific food source and nesting material necessary for the species’ survival.
The Arizona Gray Squirrel is found in the more restricted, moisture-rich deciduous and mixed forests of canyons and mountain slopes, typically south of the Mogollon Rim. This species relies on the nuts and seeds produced by riparian trees like walnuts and oaks in mid-elevation environments. The smallest tree squirrel, the Red Squirrel (Tamiasciurus hudsonicus), occupies the highest elevations, specifically the spruce and fir forests above 8,500 feet.
The Round-tailed Ground Squirrel (Spermophilus tereticaudus) prefers the flat, sandy soils of the Sonoran Desert, where it digs its burrows beneath creosote bushes. The Rock Squirrel, as its name suggests, is found where rocky terrain is abundant, using the crevices and boulders of foothills and canyons for protection and observation posts.