Arizona has a significant and diverse population of squirrels that thrive across the state’s varied landscape. These rodents inhabit environments ranging from the high-elevation coniferous forests of the north to the low-lying Sonoran Desert in the south. The presence of squirrels is not limited to a single type, demonstrating remarkable adaptability to different climates and ecosystems. Their existence highlights the biological success of various species in finding food and shelter where resources can be scarce.
The Abundance of Squirrels in Arizona
The squirrel population in Arizona is broadly categorized into two major groups: tree squirrels and ground squirrels. Tree squirrels, belonging to the genus Sciurus, are built for life in trees, featuring long, bushy tails for balance and strong limbs for climbing. They typically construct their nests, called dreys, high in tree branches.
Ground squirrels, which include genera like Otospermophilus and Ammospermophilus, are adapted for life on or under the earth. These species dig complex burrow systems that provide shelter from predators and the desert heat. Some ground squirrels, such as the Rock Squirrel, can also climb trees and shrubs when foraging for food.
Defining Arizona’s Unique Species and Range
Arizona is home to at least a dozen species of squirrels, each occupying a specific ecological niche based on elevation and vegetation. One of the most recognizable is the Abert’s Squirrel (Sciurus aberti), often called the tassel-eared squirrel for the prominent tufts of fur on its ears. This species is almost exclusively confined to the Ponderosa pine forests across the Mogollon Rim and other high-elevation areas, primarily feeding on pine cone seeds and inner bark.
The Rock Squirrel (Otospermophilus variegatus) is a large ground squirrel found across a wide range of habitats, from canyons and rocky cliffs to suburban areas. It is a versatile species, often seen perched on boulders or foraging near human structures, and may hibernate during the winter months in the northern parts of its range. The Harris’s Antelope Squirrel (Ammospermophilus harrisii) is a true desert specialist, thriving in the low-lying Sonoran Desert regions of central and southern Arizona.
The Harris’s Antelope Squirrel is a small, striped ground squirrel that is active year-round. Another native species is the Arizona Gray Squirrel (Sciurus arizonensis), which prefers the deciduous woodlands and riparian corridors of the southeastern part of the state. Its survival is sometimes challenged by competition from the dominant Abert’s Squirrel in certain areas.
Behavioral and Physical Adaptations for Desert Survival
Squirrels in Arizona’s arid regions have developed specialized behaviors to cope with intense heat and limited water. Many desert species, such as the Harris’s Antelope Squirrel, are active during the day, even in high temperatures, and manage heat through “heat dumping.” When their body temperature reaches its upper limit, they retreat to a cool, shaded spot and flatten their bodies against the cooler ground to transfer heat away.
Burrowing is another widespread strategy, providing a stable microclimate that is significantly cooler than the surface during the summer. Ground squirrels, including the Rock Squirrel, utilize these underground shelters as a thermal refuge and for safety. The Harris’s Antelope Squirrel also carries its bushy tail arched over its back, which provides personal shade while foraging.
These squirrels also have sophisticated methods for conserving water. They primarily obtain the moisture they need from their diet, consuming succulent vegetation, bulbs, and seeds rather than relying on open water sources. The ability of Rock Squirrels to withstand long periods without free water is a testament to their physiological efficiency in a dry climate. Some desert species also enter periods of estivation, a state of summer dormancy, to avoid the hottest and driest parts of the year.
Managing Residential Interactions
Squirrels are highly adaptable and frequently move into urban and suburban environments in Arizona, leading to common conflicts with residents. These interactions often involve property damage, as squirrels may dig holes in lawns and gardens while burying or foraging for food. Tree squirrels view attics and eaves as ideal substitutes for natural tree hollows, where they build nests and seek shelter.
Once inside a structure, they can cause significant problems by chewing on electrical wiring, which presents a fire hazard, and by damaging insulation with nesting materials and droppings. The most effective approach to managing these residential issues involves exclusion and habitat modification. Trimming tree branches that overhang a roof can eliminate a common access point, as squirrels can easily jump onto a structure.
Securing potential food sources is also important, including using squirrel-proof bird feeders and ensuring trash cans are tightly sealed. For entry into homes, sealing all gaps and holes with durable, chew-resistant materials like steel mesh is necessary to prevent re-entry. When a squirrel has established a nest inside, humane live trapping and relocation, often performed by professionals, is necessary before permanent exclusion can be completed.