You might expect to see the classic bushy-tailed tree squirrels scampering through Phoenix neighborhoods, but the desert has other plans. The Sonoran Desert is home to ground-dwelling species perfectly adapted to Arizona’s arid climate, and they’re thriving right in your backyard.
Whether you’re spotting them darting across hiking trails or raiding your bird feeder, understanding which squirrels live in Phoenix helps you appreciate these resourceful desert survivors.
Rock Squirrel
The Rock squirrel (Otospermophilus variegatus) is the largest and most commonly encountered squirrel species in the Phoenix area. These robust rodents have adapted remarkably well to urban environments, making them frequent visitors to residential yards, parks, and hiking trails throughout the Valley.
Physical Characteristics and Identification
You’ll recognize rock squirrels by their mottled gray-brown fur with a distinctive grizzled appearance on their backs. They measure 17-21 inches from nose to tail tip, with their bushy tails accounting for nearly half that length. Unlike their smaller cousins, rock squirrels have a stocky build that makes them appear almost cat-sized when fully grown, weighing between 1-2 pounds.
Pro Tip: Rock squirrels often hold their tails curved over their backs when alert, creating an iconic silhouette that distinguishes them from other desert squirrels.
Their coloring provides excellent camouflage among Phoenix’s rocky desert landscapes. The fur transitions from lighter gray on their undersides to darker, salt-and-pepper tones across their backs and heads. Some individuals display more brownish tones, particularly during summer months when their coats may appear sun-bleached.
Habitat and Behavior Patterns
Rock squirrels thrive in rocky outcroppings, boulder fields, and canyon areas throughout Phoenix. They’ve also adapted brilliantly to urban settings, establishing colonies in parks and residential areas where rock walls, decorative boulders, and concrete structures provide suitable den sites.
These squirrels are primarily diurnal, meaning you’ll spot them most actively during early morning and late afternoon hours. During Phoenix’s brutal summer months, they adjust their schedules to avoid peak heat, emerging earlier at dawn and later in the evening. They’re also known to estivate—a summer dormancy similar to hibernation—during the hottest weeks of July and August.
Common Mistake: Many Phoenix residents mistake rock squirrels for prairie dogs due to their ground-dwelling habits and similar size, but rock squirrels have much longer, bushier tails and more agile climbing abilities.
Rock squirrels are omnivorous opportunists with diverse diets. They consume:
- Seeds, nuts, and fruits from desert plants like palo verde and mesquite
- Prickly pear cactus pads and fruits
- Insects, bird eggs, and occasionally small vertebrates
- Human food sources including pet food, garden vegetables, and bird seed
Their adaptability to human food sources has made them both beloved and problematic in Phoenix neighborhoods. While entertaining to watch, they can cause property damage by burrowing under foundations and chewing through irrigation systems.
Social Structure and Communication
Rock squirrels live in loose colonies with complex social hierarchies. You’ll often observe them engaging in elaborate greeting rituals, including nose-touching and mutual grooming. They communicate through a variety of vocalizations:
- Sharp, high-pitched alarm calls when predators approach
- Chattering sounds during territorial disputes
- Soft chirping between mothers and juveniles
Their burrow systems can be extensive, with multiple entrances and chambers for nesting, food storage, and escape routes. These underground networks may extend 3-6 feet deep and span 20-30 feet horizontally.
Harris’s Antelope Squirrel
The Harris’s antelope squirrel (Ammospermophilus harrisii) represents one of the most heat-adapted mammals in the Sonoran Desert. These small, energetic squirrels remain active even during Phoenix’s scorching summer afternoons when most wildlife seeks shelter.
Distinctive Features and Size
You’ll immediately notice the Harris’s antelope squirrel by the single white stripe running along each side of its body from shoulder to hip. This bold marking contrasts sharply against their grayish-brown fur, making identification straightforward even from a distance. They’re considerably smaller than rock squirrels, measuring just 8-10 inches total length and weighing only 4-5 ounces—about the size of a chipmunk.
Key Insight: The white stripe on Harris’s antelope squirrels serves as a visual cue that helps individuals recognize each other across the desert’s open spaces, functioning like a natural identification badge.
Their tails are distinctive—relatively short compared to rock squirrels, with a white underside that flashes prominently when held upright. Unlike tree squirrels, their tails aren’t particularly bushy, appearing more like thin, flexible flags that they wave during territorial displays and alarm signals.
Heat Tolerance Adaptations
Harris’s antelope squirrels have evolved remarkable physiological adaptations for extreme heat. They can tolerate body temperatures exceeding 107°F—levels that would be fatal to most mammals. When their body temperature rises too high, they retreat briefly to their burrows to cool down, then resume foraging.
You’ll observe several behavioral cooling strategies:
- Saliva spreading: They lick their fur to promote evaporative cooling
- Heat dumping: They press their bodies against cool burrow walls
- Tail shading: They position their tails over their backs as portable sunshades
- Strategic timing: They make quick foraging trips, alternating between surface activity and burrow cooling
These adaptations allow Harris’s antelope squirrels to remain active during midday hours when other desert animals are inactive, giving them exclusive access to food resources during Phoenix’s hottest months.
Diet and Foraging Behavior
Harris’s antelope squirrels are omnivorous with preferences shifting seasonally. Their diet includes:
- Seeds from grasses, shrubs, and desert annuals
- Insects, particularly during spring and summer when protein needs increase
- Cactus fruits and pads, especially saguaro and prickly pear
- Green vegetation during brief periods following monsoon rains
Unlike rock squirrels, Harris’s antelope squirrels don’t typically cache large food stores. Instead, they employ a “live fast” strategy, foraging daily and maintaining high metabolic rates. You’ll see them scurrying rapidly across open ground, moving in characteristic stop-and-go patterns while scanning for predators.
Territorial and Reproductive Patterns
These squirrels are notably territorial, with each individual defending a home range of 2-4 acres. Males and females maintain separate territories except during breeding season, which typically occurs from February through June in the Phoenix area. Aggressive encounters between neighbors are common, involving tail-flagging displays, chasing, and occasional physical combat.
Females raise 5-14 young per litter in underground nests lined with grass and other soft materials. The young emerge above ground after about 6-8 weeks and disperse to establish their own territories by late summer.
Round-Tailed Ground Squirrel
The Round-tailed ground squirrel (Xerospermophilus tereticaudus) is the least conspicuous squirrel species in Phoenix, often going unnoticed despite being relatively common in appropriate habitats. Their cryptic coloring and shy behavior make them the “ghost squirrels” of the Sonoran Desert.
Identification Challenges and Key Features
Round-tailed ground squirrels present identification challenges because they lack distinctive markings. Their uniform cinnamon-gray to pinkish-buff coloring blends seamlessly with desert soil, and their most distinctive feature—the round, pencil-thin tail that gives them their name—isn’t always visible when they’re at rest.
| Feature | Round-Tailed Ground Squirrel | Rock Squirrel | Harris’s Antelope Squirrel |
|---|---|---|---|
| Size | 8-11 inches total length | 17-21 inches total length | 8-10 inches total length |
| Weight | 4-6 ounces | 1-2 pounds | 4-5 ounces |
| Tail Type | Thin, round, minimal hair | Bushy, full | Moderately haired, white below |
| Stripes | None | None | Single white stripe each side |
| Coloring | Uniform beige/cinnamon | Mottled gray-brown | Grayish-brown with white stripe |
Important Note: Round-tailed ground squirrels are frequently confused with young rock squirrels, but the consistently thin tail and uniform coloring distinguish them at all life stages.
They measure 8-11 inches total length with approximately half devoted to their distinctive tail. Adults weigh 4-6 ounces, making them similar in size to Harris’s antelope squirrels but stockier in build. Their small, rounded ears sit close to their heads, and their eyes are proportionally large—adaptations for detecting predators in open desert environments.
Habitat Preferences in Phoenix
Round-tailed ground squirrels show strong preferences for sandy or loose soils where digging burrows requires less energy. In the Phoenix area, you’ll find them in:
- Desert washes and sandy arroyos
- Agricultural field margins, particularly around alfalfa and cotton fields
- Desert golf courses with sandy soil
- Undeveloped lots in newer subdivisions built on desert land
- Desert preserves and natural areas with appropriate substrate
Unlike rock squirrels that adapt readily to urban hardscapes, round-tailed ground squirrels struggle in heavily developed areas where native soil has been removed or compacted. They’re more common on Phoenix’s urban fringe where desert habitat remains relatively intact.
Daily Activity Patterns and Behavior
Round-tailed ground squirrels exhibit bimodal activity patterns that shift seasonally with temperature. During spring and fall, they’re active mid-morning through mid-afternoon. Summer heat pushes their activity to early morning hours (6-9 AM) and late afternoon (5-7 PM), with extended periods underground during peak heat.
Their behavior differs markedly from the more conspicuous rock squirrels:
- They forage close to burrow entrances, rarely venturing more than 30-50 feet away
- They freeze motionless when alarmed rather than fleeing obviously
- They’re less vocal than rock squirrels, giving only soft chirping sounds
- They avoid human contact, disappearing quickly when approached
Pro Tip: Watch for round-tailed ground squirrels near the base of creosote bushes and mesquite trees, where they often position burrow entrances to take advantage of root systems that stabilize sandy soil.
Dietary Habits and Seasonal Variations
Round-tailed ground squirrels are primarily herbivorous, with diets shifting dramatically between seasons. Spring and early summer diets emphasize green vegetation when desert annuals flourish after winter rains. As vegetation dries, they transition to seeds, particularly from grasses and desert plants like bursage and brittlebush.
During late summer monsoon season, they consume:
- Fresh green shoots from revitalized desert plants
- Seeds from summer annuals
- Occasional insects for protein supplementation
- Mesquite pods when available
They don’t hibernate but enter torpor—a short-term reduced metabolic state—during extremely hot periods or when food becomes scarce. This adaptation allows them to survive Phoenix’s environmental extremes without maintaining year-round food caches like some squirrel species.
Arizona Gray Squirrel
The Arizona gray squirrel (Sciurus arizonensis) represents a different ecological strategy among Phoenix-area squirrels. Unlike the ground-dwelling species common in the city proper, Arizona gray squirrels are true tree squirrels that require substantial woodland habitat—a resource largely absent from Phoenix’s urban core.
Distribution Around Phoenix
You won’t typically encounter Arizona gray squirrels within Phoenix city limits. Their range centers on mountain and riparian areas north and east of the metro area, particularly in:
- Tonto National Forest corridors along Highway 87 toward Payson
- Riparian zones along the Verde River northeast of Phoenix
- Forested areas in the Mazatzal Mountains
- Canyon habitats in the Superstition Mountains’ higher elevations
- Oak-sycamore woodlands above 3,500 feet elevation
Key Insight: If you spot what appears to be a gray tree squirrel within Phoenix proper, it’s more likely an introduced non-native species like the fox squirrel or eastern gray squirrel rather than the native Arizona gray squirrel.
These squirrels require mature trees with interconnected canopies for travel and foraging. Phoenix’s urban forest, dominated by non-native palms and small ornamental trees, doesn’t provide suitable habitat. However, residents who venture into nearby mountain communities like Pine, Payson, or Cave Creek’s northern reaches regularly observe Arizona gray squirrels.
Physical Characteristics and Appearance
Arizona gray squirrels display the classic tree squirrel body plan: large bushy tail, strong hind legs for leaping, and sharp claws for bark climbing. They measure 18-22 inches total length with their distinctive plume-like tail contributing significantly to that measurement. Adults weigh 1-1.5 pounds—noticeably larger than the ground squirrels common in Phoenix but smaller than rock squirrels.
Their coloring varies seasonally and individually:
- Summer coat: Shorter, sleeker fur in steel gray tones with rusty-brown highlights along the back
- Winter coat: Longer, denser fur in darker gray with more pronounced brown or reddish tones
- Underside: White to cream-colored belly and throat
The tail shows distinctive banding with alternating dark and light rings most visible when backlit. Their ears are proportionally larger than ground squirrels’, tufted with fine hairs that become more prominent in winter.
Habitat Requirements and Tree Dependencies
Arizona gray squirrels are intimately tied to oak-pine-juniper woodlands and riparian forests. They show strong preferences for:
- Oak trees: Particularly Emory oak, Arizona white oak, and silverleaf oak for acorn crops
- Walnut trees: Arizona walnut in canyon bottoms provides crucial food and nesting sites
- Sycamores: Large sycamores in riparian corridors offer nesting cavities and travel routes
- Pines: Ponderosa and piñon pines supplement diet with seeds
Unlike ground squirrels that excavate burrows, Arizona gray squirrels construct leaf nests (dreys) in tree branches or occupy natural tree cavities. A single individual may maintain 2-3 nests within its home range, rotating between them seasonally or when disturbed by predators.
Behavior and Diet Patterns
Arizona gray squirrels exhibit typical tree squirrel behaviors: they’re diurnal, most active during morning and late afternoon hours, and remain active year-round without hibernating or estivating. Their diet centers on tree-produced foods:
- Acorns form the dietary staple from fall through winter
- Tree seeds including pine nuts supplement acorn shortages
- Buds and flowers provide spring nutrition
- Fungi and lichens diversify the diet year-round
- Bark and twigs serve as emergency food during scarcity
They exhibit food caching behavior, burying individual nuts and seeds throughout their territory—a behavior called scatter-hoarding. This foraging strategy inadvertently plants countless oak and walnut trees, making Arizona gray squirrels important ecosystem engineers in mountain forests.
Conservation Status and Viewing Opportunities
Arizona gray squirrels are endemic to Arizona and a small portion of New Mexico, meaning they exist nowhere else on Earth. While not currently listed as threatened, their dependence on mature forest habitat makes them vulnerable to wildfire, logging, and climate change.
For Phoenix residents interested in observing Arizona gray squirrels, several accessible locations offer opportunities:
- Tonto Natural Bridge State Park: Riparian forest habitat near Payson
- Boyce Thompson Arboretum: Upper elevation areas with mature trees
- Highway 87 corridor: Various pullouts and forest access roads north of Sunflower
- Apache-Sitgreaves National Forest: Christopher Creek and Woods Canyon Lake areas
Bring binoculars and watch for movement in tree canopies during early morning hours for the best viewing success.
Abert’s Squirrel
Abert’s squirrel (Sciurus aberti), also called the tassel-eared squirrel, stands out as the most distinctive squirrel species in Arizona. While uncommon around Phoenix, understanding this charismatic species enriches your knowledge of Arizona’s diverse squirrel community.
Geographic Range Relative to Phoenix
Abert’s squirrels inhabit ponderosa pine forests at elevations generally above 6,000 feet—well above Phoenix’s 1,000-foot elevation. You’ll need to travel significantly north or east from Phoenix to encounter them:
- Mogollon Rim: The primary habitat zone begins roughly 90 miles north of Phoenix
- Flagstaff area: Consistent populations throughout surrounding ponderosa pine forests
- White Mountains: Eastern Arizona populations in Apache-Sitgreaves National Forest
- Mount Graham: Isolated populations in southeastern Arizona’s higher elevations
Important Note: Claims of Abert’s squirrel sightings within Phoenix proper are typically misidentifications of rock squirrels or, occasionally, introduced fox squirrels with unusually colored fur.
The nearest reliable viewing locations from Phoenix include:
- Forest Lakes area along Highway 260 (approximately 130 miles)
- Woods Canyon Lake recreation area (approximately 140 miles)
- Flagstaff urban forest and surrounding Coconino National Forest (approximately 145 miles)
Unmistakable Physical Features
Abert’s squirrels are impossible to confuse with other species once you know their distinctive features. Their most striking characteristic is the prominent ear tufts—long black hairs extending 1-2 inches above each ear that give them a lynx-like appearance. These tufts are most pronounced during winter months and may reduce or disappear entirely during summer molts.
| Season | Coat Coloring | Ear Tufts | Tail Characteristics |
|---|---|---|---|
| Winter | Dark gray to black back, white belly | Prominent (1-2 inches) | Extremely bushy, silver-white with black stripe |
| Summer | Lighter gray, less contrast | Reduced or absent | Somewhat less dense but still impressive |
Adult Abert’s squirrels measure 18-23 inches total length and weigh 1.25-1.75 pounds, making them similar in size to Arizona gray squirrels. However, their spectacular tail—broad, extremely bushy, and often white or silver with a distinctive black dorsal stripe—creates a much larger visual impression.
Ponderosa Pine Dependency
Abert’s squirrels represent one of nature’s most specialized relationships between mammal and tree. They depend almost exclusively on ponderosa pine forests for survival, rarely occurring where ponderosas are absent. This specialization influences every aspect of their biology:
Dietary specialization includes:
- Ponderosa pine inner bark (cambium layer) forms up to 75% of winter diet
- Pine cones and seeds provide autumn nutrition
- Terminal buds sustain them during early spring
- Hypogeous fungi (underground mushrooms) supplement summer diet
This extreme specialization makes Abert’s squirrels vulnerable to ponderosa pine decline. Climate change and catastrophic wildfires increasingly threaten their habitat, with some forecasts suggesting significant range contractions by mid-century.
Unique Behaviors and Ecology
Abert’s squirrels exhibit fascinating behaviors adapted to their pine forest environment. They construct large platform nests (dreys) in ponderosa pine branches, typically 20-40 feet above ground. Each squirrel maintains multiple nests within its home range, using different structures for different purposes—some for sleeping, others for raising young or escaping predators.
Pro Tip: Look for Abert’s squirrel nests during winter when deciduous understory vegetation has dropped leaves—they appear as basketball-sized masses of pine needles and twigs wedged in tree forks.
Their communication system is complex and vocal. You’ll hear:
- Loud, dog-like barking when alarmed or during territorial disputes
- Softer chattering sounds during social interactions
- Drumming sounds created by rapidly beating their tails against tree bark
Abert’s squirrels don’t hibernate but their activity levels decrease dramatically during winter’s coldest periods. They remain in their nests for extended periods, emerging mainly during warm afternoon hours to feed on stored cone caches or bark.
Population Dynamics and Color Variations
Abert’s squirrel populations fluctuate with ponderosa pine cone production, which varies dramatically year-to-year. Mast years (heavy cone production) support larger populations, while crop failures lead to dispersal, starvation, and population crashes.
A fascinating aspect of Abert’s squirrel biology is their color variation. While the typical form has a dark gray back and white belly, several color morphs exist:
- All-black melanistic form: Rare individuals entirely black except for white ear tufts
- Brown morph: Rusty-brown replacing gray tones
- Kaibab squirrel: An isolated subspecies north of Grand Canyon with all-white tail and dark belly
These color variations provide natural laboratories for studying evolution and genetic isolation in squirrel populations across Arizona’s sky islands—forested mountain ranges separated by lower-elevation deserts.
Phoenix’s squirrel community reflects the Sonoran Desert’s unique ecological character. While you won’t find the bushy-tailed tree squirrels common in wetter climates climbing through city parks, the ground-dwelling species here demonstrate remarkable adaptations to desert life.
Rock squirrels and Harris’s antelope squirrels thrive in urban settings, entertaining residents while occasionally testing homeowner patience.
Round-tailed ground squirrels quietly occupy desert fringes, and the tree-dwelling Arizona gray and Abert’s squirrels wait in nearby mountains for visitors willing to explore higher elevations. Understanding these five species enriches your appreciation for the wildlife thriving in and around the Valley of the Sun.
