Colorado’s diverse landscapes, from plains to mountain peaks, are home to various squirrel species. These adaptable rodents thrive in both wild and urban areas, with distinct types suited to specific habitats.
Tree Squirrels of Colorado
Tree squirrels in Colorado are recognized by their bushy tails and agile climbing abilities. Among the most distinctive is the Abert’s squirrel (Sciurus aberti), also known as the tassel-eared squirrel. They are typically gray to salt-and-pepper, sometimes black, with a reddish patch on their back, a white belly, and prominent ear tufts (less noticeable in summer). Abert’s squirrels are highly specialized, living almost exclusively in Ponderosa pine forests, generally found at elevations between 5,500 and 8,500 feet. Their diet primarily consists of Ponderosa pine parts, including seeds, buds, and inner bark. They do not typically store food.
The fox squirrel (Sciurus niger) is another common tree squirrel in Colorado and is the largest tree squirrel species in North America. Their fur ranges from rusty red to gray with a rusty underside. They are adaptable and frequently seen in urban and suburban areas, streamside woodlands, lower elevation forests, and agricultural areas. Their omnivorous diet includes fruits, nuts, buds, seeds, insects, and even bird eggs. They are known to bury or cache food for later consumption.
The American red squirrel (Tamiasciurus hudsonicus), often called the pine squirrel, is smaller than both the Abert’s and fox squirrels. This species has rusty red fur with a white belly and a thick white ring around its black eyes. Pine squirrels inhabit high timber forests and coniferous woodlands throughout western Colorado, including lodgepole pine forests. They primarily feed on seeds and cones of evergreen trees like spruce, fir, and lodgepole pine, and store large quantities of cones. Red squirrels remain active throughout the year and are territorial.
Ground Squirrels of Colorado
Ground squirrels prefer living on or under the ground, typically in burrows, and often have shorter tails and stouter bodies. One such species is the Wyoming ground squirrel (Urocitellus elegans), averaging 10-15 inches long and weighing 9-14 ounces. Their fur is generally brownish smoke-gray with a dappled cinnamon-buff pattern and a buff tail underside. These ground squirrels are found in northcentral and northwestern Colorado, from elevations of 5,000 feet to above the timberline, preferring open sagebrush, grasslands, and subalpine meadows. They feed on green foliage, seeds, insects, and eggs from ground-nesting birds. They hibernate underground from late July or early August until March or April.
Another significant ground squirrel species is the rock squirrel (Otospermophilus variegatus), a large, heavy-bodied rodent, 17-21 inches long. They have mottled brown and gray fur with white spots, light-colored rings around their eyes, and a long, bushy tail. Rock squirrels inhabit arid canyons, rocky cliff areas, and boulder piles, and can also be found in urban and suburban environments, avoiding high mountainous or heavily forested regions. Their diet includes seeds, nuts, berries, green vegetation, insects, and carrion. These social animals live in colonies, digging extensive burrow systems for shelter and food storage.
The golden-mantled ground squirrel (Callospermophilus lateralis) is often mistaken for a chipmunk due to its striped appearance, but it is larger and lacks facial stripes. It has a russet to golden “mantle” on its neck and shoulders, with a grayish-brown body featuring two white stripes bordered by black stripes along its sides. Golden-mantled ground squirrels are found across a wide range of elevations in Colorado, from lower areas to well above the treeline, often near rocks and woodland edges. They are omnivores, consuming fungi, leaves, fruits, seeds, insects, and occasionally small vertebrates. These squirrels are true hibernators, significantly increasing body weight in summer to prepare for winter.
Colorado’s Chipmunks
Chipmunks, members of the squirrel family, are distinguished by their smaller size, prominent striped patterns (including facial stripes), and cheek pouches for carrying food. The least chipmunk (Neotamias minimus) is the smallest chipmunk species in North America, typically 6.2-9.8 inches long. Its body is gray to reddish-brown with grayish-white underparts, and it has five dark stripes on its back separated by four lighter stripes, along with facial stripes. This widespread species inhabits diverse environments, from low sagebrush deserts to high mountain coniferous forests and open areas. Least chipmunks are diurnal, foraging for seeds, berries, nuts, and insects. They enter torpor during winter, waking periodically to feed on stored provisions.
The Uinta chipmunk (Neotamias umbrinus) is a medium-sized chipmunk, generally 8-9.5 inches long. Its coloration ranges from yellowish brown-gray to dark brown, with wide brown stripes on its back alternating with white stripes. Uinta chipmunks are often found in Colorado’s central mountains, preferring the margins of pine and fir forests, clearings, rocky areas, or steep slopes. They are active during the day, territorial, and collect food to store for winter, undergoing periods of torpor.
The Colorado chipmunk (Neotamias quadrivittatus) is a medium to large chipmunk, measuring approximately 200-245 millimeters long. It features a black central dorsal stripe, reddish-brown lateral stripes, and well-defined white lateral stripes. This species is found in southern Colorado and northward along the Eastern Slope foothills, often in rocky, broken terrain within open woodlands, shrublands, and montane forests. Colorado chipmunks are primarily terrestrial but also skilled climbers. They are typically solitary, foraging in the early morning and late afternoon, and hibernate during winter.