Ground squirrels are a diverse group of rodents belonging to the family Sciuridae, which also includes tree squirrels, flying squirrels, and marmots. Unlike their arboreal relatives, ground squirrels primarily live on or under the earth in extensive tunnel systems they excavate themselves. Because of their terrestrial habits, they are often mistakenly identified as gophers, prairie dogs, or chipmunks. These animals are found across North America and Eurasia.
General Physical Characteristics
Ground squirrels generally possess a more compact and stocky build than the sleek, slender forms of tree squirrels, a body shape well-suited for digging and navigating tight underground tunnels. Their overall length typically ranges between 6 and 12 inches, though this measurement varies widely across the more than 60 species in the group. Most species weigh approximately one pound or less, with weight fluctuating significantly as they gain mass to prepare for hibernation. They are supported by short, sturdy legs, which provide the necessary power for their burrowing lifestyle.
The fur of ground squirrels is often dense and short, providing insulation and protection within their subterranean homes. Coloration tends toward natural camouflage to blend with their surroundings on the ground. The most common colors are various shades of gray, reddish-brown, or sandy brown, frequently exhibiting a mottled or flecked pattern across their backs. Their undersides are usually a lighter shade than their dorsal coats, which helps them blend in when viewed from below by predators.
Distinctive Anatomical Features
Ground squirrels are distinguished by their tail structure, which is noticeably different from that of their tree-dwelling cousins. They typically have a shorter, flatter tail that is less bushy and flowing than the large, plume-like tail used by tree squirrels for balance and communication. This less prominent tail is often held flat against the ground or only slightly arched when they are on the move.
The presence of internal cheek pouches is a key anatomical feature related to their foraging strategy. These specialized pockets inside the mouth allow the ground squirrel to quickly gather and transport large quantities of seeds, nuts, and vegetation back to their burrows. Their sensory organs are also adapted for a life spent near the ground, typically featuring smaller, less prominent ears and rounded heads. The forefeet are equipped with strong, sharp claws that are essential tools for excavating and maintaining their complex burrow systems.
Common North American Species and Markings
The Thirteen-lined Ground Squirrel (Spermophilus tridecemlineatus) is immediately recognizable by its slender body and striking pattern. Its back is marked with 13 alternating dark and light longitudinal stripes running from the neck to the tail. Within the dark stripes, there are rows of lighter spots, creating a distinctive, segmented look.
The California Ground Squirrel (Otospermophilus beecheyi) presents a more traditional mottled appearance, with fur that is a mix of brownish-gray and tawny colors. This species is larger and often displays a characteristic cape of darker, flecked fur around the neck and shoulders. The Richardson’s Ground Squirrel (Urocitellus richardsonii) is distinguished by its plain, tan or light brown fur with a mottled pattern, often described as resembling a thinner prairie dog.
Behavioral and Habitat Indicators
Observing where and how a squirrel is acting provides strong evidence of its identity as a ground squirrel. Their preferred habitats are open areas with low vegetation, such as grasslands, meadows, parks, golf courses, and suburban lawns, which allow for easy burrowing. They require well-drained soil for the construction of their elaborate, multi-chambered underground dens.
A common posture is the “picket-pin” stance, where the animal sits bolt upright on its hind legs to survey the surrounding area for danger. When startled, a ground squirrel will not instinctively climb a nearby tree, but instead will dart low to the ground and disappear into the nearest burrow entrance.