Ground squirrels are prolific diggers, a defining characteristic of these common rodents. They create extensive, complex burrow systems beneath the surface. Digging is a fundamental and ingrained behavior, serving as a primary means for their survival.
Purposes for Digging
Ground squirrels dig for multiple reasons, all linked to their survival and well-being. Their burrows provide essential shelter from unpredictable weather patterns, offering refuge from intense heat, cold temperatures, and heavy rain. These underground homes maintain a stable microclimate, shielding the squirrels from environmental extremes.
Burrows also serve as a defense mechanism against predators. When faced with threats such as hawks, coyotes, or snakes, ground squirrels quickly retreat into their intricate tunnel systems, finding immediate safety. The multiple entrances and complex layouts of these burrows make it challenging for predators to pursue them.
Another purpose for digging is food storage. Many ground squirrel species cache seeds, nuts, and other food items in specialized chambers within their burrows. This stored food provides a vital supply during periods of scarcity, particularly through winter months or when surface foraging is limited.
Burrows are also nurseries for raising young. Female ground squirrels construct nests within these underground spaces, providing a protected environment for their vulnerable pups. These nests, often lined with soft materials like grass, keep the young safe from predators and harsh elements during their early development.
Many ground squirrel species use their burrows for periods of dormancy. This includes hibernation during colder winter months and estivation in response to summer heat or drought conditions. During these periods, they enter a state of reduced metabolic activity, relying on the stable burrow environment to conserve energy.
Anatomy of a Ground Squirrel Burrow
Ground squirrel burrows are complex underground networks. Entrance holes are typically circular, measuring about 4 to 5 inches in diameter. These entrances are often clean, without significant mounds of excavated soil directly around them, as squirrels tend to scatter the dirt.
The burrow system extends into a network of tunnels. Tunnel lengths commonly range from 5 to 30 feet, though some complex systems can reach up to 138 feet horizontally. While most tunnels are within 2 to 3 feet of the surface, portions can extend to depths of 6 feet or more.
Within these tunnel systems are various chambers. Sleeping or nesting chambers are often lined with dried grass or other soft materials, providing comfortable spaces for rest and rearing young. Other chambers are for food storage. Additionally, burrows often include escape tunnels or “bolt holes,” which are secondary, often inconspicuous, exits allowing for quick evasion from threats.
Preferred Digging Locations
Ground squirrels prefer certain environmental conditions for their burrows. They favor well-drained, loose soil that is easy to excavate yet stable enough to prevent collapse. Sandy loam is an example of a soil type that meets these criteria.
Vegetation cover also influences burrow placement. Ground squirrels often dig near bushes or tall grasses, which provide concealment from predators. They also frequent open areas for foraging and sunning.
Topography plays a role in their selection. Ground squirrels often prefer slight slopes, embankments, or elevated areas. These locations offer good natural drainage, minimizing the risk of water accumulation within the burrow system, and provide improved visibility for spotting potential threats.
Ground squirrels can establish burrows in areas influenced by human activity. They are commonly found digging in agricultural fields, pastures, and orchards, where food sources may be abundant. They can also inhabit suburban areas, including parks, golf courses, and residential lawns.