Some snakes can dig their own burrows, while many others rely on existing underground structures for shelter. The ability to create a burrow is not universal, requiring specific physical adaptations. While some snakes are “fossorial,” adapted for life underground, most are opportunistic, utilizing existing holes and crevices. This highlights the diverse ways snakes use subterranean spaces.
Snakes That Actively Dig
Certain snake species possess specialized physical traits enabling them to actively dig their own burrows. Hognose snakes, for example, use their upturned, shovel-like snouts to excavate sandy soils, creating intricate tunnels and chambers. Similarly, sand boas, with stout bodies and wedge-shaped heads, burrow rapidly beneath loose soil or sand; their eyes are positioned on top, allowing them to peer above the surface. Other digging snakes, like the Brahminy blind snake, resemble worms and tunnel through soft, moist soil. These burrowing snakes often have small heads and smooth, polished scales, which may reduce friction or repel dirt as they move through the ground.
Snakes That Use Pre-Existing Burrows
The majority of snake species do not actively dig their own burrows but instead use existing underground shelters. These snakes are opportunistic, seeking out natural cavities or abandoned tunnels created by other animals. Common choices include abandoned rodent burrows, rock crevices, hollow logs, and spaces under rocks or building foundations.
Many species, such as garter snakes and rat snakes, frequently utilize these pre-existing structures. Garter snakes, for instance, often gather in large communal dens, known as hibernacula, which can be natural cavities or even man-made structures. Black rat snakes also share winter dens, sometimes with other snake species. These snakes often choose snug holes where they can feel secure, as too much space can make them vulnerable to predators.
Reasons Snakes Seek Underground Shelter
Snakes seek underground shelter for several reasons related to their survival and well-being. A primary motivation is thermoregulation, as snakes are ectothermic and rely on external heat sources to maintain their body temperature. Burrows offer stable temperatures, providing refuge from extreme heat during hot days and insulation from freezing cold during winter months. This thermal stability is important for processes like brumation, a dormant state similar to hibernation, where snakes slow their metabolism.
Underground spaces also provide protection from predators, such as birds of prey and larger mammals, offering a safe haven where snakes can remain hidden. Some snakes use burrows as strategic hunting grounds, ambushing prey like rodents that also inhabit these underground tunnels. Underground shelters also serve as safe locations for reproduction. Many egg-laying snakes deposit their clutches in hidden, damp places like soil or abandoned burrows, which offer a stable environment for egg development. Live-bearing species may also use these spaces to give birth, providing immediate protection for their young.