Voles are small rodents that have adapted to a life largely spent near or beneath the soil surface. These herbivores primarily consume grasses, seeds, and root systems, which motivates their prolific digging behavior. The complex network of tunnels they create serves as their home, highway for foraging, and protection from predators.
Surface Signatures of Vole Activity
The easiest way to identify a vole problem is by observing the distinct signs they leave above ground. Voles create narrow, visible pathways, known as runways, through the grass or mulch as they travel between burrow entrances and feeding sites. These runways are about one to two inches wide and often have the grass clipped down to the soil, giving the appearance of a shallow trench.
Vole entry holes are clean, small, and circular, typically measuring between one and one and a half inches in diameter. Unlike other burrowing animals, voles do not usually leave a volcano-shaped mound of excavated soil next to their holes. This lack of a dirt pile helps distinguish their entrances from the larger mounds created by gophers or moles. The presence of fresh grass clippings or rice-sized droppings near the runways confirms that the system is currently active.
Subsurface Dimensions and Depth
The depth to which voles dig their tunnels is highly variable and depends on the tunnel’s purpose. The majority of their tunneling activity occurs very close to the surface, often only one to three inches deep. These shallow tunnels are primarily for foraging, allowing the voles to feed directly on the roots and bulbs of plants. This near-surface activity can make the soil feel spongy when walked upon, which is a common indicator of an extensive tunnel system just below the sod.
For more permanent structures, such as main galleries and nesting chambers, voles dig considerably deeper. These deeper tunnels typically extend six to twelve inches below the surface. In loose soil or where protection from cold winter temperatures is necessary, voles may tunnel even deeper, occasionally reaching up to eighteen inches or more. The tunnel diameter is narrow, matching the size of the rodent, measuring about one and a half to two inches across. Soil type also influences depth, allowing deeper digging in sandy earth than in heavy clay.
Tunnel Function and Structure
A vole’s burrow is a complex, multi-functional system designed for survival. The tunnels are divided into temporary foraging routes and permanent living quarters. The foraging routes form an extensive network just below the root line for quick access to food.
The permanent section of the burrow system includes chambers excavated for specific needs. The nesting chamber is situated at the deepest point of the system for maximum protection and temperature stability. This chamber is lined with soft, dried grasses and leaves to house the voles and their young. Separate food storage chambers are also excavated off the main tunnel, located at a slightly shallower depth than the nest. These caches store roots, seeds, and other plant matter for later consumption, especially during colder months.