Voles are small, compact rodents, often mistaken for common mice, but distinguished by their shorter tails, stocky build, and partially hidden ears. Voles pose a significant threat to woody plants because they frequently consume both the bark and the roots of trees. This destructive feeding behavior is most pronounced when preferred food sources are unavailable, causing damage to landscaping and orchards, especially during winter when snow provides cover.
Vole Diet and Root Consumption
Voles are primarily herbivores, relying on grasses, seeds, tubers, and low-lying vegetation during the growing season. Their feeding habits shift dramatically in late fall and winter when above-ground plant material becomes scarce or covered by snow. At this time, the inner bark (cambium layer) and roots of trees become an energy source.
This consumption of bark around the trunk is known as girdling, which severs the tree’s circulatory system by disrupting the flow of water and nutrients. Two species are commonly implicated in tree damage: the meadow vole and the pine vole. Meadow voles typically girdle the trunk at or just above the soil line, or higher up under snow cover. Pine voles, which are more subterranean, cause significant root damage and girdle the root crown below the soil surface. They construct extensive tunnel systems just beneath the soil, accessing both fine feeder roots and larger structural roots. This underground feeding often leaves no obvious signs until the tree declines in health.
Recognizing Vole Damage to Trees
Identifying vole damage requires close inspection, as marks can be confused with those left by rabbits or gophers. Vole gnaw marks are characteristically small and irregular, often appearing in patches at various angles on the bark. The individual tooth marks are typically narrow, measuring about 1/8 inch wide and around 3/8 inch long, which is smaller than the cleaner, more uniform cuts left by rabbits.
The damage location is a strong indicator, as vole feeding is concentrated at the base of the trunk, at the soil line, or extending upward only as far as snow cover permitted. The presence of runways is a sign of meadow voles, who create shallow, worn paths about 1 to 2 inches wide through the grass and surface vegetation. These trails are used to navigate between burrows and feeding areas. Pine vole activity is harder to detect, but a spongy feel to the soil around the tree’s base indicates an extensive network of subterranean tunnels. Excavating the soil slightly may reveal girdling on the root crown or damage to the main roots, which may appear chewed or shaved.
Strategies for Protecting Trees
Protecting trees from voles involves two strategies: exclusion and habitat modification, both focused on making the area inaccessible or unattractive. Exclusion methods create a barrier around the vulnerable trunk and root crown. The most effective method is installing a cylinder made of 1/4-inch galvanized hardware cloth mesh around the tree trunk.
This barrier should extend at least 6 inches below the soil line to deter pine voles from burrowing, and up to 18 to 24 inches above the ground to protect against meadow voles feeding under snow. The cylinder must be a few inches wider than the trunk to allow for future growth and secured tightly to the ground. Installing this hardware cloth before the ground freezes offers the best protection for young and newly planted trees. Habitat modification removes the protective cover and food sources voles rely on near the tree. Maintaining a weed-free zone with a diameter of about four feet around the tree base eliminates both the food supply and concealment from predators. Keeping the surrounding grass mowed short also reduces vegetation height, discouraging voles from establishing surface runways. Exclusion and habitat management provide the most sustainable long-term defense for tree health.