Voles are small, mouse-like rodents that cause significant damage to lawns, gardens, and landscaping across Colorado. These pests, sometimes called meadow mice, are herbivores that feed on vegetation, often destroying root systems and girdling trees and shrubs. Vole populations can increase rapidly throughout the year, making effective management necessary. Protecting your property requires understanding the specific signs of infestation and implementing a combination of exclusion and active removal methods.
Confirming the Infestation: Vole Identification and Damage
Voles are often confused with moles or gophers, but their physical characteristics and damage patterns are distinct. A vole is a compact rodent with a stocky body, a blunt nose, small eyes, and a short tail that is typically less than half the length of its body. Moles create raised, volcano-shaped soil mounds or surface ridges as they tunnel for insects, and gophers create crescent-shaped mounds of soil with a plugged entrance hole. The most recognizable sign of a vole is an extensive network of surface runways in the grass. These narrow, clipped pathways, about one to two inches wide, connect feeding areas and small, clean burrow openings often hidden beneath mulch or dense vegetation. Damage appears as irregular gnaw marks (1/16 to 1/8-inch wide) on the bark of trees and shrubs, usually near the ground or under the snow line. This process, known as girdling, can completely circle the trunk, often killing the plant.
Habitat Modification and Exclusion Strategies
Managing the environment is the first step in making your property less attractive to voles. Voles thrive in areas with dense vegetative cover, which offers protection from predators like hawks and owls. Eliminating this cover is an effective preventative measure, starting with close mowing of turf areas and removing weeds, heavy mulch, and debris piles. Keep mulch beds thin and pulled back at least three feet from the base of vulnerable trees and shrubs. Reducing their food supply also helps, which includes promptly harvesting fallen fruits and minimizing spilled birdseed near feeders. To protect individual plants, physical barriers offer a reliable exclusion method, especially for young trees and high-value shrubs susceptible to winter girdling damage. Cylinders made of hardware cloth (ΒΌ-inch mesh or less) should be placed around the trunk. These barriers must extend at least 18 inches above the soil line and be buried six inches deep to prevent voles from burrowing underneath.
Active Removal Methods for Colorado Properties
Trapping
When habitat modification is not enough, active removal is necessary. Trapping is the most practical and effective method for homeowners. Mouse-sized snap traps are recommended and should be set perpendicular to the runways with the trigger end placed directly in the path of travel. While voles often activate the trap simply by running over the trigger, baiting with apple slices, peanut butter mixed with rolled oats, or sunflower seeds can increase success. To protect non-target animals, cover the set snap traps with a small box or shingle that has entry holes. For active infestations, multiple traps, sometimes ten or more, should be set and checked twice daily for immediate removal and resetting. Trapping is most successful in the fall and winter when natural food sources are scarce, making the bait more appealing.
Repellents
Repellents are another option, though their effectiveness is often uncertain and temporary, requiring repeated applications, especially after precipitation. Repellents containing ingredients like castor oil or capsaicin work by making the treated area unpalatable or unpleasant for the voles. They are best used as a deterrent to prevent re-infestation after a population has been reduced through trapping, but they should not be relied upon for initial control.
Rodenticides
The use of poison grain baits, known as rodenticides, is an option for large infestations, but it requires extreme caution, particularly in Colorado. Zinc phosphide is the most common toxicant used for voles in the state, but it is extremely toxic and poses a high risk to children, pets, and non-target wildlife. Because voles are a primary food source, the use of rodenticides can lead to secondary poisoning of predators such as raptors, foxes, and coyotes, which are beneficial to the ecosystem. Homeowners must carefully read and follow all label instructions, as regulations on pesticide use are strictly enforced by the Colorado Department of Agriculture. This includes understanding the specific application methods required to minimize risk to non-target species.