Although 8 species of voles inhabit the state of Colorado, the primary activity along the Front Range and south central Colorado is attributed to the meadow vole. Often called meadow or field mice, these small rodents are known for creating runways in lawns, girdling trees and shrubs and causing general damage to ornamental type plants around homes and businesses. Voles vary in size and colors based on their species, but are generally 4-8.5 inches in length and weigh roughly 1-3 ounces. Colors vary from brown to gray. They are typically thick bodied with a shortened face and small eyes. Their legs are short as well as their tails (with the exception of the long-tailed vole).
Meadow voles tend towards moist areas; however, they will readily make themselves at home in lawns and gardens. Voles consume grasses and garden crops during spring and summer months followed by bark from trees and shrubs in the cooler months. They have the capability to cause significant amounts of damage and diets typically fluctuate to meet their nutritional needs. Although voles have a fairly short average life span of two to six months due to predation, availability of food and extermination by humans, reproduction can occur rapidly with up to twelve litters single year ranging from 3-6 young per litter. Females are mature enough to become pregnant at a mere three weeks of age. Voles are active year round and do on hibernate. Many species of voles are diurnal and therefore are active both day and night.
Vole damage may be mistaken for rabbit damage when it comes to stems and girdling of trees and shrubs. Gnaw marks created by voles will be narrow, typically only 1/16 to 1/8 of an inch. Girdling may include the trunk as well as roots of trees and shrubs. When roots are girdled, trees often take on the appearance of being diseased or insect infested. Stems of plants damaged by voles will often have a pointed tip versus the usual 45 degree angle when rabbits are present or the roughened edges left by deer. Vole runways in lawns are characterized as one to two inches in width and tend to run through areas where the grass and/or weed cover is dense or matted. Soil in areas surrounding burrows may be soft or spongy.
Controlling voles can be difficult and methods have varied success. Repellents are manufactured to protect trees and shrubs as well as some vegetable crops from the damaging effects of voles; however, limited information is available as to the effectiveness of these products. Trapping in large areas is typically not recommended or considered to be efficient as it can be time consuming. Rodenticide applications, habitat modification and exclusion techniques often provide the most effective control for voles. Keeping lawns mowed short decreases coverage for voles and may discourage activity. Exclusion methods often include fine mesh hardware cloth along fencing in an “L” shape buried, extending away from the fence line surrounding gardens and around the bottoms of trees and shrubs. Rodenticide applications are, in general, applied to burrows and runways to encourage feeding and decrease non-target consumption. Pest pressure from surrounding properties should also be considered when determining the best control methods for voles.