Voles are mouse like rodents somewhat similar in appearance to pocket gophers. They have a compact, heavy body, short legs, short-furred tail, small eyes, and partially hidden ears. The long, coarse fur is blackish brown to grayish brown. When fully grown they can measure 5 to 8 inches long, including the tail. Eastern meadow voles look like mice with tiny ears and short tails.
Voles spend most of their time below ground in their burrow system. The clearest signs of their presence are the well-traveled, aboveground runways that connect burrow openings; the runways are usually hidden beneath a protective layer of grass or other ground cover. The maze of runways leads to multiple burrow openings that are each about 1-1/2 to 2 inches in diameter.
Voles are active day and night, year-round. They are normally found in areas with dense vegetation. Voles dig many short, shallow burrows and make underground nests of grass, stems, and leaves. In areas with winter snow, voles will burrow in and through the snow to the surface.

Quick Facts...
• Eight species of voles are found in Colorado. They often are called meadow, field or pine mice.
• Voles are small mammals that cause damage by girdling seedling and mature trees in orchards, shelterbelts and forests. They also damage field Crops and frequently construct runways in lawns.
• Damage by voles can be reduced by habitat modification, exclusion, repellents, trapping, and poison grain baits.
Introduction
Voles are small rodents that measure 4 to 8.5 inches long and weigh 0.8 to 3 ounces and vary in color from brown to gray. They are pudgy, with blunt faces and small eyes, small and sometimes inconspicuous ears, short legs, and a short and scantily haired tail (the long-tailed vole is an exception). .

Eight species of voles are distributed widely throughout various ecosystems of Colorado. They often are found in heavy ground cover of grasses, grass-like plants, and litter. Southern red-backed voles (Clethrionomys gapperi) are found in moist and well-developed coniferous forests. They are most abundant in lodgepole pine (Pinus contorta) stands, usually between 8,000 and 11,000 feet.
Meadow voles (Microtus pennsylvanicus) primarily occur along the Front Range and southcentral Colorado. They tend to live in or near damp marshy areas or wet meadows. Montane voles (Microtus montanus) primarily are found in the western half of Colorado in moist meadows and valleys and in grassy areas from 6,000 feet to above timberline. Long-tailed voles (Microtus longicaudus) occur just below 5,000 feet elevation to above timberline in the western half of Colorado. They are most abundant in streamside meadows. Mexican voles (Microtus mexicanus) are associated with grassy areas of Ponderosa pine (Pinus ponderosa) forests of southwest Colorado in Mesa Verde National Park. Prairie voles (Microtus ochrogaster) are found along streams and irrigated lands in northeastern Colorado. Sagebrush voles (Lemmiscus curtatus) occupy the driest of all vole habitats in Colorado. They occur between 5,000 and 9,000 feet in the northwest. Heather voles (Phenacomys intermedius) are found from 7,000 to 12,000 feet in the forested mountains of central Colorado. They occupy a variety of habitats but are most abundant along streams.
Voles eat a variety of grasses, forbs and agricultural Crops. They also eat bark on trees and shrubs, especially during fall and winter.
Voles are small, weighing one to two ounces as adults. Their overall adult body length varies from three to five and one-half inches in the pine vole, to about four and one-half to seven inches in the meadow and prairie voles.
Voles are an important food source for many predators, including snakes, hawks, owls, coyotes, weasels, foxes, mink and badgers. Mortality rates for voles are very high. Life expectancy in the wild often does not exceed two months, and few ever live longer than 16 months. Not surprisingly, voles are very prolific animals, although the pine vole is less so than meadow or prairie voles.
The breeding season for all voles encompasses most of the year although peaks occur in spring and fall. Prairie and meadow voles normally have five to 10 litters per year and average three to five young per litter. Pine voles have one to six litters per year and average two to four young per litter. The gestation period is about 21 days. One meadow vole held in captivity had 17 litters during one year, totaling 83 young. One of the females from her first litter had 13 litters, totaling 78 young before she was one-year-old.
Prairie and meadow voles inhabit pastures, roadsides, alfalfa fields and other grassy or weedy sites. Preferred habitats include areas with fairly dense ground vegetation. Meadow voles are more common in low, moist areas or upland sites near water.
Pine voles live in timbered areas, underground or under the forest litter. They also inhabit fields surrounding timber, if enough ground cover is present.
Prairie and meadow voles construct surface runways that are easy to recognize by the closely clipped vegetation within them. Small holes lead to underground runways and nesting areas. Pine voles have extensive underground runway systems, and spend little time above the leaf litter and ground cover layer.
Probably the most extensive and costly damage caused by voles occurs to woody plants in winter. At times voles severely damage or kill many young trees and shrubs, including orchard, windbreak and landscape plantings. Voles will eat the green inner bark layer of trees and shrubs when preferred foods are unavailable. Voles can damage or consume flower bulbs, garden plants and vegetables, field crops and forage crops. Two of their favorite foods are hostas and tulips. Voles can damage lawns by constructing runways and clipping grass very close to the roots. Though the damage done usually is not permanent, it may detract from the appearance of a well-kept lawn.

Damage and Control
Voles can cause extensive damage to forests, orchards and ornamental plants by girdling trees and shrubs. They prefer the bark of young trees but will attack any tree, regardless of age, when food is scarce. Monitor orchards frequently so control measures can be implemented before appreciable damage occurs. Most damage occurs in the winter when voles move through their grass runways under the protection of snow. The greatest damage seems to coincide with years of heavy snowfall.