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Colorado State University Extension Managing Voles in Colorado Fact Sheet No. 6.507 Natural Resources Series 'Wildlife by W. F. Andelt, S. Ahmed and K. Jones* 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 (the long - tailed vole is an exception) and scantily haired tail. Eight species of voles are found widely throughout various ecosystems of Colorado, 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. *W.F. Andelt, Colorado State University Extension wildlife specialist and associate professor; and S. Ahmed, former graduate student; fishery and wildlife biology. Reviewed by K. Jones, Extension county director, (4 -H /Natural Resources /Agriculture) Chaffee /Park County. 6/2009 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 and garden crops. They also eat bark on trees and shrubs, especially during fall and winter. While they prefer young, succulent trees and plants, they can change their diet to meet their nutritional needs. Biology, Reproduction and Behavior Voles are active day and night throughout the year and do not hibernate. They usually live between two and six months. Their home ranges usually are less than one - fourth acre and vary with season, food supply and population density. Voles construct many surface runways and underground tunnels with numerous burrow entrances. A single burrow may contain several adults and young. Population densities of voles vary from species to species. Large population fluctuations that range from 14 to 500 voles per acre are common Their numbers generally peak every three to five years. Population is influenced by dispersal, food quality, climate, predation, physiological stress, and genetics. Voles have three to six young per litter and three to 12 litters per year. Their gestation period ranges from 20 to 23 days and they 10 ■ 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. © Colorado State University Extension. 11/95. Revised 6/09. www.ext.colostate.edu