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Voles, Both The Good and The Bad

Prairie Vole (Microtus ochrogaster)

Color: Brown (light or dark) back; white or silvery belly
Body Length: 3-7 inches
Tail Length: 0.5–1.5 inches
Communication: Auditory, Chemical
Diet: Roots and other parts of clovers, dandelions, alfalfa, penstemon, ambrosia, and goldenrod
Mating System: Monogamous
Lifespan: 1-1.5 years

Voles are small, chunky, ground-dwelling rodents. Mature voles are 5 to 7 inches long and have stocky bodies, short legs, and short tails. Adults are chestnut-brown mixed with black, and their underparts are dark gray. The underfur is generally dense and covered with thicker, longer guard hairs. Their feet are brownish, and the thin hair that covers their tails is dark on the upper surface, gradually changing to a lighter gray beneath. They have small black eyes, and their ears are furred and do not project much above the hair.

Voles are frequently mistaken for moles, shrews, and mice. Moles have greatly enlarged front feet, with prominent digging claws. Moles also have no external ears and very small eyes. Shrews are smaller than voles, and have long, pointed snouts and pointed front teeth, with their eyes and ears nearly hidden in their fur. Voles have rounded, blunt snouts, and their front teeth are chisel-shaped. Their eyes and ears are readily apparent. The distinction between voles and mice is less obvious. The best way to distinguish them is by tail length. Mice have long tails that extend nearly half their body length, whereas voles have short tails.

Wisconsin Vole Species

Graphic of Vole anatomy There are 3 vole species native to Wisconsin: Woodland Vole (Microtus pinetorum), Prairie Vole (Microtus ochrogaster) and Meadow Vole (Microtus pennsylvanicus).

Woodland Vole

Woodland voles are common in old fields, thickets, gardens, orchards, and the edges of agricultural land, particularly where the soil is loose and sandy.

Prairie Vole

Prairie voles live in grassy fields that are not too damp. They prefer pastures, alfalfa fields, prairies, and weedy areas. Near towns they live on golf courses and vacant lots.

Meadow Vole

The meadow vole is most often found in extensive grassy or weedy areas such as old fields and moist hillsides with heavy ground cover. However, stream and pond banks, orchards, pastures, hay fields, and fence rows also provide suitable habitat for meadow and woodland voles. Meadow voles occasionally invade lawns, gardens, and nurseries.

Family Life

Woodland Vole (Microtus pinetorum) Voles are semifossorial, and as such, construct many tunnels and surface runways with numerous burrow entrances. A single burrow system may contain several adults and young. Vole nests are globular structures of dry grass about 6 to 8 inches in diameter. Nest cavities are usually located on the surface of the ground or under old boards, discarded metal, logs, or other such cover. In winter, above-ground nests may be made in deep snow, but these are temporary and will be vacated when the snow melts.

Voles may breed throughout the year, but most commonly in spring and summer. Generally, they have 1 to 5 litters per year. Litter sizes range from 1 to 11 young, but usually average 3 to 6 young. The gestation period is about 21 days. Young are weaned by the time they are 21 days old, and females are sexually mature in 35 to 40 days. Voles have short lifespans that generally range from 2 to 16 months.

Large population fluctuations are characteristic of voles. Population levels generally peak every 2 to 5 years; however, these cycles are not predictable. Extremely high vole densities sometimes can occur during population irruptions. Food quality, climate, predation, physiological stress, and genetics have been shown to influence population levels.

Diet

 Meadow Vole (Microtus pennsylvanicus) Voles eat a wide variety of plants, most frequently grasses and forbs. In late summer and fall, they store seeds, tubers, bulbs, and rhizomes. They eat bark at times, primarily in fall and winter, and will also eat grain crops, especially when their populations are high. Occasional food items include snails, insects, and animal remains. Voles are active day and night, year-round, with peak activity occurring at dawn and dusk. They do not hibernate. Their home range is usually ¼ acre or less, but this range varies with season, population density, habitat, and food supply.

The Good

The impacts of meadow voles on their ecosystems are significant. Their high rate of ingestion of vegetable materials stimulates its decomposition and nutrient release. Their nutrient rich fecal pellets are widely dispersed through their habitats to the great benefit of new and growing vegetation. These voles also accelerate the dispersal of vital mycorrhizal fungi, and, thus, influence the survival and growth rates of many important species of trees. Meadow voles are most abundant in the open field and shrub ecosystems of early successional stages of disturbed ecosystems. Their presence and activities greatly influence the rate and direction of subsequent successional stages.

Voles are also an important part of the food chain, serving as prey for many predators such as hawks, owls, snakes, weasels, raccoons, foxes, opossums, and house cats.

The Bad

Lawn damage by voles Voles may cause extensive damage to orchards, ornamentals, and tree plantings by gnawing on the bark of seedlings and mature trees (girdling). They eat crops outright and also cause damage by building extensive runway and tunnel systems through crop fields. Underground, woodland voles may consume small roots, girdle large roots, and eat bark from the base of trees.

Here are several ways to control vole populations to prevent garden damage.

Exclusion

Wire guards made of ¼-inch hardware cloth will help prevent meadow vole damage to small trees and shrubs. Wire cylinders 18 to 24 inches high set into the ground around the trunk will prevent meadow voles from girdling the tree.

Habitat Modification

Eliminating weeds, ground cover, and litter is an excellent method of achieving long-term control of voles. Repeated mowings that maintain ground cover at a height of 3 to 6 inches reduce both food and cover and expose voles to predators. Therefore, lawn and turf should be mowed regularly.

If voles are damaging trees, clear all mulch 2 feet or more from the bases of trees. Establishing vegetation-free zones that extend at least 2 feet from tree trunks under tree canopies will discourage voles from living near the bases of trees, where they cause the most damage

Frightening

Agents designed to frighten rodents are not effective in reducing vole damage.

Repellents

Repellents containing thiram (a fungicide) or capsaicin (the ingredient that makes chili peppers hot) are registered for vole control. Little data is available on the effectiveness of repellents to deter vole damage. Therefore, repellents should not be used as the sole method of vole control.

Trapping

Although not effective on a large scale, trapping is the safest way to remove voles in home grounds or small orchards before vole numbers are extremely high. Fall and late winter are periods when voles are easiest to trap. Set mouse-sized snap traps at burrow openings or in runways near ornamental shrubbery, flower beds, gardens, or rock walls. Bait the traps with a peanut butter-oatmeal mixture or apple slices. Set the trap perpendicular to the runway, and cover the trap with an inverted cardboard box or pan. Be sure to allow space for the trap to operate freely under the covering.

Further Information on Garden Pests

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 All About Aphids and Their Control
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