Tell Me More About Voles

Problems

The worst damage done by voles is associated with agricultural crops, and the operation of large orchards are most likely to suffer damage. Debarking of fruit trees occurs under the cover of snow and can be fatal when trees are completely girdled. Voles also feed on the roots of fruit trees, primarily during the winter. This spurt in damage may be a result of the diminished food supply during this dormant season. Apple tree roots contain more sugar and starch during the winter than any other season, possibly making them more attractive to voles. Moreover, in winter, voles spend more time close to their nests to avoid cold temperatures and predators. Because the nests are frequently located near tree trunks, roots are a convenient source of food. Typical vole damage occurs within the first decade after an orchard has been planted because as trees mature they are better able to sustain and fend off damage.

Voles will use mole tunnels to reach plant roots and bulbs and often cause damage for which moles erroneously are blamed. Homeowners may experience damage similar to agriculturalists but on a lesser scale. Fruit trees or shrubs, such as blackberries and raspberries, and occasional garden vegetables may be badly damaged or ruined. Plants in growing frames and greenhouses may be badly damaged, as might certain shrubs and bulbs in the ornamental garden.

Solutions

> Habitat Modification: The control of damage by voles should focus on the management of the habitat to make conditions less favorable for these animals. Populations can be reduced through soil cultivation; a tactic that destroys burrows, and reduces ground cover. Frequent, close mowing will reduce both cover and carrying capacity for these animals and is an important part of an integrated approach to population management.

Clearing vegetative debris from grassy areas adjacent to gardens and crops is a useful prevention measure. Clearing vegetation from a 3-foot radius around the base of a tree or shrub can force voles to relocate. However, because woodland voles remain below ground, this tactic may not affect their activities. In northern climates, snow may provide cover for voles at the time of year when plants are most likely to incur damage. Clearing snow away from the base of trees may be helpful when just a few need to be protected. Deep beds of mulch also encourage voles by facilitating their movement through tunnels created between the mulch and the ground. Reducing the layer of mulch to 1 to 2 inches may discourage voles.

Individual plants or flowerbeds can be partially protected with a subterranean barrier composed of hardware cloth (1/4-inch mesh or less) buried 6 to 8 inches into the soil. By sinking the barrier to a depth of at least 6 inches, the property owner will assure that animals do not burrow under the obstacle. This tactic may offer the best permanent solution to problems with voles in the residential yard. A barrier of gravel on paths also discourages voles from moving around yards because they prefer to excavate soft soil.

Tulips and hostas are favorite foods of voles and may occasionally sustain high damage. Homeowners whose plants are repeatedly assaulted by voles should consider substitute plants, such as daffodil, which are less palatable. Crown imperial is another showy plant that has a reputation for repelling voles. Plastic, metal, or cloth barriers may be wrapped around the trunks of individual trees to prevent voles from gnawing on their bark. Tar paper also is used for this purpose.

> Repellents: Voles can cause serious damage to ornamental flowerbeds by destroying the bulbs of plants such as lilies and tulips. Soaking bulbs before planting in one of the many commercially available bettering agents containing “Thiram” can be effective in limiting damage to new plantings.

Physical Appearance

Many people distinguish “meadow mice” from “field mice” by the fact that meadow mice (more properly called “voles”) have blunt snouts and short ears barely visible through the fur. Their ears and eyes are small relative to other mouse-like animals commonly seen. The physical feature that is most distinguishing is a short tail, which is less than 3 inches long. Most of the eight species of voles that make Colorado home are brownish in color, but the sagebrush vole is gray and the southern red-backed vole has a brick-red patch on its back. Size ranges from less than 6 inches long and 1-1½ ounces for sagebrush voles to about 7 inches long and up to 2½ ounces for meadow and prairie voles.

Habitat

Most species select habitats with good ground cover where their presence is revealed by runways, 1½ inches wide, often beneath a roof of thatch and littered with cut grass stems. Many voles also live in meadows, but the sagebrush vole lives in sagebrush and the Mexican vole in ponderosa pine savannah. Except for prairie uplands in the east and the southwestern desert valleys, most parts of Colorado support one or more species of voles.

Feeding Habits

Voles eat mostly plants: grasses, flowers, vegetables, fruits, bulbs and roots. They will also occasionally consume animal matter such as insects and snails. Red-backed and heather voles eat fungi, fruits, seeds and some leaves, but other voles mostly are grazers. Like other mammals that feed on abrasive grasses, they have ever-growing cheek-teeth that are continually replaced from below as the crowns wear away. In the winter, voles make tunnels beneath the snow, under the protection of which they gnaw the bark from trees and shrubs. They will also horde food in underground caches of as much as a gallon of stored nuts and berries.

Mating & Breeding

Like many small rodents, voles are short-lived but prolific breeders. In the wild, there can be 4 or 5 litters each summer, and even more in warm climates where breeding can occur year-round. Depending on the species and geographic region, the average litter size varies from 2 to 5 young. The young are born blind and helpless. Within three weeks of birth, females may begin breeding, with gestation a short 20 to 23 days. With this kind of reproduction potential, populations rapidly expand.

Predators

Voles are an important component in the diet of many predatory species including foxes, bobcats, snakes, and hawks. One of the best ways to ensure that other forms of control work well is to encourage natural predation. Predators do not, of course, eliminate prey species. Natural predation, however, can help keep numbers of animals, such as voles, down to a point where other management strategies become far more effective. Raptors can be particularly effective, and nesting boxes for barn owls and kestrels can encourage their presence. It is also possible to attract hawks and owls by erecting perches constructed of wood or metal and shaped into a “T” that will serve as observation posts to scan fields for voles and other small mammals.

Public Health

Voles are not considered to be a significant source for any infectious disease that can be transmitted to humans, companion animals, or livestock. They are known, however, to be the hosts for such communicable diseases as tularemia and bubonic plague.

- Information provided by the Colorado Division of Wildlife

- Information also provided by The Humane Society of the United States

Humane Society of U.S.| CO. Dept.of Health & Environment
Animal Control Home | Colorado Div. of Wildlife
Urban Wildlife Rescue | Table Mountain Animal Shelter