(c) 2003 John White

What is a vole doing in my yard?

These small, short-tailed, brown or gray rodents are active year-round, but you're likely to see them only infrequently: they spend most of their time in burrows below ground. Especially during the peaks of their three- to five-year population cycles, voles are drawn to gardens and landscapes with deep mulches and litters and with dense, tall grasses and weeds. They tend to spend their entire-though brief-lives in an area smaller than a quarter acre. They can have five or more litters a year, with about three to six young per litter.

Unlike pocket gophers, whose burrows are distinguishable by significant above-ground damage, voles leave few visible signs. They reveal their presence by the narrow, aboveground, grassy runways they use between their small burrow openings; look close and you're likely to see grass clippings and small green droppings in the runways.

Benefits and conflicts

Voles can eat snails and insects, but that may not be enough to endear them to gardeners. In addition to temporarily damaging the turf in their runways by clipping it very close to the roots, voles feed on many different kinds of grasses, herbaceous plants, bulbs, and tubers. In the vegetable patch, they favor artichokes, beets, Brussels sprouts, cabbage, carrots, cauliflower, celery, lettuce, turnips, sweet potatoes, spinach, and tomatoes. In fall or late winter, they turn to the bark and roots of trees and shrubs, which they can damage significantly.

Strategies for coexistence and control

Habitat modification: Keep grasses mowed and remove weedy patches at your garden's edge. Clear a 3- to 4-foot circle around the base of young trees or vines: voles don't like to feed where they can be seen. Minimize spillage from bird feeders.

Fencing: Fortunately, voles don't climb well. They can be thwarted by a fence made of 1/4-inch or smaller mesh that's about 12-18 inches aboveground and 6-10 inches below ground. Similarly, cylinders made of _-inch or smaller hardware cloth, sheet metal, or heavy plastic (sunk into the ground as deeply as possible without damaging plant roots) will protect young trees, vines, and ornamentals. Check these cylinders frequently to make sure the voles haven't dug under them.

Frightening devices and repellents: Frightening devices are ineffective against voles and repellents offer only short-term effectiveness. Available poisons can be toxic to humans and pets as well as to nontarget wildlife.

Trapping: You can trap small populations of voles with mouse traps baited with a peanut butter-oatmeal mix. Set the traps at right angles to the runways, with the trigger ends in the runways. To reduce access by nontarget birds and other animals, cover the traps with a box through which you've cut a 1-inch hole or enclose the traps in PVC pipe. Check the traps daily; because voles can carry infectious disease organisms or parasites, be sure to handle their remains with rubber gloves or similar protection.

For more information

How to Manage Pests in Landscapes and Gardens: Voles (Meadow Mice), University of California Statewide Integrated Pest Management Program, http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7439.html

Managing Voles in Colorado, Colorado State University Extension, http://www.ext.colostate.edu/Pubs/natres/06507.html

top