ANR-1146, New March 1999. Jim Armstrong, Extension Wildlife Scientist, Associate Professor, Zoology and Wildlife Science, Auburn University

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Controlling Voles

One day your small tree appears healthy, and the next day it is dead; one day your flower garden is beautiful, and the next day the plants are wilted and dying. Closer inspection reveals tiny teeth marks around the plant at ground level or the root system is gone! What animal could wreak such damage in such a short time? The vole!

There are two species of vole native to Alabama--the pine or woodland vole (Microtus pinetorum) and the prairie vole (Microtus ochrogaster). The prairie vole is uncommon in Alabama and lives only in the northern third of the state. However, the woodland vole is quite common and is found statewide in, as the name implies, woodlands. In this publication, voles are referred to in the generic sense only.

Voles are small rodents (4 to 6 inches long) with short legs, short tails, small eyes, and small ears (Figure 1). The preferred habitat of voles is quite varied but typically includes areas with heavy ground cover. These areas may include natural habitats as well as orchards, fields, and gardens. Voles are primarily herbivores that feed on grasses and forbs. On occasion, they may eat tree bark. They are active day and night, searching for food in a home range of about 1/4 acre. They seldom venture into exposed places, using instead elaborate tunnel systems in which they can travel safely.

Figure 1. Vole

Populations of voles fluctuate from year to year and seem to be somewhat cyclic, with peaks ranging from every 2 to every 5 years. During these peak population cycles, the density of voles may become quite high. Voles breed throughout the year and may have one to five litters of three to six offspring each time. These animals reach sexual maturity in 35 to 40 days. Thus, populations can expand rapidly, and areas that had no damage may suddenly experience severe damage. Voles do have a high mortality rate, and life-spans are only 2 to 16 months.

Identifying Vole Damage

Voles may chew roots or girdle the main stem of a plant. Vegetable gardens, ornamental plantings, and young forest stock are all susceptible to damage by voles. The most obvious sign of vole damage is a dead or dying plant. Voles may tunnel adjacent to root systems and eat roots below the ground. In addition, where protective cover is available, voles may chew or girdle the main stem just above the ground (Figure 2).

Figure 2. Vole damage

Vole damage may be confused with rabbit damage or mole tunneling. If plants are dying, look at the gnawing or chewing pattern to distinguish between vole damage and rabbit damage. Voles have small teeth that will leave small, irregular gnaw marks at various angles on the plant. Rabbits have wider teeth and therefore leave wider marks. In addition, rabbits will often completely cut the plant in two with a uniform 45-degree-angle cut (Figure 3).

Figure 3. Cut made by rabbit (45-degree cut end)

Many people have vole damage and blame it on moles. Moles eat insects, earthworms, and grubs and make the familiar raised tunnel system in lawns. Voles feed on plant material and have underground burrows. Moles seldom cause extensive plant damage. If plants are being eaten, the culprit is a vole, not a mole. It is important to distinguish between the two types of animal activity because control efforts for voles will not stop mole activity and vice versa.

Controlling Voles

Voles generally do not like to venture into open territory; therefore, modifying the habitat by eliminating ground cover can be effective in reducing vole damage. Keeping lawns adjacent to flower gardens mowed to a short height may help discourage voles from moving into gardens to feed. Minimizing the amount of mulch in flower gardens and turning the mulch frequently may help discourage voles from establishing tunnel systems. Mulch rings or mounds should be cleared back a minimum of 3 feet from the base of trees. Tilling soil in agricultural settings destroys the tunnel systems and is therefore useful in reducing vole populations and subsequent damage.

Trapping voles in large-scale operations is not cost effective. However, where voles are a problem in flower gardens or small vegetable gardens, trapping may be useful. Mouse snap traps can be placed at the entrances to tunnels or runways. Bait the trap with a mixture of peanut butter and oatmeal or sliced apples, and place it so that the trigger faces the tunnel mouth.

There are no toxicants currently registered for vole control in Alabama. Fumigants are generally ineffective due to the expansive tunnel system associated with vole activity.

Voles have extremely high reproductive potentials; thus, it is doubtful that predators alone could prevent vole damage. However, snakes, hawks, owls, and other predators will feed on voles if afforded the opportunity.

Vole damage to ornamental gardens and vegetable gardens does not constitute a serious economic threat. However, to those experiencing damage, the damage may be quite severe and warrant control by habitat modification and trapping. As is usually the case, a combination of control methods produces the best results.

For more information, contact your county Extension office. Look in your telephone directory under your county's name to find the number.