Voles: Identification, Habitat, Damage, Prevention, Control
Identification of VOLES
Meadow voles (also called meadow mice, field mice, etc.) belong to the genus Microtus.
We will simply refer to them as voles for the purpose of this article. Voles
are compact animals with stocky bodies, short legs and a short tail. Their eyes are
small and their ears partially hidden. Their under-fur is generally dense and
covered with thicker, longer guard hairs. They usually are brown or gray, though
many color variations exist. Seven species inhabit the 10 Great Plains states.
(See descriptions below) Tentative identification of a particular animal may be made
using species descriptions, habitat descriptions and range. For positive
identification (once the following vole descriptions have been exhausted) consult a
professional, such as your local County Agent. The following voles will be described
in this vole article:
Prairie Vole: The prairie vole is 5 to 7 inches long. Its fur is gray to dark brown mixed with gray, yellow or hazel-tipped hairs. This gives this particular vole a "peppery" appearance. Under-parts are gray to yellow-gray. This is the most common vole in prairie habitats, as its name implies. Top of page.
Meadow Vole: The meadow vole is the most widely distributed species in the United States. Its total length is 5 1/2 to 7 1/2 inches. Its fur is gray to yellow brown, obscured by black-tipped hairs. Northern subspecies may also have some red in their fur. The under-parts of the meadow vole are gray, at times washed with silver or buff. The tail of this vole is bicolored. Top of page
Long-tailed Vole: The long-tailed vole can be distinguished from other species by its tail which comprises 30% or more of its total length, which ranges from 6 to 8 1/2 inches. It has gray to dark brown fur with many black-tipped hairs. The under-parts are gray mixed with some white or yellow. The tail is indistinctly to sharply bicolored. Top of page
Pine or Woodland Vole: The pine vole is a small vole. Its total length is 4 to 6 inches. Its soft dense fur is brown. The under-parts are gray mixed with some yellow to cinnamon. The tail of this vole is barely bicolored or multi-colored. Top of page
Montane Vole: The Montane vole is 5 1/2 to 8 1/2 inches in total length. Its fur is brown, washed with gray or yellow mixed with some black-tipped hairs. Its feet are usually silver gray and body under-parts whitish in color. The tail of the Montane vole is bicolored. Top of page
Mexican Vole: The Mexican vole is a small vole, measuring 4 1/2 to 6 inches long. It has cinnamon brown fur, mixed with black hairs. Its under-parts are grayish yellow to cinnamon, sometimes mixed with silver white. The tail of the Mexican vole is unicolored or barely bicolored. Top of page
Water Vole: The water vole is the largest species in America. Its total length (from nose to tip of its tail) is 8 to 10 1/2 inches. It has grayish brown fur and gray under-parts washed with white or silver. The tail is bicolored -- dark above, light below. Top of page
Voles occupy a wide variety of habitats. They prefer areas with heavy ground cover including grasses, grass-like plants and litter. When two species of voles are found together in an area, they usually occupy different habitats. Though voles evolved occupying "natural" habitats, they also use habitats modified by man, such as orchards and cultivated fields. This is especially true when vole populations are high.
Prairie voles (as their name suggests) are the most common vole of the great Plains grasslands. It is found in a variety of habitats, such as old fields, marshlands, short grass prairies. When in association with the meadow vole, it is generally in drier habitats.
Meadow voles prefer wet meadows and grassland habitats. When in association with the Montane vole or prairie vole, it is generally in moister habitats.
Long-tailed voles are found in a wide variety of habitats such as sagebrush grasslands, forests, mountain meadows and banks of streams.
Pine voles (sometimes known as woodland voles) are found in a variety of habitats such as deciduous and pine forests, abandoned fields and orchards. Heavy ground cover is characteristic of these habitats.
Montane voles are found in alpine meadows, dry grasslands and sagebrush grasslands. It avoids forests. When in association with the meadow vole, it is generally in drier habitats.
Mexican voles are found in generally dry habitats and grassy areas such as mountain meadows and yellow pine forests.
Water voles are primarily found in semi-aquatic habitats. These areas include stream banks, lakeshores and in alpine meadows.
Voles may cause extensive damage to orchards and forests due to their girdling of seedling and mature trees. Girdling damage may also occur to ornamental plants. Girdling damage is most likely to occur in fall and winter. Field crops (such as alfalfa, clover, grains, potatoes) may be damaged or completely destroyed by voles. Crops are eaten and also damaged by the extensive runway an tunnel systems voles build. These runway and tunnel systems also interfere with crop irrigation by displacing water and causing levees and checks to wash out. Vole runway and burrow systems ruin lawns, golf courses and ground covers.
Voles are not a species which pose a major public health hazard because of their lack of contact with man. However, they are capable of carrying disease organisms transmissible to man, such as plague and tularemia; therefore, care should be taken when handling them.
An extensive surface runway system with numerous burrow openings is the most easily identifiable signs of voles. Runways are 1 to 2 inches in width. Vegetation near well-traveled runways may be clipped close to the ground. Feces and small pieces of vegetation are found in the runways.
Girdling an gnaw marks alone are not necessarily indicative of the presence of voles, since other animals -- such as jackrabbits -- may cause similar damage. Vole girdling can be differentiated from girdling by the lack of uniformity of the gnaw marks. They occur at various angles and in irregular patches. The approximate size is 1/8 inch wide, 3/8 inch long and 1/16 inch or more deep. Rabbits neatly clip branches with oblique clean cuts. Close examination of girdling damage and the presence of accompanying signs (feces, tracks, burrow systems, etc.) should enable identification of the animal causing girdling damage.
Cultural Methods and Habitat Modifications
Cultural and habitat modification practices can reduce the likelihood and severity of vole damage.
Weeds, ground cover and litter provide food and cover for voles. Eliminating them in and around crops, lawns and cultivated areas will reduce the capacity of these areas to support voles. Lawn and turf should be mowed regularly, and mulch, if used in orchards, cleared 3 feet or more from the base of trees.
Soil tillage is effective in reducing vole damage since it removes cover, destroys existing runway burrow systems and kills a percentage of the existing vole population. Because of tillage, annual crops tend to have lower vole population levels than perennial crops. It should be mentioned that voles nevertheless are capable of invading and damaging annual crops, especially those that provide them with cover for extended periods of time.
Repellents containing Thiram or a "hot sauce" type of ingredient are
registered for meadow voles. These products (as well as products registered for
other vole species) may afford short-term protection, but this has not been demonstrated
in many areas of the country.
Toxicants have been a mainstay in vole damage control. Zinc Phosphide has been the toxicant most frequently used. It is a single-dose toxicant available in pelleted formulation. Zinc Phosphide baits generally are broadcast at rates of 6 to 10 pounds per acre., or placed by hand in runways and burrow openings. Although pre-baiting (application of a non-toxic bait prior to applying toxic bait) is not usually needed to obtain good control, it may be required in some situations such as when a population has been baited several times and bait shyness has developed. ZP Gopher Bait is the best zinc Phosphide bait to kill voles.
Though voles rarely invade houses, when they do they can be controlled by setting snap
traps (see Victor Snap Traps
with expanded trigger) or live traps (the Tin Cat
is best) as you would for house mice. To protect non-target wildlife from injury,
you can use a combination of snap traps and Tin Cats. Simply place two snap traps
inside your Tin Cat, with triggers facing the entry holes. This prevents birds and
other wildlife from being hurt by the snap traps. Only mice and voles will be able
to enter the Tin Cat.
Shooting is not effective in controlling voles.