Scientific Name: Microtus pennsylvanicus
Common Name: Meadow Vole
(Information for this species page was gathered in part by Ms. Melissa Alo for an assignment in Biology 220W, Spring 2006)
A “vole” is defined as a rodent belonging to the genus “Microtus.” Voles resemble rats and mice but have shorter tails and heavier, cylindrical bodies. The meadow vole (Microtus pennsylvanicus) (which is also called the “meadow mouse” or the “field mouse”) is 5 to 7 inches long including its tail. The tail is only as long as its hind legs. They weigh 1 to 2 ounces and have a body covered with coarsely textured hairs that have a range of colors from yellow-brown to reddish-brown to a dark, black-brown. The belly fur is lighter in color and is often silver or gray.
The meadow vole is the most widely distributed vole in North America. Its range extends from central Alaska eastward and south across Canada and the United States all the way to the east coast. New Mexico is the southwestern boundary (meadow voles are not found in the Rocky Mountain regions) and Georgia is its edge in the southeast.
Habitat and Territory
Meadow voles only live for 1 to 1½ years in the wild and hardly any longer in captivity. They inhabit a range of habitats from grassy fields (and lawns) to open woodlands and marshes. They are frequently found in shoreline zones along rivers, and around ponds and lakes.
Meadow voles (particularly females) establish relatively fixed home ranges over areas of 0.1 to 1.0 acres. Males, though, especially as they search for mates, tend to move quite freely from territory to territory. Movement of meadow voles throughout their habitat zones is an important aspect of their ecology. These movements enable dense, clumped populations to disperse evenly, generates an intense natural selection matrix via intraspecific competition for food and other resources, and also assists in the efficient mixing of genetic types (i.e. avoids inbreeding). The tendency of this species to “wander,” then, has some significantly positive consequences. Negative impacts of this behavior may include an increased risk of predation, but the “wandering” voles have been shown to have an overall higher rate of both survival and reproduction.
Meadow voles eat many different types of foods. In the spring and summer, they primarily consume living plants (grasses, sedges, plantain, and a wide variety of “weeds”). In the fall and winter, they switch over to grains, seeds, bark, roots, and over-wintering fruits (they are said to be very fond of cranberries). They must eat their body weight in food every day in order to survive. Since they do not hibernate and also do not store food, they are forced to actively forage every day of the year.
Meadow voles make nests of piles of mixed grasses, sedges, and “weeds.” These nests can be located either above or below ground. In the winter, a good snow cover is important for both thermal insulation and protective concealment. Radiating out from these nests are networks of shallow burrows through which the voles run in search of food. Meadow voles tend to be active at night during the summer and in the daytime during the winter.
Meadow voles are capable of rapid, explosive reproduction. A female meadow vole is reproductively mature at 20 days of age. Gestation (of litters that range from 2 to 11 pups) takes less than a month. Females may mate almost immediately after giving birth, and, so, after weaning one litter (which takes 21 days), she may then have another. It is possible for a female meadow vole to have 12 litters a year in areas of mild climate. In the more northern parts of their range, breeding “only” extends from March to November, and, so, a maximum of only 8 litters is possible.
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. The observation that meadow voles consume large numbers of the plants classified as “weeds” has led some to suggest that an active, balanced meadow vole population is of some ecological and economic benefit to both managed agricultural and lawn-grass ecosystems.
Predation and Disease
Many predators consume meadow voles. Hawks, owls, herons, crows, and blue jays along with skunks, weasels, cats, raccoons, and shrews all hunt and eat meadow voles. In addition, a wide variety of snakes (including black snakes and hognose snakes), snapping turtles, bullfrogs, and even largemouth bass eat this incredibly abundant prey species.
Meadow voles can carry a variety of potentially serious human pathogens. Toxoplasma gondii, Trypanosoma microti, rabies, Hantavirus, and Korean hemorrhagic fever are a few of the potential disease agents that have been detected in meadow vole individuals.
The meadow vole, then, is a small but significant component of our Nature Trail ecosystem. We seldom see it as we walk along the trail, but the healthy trees around us and the abundance of larger fauna that rely on the vole for food are all evidence of its importance and place in this ecosystem.