The eastern meadow vole (Microtus pennsylvanicus), sometimes called the field mouse or meadow mouse, is a North American vole found in eastern Canada and the United States. Its range extends farther south along the Atlantic coast.
The western meadow vole, Florida salt marsh vole, and beach vole were formerly considered regional variants or subspecies of M. pennsylvanicus, but have all since been designated as distinct species.
The eastern meadow vole is active year-round, usually at night. It also digs burrows, where it stores food for the winter and females give birth to their young. Although these animals tend to live close together, they are aggressive towards one another. This is particularly evident in males during the breeding season. They can cause damage to fruit trees, garden plants, and commercial grain crops.
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The meadow vole is a small mammal and is one of 26 other rodent species native to North America called voles.-->
Taxonomy
The species was formerly grouped with the western meadow vole (M. drummondii) and the Florida salt marsh vole (M. dukecampbelli) as a single species with a very large range, but genetic evidence indicates that these are all distinct species.
Distribution
The eastern meadow vole is found throughout eastern North America. It ranges from Labrador and New Brunswick south to South Carolina and extreme northeastern Georgia; west through Tennessee to Ohio. West of Ohio, it is replaced by the western meadow vole. Several subspecies are found on eastern islands, including the beach vole (M. p. breweri) and the extinct Gull Island vole. In Virginia, eastern meadow voles were least abundant in eastern red cedar (Juniperus virginiana) glades and most abundant in fields with dense grass cover.
Habits
Eastern meadow voles are active year-round and day or night, with no clear 24-hour rhythm in many areas. Most changes in activity are imposed by season, habitat, cover, temperature, and other factors. Eastern meadow voles have to eat frequently, and their active periods (every two to three hours) are associated with food digestion.
thumb|right|Juvenile in the open
Patterns of mortality apparently vary among eastern meadow vole populations. The average eastern meadow vole lifespan is less than one month because of high nestling and juvenile mortality. and post-nestling juveniles had the highest mortality rate (61%), followed by young adults (58%) and older age groups (53%). Nestlings were estimated to have the lowest mortality rate (50%). Estimated mean longevity ranges from two to 16 months. Breeding often ceases in January and starts again in March. Eastern meadow voles in optimal habitats in Virginia (old fields with dense vegetation) reached densities of 983/ha (398/ac); populations declined to 67/ha (27/ac) at the lowest point in the cycle. Above the threshold amount, the quantity of cover influences the amplitude and possibly the duration of the population peak. Local patches of dense cover could serve as source populations or reservoirs to colonize less favorable habitats with sparse cover. Eastern meadow voles are most commonly associated with sites having high soil moisture. They are often restricted to the wetter microsites when they occur in sympatry with prairie voles (Microtus ochrogaster) or montane voles.
In West Virginia, the only forested habitats in which eastern meadow voles were captured were seedling stands.
In Pennsylvania, three subadult eastern meadow voles were captured at least 1.6 miles (2.6 km) from the nearest appreciable suitable eastern meadow vole habitat, suggesting they are adapted to long-distance dispersal.
In Ohio, the effects of patch shape and proportion of edge were investigated by mowing strips between study plots. The square plots were 132 feet per side (40 m x 40 m), and the rectangular patches were 52.8 feet by 330 feet (16 m x 100 m). Square habitat patches were not significantly different from rectangular patches in eastern meadow vole density. Edge effects in patches of this size were not found, suggesting eastern meadow voles are edge-tolerant. Habitat patch shape did affect dispersal and space use behaviors. In rectangular patches, home ranges were similar in size to those in square patches, but were elongated.
Eastern meadow voles tend to remain in home ranges and defend at least a portion of their home ranges from conspecifics. Home ranges overlap and have irregular shapes.
Cover requirements
Nests are used as nurseries, resting areas, and as protection against weather. They are constructed of woven grass; they are usually subterranean or are constructed under boards, rocks, logs, brush piles, hay bales, fenceposts, or in grassy tussocks. Eastern meadow voles dig shallow burrows,
Predators
Eastern meadow voles are important prey for many hawks, owls, and mammalian carnivores, and are also taken by some snakes. and in Wisconsin, eastern meadow voles comprised 95% of short-eared owl (A. flammeus) prey. Most mammalian predators take microtine prey.
Management
Eastern meadow voles are abundant in agricultural habitats. The list of crops damaged by eastern meadow voles includes root and stem crops (asparagus, kohlrabi), tubers, leaf and leafstalks, immature inflorescent vegetables (artichoke, broccoli), low-growing fruits (beans, squash), the bark of fruit trees, pasture, grassland, hay, and grains.
Management of eastern meadow vole populations in agricultural areas includes reduction of habitat in waste places such as roadsides and fencerows by mowing, plowing, and herbicide application. Predators, particularly raptors, should be protected to keep eastern meadow vole populations in check. Direct control methods include trapping, fencing, and poisoning; trapping and fencing are of limited effectiveness. Poisons are efficient. Repellents are largely ineffective at present. Properly timed cultivation and controlled fires are at least partially effective in reducing populations.
Ecto- and endoparasites have been reported to include trematodes, cestodes, nematodes, acanthocephalans, lice (Anoplura), fleas (Siphonaptera), Diptera, and ticks and mites (Acari).
Ecological importance
As with many other small mammal species, M. pennsylvanicus plays important ecological roles. The eastern meadow vole is an important food source for many predators, and disperses mycorrhizal fungi. It is a major consumer of grass and disperses grass nutrients in its feces.
Threats
While it is a common and wide-ranging species throughout eastern North America, insular populations on the eastern periphery of the species' range are at risk from invasive species, with the extinction of the Gull Island vole being a notable example of this. In addition, due to its dependence on mesic habitats, populations of the species on the mainland periphery of its range in the Southeastern United States may be at potential risk from climate change-induced aridification.