142.

Prairie Vole

Microtus ochrogaster

French: Campagnol des Prairies / German: Prairiewihimaus / Spanish: Topillo de pradera

Taxonomy. Hypudadeus ochrogaster Wagner, 1843, America. Fixed by B. P. Bole, Jr. and P. N. Moulthrop in 1942 at “New Harmony, Posey County, Indiana,” USA.

Seven subspecies are recognized.

Subspecies and Distribution.

M. o. ochrogaster Wagner, 1843 — from extreme SE South Dakota, E Nebraska, E Kansas, and extreme NE Oklahoma E to SW Michigan, Indiana, Kentucky, Tennessee, and extreme NE Alabama, USA.

M.o.haydeniiBaird,1858—fromNEM.o.attheCanadianborderandNWNorthDakotaStoNENewMexicoandCOklahoma,USA.

M.o.ludovicianusBailey,1900—disjunctlimitedrangeontheSETexasandSWLouisianacoast,USA.

M.o.minorMerriam,1888—fromCAlbertaandCSaskatchewan,Canada,SEtoSESouthDakota,SMinnesota,andCWisconsin,USA.

M.o.ohionensisBole&M.o.,1942—WOhio,EKentucky,andWWestVirginia,USA.

M.o.similisSeveringhaus,1977—fromCM.o.StoCWyomingandextremeSWSouthDakota,USA.

M. o. taylori Hibbard & Rinker, 1943 — SW Kansas and extreme NW Oklahoma, USA.

Descriptive notes. Head-body 106-131 mm, tail 24-41 mm, ear 11-15 mm, hindfoot 17-22 mm; weight 37-48 g. Sexual dimorphism is minimal. Dorsal fur of Prairie Voles has coarse, relatively long hairs that are grayish brown to dark bister (brownish yellow) and grizzled. Venter is neutral gray or washed with white or pale cinnamon. Wild and captive color variants include blonde, silver, smoky, melanistic, albinistic, and white-spotted. Females have three pairs of mammae, and flank glands are poorly developed. M, has three transverse loops and no closed triangles; M” has two closed triangles. Dental formula is I 1/1,C0/0,P0/0,M 3/3 (x2) = 16. Chromosomal complementis 2n = 52 or 54, FN = 64.

Habitat. Grassland habitats and frequently agriculturalfields.

Food and Feeding. Prairie Voles eat grasses, forbs, and occasionally shrubs and trees. Common plants consumed include a variety of herbs and grasses ( Andropogon, Bouteloua, Bromus, Dactylis, Festuca, Poa, and Sporobolus, all Poaceae). When found in agricultural or suburban settings, they can cause major harm to young, planted trees, including pines ( Pinus spp., Pinaceae). Plants can be cached underground.

Breeding. Prairie Voles breed year-round, but activity is greatest in May—October and lowest in December—January. Prairie Voles are considered monogamous; male-female pairs form strong bonds and provide equal care of young.

Activity patterns. Prairie Voles are active throughout the year and day . Activity patterns are influenced by weather conditions. On hot days, they tend to be more active in evening and at night; during cold periods, they are more active diurnally. In captivity, peak activity is before midnight.

Movements, Home range and Social organization. Prairie Voles build extensive runways systems, and suitable cover for runaways is a critical habitat requirement. Each runway has a long, meandering main branch, with numerousside branches. Subterranean nests and food caches—some more than 2 m deep—are associated with these runways. Nests can also be found under boards or logs. Availability of food and abiotic factors are thought to be key drivers of recorded population cycles. Although long thought to be distinct cycles, long-term population studies suggest a lack of regularity. Density of runwaysis correlated with density of Prairie Voles and might be important in individual spacing and avoidance. Lowest survivorship of males occurs during increasing and peak phases of population change. Young Prairie Voles exclusively use ultrasonic vocalizations, but adult males also use them to possibly communicate reproductive availability. Prairie Voles are important prey for various predators.

Status and Conservation. Classified as Least Concern on The IUCN Red Lust.

Bibliography. Batzli et al. (1977), Bole & Moulthrop (1942), Caire et al. (1989), Getz et al. (1987), Hall (1981), Krebs et al. (1969), McGuire et al. (1993), Musser & Carleton (2005), Reed & Choate (1988), Stalling (1990).