149.

Meadow Vole

Microtus pennsylvanicus

French: Campagnol des prés / German: Wiesenwhimaus / Spanish: Topillo de campina

Other common names: Admiralty Island Meadow Vole (admiraltiae), Block Island Meadow Vole (provectus), Chihuahua Vole (chihuahuensis), Penobscot Meadow Vole (shattucki), Potholes Meadow Vole (kincaid)

Taxonomy. Mus pennsylvanica [sic] Ord, 1815, “meadows below Philadelphia,” Pennsylvania, USA .

Twenty-seven subspecies recognized.

Subspecies and Distribution.

M.p.pennsylvanicusOrd,1815—extremeSEQuebecandNewBrunswick,Canada,andfromSouthDakota,N&ENebraska,andextremeNEKansasEtotheAtlanticcoastfromMaineStoSouthCarolina,USA.

M.p.acadicusBangs,1897—PrinceEdwardIandNovaScotia,Canada.

M.p.admiraltiaeHeller,1909—AdmiraltyI,Alaska,USA.

M.p.alcorniBaker,1951—fromSWAlaska,USA,EtoSYukon,Canada.

M.p.aphorodemusPreble,1902—SENunavutandNEManitoba,Canada.

M.p.axtecusJ.A.Allen,1893—restrictedrangeinNWNewMexico,USA.

M.p.chihuahuensisBradley&Cockrum,1968—knownonlyfromthevicinityofGaleana,NWChihuahua,Mexico.

M.p.copelandiYoungman,1967—extremeSNewBrunswick,Canada.

M.p.drummondiiAudubon&Bachman,1854—fromNAlaskaandNWYukonSEtoWOntario,Canada,andextremeWWashington,NIdaho,extremeNWMontana,NorthDakota,andextremeNSouthDakota,USA.

M.p.enixusBangs,1896—C&NEQuebecandLabrador,Canada.

M.p.finitusS.Anderson,1956—SWNebraska,extremeNEColorado,andextremeNWKansas,USA.

M.p.fontigenusBangs,1896—WOntarioandSQuebec,Canada.

M.p.funebrisDale,1940—SWBritishColumbia,Canada,andNEWashington,USA.

M.p.insperatusJ.A.Allen,1894—SEAlbertaandSWSaskatchewan,Canada,N&EMontana,WNorthDakota,NEWyoming,andWSouthDakota,USA.

M.p.kincaidiDalquest,1941—knownonlyfromMosesLake,CWashington,USA.

M.p.labradoriusBailey,1898—NWQuebec,Canada.

M.p.magdalenensisYoungman,1967—MagdalenIs,Quebec,Canada.

M.p.microcephalusRhoads,1894—SEBritishColumbiatoSAlberta,Canada.

M.p.modestusBaird,1858—fromCColoradoStoCNewMexico,USA.

M.p.nigransRhoads,1897—EVirginiaandNENorthCarolina,USA.

M.p.provectusBangs,1908—BlockI,RhodeIsland,USA.

M.p.pullatusS.Anderson,1956—C&EIdaho,WMontana,WWyoming,andNCUtah,USA.

M.p.rubidusDale,1940—SEAlaska,USA,andWBritishColumbia,Canada.

M.p.shattuckiHowe,1901—IsleboroandNorthHavenIs,Maine,USA.

M.p.tananaensisBaker,1951—CAlaska,USA.

M.p.terraenovaeBangs,1894—Newfoundland,Canada.

M. p. uligocola S. Anderson, 1956 — extreme SE Wyoming and NE Colorado, USA.

Descriptive notes. Head—body 107-131 mm, tail 33-64 mm, ear 12-16 mm, hindfoot 18-24 mm; weight c.44 g (both sexes). Morphology of Meadow Voles varies substantially across its large North American distribution. Pelage color varies with age and among subspecies. Dorsal fur ranges from bright yellowish chestnut to dull bister (brownish yellow), with interspersed black-tipped hairs. Northern subspecies are redder, and southern subspecies tend to be black to gray. Venter is generally gray but can tend toward white or buffy. Tail is bicolored. M, has five closed loops, M, has three transverse loops and no triangles, M* has four closed triangles and a posterior loop, and M? has three closed triangles. Chromosomal complement is 2n = 46, FN = 50.

Habitat. Mesic habitats, especially those with high grass undercover but also woodlands.

Food and Feeding. The Meadow Vole eats many species of grasses (e.g. Poa, Panicum, and Muhlenbergia, all Poaceae), sedges, mosses, other vegetation, and fungi. It occasionally eats insects and even carrion. When their numbers are high, they can affect old-field succession and damage commercial fruit trees by eating seedlings, bark, and roots. Preferred foods have low alkaloid and fiber content and high nutritive value.

Breeding. Breeding of Meadow Voles takes place in all seasons, although it only occurs in winter when populations are at high densities. Woodland populations of Meadow Voles had lower reproductive rates and lower adult survival than grassland populations. Gestation is c.21 days. Females can have up to ten litters/year. Litters have 1-11 young (average 4-6). Young are born hairless and pink. Fur begins to appear at c.4 days old, and young are covered with juvenile fur at c.7 days old. Eyes and ears open at c.8 days old. Weaning occurs at 12-14 days old.

Activity patterns. Meadow Voles are terrestrial and active day and night and throughout the year, with about a five-hour activity period/ day . Timing of activity has been related to temperature (if cold, more active during the day) and vegetative cover (if minimal, more active at night).

Movements, Home range and Social organization. Home range of Meadow Voles is 405-3580 m? for males and 160-3115 m? for females. Males tend to disperse more in winter, and females disperse more in summer.

Status and Conservation. Classified as Least Concern on The IUCN Red List. Subspecies chihuahuensis has not been recorded in recent years and is of conservation concern. Populations of Meadow Voles are known to fluctuate widely every 2-5 years, and hypotheses to explain this have been related to habitat quality, predation, secondary plant compounds, climate variability, stress due to high population densities, and other factors.

Bibliography. Ambrose (1973), Bradley, Ammerman et al. (2014), Cassola (2016j), Getz (1961b), Grant (1975), Hsu & Benirschke (1967), Keys & Van Soest (1970), Ostfeld & Canham (1993), Reich (1981), Seabloom (1965), Tamarin (1977a), Van Vleck (1969).