140.

Mexican Vole

Microtus mexicanus

French: Campagnol du Mexique / German: Mexiko-WihImaus / Spanish: Topillo de México

Taxonomy. Arvicola (Hemiotomys) mexicanus Saussure, 1861, Volcan de Orizaba, Puebla, Mexico .

Taxonomic status and distributional limits of M. mexicanus and M. mogollonensis remain unsettled. Nine subspecies recognized.

Subspecies and Distribution.

M.m.mexicanusSaussure,1861—highplateauregionofCMexico.

M.m.fulviventerMerriam,1898—COaxaca,Mexico.

M.m.fundatusHall,1948—CMichoacan,Mexico.

M.m.madrensisGoldman,1938—SierraMadreOccidental,Chihuahua,Mexico.

M.m.neveriaeHooper,1955—SierradeManantlan,Jalisco,2500m.

M.m.ocotensisAlvarez&Hernandez-Chavez,1993—ElOcoteVolcano,WChiapas,Mexico.

M.m.phaeusMerriam,1892—fromNWDurangoStoNevadodeColima,SJalisco,Mexico.

M.m.salvusHall,1948—SierradeTancitaro,Michoacan,Mexico,atelevationsof2400-3500m.

M. m. subsimus Goldman, 1938 — isolated mountains from Sierra de Guadalupe in SE Coahuila S through Nuevo Leon to SW Tamaulipas, Mexico.

Descriptive notes. Head-body 109-127 mm, tail 24-35 mm, ear 12-15 mm, hindfoot 17-21 mm; weight 29-48 g. Dorsal pelage of the Mexican Vole is grizzled with cinnamon buff to darker cinnamon-brown hair. Sides are lighter, and venter is whitish to gray to cinnamon. Tail is relatively short and slightly bicolored, darker on top and lighter below. There are only two pairs of mammary glands unlike most other species of Microtus that have four pairs.

Habitat. Disjunct grassor forb-dominated montane meadows in pine-oak forests at elevations of 1200-4115 m. Runways of Mexican Voles are apparent in meadows, especially in vicinity of decaying logs or large boulders where they nest and rear young.

Food and Feeding. Mexican Voles eat green grasses and forbs in summer and roots, bulbs, and bark in winter. They do not cache cut vegetation, but clippings can be found along runways.

Breeding. Reproduction mainly occurs in wet summer months, but pregnant or lactating females have been found in every month in Mexico, except May and December. Gestation lasts c.3 weeks;litters usually have fewer than three young, reflecting the fact that females have only two pairs of mammary glands.

Activity patterns. Mexican Voles are terrestrial and appear to be more active during the day than most other species of Microtus; they are also active in early morning and evening.

Movements, Home range and Social organization. No information.

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

Bibliography. Alvarez & Hernandez-Chavez (1993), Alvarez-Castaneda & Reid (2016), Bradley, Ammerman et al. (2014), Brown (1960), Ceballos & Oliva (2006), Choate & Jones (1970), Crawford et al. (2011), Frey & LaRue (1993), Frey et al. (2002), Judd (1980), Modi (1987), Musser & Carleton (2005), Ramirez-Pulido, Gonzéalez-Ruiz et al. (2014), Wilson & Ruff (1999).