236.

Western Harvest Mouse

Reithrodontomys megalotis

French: Souris-moissonneuse de |'Ouest / German: Westliche Erntemaus / Spanish: Raton espiguero occidental

Other common names: Southern Marsh Harvest Mouse

Taxonomy. Reithrodon megalotis Baird, 1858, “between Janos, Sonora [Mexico] and San Luis Springs [New Mexico, USA].”

Reithrodontomys megalotis is in subgenus Reithrodontomys . Fifteen subspecies recognized.

Subspecies and Distribution.

R.m.megalotisBaird,1858—fromextremeSCBritishColumbia(Canada)SthroughtheWthirdoftheUSAtoMichoacanState(CMexico).

R.m.alticolusMerriam,1901—EGuerreroandOaxacastates(SCMexico).

R.m.amolesA.H.Howell,1914—knownonlyfromthetypelocalityandsurroundingareainSierraGorda,QuerétaroState,CMexico,atanelevationofabout2285m.

R.m.arizonensis].A.Allen,1895—knownonlyfromthetypelocalityinChiricahuaMts,SEArizona,USA,atanelevationofabout2440m.

R.m.aztecus|].A.Allen,1893—SEUtah,SColorado,SWKansas,NEArizona,N&CNewMexico,NWTexas,andOklahomaPanhandle(USA).

R.m.catalinaeElliot,1904—SantaBarbaraI,California(USA).

R.m.distichlisvonBloeker,1937—smallregionofWCCalifornia(USA).

R.m.dycheiJ.A.Allen,1895—fromSEAlbertaandSWSaskatchewan(Canada)EtoSWWisconsin,WCIndiana,andMissouri,andStoNEColorado,Kansas,andNEArkansas(USA).

R.m.hooperiGoodwin,1954—knownonlyfromthetypelocalityandsurroundingareainWCTamaulipasState(NEMexico).

R.m.limicolavonBloeker,1932—knownonlyfromthetypelocalityandsurroundingareainSWCalifornia(USA).

R.m.longicaudusBaird,1858—SWWashingtonandWCalifornia(USA)andNWBajaCaliforniaState(NWMexico).

R.m.peninsulaeElliot,1903—NBajaCaliforniaState(NWMexico).

R.m.ravusGoldman,1939—knownonlyfromthetypelocalityandsurroundingareainNUtah(USA).

R.m.santacruzaePearson,1951—SantaCruzI,California(USA).

R. m. saturatusJ. A. Allen & F. M. Chapman, 1897 — from Coahuila and Nuevo Leon S to México, Morelos, Puebla, and Veracruz states (Mexico).

Descriptive notes. Head-body 63-74 mm, tail 55-96 mm, ear 10-16 mm, hindfoot 14-20 mm; weight 8-13 g. The Western Harvest Mouse is small. Dorsum is light brown or grayish to blackish at base, with buffy tips. Venter is dark buff to white, often with buffy pectoral spot. Tail is bicolored and equal to head-body length.

Habitat. Widespread in various habitats ranging from pine-oak forests to natural grasslands at elevations 76 m below sea level in Death Valley, California (USA) to 4000 m. In forested areas, Western Harvest Mice are typically found in areas covered with grass, weeds, and shrubs.

Food and Feeding. The Western Harvest Mouse is mainly granivorous but occasionally eats plant material and invertebrates.

Breeding. Males tend to be polygamous. Offspring are born in spherical nests ¢.12 cm in diameter, constructed with grass and other vegetation. Gestation is c.5 days. Litters have 1-9 young. Young are altricial birth and are weaned after c.25 days.

Activity patterns. The Western Harvest Mouse is nocturnal and mainly terrestrial.

Movements, Home range and Social organization. Home ranges are large at ¢.3500 m?. Generally, densities are 4-11 ind/ha but in exceptionally good years can increase to 60 ind/ha. In central Mexico, densities of 0-7-15-8 ind/ha have been reported in open areas and fields.

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

Bibliography. Allen (1893, 1895a), Allen & Chapman (1897a), Baird (1858), Bell et al. (2001), von Bloeker (1932, 1937), Ceballos & Galindo (1984), Elliot (1903b, 1904a), Fa et al. (1990), Fisler (1965), Goldman (1939), Goodwin (1954), Gray (1943), Hall (1981), Hood et al. (1984), Hooper (1952a), Howell (1914), Long (1962), Merriam (1901b), Meserve (1976), Pearson (1951b), Sanchez (1993), Sanchez & Oliva (2014c), Webster & Jones (1982), Whitford (1976).