303.

Saxicoline Deermouse

Peromyscus gratus

French: Péromyscus gracieux / German: Felsliebende Hirschmaus / Spanish: Raton ciervo de roca

Other common names: Osgood’'s Mouse

Taxonomy. Peromyscus gratus Merriam, 1898, Tlalpan, Distrito Federal, Mexico.

Peromyscus gratus is in the truer species group. It was considered a subspecies of P truer; however, chromosomal and DNA sequence data were used to elevate it to a distinct species, with the name P. true: being applied to populations from northern Texas, USA, to Baja California, and P. gratus to populations from south-western New Mexico, USA, to Oaxaca, Mexico. Some authorities recognize erasmus as ajunior synonym of gentilis. Four subspecies recognized.

Subspecies and Distribution.

P.g.gratusMerriam,1898—fromCJaliscoandextremeSESanLuisPotosiE&StoTlaxcala,Mexico.

P.g.erasmusFinley,1952—knownonlyfromthetypelocalityinCDurango,Mexico.

P.g.gentilisOsgood,1904—SWNewMexico,USA,andfromNWChihuahuaStoNJaliscoandNGuanajuato,Mexico.

P. g. zapotecae Hooper, 1957 — from S Tlaxcala S to NC Oaxaca, Mexico.

Descriptive notes. Head-body 95-108 mm,tail 76-123 mm, ear 18-25 mm, hindfoot 20-27 mm; weight 20-33 g. The Saxicoline Deermouse is medium-sized, with dorsal pelage that generally includes yellowish gray or ocherous mixed with gray. Sides have buffy to ocherous lateral line. Venter and feet are whitish. Tail is bicolored, brownish or dusky above and whitish below. Ears are large, generally larger than hindfeet. Auditory bullae are large and inflated.

Habitat. Woody or brushy habitats, pine-oak forests, lava fields, grasslands, and fields at elevations of 1710-2700 m. Saxicoline Deermice can be found in rocky areas and canyons.

Food and Feeding. Diet of the Saxicoline Deermouse consists primarily of green plant material, seeds, and fungi, although insects and other invertebrates are occasionally eaten. In several areas,fruits ofJuniperussp. ( Cupressaceae) seem to be a favorite food item.

Breeding. Reproduction of the Saxicoline Deermouse occurs in May—December but more often in the rainy season (July-October). Gestation lasts 25-27 days, and average litter size is three offspring. Young are weaned at 21-28 days old and are sexually mature after 50 days.

Activity patterns. The Saxicoline Deermouse is presumably nocturnal. It is thought to be semi-arboreal and frequently constructs burrows in rock crevices or under fallen logs and trees.

Movements, Home range and Social organization. Average density of Saxicoline Deermice is 33-7 ind/ha.

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

Bibliography. Anderson (1972), Baker & Greer (1962), Ceballos & Galindo (1984), Chavez, J.C. (1993, 2014a), Chavez, J.C. & Ceballos (1994), DeWalt et al. (1993), Durish et al. (2004), Goodwin (1969), Hernandez-Chavez (1990), Janecek (1990), Lee et al. (1972), Modi & Lee (1984), Musser & Carleton (2005), Servin et al. (1994), Zimmerman etal. (1978).