328.

West Mexican Cotton Rat

Sigmodon mascotensis

French: Sigmodon du Jalisco / German: \Westmexiko-Baumwollratte / Spanish: Rata de algodén de México occidental

Other common names: Jaliscan Cotton Rat

Taxonomy. Sigmodon mascotensis |. A. Allen, 1897, Mascota, Mineral San Sebastian, 1006 m, Jalisco, Mexico.

Sigmodon mascotensis was thoughtto include three diagnosably different populations treated as valid subspecies, but recent revision emphasized that broad patterns of intraspecific variation did not accord with conventional subspecific designations. Until a thorough review is conducted,it is premature to diagnose subspecies or map geographic and ecological distributions. Monotypic.

Distribution. Coastal plain and interior basins of W Mexico, from S Nayarit, extreme S Durango, and SW Zacatecas S to extreme SW Chiapas, and E into W Hidalgo, W Puebla, and NW Oaxaca .

Descriptive notes. Head-body 125-200 mm, tail 75-138 mm, ear 17-23 mm, hindfoot 30-40 mm; weight 70-211 g. The West Mexican Cotton Rat is large-bodied; dorsal pelage is distinctly colored, a mix of black long and thin hairs and brown thick and short hairs, with shades varying from yellowish to reddish; fur is paler on sides and cheeks; and belly is grayish white, with bases of hairs dark gray and tips white. Tail is shorter than head-body length, sparsely haired and thus noticeably scaly, and bicolored, dark on top and light beneath. Forefeet and hindfeet are yellowish white above. Chromosomal complementis 2n = 28 but polymorphic in some populations with 2n = 27-28, FNa = 28.

Habitat. Brush stands, mixed savanna-scrublands, and around agricultural fields bordered with rank brush in arid tropical deciduous forest and oak ( Quercus, Fagaceae) and pine-oak woodland from sea level to elevations of ¢.2500 m (most collecting locations 500-1500 m). The West Mexican Cotton Rat is commonly captured in tall grasses interspersed among rocks, bare soil, and scattered oaks and cactus. In tropical deciduous forest in Colima, Mexico, preference was for open canopy, dense and low vegetation with little ground litter, and longer distances to the nearest tree.

Food and Feeding. The West Mexican Cotton Rat eats primarily seeds but also vegetation such as stems and roots, insects, and other animals.

Breeding. Reproduction occurs year-round, with pregnant females found in March, May, July, and December, and juveniles in February and July. Gestation is 27 days, and litters have 1-12 young (average five). Offspring are very precocial.

Activity patterns. The West Mexican Cotton Ratis terrestrial and can be active day and night.

Movements, Home range and Social organization. The West Mexican Cotton Rat uses well-defined runways to move through dense vegetation, and reaches local densities of 0-84-25-3 ind/ha. Burrows are built primarily in dense vegetation and at bases of stumps and root masses. At Chamela, Jalisco, average distance traveled by two males in a single night was 18-1 m.

Status and Conservation. Classified as Least Concern on The IUCN Red List. The West Mexican Cotton Rat has a wide distribution and presumably large overall population, occurs in several protected areas, tolerates significant disturbance, and lacks of known conservation threats.

Bibliography. Allen (1897b), Alvarez-Castaneda, Castro-Arellano, Lacher, Vazquez & Arroyo-Cabrales (2016), Bailey (1902), Carleton et al. (1999), Ceballos (2014a), Elliot (1903a), Goodwin (1956), Hall (1949), Matson & Baker (1986), Ramirez & Chavez (2014d), Russell (1952b), Schnell, Romero-Almaraz et al. (2010), Swier et al. (2009), Zimmerman (1970).