241.

Chihuahuan Grasshopper Mouse

Onychomys arenicola

French: Onychomys des sables / German: Chihuahua-Grashlipfermaus / Spanish: Raton saltamontes de Chihuahua

Other common names: Mearns's Grasshopper Mouse

Taxonomy. Onychomys torridus arenicola Mearns, 1896, 6 mi (= 10 km) above El Paso, El Paso County, Texas, USA.

Onychomys arenicola was initially described as a subspecies of O. torridus, but it was later recognized as a distinct species based on karyotypic differences. Three subspecies were placed under O. arenicola when it was recognized as a species. Three subspecies recognized.

Subspecies and Distribution.

O. a. arenicola Mearns, 1896 — SE Arizona, SC New Mexico, and W Texas, USA (type locality — 6-0 mi above El Paso, Texas, USA).

O. a. canus Merriam, 1904 — portions of Aguascalientes, Durango, San Luis Potosi, and Zacatecus, Mexico (type locality — San Juan Capistrano, Zacatecus, Mexico).

O. a. surrufus Hollister, 1914 — portions of San Luis Potosi, and Tamaulipas, Mexico (type locality — Miquihuana, Tamaulipas, Mexico).

Descriptive notes. Head—body 85-104 mm, tail 46-55 mm, ear 16-22 mm, hindfoot 18-22 mm; weight 21-29 g. The Chihuahuan Grasshopper Mouse is similar to the other two species of Onychomys but slightly smaller in size than the Northern Grasshoper Mouse ( O. leucogaster). Dorsum is opaque brown, with intermingled darker hair resulting in grayish appearance. Venter and feet are white. Tail ranges from gray to brown and is white-tipped. Ears are brown, trimmed with white hair.

Habitat. Grassy areas and xeric scrublands with sandy or rocky soils along slopes and foothills, typically including creosote bush ( Larrea tridentata, Zygophyllaceae) and other desert or semiarid vegetation, at elevations of 1300-1580 m.

Food and Feeding. The Chihuahuan Grasshopper Mouse eats beetles and other arthropods and invertebrates.

Breeding. Chihuahuan Grasshopper Mice apparently reproduce in March-September. Females reach sexual maturity at c.8 weeks of age. Males are territorial, and they participate in care of young. Young are generally weaned 20-23 days after birth.

Activity patterns. The Chihuahuan Grasshopper Mouse is presumably nocturnal.

Movements, Home range and Social organization. The Chihuahuan Grasshopper Mouse digs shallow burrows or uses abandoned burrows of other animals. One male and multiple females live in a burrow where young are born. The Chihuahuan Grasshopper Mouse is generally rare, with densities of ¢.2-5 ind/ha.

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

Bibliography. Anderson (1972), Findley (1987), Godinez (2014), Hinesley (1979), Hollister (1914), Mearns (1896), Merriam (1904), Nowak (1991), Riddle & Honeycutt (1990).