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  The Mammals of Texas - Online Edition

Mearns' Grasshopper Mouse
Order Rodentia : Family Muridae : Onychomys arenicola (Mearns)

Mearns' Grasshopper Mouse (Onychomys arenicola).  Photo courtesy of University Calif. Mus. Vert. Zool.Description. A small, "fat-tailed" mouse with pinkish-cinnamon or grayish-buff upperparts and pure white underparts; usually a conspicuous white or grayish tuft at anterior base of ear; nose, cheeks and sides white; tail sparsely haired, more than 30% of total length, from two to 21/2 times as long as hind foot and distinctly bicolor, dark above and white below. Similar to Onychomys leucogaster, but smaller, with relatively longer tail, and smaller teeth. Juveniles similar to adults, but upperparts bluish gray. External measurements average: total length, 146 mm; tail, 52 mm; hind foot, 21 mm. Weight of males, 26.5 (24-30) g; females, 25 (22-28) g.

Species distribution mapDistribution in Texas. Throughout the Trans-Pecos (except for the southeastern part) and a few counties east of the Pecos River.

Habits. This mouse chiefly inhabits the low, arid, sandy or gravelly desert areas where vegetation in the form of creosote bush, mesquite, yucca, lechuguilla, condalia, and so forth is sparse and scattered. It lives in burrows of its own or in those it usurps from other small rodents. Like the northern grasshopper mouse, it is relatively rare in most localities.

Its behavior and feeding habits are similar to those outlined for O. leucogaster. Breeding begins in late January or early February and continues into September. Gravid females have been captured as early as February 27 and as late as September 5. The litters vary in size from two to seven; average 4.2. Half-grown young have been captured in April, June, July, and August, suggesting that two, or even three, litters are produced each year. The young grow rapidly and females become sexually mature when 7 or 8 weeks of age. A young female can give birth to her first litter at the age of 4 months. The gestation period is 26-35 days.

Remarks. In previous editions, the scientific name for this rodent was reported as Onychomys torridus; however, recent genetic work on the species has indicated that formerly, two species have been included under that name. Consequently, the species occurring in Texas has been renamed O. arenicola, with O. torridus occupying southwestern New Mexico and westward.

Photo courtesy of University of California Museum of Vertebrate Zoology.