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  The Mammals of Texas - Online Edition

Rock Pocket Mouse
Order Rodentia : Family Heteromyidae : Chaetodipus intermedius Merriam

Description. A medium-sized, long-tailed pocket mouse; pelage rather harsh, with weak spines on rump; sole of hind foot naked to heel; tail longer than head and body, crested and distinctly tufted; upperparts drab, with strong admixture of black on back and rump; lateral line pale fawn, narrow; tail dusky above, white below; underparts white. Similar externally to C. penicillatus, but hind foot usually smaller, upperparts much darker, tail with smaller scales and narrower annulations. External measurements average: total length, 180 mm; tail, 103 mm; hind foot, 23 mm. Weight, 12-18 g. Dental formula as in Perognathus flavescens.

Species distribution mapDistribution in Texas. Reported only from the Trans-Pecos region.

Habits. This species inhabits chiefly rocky situations, often where boulders are large and jumbled. At the eastern base of the Guadalupe Mountains in western Texas they have been found inhabiting rocky canyons, and in the Wylie Mountains they lived among huge boulders. Occasionally, they may be found on shrubby desert slopes on pebbly soils, rarely on silt soils. Vernon Bailey reported finding them on sandy soils among rocks. It is our impression that they rarely occur in areas of loose, alluvial, and windborne sands.

Their burrows are small, inconspicuous, and often closed during the daytime. Tiny trails lead away from them to feeding places among the plants. They choose burrow sites close to or under rocks.

They are strictly nocturnal and little is known of their habits. Their food is chiefly weed seeds, the species of plants utilized depending on availability. Judging from the meager data, breeding begins in February or March and continues for several months. Gravid females have been captured in May, June, and July. The litter varies from three to six. Nearly halfgrown young in juvenile pelage have been taken in April, May, June, and August. Their general habitat is such that they seldom conflict with man’s interests.