Silky Pocket Mouse
Order Rodentia : Family Heteromyidae : Perognathus flavus Baird

Description. A small pocket mouse with soft, silky fur, short ears, and short, sparsely haired tail; upperparts pinkish buff, lightly mixed with black; underparts pure white; spot behind ear clear buff and conspicuous; ears light buff on outside, blackish inside; tail pale buffy, slightly darker above. Closely resembles Perognathus merriami, from which it differs in minor features of the skull and the frequency of biochemical genetic markers. External measurements average: total length, 113 mm; tail, 50 mm; hind foot, 16 mm. Weight, 6-8 g. Dental formula as in Perognathus flavescens.

Distribution in Texas. Known from the Trans-Pecos and extreme northern Panhandle.

Habits. Silky pocket mice appear to be more tolerant of habitat conditions than some of the other species of small pocket mice. In some areas they are found in rocky situations; in others on hard, stony soils; and in still others on sands. In most localities, however, they occur on mellow soils of valley bottoms where they live among the scattered weeds and shrubs and burrow in the sand.

As with other species of pocket mice the burrows of flavus are simple in design, usually shallow and barely large enough to admit a man’s finger. One excavated near Sierra Blanca, Texas was in the bank of a dike thrown up to divert water from the highway. The three openings converged to a single burrow that led along the dike for a distance of about 1 m, at no place penetrating more than 10 cm below the surface. Two side branches diverged from the main burrow, one of them sloping upward to near the surface. This branch probably was a "duck-out," because the occupant escaped from it by breaking through the thin crust of earth at the blind end of the tunnel. No nest or store of food was encountered, although this mouse is known to store food in captivity.

The diet consists wholly of seeds, so far as known. Juniper berries and seeds of grasses and weeds provide the bulk of their diet.

The breeding season extends from early spring to late fall. Half-grown young have been captured as early as April 16 and as late as September 23, and a lactating female was captured in December. Probably two or more litters of two to six young are reared each season. Nothing is known of the growth and development of the young and the family relations. An adult female lived in captivity for more than 5 years, but the age attained in the wild is probably not more than 2 or 3 years.

Photo credit: John L. Tveten.