Plains Harvest Mouse
Order Rodentia : Family Muridae : Reithrodontomys montanus (Baird)

Description. A small harvest mouse about the size of R. humulis and considerably smaller than R. megalotis and R. fulvescens; tail usually less than half of total length and distinctly bicolor, dark above and light below; upperparts mixed brown and pale yellowish gray; outside of ears and flanks pale yellowish brown; underparts dull whitish. External measurements average: total length, 116 mm; tail, 54 mm; hind foot, 15 mm. Weight, 6-10 g.

Distribution in Texas. Found in western and central parts of state, east and southeast to Madison and Bexar counties, respectively.

Habits. These mice appear to prefer climax, or nearly climax, well-drained grassland. In Brazos County they occur most commonly in blackland prairies where the dominant vegetation is bluestem grass (Andropogon). Their nests are composed of fine grass compacted into small balls and are either in bunch grass or just beneath the ground in their burrows.

Their food consists of green parts and seeds of a variety of plants, including small grains. In captivity they readily accept rolled oats and sunflower seeds.

Available data indicate a year-long breeding period, at least in Texas. A female captured January 13 near Bryan gave birth to four young in the trap; a gravid female was trapped in October. A captive gave birth to litters in September, October, March, and April. The gestation period is approximately 21 days; the number of young per litter ranges from two to five, averaging three. At birth the young are blind, naked, and weigh about 1 g. They are well-haired in 6 days, their eyes open in 8 days, and they are weaned in about 14 days. They are as large as adults in 5 weeks and sexually mature in about 2 months.

Photo credit: John L. Tveten.