Fulvous Harvest Mouse
Order Rodentia : Family Muridae : Reithrodontomys fulvescens J.A. Allen

Description. A small mouse with grooved upper incisors, tail much longer than head and body, and inside of ears covered with reddish hairs; differs from the pocket mice (Perognathus and Chaetodipus), which also have grooved upper incisors and long tail, in the absence of external cheek pouches. Upperparts ochraceous buff, sparingly mixed with blackish brown, sides nearly clear buff; underparts white or pale buff. External measurements average: total length, 165 mm; tail, 93 mm; hind foot, 20 mm. Weight 14-30 g, averaging about 18 g.

Distribution in Texas. Occurs in eastern two-thirds of state, including southern portion of Trans-Pecos. Absent from western Panhandle and central Edwards Plateau.

Habits. These largest of harvest mice occur chiefly in grassy or weedy areas dotted with shrubs, or in creek bottoms with their tangles of grasses, vines, and bushes. They are relatively rare in blackland prairies which are the home of the smaller plains harvest mouse, R. montanus. In favored habitat they travel from place to place on their own small trails or use those of their animal associates — cotton rats, rice rats, and white-footed mice.

In addition to living in underground burrows, many of them have penthouses in bushes above the ground. These arboreal homes may be converted birds’ nests or completely of the mouse’s own architecture. One found in central Texas was a remodeled cardinal’s nest about 1.3 m above the ground in a yaupon bush. When the nest was disturbed, the mouse quickly left it, descended to the ground by jumping from branch to branch and entered an underground burrow. The mouse’s nest, about the size of a baseball, neatly filled the cavity of the bird’s nest. It was composed of shredded grass and weed stems and had one opening on the side. Another nest was about 7 cm above the ground, in a clump of bluestem (Andropogon).

Their food is nearly all vegetable matter, including seeds and the green blades of grasses and sedges, but may include invertebrates. In coastal areas of Texas invertebrates predominate in the diet of these mice, but in regions with greater seasonal variation in climate, vegetation dominates the diet in fall and winter, while invertebrates are more important in spring and summer. Clearly, their food habits are somewhat opportunistic and based on food availability. They readily accept dry rolled oats as bait. In captivity, they eat about one-third of their own weight in food daily. They are chiefly nocturnal and are active the year round.

In Texas, it appears that the breeding season extends from February to October, although peaks in reproductive activity occur in late spring and early autumn. Litter size may range from two to five, averaging three or four. The gestation period probably is about 21 days. At birth, the young are naked, blind, and helpless and weigh about 1 g each. Weaning occurs at 13-16 days when the young weigh 3.0-3.5 g. By day 11 the young are well-furred and at 9-12 days the eyes open.

These mice seldom conflict with man’s interests. Their known predators are barn owls, barred owls, and red-tailed hawks but, doubtless, other animals also feed on them.

Photo credit: John L. Tveten.