Eastern Harvest Mouse
Order Rodentia : Family Muridae : Reithrodontomys humulis (Audubon and Bachman)

Description. A diminutive harvest mouse like R. montanus, but upperparts deep brown or gray, heavily mixed with black, especially on the mid-dorsal area; ears blackish all over rather than dark at the base and light at the tip; tail about as long as head and body, the dark dorsal and light ventral stripes about equal in width. External measurements average: total length, 126 mm; tail, 61 mm; hind foot, 16 mm. Weight, 10-15 g.

Distribution in Texas. Known in the eastern part of the state, west to Fort Bend, McLennan, and Hunt counties.

Habits. The eastern harvest mouse is found mainly in habitats dominated by grasses and other herbaceous plants characteristic of early vegetational succession, including places such as abandoned fields, weed-filled ditches, and briar thickets.

Eastern harvest mice are essentially nocturnal, although at times they may be active during the daylight hours, particularly during cold weather. During periods of cold weather, these mice huddle together in the nest at night to reduce heat loss from their bodies, and they feed in the daytime when it is warmer.

R. humulis constructs nests of shredded grass and plant fibers that are placed on the ground in tangled herbage or above the ground in a clump of grass. The nest, which is about the size of a baseball, generally has a single entrance.

Although breeding may occur throughout the year, most births take place between late spring and late fall. Litter sizes range from one to eight (average, three to four), and the gestation period is 21-22 days. At birth the young weigh approximately 1.2 g. The eyes do not open until 7-10 days, and weaning takes place between the second and fourth weeks. The young become sexually mature and are capable of breeding at about 11-12 weeks of age.

The food habits of R. humulis are not well known. They appear to feed almost wholly on seeds and grain, but are known to eat grasshoppers and crickets while in captivity.

Photo credit: John L. Tveten.