(Reithrodontomys humulis humulis)
This species is small with a total length of 117-152 mm. The tail is about half of the total length. The upper parts are dark cinnamon, darkest on the back, and brightest on the shoulders and flanks. It can be distinguished from Reithrodontomys humulis virginianus by a reddish rather than grayish coloration. It is easily distinguished from most other mice by the small size. The breeding season is generally from late spring to late fall, although some breeding activity may occur in the winter. The litter sizes range from 1 to 8 with an average of 3.4. Territoriality is lacking. The home range size varies throughout the year, being greater in size during the summer than in the winter. The mice are essentially nocturnal, but during periods of cold weather may gather food during the day. The nest is generally a small globular clump of shredded leaves and plant fibers, and is usually placed on the ground or sometimes several inches above the ground in a clump of grass. This species can exist for long periods without water. Longevity is at least 10 months.
They inhabit The Dismal Swamp and all of western Virginia west of the central Piedmont. This species is mainly found in certain habitats dominated by grasses and other herbaceous plants characteristic of early vegetational succession on old fields. It is also taken in wet, marshy areas.
The food habits are poorly known. It is known to eat primarily seeds and sometimes leaves of grasses and herbs. They will also eat insects.