Adults are brownish gray. Juveniles are gray. Both have dark eyes and white feet and undersides. They have four toes on the forefeet and five toes on the hind feet. Their tracks are commonly found on the fine beach sand of river bars and in soft mud.
Tracks are usually in groups of four with a trail width less than two inches.
In firm sand, sometimes a whole print will show up clearly. Mice make nests lined with the softest materials they can find. Nests are located beneath rocks and logs, in burrows, or in trees. Three or four litters of four babies each may be born per year. Mice will also gnaw on old bones and antlers to get the calcium.