The deer mouse is a moderately small mouse-like rodent that exhibits considerable variation in color, tail length and markings. In general, the pelage of adult deer mice is buff to dark brown on the dorsum and white on the venter. The ears are moderately long, essentially naked and usually held erect and directed forward. The eyes are black and beady.
The deer mouse has the broadest distribution of any species within the genus and occurs throughout Oregon. Below the treeline, it occurs as part of essentially all communities.
It is active nocturnally, the time of onset of activity is cued by light and is remarkably precise, but does not seem to be influenced by clouds. It nests in trees, burrows in the ground, crevices in rocks, and a variety of other places. Communal nesting is observed frequently.