Deer mice are the prototype for "field mice" with large, bulging eyes, big ears, a bicolored pattern and a long tail. They are larger than the harvest mice, but noticeably smaller than woodrats and cotton rats. The deer mouse is about 148-200 mm (seven in.) long, including the tail. The bicolored tail is less than 90% of the head and body length; this distinguishes the deer mouse from the high desert piñon mouse, which has a tail over 90% of the head and body length.

The deer mouse coloration is described as "bicolored", meaning it has a distinctly darker upper body coloration compared to the white undersides. The body color varies from a yellowish or reddish brown to grayish above, with pure white undersides and feet. The bicolored body and distinctive large ears distinguish the deer mouse from the introduced house mouse, which is uniformly gray. The house mouse is found in city and urban areas while the deer mouse prefers natural habitats. You can get either where development pushes against undeveloped lands.

Life Cycle:

Females breed each month, producing up to 42 young every year. Female offspring born in early spring can begin reproducing by late summer. A male, several females, and young make up the basic social structure of a colony. Winter months they huddle together in groups of 10 or more in nests to stay warm. They live up to 8-years.