A species of white-footed mice, the deer mouse (Peromyscus maniculatus) is the most common kind of New World mice, including around 65 subspecies. Their bodies range in size from 4.75-8.5 in (12-22 cm), and their tails measure between 3.25-7 in (8-18 cm). Deer mice are probably the most abundant mammal in the western United States. These mice eat both plants and insects and are most active at night.
They are noted for their practice of gathering large quantities of food and hiding it in numerous locations to see them through times of bad weather. Since they do not hibernate, this practice is essential to their survival. Deer mice are quite fertile; they are able to bear young at seven weeks old and have litters of up to nine young after a pregnancy lasting three or four weeks.