Peromyscus maniculatus has a small body size, no longer than that of a house mouse. It is typically 119 to 222 mm long and weighs between 10 and 24 grams. Tail length is variable in different populations and ranges from 45 mm to 105 mm (Baker 1983). Woodland forms are typically larger and have larger tails and feet than prairie forms (LTER 1995). Peromyscus maniculatus has a round and slender body. The head has a pointed nose with large, black, beady eyes. The ears are large and have little fur covering them. The vibrissae are long and prominent. Peromyscus maniculatus has shorter forelimbs than hind limbs (Baker 1983).
Peromyscus maniculatus is grayish to reddish brown with white underparts. The fur is short, soft, and dense. The finely-haired tail is bicolored, the darker top half and the lighter bottom sharply differentiated. This differs from the other species of Peromyscus (Peromyscus leucopus), in which the separation of the two colors is less distinct. There are other characteristics that help distinguish P. maniculatus from the similar P. leucopus. Peromyscus maniculatus generally has hind feet that are 22 mm or less, while P. leucopus usually has hind feet 22 mm or more. Also, Peromyscus maniculatus is more richly colored with a brownish or tawny pelage, whereas P. leucopus tends to be more pinkish-buff or grayish, with scattered dark hairs (LTER 1995). These characteristics vary geographically, however, and in some areas the two species are extremely difficult to distinguish based on external morphology.
Like most murids, Peromyscus maniculatus has a dental formula of 1/1 0/0 0/0 3/3. Its molars are low-crowned and cuspidate. The third upper molar is less wide than the first two, while that of Peromyscus leucopus is approximately as wide as the first two (Baker 1983).
Range mass: 10 to 24 g.
Range length: 119 to 222 mm.
Other Physical Features: endothermic ; heterothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: sexes alike
Average basal metabolic rate: 0.219 W.