Peromyscus maniculatus
(Deer Mouse)

Order: Rodentia
Order Description:Rodents
Family: Cricetidae
Family Description:
Mice and Rats

The deer mouse has large ears, black, beady eyes, a distinctly bicolored tail and white feet. It occurs in two color phases, the back and sides can be gray or brown, and belly underneath is always white. Its tail is distinctly bicolored, gray or brown on top, and white underneath. Total length is 4 ¾ to 8 ¾ inches (119-22 mm), tail length is 1 ¾ to 4 ¾ inches (46-123 mm). It weighs 3/8 to 1 1/8 ounces (10-33 g).

Occurs in most of North America; absent in most of Alaska, northern Canada, and western and southeastern Mexico.

Being so widely distributed, it is found in a great variety of upland and riparian habitats, from open areas and brushlands to coniferousClick word for definition and deciduousClick word for definition forests. It is found in deserts, grasslands and woodlands. It also is attracted to human-built structures, cabins, sheds and even houses. It is commonly a pest in many rural human dwellings.

Eats arthropods, other invertebrates, fruits, nuts, seeds, green plant material, and fungi. Insects, worms, and snails are most important in summer.

Deer mice are primarily nocturnalClick word for definition, and active throughout the year. They may store food. Their home range averages 2.5 acres (1 ha) or less, but may vary from a few hundred to a few thousand square meters, depending on circumstances. They exhibit territorial behavior during high population densities. population densityClick word for definition is generally lowest in spring, highest in fall (sometimes up to about 30 per 2.5 acres (1 ha); densities as high as 109 per 2.5 acres (1 ha) and 163 per 2.5 acres (1 ha) have been reported. Idaho studies of effects of logging and grazing on small mammals show deer mice numbers were not affected by logging or grazing. Species is most abundant small mammal in most Idaho desert habitats, and most common mammal in Idaho. Being nocturnalClick word for definition, they are heavily preyed on by owls, (studies have shown that they can comprise almost half the food intake of owls), foxes and many other predators. Garter snakes seem to follow them into their nest burrows and consume the newborn mice. Considering their high reproductive potential, they obviously have a very high mortalityClick word for definition rate due to predation and other factors. They do not hibernateClick word for definition and are active under the protective cover of snow during the winter. They do construct burrows, but also utilize burrows of other small mammals, and they even construct grass-lined nests on the surface of the ground in protective cover.

Their reproductive potentialClick word for definition is extremely high, but the breeding season is shorter in their northern range and at high elevations than elsewhere. GestationClick word for definition lasts 23 days, and litter size averages 5 to 6 in their northern range, 4.5 in their southern range. Young develop rapidly; naked at birth, they grow fur and teeth in one week, and are weanedClick word for definition and become independent at about 4 weeks. Females produce 1 to 2 litters per year in the northern range, more in south. Young-of-year may attain sexual maturity by 2 months, or may not breed in some areas. Some litters are fathered by more than one male. With their high reproductive potentialClick word for definition, it is theorhetically possible for one pair of deer mice to be ancestors of about 60 mice in 20 weeks. Obviously, their mortality is high.

Status: Unprotected nongame species

Global Rank:


State Rank:


Important State References:
Groves, C.R. and B.L. Keller. 1983. Ecological characteristics of small mammals on a radioactive waste disposal area in southeastern Idaho. Amer. Midl. Natur. 109:253-265.

Information written by Donald Streubel,© 2000
Map image provided by
Stephen Burton,© 2000
Design by Ean Harker©1999, 2000.