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  The Mammals of Texas - Online Edition

Deer Mouse
Order Rodentia : Family Muridae : Peromyscus maniculatus (Wagner)

Deer Mouse (Peromyscus maniculatus).  Photo by R.M. Bond.Description. A small, white-footed mouse with sharply bicolor tail, white beneath and dark above; ears usually shorter than hind foot, prominent and leaflike; upperparts bright fulvous or brownish, intermixed with dusky; underparts and feet white. External measurements average: total length, 170 mm; tail, 81 mm; hind foot, 20 mm; ear, 18 (12-20) mm. Weight, 15-32 g.

This species is most easily confused with Peromyscus leucopus, from which it differs in (1) sharply bicolor tail, (2) more hairy and often shorter tail, (3) frequently whitish tufts of hair at base of ears, and (4) usually longer pelage.

Species distribution mapDistribution in Texas. Statewide but uncommon in the eastern, coastal, and southern parts of the state.

Habits. These mice occupy a variety of habitats, ranging from mixed forests to grasslands to open, sparsely vegetated deserts. In Texas, they usually inhabit grasslands or areas of open brush, especially where weeds and grasses offer concealment and a source of food. Weed-choked fence rows and washes offer almost ideal habitat. Mice of this group seem to be poor climbers and live close to or on the ground.

They are almost strictly nocturnal. Trapping records indicate that they leave their daytime retreats early in the evening and remain abroad until shortly after sun up. They live in underground burrows, in brush piles, or in crevices among rocks. The burrow is simple in design and usually consists of two or three short branches converging from as many surface openings to a single tunnel that slopes steeply to the globular nest chamber which is 7-10 cm in diameter. The nests are hollow balls of dry grass, shredded weed stems, and other available material including rabbit fur and bird feathers.

Deer mice do not hibernate. Their winter activities may include taking up quarters in a pile of logs, from which they venture nightly in search of food. The tracks of one mouse led from the logs to one bush after another in a wandering fashion to the edge of a bare field some 100 m distant and then back to the log pile. The others traveled less than 50 m from their headquarters. Bits of bark, leaves, and seed coats scattered on the snow beneath many of the bushes indicated that they had climbed into them in quest of food. Their food consists of a variety of items, chiefly seeds. In season fruits, bark, roots, and herbage are also consumed and, judging from the behavior of these mice about camps, nearly everything edible is sampled.

Deer mice breed in every month of the year, with peaks in the periods from January through April and from June through November. Litters seem to be born in rapid succession — one captive female produced 11 litters with 42 young in a year. The gestation period varies from 22 to 27 days, averaging about 24 days. Litter size ranges from one to nine, averaging about four. At birth the young are blind, pink, and hairless and weigh from 1.1 to 2.3 g. They become pigmented dorsally in about 24 hours, the pinna of the ear unfolds on the third day, the eyes open in 12-17 days, and they are weaned when about 4 weeks old. The longest observed time of suckling is 37 days. Sexual maturity is reached before the young lose their "blue" juvenile pelage, and females born early in the year may themselves produce young by late summer or early fall.

These mice are often abundant in favorable habitats and then, as with other animals that overpopulate an area, they may become troublesome. Because of their tolerance to a wide variety of habitat conditions and their often large population they are difficult and expensive to control. Since they are an important source of food for many small carnivores, owls, and snakes, the assistance of these animals should be enlisted in keeping the populations of mice within bounds.

Photo credit: R. M. Bond.