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Deer Mouse

The deer mouse (Peromyscus maniculatus) is a small, native rodent with an almost ubiquitous distribution in North America. The deer mouse ranges from the subarctic boreal forest, through wide areas of more southern conifer and mixed-wood forests, to drier habitats as far south as some regions of Mexico.

The deer mouse is highly variable in size and color over its range. Its body length ranges from 2.8 to 3.9 in (7 to 10 cm), the tail 2.0-5.1 in (5-13 cm), and the body weight 0.6-1.2 oz (18-35 g). Many geographic variants of the deer mouse have been described as subspecies. The color of the deer mouse ranges from greyish to reddish brown, with the body being dark above and white beneath. The bicolored coat of these mice gives rise to its common name, a reference to a superficial resemblance to the coloration of white-tailed and mule deer (Odocoileus spp.). The deer mouse can be difficult to distinguish from some closely related species, such as the white-footed mouse (P. leucopus), another widely distributed, but more eastern species.

The deer mouse occurs in a very wide range of habitat types. This species occurs in deserts, prairies, and forests, but not in wetlands. The deer mouse is quite tolerant of certain types of disturbance, and its populations are little affected by light wildfires or the harvesting of trees from its habitat.

The deer mouse nests in burrows dug in the ground, or in stumps or rotting logs. This species also sometimes nests in buildings. Deer mice can climb well, and they do so regularly in certain habitats. The deer mouse is a nocturnal feeder on a wide range of nuts and seeds, and when this sort of food is abundant it is stored for leaner times, because deer mice are active all winter. Deer mice also feed on insects when they are available.

The home range of deer mice can vary from about 0.5 to 3 acres (0.2 to 1.2 hectares), but this varies with habitat quality and also over time, because the abundance of these rodents can be somewhat irruptive if food supply is unusually large. Within any year, deer mice are generally most abundant in the late autumn, and least so in the springtime. Deer mice are quite tolerant of each other, and during winter they may sleep huddled in a cozy group to conserve heat. The typical longevity of a wild animal is two years, but deer mice can live for eight years in captivity.

Depending on latitude, the deer mouse breeds from February to November, raising as many as four litters per year of typically three to five young each. Young deer mice are capable of breeding once they are older than five or six weeks. Adult males often assist with rearing their progeny.

When they are abundant, deer mice are important prey for a wide range of small predators, such as foxes, weasels, hawks, owls, snakes, and other species. In this sense, deer mice and other small mammals are critical links in ecological food webs.

Deer mice are sometimes a problem in forestry, in situations where they eat large quantities of tree seeds and thereby inhibit the natural regeneration of harvested stands. However, deer mice also provide a service to forestry, by eating large numbers of potentially injurious insects, such as sawflies and budworms.

Deer mice may also be considered pests when they occur in homes, because they raid stored food and may shred fabrics and furnishings to get material with which to build their nests. In some regions, exposure to the feces of deer mice may result in people developing a potentially deadly disease caused by a microorganism known as hantavirus.

However, when closely viewed, deer mice prove to be inquisitive and interesting creatures. Deer mice are readily tamed, and they make lively pets.

Bill Freedman

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