Pest Spotlight: Deer Mouse and White-footed Mouse

RECOGNITION & BACKGROUND

Both the deer mouse (Peromyscus maniculatus) and the white-footed mouse (P. leucopus) are small rodents having large dark eyes, large round ears, long whiskers and white undersides and feet. The hairs on the upper face, back and upper tail range in color from chestnut or reddish brown to light grayish-buff. Adult head and body length of both species range 3 to 4 inches. The tail is roughly equivalent in length to the body. Adults of both species ranges from 0.5 to 1.2 ounce.

Deer Mouse White-footed Mouse

These rodents are difficult for the novice to distinguish unless compared side by side. Identifying features include:

• The tail of the deer mouse is sharply bi-colored, dark above and white beneath; whereas the tail of the white-footed mouse does not have the dark dorsal stripe distinctly defined.
• The deer mouse’s tail is slightly longer than that of the white-footed mouse, and it has longer terminal fringe hairs.
• The white-footed mouse’s eyes are slightly more protruding and narrowly set than those of the deer mouse.

DISTRIBUTION

Deer mice occur all over North America, though sparingly in the southeastern United States. They reside in forests, prairies and even deserts. White-footed mice are in the eastern two-thirds of the continental United States, including the wooded river valleys of the Great Plains. Their range does not extend as far northward into Canada as that of deer mice. Like deer mice, white-footed mice rarely are found in the Southeastern states. Both species are native to North America and occur in rural and semi-rural (that is, newly developed) areas where they inhabit woods, fields, pastures, and tall, dense vegetation around buildings.

Like the house mouse, Mus musculus (a.k.a. M. domesticus), white-footed and deer mice are considered pests because they commonly nest in undisturbed vehicles, farm equipment, furniture, storage, structural voids and attic insulation. These mice also gnaw on electric wiring, structural materials and personal property.

However, not only do they contaminate the food supply, habitat and other situations they frequent with feces and urine, but both species present health threats:

• The deer mouse is an important mammal reservoir of the lethal pulmonary Hantavirus strain; and
• The white-footed mouse serves as one of the most significant intermediate hosts of black-legged ticks (Ixodes scapularis), which transmit Lyme disease (caused by Borrelia burgdorferi) in the Northeastern United States.

BIOLOGY

Deer mice begin to mate late in winter, producing their first litters in April. They average four litters of one to nine pups per year, depending on the abundance of food and shelter. Serial litters are produced at monthly to bimonthly intervals, spring through fall. White-footed mice exhibit similar reproduction. Typical litters number three to six pups. Both mice are generalists, feeding on foliage, stems, berries, seeds, nuts, mushrooms, insects and carrion. In and around structures, Peromyscus mice build their nests in attic soffits, fence posts, garden sheds, garages, bird houses, basement sill plates and even vehicle trunks and seats.