Deadly Deer Mice

Cabin Fever

Despite their clean white feet and handsome appearance, Ponderosa pine Forest-loving DEER MICE SHOULD BE PUT OUTDOORS suspect that most people get acquainted with Peromyscus maniculatus, less formally known as the "deer mouse," only when they happen to share a rustic forest cabin with one or more of these lively little rodents. In fact, deer mice can be a little too lively for the average city dweller who thinks a vacation cabin should shelter one mammal species (human beings) and no more. For some people, however, having a deer mouse or two make an evening dash around the living room proves mildly entertaining, especially if the cabin lacks other amusements such as television. These mice move so rapidly when they sense they are being watched that it may be hard to detect the characteristics that distinguish Peromyscus maniculatus from the seven other closely related species of Arizona's deer mice. For example, the deer mouse and the white-footed mouse (Peromyscus leucopus) seem almost identical, although the whitefooted mouse is somewhat larger (8 inches long, nose to tail tip, rather than 7) and has a more prominently bicolored tail. Even without a clear read on tail color, you easily can tell the difference between deer mice and another secretive guest, the house mouse (Mus musculus). Deer mice, with their white bellies and clean white feet, are more sleek and handsome than the dark gray house mouse, which is far more dependent upon humans and our buildings. Admittedly, when a deer mouse decides to take a page from the house mouse handbook, it resourcefully makes itself at home around people. We once opened a kitchen drawer in a rental cabin to find a large mouse nest composed of paper strips and insulation, complete with six tiny baby deer mice. The helpless pinkies normally would have been closely attended by their mother, but she sensibly departed, temporarily, when we opened the drawer. After a bit, we closed the drawer, permitting the mother mouse to return to her brood.

Deeply devoted to their babies, deer mice moms huddle over them to keep them warm and let them nurse regularly. With no interest in family life, deer mice males have already moved on, being far more interested in inseminating as many females as possible. Baby deer mice respond to maternal care by growing rapidly into independent adults in a little less than a month. When they're 6 weeks old, the females from the brood we spared would have been getting pregnant, and by 10 weeks, they might have had their own bundles of pinkies elsewhere in the cabin. They have to move fast because deer mice rarely live for more than a year in the wild.

Although we didn't evict the deer mouse clan and were none the worse for the wear, I now know that this pretty little mouse does pose a health risk. Like some other rodents, the deer mouse occasionally carries a type of hantavirus, which can infect humans if they happen to inhale microscopic airborne particles of mouse urine, feces or nesting material. So when cleaning up after mice, don't use a broom, which can stir up dust; instead, don rubber gloves and a dust mask and disinfect the area with a diluted bleach solution.

Doctors identified the deer-mouse hantavirus as a people-killer in 1993, after a series of deaths associated with an unusual respiratory illness in northeastern Arizona and surrounding areas. Subsequently, hantavirus pulmonary syndrome has been documented in more than 30 states where deer mice roam.

Given the infection's often lethal nature, it's unwise to live closelywith deer mice. Although killing these lovely little creatures is not pleasant, perhaps you can take comfort in knowing that Peromyscus maniculatus does very well outdoors, where it offers a health threat to no one.

Indeed, the deer mouse rates as one of the most common North American mammals, living across all of the United States except in the southeastern corner of our nation. The mouse scampers through Arizona ponderosa pine forests, California beach dunes and Massachusetts deciduous woodlands. Its abundance and wide distribution partly come from its ability to eat the seeds of many plants while also polishing off caterpillars and other insects, to say nothing of that piece of apple pie left on the cabin's kitchen counter. So finish the pie the next time you rent a cabin in the woods, since you don't need to feed any unadvertised population of deer mice. Admire these good-looking, energetic mice at a healthful distance. AH