Forest Preserve District of Cook County, Illinois
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Deer Mice and White-Footed Mice
Nature Bulletin No. 545-A   November 23. 1974
Forest Preserve District of Cook County
George W. Dunne, President
Roland F. Eisenbeis, Supt. of Conservation

At night, sitting on a wooded shore, waiting for fish to bite or quietly gazing into the coals of a camp fire, you often become aware of mysterious small noises nearby in the darkness. Sometimes it is only a faint scratching on a tree trunk, or a rustling in the fallen leaves. But, again, you may hear a tiny drumming sound or a musical buzzing hum. Spooks? No.

The best guess is that you have disturbed the night life of a wild mouse. He makes the drumming sound by rapidly tapping a dry leaf or hollow stem with his front feet. Unlike house mice, his voice is more of a song than a mere squeak. If you catch him in the beam of a flashlight you see an alert animal face with big ears, large black bulging eyes, and a beautiful coat -- rich brown above with snow-white underparts and feet. From these prominent characteristics came the common names of our two local species, the Deer Mouse and the White-footed Mouse.

Outside of cities, from the Arctic Circle to Panama, there is hardly an acre without one of these mice or one of their nearly related species and varieties. While they go largely unnoticed because of their nocturnal habits, they may be America's most numerous mammals. Although quite similar in appearance, our native deer mouse is slightly smaller than a house mouse and the white-footed mouse is a trifle larger. Adults weigh about an ounce each. In many ways they are more like little squirrels than mice.

The deer mouse is an inhabitant of prairies, weedy fields, fencerows and roadsides. Its nests are often found under rocks, boards, haystacks and corn shocks. The nest, about the size of two cupped hands, is made of coarse outer materials with a soft inner lining of plant fibers, fur or feathers.

In contrast, the white-footed mouse is a dweller of forests, brushlands and wooded river bottoms. It is a good climber and uses its long tail to balance it when running along twigs in search of food. Its nest may be in a fallen log or under a stump but, more often, it is in a woodpecker hole, a bird house, or an abandoned bird nest over which it builds a roof. They seldom come into our houses but often invade empty summer cottages where they make themselves snug homes in chair cushions, mattresses and stored clothing.

The food of these two mice is mostly seeds of grasses, weeds and berries which they carry in their cheek pouches and often store by the quart. Eating in bed is customary. They do not hibernate. After every fresh snow their tiny tracks show where they have been foraging the night before. To this diet they add buds, insects, spiders, centipedes and land snails. Small rodents such as these need more food in proportion to their weight than do larger warm-blooded animals. A one-ounce mouse eating a half-ounce of food per day is no better fed than a 1000-pound horse eating 20 pounds a day.

Deer mice and white-footed mice are prolific. The females begin to breed at two months of age and bear litters of about 4 or 5 young each month throughout a large part of the year. The pink wrinkled naked young are born with their eyes and ears closed. The eyes open after two weeks and at three weeks, when half-grown, they are weaned. Then their mother moves out and builds a new nest. Two years is a ripe old age because almost every night-hunting owl and meat-eating mammal preys on them.

They won't eat cheese and they don't smell mousy.

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