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

****:DEER MICE AND WHITE-FOOTED MICE

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.