Deer mice feed on a variety of organic matter from seeds, nuts, fungi and fruit to insects and small invertebrates. They even feed on their own feces during times of food scarcity.
Deer mice tend to stockpile food during the fall, storing the items in larder nests. These larder nests are connected to their living nests and act as storerooms during the winter. Deer mice are also a food source for other predators such as foxes, weasels, coyotes, snakes and owls. Due to these predators, deer mice in the wild have short life spans of about one year.
Predation helps to control deer mice populations. A single female door mouse can give birth to nearly 100 young every year. The young then start reproducing at five weeks old.
Deer mice help to disperse seeds throughout the environment and act as a food source for predators, but large and uncontrolled populations can have many negative effects. Deer mice can ravage forests and crops and raid grain supplies. They can also carry diseases dangerous to humans such as Lyme disease and hantavirus. Once the hantavirus infects humans, the fatal hantavirus pulmonary syndrome can develop.
Deer mice grow between 5 and 9 inches long, although several of those inches belong to the tail alone. These small rodents usually thrive in the woodlands of North America.