The Fulvous Harvest Mouse is a typical field mouse. It does not hibernate and is active chiefly at night, but occasionally during the day as well. It is an agile climber, and will scale plants and grasses to feed on seeds or berries. This mouse builds small compact nests which are frequently placed in shrubs, vines, clumps of grasses, bird nests, holes in trees or underground, and which are used throughout the year. The nest is woven from dry grasses and plant stems, and has a small opening on one side of the nest. In winter these nests usually are underground. This mouse does not need established trails, but will use trails made by other small mammals.
The Fulvous Harvest Mouse essentially is a vegetarian, eating seeds, tender sections of grasses and fruits, but occasionally it will eat insects.
Because of its limited distribution in Kansas, little is known about the reproduction of this mouse. Elsewhere it has a litter size of two to five young which are born hairless and blind after a gestation period of 21 days. The young are nursed from six nipples. This mouse probably breeds throughout the year except during the coldest part of winter.