It has been captured throughout the year on trapping grids at Summerland in the Okanagan Valley. Diet or Growing requirements Dietary data are based on studies done in California and the Great Plains of the United States. Flowers, herbaceous material, and Endogone fungi are also consumed. Small caches of sectioned grass blades and stems may be found in runways occupied by harvest mice. In the late summer and fall, the diet consists mainly of seed from grasses and forbs .
Some food is stored away against the arrival of inclement weather.
Harvest mice also eat insects such as moths and grasshoppers. The average food consumption has been found to be 1.63 g of oats per day. The arboreal activity of R. megalotis in shrubs is probably related to foraging for seeds, flowers, and invertebrates. Habitat Conservation Fund, August 1992 Banfield, A.W.F. 1974. Mammals of Canada.