Western jumping mice are
omnivores, with the largest part of their diet consisting of the seeds of grasses and herbs. Less important food items include fruits, fungi, and insects. Population densities range from , with individual mice having home ranges between , with males generally having larger ranges than females. The feeding grounds of mice can be identified by small piles of grass stems stripped of their seeds, and by the presence of clear runways strewn with grass clippings. Their nests are constructed from grass fragments, and are concealed beneath vegetation or debris. but are only active for the summer months, hibernating for the rest of the year. In at least some areas, they spend between eight and ten months of the year hibernating. Predators include
bobcats,
weasels,
skunks,
raccoons, snakes and birds of prey. The mice flee predators by making a rapid series of long jumps, interspersed with short periods when they freeze in place. Although they normally move by making short hops and occasional leaps of up to , when startled, their leaps may reach along the ground, and into the air. ==Reproduction==