This bat has been found in western and panhandle counties in Idaho, in a variety of habitats from forest to desert conditions. It appears to be more common in areas with open areas of slack water. Summer roosts include crevices in rocky hillsides, rocky outcrops, buildings, trees with exfoliating bark, and cavities in snags. California myotis eat small insects including moths, beetles, and flies. Periods of foraging activity may vary with temperature in this species and flight may occur during freezing conditions.
Colonies appears to be small.
Mine use may be limited, but the roosting requirements of this species needs further study. Mating takes place during the fall, excepting California where it may occur during the spring. A single pup is born. Nursery colonies are small, the largest found in Canada consisted of 52 individuals. Very little is known about this species in Idaho.