California bats have a wide tolerance of habitat including semi-arid desert regions of the Southwest, arid grasslands, forested regions of the Pacific Northwest, humid coastal forests and montane forests (Banfield 1974, Nagorsen and Brigham 1993). There is little documented information available on reproduction and ontongeny in M. californicus. It is known that mating occurs in autumn. A single young is born in late June or early July. The young develop rapidly and can fly about one month after birth. California bats have a potential reproductive lifespan of 15 years (Nagorsen and Brigham 1993, Simpson 1993, Wilson and Ruff 1999). California bats are insectivorous, feeding mainly on flies, moths and beetles. They forage only on insects in flight and are slow, acrobatic flyers, detecting prey at close range (less than 1 meter) and using echolocation calls during approach. Specific diet remains constant throughout the year, but likely varies from area to area. In British Columbia, M. californicus has been observed feeding mainly on Trichoptera and some Coleoptera, while further south, in Oregon, consumption consists primarily of Lepidoptera and Diptera (Banfield 1974, Fenton and Bell 1979, Simpson 1993, Wilson and Ruff 1999). Found in roofs in Guatemala (Sergio Perez pers. comm.)

This species occurs from southern Alaska Panhandle (USA) to Baja California and higher elevations in the Sonoran and Chihuahuan deserts (Mexico), also in Guatemala (Simmons 2005).

This species is found in a number of protected areas through Canada, the United States, and Mexico, but not in Guatemala.