Since 1968 I have been studying and banding Macrotus californicus in the low deserts of California and Arizona. With a narrow thermal-neutral zone, this species doesn't hibernate or migrate, relying primarily on behavioral adaptations and roost selection. I will share insights into their social system including stable female groups, leks in the fall and delayed embryonic development. They glean large insects and lizards from vegetation using combinations of echolocation, vision and prey-produced sounds. Threats to this species include the exploration of caves and closure of mines, and the loss of foraging habitat through development, most recently solar farms.