In March 1997, the U.S. Fish and Wildlife Service listed the Arizona population of the cactus ferruginous pygmy-owl (Glaucidium brasilianum cactorum) as endangered under the Endangered Species Act (U.S. Fish and Wildlife 1997). Federal listing for the owl in Arizona resulted from a petition submitted in 1992 to the U.S. Fish and Wildlife Service (Galvin et al. 1992, U.S. Fish and Wildlife 1994).