North America, 4th ed. . Sibley, David Allen (2014). The Sibley Guide to Birds, 2nd ed. New York: Knopf. . External links Elf Owl photo gallery Cornell Lab of Ornithology entry for the Elf owl. Includes photograph and audio recording. Elf owl fact sheet from the Arizona-Sonora Desert Museum. elf owl Native birds of the Southwestern United States Birds of the Rio Grande valleys Birds of Mexico elf owl Natural history of the Revillagigedo Islands elf owl elf owl Birds of the Sierra Madre Occidental Birds of the Trans-Mexican Volcanic Belt Fauna of the Sonoran Desert