The masked bobwhite (Colinus virginianus ridgwayi) is an endangered species currently numbering \u3c1500 individuals and restricted to 2 locales in southeastern Arizona and northcentral Sonora, Mexico. The subspecies\u27 endangered status is attributed to overgrazing of Sonora savanna grassland that began during the late 1880\u27s and continued well into the 20th century. This overgrazing resulted in the conversion of many native grass pastures to the exotic bufflegrass (Cenchrus ciliaris). The Arizona masked bobwhite population was extirpated around the turn of the century, and the Sonoran population was thought to have disappeared during the 1940\u27s until a small remnant population was discovered on a ranch near Benjamin Hill, Sonora , in 1964 . Masked bobwhite recovery efforts have a dynamic, long history of nearly six decades. Current masked bobwhite recovery efforts focus on reestablishing a self-sustaining population on the Buenos Aires National Wildlife Refuge (BANWR) in the United States, as well as 2 remnant wild populations located on privately owned ranches in northcentral Sonora
