two closest relatives, the Oaxaca sparrow and rusty sparrow, being maintained as the genus Aimophila. In addition, this study suggested that the rufous-crowned sparrow may be more closely related to the brown towhees of the genus Pipilo than the other members of the historical genus Aimophila. The derivation of the current genus name, Aimophila, is from the Greek aimos/ἀιμος, meaning "thicket", and -philos/-φιλος, meaning "loving". The specific epithet is a literal derivation of the common name, derived from the Latin rufus, meaning "reddish" or "tawny", and -ceps, from caput, meaning "head". The bird is also occasionally referred to colloquially as the rock sparrow because of its preference for rocky slopes. Subspecies Twelve subspecies are generally recognized, although sometimes up to eighteen are named. A. r. ruficeps, the nominate subspecies, was described by Cassin in 1852. It is found in the coastal ranges of California and on the western slopes of the Sierra Nevada. This subspecies is darker and noticeably smaller than A. r. eremoeca and has distinct rufous-brown streaking on its upperparts. A. r. canescens was described by American ornithologist W. E. Clyde Todd in 1922, and it is found in southwestern California and northeast Baja California as far east as the base of the San Pedro Mártir. While the species itself is listed as of least concern, this subspecies is listed as a "species of special concern" by the California Department of Fish and Wildlife, signifying that this population is threatened with extinction. It appears to be extremely similar to A. r. ruficeps but is darker. A. r. obscura, described by Donald R. Dickey and Adriaan van Rossem in 1923, is found in the Channel Islands of California on Santa Cruz, Anacapa, and formerly on Santa Catalina. While the Santa Catalina population has not been observed since 1863, the subspecies seems to have colonized Anacapa Island. No records exist of them before 1940. This subspecies is similar to A. r. canescens but is darker. A. r. sanctorum was described by van Rossem in 1947. It was found on the Todos Santos Islands off the coast of northwest Baja California. This subspecies is believed to be extinct. This is the darkest of the coastal subspecies, especially on its underbelly. A. r. sororia was described by Robert Ridgway in 1898, and is found in the mountains of southern Baja California, specifically the Sierra de la Laguna. It is the palest of