Although the Black-chinned Sparrow (Spizella atrogularis) is fairly widespread in the Southwest and locally abundant, it is one of the least studied passerines in North America (Tenne 1997). This is perhaps due to its preference for large tracts of undisturbed chaparral or successional scrub in remote and rugged terrain. Over much of its range its population density tends to be low and its occurrence is erratic. The main breeding populations are in southern to central California, Arizona, New Mexico, southern Nevada and Utah, southwestern Texas, and Mexico. Occasional irruptions are reported north as far as Oregon (Gilligan et al. 1994). The Black-chinned Sparrow is a partial migrant, with the distribution shifting southward during winter and into desert scrub mostly in northern to central mainland Mexico and Baja California Sur. As far as known, all populations breeding in the U.S. are migratory, and only a few birds winter in southern Arizona, southern New Mexico, and southwestern Texas. In southern California it is very rare as a winter visitor and as a migrant away from nesting habitat (Unitt 2004). Results of the North American Breeding Bird Survey suggest a national trend of overall decrease in Black-chinned Sparrow abundance of -5.4% per year 1966–2007 (P = 0.001), but many regions of its range are not adequately covered (Sauer et al. 2008).