Found throughout the southwestern United States and Mexico in arid upland habitats, the Black-throated Sparrow breeds as far north as Washington State. Although often quite common, this conspicuous bird is little known. A seedeater throughout the year, especially in winter, but during the breeding season often gleans insects from leaves and stems of shrubs. Some populations nesting at northern latitudes migrate long distances, while those breeding farther south migrate shorter distances.
Black-throated Sparrow territories tend to be large during courtship and nest-building, shrinking to a smaller area around the nest while parents are incubating and caring for young. The male sings from high perches, while the female builds the nest low in desert shrubs or cactus. Incubation and nestling periods are relatively short. Monsoon rains in mid-June through July can stimulate renewed nesting activity, prolonging the breeding season and often allowing a second brood.
Many accounts of the Black-throated Sparrow are anecdotal, but extensive information on distribution, island populations, song, foraging behavior, habitat, cowbird parasitism, and predation is available from studies in Baja California, the Gulf of California islands, New Mexico, and Arizona ( Banks 1963b , Raitt and Maze 1968 , Heckenlively 1970 , Delesantro 1978 , George 1987b , Zimmer 1993 , and Johnson and Van Riper 2004 ). The physiological adaptations of this species to the stresses of desert habitats have been the focus of studies by Smyth and Bartholomew ( Smyth and Bartholomew 1966 ) and Gordon ( Gordon 1968a ). Studies of reproductive and population biology, movement patterns, the effects of rainfall on breeding success, and energy budgets/metabolism are particularly needed.