The Mexican Whip-poor-will is a medium-sized, predominantly brownish nightjar that is found from the southwestern United States south to El Salvador. This species is migratory in northern portions of its range (including the breeding population of the United States), but is resident in the southern two-thirds of its range. Its plumage is nearly identical to that of the Eastern Whip-poor-will (Caprimulgus vociferus), but the two species probably overlap only in winter, in eastern Mexico and Central America. These two whip-poor-wills formerly were classified as a single species; they differ slightly in morphology, vocalizations (slower and more burry in the present species), and egg pigmentation. Mexican Whip-poor-will breeds in forested areas between sea level and 3000 m, mainly in February to July.