White-naped Swift is resident in highland regions of the Sierra Madre Occidental, Sierra Madre del Sur, and Transvolcanic Belt of Mexico. There are two apparently disjunct populations: one from southern Chihuahua to Jalisco in the Sierra Madre Occidental, and one from Michoacán to northwestern Oaxaca and the southern parts of the state of Mexico in the Sierra Madre del Sur and the Transvolcanic Belt, apparently crossing the Balsas Drainage. Casual in Chiapas near the Guatemalan border (Howell and Webb 1995, one individual), as well as groups from the Upper Rio Raspaculo, Belize. Unconfirmed sightings of flocks of large swifts with a white nape and distinct flight pattern from the Caribbean lowlands of Honduras may refer to White-naped. However, these observations date from 1952 and 1960, and a specimen was never obtained. There also are unconfirmed observations from Oaxaca and Hidalgo. It appears that the species is a year round resident in most of the Mexican part of the range, so it is unclear whether the birds from Belize and Chiapas represent vagrants, are part of migratory patterns, or pertain to local breeding populations. In parts of the Transvolcanic Belt (Distrito Federal), birds are absent during winter from August to March. The hiatus in the distribution of the species may reflect true absence due to lack of nesting or roosting habitats, or may be the result of a lack of observers in remote Mexican highlands. The habit of this species of flying very high could cause it to go unnoticed in lowland areas.