The white-collared swift (Streptoprocne zonaris) is a species of bird in subfamily Cypseloidinae of the swift family Apodidae. It is found in Mexico, the Greater and Lesser Antilles, Trinidad, and every mainland South America country except Uruguay. The white-collared swift is the largest species of swift in its range except in northwestern Mexico, where it and the slightly larger white-naped swift (S. semicollaris) are sympatric. It has a wingspan of 45 to 55 cm (18 to 22 in). It has a very slightly forked tail and the sexes have the same plumage. Adults have a white collar that circles the neck and is broadest on the breast. Their forehead is sooty, most of the head dark sooty black, the tail grayish black, and the rest of the plumage black. The back, rump, and uppertail coverts have a slight blue gloss. Juveniles are duller and sootier than adults and have grayish white to white tips on most of their body feathers. There are minor differences among the subspecies in the width of the white collar, the shades of black on the body and tail, and the amount of white fringing on the juvenile.