Great dusky swift
The great dusky swift is a South American species of swift in the family Apodidae. At 18 cm in length, it is large relative to other swifts, and dark brown in colour with a pale coloured head.
It is found in Brazil and far northeastern areas of Bolivia, Paraguay and Argentina. Its natural habitats are temperate forests, subtropical or tropical moist lowland forests, and heavily degraded former forest. Its very large distribution means that it is classified by IUCN as "least concern".
Flocks of these birds are known for flying through the Iguazu Falls on the border of Brazil and Argentina, and perching on the vertical cliff faces behind the falls.
