About Cypseloides senex (Temminck, 1826)
The great dusky swift, with the scientific name Cypseloides senex (Temminck, 1826), is the largest species in the genus Cypseloides. It measures 18 cm (7.1 in) long and weighs between 56 and 110 g (2.0 to 3.9 oz). Males and females have identical plumage. Adult great dusky swifts have chocolate brown crowns and throats, with pale gray feather edges that create a frosted look on the face. Their back is darker brown, their rump is an intermediate brown shade between the color of the head and the back, and their tail is blackish brown. Their undersides are paler brown than their back. The upper side of the wing is mostly brown, and the underside is somewhat lighter. Juveniles closely resemble adults, but have additional pale fringes on their wing feathers. The great dusky swift is distributed in Brazil, ranging from southern Pará and most of Mato Grosso east to Bahia and south to Rio Grande do Sul, as well as in eastern Paraguay and Misiones Province in northeastern Argentina. Undocumented sight records from Bolivia mean the South American Classification Committee of the American Ornithological Society classifies the species as hypothetical in that country. Its main habitats are tropical evergreen forest, temperate forest, and second-growth scrubland. This species roosts near waterfalls, and is known to fly through Iguazu Falls, located on the border between Brazil and Argentina.
