The grey-rumped swift or gray-rumped swift (Chaetura cinereiventris) is a species of bird in subfamily Apodinae of the swift family Apodidae. It is found in Honduras, Nicaragua, Costa Rica, and Panama; in every mainland South American country except Chile, French Guiana, Suriname, and Uruguay; in Trinidad and Tobago; and on Grenada. Taxonomy and systematics The grey-rumped swift has these seven subspecies: C. c. phaeopygos Hellmayr, 1906 C. c. lawrencei Ridgway, 1893 C. c. schistacea Todd, 1937 C. c. guianensis Hartert, E.J.O., 1892 C. c. occidentalis Berlepsch & Taczanowski, 1884 C. c. sclateri Pelzeln, 1868 C. c. cinereiventris Sclater, P.L., 1862 The grey-rumped swift, pale-rumped swift (C. egregia), band-rumped swift (C. spinicaudus), and Lesser Antillean swift (C. martinica) were at one time placed in genus Acanthylis. Some authors have suggested that the grey-rumped and pale-rumped swifts are conspecific. Others have suggested that all of the grey-rumped subspecies except the nominate C. c. cinereiventris belong to another species under the binomial C. sclateri. Description The grey-rumped swift is about long and weighs about . It has a protruding head, a short square tail, and wings that bulge in the middle and somewhat hook at the end. The sexes are alike. Adults of the nominate subspecies have mostly glossy black upperparts with a wide gray rump and uppertail coverts. Their underparts are a lighter gray than the rump, though darker on the undertail coverts. Juveniles are essentially the same as adults with the addition of pale fringes to many of the wing feathers. Subspecies C. c. phaeopygos differs from the nominate only by having pale undertail coverts. C. c. lawrencei has slightly darker underparts than the nominate and black undertail coverts that contrast with the belly. C. c. schistacea has darker upperparts than the nominate, with a steely blue gloss, and also deep gray underparts. C. c. guianensis is almost identical to the nominate. C. c. occidentalis and C. c. sclateri have the darkest rumps of all the subspecies and blackish gray bellies. Distribution and habitat The subspecies of grey-rumped swift are found thus: C. c. phaeopygos, northeastern Honduras and from eastern Nicaragua through Costa Rica into northwestern Panama C. c. lawrencei, northern Venezuela, Trinidad, Tobago, and Grenada C. c. schistacea, the Andes from western Venezuela's Mérida state into eastern Colombia's Boyacá Department C. c. guianensis, eastern Venezuela and western Guyana C. c. occidentalis, from western Colombia through western Ecuador into extreme northwestern