Peru's Tumbes department C. c. sclateri, patchily in southern Venezuela, southern Colombia, northwestern Brazil's upper Amazon basin, eastern Peru, and northwestern Bolivia C. c. cinereiventris, southeastern Brazil south from Bahia through eastern Paraguay into Argentina's Misiones Province The grey-rumped swift inhabits a variety of landscapes including lowland tropical evergreen forest, montane evergreen forest, seasonally flooded tropical evergreen forest, and secondary forest. In elevation it ranges from sea level to . Behavior Migration The grey-rumped swift is a year-round resident in most or all of its range. In Paraguay and Argentina it is possibly only a breeding species but there is evidence that it is resident there as well. Feeding Like all swifts, the grey-rumped is an aerial insectivore. It usually forages in flocks, typically of 20 to 40 birds. The flocks may be of it alone but may also have a mix of swift species and even swallows. Its diet includes flying ants, bees, wasps, beetles, and flies. Breeding The grey-rumped swift's breeding season varies throughout its range; examples are between September and March in southeastern Brazil and March to July in Costa Rica. It builds a half-cup nest on the vertical interior wall of a chimney or similar structure; it may be rebuilt and reused. Both parents incubate the clutch of two to four eggs at night. The incubation period and time to fledging are not known. Vocalization The principal vocalizations of the grey-rumped swift's nominate subspecies are "a bright repeated short 'tsip'" and a "series of 3–4 slightly downslurred burry drawn-out notes 'trrreeew-trrreeew-trrreeew'." The other subspecies' vocalizations vary but are similar to them. Status The IUCN has assessed the grey-rumped swift as being of Least Concern. It has an extremely large range and an estimated population of 50 million mature individuals. The population is believed to be slowly decreasing. No immediate threats have been identified. It is "[o]ne of the commonest Chaetura swifts throughout [its] range", is abundant in some areas, and occurs in several protected areas. References grey-rumped swift grey-rumped swift Birds of Nicaragua Birds of Costa Rica Birds of Colombia Birds of Ecuador Birds of Venezuela Birds of the Amazon Basin Birds of the Peruvian Amazon Birds of the Bolivian Amazon Birds of Trinidad and Tobago Birds of the Atlantic Forest grey-rumped swift grey-rumped swift