Breast feathers disarranged showing dark bases. This species breeds only in southern South America. Its specific epithet is disputed with HBW using T. meyeni, while Clements, IOC and Howard & Moore have reverted to T. leucopyga. The question is whether T. leucopyga is preoccupied, but the case made by Mlkovsk & Frahnert would seem to be unassailable. Chilean Swallow forms a superspecies with White-rumped Swallow (T. leucorrhoa) which replaces it to the northeast. The two are allopatric during the breeding season. Chilean Swallow lacks the white supraloral streak of White-rumped.