The Rothschild’s Swift was long considered to be conspecific with the Sooty Swift (Cypseloides fumigatus), which species is largely confined to southeastern South America. Like other Cypseloides species, Rothschild’s Swift is a medium-sized swift with long, broad wings, and a short square-ended tail. Its plumage is entirely mid brown; in the field separation from Sooty Swift is probably impossible, except on distribution. The present species is more or less confined to northwest Argentina, although it probably ranges narrowly into Bolivia; there are no records from Peru, despite many assertions in the literature to the contrary. Very poorly known indeed, virtually nothing has been published concerning the Rothschild’s Swift’s ecology and behavior.