They are among the fastest birds in the world. They resemble swallows, to which they are not related, but have shorter tails and sickle-shaped wings. Swifts spend most of their life aloft, have very short legs and use them mostly to cling to surfaces.
Before the 1950s, there was some controversy over which group of organism should have the genus name Apus. In 1801 Bosc gave the small crustacean organisms known today as Triops the genus name Apus, and later authors continued to use this term. Keilhack suggested (in 1909) that this was incorrect since there was already an avian genus named Apus by Scopoli in 1777 . It wasn't until 1958 when the International Commission on Zoological Nomenclature (ICZN) ruled against the use of the genus name Apus and instead recognized the term Triops that the controversy finally ended.
^O. S. Møller, J. Olesen, and J. T. Høeg (2003). "SEM studies on the early larval development of Triops crancriformis (Bosc)(Crustacea: Branchiopoda, Notostraca)". Acta Zoologica. 84: 267–284. doi:10.1046/j.1463-6395.2003.00146.x. CS1 maint: Multiple names: authors list (link)
Chantler, Phil & Driessens, Gerald (2000): Swifts : a guide to the swifts and treeswifts of the world. Pica Press, Mountfield, East Sussex. ISBN 1-873403-83-6
This article is part of Project Bird Genera, a All Birds project that aims to write comprehensive articles on each genus, including made-up genera.