The Common Swift Apus apus (LINNAEUS 1758) belongs within the class Birds / Aves to the swifts, which are grouped together as the order Apodiformes. Carl von Linné, who introduced the binomial (binary) naming system for species beginning with the 10th edition of his "Systema Naturae" in 1758 (BEZZEL and PRINZINGER, 1990), classified the Common Swift among the swallows. It can be found there under the name Hirundo apus (LINNAEUS 1758). The genus Apus was introduced by Scopoli in 1777 (GLUTZ and BAUER, 1980). Later, the genus names Micropus and Cypselus were also used but did not prevail. The scientific name Apus apus used here is identical to that in GLUTZ and BAUER (1980) and in the most recent world list of birds by DICKINSON (2003).
WOLTERS (1975–1982) places the Apodiformes as most closely related to the hummingbirds, Trochiliformes. SIBLEY and AHLQUIST (1990) confirm the assumption of a closer relationship using DNA hybridization, which WOLTERS could not yet utilize, but combine the two monophyletic sister groups swifts, Apodiformes and hummingbirds, Trochiliformes into a superorder Apodimorphae. Somewhat later, CHANTLER (in DEL HOYO et al., 1999) places swifts and hummingbirds in one order Apodiformes with the two suborders Apodi and Trochili. There is agreement on the classification into families.
SIBLEY and AHLQUIST (1990) divide the order Apodiformes into two families: Apodidae, true swifts, with about 94 currently recognized species (DICKINSON 2003) and Hemiprocnidae, tree swifts, with 4 species. The taxonomy at the level of genera and species is not yet completely and undisputedly clarified. Particularly in the large genus Collocalia, Swiftlets, the species boundaries are still partially unclear. The same applies to some African species of the genus Apus.
New insights from molecular genetic studies are expected in the near future, especially for groups that have barely been studied so far. In general, in ornithology, taxonomy at the level of species and subspecies has become very dynamic in connection with different species concepts and especially under the aspect of the superspecies concept, so alternative proposals are to be expected. In particular, species numbers per genus should only be considered as a current proposal. In some areas (tropical Asia, Central Africa), discoveries of previously unknown species are also not unlikely.
Swifts originated in tropical climates and then evolved into Old World and New World subfamilies with the breakup of the Gondwana continent, with the Cypseloidinae in South and North America and the Apodinae in Africa, Europe and Asia. The genus Apus is distributed throughout the Old World, but most species occur in Africa, with 6 species being endemic to sub-Saharan Africa. Today, swifts are cosmopolitan except for very high latitudes. Two factors have made this possible: The extreme association with human settlements of some species through nest site selection in urban areas and the evolution to long-distance migrants. The young as extreme nest-bound birds with the ability to enter hunger torpor can be successfully raised even in higher latitude climates with uncertain summer weather.