Plain Swift (Apus unicolor) [XC164524]
by Lars Lachmann from Ponta Do Pargo, Madeira, Madeira, Portugal (flight call)
Plain Swift (Apus unicolor) [XC87333]
by Fernand DEROUSSEN from Machico, Madeira, Portugal (call)
Subspecies
Forms superspecies with Common Swift (Apus apus) and Nyanza Swift (Apus niansae) and has been considered conspecific with both, and also with African Swift (Apus barbatus). In past, considered conspecific with Alexander's Swift (Apus alexandri). Subspecies poensis of Scarce Swift (Schoutedenapus myoptilus) formerly treated as subspecies of this species.