Common Swift (Apus apus) Science Article 4
abstract
The spermatozoon of Apus apus is typical of non-passerines in many respects. Features shared with palaeognaths and the Galloanserae are the conical acrosome, shorter than the nucleus
Barrie G. M. Jamieson and Sandro Tripepi, Acta Zoologica (Stockholm) 86: 239-244 (October 2005)