ULRICH TIGGES:

The Breeding Cycle in Calendar Form of the Common Swift Apus apus across its Eurasian Breeding Range – A Testable Hypothesis?

(Printed 2006 in Podoces. Republished with permission.)

ISSN 1438-2261

The Commonswift Calendar: http://www.commonswift.org/The-Swift-Calendar.html

Original paper: http://www.wesca.net/Podoces/podoces1.html