The Phenology of the Common Swift Apus apus in Eurasia and the Problem of Defining the Duration of their Stay
This paper is dedicated to the first phenologist, the author of the Book Jeremiah (Jeremiah 8.7).
(Printed 2007 in Podoces. Republished with permission.)
More arrival data: http://www.commonswift.org/arrival.html
Original paper: http://www.wesca.net/Podoces/Podoces2.2/Podoces 2_2_ Phenology of Common Swift.pdf