1. Museum and Institute of Zoology, Polish Academy of Sciences Wilcza 64 Warsaw 00‐679 Poland
2. Evolutionary Biology and Ecology, Institute of Biology I (Zoology) University of Freiburg Hauptstrasse 1 Freiburg 79104 Germany
3. Michael‐Otto‐Institut im NABU Goosstroot 1 Bergenhusen 24861 Germany
4. Department of Behavioural Ecology, Faculty of Biological Sciences University of Wrocław Sienkiewicza 21 Wrocław 50‐335 Poland
5. Association pour la Connaissance et la Recherche Ornithologique Loire et Atlantique (ACROLA) 10 rue de la Paix Donges 44480 France
6. Max Planck Institute of Animal Behavior Am Obstberg 1 Radolfzell 78315 Germany
7. Institut für Pharmazie und Molekulare Biotechnologie Heidelberg University Im Neuenheimer Feld 329 Heidelberg 69120 Germany