1. Centre for Macroecology, Evolution and Climate, Globe Institute, University of Copenhagen, Universitetsparken 15, DK-2100 Copenhagen
2. Max Planck Institute of Animal Behaviour, Am Obstberg 1, 78315 Radolfzell, Germany
3. Skagen Bird Observatory, Birdlife Denmark, Fyrvej 36, DK-9990 Skagen
4. Department of Chemistry and Bioscience, Aalborg University, Fredrik Bajers Vej 7H, 9220 Aalborg
5. Natural History Museum of Denmark, University of Copenhagen, Øster Voldgade 5-7, DK-1350 Copenhagen