1. School of Natural Sciences, Bangor University, Bangor LL57 2UW, UK
2. Institute of Avian Research ‘Vogelwarte Helgoland’, Wilhelmshaven 26386, Germany
3. School of Life Sciences, Keele University, Newcastle-under-Lyme ST5 5BG, UK
4. Biological Station Lake Neusiedl, Illmitz 7142, Austria
5. Nationalpark Neusiedler See – Seewinkel, Apetlon 7143, Austria
6. Austrian Ornithological Centre, Konrad-Lorenz Institute of Ethology, University of Veterinary Medicine Vienna, 1160 Wien, Austria
7. Department of Zoology, Oxford University, Oxford OX1 3SZ, UK