1. Netherlands Institute of Ecology, PO Box 40, 6666ZG Heteren, The Netherlands
2. Institute of Biology, Karelian Research Centre, Russian Academy of Science, Pushkinskaya Street 11, 185610, Petrozavodsk, Russia
3. Larixlaan 12, 7955AE IJhorst, The Netherlands
4. Cardiff University School of Biosciences, Llysdinam Field Centre, Newbridge-on-Wye, Llandrindod Wells LD1 6ND, UK
5. Kuypersweg 3, 6871EC Renkum, The Netherlands
6. Section of Ecology, 20014 University of Turku, , Finland
7. Department of Zoology, University of Gothenburg, Box 463, SE 405 30 Gothenburg, Sweden
8. Evolutionary Biology Centre, Department of Animal Ecology, Norbyvägen 18D, SE–752 36 Uppsala, Sweden
9. Zvenigorod Biological Station of Moscow State University, PO Box Shikhovo, Odintsovo District, 143 036 Moscow, Russia
10. Kilpisjärvi Biological Station, University of Helsinki, PO Box 17, FIN-00014 Helsinki, Finland
11. Ornithology Group, Division of Environmental and Evolutionary Biology, Graham Kerr Building, Glasgow University, Glasgow G12 8QQ, UK
12. Department of Ecology and Environmental Science, Umeå University, Umeå S-901 87, Sweden
13. Department of Animal Biology, University of Alcalá, E-288871 Alcalá de Henares, Spain
14. Rue du Theu, CH-1446 Baulmes, Switzerland
15. Departamento de Ecología Evolutiva, Museo Nacional de Ciencias Naturales (CSIC), José Gutiérrez Abascal 2, 28006 Madrid, Spain
16. Cardiff School of Biosciences, Cardiff University, Cardiff CF10 1XL, UK
17. Biological Station Rybachy, Zoological Institute of the Russian Academy of Science, Rybachy 238535, Kaliningrad Region, Russia
18. Behavioural Ecology Group, Department of Systematic Zoology and Ecology, Eötvös Loránd University, Pázmány Péter sétány 1/C, H-1117 Budapest, Hungary
19. Institute of Avian Research ‘Vogelwarte Helgoland’, Working Group Population Ecology, Bauernstrasse 14, D-38162 Cremlingen, Germany
20. School of Biological Sciences, University of Wales, Bangor LL57 2UW, UK
21. Oberer Triftweg 31A, D–38640 Goslar, Germany