1. Institute of Forest Ecology Department of Forest and Soil Sciences University of Natural Resources and Life Sciences Vienna Austria
2. Cornell Lab of Ornithology Ithaca NY USA
3. Smithsonian Migratory Bird Center National Zoological Park Washington DC USA
4. Department of Systematic Zoology Adam Mickiewicz University Poznań Poland
5. Population Ecology Lab Faculty of Biology Adam Mickiewicz University Poznań Poland
6. Department of Forest Ecology Forest Research Institute Raszyn Poland
7. Department of Silviculture and Genetics of Forest Trees Forest Research Institute Raszyn Poland
8. CREAF Cerdanyola del Vallès Catalonia Spain
9. PLECO (Plants and Ecosystems) Department of Biology University of Antwerp Wilrijk Belgium