1. Departamento de Zoología, Universidad de Córdoba. Edificio Charles Darwin, Córdoba, Poland
2. Department of Zoology, Poznań University of Life Sciences, Poznań, Spain
3. Department of Avian Biology and Ecology, Faculty of Biology, Adam Mickiewicz University, Poznań, Poland
4. Institute of Nature Conservation, Polish Academy of Sciences, Kraków, Poland
5. Konrad Lorenz Institute of Ethology, University of Veterinary Medicine Vienna, Wien, Austria