1. Avian Ecophysiology Unit, Department of Vertebrate Ecology and Zoology, Faculty of Biology, University of Gdańsk, Gdańsk, Poland
2. Bird Migration Research Station, Faculty of Biology, University of Gdańsk, Gdańsk, Poland
3. Bird Migration Research Foundation, Choczewo, Poland
4. Rakutowskie Bird Ringing Station, Students Naturalists Association of the Jagiellonian University, Faculty of Biology, Jagiellonian University, Kraków, Poland
5. Institute of Biodiversity and Ecosystem Research, Bulgarian Academy of Sciences, Sofia, Bulgaria