1. Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences Tartu, Estonia
2. Faculty of Biology, University of Białystok, Białystok, Poland
3. Vygonoshchanskoye Republican Landscape Reserve, Telechany, Belarus
4. Working Group on Raptors and Owls, APB-Birdlife-Belarus, Minsk, Belarus
5. Nature Society ‘Dubelt’, Michałowo, Poland