1. Wrocław University, Ornithological Station, Sienkiewicza 21, Wrocław 50-335, Poland
2. Wrocław University, Department of Behavioural Ecology, Sienkiewicza 21, Wrocław 50-335, Poland
3. Silesian Ornithological Society, Sienkiewicza 21, 50-335 Wrocław, Poland
4. Białobrzegi 106, 22-400 Zamość, Poland
5. Public Primary School 15, Hirszfelda 1, 58-309 Wałbrzych, Poland
6. Chełmy Countryside Park, Myślibórz 11, 59-411 Myślibórz, Poland