1. Royal Society for the Protection of Birds; The Lodge Sandy Bedfordshire SG19 2DL UK
2. Institute of Avian Research; ‘Vogelwarte Helgoland’; An der Vogelwarte 21 26386 Wilhelmshaven Germany
3. Pan-European Common Bird Monitoring Scheme; Czech Society for Ornithology; Na Bělidle 252/34 CZ-150 00 Prague 5 Czech Republic