1. Reptile, Amphibian & Fish Conservation Netherlands (RAVON); P.O. Box 1413, 6501 BK Nijmegen the Netherlands
2. Faculty of Veterinary Medicine; Department of Pathology; Bacteriology and Avian Diseases; Ghent University, Salisburylaan 133; B9820 Merelbeke Belgium
3. Dutch Centre for Field Ornithology (SOVON), Toernooiveld 1; 6525 ED Nijmegen the Netherlands
4. Experimental Plant Ecology; Institute for Water and Wetland Research; Radboud University Nijmegen; P.O. Box 9100, 6500 GL Nijmegen the Netherlands
5. Institute of Zoology; Zoological Society of London; London NW1 4RY United Kingdom
6. Natuurpunt-Hyla, Coxiestraat 11; 2800 Mechelen Belgium