1. 1Reptile, Amphibian and Fish Conservation the Netherlands, P.O. Box 1413, 6501 BK Nijmegen, The Netherlands
2. 4Department of Pathology, Bacteriology and Avian Diseases, Ghent University, Salisburylaan 133, B-9820 Merelbeke, Belgium
3. 2Statistics Netherlands, P.O. Box 24500, 2490 HA Den Haag, The Netherlands
4. 3Dutch Wildlife Health Centre, Utrecht University, P.O. Box 80158, 3508 TD Utrecht, The Netherlands