1. Research Institute of Wildlife Ecology, University of Veterinary Medicine, Vienna, Savoyenstrasse 1, A-1160 Vienna, Austria
2. Present address: Center for Fish and Wildlife Health, Institute of Animal Pathology, Länggassstrasse 122, CH-3012 Berne, Switzerland
3. Institute of Mathematical Statistics and Actuarial Sciences, University of Berne, Sidlerstrasse 5, CH-3012 Berne, Switzerland
4. Present address: Wildvet Projects, CH-3054 Schüpfen, Switzerland