Affiliation: | 1. Addresses of authors: Hendrik van Viandenstraat 66, 8266 DS Kampen, The Netherlands;2. Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Summerhall, Edinburgh EH9 1QH, Scotland, UK;3. Royal Zoological Society of Scotland, 134 Corstorphine Road, Edinburgh EH12 6TS, Scotland, UK |