1. National Veterinary Institute, PO Box 750, Sentrum, NO-0106 Oslo, Norway
2. Current address: National Veterinary Institute, Regional Office in Sandnes, PO Box 295, NO-4303 Sandnes, Norway
3. Norwegian Institute for Nature Research, NO-7485 Trondheim, Norway
4. Norwegian Polar Institute, Polar Environmental Centre, NO-9296 Tromsø, Norway
5. Hedmark University College, Faculty of Forestry and Wildlife Management, Campus Evenstad, NO-2418 Elverum, Norway
6. Swedish Agricultural University, Faculty of Forestry, Department of Wildlife, Fish and Environmental Studies, SE-90183 Umeå, Sweden