1. Centre for Ecology and Hydrology, Hill of Brathens, Banchory AB31 4BW, UK
2. 2University Courses on Svalbard (UNIS), Longyearbyen, N-9170, Norway
3. 3Department of Biological and Molecular Sciences, University of Stirling, Stirling FK9 4LA, UK
4. 4Norwegian Institute for Nature Research (NINA), Tunasletta–2, Trondheim, N-7040, Norway
5. 5Norwegian College of Veterinary Medicine, Ullevalsveien 72, PO Box 8146, N–0033 Oslo, Norway
6. University of Olso, Zoological Museum, Sarsgate 1, N–0562 Oslo, Norway