1. Institute of Agricultural Sciences, ETH Zürich, Universitätsstrasse 2, 8092 Zurich, Switzerland
2. Behavioural Ecology Group, Section for Ecology & Evolution, Department of Biology, University of Copenhagen, 2100 Copenhagen Ø, Denmark
3. Wildlife Ecology & Conservation Group, Wageningen University and Research, 6708PB Wageningen, The Netherlands
4. Swiss National Stud Farm, Agroscope, Les Longs-Prés, 1580 Avenches, Switzerland