1. Department of Animal Ecology, Netherlands Institute of Ecology (NIOO-KNAW) , Wageningen , The Netherlands
2. Behavioural Ecology Group, Wageningen University & Research (WUR) , Wageningen , The Netherlands
3. Department of Animal Behaviour, University of Bielefeld , Bielefeld , Germany
4. Department of Terrestrial Ecology, Netherlands Institute of Ecology (NIOO-KNAW) , Wageningen , The Netherlands