1. School of Natural Sciences, Macquarie University, Sydney 2109, Australia
2. School of Biological Sciences, University of Bristol, Bristol BS8 1TQ, UK
3. Department of Interdisciplinary Life Sciences, Konrad Lorenz-Institute of Ethology, University of Veterinary Medicine, 1160 Vienna, Austria
4. Department of Behavioral & Cognitive Biology, University of Vienna, 1030 Vienna, Austria