1. Centre for Biological Diversity, School of Biology, University of St Andrews, St Andrews KY16 9TH, UK
2. Cognitive and Cultural Ecology Research Group, Max Planck Institute of Animal Behavior, Am Obstberg 1, 78315 Radolfzell am Bodensee, Germany
3. Helsinki Institute of Life Science HiLIFE, University of Helsinki, 00014 Helsinki, Finland
4. School of Psychology and Neuroscience, University of St Andrews, St Andrews KY16 9JP, UK