1. Behavioural Ecology and Sociobiology Unit, German Primate Center, Leibniz Institute for Primatology, Kellnerweg 4, 37077 Göttingen, Germany
2. Department of Sociobiology/Anthropology, Johann-Friedrich-Blumenbach Institute for Zoology and Anthropology, University of Göttingen, Kellnerweg 6, 37077 Göttingen, Germany
3. Leibniz ScienceCampus ‘Primate Cognition’, Göttingen, Germany