1. Behavioral Ecology and Sociobiology Unit, German Primate Center, Kellnerweg 4, 37077 Göttingen, Germany
2. Institut des Sciences de l'Evolution de Montpellier (ISEM), UMR5554 - University of Montpellier/CNRS/IRD/EPHE, Place Eugène Bataillon, 34095 Montpellier Cedex 5, France
3. Department for the Ecology of Animal Societies, Max Planck Institute of Animal Behavior, Bücklestrasse 5, Konstanz 78467, Germany