1. Department of Migration Max Planck Institute of Animal Behavior Radolfzell Germany
2. Department of Biology University of Konstanz Konstanz Germany
3. Product Development Group Zurich (pd z) ETH Zürich Zürich Switzerland
4. Centre for the Advanced Study of Collective Behaviour University of Konstanz Konstanz Germany
5. Cognitive and Cultural Ecology Research Group Max Planck Institute of Animal Behavior Radolfzell Germany