1. University of Konstanz 1 Department of Biology , , 78457 Konstanz , Germany
2. Max Planck Institute of Animal Behavior 2 Department of Collective Behavior , , 78464 Konstanz , Germany
3. IMPRS for Quantitative Behaviour, Ecology and Evolution 3 , 78315 Radolfzell , Germany
4. Centre for the Advanced Study of Collective Behaviour, University of Konstanz 4 , 78464 Konstanz , Germany