1. Department of Ecology and Evolutionary Biology, Princeton University, Princeton, United States
2. Department of Collective Behaviour, Max Planck Institute for Ornithology, Konstanz, Germany
3. Department of Biology, Chair of Biodiversity and Collective Behaviour, University of Konstanz, Konstanz, Germany
4. Department of Zoology, Edward Grey Institute of Field Ornithology, University of Oxford, Oxford, United Kingdom
5. Department of Anthropology, University of California, Davis, Davis, United States
6. Animal Behaviour Graduate Group, University of California, Davis, Davis, United States
7. Smithsonian Tropical Research Institute, Panama