1. Centre for Ecology and Conservation, University of Exeter, Cornwall Campus, Penryn, UK
2. UK Centre for Ecology and Hydrology, Benson Lane, Crowmarsh Gifford, Wallingford OX10 8BB, UK
3. Oxford Martin School and School of Geography and Environment, University of Oxford, Oxford, OX1 3BD, UK
4. Department of Migration, Max Planck Institute of Animal Behavior, Radolfzell, Germany
5. Centre for the Advanced Study of Collective Behaviour, University of Konstanz, Konstanz, Germany
6. Department of Biology, University of Konstanz, Konstanz, Germany
7. School of Biological Sciences, The University of Western Australia, Crawley, Western Australia, Australia