1. Conservation Ecology Group, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, The Netherlands
2. Department of Behavioural Ecology and Evolutionary Genetics, Max Planck Institute for Ornithology, Seewiesen, Germany
3. Department of Animal Behaviour, Bielefeld University, Bielefeld, Germany
4. Molecular Ecology and Evolution Lab, Lund University, Lund, Sweden