1. Humboldt Research Group “Evolution of Communication”; Max Planck Institute for Ornithology; Seewiesen Germany
2. Department of Cognitive Biology; University of Vienna; Vienna Austria
3. Haidlhof Research Station; University of Vienna and University of Veterinary Medicine; Vienna Austria
4. Humboldt Research Group; Department of Linguistic and Cultural Evolution; Max Planck Institute for the Science of Human History; Jena Germany