1. German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Puschstr. 4, 04103 Leipzig, Germany
2. Institute of Biodiversity, Friedrich-Schiller-University Jena, Jena, 07743, Germany
3. School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 4LB, UK
4. Department of Ecology & Evolutionary Biology, Cornell University, Ithaca, NY, 14853, USA
5. Cornell Laboratory of Ornithology, Ithaca, NY, 14850, USA