1. Max Planck Institute for Ornithology, Seewiesen, Germany
2. Department of Biology, University of Konstanz, Konstanz, Germany
3. Department of Animal Ecology, Netherlands Institute of Ecology, Wageningen, The Netherlands
4. Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, UK
5. Department of Biological Sciences and Center for Bioengineering Innovation, Northern Arizona University, Flagstaff, AZ, USA
6. Department of Arctic and Marine Biology, UiT: the Arctic University of Norway, Tromsø, Norway
7. Department of Biological Sciences, North Dakota State University, Fargo, ND 58102, USA
8. Chronobiology unit, Groningen Institute for Evolutionary Life Sciences, University of Groningen, The Netherlands