1. Centre for Biodiversity Dynamics Department of Biology Norwegian University of Science and Technology 7491 Trondheim Norway
2. Centre for Biodiversity Dynamics Department of Mathematical Sciences Norwegian University of Science and Technology 7491 Trondheim Norway
3. Evolutionary Ecology Group University of Antwerp Wilrijk2610 Belgium
4. Laboratory of Ornithology Cornell University Ithaca NY14850 USA
5. Edward Grey Institute Department of Zoology University of Oxford OxfordOX1 3PS UK