1. Department of Biology; Center for Ecology, Evolution, and Behavior, University of Kentucky; 101 Morgan Building Lexington KY 40506-0225 U.S.A.
2. Department of Biology; Center for Biodiversity Dynamics, Norwegian University of Science and Technology (NTNU); N-7491 Trondheim Norway
3. Behavioural Ecology, Department of Biology; Ludwig-Maximilians University of Munich; Planegg-Martinsried Germany
4. Evolutionary Ecology of Variation Research Group, Max Planck Institute for Ornithology; Seewiesen Germany