1Finnish Centre of Excellence in Metapopulation Biology, Department of Biosciences, P.O. Box 65, FI-00014 University of Helsinki, Finland
2Department of Biology, P.O. Box 373, University of York, York YO10 5YW United Kingdom
3Biodiversity and Macroecology Group, Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN United Kingdom
4School of Biological Sciences, University of Southampton, Life Sciences Building (B85), Highfield Campus, Southampton SO17 1BJ, United Kingdom
5Centre of Terrestrial Carbon Dynamics (York Centre), Stockholm Environment Institute at York and Environment Department, University of York, York YO10 5DD United Kingdom
6NERC Centre for Ecology and Hydrology, Wallingford, Oxfordshire OX10 8BB United Kingdom
7British Trust for Ornithology, The Nunnery, Thetford, Norfolk IP24 2PU, United Kingdom
8Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, Tennessee 37996-1601 USA