1. Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada.
2. Department of Environment, Health, and Safety, University of Insubria, Varese, Via J. H. Dunant 3, I-21100 Varese, Italy.
3. Ecology, Evolutionary Biology, and Behavior Program, Department of Fisheries and Wildlife, Department of Zoology, 13 Natural Resources Building, Michigan State University, East Lansing, MI 48824, USA.
4. Natural Resource Sciences, Macdonald Campus, McGill University, Ste-Anne-de-Bellevue, Québec H9X 3V9, Canada.
5. Laboratory of Ornithology, Cornell University, 159 Sapsucker Woods Road, Ithaca, NY 14850–1999, USA.