1. Institute of Zoology; Zoological Society of London; Regent's Park London NW 1 4RY UK
2. Smithsonian Tropical Research Institute; Panamá City Panamá
3. North Carolina State University and Museum of Natural Sciences; Raleigh NC USA
4. Department of Migration and Immuno-Ecology; Max Planck Institute for Ornithology; Radolfzell Germany
5. Department of Biology; University of Konstanz; Konstanz Germany
6. Department of Environmental Sciences; Wageningen University; Wageningen The Netherlands