1. Institute of Zoology; Zoological Society of London; Regents Park; London; NW1 4RY; UK
2. Department of Animal Physiology; University of Tübingen; Auf der Morgenstelle 28; D-72076; Tübingen; Germany
3. Department of Biology; Western University; London; ON; N6A 5B7; Canada
4. School of Biological Sciences; University of Bristol; Woodland Road; Bristol; BS8 1UG; UK
5. Biodiversity and Conservation Biology; Swiss Federal Institute for Forest; Snow and Landscape Research WSL; Zuercherstrasse 111; 8903; Birmensdorf; ZH; Switzerland
6. Sensory Ecology Group; Max Planck Institute for Ornithology; 82319; Seewiesen; Germany
7. School of Biological Sciences; University of Auckland; Private Bag 92019; Auckland; New Zealand