1. School of Biological Sciences, University of East Anglia; Norwich Research Park; Norwich NR4 7TJ United Kingdom
2. NERC Biomolecular Analysis Facility, Department of Animal and Plant Sciences; University of Sheffield; Sheffield S10 2TN United Kingdom
3. Max Planck Institute for Ornithology; 82319 Seewiesen Germany
4. Earlham Institute; Norwich Research Park; Norwich NR4 7UZ United Kingdom