1. School of Biological Sciences; University of East Anglia; Norwich Research Park; Norwich; NR4 7TJ; UK
2. University of Iceland; South Iceland Research Centre; Tryggvagata 36; Selfoss; IS-800 ; Gunnarsholt; Hella; IS-851; Iceland
3. Farlington Ringing Group; Solent Court Cottage; Chilling Lane; Warsash; Southampton; SO31 9HF; UK
4. Department of Zoology; Conservation Science Group; University of Cambridge; Downing St; Cambridge; CB2 3EJ; UK