1. Ornithology Group, Graham Kerr Building, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ, United Kingdom
2. Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Road NW, Washington, D.C. 20015, USA
3. Scottish Universities Research and Reactor Centre (SURRC), East Kilbride, Glasgow G75 0QF, United Kingdom