Citation
Eaton, M.A., Balmer, D., Burton, N., Grice, P.V., Musgrove, A.J., Hearn, R., Hilton, G., Leech, D., Noble, D.G., Ratcliffe, N., Rehfisch, M.M., Whitehead, S. & Wotton, S. 2008. The State of the UK's Birds 2007. RSPB, BTO, WWT, CCW, EHS, NE and SNH, Sandy, Bedfordshire.