Citation
Eaton, M.A., Balmer, D.E., Bright, J., Cuthbert, R., Grice, P.V., Hall, C., Hayhow, D.B., Hearn, R.D., Holt, C.A., Knipe, A., Mavor, R., Noble, D.G., Oppel ,S., Risely, K., Stroud, D.A. & Wotton, S. 2014. The State of the UK's Birds 2013. RSPB, BTO, WWT, NRW, JNCC, NE, NIEA & SNH, Sandy, Bedfordshire