Hayhow D.B., Ausden M.A., Bradbury R.B., Burnell D., Copeland A.I., Crick H.Q.P., Eaton M.A., Frost T., Grice P.V., Hall C., Harris S.J., Morecroft M.D., Noble D.G., Pearce-Higgins J.W., Watts O., Williams J.M. 2017. The State of the UK's Birds 2017. RSPB, BTO, WWT, DAERA, JNCC, NE and NRW, Sandy, Bedfordshire