Baillie, S.R., Marchant, J.H., Leech, D.I., Joys, A.C., Noble, D.G., Barimore, C., Grantham, M.J., Risely, K. & Robinson, R.A. 2009. Breeding Birds in the Wider Countryside: their conservation status 2008. British Trust for Ornithology, Thetford, Norfolk