at least 17 percent of Great Britain's breeding population Marsh harrier at least 15 percent of Great Britain's breeding population Mediterranean gull Bar-tailed godwit Eurasian golden plover Hen harrier Ringed plover Black-tailed godwit Grey plover knot pintail Common redshank Northern shoveler See also Swale (local government district) References External links English Nature page Description of Special Protection Area Map sources for Thames Estuary Channels of England Special Protection Areas in England Sites of Special Scientific Interest in Kent Nature Conservation Review sites The Swale Ramsar sites in England Straits of England National nature reserves in England