Low-tide distributions of waterbirds on the Severn estuary SPA : results of the 2002/03 WeBS low tide counts and a historical analysis = Dosbarthiad adar dŵr pan fo h'in ddistyll ar Aber yr Afon hafren AGA : canlynniadau AAyG 2002/03 o'r cyfrifon distyll ynghyd â dadansoddiad hanesyddol /
Burton, N. H. K.
British Trust for Ornithology.
Thetford : British Trust for Ornithology,
2003.
"Report of work carried out by the British Trust for Ornithology under contract to English Nature and the Countryside Council for Wales." - t.p.
November 2003.
Water birds
Waterfowl