Aythya fuligula
Mathew describes it as a common winter visitor, which may occaionally remain to nest and says that great numbers frequented the shallows of Goodwick Bay in winter. There is, however, no evidence of breeding, even at Orielton, where as many as 150 have been seen at one time in winter, and in 1936 one pair remained thoughout the summer, but no nest was found (H.A.Gilbert)
R.M.Lockley, G.C.S.Ingram, H.M.Salmon, 1949, The Birds of Pembrokeshire, The West Wales Field Society