Colymbus immer
Regular winter visitor, sometimes numerous in Milford Haven, mostly immatures. Frequently seen near the islands and on the open coast. occasionally remaining late in spring - a male in breeding plumage washed ashore at Saundersfoot, May 1927; and another seen Fishguard Harbour, mid-May 1930 (Bertram Lloyd)
R.M.Lockley, G.C.S.Ingram, H.M.Salmon, 1949, The Birds of Pembrokeshire, The West Wales Field Society