Rissa tridactyla tridactyla
Abundant resident on Ramsey, Skomer, Grassholm, and south mainland cliffs (at Flimston etc). In 1946 there were c.1900 pairs on Skomer, and 115 pairs on Grassholm. It has never bred on Skokholm, but does so on St Margaret's Island.
R.M.Lockley, G.C.S.Ingram, H.M.Salmon, 1949, The Birds of Pembrokeshire, The West Wales Field Society