Sterna macrura
It is no longer, as in Mathew's day, "seen commonly on passage in the spring and autumn". Once recorded Skokholm, 8 June 1938. One seen Goodwick, 13 Aug 1935 (Bertram Lloyd). During the widespread inshore passage of this species at the end of april 1947, about twenty were seen over Dale beach (J.F. and P.Garnett)
R.M.Lockley, G.C.S.Ingram, H.M.Salmon, 1949, The Birds of Pembrokeshire, The West Wales Field Society