Sterna albifrons albifrons

Occasionally seen on passage, as in Mathew’s time, chiefly offshore between Grassholm and the mainland. 

One Skokholm, 24 June 1936. Six fishing in Solva harbour (one shot) 8 May 1916 (H.W.Evans)

R.M.Lockley, G.C.S.Ingram, H.M.Salmon, 1949, The Birds of Pembrokeshire, The West Wales Field Society

More about the Little Tern in Pembrokeshire