Delichon urbica urbica
Summer resident, less common than swallow. Nests on coastal cliffs in several places, eg near Newport, Moylgrove, Penrhyn Castle, Bosherston and at Caldey. Considerably less numerous on passage than Swallow.
R.M.Lockley, G.C.S.Ingram, H.M.Salmon, 1949, The Birds of Pembrokeshire, The West Wales Field Society