Apus apus apus

Numerous summer visitor, breeding in castles, chapels, and tall buildings, also coastal cliffs (Caldey).  Considerable passage towards north-west and Ireland during May.

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

More about the Swift in Pembrokeshire