Clangula hyemalis

Mathew records two immatures shot at Stackpole, and an adult male shot at Haverfordwest, 15 June 1843. 

One female shot Milford Haven, 7 Dec 1906 (J.Wynne)

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

More about the long-tailed duck in Pembrokeshire