Mergellus albellus – Lleian Wen – Scarce winter visitor. Not recorded from April to September
A cold weather visitor which occurs in Pembrokeshire when it is frozen out of its usual winter quarters further east. After such cold winter incursions, Smew occasionally reappear in the following winter, even if this latter season is mild. About 40 birds have been recorded in Pembrokeshire to date, since the first undated occurrences at Goodwick and Stackpole noted by Mathew (1894).
Most sightings have involved single birds but up to eight have been seen together. Smew have been recorded on fresh and salt water with about equal frequency, the Cleddau Estuary and Bosherston Pools being the most favoured localities. The redheaded female/immature predominates.