Larus ridibundus ridibundus – GWYLAN PENDDU – Winter visitor and passage migrant, formerly bred.
There was said to be a large colony on Caldey in 1662, the only one on record until 1947, when three or four pairs were present in the St Davids area, and were believed to have bred, but if so, the eggs were taken by local countrymen. In 1948 J.F. found breeding, six pairs of Dowrog and four pairs at Trefeiddan, and photographed nests with eggs and young. A common winter visitor from July to April, and some birds are seen in May and June.