Anas penelope – CHWIWELL – Winter visitor and passage migrant
Past evidence suggests that the wigeon may well have been more numerous than it is now. At the Orielton Decoy 500-600 were taken annually during the winters of the 1870s and 1880s, suggesting that a very large population must have been present. Mackworth Praed (1946) thought that probably 9,000-10,000 was the daily presence at Orielton prior to the 1930s, but in that decade numbers dwindled to about 3000 on the nearby estuary. Lloyd noted about 3000 at Angle Bay in 1925. A continued slow decline seems indicated by records of 2500 in the Hook area in 1949 and 1950, and about 2200 in Angle Bay in 1974. The average of the peak counts for the whole of the Cleddau Estuary from 1983 to 1986 was 2060, and from 1988 to 1992 was 2331.
The picture changes when severe cold weather grips wintering areas further east, as it did in January 1987. Suddenly about 10,000 wigeon appeared on or near the Cleddau Estuary with a further 3000 elsewhere, demonstrating how important the preservation of estuarine habitat in the mild west is.
Away from the Cleddau the wigeon is normally concentrated only at Marloes Mere (100-500 birds) and the Pentood Marshes (200-500 birds), with smaller groups using ponds and farm irrigation reservoirs. These inland waters also provide a refuge during cold spells, as in 1987 when there were 1,000 at Treleddin Farm reservoir, 860 at Llysyfran reservoir, about 500 at Maerdy and about 500 at Bosherston Pools.
Wigeon arrive in Pembrokeshire from September to December. Numbers peak in January, with a rapid departure in late March and stragglers occurring thereafter. Small parties are seen passing Strumble Head and stopping off at the offshore islands during the arrival period but the bulk arrive unseen, presumably during the night. Little visible movement is seen during the rapid spring departures.
Recoveries of Wigeon ringed at Orielton from 1937 to 1961 show that many of our winter birds breed on the western Siberian Plain, as far as 65 degrees east. The recovery pattern also shows that they move down through the Baltic region after breeding, and that some of the birds that stop off in Pembrokeshire later carry on to Ireland. Some return in subsequent winters but other range widely in France, Portugal, Spain and Italy.
PRAED, C.W. MACKWORTH. 1946. Orielton decoy ringing station report. London, The International Committee for Bird Preservation.