Breeding resident
The first record for this species was of four at Skokholm on 3 October 1952. Their origin is unclear, since Canada Geese were not introduced until 1955 at Boulston and 1957 at Orielton. They continued to breed at Orielton until 1977 but have apparently not done so since. The Boulston group has become well established and has built up from 30 in 1968 to 78 by 1971 and 159 by 1986. Although single pairs bred at Haroldston West and Sheep Island in 1976 . the population otherwise remained confined to the upper Cleddau Estuary. They began to spread in 1984 and by 1988 their breeding distribution was as shown on the map. Breeding productivity has been low with up to ten fledglings being recruited per year.
Canada Geese return to the upper Cleddau to moult and are seldom recorded away from that area in the winter. The occasional records from the Pentood area, the Gwaun, Llysyfran reservoir and Maenclochog are thought to be attributable to wanderers from the group that is resident at Newcastle Emlyn, Ceredigion, while a flock of about 70 seen at several localities between Dinas and Strumble Head in September 1989 occurred at a time when Canada Geese were absent from Newcastle Emlyn.
Fieldwork 1984-88 (based on 478 tetrads)
Red = breeding confirmed = 6
Orange = breeding probable = 5
Yellow = breeding possible = 5
Total tetrads in which registered = 16 (3.4%)