The BTO winter atlas showed that Tufted Ducks were present in 10km squares with suitable fresh waters during the winters of 1981-82, 1982-82 and 1983-84.
The darker the colour, the higher the relative total count for each 10km square. The darkest blue represents 26-94 birds seen in a day.
Llys y fran, Pembroke, Bosherston and Bicton were the principal localities involved.
Graham Rees