Great Black-backed Gull - 1980s winter atlas

The BTO winter atlas showed that Great Black-backed Gulls were present in most 10km squares 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 over 60 birds, being concentrated in squares SM 80 & 81.

Graham Rees