© P. Stewart

This adult or near-adult Yellow-legged Gull was trapped at Throckmorton Landfill as long ago as 1990. Note the relatively dark shade of grey of the upperwing, with a strongly contrasting white trailing edge. Pattern of primary tips with more extensive black than in argentatus Herring Gull and closer to argenteus. Black on six primaries, a white mirror on p10 but no mirror on p9, and a complete black band on p5. The evident head-streaking during December is unusual. Also, the dusky marks in the tail and wing-coverts may result from discolouring to a considerable extent but may indicate that this individual is a sub-adult.