ddavid

Yes, Saunders's Gull changing from 1st-Winter plumage to 1st-Summer plumage. Structure & plumage are clearly indicative of this species.

Leg colour can be pretty variable in gulls & waders, and I think most experienced birdwatchers would generally use leg colour as a supporting (rather than a diagnostic) identification feature after first taking plumage & structural features into account.

david