With another Thayer's Gull lookalike recently in the UK (this time in North Lincolnshire), Steve Mlodinow has very kindly sent me a photograph of what he considers to be a typical juvenile.
Although the Lincolnshire juvenile 'looks the part', the size and structure of the bird, the size and length of the bill and the coarseness patterning of the plumage are more than worrying and perhaps suggest influence from elsewhere.
