Albert de Jong
Larus cachinnans 3cy, November 10 2008, Westkapelle, the Netherlands. Picture: Ies Meulmeester.
Note the heavy and bulky build and the relatively pale whitish iris in this 3cy Caspian Gull. The following features are good points to allow identification of this plumage as being 3cy: the pinkish colored bill with a black subterminal band on the gonys, the indistinct and unsharp cutting edges of the black on the primaries, the immature brown/blackish patterns and markings in the wing-coverts and tertials, small white primary tips, some dark markings in the tail, a large and broad mirror on P10 (but admittedly with a solid black subterminal band between the mirror and the white primary tip) and also a rounded mirror on P9.