Here's a sample of mostly 2cy but also 3cy Herring Gulls in flight. All photographed in Köyliö landill, SW Finland 17th June 2014. I've numbered the different 2cy individuals such that there's a number above the series considering one and same individual.
32 2cy argentatus:
|Weird unpatterned and dark underwing coverts like in some GBBG.|
|Maybe some Caspian influence in this one with elegant structure and some pale grey lower scapulars.|
2cy Baltic Gull
|Complete set of 2nd gen primaries confirm the subspecies, heuglini shouldn't be this advanced yet.|
|This was the only 2cy with new, fully grown tertials (all of them!). Unfortunately I wasn't able to get flight shots.|
|Weird looking 2cy argentatus, no flight shots of this one either.|
A set of seven 3cy birds, different individuals marked similarly but with alphabets.
|Small mirror in P10|