Albert de Jong
Larus cachinnans? 2CY-3CY 13P3 November 28 2008 & March 13 2009, Deponie Pohlsche Heide - Minden, Germany (52°23'05N, 08°46'45E).
Green ring from Poland. Ringed as pullus green 13P3 & metal PLG DN-21244 on May 09 2007 in the mixed colony at Włocławek Reservoir, central Poland (52°39'N, 19°08'E). No details on parentage, and maybe "pure argentatus".
below: cachinnans? 2CY 13P3 November 28 2008, Deponie Pohlsche Heide - Minden, Germany (52°23'05N, 08°46'45E). Picture: Armin Deutsch.
Well streaked bird, with bold club-patterns on coverts and scapulars. Idealy cachinnans would now have a clean white head with a small beady eye, and much grey in the scapulars. Here, 13P3 has clearly replaced central MC and upper TT, and again these feathers show an anchor pattern; and it has no mirror on P10. These are strong clues for argentatus(~influences).
below: cachinnans? 3CY 13P3 March 13 2009, Deponie Pohlsche Heide - Minden, Germany (52°23'05N, 08°46'45E). Picture: Armin Deutsch.
The previous picture above: just look how argentatus-like this bird appears while preening, with a very rounded head.