Peter Adriaens (Belgium)
Ies Meulmeester (Netherlands)
Larus cachinnans 1CY XCDP September 07 2012, Guernsey, Great Britain. Picture: Paul Veron.
Green XCDP, ringed on May 30 2012 as pullus "Silbermöwe - Art unbest. (Larus argentatus/cachinnans/michahellis)" at Oberspreewald-Lausitz, Brandenburg, Germany (51°42'00"N 014°06'00"E). This is 100 km SE of Berlin.
Bird from a mixed colony; there seem to be at least 'a few' indications for cachinnans influence: moult stage, jizz, tertial pattern, vent.