Albert de Jong
Larus cachinnans adult 7P72 August 06 2008, Łubna landfill, Poland. Picture: Ruud Altenburg.
Probably ringed as pullus May 2004 in central Poland, but data pending.
Flat head, long legs, parallel bill all classic for cachinnans. P10 pattern on underside of left wing seems to show a bit much black, but exact pattern hard to tell from this single picture.