Peter Adriaens (Belgium)
Ies Meulmeester (Netherlands)
Larus cachinnans 4CY KHDU February 11 2013, Lake of Constance - Altenrhein, Switzerland. Picture: Stephan Trösch.
Green KHDU, could it be XHDU from Germany?
Obvious mirror on P10. However, still black in tail, black on central tertials and lesser coverts and black band on bill.