Albert de Jong
Larus cachinnans PLG DN-04725 1CY, November 24 2017, Katwijk, the Netherlands.
Ringed as pullus on May 22 2016 at Rz.Wisła, Włocławek:tama - Poland (52°39'32.0''N 19°8'4.4''E). This is a mixed colony of argentatus and cachinnans. On these pictures there is a strong cachinnans feeling.
All scaps except rear lower scaps still juvenile. Lefty side probably single lesser covbert replaced for 2nd gen too.