Herring Gull (argentatus & argenteus)

(last update: February 11, 2013)

Herring Gull sub-adult, May 13 2014, Katwijk, the Netherlands.

Adult-like flight feathers. Older sub-adults (5CY) with last vestiges of immaturity in greater primary coverts (and sometimes dark marking on tail of coverts; often slightly more black on bill than in true adults). In 4CY birds combination of many such immature features, in combination with adult-like grey inner and central primaries showing clear-cut sub-terminal bands. In spring white-headed, sometimes still some streaking in northern argentatus but normally clean head in argenteus.

This 4CY bird didn't start the complete moult yet: P1 present in both wings, no mirror on P10.