Herring Gull (argentatus & argenteus)

(last update: February 11, 2013)

Herring Gull sub-adult, April 23 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. By April white-headed, sometimes still some streaking in northern argentatus but normally clean head in argenteus.

In this bird note black in tail and dark markings in secondaries, together with brown in coverts and no mirror on P10.