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 brown in coverts. Mirror on P9 and P10.