Herring Gull (argentatus & argenteus)

(last update: February 11, 2013)

Herring Gull sub-adult, July 18 2013, Noordwijk, the Netherlands.

Clean white head and adult-looking bare parts (especially bill) maybe best match mature birds, not 3CY. Note also pattern on inner secondaries.
However, P7 has no sign of a sub-terminal band (but it has to be said its best to check this feature on P5-P6), no mirror on P10, very extensive brown on outer secondaries leaving just a thin white fringe at the tip and much black in tail are all good indications for 3Cy. Probably best left labeled "sub-adult".

Complete moult: P4/P7.