Herring Gull - Zilvermeeuw (argentatus & argenteus): sub-adult November
(last update: 07 april 2004)
Herring Gull sub-adult AYAR, November 16 2002, Westkapelle, the Netherlands (51.33N-03.25E).
A sub-adult from the Belgian colour-ring program, ringed blue AYAR. Note the relatively small white tips on the two outermost primaries and the brown-grey primary coverts. The primaries show well-defined small white tip in this individual, clearly demarcated from the black area. P5 has a broad square black sub-terminal marking confined to the outer-web. The division between grey and black is sharply defined, unlike the gradual dissolving black found in many northern Scandinavian argentatus.
From June to October, sub-adult Herring
Gull have a complete moult to so-called "winter plumage".
As long as the old outer third generation primaries are visible (until
August), ageing as 4cy is rather straightforward. From November onwards,
4cy birds much resemble adult birds, except that the bare parts still show
immature features: the black bill-band is obvious, extending over both
upper and lower mandible. On average, this plumage develops a more
pronounced winter 'hood' than in full adults: dense streaking on head,
especially around the eye and in the hind-neck. The upper-parts,
wing-coverts and tertials appear adult-like grey from 4cy October onwards.
The fourth generation tail-feathers are plain white.