Herring Gull - Zilvermeeuw (argentatus & argenteus): sub-adult Nov.
(last update: 07 april 2004)
Herring Gull sub-adult H-112037, November 15 2003, Westkapelle, the Netherlands (51.33N 03.25E).
A sub-adult with a Belgian ring H112037. Ringed as pullus on July 14 2000 at Zeebrugge, Belgium (51.20N 03.11E). The primaries are very adult-like, and the complete moult hasn't finished yet, P8 is fully grown, P9 is slightly shorter than P8. The tail is almost completely white but has limited black on the central tail-feathers.
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.