Herring Gull- Zilvermeeuw (argentatus & argenteus)

(last update: 6-2-2007)

(2 images) Herring Gull 3cy H-127087, November 15 2003, Westkapelle, the Netherlands (51.33N 03.25E).

A bird with a Belgian ring: Bruxelles Belgium H-127087. Ringed as 2cy female on September 18 2002 at Oostende beach, Belgium (51.14N 02.53E). Not ringed as pullus, so not necessarily of local argenteus population, although general plumage development exact in line with average November 3cy argenteus, rather than argentatus. Primaries, secondaries and rectrices fully grown. Most of the greater and lesser coverts show an obvious brown hue and are worn at the fringes; the median coverts look fresher and are replaced again in the partial moult this autumn. They appear grey now.

From June to October, a complete moult will bring 3cy argenteus in so-called "third winter" plumage. By October, when the complete moult is finished, the head will show extensive 'winter streaking', mottled brown contrasting with the white breast as in an executioner's hood. The scapulars and mantle are pale adult-like grey.
By the end of the complete moult (October), all wing-coverts have been replaced, most to plain grey feathers. Immature patterns can often be found in the lower tertials, greater coverts and outer lesser coverts (the carpal edge).
During the summer, the primaries were moulted to third generation. The first inner primaries are dropped by late May and the outer primary P10 will be dropped by late August. The primary moult is completed by late-October in argenteus, when the new outer primary P10 is fully grown. The third generation primaries are clearly adult-like, with the inner primaries P1-P4 plain grey with a white tip. The outer-wing shows a clear black triangle, extending on the greater primary coverts. From P4 outwards, the primaries show a black sub-terminal band. The white primary tips are obvious in the inner primaries, but often smaller on P9 and P10. P10 has a small white mirror (lacking in some birds). The new tail-feathers will be white, with clear immature black markings. The iris is pale brown-yellow.