Herring Gull- Zilvermeeuw (argentatus & argenteus)

(last update: 8-3-2007)

Herring Gull 3cy (argenteus), August 11 2003, Boulogne/Mer, France (50.42N - 01.34E).

With Dutch ring 5.x76.9xx. Primaries P9-P10 are still old second generation, while P7 is just slightly longer than P6 (in our field scores: P7 is fully grown, as it exceeds P6 in the folded wing). Note the obvious grey inner-webs on the inner primaries, visible below the tertials and the neat white tip on P6. Most of the median and lower lesser coverts, the inner greater coverts, some lesser coverts and the upper tertials have been replaced in the complete moult. The central greater coverts are missing, exposing the brown second generation secondaries underneath.

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. All wing-coverts will be 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 are 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.