Herring Gull- Zilvermeeuw (argentatus & argenteus)

(last update: 6-2-2007)

(2 images) Herring Gull 3cy H-107901 (argenteus), October 18 2002, Westkapelle, the Netherlands (51.33N-03.25E).

A bird with a Belgian ring: Bruxelles Belgium H-107901, ringed as pullus on July 06 2000 at Zeebrugge (51.20N 03.11E). Primaries P1-P8 are fully grown. Most of the wing-coverts show an obvious brown hue and are worn at the fringes.

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.

(image above) H-107901 (argenteus), October 18 2002, Westkapelle, the Netherlands (51.33N-03.25E).

(image below) H-107901 (argenteus), November 16 2002, Westkapelle, the Netherlands (51.33N-03.25E).

Another image of H-107901, one month later. Still extensive patterning on tertials and wing-coverts. The small tips on the outer primaries, black in the tail, diffuse brown hue on upper-parts and the typical immature coloration of the bill point to 3cy.