Herring Gull - Zilvermeeuw (argentatus & argenteus)

(last update: 08 december 2003)

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Herring Gull S---adult (argenteus), September 26 2003, IJmuiden, the Netherlands (52.27N-04.33E).

A Dutch ringed adult: left black S, right black triple bars. A typical Dutch argenteus, with no black triangle on the outer-web of P5. P6 has an unbroken sub-terminal band and P10, which is heavily worn by September, has the tip merged with the mirror. P7 is already longer than P5. Note the fine head streaking and the on-going moult in the central greater coverts. This adult was ringed on the isle of Texel.

From June (often mid-May in France, Belgium and the Netherlands) to October, a complete moult will bring birds in so-called "adult winter" plumage. A new set of primaries will grow during the summer months and by September, the outermost primaries P9-P10 are still present in argenteus in the Netherlands and northern France. In most adults, the new primary P6 is just visible beneath the tertials and shows a clear sub-terminal band. At the same time, the median coverts, outer lower lesser and outer greater coverts have been renewed and strongly contrast with the old, abraded adjacent wing-coverts. In summer, the head is still largely white, but by September, most adults develop extensive 'winter streaking', in sub-adults strongly mottled brown contrasting with the white breast as in an executioner's hood. The scapular coverts are plain grey, lacking white crescents. The tertials show obvious white tips. The iris is yellow. The bill is yellow with a red gonydeal spot confined to the lower mandible. The orbital ring is yellow-orange in most argenteus.