Herring
Gull - Zilvermeeuw (argentatus & argenteus)
(last update: 07 april 2004)
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Herring Gull H-130477 adult (argenteus), October 11 2003, Westkapelle, the Netherlands (51.33N-03.25E).
This adult is metal-ringed Bruxelles H-130477, ringed >4cy on June 22 2003 Zele Heikant, Belgium (51.04N 04.02E). The primary moult score: P8 fully grown, no old primaries left. Interestingly, this adult argenteus from Belgium, has no sign of any sub-terminal black on P5. This adult argenteus is missing the central greater coverts, so the secondaries underneath are exposed and appear fresh.
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 October, all the old primaries are shed in argenteus in the Netherlands and northern France. In adults, the new primaries are visible beneath the tertials. At the same time, the wing-covert moult is completed by the end of the month. 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.
