Herring
Gull - Zilvermeeuw (argentatus & argenteus)
(last update: 21 februari 2004)
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Herring Gull BUAH adult (argenteus), May 03 2003, Voorhaven, Zeebrugge, Belgium (51.59N 04.02E).
An individual from the Belgian colour-ring program. Ringed as adult at Zeebrugge (51.21N 03.11E) on May 12 2000. The orbital ring is yellow-orange and the red gonydeal spot is confined to the lower mandible, as is commonly found in western argenteus.
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 late November, the average argenteus in the Netherlands and northern
France has completely moulted all primaries. 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.
