Herring
Gull - Zilvermeeuw (argentatus & argenteus)
(last update: 01 april 2004)
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Herring Gull 55420 adult (argentatus), November 17 2003, Westkapelle, the Netherlands (51.33N 03.25E). Picture by Norman van Swelm.
An adult argentatus, ringed with Esonia ring: 55420. P5 has a small mark on the outer-web. A strong argentatus, probably a male, with the upper-parts hardly darker than local Dutch argenteus Herring Gulls. Baltic birds often show a yellow hue on the legs and seem to more often show a coral red orbital ring and a more powerful, stronger head and neck. The moult stage of the primaries is behind compared to local Dutch 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. Argentatus from Scandinavia are behind in
primary moult.
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, slightly darker, orange-red or
coral red in argentatus.
