Herring
Gull - Zilvermeeuw (argentatus & argenteus)
(last update: 28 maart 2005)
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Herring Gull BYAT adult (argenteus), November 01 2004, Westkapelle, the Netherlands (51.33N 03.25E). Picture Pim Wolf.
An individual from the Belgian colour-ring program, probably ringed as adult at Zeebrugge (51.21N 03.11E) spring 2000 at the nest. The orbital ring is orange, as is commonly found in winter western argenteus. The primary moult score: P8 fully grown. The complete moult is almost finished. A typical West-European argenteus, with obvious fine head streaking but hardly any dark markings on the bill.
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.
|
Primary Moult Score of adult Herring Gull (argenteus & argentatus) at Scheveningen, the Netherlands in November, ranked by date. |
|||||
| date > | 03-11-00 | 11-11-00 | 14-11-01 | 20-11-00 | 28-11-00 |
| P6 | 1 | - | - | - | - |
| P7 | 10 | - | 5 | - | - |
| P8 | 71 | 37 | 70 | 31 | 20 |
| P9 | 23 | 38 | 80 | 60 | 60 |
| P10 | 3 | 12 | 22 | 36 | 156 |
| n (tot): | 108 | 87 | 177 | 127 | 236 |
| m (av): | 8,16 | 8,71 | 8,67 | 9,04 | 9,58 |
| 95% CID: | 0,13 | 0,15 | 0,11 | 0,13 | 0,08 |
| SD (s): | 0,66 | 0,70 | 0,73 | 0,73 | 0,64 |
|
n (tot): Total of
individuals by date. Total this month, n: 735. |
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