Herring
Gull - Zilvermeeuw (argentatus & argenteus)
(last update: 07 april 2004)
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Herring Gull CAAU adult (argenteus), November 01 2002, Westkapelle, the Netherlands (51.33N-03.25E).
A pale grey individual from the Belgian colour-ring program. Note the high primary moult score, with P9 already fully grown and P10 at the length of P8, PMS: 49. The orbital ring is yellow-orange, as is commonly found in western argenteus. A typical West-European argenteus, with obvious fine head streaking, an obvious sub-terminal band on P10 and the medial band on P10 covering an extensive range of the edge of the inner-web.
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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