Herring
Gull - Zilvermeeuw (argentatus & argenteus)
(last update: 07 april 2004)
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Herring Gull BKAV 5cy (argenteus), August 01 2003, Zeebrugge, Belgium.
A bird with a blue Belgian ring: BKAV, from the Zeebrugge colony, ringed as pullus at Zeebrugge (51.21N 03.11E) on July 09 1999. P7-P10 are still old, and all secondaries and rectrices are still present. The red gonydeal spot is confined to the lower mandible and the bill has no black. The iris is white-yellow without speckling. The orbital ring is orange-yellow. The white tip merges with the mirror on P10. Direct comparison with partner suggests male (code M1).
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 August, the outermost primaries
P7-P10, are still present in argenteus in the Netherlands and northern
France. In most adults, the new primary P5 is just visible beneath the
tertials. At the same time, the outer median coverts,
outer lower lesser and innermost greater coverts have been renewed and contrast with the old, abraded adjacent wing-coverts.
The central median coverts are still missing. In summer, the head is still largely white,
but by the end of the summer, most adults develop extensive 'winter streaking', in
sub-adults strongly mottled
brown contrasting with the white breast as in an executioner's hood. The iris is
yellow in adults. The bill is yellow with a red
gonydeal spot confined to the lower mandible in the vast majority of
adults. The orbital ring is
yellow-orange or orange-red in argenteus. The legs are flesh-pink
in Dutch argenteus, although the odd individual shows slightly
yellowish legs.
| Remaining old primaries in adult (>4cy) Herring Gull in the Netherlands. | ||||||
| . | 17.08.00 | 21.08.01 | 22.08.01 | 23.08.00 | 28.08.00 | 30.08.00 |
| P10 | - | - | - | - | 1 | - |
| P9-P10 | - | - | - | 3 | 6 | 7 |
| P8-P10 | 8 | 7 | 17 | 47 | 29 | 33 |
| P7-P10 | 28 | 33 | 22 | 44 | 15 | 9 |
| P6-P10 | 10 | 10 | 7 | 12 | 2 | 2 |
| n: | 46 | 50 | 46 | 106 | 53 | 51 |
| m: | 4,0 | 4,1 | 3,8 | 3,6 | 3,2 | 3,1 |
| 95% CID: | 0,19 | 0,17 | 0,21 | 0,14 | 0,21 | 0,19 |
| SD: | 0,63 | 0,59 | 0,70 | 0,72 | 0,77 | 0,68 |
|
Notes: |
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