Herring Gull- Zilvermeeuw (L. argentatus argentatus)(last update: 04 december 2003) |
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Herring Gull argentatus |
The
taxon argentatus is an abundant breeding species in NE Europe, from
Denmark, the coast of the Baltic Sea, Scandinavia and coast of the White
Sea. In the south-east of the breeding range (Denmark and the NW German coast),
birds gradually start to show characteristics of taxon argenteus,
indicating there is a cline in the argenteus-argentatus
taxa: argenteus in Western Europe is pale-backed, slightly smaller
and with relatively much black in the wing-tip; argentatus in the
NE Europe is larger, slightly darker on upper-parts and show less black in
the wing-tip. The description of argentatus below
largely follows P.J. Grant: "Gulls, a guide to
identification" and E.K Barth's publication as Contribution No. 86,
Zoological Museum, University of Oslo: "The circumpolar systematics
of Larus argentatus and Larus fuscus with special reference
to the Norwegian populations". Due to the large breeding range, there is much intra-specific variation in argentatus, with most powerful birds in the northern populations, showing the most darkest upper-parts, longest wing and most white in the outer-wing. Some populations may hold substantial number of yellow-legged argentatus. (referred to as "Finnmark yellow-legged argentatus"). In adult plumage, the black sub-terminal spot on P5 is often lacking or strongly reduced to a diffuse streak, broken at the centre. Sometimes P6 lacks black as well. In the Baltic region, other yellow-legged argentatus populations occur ("Baltic yellow-legged argentatus"), with adults showing even brighter yellow legs in summer and the upper-parts only slightly darker than West European argenteus, still much paler than Yellow-legged Gull (michahellis). Those paler mantled argentatus often show a limited black sub-terminal spot on P5 in adult plumage. 1CY
ARGENTATUS
The partial autumn moult (moult into so-called "first winter" plumage) includes the body and head feathers. This moult starts as soon as the nest is abandoned (late June) and continues until January. In general, the head turns paler on throat and forehead. The breast turns paler as well. The feathers on belly and vent are still juvenile in most 1cy argenteus by November. The mantle and upper scapulars are moulted to second generation feathers, showing an anchor pattern and a dark base. The lowest row of scapulars are still juvenile by March in most 2cy birds (contra e.g. michahellis). The juvenile wing-coverts, rectrices and remiges start to bleach and show wear in the fringes.
2CY ARGENTATUS
From May onwards, a complete
moult will bring birds in so-called "second
winter" plumage by October. The head will show neat fine
streaking by October; the under-parts and rump turns pale, mottled brown. The scapulars and mantle
moult to third generation feathers, especially in the mantle and upper
scapulars. The pattern is more or less similar to the anchor pattern of
the second generation feathers, but can be recognized by the warm buffish
tone and neat white fringe as long as the feathers are fresh. Only a few new scapulars
may be
pale grey adult-like feathers. By October, the upper scapulars are
replaced and argenteus is actively moulting the lower scapulars, with still some
old second generation rear lower scapulars.
According to Grant ("Gulls, a guide to identification"), the next moult in argenteus is a partial moult in spring (in 3cy birds). However, continental argenteus has a partial moult in autumn in second calendar year as well (click here for a clear example). The moult sequence in autumn in the scapulars is not completely clear, but from September onwards, 2cy argenteus may moult the upper tertials, innermost greater coverts and various amount of median coverts and sometimes lower lesser coverts to third generation feathers (some of them more adult-like in pattern). This moult to third generation wing-coverts may overlap with the replacement to second generation feathers (the last replaced coverts: upper lesser coverts and the seventh and eighth greater coverts).
3CY ARGENTATUS
From June to October, a complete
moult will bring birds in so-called "third winter" plumage.
In summer, the head is still largely grey, but after the complete moult is
finished, the head shows extensive 'winter streaking', mottled brown contrasting with the white
breast as in an
executioner's hood. The
scapulars and mantle are pale adult-like grey, although some lower
scapulars may show a pale brown hue.
4CY ARGENTATUS
From June to October, a complete
moult will bring birds in so-called "adult winter" plumage.
As long as the old outer third generation primaries are visible (until
August), ageing as 4cy argenteus is rather straightforward. From
November onwards, 4cy argenteus much resembles adult birds, except
that the bare parts still show immature feathers: the black bill-band
is obvious, extending over both upper and lower mandible. On average, this
plumage develops a more pronounced winter 'hood' than in full adults: dense streaking on head,
especially around the eye and in the hind-neck. The upper-parts,
wing-coverts and tertials appear adult-like grey from 4cy October onwards.
The fourth generation tail-feathers are plain white.
ADULT ARGENTATUS
Measurements in mm’s wing: 375-447, tail: 152-189, bill: 45-58, tarsus: 55-70; n = 18 (origin of taxon unknown, Dwight, 1925). |
ARGENTATUS & ARGENTEUS Herring Gulls are treated together. Click the thumbnails to go the monthly sections. |
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August
1cy. (argenteus), August 18 2001, Maasvlakte, the Netherlands (51.58N-04.02E). |
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September 1cy. A1FV (argenteus), September 22 2002, Boulogne/Mer, NW France (50.43N-01.37E). |
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October
1cy. H-12?4 (argenteus), October 05 2002, Boulogne/Mer, France (50.43N-01.37E). |
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November 1cy. HNJ (argenteus), November 07 1999, Westkapelle, the Netherlands (51.33N-03.25E). |
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December
1cy. VXV8 (argentatus), December 23 2002, Amsterdam, the Netherlands (52.21N-04.52E). |
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January
2cy. H-117045 (argenteus), January 04 2002, Boulogne/Mer, France (50.42N,1.34E). |
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February 2cy. BZAM (argenteus), February 15 2001, Oostende, Belgium (51.13N-02.55E). |
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March
2cy. VA33 (argentatus), Denmark and Finland. Pictures from Denmark by Frank Abrahamson. |
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April 2cy. 5.365.836 (argenteus), April 19 2002, Boulogne/Mer, France (50.42N,1.34E). |
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May 2cy. H-117661 (argenteus), May 16 2002, Boulogne/Mer, France (50.42N,1.34E). |
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June
2cy. DA 216321 (argenteus), June 13 2002, Boulogne/Mer, France (50.42N,1.34E). |
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July
2cy. DA 212950 (argenteus), July 10 & 11 2002, Boulogne/Mer, France (50.42N,1.34E). |
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August
2cy. C527R (argentatus), August 11 2002, Tampere, Finland (61.31N,23.43E). |
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September 2cy. 5.358.143 (argenteus), September 24 2002, IJmuiden, the Netherlands (52.27N-04.33E). |
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October 2cy. H-113894 (argenteus), October 03-04 2002, Boulogne-sur-Mer, France (50.43N-01.37E). |
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November 2cy. 5.365.084 (argenteus), November 16 2002, Westkapelle, the Netherlands (51.33N-03.25E). |
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December
2cy. (argenteus), December 21 2001, Brouwersdam, the Netherlands (51.45N-03.51E). |
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January 3cy. H-108929 (argenteus), January 05 2002, Boulogne/Mer, France (50.42N,1.34E). |
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February 3cy. (argenteus), February 07 2002, IJmuiden, the Netherlands (52.27N-04.33E). |
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April
3cy. (argenteus), April 12 2001, IJmuiden, the Netherlands (52.27N-04.33E). |
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May
3cy. KCU (argenteus), May 23 2002, Maasvlakte, the Netherlands (51.59N,04.02E). |
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June 3cy. H-105381 (argenteus), June 13 2002, Boulogne/Mer, France (50.42N,1.34E). |
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July
3cy. H-xxxxxx (argenteus), July 11 2002, Boulogne/Mer, France (50.42N,1.34E). |
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August
3cy. C525K (argentatus), August 11 2002, Tampere, Finland (61.31N,23.43E). |
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September 3cy. 5.335.124 (argenteus), September 24 2002, Scheveningen, the Netherlands. |
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October
3cy. H-107901 (argenteus), October 18 2002, Westkapelle, the Netherlands (51.33N-03.25E). |
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November
3cy. H-107901 (argenteus), November 16 2002, Westkapelle, the Netherlands (51.33N-03.25E). |
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December
3cy. (argentatus), December 21 2001, Brouwersdam, the Netherlands (51.457N-03.51E). |
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January
sub-adult. HT-195.171 (argentatus), January 04 2002, Boulogne/Mer, France (50.42N,1.34E). |
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February
sub-adult. 5.325.398 (argenteus), February 04 2002, IJmuiden, the Netherlands (52.27N-04.33E). |
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April
sub-adult. (argentatus), April 19 2002, Boulogne/Mer, France (50.42N,1.34E). |
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May
sub-adult. (argenteus), May 31 2002, Maasvlakte, the Netherlands (51.59N,04.02E). |
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August
sub-adult. C154A (argentatus), August 12 2002, Tampere, Finland (61.31N,23.43E). |
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October
sub-adult. 5.325.398 (argenteus), October 22 2002, IJmuiden, the Netherlands (52.27N-04.33E). |
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November
sub-adult. BHAK (argenteus), November 16 2002, Westkapelle, the Netherlands (51.33N-03.25E). |
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January
adult. X994 (argentatus), January 04 2002, Boulogne/Mer, France (50.43N-01.37E). |
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February adult. 5.360.719 (argenteus), February 04 2002, IJmuiden, the Netherlands (52.27N-04.33E). |
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March adult. 5.359.457 (argenteus), March 18 2002, Maasvlakte, the Netherlands (51.59N,04.02E). |
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April adult. 5.536.103 (argenteus), April 15 2001, IJmuiden, the Netherlands (52.27N-04.33E). |
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May
adult. (argenteus), May 13 2002, Dintelhaven, Maasvlakte, the Netherlands (51.59N,04.02E). |
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June adult. (argenteus), June 26 2001, Bergen op Zoom, the Netherlands (51.29N-04.17E). |
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July
adult. (argenteus), July 14 2001, IJmuiden, the Netherlands (52.27N-04.33E). |
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August
adult. CR47 (argentatus), August 08 2002, Tampere, Finland (61.31N,23.43E). |
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September adult. SA (argenteus), September 24 2002, IJmuiden, the Netherlands (52.27N-04.33E). |
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October adult. JR9 (argenteus), October 19 2002, Brouwersdam, the Netherlands (51.457N-03.51E). |
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November adult. H-125585 (argenteus), November 16 2002, Westkapelle, the Netherlands (51.33N-03.25E). |
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December
adult. (argentatus), December 21 2001, Brouwersdam, the Netherlands (51.457N-03.51E). |