Herring Gull- Zilvermeeuw (argentatus & argenteus)

(last update: December 15, 2011 )

Herring Gull - 1cy October

Introduction

This website deals with the Herring Gulls of the taxa argentatus and argenteus. Argenteus is an abundant breeding species on Iceland, Britain, NW France, Belgium, the Netherlands and N Germany. The taxon argentatus breeds in NE Europe, from Denmark, the coast of the Baltic Sea, Scandinavia and coast of the White Sea. In the centre of the breeding range (Denmark and the NW German coast), birds show intermediate characteristics, indicating there is a cline in argenteus-argentatus. 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.
Due to the large breeding range, there is much intra-specific variation in argentatus, with most large, powerful birds in the northern populations, showing the most darkest upper-parts, longest wing and most white in the outer-wing. In this region, 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 Baltic argentatus often show a black sub-terminal spot on P5 in adult plumage.
On these web-pages, we largely follow 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".

1cy Herring Gull: description for October

By October, NW European Herring Gull is not in fresh juvenile plumage anymore. But birds hatched in northern Russia still show a complete juvenile plumage, with the head and under-parts streaked grey-brown, rather pale on forehead and throat and with dark ear-coverts. The mantle and scapulars in these juveniles are brown based with buffish-yellowish fringes when the feathers are fresh. The notched pattern is repeated on the lesser, lower lesser and median coverts, although the medians often have paler centres. The greater coverts show a 'piano-key' pattern. On average, the tertials have an obvious notched pale fringe and transversal bar. This is more pronounced in argenteus than in argentatus. The secondaries, primaries and primary coverts are dark with a small white tip, but the inner primaries show an obvious, sometimes translucent, pale window, prominent from below and above. The under-wing is rather uniform grey-brown patterned. The tail has a broad sub-terminal band and isolated dark bars on the basal half. Some argentatus show a broken tail-band, reminiscent to Great Black-backed Gull (L. marinus). The iris is very dark, the bill is blackish, sometimes with a paler base, and the legs are flesh-pink with dark shins.

1cy Herring Gull: post-juvenile moult

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 (especially in southern populations) and continues until January. Early argenteus juveniles fledge by late-June in the Netherlands, argentatus fledge mid-July in northern USSR. The post-juvenile moult is most extensive in southern Herring Gull populations and very obvious in October. Northern juvenile argentatus may postponed the post-juvenile moult until February, hence retain a juvenile plumage (e.g. this Russian 2cy argentatus in February).
In the post-juvenile moult, the head turns paler on throat and forehead. The breast turns paler as well, but most is an effect of bleaching and wear. The feathers on belly and vent remain juvenile in most 1cy argenteus by November. 
1cy October birds in NW Europe have the mantle and upper scapulars moulted to second generation feathers, showing an anchor pattern and a dark base. This moult normally starts in the rear upper scapular region high on the back, and progresses downwards to the lower scapulars. The rear lower scapulars, which are the longest scapulars, lying on the scapular coverts, are normally still juvenile by February. By October, many birds have almost all upper scapulars replaced (over 75% second generation, i.e. category A-B in our research). When the feathers are fresh, they may show warm ginger tones, but after a few weeks these warm tones bleach paler, to white later in the season. 
In 2cy argenteus in NW France (from Belgian, Dutch and British populations), the lowest row of scapulars are still juvenile by 2cy March in the vast majority of birds (contra e.g. the southern taxon michahellis). Both argenteus and argentatus normally exclude all tertials and wing-coverts from the post-juvenile moult. However, we estimate 2-4% of argenteus to include one or a few wing-coverts or a single tertial in the post-juvenile moult (often in a later stage of this moult, when scapular moult is well underway). We don't have sufficient data to estimate for argentatus, but several pictures show this phenomenon in argentatus as well. The juvenile wing-coverts, rectrices and remiges start to bleach and show wear in the fringes from 1cy September onwards.

Most 1cy argenteus and argentatus from S-Scandinavia show post-juvenile moult by October. We do not get high northern birds early in autumn, but ringed bird in November - March show that these individuals may remain completely juvenile for a much longer period. Below, we included a table of 16 ringed argenteus, of which only 1 did not start the post-juvenile moult (but this bird was scored on 01 October). 
From a "definition point of view", we score this birds category F (0% 2g feathers) as the second generation feathers are still not visible. Only when these new feathers are visible, birds move to category E (1-24% 2g), as it is very hard to interpret missing minute upper scapulars in the upper region. On the other far end we have category A (100% 2g feathers) which is only used when the longest rear lower scapulars are dropped as well. These longest scapulars are the last to be moulted in the entire scapular region. Some birds already moult to third generation scapulars in the upper region, while these longest lower scapulars are still juvenile.
By early October, most advanced birds (like this Belgian bird) have almost all upper scapulars new and over 50% of the lower scapulars replaced. We also include tables of unringed birds from late October. many birds have all the upper scapulars moulted and only the longest rear lower scapulars are still juvenile. Several birds have some wing-coverts/tertials moulted.

1cy Herring Gull October: tables and charts

Oct-Table 1: post-juvenile moult score in ringed L. argentatus argenteus in 2001, 2002 and 2003. 

CODE DATE SIDE RING TT & COVS 2g   TOTAL
        # US LS SCAPS
BLB 1-okt L H-117774 0 F F F
BLB 5-okt L H-12XXX4 0 B C B
BLB 5-okt nn H-124880 0 D E D
BLB 5-okt nn H-124736 0 E F E
NLA 5-okt nn 5.412.XXX 0 B E D
NLA 5-okt nn 5.412.514 0 B E D
NLA 11-okt R 5.286.728 0 B D C
NLA 11-okt L 5.286.728 0 B D C
BLB 17-okt nn H-124249 0 B E D
NLA 17-okt R 5.364.886 0 C D C
NLA 23-okt L 5.412.502 0 E F E
NLA 23-okt R 5.412.502 0 E F E
BLB 24-okt nn H-1242XX 0 A E C
BLB 24-okt nn H-124149 0 B F D
NLA 24-okt nn 5.410.127 0 B E C
NLA 25-okt R 5.412.512 0 B E C

Code BLB: ringed in Belgium; NLA: ringed in the Netherlands.
Side L: left; R: right; nn: not noted.
TT & COVS: moult score in tertials and wing-coverts.
2g US: second generation upper scapulars; LS: lower scapulars.
TOTAL SCAPS: % of second generation scapulars.
Classification: A: 100% 2g; B: 75-99% 2g; C: 50-74% 2g; D: 25-49% 2g; E: 1-24% 2g; F: 0% 2g. 

 

Oct-Chart 1 (below): 1cy HG coverts & scapulars scores 05-10-2002, at Dannes (gravel pit), NW France (n = 40). 2nd generation wing coverts: n=2 (2 & 2 feathers moulted). For classification and codes, see table above.

Oct-Chart 2 (below): 1cy HG coverts & scapulars scores 22-10-2002, at IJmuiden (Zuidpier), Netherlands (n = 20). 2nd generation wing coverts: n=3 (1, 1 & 3 feathers moulted).

Oct-Chart 3 (below): 1cy HG coverts & scapulars scores 24-10-2002, at Boulogne/Mer (roof resting flock), NW France (n = 51). 2nd generation wing coverts: 0

rings argenteus: U.K.

2cy argenteus in March, ringed in France. (57822 bytes)Herring Gull A6LS, 1cy (argenteus), October 31 2009, Boulogne/Mer, France (50.42N,1.34E). Picture: J-M Sauvage.
rings argenteus: France
2cy argenteus in March, ringed in France. (57822 bytes)Herring Gull 87A, 1cy (argenteus), October 22 2007, Westkapelle, the Netherlands.
2cy argenteus in March, ringed in France. (57822 bytes)Herring Gull FSA, 1cy (argenteus), October 24 2008, Westkapelle, the Netherlands.
2cy argenteus in March, ringed in France. (57822 bytes)Herring Gull J3A, 1cy (argenteus), October 28 2007, Boulogne/Mer, France (50.42N,1.34E). Picture: J-M Sauvage.
rings argenteus: Belgium
1cy argenteus in November, ringed in Belgium. (25637 bytes)Herring Gull FBAD 1cy (argenteus), October 15 2006, Oostende, Belgium. Picture W. Leers.
1cy argenteus in November, ringed in Belgium. (25637 bytes) Herring Gull FCAV 1cy (argenteus), October 27 2006, Westkapelle, the Netherlands.
1cy argenteus in November, ringed in Belgium. (25637 bytes)Herring Gull FMAT 1cy (argenteus), October 27 2006, Westkapelle, the Netherlands.
1cy argenteus in November, ringed in Belgium. (25637 bytes)Herring Gull GDAM 1cy (argenteus), October 26 2007, Westkapelle, the Netherlands (51.33N - 03.25E).
1cy argenteus in November, ringed in Belgium. (25637 bytes)Herring Gull GDAR 1cy (argenteus), October 26 2007, Westkapelle, the Netherlands (51.33N - 03.25E).
1cy argenteus in October, ringed in Belgium. (84806 bytes)Herring Gull H-117774 1cy (argenteus), October 01 2001, Boulogne/Mer, France (50.43N - 01.37E).
1cy argenteus in October, ringed in Belgium. (71047 bytes)Herring Gull H-12???4 1cy (argenteus), October 05 2002, Boulogne/Mer, France (50.43N-01.37E).
1cy argenteus in October, ringed in Belgium. (86247 bytes)Herring Gull H-131548 1cy (argenteus), October 27 2004, Westkapelle, the Netherlands (51.33N - 03.25E). Picture by Pim Wolf.
1cy argenteus in October, ringed in Belgium. (128336 bytes)Herring Gull H-xx8622 1cy (argenteus), October 21 2004, Westkapelle, the Netherlands (51.33N 03.25E). Picture Pim Wolf.
rings argenteus: the Netherlands
1cy argenteus in November, ringed in Belgium. (25637 bytes)Herring Gull D.8 1cy (argenteus), October 22 2012, Hoek van Holland, the Netherlands.
2cy argenteus in March, ringed in France. (57822 bytes)Herring Gull (argenteus) P.G 1CY-2CY, October 2012 - February 2013, Hoek van Holland, the Netherlands. Picture: Wim van Yperen.
1cy argenteus in August, ringed in Belgium. (90559 bytes)Herring Gull KABZ 1cy (argenteus), October 12 2010, Leiden, the Netherlands.
1cy argenteus in August, ringed in Belgium. (90559 bytes)Herring Gull KACH 1cy (argenteus), October 11 & November 04 2010, Westkapelle, the Netherlands.
1cy argenteus in August, ringed in Belgium. (90559 bytes)Herring Gull KVAK 1cy (argenteus), October 09 2009, IJmuiden, the Netherlands.
1cy argenteus in October, ringed in the Netherlands. (71198 bytes)Herring Gull 5.286.728 1cy (argenteus), October 11 2003, Brouwersdam, the Netherlands.
1cy argenteus in October, ringed in the Netherlands. (57050 bytes)Herring Gull 5.364.886 1cy (argenteus), October 11-17 2002, IJmuiden, the Netherlands (52.27N - 04.33E).
adult argenteus in October, ringed in the Netherlands. (79042 bytes)Herring Gull 5.412.38x 1cy (argenteus), October 18 2009, IJmuiden, the Netherlands.
1cy argenteus in October, ringed in the Netherlands. (85426 bytes)Herring Gull 5.412.502 1cy (argenteus), October 23 2003, IJmuiden, the Netherlands (52.27N - 04.33E).
1cy argenteus in October, ringed in the Netherlands. (70314 bytes)Herring Gull 5.412.512 1cy (argenteus), October 25 2003, Amsterdam, the Netherlands.
1cy argenteus in August, ringed in Belgium. (90559 bytes)Herring Gull 5.429.0xx 1cy (argenteus), October 14 2010, Westkapelle, the Netherlands.
1cy argenteus in December, ringed in the Netherlands. (119951 bytes)Herring 5.429.2871cy (argenteus), 2010-2011, IJmuiden, the Netherlands.
adult argenteus in October, ringed in the Netherlands. (79042 bytes)HerringGull 6.166.610 1cy (argenteus), October 26 2011, Leiden, the Netherlands.
adult argenteus in October, ringed in the Netherlands. (79042 bytes)HerringGull 6.168.269 1cy (argenteus), October 30 2011, IJmuiden, the Netherlands. Also as 4cy.
rings argentatus: Helgoland / Germany
1cy argenteus in October, ringed in Belgium. (128336 bytes)Herring Gull H4.6N 1cy (argentatus), October 26 2007, Amsterdam, the Netherlands.
rings argentatus: Norway
1cy argentatus in August. (62968 bytes)Herring Gull (argentatus) J2400 1CY, October 13 2011, Bergen, Norway. Picture: Christian Pedersen.
rings argentatus: Sweden
1cy argentatus in August. (62968 bytes)Herring Gull 1cy (argentatus), Simrishamn, Sweden, October 06 2009. Picture: Hans Larsson. Ringed in Sweden.
rings argentatus: Finland
Herring Gull 1cy (argentatus) C2X5 October 2005, Tampere, Finland (61.31N,23.43E). Picture Hannu Koskinen.
Herring Gull 1cy (argentatus) C4X6 October 2005, Tampere, Finland (61.31N,23.43E). Picture Hannu Koskinen.
Herring Gull 1cy (argentatus) C4X9 October 2005, Tampere, Finland (61.31N,23.43E). Picture Hannu Koskinen.
Herring Gull 1cy (argentatus) C5Y8 October 2005, Tampere, Finland (61.31N,23.43E). Picture Hannu Koskinen.
Herring Gull 1cy (argentatus) C5Y9 October 2005, Tampere, Finland (61.31N,23.43E). Picture Hannu Koskinen.
Herring Gull 1cy (argentatus) C5Z4 October 2005, Tampere, Finland (61.31N,23.43E). Picture Hannu Koskinen.
Herring Gull 1cy (argentatus) C6X6 October 2005, Tampere, Finland (61.31N,23.43E). Picture Hannu Koskinen.
Herring Gull 1cy (argentatus) C7X9 October 2005, Tampere, Finland (61.31N,23.43E). Picture Hannu Koskinen.
Herring Gull 1cy (argentatus) C7Y2 October 2005, Tampere, Finland (61.31N,23.43E). Picture Hannu Koskinen.
Herring Gull 1cy (argentatus) C8Y0 October 2005, Tampere, Finland (61.31N,23.43E). Picture Hannu Koskinen.
Herring Gull 1cy (argentatus) C9X1 October 2005, Tampere, Finland (61.31N,23.43E). Picture Hannu Koskinen.
rings argentatus: Russia
1cy argentatus in August. (62968 bytes)Herring Gull (argentatus) KF87 1CY, October 31 2011, Bergen, Norway. Picture: Christian Pedersen.
juvenile LBBG in October, ringed in Norway. (131273 bytes)Herring Gull KY14 1cy (argentatus), October 19 2007, Hoek van Holland pier (51.59 N, 4.06E), the Netherlands. Picture: Evert Eijkelenboom.
Herring Gull 1cy (argentatus) KJN6J October 2005, Tampere, Finland (61.31N,23.43E). Picture Hannu Koskinen. Bird ringed in the S White Sea, N Russia.
1cy argenteus in November, ringed in Belgium. (25637 bytes)Herring Gull RUM ES14266 1cy (argentatus), October 22 2012, Scheveningen, the Netherlands.
unringed 1cy Herring Gulls
1cy argentatus in August. (62968 bytes)Herring Gull 1cy (argentatus), Simrishamn, Sweden, October 06 2009. Picture: Hans Larsson.
2cy argenteus in March, ringed in France. (57822 bytes)Herring Gull 1CY, October 20 2014, Katwijk, the Netherlands.
2cy argenteus in March, ringed in France. (57822 bytes)Herring Gull 1CY, October 20 2014, Katwijk, the Netherlands.
2cy argenteus in March, ringed in France. (57822 bytes)Herring Gull 1CY, October 20 2014, Katwijk, the Netherlands.
2cy argenteus in March, ringed in France. (57822 bytes)Herring Gull 1CY, October 20 2014, Katwijk, the Netherlands.
2cy argenteus in March, ringed in France. (57822 bytes)Herring Gull 1CY, October 20 2014, Katwijk, the Netherlands.
2cy argenteus in March, ringed in France. (57822 bytes)Herring Gull 1CY, October 20 2014, Katwijk, the Netherlands.
2cy argenteus in March, ringed in France. (57822 bytes)Herring Gull 1CY, October 20 2014, Katwijk, the Netherlands.
1cy argenteus in October. (74059 bytes)Herring Gull 1cy, October 05 2002, Boulogne/Mer, France (50.43N-01.37E).
One lower lesser covert moulted.
1cy Herring Gull in October. (87124 bytes)Herring Gull 1cy (argenteus), October 11 2011, Scheveningen, the Netherlands.
1cy Herring Gull in October. (87124 bytes)Herring Gull 1cy (argentatus), October 21 2001, Westkapelle, the Netherlands (51.33N - 03.25E). Picture by Pim Wolf.
An odd bird, all the dark parts are pale, washed out brown and the outer primary tips have small white patches at the edge.