Herring Gull- Zilvermeeuw (argentatus & argenteus)

(last update: December 15, 2011 )

Coordinators:
Jean-Michel Sauvage (France)
Mars Muusse (the Netherlands)

Home

hg rings

Herring Gull plumages:

hg 1cy July
hg 1cy August
hg 1cy September
hg 1cy October
hg 1cy November
hg 1cy December

hg 2cy January
hg 2cy February
hg 2cy March
hg 2cy April
hg 2cy May
hg 2cy June
hg 2cy July
hg 2cy August
hg 2cy September
hg 2cy October
hg 2cy November
hg 2cy December

hg 3cy January
hg 3cy February
hg 3cy March
hg 3cy April
hg 3cy May
hg 3cy June
hg 3cy July
hg 3cy August
hg 3cy September
hg 3cy October
hg 3cy November
hg 3cy December

hg sub-ad January
hg sub-ad February
hg sub-ad March
hg sub-ad April
hg sub-ad May
hg sub-ad June
hg sub-ad July
hg sub-ad August
hg sub-ad September
hg sub-ad October
hg sub-ad November
hg sub-ad December

hg ad January
hg ad February
hg ad March
hg ad April
hg ad May
hg ad June
hg ad July
hg ad August
hg ad September
hg ad October
hg ad November
hg ad December

Herring Gull - 2cy January

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".

Common sight at the Dutch beach after storm: foraging argentatus and argenteus Herring Gulls at Scheveningen beach January 24 2003.

2cy Herring Gull: description for January

By January, NW European Herring Gull are in 'first winter' plumage, with most of the scapulars second generation, while birds hatched in northern Russia may 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 (which are often worn away in January), 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 in January, and the legs are flesh-pink with dark shins.

2cy 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. Northern juvenile argentatus may postponed the post-juvenile moult until February, hence retain a complete 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.
1cy January birds in NW Europe have the mantle and 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 (see charts below for argentatus in Poland). 
By January, about half of the argentatus in Poland have all upper scapulars replaced and almost 90% have >75% second generation upper scapular (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.

Moult surveys: some notes

From a "definition point of view", we score 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. By this stage, we don't see any juvenile scapulars, presuming they are now all 2g feathers. 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.

2cy Herring Gull January: tables and charts

rings argenteus: U.K.