Herring Gull- Zilvermeeuw (argentatus & argenteus)

(last update: 30-9-2009)

Herring Gull (argenteus) YACB 9CY-11CY & 16CY, 2008-2010 & 2015, IJmuiden & Amsterdam, the Netherlands. 

Local argenteus, ringed as pullus on 03 July 2000 at IJmuiden and re-ringed in 2008 when a darvic ring was added. Life history of recoveries below the images (it's a long list, this bird frequently flew in and out Amsterdam where it has been recorded numerous times).

Below: Herring Gull (argenteus) YACB 9CY, July 09 2008, Amsterdam, the Netherlands. Picture: Ruud Altenburg.

Ringed Herring Gull Y.ACB from Forteiland, IJmuiden. Ringed by Fred & Kees as adult on the nest.
Primary Moult Score (PMS): P5-P10 still old, inner primaries not scored. 

Below: Herring Gull (argenteus) YACB 10CY, August 31 2009, IJmuiden, the Netherlands.

From June to December, adult argentatus undergo a complete moult resulting in so-called "winter plumage". By August, the first neat streaks can be found on the crown and hind-neck. After the complete moult is finished by late autumn, the head will show extensive 'winter streaking', often neat fine streaking in sub-adult argentatus. 
By the end of the complete moult (sometimes mid-January in argentatus), the scapulars, mantle, all the wing-coverts, rectrices and remiges will be replaced. From June onwards, the new plain grey wing-coverts are moulted in, starting with the outermost median coverts. 

Adult northern argentatus show a different pattern in the outer primaries, compared to argenteus. In argentatus, especially from northern Scandinavia, the black marking on P5 is very limited and, if black on P5 is present, this black has diffuse edges. But often, these black sub-terminal markings are completely lacking on P5. In Baltic argentatus populations, black on P5 is confined to the outer-web, with sharply defined edges.
Argenteus normally has a black sub-terminal band on the top of p10, dividing the tip from the mirror. If the black sub-terminal band on P10 is broken, the outer-web of p10 still shows black marking. Argentatus normally completely lacks sub-terminal markings, also on the outer-web of P10. Some argentatus completely lack black on the edge of the inner-web, creating a so-called "thayeri pattern". 

The iris is clearly yellow in summer in most argentatus, but some sub-adult argentatus will keep the iris amber to dark brown.

P6 fully grown, P9-P10 old.

Below: Herring Gull (argenteus) YACB 11CY, August 24 2010, IJmuiden, the Netherlands.

P5 fully grown, P8-P10 old.

Below: Herring Gull (argenteus) YACB 16CY, September 24 2015, IJmuiden, the Netherlands.

P7 fully grown, P10 old.

Recoveries for YACB: