Herring Gull- Zilvermeeuw (argentatus & argenteus)

(last update: 7-2-2007)

(4 images) Herring Gull H-108929 3cy/4cy (argenteus), January 2002 - February 2003, Le Portel / Boulogne-sur-Mer, France (50.42N,1.34E).

A typical argenteus ringed in Belgium, Bruxelles H-108929, ringed as pullus on July 08 2000 at Zeebrugge (51.20N 03.11E). The brown second generation primaries lack a mirror on P10. The second generation tail has a broad dark tail-band.
The new scapulars are more or less uniform grey with just a few patterned brownish feathers left in the lower scapulars. Some grey scapulars appear abraded at the fringes already, especially in the upper scapulars.
This Belgian individual has moulted the tertials #3-4 and some wing-coverts in the partial autumn moult as 2cy bird: greater coverts #3-4 have been replaced, median coverts #3-4 and the outer medians from #7 have been replaced and lower lesser coverts #3-4 have been replaced. The new feathers have fresh fringes and tips. The patterns is very similar to the second generation feathers, although a few are typically grey based.
Note the pale grey base of the last moulted central tertial #4, much more adult-like in appearance than the earlier moulted (though same generation) tertial #3.

image below: H-108929 3cy, January 05 2002, Boulogne/Mer, France (50.42N,1.34E).

3 images below: H-108929 4cy, February 07 2003, Boulogne/Mer, France (50.43N-01.37E).

A 4cy argenteus ringed in Belgium: Bruxelles H-108929. This agenteus shows all the familiar characteristics of a 4cy in February:

• note the small white mirror on P10, visible from below,
• the white tips of the third generation primaries are relatively small compared to the primaries of an adult argenteus Herring Gull,
• the tail has obvious vestiges of immaturity: black central markings,
• the lower tertials have much brown patterning and they probably are the oldest tertials (but not necessarily of an earlier generation than the other tertials, as the tertial moulted first in line may appear much more immature than later acquired feathers of the same tract),
• a combination of completely adult-like scapular and mantle region and patterned (barred) greater and median coverts,
• the extensive dark bill-band and greyish iris. 

From January to April, 4cy argenteus moult to so-called "third summer" plumage. The head and under-parts will appear all-white by early May. The tail-feathers, wing-coverts and primaries are not replaced in this moult, therefore most birds strongly resemble "third winter"  birds, although the white primary tips wear away and dark patches start to bleach. The iris is often yellowish, the orbital ring yellowish-orange in argenteus and the bill predominantly yellow with a red gonydeal spot and limited black markings along the culmen by April.