(7 images) Herring Gull DA 2163232cy (argenteus), April 20 2002, Boulogne-sur-Mer, France (50.42N,01.34E).

A bird with a France ring: DA 216323 Museum Paris, ringed as 1cy argenteus on July 23 2001, at Wimereux (50.46N, 01.36E), only 6 km north of Boulogne. In many respects an argenteus Herring Gull, though the barred pattern in the scapulars is very bold and dark, as can be found commonly in michahellis. The orbital ring starts to turn reddish already, where 2cy argenteus normally has a dark brown orbital ring in April and adult argenteus has a yellow-orange orbital ring. Note the rather dark greater and median coverts (especially the outer greater coverts), with broad brown patterns; the paler areas worn a way all the way to the shaft streak. 
These bird origin from NW France, probably ringed close to the village of Wimereux. These NW French birds are in every respect advanced in moult, compared to argenteus from Belgium and the Netherlands (continental NW Europe), advanced in scapular moult, wing-covert moult and in primary moult. Also, they may show a wedge-shaped tail pattern, very like in michahellis. DA 216323 still much show argenteus features and therefore fairly safely identified. However, other birds may much resemble michahellis in early spring, including moulted wing-coverts in the partial autumn moult (e.g. DA 212950). 

Argenteus will show a second partial moult of head and body-feathers in spring (after the previous post-juvenile moult). This partial moult starts in January and ends by May, bringing birds in so-called "first summer" plumage. The head and under-parts will turn white by June, or, as in this bird, already by April.
The juvenile tertials, lesser, lower lesser and median coverts have a notched pattern, and are abraded by April.
The secondaries, primaries and primary coverts are bleached, but the juvenile inner primaries still show a 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.

photo above: DA 216323, April 20 2002, Boulogne-sur-Mer, France (50.42N,01.34E).

4 photo's below: DA 216323, May 16 2002, Boulogne-sur-Mer, France (50.42N,01.34E).

Again Paris DA 216323, at the same location one month ago. By May the complete moult is in progress. In the primaries, P1 and P2 are fully grown, while P3 is just an inch further than the tip of P1. P6-P10 are still juvenile. 
Remarkably, three Paris-ringed Herring Gulls were found with the same moult score. Compared with a sample of 75 randomly chosen 2cy Herring Gulls, only two other birds had dropped p5. Thus, as first figures indicate, Herring Gulls from French colonies may be one full primary ahead in primary moult in spring.
Approximately 8 upper scapulars are replaced for third generation feathers. Greater coverts #1-2 were shed and are growing now, all other greater coverts are still juvenile. In the median coverts, #1-3 are second generation, #4 is missing, #5 is growing and the outermost medians are growing as well. As can be seen in the image, the common moult sequence is followed here: the inner median coverts grow from #1 to #6 and the outer medians grow from the outer-wing inwards to #7, the two moult waves meet at the centre of the covert-row. In the lower lesser coverts, #1-8 are still juvenile, #9 is missing, #10-12 are second generation, #13 and the outer lower lessers are still juvenile. All lesser coverts are still juvenile. The complete tail is still juvenile.

Compared to surrounding 2cy Herring Gulls, the wing-coverts are remarkably well-conserved, deep brown. It may be the dense brown pattern (with a lot of pigmentation) which prevented the wing from severe bleaching.

May 16 2002

May 16 2002

May 16 2002

May 16 2002

2 photo's below: DA 216323, June 14 2002, Boulogne-sur-Mer, France (50.42N,01.34E).

Again Paris Museum DA 216323. The primary moult in Paris-ringed argenteus is noticeably advanced, with P8 missing and P9 juvenile. P6 is already longer than P5.
Note that the majority of scapulars have been moulted to third generation feathers (compare with the previous images, photographed in May). The fresh scapulars have buffish centres. Tertials #1-2 have been replaced last month, #3-4 are missing now and #5-6 are still juvenile. All secondaries and rectrices are still juvenile.
The two inner greater coverts were moulted in May, the next greaters #3-4 are still juvenile and the central greater coverts have been dropped. From the outer-wing second generation greater coverts are growing inwards and the new tips can just be seen in the picture below. The moult in the median coverts has been completed. The lower lesser coverts have been replaced as well and DA 216323 is now moulting the lower rows of lesser coverts. The last juvenile feathers can be found in the upper rows and in the carpal edge.
The first hint of a reddish orbital ring (see April image) could be detected anymore.

June 14 2002

June 14 2002