Gull H-1243452cy (argenteus), August
08 2003, Boulogne/Mer, France (50.42N, 01.34E).
A 2cy argenteus with a Belgian ring, Museum Bruxelles: H-124345. Ringed as pullus on July 10 2002 at Zeebrugge, Belgium (51.20N 03.11E). Bruxelles H-124345 has P10 still juvenile and P1-P7 are fully grown second generation inner primaries. The partial wing-covert moult has started with the upper tertial which has been shed.
onwards, argenteus has a complete moult during summer to so-called
"second winter" plumage. This complete moult will be finished by
October and overlaps with the partial autumn moult which starts in
September. The head has been moulted in July-August and shows neat fine
streaking by October. The under-parts and rump are pale, mottled with
brown. From mid-May, the scapulars and mantle were replaced for third
generation feathers, starting with the replacement of the lower upper
scapulars. The pattern of the third generation scapulars is more or less
similar to the anchor pattern of the second generation feathers. In
argenteus, some new scapulars may appear adult-like pale
grey, but most new feathers will show an anchor pattern and this still
applies on the new feathers in September. By September, 2cy argenteus
is actively moulting the lowest scapulars, but in the mean time, the upper
scapulars may be moulted again as well. Fresh feathers can be recognized
by the buffish centres.
From early April, the inner primaries
were shed and new second generation primaries grown in. On average, the
last juvenile primary (P10) was shed in the first week of August. The
majority of argenteus complete the primary moult by the first week
of October, when the new second generation P10 will be fully grown. The
new primaries are dark with a tiny pale tip on the fresh flight-feathers.
The four inner primaries show an extensive pale window, as both inner and
outer-web are pale greyish white-brown, contrasting with the outer-wing. A
pale inner-web can still be found in P7.
The second generation tail-feathers show a clear-cut blackish tail-band
with only isolated blackish markings on the white basal half.
From late April to September, argenteus
replace the wing-coverts and tertials, finishing with the central greater
coverts and outer lesser coverts. By September, the average 2cy argenteus
start a simultaneous partial autumn moult in the wing-coverts, including
the upper tertials, some median and lower lesser coverts and often the
inner greater coverts.