second calendar year: October

By October, all LBBG have left the colonies at the Maasvlakte (the Netherlands). In the pictures you can see what variation can be expected in 2cy LBBG by October in the Netherlands. The variation seems large, but overall, 2cy LBBG may be classified in the following categories:

Category I

Birds with predominantly second generation-like feathers (although some of tehse feathers may in fact be already third generation - often the fresh median covert row). Second generation feathers often show characteristic anchor pattern, barring or deep notches in the fringe. Some 2cy birds replace these feathers in summer for more or less the same kind of feathers. Often the median coverts show barring or club patterns while the greater coverts have dense spaghetti like barring. This group of LBBG don't have grey feathers in the scapular region and in general there are no "adult-like" features at all. So far, we were not able to determine this type to geographical locations and probably such type of LBBG may turn up in both graellsii and intermedius (although there is a tendency to allocate them to graellsii). Several birds of this group originated from U.K. colonies, from Belgium and green AH53 from northern Germany may be classified here as well. When birds of this type are heavily built, strong and robust in appearance, they may be mistaken for Yellow-legged Gulls (michahellis) in 2cy plumage. Although rare in October, some michahellis still have no grey scapulars.

Category II

There is an -intermediate- group: those 2cy LBBG with grey scapulars combined by strongly patterned wing-coverts. As can be seen in the spring section of 3cy, this may be the plumage in which they return next year.

Category III

In October, 2cy LBBG move into the 'steady winter months' where moult is more or less suspended until early spring. However, some LBBG moult throughout the winter, at a lower pace. Others may appear very advanced and may show a 3cy spring plumage already by October, including the all grey adult-like scapular region and some grey median coverts. The lesser and greater coverts are still barred or with a club pattern. There are a few examples in the pictures, and NLA-5.361.744 can be classified to this group. This category of LBBG is as hard to allocate geographically as the other group. 

Partial moult in 2cy intermedius & graellsii

Although an undefined number of -predominantly intermedius- LBBG arrive from the wintering grounds with moulted wing-coverts and scapulars, the general idea is that, in line with large white-headed gulls of NW Europe, Lesser Black-backed Gulls start moulted from late April onwards: the complete moult. This complete moult includes all the wing-coverts, body-feathers, rectrices and of course the remiges. By September, the replacement of the last lesser coverts, inner secondaries and outer rectrices is finished, together with last to outer primaries.
By this time, the partial moult may start, including a various amount of wing-coverts, often a few upper tertials and in some birds a few of the rectrices are moulted again to third generation (all-white or almost all-white) tail-feathers. An example of such a bird with replaced rectrices can be found on this page. 
Partial moult in the wing-coverts is commonly seen in the row which was moulted first last summer: the median covert row. When the complete moult started last summer, the median coverts were dropped first and can look worn at the fringes by October, as several images show (especially in birds of category I). Part of these worn median coverts are dropped again in autumn and replaced by third generation median coverts, which may vary in pattern: in some bird the new median coverts are plain grey, as is seen in 3cy LBBG or older birds. Images of 2cy LBBG with such grey median coverts can be found in category II. Other birds replace the median coverts for new third generation coverts with again a pattern of bars or anchors, much like the pattern found in second generation feathers. Representatives of this type of birds can be found in category I and II. Sometimes these new third generation feathers may be hard to detect, simply because they so much resemble the older second generation feathers. Easiest clue: compare the condition of the fringes. Note however that there is a short time overlap in the moult of the last lesser coverts (and sometimes the growing central greater coverts) and the start of the partial moult in the upper tertials and often in the median and lower lesser coverts.

Median coverts second generation.

Median coverts third generation.

Arrested primary moult in autumn

Arrested or, much better, suspended moult in the primaries is a rare phenomenon in 2cy LBBG graellsii and intermedius. The common moult stage in 2cy LBBG is P9 fully grown and P10 slightly shorter than P9, often at the length of P7 or P8 by the first week of October. Some birds are a little behind in moult with P8 the longest primary.
However, by October it's possible, though highly unusual to find 2cy LBBG still with old juvenile outer primaries. Occasionally such birds can be found while scanning flocks of migrating birds in NW Europe. The phenomenon of arrested or suspended moult seems to be more frequent in spring 3cy LBBG or in autumn sub-adult LBBG. There is a tendency to classify most of these birds in the group of intermedius, as the general characteristics of many these birds suggest: compact, small birds, short legs, short neck, small and slim bill; cute birds in general, somewhat reminiscent of Common Gulls in general jizz. 
2cy birds with suspended primary moult often show suspended moult or delayed moult in the secondaries. An example of suspended primary moult can be seen in this image.

LBBG 2cy October 05 2002, Dannes - Le Portel, NW France. Third generation rectrices in autumn.

LBBG 2cy October 05 2002, Boulogne-sur-Mer, NW France. The outer primaries are still juvenile: moult will be suspended at P8.