nominate Lesser Black-backed Gull (L. fuscus)

(last update: 27-4-2006)

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Larus fuscus fuscus 2cy, July 13 2003, Tampere, Finland (61.33N 24.59E).

In all respects an average 2cy fuscus in Finland in July, with very blackish brown fresh coverts and scapulars, but with the outer primaries P6-P10 still worn juvenile and at least P5 missing. It's hard to tell if primary moult was suspended prior to migration, or commenced in Scandinavia. Given that the vanguard of 2cy fuscus arrive in the first week of June, both option are possible. 2cy fuscus often replace primaries in the post-juvenile moult on the wintering ground, and may arrest this moult to migrate north.
The scapulars show a mix of new feathers and some old second generation scapulars; the new scapulars show a dark centre. 
The complete wing-covert panel has been replaced on the wintering ground, now second generation feathers, most with a similar pattern as the old second generation scapulars. This bird started another moult wave in the coverts and new feathers: two inner greater coverts are replaced, some central lower lesser coverts and a few lesser coverts are replaced as well, showing a similar pattern as the fresh scapulars. Old bleached second generation coverts strongly contrast with the new feathers.

Moult score slightly advanced compared to average intermedius/graellsii in July in NW Europe (see July section), but see e.g. this advanced LBBG in the Netherlands, with P6 fully grown and P7 growing.

Typical Finnish fuscus in July have replaced primaries, rectrices and secondaries, all moulted in a complete post-juvenile moult on the wintering grounds, prior to northbound migration. The new second generation primaries are only a couple of months old and still look dark blackish. The second generation tail-feathers normally still show the white tips, but in some individuals these tips are worn away when 2cy birds arrive back in Scandinavia. Immediately after returning in Scandinavia some 2cy fuscus start a new moult cycle in the inner primaries, now growing in third generation feathers. 
The complete moult in the winter quarters normally start with replacement of the scapulars and mantle-feathers in November to January, but the post-juvenile moult may already start in juvenile birds which are still in Scandinavia in September. The new scapulars often show a simple pattern of a black shaft-streak on a dark brown base. When most of the scapulars are replaced, fuscus start to replace the wing-coverts, in the ordinary sequence that can also be found in other gull taxa in Europe. Wing-covert moult is initiated in two loci, one wave starts in the outermost coverts, one wave starts in the innermost coverts. The two waves normally meet at covert #7-8. Normally the median covert row is the first row which is moulted, followed by the lower lesser coverts, the greater coverts and moult finishes in the outer lesser coverts (the carpal edge). If for whatever reason, moult in the wing-coverts is arrested, this is normally most obvious in the carpal edge and outer greater coverts, containing juvenile feathers which contrast with the other fresh coverts. 
In classical 2cy fuscus, all wing-coverts are replaced to second generation on the wintering grounds, and by mid July in Scandinavia, a next moult wave is initiated, often including the median and lower lesser coverts, the inner greater coverts, upper tertials and scapulars. Bare part coloration may be very immature, including a black bill, but may also be very mature, with a yellow base and a red gonydeal spot on the lower mandible. Still, these birds are only 12 months old.