(3 images) Larus fuscus fuscus 2cy, July 15 2003, Tampere, Finland (61.33N 24.59E).
A 2cy fuscus in Finland in July, still showing juvenile outer primaries. Primary moult on the wintering ground was suspended at P8. The inner primaries, P1-P8 were replaced for second generation flight feathers prior to northbound migration. After arrival in Scandinavia, P9 was dropped and is currently growing. Simultaneously, a new moult wave is initiated at P1. The current moult stage: P1 is growing third generation, P2 is missing, P3-P8 are second generation, P9 is growing second generation and P10 still juvenile. All tail-feathers were replaced for second generation feathers as well and the fresh broad white tips on the outer rectrices are clearly visible. Primary moult was not completely fished in the wintering quarters, and the same applies to the secondaries. There is a clear division between the second generation outer secondaries (S1-S11), the growing S12 and the central secondaries which are still juvenile (S13-S15). The innermost secondaries and all the tertials are second generation as well.
In the upper scapulars and outer lower scapulars, new feathers grow in; they appear dark blackish brown, lacking any obvious barring or patterns, except the hardly visible darker shaft-streak.
The complete wing-covert panel has been replaced on the wintering ground, all second generation feathers without any pattern of transversal bars or anchors. The second generation wing-coverts and scapulars are worn pale brown with the fringes worn away and with an obvious dark triangular centre. After arrival in Scandinavia, this bird again started limited moult in the coverts, most obvious in the median coverts. The upper two tertials are missing and in the wing-coverts, new plain blackish coverts are visible in the left wing's central median, innermost lower lesser and innermost greater coverts.
The bare part coloration is still most immature with a pink-based bill and pink legs, typical 2cy in July.
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.