Larus fuscus

Some 2cy birds on the Tampere dump in Finland in July show characteristics which normally do not associate with classic fuscus. Here is an individual which much resembles graellsii / intermedius, with very restricted post-juvenile moult, no wing-coverts or flight-feathers were moulted in the winter quarters. By mid-July, the primary moult stage is just in line with other NW European gull taxa: P1-P2 are fully grown, P3 is growing, P4-P5 are missing and P6-P10 are still juvenile (PMS = 16). By July 17, the primary moult score slightly increased to 18, with P3 as long as P2 and P4 clearly visible. All rectrices and secondaries are still juvenile and probably the moult in the flight feathers will take place in an ordinary sequence and timing as in intermedius / graellsii.
All the scapulars were included in the post-juvenile moult on the wintering ground. The scapulars show a mix of old and new feathers (in the lower upper scapulars); the new scapulars appear plain dark slate-grey. The old second generation scapulars have no obvious pattern either.
There is no indication of wing-coverts moult on the wintering ground before May, as there are no obvious old worn second generation feathers. The visible fresh feathers suggests an ordinary complete replacement sequence, with the median coverts replaced recently, the new feathers clearly showing a barred pattern; most of the lower lesser coverts replaced, the inner greater coverts replaced and the upper two tertials replaced. Currently, the outer greater coverts are dropped simultaneously with some lesser coverts. The central greater coverts and many lesser coverts (especially in the carpal edge) are still juvenile; within about 7 weeks, the complete wing-covert panel will be renewed. This is approximately the schedule, which can also be found in intermedius. The bare parts are still immature: the bill-base is pink, the legs are pinkish yellow and the iris is brown.

Moult score overlaps with 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.

July 11 2004

July 12 2004

July 17 2004