(5 images) Larus fuscus fuscus 2cy CJUC July 14-17 2003, Tampere, Finland (61.33N 24.59E).
CJUC was ringed in Kanala, Finland, ringed as pullus last summer 2002: June 28 2002 by Risto Juvaste. Hand when ringed: 195 mm.
Considering the upper-part moult, this is another example of typical Finnish fuscus, representing average 2cy fuscus.
Recorded at Tampere: 2003-07-14, 2003-07-15, 2003-07-17, 2003-07-20, 2003-07-23, 2003-07-24, 2003-07-26, 2003-07-27.
After July 27 2003, CJUC wasn't seen again at Tampere dump despite intense visits and may have moved further south from that date on.
The bare part coloration is pretty advanced for 2cy birds, especially when compared to 2cy argenteus, argentatus, graellsii or intermedius from NW Europe. The bill-base is largely yellow and there is already a red gonydeal spot visible on the lower mandible. The legs are yellowish pink and the iris is still dark brown.
Many 2cy fuscus in Finland have the body feathers and head moulted to plain white feathers, with only limited mottling on the sides of the breast and flanks. It's common to find 2cy birds moulting the head in July, as is often indicated by the 'moth-eaten' appearance.
The upper-part moult in the scapulars is advanced, with all upper scapulars and the upper lower scapulars replaced for 3rd generation feathers. The last 2nd generation scapulars can be found in the lowest row of scapulars; they are bleached brown and worn at the fringes.
On the wintering grounds, all wing-coverts have been replaced to 2nd generation feathers. In fuscus, these wing-coverts normally show a simple pattern: they are blackish brown with a wedge-shaped centre. These coverts are about half a year old already and have been exposed to the equatorial sun and now again to the Scandinavian summer sun. Consequently, the feathers are bleached and abraded, especially the first moulted feathers (median coverts, inner greater coverts and lower lesser coverts). Therefore, by mid July a next moult wave has been started, not surprisingly including these first moulted wing-coverts. The new 3rd generation wing-coverts appear dark blackish brown, not unlike adult feathers when fresh. Some of these 3rd generation scapulars and wing-coverts in the right wing are indicated in image 3. Note the difference in colour and abrasion between these new feathers and the adjacent old feathers.
This 2cy fuscus is average in flight feathers moult. On the wintering grounds, all primaries, secondaries and rectrices were moulted to 2nd generation. After arrival in Scandinavia, the inner primaries are included in a next moult wave, and are replaced to 3rd generation. The tip of P1 is already visible and P2 is missing, see the 5th image.
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.