Lesser Black-backed Gull (graellsii & intermedius)

(last update: 20-2-2015)

second calendar year: September 

By September all 2cy LBBG are moulting primaries, secondaries and many also moult coverts.

Moult in the remiges:

Only a small minority of 2cy LBBG still have old juvenile primaries left in the wing (and this is the last p10, see e.g. picture 2), but many have shed all the juvenile primaries and grow new second generation primaries. Compared to (fresh) juvenile primaries, the top of second generation primaries is rounded. The average moult stage by early September is just above 40, with p7 full-grown, while p8 and p9 are growing. At the end of the month the primary score is over 45, with p7 or p8 full-grown and p9 and p10 growing. 

On average, the outer secondaries (from S1 inwards) are full-grown by September, but in the inner secondaries have been shed. By mid-September, birds can be found with old and new secondaries and gaps of shed feathers. By the end of the month, in most individuals the secondaries have been renewed completely and can be recognized as such by the fresh white tip.

Lesser Black-backed Gull 2CY, September 07 2015, Katwijk, the Netherlands. Retarded bird with small moult gap: P1-P5 new, P6 growing, P7-P10 old juvenile. Old juvenile tail, R2-R3 replaced for 2nd gen (probably in winter). All secondaries old juvenile.	Lesser Black-backed Gull 2CY, September 07 2015, Katwijk, the Netherlands. P1-P6 new, P7 growing, P9-P10 old juvenile. Active moult in tail with R5 still growing; S1 new, S2 missing, other secondaries old juvenile.
Lesser Black-backed Gull intermedius VPE3 2CY, September 06 2015, Katwijk, the Netherlands. From Denmark. P1-P7 fully grown (P7 just longer than P6), P9-P10 old juvenile. S1 new, S2 growing, S3-S9 missing, S10-S17 old juvenile. Large moult gap in outer secondaries and small moult gap below the tertials. New tail with R5-R6 growing.	Lesser Black-backed Gull 2CY, September 04 2015, Utrecht, the Netherlands. P1-P7 fully grown, P8 growing. S1-S9 growing, moult wave towards the body. Small block of central secondaries (S12-S15) old juvenile. Another moult wave from the lower tertials progressing outwards. Tail new 2nd generation.
Lesser Black-backed Gull 2CY, September 04 2015, Utrecht, the Netherlands. P10 still growing. All secondaries and whole tail are new.	Lesser Black-backed Gull 2CY, September 03 2016, Utrecht, the Netherlands. Complete moult: P8/-. PMS=47. Central rectrices moulting to 3rd gen.

Moult in the rectrices:

On average the tail has completely been renewed into second generation. Typically, the contrast is obvious: the base commonly shoes vermiculation on the edge of a broad black tail-band and a small white fringe at the tips. In some individuals, the tail-feathers are abraded already with the tips worn away. Probably, these are the birds that had replaced the complete tail earlier in the season (in spring). The upper-tail coverts normally show broad brown bars.

LBBG intermedius J369N 2CY, May 27 2016, Utrecht, the Netherlands. Bird returned with complete 2nd gen tail. Complete summer moult not started yet.	LBBG intermedius J369N 2CY, September 03 2016, Utrecht, the Netherlands. Complete moult ending with: P7 fully grown. R1-R4 dropped again, now moulting to 3rd gen tail-feathers.
Rectrices moult to 3rd gen in 2CY September birds: evidence from a Norwegian ringed individual Extensive late-winter moult in 2CY birds occurs more commonly in intermedius than it does in graellsii. Such birds with extensive moult return in N Europe with replaced rectrices (2nd gen R). With the tail completely 2nd gen, what will they do in the complete moult in summer? This bird J369N is a nice illustration. All scaps were replaced, and also nearly all the visible wing-coverts replaced for 2nd gen feathers. In the spread wing it shows that the last outermost coverts are still juvenile (like 5x outermost GC, single MC and few LC). All 6 tertials and all 6 pairs of tail-feathers have been replaced too for 2nd gen, but secondaries and primaries remained juvenile (except for 1x central secondary in left wing, but none in the right wing). Fortunately, J369N could be observed throughout the summer months and by early September the tail appeared to be in moult again. Therefore we may conclude that 3rd gen rectrices in September-October 2CY do occur.

Tertials:

The tertials are missing or have been replaced by second generation feathers. The upper two tertials normally are the last to be moulted. The new tertials have an extensive brown-black centre, a white bar at the tip and a sub-terminal anchor pattern at the tip. Sometimes a (single central) tertial may appear grey-centred with an arrow-head; a faint brown pattern along the fringe and a faded white tip (see for instance image 7). Probably, these feathers are already 3^rd generation feathers and have replaced tertials which were included in last autumn's moult.

Coverts:
In all the wing covert bars, active moult may be in progress. In several individuals moult to second generation greater coverts and outer lesser coverts have to be finished as late as the end of September. Normally the median coverts are the first to be moulted, early in the season. By September however, it's still possible to find 2cy LBBG which have shed the median coverts, growing new feathers in. These birds are moulting the median coverts again into 3^rd generation feathers. In pattern they resemble the anchor or barred patterned 2^nd generation feathers (see image 7). Other individuals show the pattern as seen in presumed intermedius LBBGs: plain brown-grey coverts with a pronounced black wedge at the cente (see e.g. image 5 and image 6).

Under-parts and head:

These feather groups have been renewed by neat feathers, with fine streaks on the ear coverts and neat vermiculate bars on the flanks (see e.g. image 1). 

Tables

LBBG 2cy J6PH September 16 2007, IJmuiden, the Netherlands. 2cy & 4cy.