third calendar year: May
Introduction: Detailed moult description: The
moult of primaries:
Compared
to older birds, the third generation primaries show: smaller tips, P9
lacks a mirror, P10 has a small sized mirror and P3 and P4 show more black
marks (often resulting in a complete sub-terminal band on P4, where adults
only have black on the outer web).
The
moult of tail-feathers:
The
moult of coverts:
More about arrested and suspended
moult. In his article about identification of fuscus LBBG (Birding World, 1998), Lars Jonsson writes about 3cy birds: "Second-summer fuscus is the most likely to be seen as a vagrant... Overall, they are much blacker than the corresponding plumages of graellsii and intermedius and they show much more adult-looking wing coverts. Also, fuscus very typically shows a staggered or incomplete renewal of the greater coverts, where a few brown feathers are retained in an otherwise rather blackish row. On the whole, the more complete renewal of the wing coverts during the pre-breeding moult is markedly different to that of intermedius and graellsii, which typically return for their second summer with a new dark grey 'saddle' but old wing coverts (although quite often the median row will have been renewed, forming a grey band on the middle of the wing)." And further: "I would positively identify a second-summer Lesser Black-backed Gull in May showing predominantly dark wing coverts and very fresh inner six to eight primaries as a fuscus." Although this all is very true for fuscus, it may be an over-simplified analysis of what variation 3cy intermedius may show when they return in May. Most pictures shown here, probably show graellsii LBBG or Dutch intergrade LBBG as they were taken near or in colonies in the Netherlands. But on several occasions, groups of true migrants from Scandinavia can be found at the beach and several "puzzling" individuals were encountered of which a few are shown here. It seems that at least one of the key features to look for (i.e. arrested moult) occurs in intermedius as well and at least an estimated 4-10% of the 3cy LBBG age-class may show this features in spring. And this may be a low estimation, since birds with arrested moult are exactly the birds "in a hurry" and do not take long rests at the stop-over points. It's interesting to see in what way fuscus-like features have to accumulate to make identification as fuscus acceptable. Another web page is enlarging upon and dedicated to several fuscus-features and occurrence of these features in graellsii/intermedius. When intermedius shows arrested moult in the primaries, combined with advanced moult in the upper-parts, these birds can be mistaken for fuscus. At Le Portel, France, three such LBBG were present early May 2001, including a very dark, gentle (female) intermedius. The bird's characteristics strongly approached those said to be diagnostic for fuscus. Very dark (blackish) gentle (female?) second summer intermedius, which show very advanced moult in the upper-parts, combined with arrested moult in the primaries do occur and approach fuscus in both coloration and general structure. Now we have come across a few LBBGs, showing third generation P1-P6 or P1-P7, it's hard to select diagnostic features to distinguish between the two. Arrested moult or suspended
moult? Arrested moult: in autumn or spring? Dutch 3cy LBBG at the Maasvlakte |
E304 LBBG 3cy, May 31 2002, Maasvlakte (Papegaaiebek), the Netherlands. Ringed in the Netherlands. |
5.366.282 LBBG 3cy, May 07 2003, Maasvlakte (Dintelhaven), the Netherlands. Ringed in the Netherlands. Arrested primary moult. |
5.366.284 LBBG 3cy, May 27 2003, Maasvlakte (Dintelhaven), the Netherlands. Ringed in the Netherlands. |
L-97134 LBBG 3cy, May 03 2003, Voorhaven, Zeebrugge, Belgium (51.59N 04.02E). Ringed in Belgium. |
JUH6 LBBG 3cy, May 27 2001, Zeebrugge, Belgium. Picture by Peter Adriaens. An intermedius, born at Vest-Agder, southern Norway, with arrested moult at P9. May 2001 several LBBG with arrested moult were recorded. Most probably they origin from Norwegian colonies. |
DKC 4280679 LBBG intermedius 3cy, May 03 2004, EMO Maasvlakte, the Netherlands. Ringed in Denmark. Arrested moult at P2. |
Photo 1: LBBG 3cy, May 18 2000, Maasvlakte (Papegaaiebek), the Netherlands. |
Photo 2: LBBG 3cy, May 12 2001, Missouriweg Maasvlakte, the Netherlands. Note the long-necked and long-legged appearance in this 2nd summer. |
Photo 3: LBBG 3cy, May 25 2000, Maasvlakte (Papegaaiebek), the Netherlands. |
Photo 4: LBBG 3cy, May 25 2000, Maasvlakte (Papegaaiebek), the Netherlands. A very usual bird. |
Photo 5: LBBG 3cy, May 12 2001, Missouriweg Maasvlakte, the Netherlands. Bare parts like 2cy LBBG, but advanced upper-parts. |
Photo 6: LBBG 3cy, May 25 2000, Maasvlakte (Papegaaiebek), the Netherlands. |
Photo 7: LBBG 3cy, May 12 2001, Missouriweg Maasvlakte, the Netherlands. In the upper parts, moult progresses slowly, only half of the scapulars are 3rd generation grey feathers. Tail with many brown marks. |
Photo 8: 3cy LBBG, May 25 2000, Maasvlakte (Nachtegalenkeet), the Netherlands. Apart from dark iris, bare parts typically, including red orbital ring. |
Photo 10: LBBG 3cy, May 26 2000 Maasvlakte (Naaktstrand), the Netherlands. Third and second summer side-by-side. Note the very pale inner primaries. |
Photo 11: LBBG 3cy, May 23 2002 Missouriweg, Maasvlakte, the Netherlands. An individual with very obvious head-streaking in May. |
Photo 12: LBBGs 3cy, May 2000, Maasvlakte. Compare structural differences in flight between both birds. |
Photo 14; LBBG 3cy, Maasvlakte, May 26 2000. Correct ageing of immature LBBGs may be difficult. |
Photo 15: LBBG 3cy, May 12 2001, Dintelhaven Maasvlakte, the Netherlands. This typical 2nd summer already frequents the colony. The mantle and scapulars form a grey saddle. |
Photo 16: LBBG 3cy, May 12 2001, Missouriweg Maasvlakte, the Netherlands. |
Photo 17: LBBG 3cy, May 12 2001, Naaktstrand Maasvlakte, the Netherlands. Prior to heading north, almost all the median coverts and the inner greater coverts were shed in one wave. |
Photo 18: LBBG 3cy, May 13 2002, Missouriweg, Maasvlakte, the Netherlands. Randomly a few coverts were included in the partial moult. |
Photo 19: LBBG 3cy, May 31 2002, EMO, Maasvlakte, the Netherlands. |
LBBG'S WITH FUSCUS FEATURES |
Photo 30: LBBG with fuscus features 3cy, May 5 2001, Dannes, France. A 3cy LBBG with advanced moult stage. P1-p6 show white tips on fresh primaries. P7-p10 are still 2nd generation. The dark plumage combined by arrested moult and slender expression strongly favours fuscus. |
Photo 31: LBBG intermedius 3cy, May 5 2001, Dannes, France. 3cy winter, as the primaries suggest. In many respects very advanced and resembling a 4cy LBBG. Such advanced 3cy LBBG can be found in large groups of intermedius in spring. |
Photo 32: LBBG intermedius 3cy, May 4 2001, Le Portel, France. Probably a 3cy LBBG, not a delayed 4cy, based on p7-10, black bill-band and secondaries. |
Photo 33: LBBG 3cy, May 11 2001, Naaktstrand Maasvlakte, the Netherlands. In both graellsii and intermedius, arrested moult is a rare phenomenon. |
Photo 34: LBBG 3cy / sub-adult intermedius, Le Portel - Boulogne/Mer, NW France, May 17 2002. Actively growing p8. |
Photo 35: LBBG 3cy, May 27 2003, Missouriweg Maasvlakte, the Netherlands. Another example of 3cy LBBG with growing primaries in spring: P8 nearly fully grown. |