Lesser Black-backed Gull- Kleine Mantelmeeuw (graellsii & intermedius)

(last update: June 26, 2012)

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LBBG rings

lbbg 1cy May
lbbg 1cy June
lbbg 1cy July
lbbg 1cy August
lbbg 1cy September
lbbg 1cy October
lbbg 1cy Nov - Dec

lbbg 2cy Jan-Febr
lbbg 2cy Mar-April
lbbg 2cy May
lbbg 2cy June
lbbg 2cy July
lbbg 2cy August
lbbg 2cy September
lbbg 2cy October
lbbg 2cy Nov - Dec

lbbg 3cy Jan-April
lbbg 3cy May
lbbg 3cy June
lbbg 3cy July
lbbg 3cy August
lbbg 3cy September
lbbg 3cy October
lbbg 3cy Nov - Dec

lbbg sub-ad Jan-April
lbbg sub-ad May
lbbg sub-ad June
lbbg sub-ad July
lbbg sub-ad Aug
lbbg sub-ad Sept
lbbg sub-ad Oct
lbbg sub-ad Nov - Dec

lbbg ad January
lbbg adult February
lbbg adult Mar-April
lbbg adult May
lbbg adult June
lbbg adult July
lbbg ad August
lbbg ad September
lbbg ad October
lbbg ad Nov - Dec

sub-adult: September

Regarding moult pace and strategy, sub-adults don't differ much from full adults. Sometimes it's hard to age sub-adults correct, but on average, some or all of the following features can be found in 4cy:

  • relatively pale bare part coloration compared to full adults, although there is hardly any difference in most sub-adults compared to full adults;
  • black markings on the old rectrices, often isolated limited black spots near the centre, although most rectrices are moulted to completely white tail-feathers by September and sub-adults with old rectrices are rare (but see image 5);
  • p10 with a small mirror, p9 lacking such a mirror and very small white tips on the top of the outer primaries. By August, these tips are worn away and the primaries are brownish, strongly bleached and together with the primary coverts, the outer wing looks brownish (see this preening sub-adult, image 10). In 5cy birds, these outer primary coverts are still not really adult-like, rather blackish with white tips in some cases (see e.g. this sub-adult -presumed 5cy- in image 11);
  • the grey centres of the old secondaries show a brown hue and the tips are abraded. Also, the first moulted secondaries (the outer ones, i.e. S1-S10) may, when they are still not shed, show blackish centres or fine vermiculation at the top half of the feather (see e.g. image 11, where the secondaries are just visible in the open wing);
  • tertials, outer greater coverts or outer lesser coverts (in the carpal edge) show old adult-like feathers with a relative strong brown hue, obvious much stronger than expected in full adult coverts. See image 3.

Used as a single characteristic, the evidence is not very convincing, but individuals that combine these characteristics are probably 4cy or 5cy birds.

Arrested autumn primary moult in sub-adults
In autumn, LBBGs have to decide between moulting the primaries on the breeding grounds or start migrating and shed primaries after arrival in the winter quarters (or main stop-overs). This decision is made on individual considerations and strategy. Ring recoveries revealed that birds (of the same age), born in the same colony, may still be in the Netherlands by early November, while others can be found as south as Morocco. And the strategy may be changed by individuals as well; migrating south as 1cy bird, but stay in the Netherlands in 2cy. Why migration strategy differ so much between two individuals so closely related is unknown, and probably the answer can be found in their ancestors' gene flow. Whatever, the option chosen, opportunistic or conservative, it involves the primary moult schedule. By the end of August, LBBGs leave the Netherlands rapidly and at Maasvlakte numbers fall from several 10.000's to just a few 1.000's within two weeks (end of August, early September). Within those migrating groups, many adults and sub-adults leave with complete old remiges, or arrested primary moult at p1 or p2. But how to prove this hypothesis? 

It's most likely that exactly those sub-adults and adults with suspended and arrested moult are very keen to move south as quick as possible and they probably do not take long breaks on minor stop-overs. For exact numbers on suspended moult, maybe best bet is Portugal or other main stop-overs which are used for a longer time (long enough the fulfill primary moult and find enough food) and check new arriving birds. Another option is video-tape migrating birds from rocky outcrops, where they pass at short distance, and base estimates on the video-stills.
So far, detailed surveys on suspended and arrested moult in (near) adult graellsii/intermedius LBBGs in autumn is lacking, but it certainly occurs, as some pictures show (see e.g. image 20 and image 21). In other sections, arrested moult or expected suspended moult is mentioned as well.

remaining primaries in LBBG Maasvlakte 
- the Netherlands, 28.09.2001 - 
  p4 p5 p6 p7 p8 p9 p10  no
sub-ad* 1 0 2 2 12 14 4 0
adult 2 5 14 23 62 40 10 0
* Sub-adults are presumable in 4 cy.

 

Belgium: Sub-adult graellsii "Dutch intergrades"

Lesser Black-backed Gull 4cy HNASSeptember 17 2011, Boulogne sur mer, NW France. Picture: Jean-Michel Sauvage.

the Netherlands: Sub-adult graellsii "Dutch intergrades"

adult LBBG Dutch intergrade in September, ringed in the Netherlands. (62564 bytes)LBBG Dutch intergrade 4cy NLA 5.411.538, September 02 2003, Westkapelle, the Netherlands.

Germany: Sub-adult graellsii - intermedius transition

adult LBBG Dutch intergrade in September, ringed in the Netherlands. (85708 bytes)LBBG 4cy H.010September 01 2010, Westkapelle, the Netherlands.
adult LBBG Dutch intergrade in September, ringed in the Netherlands. (85708 bytes)LBBG Dutch intergrade H.501 Seen as 3cy and 4cy, Leiden, the Netherlands. Pictures: Maarten van Kleinwee.
adult LBBG Dutch intergrade in September, ringed in the Netherlands. (85708 bytes)LBBG Dutch intergrade H7.6K September 28 2009, Westkapelle, the Netherlands.

Denmark: Sub-adult intermedius

adult LBBG Dutch intergrade in September, ringed in the Netherlands. (85708 bytes)LBBG intermedius V9PN September 23 2010, Westkapelle, the Netherlands.

Norway & Sweden: Sub-adult intermedius

LBBG intermedius, ringed in Norway. (85395 bytes) LBBG 4cy intermedius J0U5 September 20 2010, Westkapelle, the Netherlands. Arrested moult.
LBBG intermedius, ringed in Norway. (85395 bytes) LBBG intermedius JHH1 September 26 2003, IJmuiden, the Netherlands.
adult intermedius lbbg in October, ringed in Norway. (65103 bytes)intermedius JL3G September 08 2008, Madrid, Spain. Photo by Delfín González.
LBBG intermedius, ringed in Norway. (85395 bytes) LBBG intermedius J6PH September 22 2009, IJmuiden, the Netherlands. Also as 2cy.
juvenile LBBG in October, ringed in Norway. (131273 bytes)intermedius sub-adult SVS 8107139 September 24 2007, Westkapelle, the Netherlands.
6297.jpg (79238 bytes)Photo 2: LBBG sub-adult, September 24 2001, IJmuiden, the Netherlands.
6058.jpg (86251 bytes)Photo 3: LBBG sub-adult, September 2 2001, Brouwersdam, the Netherlands.
6059.jpg (91721 bytes)Photo 4: LBBG sub-adult, September 2 2001, Brouwersdam, the Netherlands.
6247.jpg (72571 bytes)Photo 5: LBBG sub-adult, September 17 2001, Vuurtorenvlakte Maasvlakte, the Netherlands.
6253.jpg (99041 bytes)Photo 6: LBBG sub-adult, September 17 2001, Vuurtorenvlakte Maasvlakte, the Netherlands.
6021.jpg (87110 bytes)Photo 7: LBBG sub-adult, September 2 2001, ECT parking Maasvlakte, the Netherlands.
6026.jpg (77041 bytes)Photo 8: LBBG sub-adult?, September 2 2001, ECT parking Maasvlakte, the Netherlands.
6254.jpg (86663 bytes)Photo 9: LBBG sub-adult, September 17 2001, Vuurtorenvlakte Maasvlakte, the Netherlands.
6066.jpg (79726 bytes)Photo 10: LBBG sub-adult?, September 2 2001, Brouwersdam, the Netherlands.
6260.jpg (90794 bytes)Photo 11: LBBG sub-adult, September 17 2001, Vuurtorenvlakte Maasvlakte, the Netherlands.
6019.jpg (78231 bytes)Photo 12: LBBG sub-adult?, September 2 2001, ECT parking Maasvlakte, the Netherlands.
6456.jpg (99454 bytes)Photo 13: LBBG sub-adult, September 30 2001, Le Portel, France.
6025.jpg (84612 bytes)Photo 14: LBBG sub-adult?, September 2 2001, ECT parking Maasvlakte, the Netherlands.
Atypical sub-adult LBBGs in autumn
6565.jpg (88971 bytes)Photo 20: LBBG sub-adult,September 30 2001, Dannes - Le Portel, France. All primaries old, resembling fuscus.
sub-adult LBBG in September. (106435 bytes)Photo 21: LBBG sub-adult, September 0 2 2001, ECT parking Maasvlakte, the Netherlands. Arrested moult at p1.
sub-adult LBBG in September. (71996 bytes)Photo 22: LBBG sub-adult, September 20 2003, IJmuiden, the Netherlands.