Lesser Black-backed Gull (graellsii & intermedius)

(last update: 28-2-2011 )

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LBBG rings

lbbg 1cy May
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lbbg 1cy December

lbbg 2cy January
lbbg 2cy February
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
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lbbg adult January
lbbg adult February
lbbg adult March
lbbg adult April
lbbg adult May
lbbg adult June
lbbg adult July
lbbg adult August
lbbg adult September
lbbg adult October
lbbg adult Nov - Dec

second calendar year: March - April

Normally, LBBG do not winter in the Netherlands, but depending on winter conditions some may stay in the most south-western point of our country at Westkapelle, Zeeland. Most LBBG present are believed to belong to the race intermedius originating from Denmark to Norway (Vest-Agder). Nevertheless, some local Dutch graellsii -of the type 'Dutch intergrade'- may stay during winter as well, as Dutch colour-ringed individuals showed in winter 2000/2001 at Westkapelle and IJmuiden, near Amsterdam (see distribution maps for locations).
In many plumages, the on average darker intermedius are hard to distinguish from graellsii with certainty so unringed birds can maybe best called LBBG. Most LBBG present in January are adults, but some sub-adults, first and second winters can be seen as well.

In spring, the large groups of LBBG that arrive, contain almost no 2cy birds. By March, adults (probably males) are the first to return to the colonies to occupy the nesting sites, and ring recoveries show there is a strong site fidelity (birds trying to get the exact same spot to build the nest as they did the previous year). By the end of the month, just a few immature LBBG are seen. Throughout May, most 2cy LBBG can be found in large migrating flocks.

Post-juvenile moult in LBBG

The post-juvenile moult in large white-headed gulls in Europe is variable among the species. "The standard" post-juvenile moult is set by Herring Gull (Larus argentatus) and Great Black-backed Gull (L. marinus). These species have a rather restricted post-juvenile moult. Juvenile birds from southern populations normally replace scapulars before the end of the calendar year. They do not include any tertials, wing-coverts or flight feathers in this post-juvenile moult (about 1-2% do replace single wing-coverts; it's a matter of definition if this should be interpreted as 'moult', as it is often not symmetric in the wings). Birds from northern populations often remain in completely juvenile plumage, except for a few small upper scapulars that will be replaced for 2nd generation feathers. However, ringed birds with northern origin sometimes follow a southern moult timing as well. A few illustrations of this "Herring Gull standard" below:

GBBG marinus JP140 1CY, December 04 2011, Boulogne-sur-Mer, France (Jean-Michel Sauvage). From  Vest-Agder, S Norway (57°59'23"N). Most of the upper scapulars and half of the lower scapulars replaced for 2nd gen feathers; coverts and tertials juvenile.	HG argenteus YUAC 2CY, February 09 2013, Calais, France (Jean-Michel Sauvage). From Belgium (51°12'0''N). 2nd gen moult stage: upper scaps 100%, lower scaps 75-99%, total 75-99%. Coverts & tertials = 0% replaced (juvenile).
GBBG marinus 2CY, February 02 2012, IJmuiden, the Netherlands (Mars Muusse). Unringed; no provenance on origin. Illustrative bird representing northern populations: almost all scapulars juvenile; single upper scapulars replaced.	HG argentatus J1490 1CY, November 27 2011, Boulogne-sur-Mer, France (Jean-Michel Sauvage). From island Hornoya, N Norway (70°23'16"N), which is even further than the Russian white K-rings we see in W Europe. Most scapulars still juvenile.
GBBG marinus RUM ES008270 2CY, February 01 2011, Scheveningen, the Netherlands (Mars Muusse). From N Russia (68°46'59 N). Despite northern origin, almost all scapulars replaced.	HG argentatus KV48 1CY, December 31 2006, Oostende, Belgium (Francois Roland). From Murmansk Oblast, White Sea (67.05 N). Most upper scapulars replaced, lower scaps and rest of plumage juvenile.

The gulls depicted above are all example birds with limited post-juvenile moult (no coverts, no tertials, no flight feathers), which is the standard in Herring Gull and Great Black-backed Gull. Two other taxa hatch slightly earlier in the season, and both have a more extensive post-juvenile moult: Caspian Gull (L. cachinnans) and Yellow-legged Gull (L. michahellis). Both species have all scapulars replaced by mid November (except for the odd retarded bird, or relatively late moulting subspecies e.g. L. m. lusitanius). By the end of the year, cachinnans and michahellis have all scapulars replaced, and many birds also replace wing-coverts and tertials in the post-juvenile moult of their hatch year. Moulting wing-coverts or tertials make these birds different from the Herring Gull standard. A few example birds below:

YLG michahellis 1CY, November 25 2006, Boulogne-sur-Mer, France (Mars Muusse). Post-juvenile moult included tertials tt1-3, greater coverts gc1-4, medians mc1-10, lower lesser coverts llc1,2,5,6,8, and lesser coverts lc=1-25% (approx 10x). Scaps: US=1-25% 3g, rest US 2g, LS=100% 2g.	CG cachinnans 2CY, 14 March 2012, Texel, the Netherlands (Herman Bouman). All scapulars replaced, and also upper tertial and many inner wing-coverts: tt1, gc1-3, mc2-9, llc1-6, lc =1-25%.
YLG michahellis 1CY, November 25 2006, Boulogne-sur-Mer, France (Mars Muusse). Post-juvenile moult included tt1-2, gc2-4, mc1-11, llc1,4,6, lc=1-25% (12x). US=1-25% 3g, rest US 2g, LS=100% 2g.	CG cachinnans UKK L-001754 2CY, January 13 2004, Lubna, Poland (Ruud Altenburg). Replaced about half of the coverts, and upper tertials.

Both Caspian and Yellow-legged Gull are early hatching and fletching species, in which the post-juvenile moult starts early in the season. The end of this post-juvenile moult is reached by mid-November. After this date, its normally only a low pace progress in scapular replacement that continues; there will be no new moult gaps in the wing-coverts nor in the tertials. This time schedule is important to remember when dealing with Lesser Black-backed Gull subspecies; western taxon graellsii can match to the schedule of michahellis (albeit slightly -4 weeks- later, but still before the end of the year), while Scandinavian taxa intermedius and fuscus are much later in post-juvenile moult commencement.

In short, it is possible to observe 2CY graellsii and 2CY intermedius side-by-side in N Europe in May or June, both birds looking pretty much the same regarding feather replacement, but the wear in the fringes is completely different. Graellsii replaced wing-coverts early in the winter (October-November), while many intermedius moult these same feather tracts much later, in March-April. Consequently, intermedius looks much tidier and neat in June, where graellsii has a more bleached and worn plumage.

LBBG graellsii  B + M 1CY, December 12 2010, Madrid, Spain (Delfín González). Ringed in Bristol, UK (51º27´N). Most scapulars replaced US=100%, LS=75-99%, TOT SCAPS=75-99%. Wing-coverts and tertials juvenile, except one central mc and single llc replaced.	LBBG intermedius JR2Y 1CY, November 24 2012, Anza, Morocco (Christian Pedersen). Northern origin: Kvannholmen, Norway (69°52'20"N). Completely juvenile plumage, but note a few missing scapulars.
LBBG graellsii  S.L 1CY, November 04 2014, Utrecht, the Netherlands (Frank van der Meer). Ringed at this place: 52°06'55"N. All scaps replaced and few inner wing-coverts replaced. Moult timing and extent match michahellis, and (so far) not recorded in intermedius.	LBBG intermedius  VR9L 1CY, November 21 2012, Agadir, Morocco (Christian Pedersen). From Denmark, southern intermedius popluation. About 75% of the scapulars replaced.
LBBG graellsii  WC4F 2CY, February 14 2007, Agadir, Morocco (Morten Helberg). From Walney, U.K. (54°03'N). Scapulars replaced. Most wing-coverts and tertials still juvenile, but upper TT, inner GC, inner MC and some LC replaced recently. Central GC seem to be missing.	LBBG intermedius J2T9 2CY, March 14 2010, Madrid, Spain (Delfín González). Scapulars replaced. Many wing-coverts and tertials are recently replaced. Still several moult gaps in the llc and lc. The final stage in the wing-covert moult not yet arrived, and it remains to be seen what the final extnt of this moult will be (best observed in June).
LBBG graellsii 24 2CY, April 04 2009, Madrid, Spain (Delfín González). From the  Netherlands (51.41.00N). Classic graellsii: most scapulars replaced now for 3rd gen feathers, wing-coverts & tertials still juvenile.	LBBG intermedius J2T9 2CY,March 08 2009, Madrid, Spain (Delfín González). Ringed as pullus at Sprogø, Denmark (55.20'N) Active post-juvenile moult by March. Illustrative for 2CY birds returning in spring in N Europe, showing most wing-coverts and upper tertials recently replaced.
LBBG graellsii 2CY, April 27 2006, Dordrecht, the Netherlands (Mars Muusse). All scapulars replaced. Also, several wing coverts and upper two tertials replaced in post-juvenile moult on the wintering grounds. This is about the average they look, before starting the complete moult in the summer months.	LBBG intermedius JA8G 2CY, May 09 2007, Simrishamn, Sweden (Jörgen Bernsmo). From Lofoten, Norway (68.08N). Very fresh 2nd gen tertials and wing-coverts, replaced just before northbound migration. Post-juvenile moult included about half of the (inner) wing-coverts and the upper tertials. Rectrices not photographed, but birds such as this may well include tail-feathers in the late winter post-juvenile moult.

There is a tendency to a west-northeast cline regarding extent of the post-juvenile moult. Many of the 2CY April graellsii (ringed birds) on this website show the standard Herring Gull post-juvenile moult: replaced scapulars, but retained juvenile wing-coverts, juvenile tertials and flight feathers. Some graellsii do look more advanced, like the last 2CY graellsii bird from April 27 in Dordrecht, but still most juvenile in its plumage.

The group of ringed intermedius from April also includes some "standard Herring Gull moult strategies" birds, but many birds show more advanced moult. Midway this spectrum are birds with upper tertials replaced, and most of the (visible) inner wing-coverts replaced for 2nd gen, as illustrated by the intermedius 2CY bird from May 09 Simrishamn. The far end of the spectrum contains birds illustrated in the table below: all scapulars replaced, most wing-coverts replaced, all rectrices replaced and even a variable number of secondaries moulted to 2nd gen.
So far, we never encountered ringed 2CY intermedius in spring with replaced primaries. Of course, in western Europe we have records of spring birds with replaced primaries, which looked odd for nominate fuscus (reference for fuscus is birds from S Finland), but unfortunately such birds in western Europe were never ringed, hence no provenance on origin.

From the data on ringed birds, it appears there is a large variation in moult extent in intermedius. This large variation is shared by the eastern cousin 'heuglini'. Visa Rauste photographed a large group of 2CY Lesser Black-backed Gull heuglini, in June in N Russia. The overall appearance and moult strategy in heuglini is remarkable similar to that of intermedius. Except for one (key) difference: quite commonly heuglini include some to many primaries in the post-juvenile moult on the wintering grounds (moult prior to migration). The table below shows a selection of the most advanced 2CY spring intermedius type of birds recorded in western Europe, together with 2CY heuglini birds from the group photographed by Visa. All birds observed in June.

LBBG intermedius type 2CY, June 24 2013, Noordwijk, the Netherlands (Mars Muusse). Extensive moult on winter grounds, including almost all wing-coverts (but note juvenile feathers in carpal edge), and replaced tertials.	LBBG heuglini type 2CY, June 13 2002, Syktyvkar, Russia (Visa Rauste). Common type heuglini: all scapulars, nearly all wing coverts, all tertials, the tail and all secondaries have been renewed. Plain pale grey feathers could well be 3rd gen. Fresh scapulars are plain pale grey with a bluish wash.
LBBG intermedius type 2CY, June 24 2013, Noordwijk, the Netherlands (Mars Muusse). Only few (outer greater) wing-coverts old juvenile, other coverts replaced, together with new tail. Secondaries still juvenile. Complete moult started, P1-P4 missing/growing; P5-P10 old.	LBBG heuglini type 2CY, June 13 2002, Syktyvkar, Russia (Visa Rauste). New wing coverts, tail and secondaries. Also renewed P8-P10 in the right wing and P9-10 in the left. The underwings are strikingly white, as they are in many heuglini. Note the small mirror in P10; this is not known in western taxa.
LBBG intermedius type 2CY, June 24 2013, Noordwijk, the Netherlands (Mars Muusse). Extensive moult including almost all wing-coverts, tertials and rectrices. Complete moult just started in primaries: P1/P5 (P2 already visible as well), and complete moult also indicated by missing inner MC, which will now moult to 3rd generation.	LBBG heuglini type 2CY, June 14 2002, Syktyvkar, Russia (Visa Rauste). Jizz more reminiscent of cachinnans than graellsii. Almost all visible coverts replaced, except central GC. All flight feathers still juvenile (and remarkable fresh looking).
LBBG intermedius type 2CY, June 24 2013, Noordwijk, the Netherlands (Mars Muusse). Replaced tail in spring. Complete moult just started in primaries: P2/P6, with P3 equal to P1 in length.	LBBG heuglini type 2CY, June 14 2002, Syktyvkar, Russia (Visa Rauste). Showing second generation primaries. The moult sequence, however, is unusual, as in the right wing it has retained the juvenile P3 and in the left wing P3-P4. P1-2 are pale grey with a black marking on the outer web near the tip. The rectrices are worn second generation feathers.
LBBG intermedius type 2CY, June 15 2013, Noordwijk, the Netherlands (Maarten van Kleinwee). All secondaries replaced except S1 and S2, all tail feathers replaced. P1 and P2 are fully grown, P3 is missing and/or growing indicating complete moult has started.	LBBG heuglini type 2CY, June 11 2002, Syktyvkar, Russia (Visa Rauste). Boldly marked individual, rectrices and outer secondaries replaced. In the right wing, P1 and P4-P6 are 2nd gen. In the other wing, P1-P2 and P4-P6 have been renewed. The new inner primaries are not really pale grey.