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

(last update: June 25, 2012)

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LBBG rings

lbbg 1cy May
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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
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lbbg 3cy July
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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
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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/near-adult: May


Lesser Black-backed Gull sub-adult, May 09 2014, Katwijk, the Netherlands. Classic graellsii type bird. Adut-like flight feathers but still with many immature patterned feathers.

General description

Normally, 5cy in May are extremely hard to separate from adults and the overlap in characteristics is severe. Probably, the only certain clue can be found in ringed birds. Furthermore, 4cy & 5cy LBBG's can be found in colonies, in full May courtship and raising chicks in August; clearly they participate in the the ordinary mating cyclus as adults do. By May, 4cy birds from graellsii populations can be distinguished from adults quite easily (see e.g. image 1 and image 2 and the ringed birds E056E here and E104E here) by e.g.:

  • extensive black on the bill, but black may be lacking
  • pale blue-yellow or white-yellow iris, but may be clear yellow as well
  • pale yellow legs in some birds
  • extensive streaking on the head in some birds
  • many brown-grey coverts, often in the central greater coverts
  • relatively small mirror on P10, often lacking a mirror on P9
  • relatively small white tips on the primaries
  • vermiculate feathers along the trailing edge.

We stress that these features seem to apply on a more extensive scale in graellsii than they do occur in intermedius, which in 4cy may be surprising reminiscent of  adults.

Lesser Black-backed Gull sub-adult, May 22 2014, Katwijk, the Netherlands. Lesser Black-backed Gull sub-adult, May 22 2014, Katwijk, the Netherlands.
Lesser Black-backed Gull sub-adult, May 22 2014, Katwijk, the Netherlands. Lesser Black-backed Gull sub-adult, May 22 2014, Katwijk, the Netherlands.
Lesser Black-backed Gull sub-adult, May 20 2014, Katwijk, the Netherlands. Lesser Black-backed Gull sub-adult, May 22 2014, Katwijk, the Netherlands.
Lesser Black-backed Gull sub-adult, May 20 2014, Katwijk, the Netherlands. Lesser Black-backed Gull sub-adult, May 20 2014, Katwijk, the Netherlands.

Larus argentatus argenteus & Larus fuscus graellsii - Moerdijk, the Netherlands

Black on Greater Primary Coverts as indication for sub-adultness.

Overall, 8% (21 birds) of breeding Herring Gulls showed black on the primary coverts. Black was more frequent in males than females (males 12% (n = 146); females 3% (n = 128); Pearson χ2=6,99; P=0,008; df=1). This difference may be due to an age-sex interaction with respect to colonisation, as males return to the colony to occupy territories at younger age than females (Vercruijsse, 1999). For birds of known age (n = 33), the presence of black on the primary coverts is age-related in Herring Gull (b = -1.393, r2 = 0.408, P = 0.014; df = 1; table 2).

The majority (76%) of breeding Lesser Black-backed Gulls showed black on the primary coverts (n = 962) and we found no marked difference between the sexes (males 78% (n = 434); females 74% (n = 496); Pearson χ2 = 2,622; P = 0,105; df = 1). Our data of known-age Lesser Black-backed Gull (n = 76) suggest that both the number of primaries showing black (b=-0.071, r2=0.072, P=0.020) and the presence of black on the primary coverts (b=-0.189, r2=0.046, P=0.068) are age-related (table 2).

We scored 54 adult birds of known age in 6cy-14cy. 41 birds (75%), in all nine age-classes, were found showing neatly demarcated black pigmentation. 62 breeding LBBG in our sample are considered to be ‘sub-adult birds’ showing primary coverts with extensive black markings, pale brown tips and diffuse borders. 666 birds show limited black markings which are neatly demarcated; we consider such birds to be ‘mature adults’ (see plate 3).


Plate 3. Two example primary covert patterns to illustrate the division between ‘sub-adult’ and ‘adult’ Lesser Black-backed Gulls in our analysis. Left: the greater primary coverts in sub-adult LBBG oHZ show extensive dark centres and diffuse borders. Also note the dark centres on the secondaries and brown-black P9 and P10. Right: LBBG yET with neatly demarcated black markings, which are considered to be still possible in ‘adult’ birds. In fact, LBBG yET was ringed as pullus in June 1995, and now in its 12th calendar year.

.
LBBG
HG
Age
No
Yes
n:
No
Yes
n:
4 cy
.
100
13
.
100
2
5 cy
14
86
8
40
60
5
6 cy
20
80
5
67
33
3
7 cy
17
83
7
80
20
5
8 cy
8
92
14
100
.
5
9 cy
50
50
4
100
.
3
10 cy
57
43
7
100
.
1
11 cy
50
50
6
100
.
3
12 cy
.
100
5
.
.
.
13 cy
33
67
3
100
.
1
14+ cy
.
100
3
100
.
5
Whole sample
25
75
962
92
8
286

Table 2: Black pigmentation on primary coverts in known-age Herring and Lesser Black-backed Gulls (retrapped birds excluded). Values are % for their own age-class. Age in calendar years (CY).

We have illustrated all greater primary wing coverts of known-age Lesser Black-backed Gulls HERE.

Arrested moult in spring in sub-adult LBBG

In spring, it's not uncommon to find LBBG with arrested moult in the primaries in the Netherlands. We do not believe these birds to origin from nominate fuscus colonies, but rather are representatives of both graellsii and intermedius. It is known that nominate fuscus show arrested moult on a very regular basis in spring (see the fuscus sections), but the birds we encounter in NW Europe show all features commonly found in either graellsii or intermedius. We therefore believe that arrested moult is an uncommon but regular phenomenon in the taxa graellsii and intermedius.
Images of LBBG showing arrested moult in spring (!) can be found on these pages:

In most of these birds, the inner primaries look very fresh, without extensive wear in the tips and regarding wear, the outer primaries do not substantially differ what can be found in other birds of similar age-classes. It therefore is believed that most birds follow the common pattern of replacement in the complete moult: i.e. all primaries are moulted between May - November. The inner primaries then are replaced once again on the wintering grounds, somewhere between January and April. 
The intermedius bird at the bottom of this page is illustrative for this: it is still growing P8, so moult has not been finished yet at the time it already migrated north again. The black-ringed T7PF proofs arrested moult also occurs in British LBBG.


Lesser Black-backed Gull sub-adult, May 09 2014, Katwijk, the Netherlands. Classic graellsii type bird. Adut-like flight feathers but still with many immature patterned feathers.

LBBG colonization of Belgium

The Belgian magazine Oriolus published a special edition on gulls, which we here summary, supplied with extra data from the Netherlands. The very informative articles of Oriolus give excellent insight in the development of gull colonies, illustrated with many pictures, tables and charts and is highly recommended read stuff for all interested in gulls.
"The Herring Gull Larus argentatus and Lesser Black-backed Gull Larus fuscus as breeding birds in Flanders, Belgium", by Eric Stienen, Jeroen van Waeyenberge & Harry Vercruijsse, published in Natuur.Oriolus 68(3), July-September 2002, p 104-110.

Introduction

LBbG (L. fuscus) only started breeding in Belgium in the mid 80's, with dramatically increasing numbers in two decades, from one pair in 1985 to 2863 pairs in 2001. Colonization started at the coastal nature reserve "Het Zwin" at Knokke, but numbers never exceeded 40 pairs here. Rapid development LBbG numbers came from the reclaimed industrial harbour area of Zeebrugge from 1987 onwards with 2695 pairs in 2001. Other colonies can be found at the inner harbour of Zeebrugge and roof top breeders at Oostende, south along the Belgian coastline (only 8 pairs in 2001). 

Counting method

Prior to hatching all nests in the harbour of Zeebrugge were counted annually. From a high watching point, the proportion numbers of nesting LBbG's compared to Herring Gulls were estimated. Next step was counting all nests, without discern of species, marking them with a small match stick and discount the proportional ratio afterwards. For lacking annual values, numbers of adjacent years have been used to estimate the annual number, considering the long-term trends and development of locations within the colony concerned.

Table 1 from: The Herring Gull Larus argentatus and Lesser Black-backed Gull Larus fuscus as breeding birds in Flanders, Belgium", E Stienen et all. 
Number of breeding pairs of LBbG in each colony and total numbers in Flanders during the period 1985-2001. * are inter- and extrapolated numbers usd for missing values. 
year Zwin Outer harbour Zeebrugge Inner harbour Zeebrugge Oostende total
1985 3 - - - 3
1986 2 - - - 2
1987 3 - - - 3
1988 1 - - - 1
1989 1* - - - 1
1990 2 0 - - 2
1991 7 2 0 - 9
1992 6 1 1 - 8
1993 8 3 1 - 12
1994 15 14 8 - 37
1995 28 40 11 - 79
1996 15 108 47 - 170
1997 32 218 51 - 301
1998 38 258 30 - 326
1999 40 552 6 4 602
2000 35 1180 50 3 1268
2001 35* 2695 125 8 2863
2002 - - - - -

Results

LBbG only recently settled as breeding species in Belgium and all colonies were occupied after Herring Gulls settled for several years earlier. However, number of Herring Gulls have been low over the first years, sometimes zero over longer periods in the 1960's, and it's only from the mid 1990's, with the expansion of the industrial area of Zeebrugge (especially the Outer harbour of Zeebrugge) that counts exceeded 100's. Outer harbour of Zeebrugge is the only place where numbers of LBbG exceed Herring Gull numbers, now holding over 94% of the Belgian population. The explosive expansion at the Zeebrugge harbour was followed by expansion further south, at Oostende LBbG started breeding on roof tops, as Herring Gulls already had been doing from 1993 onwards, but numbers remain low. During the period of 1992-2001, LBbG numbers almost doubled with an average increase of 99,3%. An estimated 1,8% of all European LBbG's can be found in Belgium. 

Discussion

The rapid expansion in Belgian colonies must be set in an international perspective. LBbG have expanded dramatically over the last decades in NW Europe, now breeding as far south as the Ebro Delta in Spain. In the Netherlands, numbers of breeding LBbG have been growing strongly over the years 1960-2000, now breeding in vast colonies along the coast and inland  industrial complexes and on roof tops. There have been two "grow waves": by protection rules early in the century and another by the increase in food supply from the 1960's (fishery, agriculture and landfills). Now many landfills in the Dutch Delta close, there is a strong decrease in numbers of breeding Herring Gulls at e.g. Saefinghe (Westerschelde), with numbers dropping from over 8.000 to just 1.000. LBbG is an opportunistic species, exploiting these new food supplies and using new human habitats (reclaimed areas and roof tops).
Input at the Belgian colonies initially came from abroad, stimulated by immigration and good nesting habitat, especially the expansion of the Zeebrugge harbour area. The vast sandy areas became extremely suitable for nesting tern species and with vegetation, for gull species as well. While Zeebrugge expanded the industrial area, adjacent colonies in the Dutch Delta and along the British coast reached their maximum and LBbG had to search for new nesting places. In the Netherlands, numbers had been growing already for a much longer period, now resulting in severe competition for nesting sites and traditional colonies in the dunes along the Dutch coast were heavily effected by predation of Fox, forcing all gulls to start breeding at roof tops or to join existing colonies at industrial areas. Similar problems with foxes have been registered by Mike Marsh at Orfordness in Britain. 
In the Netherlands, large areas of colonies have been claimed by industry, increasing pressure on remaining colonies. Considering these trends in nearby large colonies in Britain and the Netherlands, the settlement of LBbG in Zeebrugge was hardly a surprise. 
Ring recoveries suggest LBbG originate from the colonies in the Dutch Delta area (province of Zeeland, north to the mouth of Rhine at Maasvlakte near Rotterdam) and from the British east coast of the southern North Sea. Year 2001, 96 ringed LBbG were counted at Zeebrugge, of which 27 were ringed as adult on the nest at Zeebrugge in previous years. Others were ringed abroad:
27 from Europoort (Dintelhaven), the Netherlands, see map,
35 from Maasvlakte, the Netherlands, see map,
7 from Ordfordness, Britain, across the North Sea. 
In previous years, a ringed LBbG from the inland industrial complex of Moerdijk, the Netherlands was recorded as well. However, remember ring reading may result in exaggerated figures, as not all colonies have ringing programs.
The increase in subsequent years was stimulated largely by high reproduction success of the colony at Zeebrugge itself. The average breeding success may have been over 1.0 over several years. In 2001, reproduction success of ringed LBbG was measured in 82 nests, which had one or both parents colour-ringed. The 82 nests average 1.9 fledged juvenile per pair. This is extremely high and nicely matches the doubling ratio of 99.4%.
Zeebrugge obviously is an attractive breeding place for LBbG. The LBbG chicks diet completely existing of fish (12 regurgitations), where Herring Gull also regurgitate food left overs from garbage and birds (n = 12). LBbG hunt after fish on their own, or helped by fishing trawlers, patrolling the rich fish-grounds of the southern North Sea. The high breeding success in partly based on low predation of LBbG in the colony of Zeebrugge. As said before, the individual range of nests and the distance between nests at Zeebrugge is much higher than the "completed" colony of e.g. Maasvlakte. This figure is mirrored by predation on chicks and eggs; at Maasvlakte predation on neighboring nests is a common phenomenon, one of the factors diminishing breeding success.

future

Given these good breeding results, one may expect to find an ongoing strong increase at Zeebrugge. The LBbG growth rate for 2001 was an astonishing 126%. For sure, the next years will show increasing numbers of breeding LBbG as well. Further inland dispersion and settlements on roof tops can be expected as well, as is already a trend in surrounding countries.
Compared to colonies at Maasvlakte, the individual territorial range at Zeebrugge is much higher (the Maasvlakte colony being "fully occupied"), so a further increase from abroad may be expected. However, as is nicely demonstrated at Maasvlakte, these breeding colonies at industrial development areas are highly vulnerable to tremendous loss of good nesting sites as construction works may start, even within the breeding season, resulting in loss of several 100's of eggs and recently hatched chicks.

 

Sub-adult "graellsii": France.
Lesser Black-backed Gull 4cy-5cy 020A May 2012 & April 2013, Calais, NW France. Picture: Jean-Michel Sauvage.
Lesser Black-backed Gull 4cy 362K May 19 2011, Calais, NW France. Picture: Jean-Michel Sauvage.
Lesser Black-backed Gull 4cy-5cy 963N May 2011 & April 2012, Calais, NW France. Picture: Jean-Michel Sauvage.
Sub-adult "Dutch intergrades": Belgium & Holland.
LBBG 5cy PP4, May 12 2001, Dintelhaven Maasvlakte, the Netherlands. Ringed at the nest at Maasvlakte June 28 1997. 
LBBG 5cy EX07, May 12 2001, Dintelhaven Maasvlakte, the Netherlands. Ringed at the nest at Maasvlakte June 21 1997.
LBBG 5cy E558, May 12 2001, Dintelhaven Maasvlakte, the Netherlands. Ringed at the nest at Maasvlakte June 15 1997.
LBBG 5cy EY84, May 12 2001, Dintelhaven Maasvlakte, the Netherlands. Ringed at the nest at Maasvlakte June 24 1997.
4cy250rE056.jpg (74528 bytes)LBBG 4cy E056E, May 13 2002, Missouriweg, Maasvlakte, the Netherlands (51.59N, 04.02E). A local 4cy bird.
e104r731.jpg (73274 bytes)LBBG 4cy E104E, May 23 & 31 2002, EMO, Maasvlakte, the Netherlands (51.59N, 04.02E). A local 4cy bird.
sub-adult graellsii in May, ringed in the Netherlands. (62557 bytes)LBBG 4cy E119E, May 12 2002, Naaktstrand, Maasvlakte, the Netherlands (51.59N, 04.02E). A local 4cy bird.
sub-adult graellsii in May, ringed in the Netherlands. (75300 bytes)LBBG 5cy E227E, May 16 2004, Dintelhaven, Maasvlakte, the Netherlands (51.59N, 04.02E).
wSA8ad0155.jpg (79862 bytes)LBBG 5cy SA8, May 13 2002, Dintelhaven, Maasvlakte, the Netherlands (51.59N, 04.02E). Ringed at the Maasvlakte as pullus, June 20 1998.
wTT5ad0178.jpg (73130 bytes)LBBG 5cy TT5, May 13 2002, Hartelhaven, Maasvlakte, the Netherlands (51.59N, 04.02E). Ringed at the Maasvlakte as pullus, July 08 1998.
sub-adult graellsii in May, ringed in Belgium. (79079 bytes)LBBG 5cy ACAJ, May 29 2003, Voorhaven, Zeebrugge, Belgium (51.59N,04.02E). Ringed at Zeebrugge as pullus.
sub-adult graellsii in May, ringed in Belgium. (71477 bytes)LBBG 5cy ADAF, May 29 2003, Voorhaven, Zeebrugge, Belgium (51.59N,04.02E). Ringed at Zeebrugge as pullus.
sub-adult graellsii in May, ringed in Belgium. (77469 bytes)LBBG 5cy AHAS, May 29 2003, Voorhaven, Zeebrugge, Belgium (51.59N,04.02E). Ringed at Zeebrugge as pullus.
sub-adult graellsii in May, ringed in Belgium. (77011 bytes)LBBG 5cy AMAK, May 29 2003, Voorhaven, Zeebrugge, Belgium (51.59N,04.02E). Ringed at Zeebrugge as pullus.
sub-adult graellsii in May, ringed in Belgium. (81542 bytes)LBBG 4cy L-82711, May 29 2003, Voorhaven, Zeebrugge, Belgium (51.59N,04.02E).
sub-adult graellsii in May, ringed in Belgium. (79156 bytes)LBBG 5cy L-89427, May 29 2003, Voorhaven, Zeebrugge, Belgium (51.59N,04.02E). No mirror on P10.
sub-adult graellsii in May, ringed in Belgium. (72200 bytes)LBBG 4cy L-92064, May 29 2003, Voorhaven, Zeebrugge, Belgium (51.59N,04.02E).
sub-adult graellsii in May, ringed in Belgium. (82415 bytes)LBBG 4cy L-92821, May 29 2003, Voorhaven, Zeebrugge, Belgium (51.59N,04.02E).
Lesser Black-backed Gull: no black in the primary coverts.
Lesser Black-backed Gull L.f. graellsii 5cy male 20 06 May 2006. No black on primary coverts.
Lesser Black-backed Gull L.f. graellsii 6cy male UA 21 May 2005. No black on primary coverts.
Lesser Black-backed Gull L.f. graellsii 7cy male P8 21 May 2005. No black on primary coverts.
Lesser Black-backed Gull: with black in the primary coverts.
We have illustrated all greater primary wing coverts of known-age Lesser Black-backed Gulls HERE.
Lesser Black-backed Gull L.f. graellsii sub-adult 32 06 May 2006. Black on primary coverts.
Lesser Black-backed Gull L.f. graellsii 12cy ET 04 May 2006. Black on primary coverts.
Lesser Black-backed Gull L.f. graellsii 13cy J3 16 May 2005. Black on primary coverts.
Arrested moult in sub-adults
lbbg480.jpg (69976 bytes)LBBG sub-adult intermedius,Boulogne/Mer, NW France, May 17 2002.
Growing P8.
0738t7pf.jpg (68070 bytes)LBBG 4cy graellsii T7PF, Boulogne/Mer, NW France, May 01 2003. Arrested moult at P6.

Larus argentatus argenteus & Larus fuscus graellsii - Moerdijk, the Netherlands field research: LBBG with extensive black on the primary coverts: sub-adults

Lesser Black-backed Gull L.f. graellsii sub-adult 5X, 08 May 2006.
Lesser Black-backed Gull L.f. graellsii sub-adult 7N, 09 May 2006.
Lesser Black-backed Gull L.f. graellsii sub-adult 7X, 09 May 2006.
Lesser Black-backed Gull L.f. graellsii sub-adult 40, 08 May 2006.
Lesser Black-backed Gull L.f. graellsii sub-adult CV, 06 May 2006.
Lesser Black-backed Gull L.f. graellsii sub-adult E0, 14 May 2006.
Lesser Black-backed Gull L.f. graellsii sub-adult HZ, 14 May 2006.
Lesser Black-backed Gull L.f. graellsii sub-adult LE, 16 May 2006.
Lesser Black-backed Gull L.f. graellsii sub-adult S2, 21 May 2006.
Lesser Black-backed Gull L.f. graellsii sub-adult S9, 21 May 2006.
Lesser Black-backed Gull L.f. graellsii sub-adult 1S, 16 May 2006.
Lesser Black-backed Gull L.f. graellsii sub-adult 1T, 16 May 2006.
Lesser Black-backed Gull L.f. graellsii sub-adult A9, 02 May 2006.
Lesser Black-backed Gull L.f. graellsii sub-adult AY, 02 May 2006.
Lesser Black-backed Gull L.f. graellsii sub-adult K5, 05 May 2006.
Lesser Black-backed Gull L.f. graellsii sub-adult KZ, 05 May 2006.
Lesser Black-backed Gull L.f. graellsii sub-adult LS, 13 May 2006.
Lesser Black-backed Gull L.f. graellsii sub-adult PK, 16 May 2006.
Lesser Black-backed Gull L.f. graellsii sub-adult PZ, 16 May 2006.
Lesser Black-backed Gull L.f. graellsii sub-adult S6, 04 June 2006.
Lesser Black-backed Gull L.f. graellsii sub-adult SA, 23 May 2006.
Lesser Black-backed Gull L.f. graellsii sub-adult 73, 05 May 2005.
 
We have illustrated all greater primary wing coverts of known-age birds HERE.
Lesser Black-backed Gull sub-adult, May 12 2013, Katwijk, the Netherlands.
Lesser Black-backed Gull sub-adult, May 19 2013, Katwijk, the Netherlands.
Lesser Black-backed Gull sub-adult, May 16 2013, Katwijk, the Netherlands.
Lesser Black-backed Gull sub-adult, May 10 2013, Katwijk, the Netherlands.
Lesser Black-backed Gull sub-adult, May 10 2013, Katwijk, the Netherlands.
Lesser Black-backed Gull sub-adult, May 19 2013, Katwijk, the Netherlands.
Lesser Black-backed Gull sub-adult, May 19 2013, Katwijk, the Netherlands.
Lesser Black-backed Gull sub-adult, May 12 2013, Katwijk, the Netherlands.
Lesser Black-backed Gull sub-adult, May 19 2013, Katwijk, the Netherlands. Ssp intermedius.
Lesser Black-backed Gull sub-adult, May 19 2013, Katwijk, the Netherlands.
Lesser Black-backed Gull sub-adult, May 16 2013, Katwijk, the Netherlands.
Lesser Black-backed Gull sub-adult, May 19 2013, Katwijk, the Netherlands.
Lesser Black-backed Gull sub-adult, May 16 2013, Katwijk, the Netherlands.
Lesser Black-backed Gull sub-adult, May 10 2013, Katwijk, the Netherlands.
Lesser Black-backed Gull sub-adult, May 16 2013, Katwijk, the Netherlands.
Lesser Black-backed Gull sub-adult, May 16 2013, Katwijk, the Netherlands.
Lesser Black-backed Gull sub-adult, May 16 2013, Katwijk, the Netherlands.
Lesser Black-backed Gull sub-adult, May 16 2013, Katwijk, the Netherlands.
Lesser Black-backed Gull sub-adult, May 19 2013, Katwijk, the Netherlands.
Lesser Black-backed Gull sub-adult, May 16 2013, Katwijk, the Netherlands.
Lesser Black-backed Gull sub-adult, May 12 2013, Katwijk, the Netherlands.