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

(last update: 20-2-2011)

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Last update of this page: 31-03-05 10:16

Barth's research: validity of race intermedius?

From the 40's to the 70's, as one of the first persons, the Norwegian ornithologist Edvard Barth questioned the validity of subspecies intermedius, the main form of Lesser Black-backed Gull occurring in Norway. This text is a summary of the article by E. K. Barth and some extra notes about the current situation. Remember that nominate fuscus was more widespread in these days.

In the last decades, much has changed in the distribution of West-European Lesser Black-backed Gulls. Nowadays, they are breeding in large numbers in Britain, Norway and the Netherlands. The breeding range has expanded south along the Atlantic coast to France and the Iberia peninsular. Year 2000 LBBG's can be found from Iberia all the way along the coast north to the White Sea, in the U.K., the Faeroes and on Iceland. Small populations can be found in the NW of the United States. 
In France the sub-species graellsii breed side by side in mixed colonies of michahellis (P. Yésou), it is sympatric with michahellis, and mixed breeding occurs only in very low numbers (which can be regarded typical in the contact zones of expanding species). 
The same can be said about nominate fuscus, which breeds parapatric with heuglini. (They live in different, but neighbouring geographical conditions, without hybridization along the contact zone). 

The group of Lesser Black-backed Gulls is variable in upper-part coloration, measurements and behaviour, varying from the larger graellsii to the smaller fuscus. Intermedius is, as the name suggests intermediate. Fuscus is small, has blackish upper-parts, migrates to the south-east and many individuals show a step-wise moult (Staffel mauser, after Stresemann & Stresemann). The colour of the upper-parts of the larger western representative graellsii is mid-grey and these birds migrate south, along the Atlantic coast. The variation in intermedius varies clinally. Most of the general idea was constructed by the extensive research by the Norwegian ornithologist E. K. Barth, published as Contribution No. 86, Zoological Museum, University of Oslo, called: The circumpolar systematics of Larus argentatus and Larus fuscus with special reference to the Norwegian populations.

Research in the 40's, 50's, 60's and 70's: Edvard K. Barth

Barth, as a Norwegian ornithologist, was much interested in the variation of Larus argentatus and Larus fuscus in Scandinavia, where both species show large intra-specific (sub-population) variation and he collected material from 1942 to 1966, altogether 690 birds. All birds were adults, collected during the breeding season. Based on this material and skins examined in other parts of NW Europe, Barth examined and analyzed  the material on morphological criteria: mantle colour and chroma notation (in Munsell value, measured mechanically with reflectometer equipment), colour of soft parts (in Munsell value), measurements of body-parts (in mm) and egg-dimensions (in mm). Additional information was collected about geographical distribution and migration pattern.

Barth's classification: the third sub-species intermedius

europebarth.jpg (115160 bytes)Map with clustered column charts for Scandinavian location. The aggregate stacked charts, categorized per sub-species can be found by clicking the next three thumbnails.  The last link holds the research data. Although figures have been prepared with most care, I take full responsibility for all errors in any chart and table.

The total material examined can be found in this Table of results from Barth's research. In this table, all data are presented and the complete group of LBBG is classified in three types: the dark form (corresponding with fuscus fuscus), an intermediate form (corresponding with fuscus intermedius) and a British form (corresponding with fuscus graellsii). The division lines between the colour classes are drawn as follows: 
1. dark form: darkness of upper-parts equal to or lower than Munsell value 2.6,
2. intermediate form: darkness of upper-parts between Munsell value 2.6 and 3.2,
3. British form: darkness of upper-parts equal to or higher than Munsell value 3.2.

From the measurements of the upper-parts of all individuals, Barth searched for evidence to classify three sub-species: the well-known graellsii and fuscus and the intermediate intermedius in which he succeeded; from publication of his data onwards, LBBG's have been divided in these three sub-species. The whole of the 'British area' showed only limited overlap with the intermediate samples and the same was true for his measurements of dark versus intermediate samples.

Graellsii has long been considered a sub-species of Larus fuscus, as was already suggested by Brehm in 1867. It's a common breeder in the U.K., the Faeroes and from the 1920's it start colonizing Iceland as well. Barth's measurements in the 60's indicate they all belong to the pale British form and the same could be said about birds from the Netherlands, although the conclusion could only be based on two individuals from this country. 

Fuscus, the very dark mantle form, can be found in the central and northern Baltic area and in northern Norway, forming a marked homogeneous group in the 60's. The picture has changed somewhat since the studies of Barth. Nominate fuscus has had poor breeding successes in e.g. Norway and Finland (see the M. Hario summary) and on the contrary, intermedius has expanded it's range. However, large scale inventories as Barth's research haven't been executed since and his distribution figures still are the most detailed.

Between these two homogeneous "centres" (the countries / islands in the west with graellsii and the Baltic states with fuscus in the east) lays an area inhabited by intermediate coloured birds, both regarding the colour value (darkness) of the upper-parts and regarding the chroma notation (degree of brownish tinge). The data provided by Barth gave rise to acceptance of the intermediate form to sub-specific level: Larus fuscus intermedius. For intermedius as well, a homogeneous population was found by Barth, along the west coast of Norway, near Stavanger. This location was already proposed by Salomonsen in 1963, who situated the centre for intermedius on the island of Rot, just off Stavanger. 
Obvious heterogeneous population were found in the contact zones: southernmost Sweden and the whole of Denmark (especially Anholt). To give an idea of several ringed birds from the area:
An adult ringed in 1989 at Bohuslän (SW Sweden)
An adult ringed in 1992 in Skane (S Sweden)
An adult ringed in 1972 on Anholt (Kattengat)
An adult ringed in 1991 on Anholt (Kattengat)
An adult ringed in 1987 in Jylland (Denmark)
An adult ringed in 1993 in Jylland (Denmark)
A 3cy bird ringed in 1999 in W Denmark 
Several other heterogeneous populations can be found in Kristiansand, on Tarva and in East Finnmark. Areas with heterogeneous population have a marked high coefficient of variation (C.V. value in the table). The general idea of the complete Larus fuscus population is that of a cline: palest birds in the west, darkest birds in the east and intermediate birds in between, with hybridization is small contact zones. Still, this is the general accepted overview of Lesser Black-backed Gulls in Europe (e.g. P Yésou "Systematics of Larus argentatus-cachinnans-fuscus complex revisited", in: Dutch Birding 24-5 2002) and the Dutch Rarity Committee is going one step beyond by splitting the LBBG group in two full species.

Chroma values in Lesser Black-backed Gulls

The research of Barth in the 60's indicates the three forms of Lesser Black-backed Gulls have their own geographical centres, based on the darkness of the upper-parts. Another characteristic measured by Barth pointed in the same direction: the degree of brown tinge on the upper-part feathers (the chroma notation). Observation in the field indicated that the eastern dark form have the upper-parts warmer brown hued, fruity brown, where the western pale form never shows such a warm brown hue, not even on the old abraded feathers. 
The colour value of the chroma notations for the three forms are plotted in the chart left (figure 6 in Barth's paper): The statistical analysis of colour value (ordinate), and the chroma notation (abscissa) of the three forms of L fuscus. Single lines represent the range; rectangles indicate one standard deviation (SD) on either side of the mean; solid bars indicate 99% confidence intervals for the means (99% CID). The number of birds in each sample are given in this chart, the values for SD and 95% CID can be read from the table. 
Again, the distribution of LBBG in NW Europe, based on chroma notation clearly leads to three forms: dark samples (whole Baltic and North Norway to Tarva), Norwegian-Swedish intermediate samples (More to Bohuslän) and the British samples (Iceland, Faeroes, British Isles, the Netherlands). Denmark is plotted between the samples of the dark and intermediate types; representing a mixed population. 

Zones of contact

By the time Barth examined the skins of LBBG (in the 60's), there wasn't much known about the exact contact zone between graellsii and intermedius. Currently, the term "Dutch intergrade" is used for birds breeding in Belgium and the Netherlands north to German coast of the Wadden Sea, showing intermediate characteristics between graellsii and intermedius. The lack of sufficient material is nicely illustrated by the birds from the Netherlands that could be examined by Barth: two individuals. But the contact zones in Scandinavia were quite obvious in his days, although interesting enough two birds collected in northernmost Möre showed Munsell notations close to the British form! 
Barth mentioned two 'geographical centres' for nominate fuscus: the Baltic and northern Norway. Contact zones are located north of Möre along the coast of central western Norway and between Denmark and southern Sweden. These contact zones make it impossible to say something about the origin of a single individual, but on population level, paired clusters can indicate the likelihood of dark birds belonging to intermediate populations and visa versa. Barth uses the Coefficient of Difference (CD value) in line with Mayr (1953). For the area north of Möre, Barth's data give a theoretical joint of non-overlap of 94%. To give a better idea on geographical diverted populations: 

80% of the Tarva birds differ from 100% of the Möre-Bergen birds,
57% of the Möre-Bergen birds differ from 100% of the Tarva birds.

When you take the populations from the geographical centres:
81% of the North Norway birds differ from 100% of the Stavanger birds,
84% of the Stavanger birds differ from 100% of the North Norway birds.

The Danish birds represent a mixed population and doesn't show differences on sub-specific level to either side, nor to the dark form, nor to the intermediate form.

Other measurements

The measurements of bill and wing dimensions shows obvious differences in the three sub-species as well, although not as clear as in mantle coloration. 
Barth also found significant larger eggs of the intermediate form compared to the dark form (within Norway) and the later egg laying date of the dark form. But again, these data are not as convincing as the mantle coloration, as the SD value was rather large.
The soft part coloration is much richer in the northern populations than in populations from southern Norway. Barth measured the swimming webs of Finnmark nominate fuscus to be strong yellow and strong yellowish orange. Birds from Stavanger and the Oslo Fiord showed much less ochre, moderate yellowish orange to very light yellow, although the range was large. The colour of the orbital ring didn't differ much, from reddish orange to brilliant red. 

Migration

Ring recoveries indicate the strong tendency of intermedius to migrate south - south west. Both metal ringed ands color ringed individuals can be found along the coast of the Netherlands and Belgium; and further south along the Atlantic coast of France, Iberia, Morocco and West-Africa. Just check the October and November-December LBBG Sections of this website to find various examples of ringed birds. 
Nominate fuscus predominantly heads south east, as this link of the Finnish Ringing Centres shows: a direct link to the distribution map of Finnish-ringed Larus fuscus fuscus with recoveries of ringed individuals worldwide.

Barth mentions five birds from northern Norway, all migrating in SE direction in line with the direction of migration for Baltic fuscus. In the contact zone of intermedius and fuscus in southern Sweden the picture is clearly illustrated by the findings of Curry-Lindahl (1961) who stated that "no Larus fuscus from Öland or Skane has migrated to the south or south east", they are only found to migrate to the south west. Salomonsen (1963) added that the Danish populations from Bornholm (see Map) and the other islands in eastern Denmark migrate to South Italy and the eastern Mediterranean. Barth presumes these birds of Bornholm, Skane and Öland belong to the sub-species intermedius.

Westkapelle (51.33 N, 3.25 E), situated along the Southwest coast of Holland, is one of the best places to study intermedius LBBG in winter plumage at close range in the Netherlands. As long as it is not freezing, a couple of hundreds remain here during November and December.

All age-classes can be studied at Westkapelle and all pictures (right-hand side) of adult winters were taken in November and December. Based on ring recoveries most present birds originate from Scandinavia (50-80%), particularly Vest-Agder, southern Norway.

Tables

 

fuscuschart_9777_image001.gif (13801 bytes) Chart of Munsell value of fuscus Although figures have been prepared with most care, I take full responsibility for all errors in any chart and table.
fuscuschart_21685_image001.gif (14993 bytes) Chart of Munsell value for intermedius Although figures have been prepared with most care, I take full responsibility for all errors in any chart and table.
fuscuschart_26736_image001.gif (12777 bytes) Chart of Munsell value for graellsii Although figures have been prepared with most care, I take full responsibility for all errors in any chart and table.

Table of results from Barth's research Although figures have been prepared with most care, I take full responsibility for all errors in any chart and table.

 

Tables & Graph

starting date:   22 Oct   29 Oct   05 Nov   12 Nov 19 Nov 
week no: 43 44 45 46 47
REM 0 113 122 2 5 3
REM 1 56 3 0 0 0
REM 2 55 9 0 0 0
REM 3 7 1 0 0 0
REM 4 2 0 0 0 0
REM 5 1 0 0 0 0
REM 6 0 0 0 0 0
REM 7 0 0 0 0 0
REM 8 0 0 0 0 0
REM 9 0 0 0 0 0
REM 10 0 0 0 0 0
0 0 0 0 0
n = 234 135 2 5 3
average P = 0.9 0.2 0.0 0.0 0.0
95% CID = 0.13 0.10 0.00 0.00 0.00
inverse = 1.97 1.98 12.71 2.78 4.30
Variantie (s2) = 0.97 0.33 0.00 0.00 0.00
SD (s) = 0.98 0.57 0.00 0.00 0.00
SE (sx) = 0.06 0.05 0.00 0.00 0.00
           
% class:          
0 48 90 100 100 100
1 24 2 0 0 0
2 24 7 0 0 0
3 3 1 0 0 0
4 1 0 0 0 0
5 0 0 0 0 0
6 0 0 0 0 0
7 0 0 0 0 0
8 0 0 0 0 0
9 0 0 0 0 0
10 0 0 0 0 0
           
  % control: 100 100 100 100 100

  Table above, data for the Netherlands (2000-2010), results for November (aggregated week): number of remaining old primaries in adults.
REM0 = 0 old primaries left (P10 dropped).

Above: Scatter Plot for PMS in adult Lesser Black-backed Gulls. Number of remaining old primaries throughout the year (arrested moult excluded). Sample size is 6.171 birds.

Above: Scatter Plot for PMS in adult Lesser Black-backed Gulls. Number of remaining old primaries for November (arrested moult excluded). Sample size for this graph is 12 ringed birds + 367 unringed birds.

starting date:

29 Oct

05 Nov

12 Nov

26 Nov

week no:

44

45

46

48

NEW 0

0

0

0

0

NEW P1

0

0

0

0

NEW P2

0

0

0

0

NEW P3

1

1

0

0

NEW P4

1

1

0

0

NEW P5

5

6

1

0

NEW P6

10

13

2

0

NEW P7

96

115

31

1

NEW P8

164

145

94

1

NEW P9

71

18

39

22

NEW P10

2

13

11

19

 

 

 

 

 

n =

350

312

178

43

average NEW P =

7.8

7.6

8.1

9.4

95% CID =

0.10

0.11

0.13

0.20

inverse  =

1.97

1.97

1.97

2.02

Variantie (s2) =

0.83

0.91

0.72

0.43

SD (s) =

0.91

0.95

0.85

0.66

SE (sx) =

0.05

0.05

0.06

0.10

 

 

 

 

 

% class

 

 

 

 

0

0

0

0

0

1

0

0

0

0

2

0

0

0

0

3

0

0

0

0

4

0

0

0

0

5

1

2

1

0

6

3

4

1

0

7

27

37

17

2

8

47

46

53

2

9

20

6

22

51

10

1

4

6

44

 

 

 

 

 

% control:

100

100

100

100

  Table above, data for the Netherlands (2000-2010), results for November (aggregated week): number of new, fully grown primaries in adults.
NEW0 = no new primaries visible (arrested moult excluded in this analysis). So either P1 still old, or P1 dropped, but the very tip still not visible.
NEW1 = P1 longest new primary. Range between "at least the tip of P1 is visible" until "tip of P2 still shorter than P1".
NEW2 = P2 longest new primary. NEW3 = etc.

Above: Scatter Plot for PMS in adult Lesser Black-backed Gulls throughout the year. Longest new primary is classified "fully grown". Sample size is 2.969 birds. Birds scored on NEW primaries (arrested moult excluded).

Above: Scatter Plot for PMS in adult Lesser Black-backed Gulls. Scoring on longest new primary, which is classified "fully grown" for November (arrested moult excluded). Sample size for this graph is 9 ringed birds + 874 unringed birds.

The earliest date for birds with missing primaries is 30 April 2006, which is not the earliest day in our complete sample. We scored 98 Lesser Black-backed Gulls prior to that date, some already in February. As can be expected, none of these was in primary moult, and this group was excluded in our further analysis as it will only result in a misfit for the onset of moult, using linear regression statistics.

The last scoring days were in November, with a larger sample (133 adults) on 04 November 2010. From that date we have the last birds with retaining old primaries (13 birds with 1, 2 or even 3 old primaries; 120 birds with no old primaries left). From other days in November, only 10 birds were scored (all ringed adults). They all had no old primaries left.

The first tine a new primary (P1) was visible, was on 08 May 2006. Prior to this date, birds were scored missing inner primaries, but the very tip was still not visible (and therefore not scored). As soon as the tip of P1 was visible, this was automatically scored "fully grown" For the other primaries to be scored fully grown, they had to exceed the previous primary in length (so P2 fully grown, only from when it is longer than P1).

Peter Stewart presents onset of primary moult by scores for caught adult Lesser Black-backed Gulls in the Severn Estuary, U.K., repeated in the table below. To read his results, see this PDF file.  

Table: the number of old remaining primaries present. Compare PMS of adult graellsii at half monthly intervals. Data from the Severn Estuary Gull Group by Peter Stewart: The primary moult of the Lesser Black-backed Gull (special publication No 1). Scores in the Netherlands can be influenced by unringed nominate fuscus, in autumn in particular.

 

Netherlands

Severn Estuary U.K.

 

PMS range

N:

Average PMS

PMS range

N:

Average PMS

1-15 apr

10

49

10

8-10

216

9,9

16-30 apr

10

47

10

10

197

10,0

1-15 may

8-10

849

9,8

8-10

167

9,9

16-31 may

7-10

380

9,7

7-10

76

9,5

1-15 jun

8-10

104

9,6

7-10

33

8,6

16-30 jun
7-10
253
9,7
6-10
65
8,2
1-15 jul
6-10
605
9,2
5-10
176
7,4
16-31 jul
-
-
-
4-8
44
6,4
1-15 aug
3-10
143
6,6
3-10
165
5,2
16-31 aug
2-10
1284
5,4
3-8
127
4,6
1-15 sep
1-10
300
3,6
0-7
234
3,3
16-30 sep
0-7
645
2,9
0-7
173
2,1
1-15 oct
0-9
733
2,2
0-4
328
0,9
16-31 oct
0-10
750
1,3
0-3
244
0,3
1-15 nov
0-3
138
0,2
0-3
604
0,1
16-30 nov
0
5
0
0-1
341
0,0

LINEAR REGRESSION

Onset of primary moult can best be illustrated by a sinusoid for the first few weeks and last weeks, but there appears to be linear dependency over much of the central moult period.

LINEAR REGRESSION FOR OLD REMAINING PRIMARIES

Complete sample: Linear regression (n = 6171, R2= 0.820, sign: P<0,000)
PMS = -0,381* WEEK + 17,967

Ringed adults: Linear regression (n = 2069, R2= 0.800, sign: P<0,000)
PMS = -0,325* WEEK + 16,270

Unringed adult: Linear regression (n = 4102, R2= 0.779, sign: P<0,000)
PMS = -0,513* WEEK + 23,031

LINEAR REGRESSION FOR NEW FULLY GROWN PRIMARIES

Complete sample: Linear regression (n = 2969, R2= 0.930, sign: P<0,000)
PMS = 0,302* WEEK - 5,933

Ringed adults: Linear regression (n = 1209, R2= 0.888, sign: P<0,000)
PMS = 0,252* WEEK - 4,747

Unringed adult: Linear regression (n = 1760, R2= 0.833, sign: P<0,000)
PMS = 0,442* WEEK - 11,906

Adult LBBG (graellsii, intermedius): primary moult score.

new primaries, Nov 06 2001 moult score, Dec 22 2000
p3 1 46 1
p4 1 48 3
p5 6 49 7
p6 13 50 46
p7 107* - -
p8 142 - -
p9 15** - -
p10 12 - -
n: 155 - 57
m: 7,05 - 49,7
n: total.
m: average.
*: incl left green KA5 (Germany), left orange NS2 (Netherlands), right orange AL6 (Netherlands), left white 4 right red H.
**: left orange ES97, EY42 (both Netherlands).

Note: The survey November 06 2001, was done at the Maasvlakte, a mixed group of NW European LBBG races.
Note: The survey December 22 2000, was done at Westkapelle, mainly of the race intermedius.

For explanation of moult score, see Topography Section.

GRAELLSII FROM BRITAIN

ad graellsii LBBG in winter, ringed in Britain.(91291 bytes)Graellsii 6cy FAF 21 November 2003, Westkapelle, the Netherlands. From Orfordness
2cy Dutch LBBG in February. (79773 bytes)LBBG 5cy 4XF November 22 2009, Madrid, Spain. Picture: Delfín González. Also as 3-4cy Febr.
juvenile LBBG, ringed in the Netherlands. LBBG 7cy W5ZG November 15 2009, Madrid, Spain. Photo by Delfín González.
juvenile LBBG, ringed in the Netherlands. LBBG 12cy T5LW December 12 2010, Madrid, Spain. Photo by Delfín González.
LBBG 8cy P:U November 28 2010, Madrid, Spain. Photo by Delfín González.
juvenile LBBG, ringed in the Netherlands. LBBG 7cy J:C December 04 2010, Madrid, Spain. Photo by Delfín González.
Lesser Black-backed Gull 28cy BTO GK38437 2008-2011, Boulogne sur mer, NW France. Picture: Jean-Michel Sauvage.
ad graellsii LBBG in winter, ringed in Britain.Graellsii adult GG-39638 November 20 2000, Westkapelle, the Netherlands.

DUTCH INTERGRADES FROM BELGIUM

Lesser Black-backed Gull adult KCAC November 06 2008, Boulogne-sur-mer, NW France. Picture: Jean-Michel Sauvage.
juvenile LBBG, ringed in the Netherlands. LBBG adult KG.AS November 30 2008, Madrid, Spain. Photo by Delfín González.
ad LBBG in winter, ringed in Belgium. (72874 bytes)LBBG adult L-84891 November 02 2002, Westkapelle, the Netherlands. Primary moult score (PMS) of 49.
ad LBBG in winter, ringed in Belgium.LBBG 5cy H-95698 20 November 2000, Westkapelle, the Netherlands.

DUTCH INTERGRADES FROM HOLLAND

juvenile LBBG, ringed in the Netherlands. LBBG 8cy E568 December 31 2008, Madrid, Spain. Photo by Delfín González.
ad LBBG in winter, ringed in the Netherlands. (93399 bytes)LBBG 12cy MH1 03 November 2004, Westkapelle, the Netherlands. Ringed as a pullus 08.07.1993. Picture Pim Wolf. 
ad LBBG in winter, ringed in the Netherlands. (52136 bytes)LBBG 8cy E836 November 17 2002, Westkapelle, the Netherlands. Primary moult score (PMS): 47. Ringed July 10 1995.
ad LBBG in winter, ringed in the Netherlands. (93562 bytes)LBBG 6cy EJ31 November 12 2000, Westkapelle, the Netherlands. Primary moult score (PMS): 47.
ad LBBG in winter, ringed in the Netherlands. (69413 bytes) LBBG 11cy AT0 Westkapelle, the Netherlands, November 01 2002. Ringed as pullus at June 20 1992 at the Maasvlakte, the Netherlands.
ad LBBG in winter, ringed in the Netherlands. (71138 bytes)LBBG NN1 Westkapelle, the Netherlands, November 01 2002. Ringed as pullus at the Maasvlakte, the Netherlands.
ad LBBG in winter, ringed in the Netherlands. (70744 bytes) LBBG 8cy E139 Westkapelle, the Netherlands, November 02 2002. Ringed as pullus at the Maasvlakte, the Netherlands on June 27 1995.
1cy argenteus in November, ringed in Belgium. (25637 bytes)LBBG 11cy E564 November 20 2005, Westkapelle, the Netherlands.
ad LBBG in winter, ringed in the Netherlands. (20221 bytes) LBBG  E760 Westkapelle, the Netherlands, November 1999 & 2004. Photo by Pim Wolf.
ad LBBG in winter, ringed in the Netherlands. (82801 bytes) LBBG 9cy EE51 Westkapelle, the Netherlands, November 02 2002. Ringed as pullus at the Maasvlakte, the Netherlands.
ad LBBG in winter, ringed in the Netherlands. (68605 bytes)LBBG 7cy EJ47 Westkapelle, the Netherlands, November 02 2002. Ringed as pullus at the Maasvlakte, the Netherlands, June 24 1996. PMS: 46.
ad LBBG in winter, ringed in the Netherlands. (65647 bytes) LBBG 12cy X73 Westkapelle, the Netherlands, November 01 2002. Ringed as pullus at July 03 1991 at the Maasvlakte, the Netherlands. Primary Moult Score (PMS) of 47.
ad LBBG in winter, ringed in the Netherlands. (65647 bytes)LBBG adult 1B December 06 2012, Landfill VRSU de Colmenar Viejo, Madrid, Spain. Picture: Delfín González.
ad LBBG in winter, ringed in the Netherlands. (65647 bytes)LBBG adult D7 August, September 2010 & November 2012, Boulogne-sur-Mer, NW France. Picture: Jean-Michel Sauvage.
Lesser Black-backed Gull adult CC November 01 2010, Outreau-Boulogne, NW France. Picture: Jean-Michel Sauvage.
LBBG adult MH December 31 2008, Madrid, Spain. Photo by Delfín González.
LBBG 6cy X1 December 02 2012, Madrid, Spain. Photo by Delfín González.
ad LBBG in winter, ringed in the Netherlands. (100476 bytes)LBBG EZ 04 November 2004, Westkapelle, the Netherlands. Picture Pim Wolf. 
ad LBBG in winter, ringed in the Netherlands. (62476 bytes)LBBG H5 Westkapelle, the Netherlands, November 15 2003. Ringed as adult at Moerdijk, the Netherlands. PMS: 49.
ad LBBG in winter, ringed in the Netherlands. (65647 bytes)LBBG adult 6K December 02 2012, Landfill VRSU de Colmenar Viejo, Madrid, Spain. Picture: Delfín González.
ad LBBG in Januari-April, ringed in the Netherlands. (60208 bytes)LBBG M.AAA December 13 2009, Madrid, Spain. Photo by Delfín González. Also seen in Sept.
Lesser Black-backed Gull adult Y.AHJ 2009-2011, France & the Netherlands. Pictures: Ruud Altenburg & Jean-Michel Sauvage.
adult LBBG Dutch intergrade in September, ringed in the Netherlands. (80494 bytes)LBBG Y.AKZ 2010-2011, IJmuiden-Westkapelle, the Netherlands.
ad LBBG in winter, ringed in the Netherlands. (49127 bytes) LBBG Arnhem 5...5 Westkapelle, the Netherlands, November 02 2002. Ringed in the Netherlands. PMS of 44.
DUTCH INTERGRADE FROM SPAIN
LBBG adult N567 November 23 2008, Madrid, Spain. Photo by Delfín González.

DUTCH INTERGRADE FROM PORTUGAL

MOI0216a051199.JPG (113735 bytes)Graellsii adult MOI 0216 November 05 1999, Westkapelle, the Netherlands. Primary Moult Score (PMS) of 45.

INTERMEDIUS FROM NORWAY

1cy argenteus in November, ringed in Belgium. (25637 bytes)LBBG adult J908 November 20 2005, Westkapelle, the Netherlands.
juvenile LBBG, ringed in the Netherlands. LBBG adult J51E December 31 2008, Madrid, Spain. Photo by Delfín González.
juvenile LBBG, ringed in the Netherlands. LBBG adult JE8J October & December 2012, Madrid, Spain. Photo by Delfín González.
ad intermedius LBBG in winter, ringed in Norway. Intermedius 467271 November 26 2000, Westkapelle, the Netherlands. PMS: 48.
juvenile LBBG in October, ringed in Norway. (131273 bytes)intermedius 25cy 492441 October & November, Westkapelle, the Netherlands. Picture Pim Wolf.
ad intermedius LBBG in winter, ringed in Norway. (55828 bytes)Intermedius 494670 November 02 2003, Westkapelle, the Netherlands.
ad intermedius LBBG in winter, ringed in Norway. (67394 bytes)Intermedius 4107441 Westkapelle, the Netherlands, November 2002 & 2003. Ringed in southern Norway. PMS: 44, November 01 2003.
ad intermedius LBBG in winter, ringed in Norway. (81610 bytes)Intermedius 4132983 Westkapelle, the Netherlands, November 02 2002. Ringed in southern Norway. PMS: 39 with P9-P10 still old.
ad intermedius LBBG in winter, ringed in Norway. (63063 bytes)Intermedius 4134634 16cy Westkapelle, the Netherlands, November 02 2002. Ringed in southern Norway. PMS: 38 with P9-P10 still old.
ad intermedius LBBG in winter, ringed in Norway. (96422 bytes)intermedius 4141882 November 24 2004, Westkapelle, the Netherlands. Picture Pim Wolf.
ad intermedius LBBG in winter, ringed in Norway. (54995 bytes)Intermedius 4141883 Westkapelle, the Netherlands, November 02 2002. Ringed in southern Norway. PMS: 42.
ad intermedius LBBG in winter, ringed in Norway. (70743 bytes)Intermedius 4164734 Westkapelle, the Netherlands, November 01 2002. PMS: 43.
ad intermedius LBBG in winter, ringed in Norway. (61826 bytes)Intermedius ??69373 Westkapelle, the Netherlands, November 01 2002. Ringed in southern Norway. PMS: 37 with P9-P10 still old.
ad intermedius LBBG in winter, ringed in Norway. (67918 bytes)Intermedius 4178017 Westkapelle, the Netherlands, November 01 2002. PMS: 39 with P10 still old.
ad intermedius LBBG in winter, ringed in Norway. (72844 bytes)Intermedius 41??437 Westkapelle, the Netherlands, November 01 2002. PMS 45 with P8 fully grown.
ad intermedius LBBG in winter, ringed in Norway. Intermedius 4195582 7cy December 21 2000, Westkapelle, the Netherlands. P8 almost fully grown, P9-P10 retarded. PMS: 39. 
ad intermedius LBBG in winter, ringed in Norway. intermedius 4210403 Westkapelle, the Netherlands, November 05 1999. Photo by Pim Wolf. PMS: 42.

INTERMEDIUS FROM SWEDEN

ad intermedius LBBG in winter, ringed in Sweden.Intermedius 12cy 8071437 26 November 2000, Westkapelle, the  Netherlands.
juvenile LBBG in October, ringed in Norway. (131273 bytes)intermedius 11cy & 14cy 8080923 November 2004 & 2007, Westkapelle, the Netherlands.
ad intermedius LBBG in winter, ringed in Sweden. (138843 bytes)LBBG 8081502 30 November 2003, Westkapelle, the Netherlands. Picture Pim Wolf. 
ad intermedius LBBG in winter, ringed in Sweden. Intermedius 9cy  8082746 December 21 2000 Westkapelle, the Netherlands.

INTERMEDIUS FROM DENMARK

juvenile LBBG, ringed in the Netherlands. LBBG adult V.C4F December 04 2010, Madrid, Spain. Photo by Delfín González.
ad intermedius LBBG in winter, ringed in Denmark. Intermedius adult K.234458 26 November 2000, Westkapelle, the Netherlands. Born on Anholt in Kattengat, Denmark. Click the thumbnail to find several other ring-recoveries from Denmark.
ad intermedius LBBG in winter, ringed in Denmark. (114691 bytes)LBBG 423445823 November 2003, Westkapelle, the Netherlands. Picture Pim Wolf. 

UN-RINGED LESSER BLACK-BACKED GULLS

LBBG intermedius and graellsii. Click the thumbnail to find more (unringed) Lesser Black-backed Gulls.