Lesser Black-backed Gull (graellsii & intermedius)

(last update: 20-2-2017)

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lbbg 2cy January
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lbbg 2cy August
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lbbg 2cy Nov - Dec

lbbg 3cy Jan-April
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lbbg adult January
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lbbg adult August
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lbbg adult October
lbbg adult Nov - Dec

adult: August

adults in the colony

In the Maasvlakte colony many adults try to raise two juveniles. As soon as the fledglings can move, the family tries to find a more comfortable place outside the colony, often at the beach or the near fresh water lakes. By the end of August, 99% of the adult LBBG from the Maasvlakte and their juveniles (approximately 70.000 birds) have left the Maasvlakte and start migrating south (at least leave the immediate feeding grounds around the colony). For a while, they gather at the beach, in mixed groups of different age-classes. 

Several 1.000s of  LBBG can be present up to mid September. In these groups the races graellsii and  intermedius are both present, but hard evidence to categorize adults to certain races is very difficult, and classification is often only possible when birds are banded / ringed. From mid-October numbers of LBBG decrease rapidly. 


Lesser Black-backed Gull graellsii adult, August 21 2015, Katwijk, the Netherlands. Bird in complete moult: P1 new, P3-P10 still old. Local breeding bird with begging young.

moult in the primaries

August is normally a month when primary moult is easy to detect, even on adult birds with folded wings. A small survey of adults in the Maasvlakte colony did not point to a significant primary moult delay in adults with begging youngs in the colony. Individual variation in adult LBBG within a certain colony seems to be at least as large as primary moult variation between colonies of Dutch intergrades and presumed intermedius from Scandinavia. In the table below, remaining old primaries are plotted for mixed groups graellsii, Dutch intergrades and intermedius at the Maasvlakte in the second half of August. Probably, most birds originate from the nearby colony and are Dutch intergrades, but large groups of Scandinavian birds arrive from mid-August onwards. 

Intermedius LBBG from Denmark and southern Norway (intermedius) probably arrive later on the breeding grounds in spring, compared to Dutch intergrades. Subsequently, it may be expected that egg-laying date is later in these populations. It remains to be seen whether or not they show delay in primary moult stage. Such surveys should only involve ringed (certain origin) adults. At this moment, such surveys are impossible; comparable analyses are unreliable by lack of sufficient ring observations.
So far, the hypothesis that intermedius have delay in primary moult could not be verified, but if it's true, the average remaining old primary figure in the table is overestimated (if read as applying to Dutch intergrades) by the input of intermedius arriving in August and later on. On the other hand, it is expected that Dutch intergrades with low moult score (arrested or suspended moult) are keen to leave the Netherlands as soon as possible, leaving a group of adults with relatively high moult score. At this moment, the figures in the table can be used as indication for "what average moult stage can be expected in the second half of August in LBBGs of various origins, present in the Netherlands".

Tables & Graph

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 August (arrested moult excluded). Sample size for this graph is 357 ringed birds + 1137 unringed birds.

starting date:

09 Jul

13 Aug

20-Aug

27-Aug

10 Sep

week no:

28

33

34

35

37

NEW 0

115

3

2

1

0

NEW P1

6

2

4

0

0

NEW P2

0

6

7

2

0

NEW P3

0

7

10

12

0

NEW P4

0

8

1

25

6

NEW P5

0

1

1

5

13

NEW P6

0

0

1

0

11

NEW P7

0

0

0

0

3

NEW P8

0

0

0

0

0

NEW P9

0

0

0

0

0

NEW P10

 

 

 

 

 

 

 

 

 

 

 

n =

121

27

26

45

33

average NEW P =

0.0

2.7

2.4

3.7

5.3

95% CID =

0.04

0.55

0.55

0.27

0.32

inverse  =

1.98

2.06

2.06

2.02

2.04

Variantie (s2) =

0.05

1.92

1.85

0.82

0.79

SD (s) =

0.22

1.39

1.36

0.90

0.89

SE (sx) =

0.02

0.27

0.27

0.13

0.15

 

 

 

 

 

 

% class

 

 

 

 

 

0

95

11

8

2

0

1

5

7

15

0

0

2

0

22

27

4

0

3

0

26

38

27

0

4

0

30

4

56

18

5

0

4

4

11

39

6

0

0

4

0

33

7

0

0

0

0

9

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 August (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 August (arrested moult excluded). Sample size for this graph is 98 ringed 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

Remaining old primaries in adult LBBGs, August 2001.
  10 9 8 7 6 5 4 3 2 n: m: V: SD: SE:
15/08: 6 7 19 21 22 39 18 1 - 133 6,20 2,81 1,68 0,15
21/08: 13 10 22 32 43 102 49 2 - 273 5,82 2,67 1,63 0,10
28/08: 14 14 25 28 93 158 139 47 1 519 5,22 2,54 1,59 0,07
First cell (10, 15/08 = 6) should be read: on August 15 2001, 6 adults had all 10 primaries old, hence showed no primary moult yet (this is about 4% on 133 observed adults that day).
n: observations.
m: average.
V (= s2): variance.
SD (= s): standard deviation.
SE (s / sqr n): standard error.

Survey August 16 2001 Maasvlakte, the Netherlands. Adult primary score in the colony; adults with begging youngs.
p3 old p4 old p5 old p6 old p7 old p8 old n: average:
1 3 3 2 1 1 11 5,82

 

Survey of old primaries in adult LBBG on August 22 2002 at Maasvlakte, the Netherlands (51.57N,04.03E).
  Dintelhaven Missouriweg Papegaaienbek
p1 old 2 - 1
p2 old 4 1 5
p3 old 8 - 8
p4 old 32 1 10
p5 old 44 7 14
p6 old 96 26 12
p7 old 65 12 9
p8 old 3 - -
p9 old 1 - -
p10 old - - -
old prims n
old prim m
old prims SD
old prims SE		 255
5.7
1.28
0.08		 47
6.0
0.92
0.13		 59
4.7
1.59
0.21

Notes:
- For exact location, view the map of Maasvlakte.
- n = observations; m = average; SD = standard deviation; SE (s / sqr n) = standard error.
- In the Dintelhaven sample, another 7 birds were scored with "at least P5 old" in the folded wing, hence P5 or inner primaries still present. In the extreme case these birds had the complete primary set old, this would influence the average m by 0.1.
- old prim m must be read as "primary moult arrived at this stage for remaining old primaries in average adult LBBG".
- Regarding Dintelhaven: Adult primary score in the colony. Scored adults at a small pool which is used to bath and preen by adults from the Dintelhaven colony.
- Regarding Missouriweg: Adult birds feeding begging fledglings in the colony.
- Regarding Papegaaienbek: A mixed flock of adults preening at the sandy shores before returning to the Papegaaienbek colony together with Scandinavian adults using the beaches as stop-over resting point.

 

 

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adult LBBG UK: graellsii
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Lesser Black-backed Gull 5cy RXB August 01 2009, Calais, NW France. Picture: Jean-Michel Sauvage.
Lesser Black-backed Gull graellsii 3.U0 adult, August 31 2017, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 4.Z3 8CY-10CY, October 2015 - August 2017, Torreira beach, Beira Litoral, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 2.F2 adult, August 31 2017, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 3.H5 adult, August 18 2017, Leça beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 5.T9 8CY, August 17 2017, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 8.V3 adult, August 31 2017, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 0CK5 adult, August 31 2017, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii hybrid 2AC3 adult, August 17 2017, Leixões harbour, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 3AU9 adult, October 2015 & 2016, August 2017, Espinho Beach, Espinho, Aveiro, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 4AM6 adult, August 31 2017, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 5CJ1 5CY-6CY, February 2016 & August 2017, Praia da Aguda, V.N.Gaia, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 6CF6 adult, October 2015, September 2016 - February 2017, August 2017, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 6CK8 adult, August 31 2017, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 7AW7 adult, August 17 2017, Matosinhos Beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 7AX0 adult, December 2015, November 2016 & August 2017, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 8AK3 adult, October - December 2015 & October - November 2016 & Augsut 2017, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 8CL6 adult, October 2015 & August 2017, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 8CS1 adult, October 2015 - August 2017, Leixões harbour, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 9CF6 adult, August 2015 & September - October 2016, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
adult LBBG intermedius in September, ringed in Norway. (95609 bytes)Lesser Black-backed Gull graellsii AXS adult, August 31 2017, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii Y98:M adult, August 08 2017, Leixões harbour, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull 28cy BTO GK38437 2008-2011, Boulogne sur mer, NW France. Picture: Jean-Michel Sauvage.
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adult LBBG France: graellsii
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Lesser Black-backed Gull 5,6,8cy 001N 2009, 2010 & 2012, Calais, NW France. Picture: Jean-Michel Sauvage.
Lesser Black-backed Gull 5cy 028A August 04 2013, Calais, NW France. Picture: Walther Leers.
Lesser Black-backed Gull 5cy 161N August 01 2009, Calais, NW France. Picture: Jean-Michel Sauvage.
Lesser Black-backed Gull 6cy 167N August 12 2010, Boulogne sur mer, NW France. Picture: Jean-Michel Sauvage.
Lesser Black-backed Gull 8cy FRP EA639851 / 192N August 2009, April & July 2012, Calais, NW France. Picture: Jean-Michel Sauvage.
Lesser Black-backed Gull 6cy 472N August 19 2012, Boulogne sur mer, NW France. Picture: Jean-Michel Sauvage.
Lesser Black-backed Gull graellsii R:C7A adult, August 07 2015, Leixões Harbour, Matosinhos, Portugal. Picture: José Marques.
adult LBBG intermedius in September, ringed in Norway. (95609 bytes)Lesser Black-backed Gull graellsii R:J4E adult, August 31 2017, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
adult LBBG intermedius in September, ringed in Norway. (95609 bytes)Lesser Black-backed Gull graellsii R:U3S adult, August 31 2017, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
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adult LBBG Belgium: graellsii "Dutch intergrade"
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sub-adult LBBG in August, ringed in Belgium. (53906 bytes)LBBG 6cy AFAF August 15 2003, Westkapelle, the Netherlands. 
Lesser Black-backed Gull 11cy BDAA August 12 2009, Calais, NW France. Picture: Jean-Michel Sauvage.
sub-adult LBBG in August, ringed in Belgium. (76270 bytes)LBBG 7cy BNAH August 01 2003, Zeebrugge, Belgium.
sub-adult LBBG in August, ringed in Belgium. (57738 bytes)LBBG 7+cy BUAM August 01 2003, Zeebrugge, Belgium.
sub-adult LBBG in August, ringed in Belgium. (82012 bytes)LBBG adult GRAR August 20-27 2012, Katwijk, the Netherlands.
LBBG x YLG 9cy MLAT August 29 2010, Boulogne sur mer, NW France. Picture: Jean-Michel Sauvage.
Lesser Black-backed Gull 11CY BLB L-901906 August 27 2014, Boulogne sur mer, NW France. Picture: Jean-Michel Sauvage.
Lesser Black-backed Gull graellsii BLB L-904718 13CY, August 09 2017, Boulogne sur mer, NW France. Picture: Jean-Michel Sauvage.
Lesser Black-backed Gull graellsii BLB L-911577 adult, August 01 2010, Neeltje Jans, the Netherlands.
Lesser Black-backed Gull adult BLB L-916545 August 29 2014, Boulogne sur mer, NW France. Picture: Jean-Michel Sauvage.
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adult LBBG the Netherlands:
graellsii "Dutch intergrade"
.
Lesser Black-backed Gull graellsii 5.D adult, August 31 2017, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 8.A adult, August 31 2017, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull adult H.F August 01 2008, Boulogne-sur-mer, NW France. Picture: Jean-Michel Sauvage.
Lesser Black-backed Gull graellsii H.= adult, July 2015 & August 2017, the Netherlands & Portugal. Picture: Merijn Loeve & José Marques.
Lesser Black-backed Gull adult D.7 August - September 2010, Boulogne sur mer, NW France. Picture: Jean-Michel Sauvage.
1cy argenteus in November, ringed in Belgium. (25637 bytes)Lesser Black-backed Gull graellsii Z.5 adult, August 30 2016, IJmuiden, the Netherlands.
Lesser Black-backed Gull adult 8.5 August 29 2014, Boulogne sur mer, NW France. Picture: Jean-Michel Sauvage.
Lesser Black-backed Gull adult N.E August 16 2014, Boulogne sur mer, NW France. Picture: Jean-Michel Sauvage.
juvenile LBBG in October, ringed in Norway. (131273 bytes)Lesser Black-backed Gull graellsii U3 adult, August 17 2014, Rotterdam, the Netherlands. Picture: Merijn Loeve.
Lesser Black-backed Gull adult H.N August 28 2014, Boulogne sur mer, NW France. Picture: Jean-Michel Sauvage.
juvenile LBBG in October, ringed in Norway. (131273 bytes)Lesser Black-backed Gull graellsii SF adult, May 01 & August 10 2014, Maasvlakte, the Netherlands. Picture: Merijn Loeve.
juvenile LBBG in October, ringed in Norway. (131273 bytes)Lesser Black-backed Gull graellsii H5 adult, May 2006, October 2011 & August 2016, the Netherlands. Picture: Theo Muusse, Maarten van Kleinwee & Henri Zomer.
juvenile LBBG in October, ringed in Norway. (131273 bytes)Lesser Black-backed Gull graellsii 79 adult, 2005, 2013 & 2014, Dordrecht & Moerdijk, the Netherlands. Picture: Merijn Loeve & Muusse brothers.
adult LBBG Dutch intergrade in September, ringed in the Netherlands. (85708 bytes)LBBG adult YABW August 16 2013, Boulogne-sur-Mer, NW France. Picture: Jean-Michel Sauvage.
1cy argenteus in November, ringed in Belgium. (25637 bytes)Lesser Black-backed Gull graellsii Y.ACP adult, August 30 2016, IJmuiden, the Netherlands.
1cy argenteus in November, ringed in Belgium. (25637 bytes) Lesser Black-backed Gull graellsii Y.ASR adult, August 30 2016, IJmuiden, the Netherlands.
Lesser Black-backed Gull adult Y.AST August 2014 & July 2016, Boulogne sur mer, NW France & IJmuiden, the Netherlands. Picture: Jean-Michel Sauvage & Mars Muusse.
1cy argenteus in November, ringed in Belgium. (25637 bytes) Lesser Black-backed Gull graellsii Y.BBU adult, August 22 2015, IJmuiden, the Netherlands.
1cy argenteus in November, ringed in Belgium. (25637 bytes) Lesser Black-backed Gull graellsii Y.BCF adult, August 20 2016, IJmuiden, the Netherlands.
1cy argenteus in November, ringed in Belgium. (25637 bytes)Lesser Black-backed Gull graellsii Y.BVL adult, August 30 2016, IJmuiden, the Netherlands.
1cy argenteus in November, ringed in Belgium. (25637 bytes)Lesser Black-backed Gull graellsii Y.BVP adult, August 30 2016, IJmuiden, the Netherlands.
ad LBBG in Januari-April, ringed in the Netherlands. (60208 bytes)LBBG M.AAA August 22 2010, Madrid, Spain. Photo by Delfín González. Also seen in Dec.
adult LBBG intermedius in September, ringed in Norway. (95609 bytes)Lesser Black-backed Gull graellsii E019 / E 13CY, August 31 2017, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
adult graellsii in May, ringed in the Netherlands. (87040 bytes)Lesser Black-backed Gull graellsii E019 6CY & 11CY, May 2004 & Augsut 2009, Maasvlakte & Westkapelle, the Netherlands.
Lesser Black-backed Gull graellsii E E580 14CY, August 08 2014, Delft, the Netherlands. Picture: Merijn Loeve.
sub-adult LBBG in August, ringed in Belgium. (82012 bytes)Lesser Black-backed Gull graellsii E699 11CY-12CY, September 09 2011 & August 20 2012, Katwijk, the Netherlands.
Lesser Black-backed Gull 12cy RU5 August 08 2009, Calais, NW France. Picture: Jean-Michel Sauvage.
ad lbbg in August, ringed in the Netherlands. (75385 bytes)LBBG 9cy E246 August 24 2003, Texel, the Netherlands. P1 missing.
ad LBBG in August, ringed in the Netherlands. (64808 bytes)LBBG 7cy E914 August 18 2001, Missouriweg Maasvlakte, the Netherlands. P6 shed, P7-P10 are still old. 
Lesser Black-backed Gull 15cy EJ83 August-September 2010, Boulogne sur mer, NW France. Picture: Jean-Michel Sauvage.
ad LBBG in August, ringed in the Netherlands. (59747 bytes)LBBG 9cy EM21 August 15 2004, Missouriweg Maasvlakte, the Netherlands. Ringed as pullus on July 10 1996.
Lesser Black-backed Gull (graellsii) ER29 21CY, August 21 2016, Boulogne-sur-Mer, France (50.44 N - 01.35 E). Picture Jean-Michel Sauvage.
Lesser Black-backed Gull 15cy ES43 August 12 2010, Boulogne sur mer, NW France. Picture: Jean-Michel Sauvage.
Lesser Black-backed Gull 18cy CV8 August 29 2010, Boulogne sur mer, NW France. Picture: Jean-Michel Sauvage.
ad LBBG in August, ringed in the Netherlands. (84068 bytes)LBBG 11cy KR7 August 12 2004, Westkapelle, the Netherlands. Dark individual. Ringed July 07 1993.
ad LBBG in August, ringed in the Netherlands. (84266 bytes)LBBG 9cy EV24 August 12 2004, Westkapelle, the Netherlands. dark individual. Ringed July 12 1996.
ad LBBG in August, ringed in the Netherlands. (72478 bytes)LBBG 11cy ME9 August 12 2004, Westkapelle, the Netherlands. dark individual. Ringed July 01 1993.
ad LBBG in August, ringed in the Netherlands. (57118 bytes)LBBG adult N527 August 04 2010, Heemskerk, the Netherlands. Ringed in Spain in winter.
ad LBBG in August, ringed in the Netherlands. (87390 bytes)LBBG hybrid =3 August 22 2003, IJmuiden, the Netherlands. Ringed in the Netherlands in 1999.
Lesser Black-backed Gull graellsii NLA 5.330.562 19CY, August 18 2015, IJmuiden, the Netherlands.
Lesser Black-backed Gull 14-15cy NLA 5.330.969 September 2010 & August 2011, Boulogne sur mer, NW France. Picture: Jean-Michel Sauvage.
ad LBBG in August, ringed in the Netherlands. (57118 bytes)LBBG adult NLA 5.333.53x August 28 2003, IJmuiden, the Netherlands. Ringed in the Netherlands. P8-P10 are still old, P5 slightly shorter than P4.
Lesser Black-backed Gull adult NLA 5.461.302 2010 & 2012, Boulogne sur mer, NW France. Picture: Jean-Michel Sauvage.
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adult LBBG Denmark: intermedius
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2cy intermedius in July, ringed in Norway. (114585 bytes)6cy LBBG intermediusV3SJ July 2010, August 2014 & October 2014, Utrecht, the Netherlands. Also as 2CY.
Lesser Black-backed Gull 9CY DKC 4139177 August 28 2014, Boulogne sur mer, NW France. Picture: Jean-Michel Sauvage.
ad LBBG in August, ringed in Denmark. (83984 bytes)LBBG adult DKC 4271507 August 12 2004, Westkapelle, the Netherlands. Ringed in Denmark.
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adult LBBG Norway: intermedius
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Lesser Black-backed Gull intermedius J0K1 11CY, August 31 2017, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
ad LBBG in August, ringed in Norway. (87905 bytes)Lesser Black-backed Gull intermedius JC4T adult female, August 04 2015, Boulogne-sur-Mer, France. Picture: Jean-Michel Sauvage.
ad LBBG in August, ringed in Norway. (87905 bytes)Lesser Black-backed Gull intermedius JK1E 6CY, August 02 2017, Tangen Avfallsplass, Askim, Østfold, Norway. Picture: Carl Baggott.
ad LBBG in August, ringed in Norway. (87905 bytes)Lesser Black-backed Gull intermedius JK7K adult, August 02 2017, Tangen Avfallsplass, Askim, Østfold, Norway. Picture: Carl Baggott.
ad LBBG in August, ringed in Norway. (87905 bytes)Lesser Black-backed Gull intermedius JU8A adult, August 02 2017, Tangen Avfallsplass, Askim, Østfold, Norway. Picture: Carl Baggott.
ad LBBG in August, ringed in Norway. (87905 bytes)Lesser Black-backed Gull intermedius J452N adult, August 02 2017, Tangen Avfallsplass, Askim, Østfold, Norway. Picture: Carl Baggott.
ad LBBG in August, ringed in Norway. (87905 bytes)Lesser Black-backed Gull intermedius J4687 adult, August 02 2017, Tangen Avfallsplass, Askim, Østfold, Norway. Picture: Carl Baggott.
ad LBBG in August, ringed in Norway. (87905 bytes)Lesser Black-backed Gull intermedius J556N adult, August 02 2017, Tangen Avfallsplass, Askim, Østfold, Norway. Picture: Carl Baggott.
ad LBBG in August, ringed in Norway. (87905 bytes)Lesser Black-backed Gull intermedius J587N adult, August 02 2017, Tangen Avfallsplass, Askim, Østfold, Norway. Picture: Carl Baggott.
ad LBBG in August, ringed in Norway. (87905 bytes)Lesser Black-backed Gull intermedius J712A adult, August 02 2017, Tangen Avfallsplass, Askim, Østfold, Norway. Picture: Carl Baggott.
Lesser Black-backed Gull intermedius J5JS 12CY, August 21 2017, Boulogne sur mer, NW France. Picture: Jean-Michel Sauvage.
1cy argenteus in November, ringed in Belgium. (25637 bytes)Lesser Black-backed Gull (intermedius) JS47 adult, January 25 2008, Westkapelle & August 23-24 2008, IJmuiden, the Netherlands.
ad LBBG in August, ringed in Norway. (87905 bytes)LBBG adult NOS 4111326 August 29 2003, IJmuiden, the Netherlands. Ringed in Norway. P5-P10 are still old, P3 fully grown.
ad LBBG in August, ringed in Norway. (73700 bytes)LBBG adult NOS 4163669 August 29 2003, IJmuiden, the Netherlands. P7-P10 are still old, P3 fully grown.
ad LBBG in August, ringed in Norway. (66816 bytes)LBBG adult NOS 4191125, August 28 2003, IJmuiden, the Netherlands. P6-P10 are still old, P3 fully grown.
ad LBBG in winter, ringed in the Netherlands. (65647 bytes)LBBG intermedius 19cy NOS 4196745 August 25 2012, Boulogne-sur-Mer, NW France. Picture: Jean-Michel Sauvage.
ad LBBG in August, ringed in Norway. (66598 bytes)LBBG adult NOS 4209478 August 12 2004, Westkapelle, the Netherlands. Ringed in Norway.
ad LBBG in August, ringed in Norway. (64193 bytes)LBBG adult NOS 492081 August 11 2003, Boulogne/Mer, France. P5-P10 are still old. All rectrices old.
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adult LBBG Sweden: intermedius
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ad LBBG in August, ringed in Sweden. (56368 bytes)LBBG adult SVS 8081001 August 28 2003, IJmuiden, the Netherlands. Ringed in Sweden. P5-P10 are still old, P2 is fully grown.
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adult LBBG Portugal: trapped in winter
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Lesser Black-backed Gull adult POL MN02178 August 21 2014, Boulogne sur mer, NW France. Picture: Jean-Michel Sauvage.
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adult LBBG unringed
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sub-adult LBBG in August, ringed in Belgium. (82012 bytes)Lesser Black-backed Gull adult, August 21 2017, Katwijk, the Netherlands.
sub-adult LBBG in August, ringed in Belgium. (82012 bytes)LBBG adult August 20 2012, Katwijk, the Netherlands. P1 still old.
sub-adult LBBG in August, ringed in Belgium. (82012 bytes)LBBG adult August 22 2012, Katwijk, the Netherlands. P1 still old.
sub-adult LBBG in August, ringed in Belgium. (82012 bytes)LBBG adult August 22 2012, Katwijk, the Netherlands. P1 still old.
ad lbbg in August. (66207 bytes)Photo 10: LBBG adult, August 24 2003, Texel, the Netherlands. P1-10 old.
ad lbbg in August. (64438 bytes)Photo 11: LBBG adult, August 24 2003, Texel, the Netherlands. P1-10 old.
sub-adult LBBG in August, ringed in Belgium. (82012 bytes)LBBG adult August 22 2012, Katwijk, the Netherlands. P1/P3.
sub-adult LBBG in August, ringed in Belgium. (82012 bytes)LBBG adult August 22 2012, Katwijk, the Netherlands. P1/P4.
sub-adult LBBG in August, ringed in Belgium. (82012 bytes)LBBG adult August 20 2012, Katwijk, the Netherlands. P1/P4.
sub-adult LBBG in August, ringed in Belgium. (82012 bytes)LBBG adult August 22 2012, Katwijk, the Netherlands. P1/P5.
sub-adult LBBG in August, ringed in Belgium. (82012 bytes)LBBG adult August 20 2012, Katwijk, the Netherlands. P2/P4.
sub-adult LBBG in August, ringed in Belgium. (82012 bytes)LBBG adult August 20 2012, Katwijk, the Netherlands. P2/P4, P6 much older.
sub-adult LBBG in August, ringed in Belgium. (82012 bytes)LBBG adult August 22 2012, Katwijk, the Netherlands. P2/P5.
sub-adult LBBG in August, ringed in Belgium. (82012 bytes)LBBG adult August 20 2012, Katwijk, the Netherlands. P2/P5.
sub-adult LBBG in August, ringed in Belgium. (82012 bytes)LBBG adult August 20 2012, Katwijk, the Netherlands. P2/P5.
sub-adult LBBG in August, ringed in Belgium. (82012 bytes)LBBG adult August 20 2012, Katwijk, the Netherlands. P2/P5.
sub-adult LBBG in August, ringed in Belgium. (82012 bytes)LBBG adult August 20 2012, Katwijk, the Netherlands. P2/P5.
sub-adult LBBG in August, ringed in Belgium. (82012 bytes)LBBG adult August 22 2012, Katwijk, the Netherlands. P2/P6.
sub-adult LBBG in August, ringed in Belgium. (82012 bytes)LBBG adult August 22 2012, Katwijk, the Netherlands. P2/P6.
sub-adult LBBG in August, ringed in Belgium. (82012 bytes)LBBG adult August 20 2012, Katwijk, the Netherlands. P3/P7.
sub-adult LBBG in August, ringed in Belgium. (82012 bytes)LBBG adult August 20 2012, Katwijk, the Netherlands. P3/P7.
sub-adult LBBG in August, ringed in Belgium. (82012 bytes)LBBG adult August 20 2012, Katwijk, the Netherlands. P4/P6.
sub-adult LBBG in August, ringed in Belgium. (82012 bytes)LBBG adult August 20 2012, Katwijk, the Netherlands. P4/P7.
sub-adult LBBG in August, ringed in Belgium. (82012 bytes)LBBG adult August 20 2012, Katwijk, the Netherlands. P4/P8.
sub-adult LBBG in August, ringed in Belgium. (82012 bytes)LBBG adult August 20 2012, Katwijk, the Netherlands. P4/P8.
sub-adult LBBG in August, ringed in Belgium. (82012 bytes)LBBG adult August 22 2012, Katwijk, the Netherlands. P5/P8.
sub-adult LBBG in August, ringed in Belgium. (82012 bytes)LBBG adult August 20 2012, Katwijk, the Netherlands. Together with argenteus and michahellis.
sub-adult LBBG in August, ringed in Belgium. (82012 bytes)LBBG adult August 20 2012, Katwijk, the Netherlands.
sub-adult LBBG in August, ringed in Belgium. (82012 bytes)LBBG adult August 22 2012, Katwijk, the Netherlands.
sub-adult LBBG in August, ringed in Belgium. (82012 bytes)LBBG adult August 22 2012, Katwijk, the Netherlands.

Table below, data for the Netherlands (2000-2010), results for August (aggregated week): number of remaining old primaries in adults.
REM10 = 10 primaries still old (hence, complete moult not started yet).

 

starting date:   30 Jul   06 Aug   13 Aug   20 Aug   27 Aug   03 Sep
week no: 31 32 33 34 35 36
REM 0 0 0 0 0 0 0
REM 1 0 0 0 0 0 0
REM 2 0 0 0 1 3 4
REM 3 0 0 2 6 66 25
REM 4 4 0 24 121 187 24
REM 5 7 1 46 203 182 4
REM 6 13 12 38 89 105 0
REM 7 16 6 23 65 33 0
REM 8 13 3 23 31 25 0
REM 9 1 3 9 15 15 0
REM 10 10 1 6 15 14 0
0     0 0 0
n = 64 26 171 546 630 57
average P = 7.1 6.9 6.1 5.6 5.1 3.5
95% CID = 0.43 0.51 0.25 0.13 0.12 0.19
inverse = 2.00 2.06 1.97 1.96 1.96 2.00
Variantie (s2) = 2.91 1.59 2.65 2.24 2.43 0.54
SD (s) = 1.71 1.26 1.63 1.50 1.56 0.73
SE (sx) = 0.21 0.25 0.12 0.06 0.06 0.10
             
% class:            
0 0 0 0 0 0 0
1 0 0 0 0 0 0
2 0 0 0 0 0 7
3 0 0 1 1 10 44
4 6 0 14 22 30 42
5 11 4 27 37 29 7
6 20 46 22 16 17 0
7 25 23 13 12 5 0
8 20 12 13 6 4 0
9 2 12 5 3 2 0
10 16 4 4 3 2 0
             
  % control: 100 100 100 100 100 100