Lesser Black-backed Gull - L. fuscus graellsii & intermedius

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

(last update: 17-1-2011)

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adult: May

Lesser Black-backed Gull adult, May 09 2014, Katwijk, the Netherlands. Classic graellsii type bird. Complete moult not started: P1-P10 old.

Many photographs were taken at two colonies at the Maasvlakte (51'56 N 04'00 E). The Maasvlakte, situated along the Dutch North Sea coast near Rotterdam, is a large harbour complex (see the maps in the distribution section). The vacant sites, not occupied by industrial companies, accommodate large colonies of Lesser Black-backed Gulls (LBBG) and Herring Gulls (HG).

Mixed breeding

Dutch LBBG colonies are probably a result of colonization by both intermedius (from Scandinavia) and graellsii (from Great-Britain) during the 1930s, and are often referred to as 'Dutch intergrades'. It is not unlikely that "Herring Gull blood" is involved as well, as mixed breeding between HG and LBBG was not uncommon during the early colonization period (yet, for the last decades these mixed pairs are not seen). From the 1990's, mixed pairs with michahellis can be found annually.

Nowadays ringed adults from several foreign colonies can be found within the Maasvlakte colony. Mixed breeding does occur with Yellow-legged Gulls (about 10 mixed pairs annually), resulting in mixed characteristics and therefore making identification in some birds pretty hard. An example of such a mixed couple can be found on this page, the birds were photographed in April and May 2002. A male Lesser Black-backed Gull has paired with a female Yellow-legged Gull. Some birds have the upper-parts a shade of grey paler than normally seen in LBBG, and when this is combined with other features as an orange orbital ring, one may expect some Herring Gull influences.

Location of breeding

As can be seen in the images, adult birds are very strict in choosing a place in the colony. Research in Herring Gulls (in the Netherlands by H. Vercruijsse) revealed that almost all sub-adult Herring Gulls visited the colony of birth at least once in their life to investigate the possibilities for nesting in later years. In their third year, Herring Gulls (but Lesser Black-backed Gulls as well) can be found in the colonies on an extensive scale. Every colony holds at least a few immature birds, any time in the breeding season. It's not said that they will breed there in later years, they might just be on investigation to find out whether it will be a profitable decision. Once the breeding site is chosen, adults are very strict in returning to this site in future.

Primary Moult Scores in adult LBBG:

Year 2003 we did some preliminary research on primary moult scores in adult LBBG. In total, we scored about 1400 birds from early April to mid October. This research will be used to do some more fundamental research in tear 2003-2004. First results for May can be read from the tables below. Most birds had P1 still present, but from late May onwards, adult LBBG increasingly shed P1. The last survey is from Zeebrugge, May 30 with most advanced bird missing P1 and P2 (score 8, in metal ringed L-62174 and orange EX22, ringed July 03 1997, now in 7cy). Nevertheless we did see several adult LBBG in the colony, which had P1 shed by April 19. Some notes: the scorse on April 05 2003 were done at Naaktstrand, on preening, bathing and arriving birds, through 20x-60x telescopes. Active moult would be noticed, but to detect arrested moult in such circumstances is pretty difficult. Next year, we try to start our surveys with catching birds and examine the exact primary stage in the inner primaries by taking photographs.

Lesser Black-backed Gull adult, May 09 2014, Katwijk, the Netherlands. Classic graellsii type bird. Complete moult started: P1 growing, P2-P10 old.

Above: 2015. Below: 2014.
Calais port services started to store materials and equipment on the Larus fuscus colony at the quay of the Loire in Calais. Some gulls (like orange OV, ringed the Netherlands and many more birds) are deprived from the location they occupied for so many years.
Already last year, a bulldozer destroyed some nests near the railway. At this location, quay of the Loire at Calais, about 200 Larus fuscus pairs breed (impossible to have a clear idea because of Buddleia grows on the railway).

Tables & Graph

starting date:	30 Apr	07 May	14 May	21 May	28 May	04 Jun
week no:	18	19	20	21	22	23
REM 0	0	0	0	0	0	0
REM 1	0	0	0	0	0	0
REM 2	0	0	0	0	0	0
REM 3	0	0	0	0	0	0
REM 4	0	0	0	0	0	0
REM 5	0	0	0	0	0	0
REM 6	0	0	0	0	0	0
REM 7	0	0	1	0	0	0
REM 8	15	11	21	9	5	3
REM 9	40	34	39	15	12	6
REM 10	466	216	194	85	102	17

n =	521	261	255	109	119	26
average P =	9.9	9.8	9.7	9.7	9.8	9.5
95% CID =	0.04	0.06	0.08	0.12	0.09	0.29
inverse =	1.96	1.97	1.97	1.98	1.98	2.06
Variantie (s²) =	0.17	0.25	0.41	0.38	0.24	0.50
SD (s) =	0.42	0.50	0.64	0.62	0.49	0.71
SE (s_x) =	0.02	0.03	0.04	0.06	0.04	0.14

% class:
0	0	0	0	0	0	0
1	0	0	0	0	0	0
2	0	0	0	0	0	0
3	0	0	0	0	0	0
4	0	0	0	0	0	0
5	0	0	0	0	0	0
6	0	0	0	0	0	0
7	0	0	0	0	0	0
8	3	4	8	8	4	12
9	8	13	15	14	10	23
10	89	83	76	78	86	65

% control:	100	100	100	100	100	100

Table above, data for the Netherlands (2000-2010), results for May (aggregated week): number of remaining old primaries in adults.
REM10 = 10 primaries still old (hence, complete moult not started yet). First signs of complete moult commencement in WEEK 18 (starting 30 April).

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 May (arrested moult excluded). Sample size for this graph is 1291 ringed birds.

starting date:	30 Apr	07 May	14 May	21 May	04 Jun
week no:	18	19	20	21	23
NEW 0	457	205	207	92	8
NEW P1	10	3	10	4	0
NEW P2	3	1	2	0	0
NEW P3	0	0	0	0	0
NEW P4	0	0	0	0	0
NEW P5	0	0	0	0	0
NEW P6	0	0	0	0	0
NEW P7	0	0	0	0	0
NEW P8		0	0	0	0
NEW P9			0	0	0
NEW P10					0

n =	470	209	219	96	8
average NEW P =	0.0	0.0	0.1	0.0	0.0
95% CID =	0.02	0.02	0.04	0.04	0.00
inverse =	1.97	1.97	1.97	1.99	2.36
Variantie (s²) =	0.05	0.03	0.08	0.04	0.00
SD (s) =	0.21	0.18	0.28	0.20	0.00
SE (s_x) =	0.01	0.01	0.02	0.02	0.00

% class
0	97	98	95	96	100
1	2	1	5	4	0
2	1	0	1	0	0
3	0	0	0	0	0
4	0	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 May (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 May (arrested moult excluded). Sample size for this graph is 1002 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).
	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

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 - 11,90

Lesser Black-backed Gull adult, May 08 2016, Nieuw-Haamstede, the Netherlands. Classic graellsii type bird. Complete moult not started: P1-P10 old.

Primary Moult Scores in ringed (near)adult LBBG at Zeebrugge Voorhaven, Belgium in May. Date: 03, 29 & 30 May 2003.
code	ring	RPS	date	code	ring	RPS	date
L-???69	BLB	10	30-mei-03	BLAD	BLUE	10	29-mei-03
L-?0919	BLB	10	03-mei-03	BLAD	BLUE	10	30-mei-03
L-?8648	BLB	10	30-mei-03	BLAH	BLUE	10	03-mei-03
L-39830	BLB	10	30-mei-03	BLAR	BLUE	10	30-mei-03
L-48364	BLB	10	29-mei-03	BMAA	BLUE	10	29-mei-03
L-62174	BLB	10	03-mei-03	BMAF	BLUE	10	30-mei-03
L-62174	BLB	8	30-mei-03	BMAZ	BLUE	10	03-mei-03
L-65126	BLB	10	30-mei-03	BMAZ	BLUE	10	29-mei-03
L-809??	BLB	10	29-mei-03	BMAZ	BLUE	10	30-mei-03
L-80919	BLB	10	30-mei-03	BNAC	BLUE	nn	03-mei-03
L-82???	BLB	10	03-mei-03	BNAH	BLUE	10	03-mei-03
L-82711	BLB	10	30-mei-03	BNAH	BLUE	10	30-mei-03
L-83405	BLB	10	30-mei-03	BNAR	BLUE	10	03-mei-03
L-877??	BLB	10	30-mei-03	BNAR	BLUE	10	29-mei-03
L-89082	BLB	10	03-mei-03	BPAL	BLUE	10	03-mei-03
L-89427	BLB	10	29-mei-03	BTAC	BLUE	10	30-mei-03
L-89465	BLB	10	30-mei-03	BTAF	BLUE	10	30-mei-03
L-89730	BLB	10	03-mei-03	BTAX	BLUE	nn	03-mei-03
L-92064	BLB	10	29-mei-03	BUAH	BLUE	10	03-mei-03
L-92066	BLB	10	29-mei-03	BUAJ	BLUE	10	03-mei-03
L-9281?	BLB	10	30-mei-03	BUAL	BLUE	10	03-mei-03
L-92821	BLB	10	29-mei-03	BUAL	BLUE	10	29-mei-03
L-92873	BLB	10	03-mei-03	BUAL	BLUE	10	30-mei-03
L-92876	BLB	10	03-mei-03	BUAM	BLUE	10	30-mei-03
L-92878	BLB	10	30-mei-03	BVAM	BLUE	nn	03-mei-03
L-95841	BLB	10	30-mei-03	BVAN	BLUE	10	29-mei-03
L-95851	BLB	10	30-mei-03	BVAP	BLUE	10	03-mei-03
L-96064	BLB	10	30-mei-03	BWAD	BLUE	10	03-mei-03
ABAJ	BLUE	10	03-mei-03	BWAD	BLUE	10	29-mei-03
ABAR	BLUE	10	03-mei-03	BWAG	BLUE	nn	29-mei-03
ACAD	BLUE	10	03-mei-03	BWAK	BLUE	10	03-mei-03
ACAD	BLUE	8	29-mei-03	BWAK	BLUE	10	29-mei-03
ACAG	BLUE	10	30-mei-03	BWAK	BLUE	10	30-mei-03
ACAJ	BLUE	10	29-mei-03	BWAY	BLUE	10	03-mei-03
ACAJ	BLUE	10	30-mei-03	xxAH	BLUE	nn	29-mei-03
ACAL	BLUE	10	29-mei-03	GG49806	GBT	10	30-mei-03
ADAF	BLUE	10	29-mei-03	AH6	GREEN	10	03-mei-03
ADAF	BLUE	10	30-mei-03	AH6	GREEN	9	29-mei-03
ADAW	BLUE	nn	30-mei-03	E???	GREEN	10	30-mei-03
AFAF	BLUE	10	29-mei-03	E475	GREEN	10	03-mei-03
AFAP	BLUE	10	03-mei-03	E840	GREEN	nn	03-mei-03
AFAS	BLUE	nn	03-mei-03	EK96	GREEN	10	03-mei-03
AFAS	BLUE	nn	29-mei-03	EK96	GREEN	10	29-mei-03
AGAB	BLUE	10	03-mei-03	EK96	GREEN	10	30-mei-03
AGAB	BLUE	10	29-mei-03	EL07	GREEN	10	30-mei-03
AGAH	BLUE	10	03-mei-03	EM35	GREEN	10	30-mei-03
AHAL	BLUE	10	03-mei-03	NU4	GREEN	10	03-mei-03
AHAP	BLUE	10	29-mei-03	NU4	GREEN	10	30-mei-03
AHAS	BLUE	10	29-mei-03	NV5	GREEN	10	03-mei-03
AHAW	BLUE	10	29-mei-03	NV5	GREEN	10	29-mei-03
AHAZ	BLUE	10	30-mei-03	TJ5	GREEN	10	03-mei-03
AJAJ	BLUE	10	29-mei-03	5.???.???	NLA	10	30-mei-03
AJAY	BLUE	9	30-mei-03	5.330.647	NLA	10	03-mei-03
AMAK	BLUE	10	29-mei-03	5.360.136	NLA	10	03-mei-03
AMAK	BLUE	10	30-mei-03	E037	ORANGE	10	03-mei-03
ANAN	BLUE	10	29-mei-03	E037	ORANGE	10	29-mei-03
ANAS	BLUE	10	30-mei-03	E836	ORANGE	10	03-mei-03
ANAW	BLUE	nn	29-mei-03	E836	ORANGE	nn	29-mei-03
APAH	BLUE	10	03-mei-03	EK47	ORANGE	10	29-mei-03
AUAA	BLUE	10	03-mei-03	ES29	ORANGE	9	30-mei-03
AWAU	BLUE	10	03-mei-03	ES51	ORANGE	10	03-mei-03
AXAG	BLUE	10	03-mei-03	ES98	ORANGE	10	03-mei-03
AZAK	BLUE	nn	30-mei-03	ET03	ORANGE	10	03-mei-03
BAAG	BLUE	9	30-mei-03	ET85	ORANGE	10	30-mei-03
BBAF	BLUE	nn	03-mei-03	EX22	ORANGE	10	03-mei-03
BBAF	BLUE	10	30-mei-03	EX22	ORANGE	nn	29-mei-03
BCAD	BLUE	nn	29-mei-03	EX22	ORANGE	8	30-mei-03
BCAD	BLUE	10	30-mei-03	E131	RED	10	03-mei-03
BDAD	BLUE	10	03-mei-03	RV2	WHITE	nn	03-mei-03
BDAD	BLUE	nn	29-mei-03	RV2	WHITE	10	29-mei-03
BHAW	BLUE	9	30-mei-03	TC5	WHITE	10	30-mei-03
BJAA	BLUE	10	29-mei-03	TP3	WHITE	10	03-mei-03
BKAN	BLUE	10	30-mei-03	TP3	WHITE	9	29-mei-03
				TU7	WHITE	10	03-mei-03
Notes: RPS: Remaining Primary Score: 10 means 10 old primaries, 9 means P1 shed, etc. nn: not noted. BLB: metal ring Bruxelles - Belgium. BLUE: darvic ring blue - Belgium, ringing project Zeebrugge. GREEN: darvic ring green - the Netherlands, ringing project Maasvlakte. NLA: metal ring Arnhem - the Netherlands. ORANGE: darvic ring orange - the Netherlands, ringing project Maasvlakte. RED: darvic ring red - the Netherlands, ringing project Maasvlakte. WHITE: darvic ring white - the Netherlands, ringing project Maasvlakte. May 03 2003: n: 58, (7x not noted, 51x primary score 10) m: primary score 10.0 (all primaries present in 100% of birds) SD: 0.00 May 29 2003: n: 42, (8x not noted, 31x primary score 10, 2x score 9, 1x score 8) m: primary score 9.9 SD: 0.41 May 30 2003: n: 52, (3x not noted, 43 primary score 10, 4x score 9, 2x score 8) m: primary score 9.8 SD: 0.47 Conclusions: When primary score was not noted (nn), but recorded 10 at a later date, nn can be replaced for 10.

Primary Moult Scores in ringed (near)adult LBBG at Maasvlakte & Dintelhaven, the Netherlands in May. Date: 07, 17, 27 May & 02 June 2003.

code ring RPS date code ring RPS date

?-?8360 BLB 10 05-07-03 TS0 green 10 05-17-03

?-?9951 BLB 10 06-02-03 TS0 green 10 05-27-03

L-89??? BLB 10 05-07-03 TS1 green 10 05-07-03

L-93303 BLB 10 05-07-03 UA4 green 10 05-07-03

L-93303 BLB 10 05-17-03 UT8 green 10 05-17-03

FA8370? GBT 10 06-02-03 UT8 green 10 05-27-03

GG44883 GBT 10 05-07-03 EJ86 green 10 05-07-03

GG93433 GBT nn 06-02-03 JL7 green 10 05-07-03

GT75716 GBT 10 06-02-03 5.251.194 NLA 10 06-02-03

E129 green 10 05-27-03 5.257.218 NLA 10 06-02-03

E277 green 10 05-17-03 5.257.580 NLA 10 06-02-03

E392 green nn 06-02-03 5.321.306 NLA 10 05-27-03

E496 green 10 05-17-03 5.360.522 NLA 10 05-17-03

E610 green 10 05-07-03 5.360.522 NLA 10 05-27-03

E610 green 10 05-17-03 ?.???.199 NLA 10 05-07-03

E610 green 10 06-02-03 5.308.77? NLA 10 05-07-03

E623 green 10 05-07-03 5.360.??? NLA 10 05-17-03

E641 green 10 05-07-03 NY0 nn 10 05-17-03

E835 green 10 05-27-03 AM0 orange 10 06-02-03

E968 green 10 05-07-03 CT7 orange 10 06-02-03

E994 green 10 05-07-03 CU9 orange 9 05-07-03

EAK5 green 10 05-07-03 CU9 orange 8 05-27-03

EAS1 green 10 05-07-03 CU9 orange 8 06-02-03

EAS1 green 10 05-17-03 E017 orange nn 06-02-03

EAS1 green 9 06-02-03 E053 orange nn 05-07-03

ECC0 green 10 05-17-03 E053 orange 10 06-02-03

ECC3 green nn 06-02-03 E202 orange 10 05-17-03

EE02 green 10 05-07-03 E264 orange 10 05-17-03

EE44 green 10 05-27-03 E400 orange nn 05-07-03

EH89 green 10 05-07-03 E600 orange 8 06-02-03

EJ1 green 10 06-02-03 E702 orange 10 05-17-03

EJ15 green 10 05-07-03 E818 orange 10 05-17-03

EJ97 green 10 05-07-03 E835 orange 10 05-17-03

EJ97 green 10 05-17-03 E835 orange 9 05-27-03

EL4 green 9 06-02-03 EC40 orange 10 05-17-03

EN40 green 10 05-17-03 EC40 orange 10 06-02-03

EN84 green 10 05-17-03 EC57 orange 10 06-02-03

EP79 green 10 05-17-03 ECC1 orange 10 05-07-03

ES98 green 10 05-17-03 EH42 orange 10 05-07-03

ES98 green 10 06-02-03 EH52 orange 10 05-17-03

ET17 green 9 05-17-03 EH79 orange nn 05-07-03

ET79 green 10 05-07-03 EH79 orange 10 06-02-03

EV39 green 10 05-17-03 EK85 orange 10 05-07-03

EV39 green 9 06-02-03 EK85 orange 10 06-02-03

EV60 green 10 05-07-03 EL83 orange 10 05-07-03

EY16 green 10 05-07-03 EL83 orange 10 05-07-03

EY17 green 10 05-17-03 EL83 orange 10 05-27-03

EY23 green 10 05-17-03 EM30 orange 10 06-02-03

JH5 green 10 05-07-03 EM41 orange 10 05-17-03

JH5 green 10 05-17-03 EM86 orange 10 06-02-03

JH5 green 10 06-02-03 EN24 orange 10 05-17-03

JL7 green 10 05-07-03 EN54 orange 10 05-27-03

JL7 green 10 05-17-03 EN84 orange 10 06-02-03

KJ0 green 10 05-07-03 EP23 orange 9 06-02-03

KM79? green 9 06-02-03 EP94 orange 10 06-02-03

KV4 green 10 05-07-03 ES43 orange 10 05-17-03

ML9 green 10 05-07-03 EU77 orange nn 06-02-03

NH0 green 10 05-17-03 EU95 orange 10 06-02-03

NV4 green 10 05-07-03 EV62 orange 10 05-17-03

NV7 green 10 05-07-03 EY77 orange 10 05-07-03

PL9 green 10 05-07-03 KE8 orange 10 05-07-03

PL9 green 10 05-17-03 KJ0 orange 10 06-02-03

PP0 green 9 06-02-03 ML2 orange 10 05-27-03

PP4 green 10 05-07-03 UL0 orange 10 06-02-03

PP4 green 10 05-07-03 NP8 orange (wh) 10 05-07-03

PP4 green 10 06-02-03 NP8 orange (wh) 10 06-02-03

PR4 green 10 05-07-03 PS6 orange (wh) 10 05-27-03

PR4 green 10 05-17-03 E319 red 10 05-17-03

PS0 green 10 06-02-03 E349 red 10 05-27-03

PV2 green 10 05-17-03 3 LINES white 10 05-07-03

RC3 green 10 05-07-03 R18 white 10 05-07-03

RL9 green 10 05-07-03 RR5 white 10 05-17-03

RV0 green 10 05-17-03 SH2 white 10 05-07-03

SH2 green nn 05-17-03 SS3 white 10 05-07-03

TH1 green 10 05-17-03 TN4 white 10 05-07-03

TH5 green 10 05-17-03 7 S white red 10 05-07-03

7 S white red 10 05-07-03

Notes:
RPS: Remaining Primary Score: 10 means 10 old primaries, 9 means P1 shed, etc.
nn: not noted.
BLB: metal ring Bruxelles - Belgium.
GBT: metal ring BTO - Britain.
GREEN: darvic ring green - the Netherlands, ringing project Maasvlakte.
NLA: metal ring Arnhem - the Netherlands.
ORANGE: darvic ring orange - the Netherlands, ringing project Maasvlakte.
RED: darvic ring red - the Netherlands, ringing project Maasvlakte.
WHITE: darvic ring white - the Netherlands, ringing project Maasvlakte.
May 05 2003:
n: 56, (3x not noted, 52x primary score 10, 3x score 9)
m: primary score 10.0
SD: 0.14
May 17 2003:
n: 43, (1x not noted, 41x primary score 10, 1x score 9)
m: primary score 10.0
SD: 0.15
May 27 2003:
n: 14, (3x not noted, 12 primary score 10, 1x score 9, 1x score 8)
m: primary score 9.8
SD: 0.58
June 02 2003:
n: 35, (5x not noted, 27 primary score 10, 6x score 9, 2x score 8)
m: primary score 9.7
SD: 0.57

Conclusions:
When primary score was not noted (nn), but recorded 10 at a later date, nn can be replaced for 10.

LBBG from Norway: intermedius

LBBG intermedius J0K0 1CY-6CY, August 2008 - May 2013, Norway - Denmark - Spain - Morocco - the Netherlands.
Nice example bird showing arrested moult in 3CY after an extraordinary extensive moult at the wintering grounds in Morocco. Supported by images.

LBBG from England: graellsii

Lesser Black-backed Gull 6cy, 9cy, 10cy RXB May 2013, Calais, NW France. Picture: Jean-Michel Sauvage. Also as 5CY & 10CY.

Lesser Black-backed Gull 19cy & 21cy BTO GG49760 April-May 2012 & April 2014, Calais, NW France. Picture: Jean-Michel Sauvage.

LBBG adult BTO GG-63075, May 31 2002, EMO, Maasvlakte, the Netherlands (51.59N,04.02E). A female begging for food at a male and still without a nest.

LBBG adult BTO GG-81065, May 03 2004, EMO, Maasvlakte, the Netherlands (51.59N,04.02E). A female with a nest.

LBBG adult BTO G?-09708, May 03 2004, EMO, Maasvlakte, the Netherlands (51.59N,04.02E). A female with a nest.

Lesser Black-backed Gull graellsii BTO FP778xx adult, May 02 2017, Hoornderslag - Texel, the Netherlands.

Lesser Black-backed Gull BTO FV38253 8CY-12CY, June 2013, April 2014 & May 2017, Calais, NW France. Picture: Jean-Michel Sauvage.

LBBG from France: graellsii

Lesser Black-backed Gull 5cy 029A April, May & July 2013, Calais, NW France. Picture: Jean-Michel Sauvage.

Lesser Black-backed Gull graellsii EA 639805 / 104N 8cy, May 02 2015, Calais, NW France. Picture: Jean-Michel Sauvage.

Lesser Black-backed Gull graellsii EA 639806 / 105N 10CY & 13CY, April 2014 & May 2017, Calais, NW France. Picture: Jean-Michel Sauvage.

Lesser Black-backed Gull graellsii FRP EA670038 / 154N 7cy-8cy & 13cy, April 2011, April 2012 & May 2017, Calais, NW France. Picture: Jean-Michel Sauvage.

Lesser Black-backed Gull FRP EA639885 / 165N 7CY-11CY, 2011-2015, Calais, NW France. Picture: Jean-Michel Sauvage.

Lesser Black-backed Gull 6cy 255K May-June 2013, Calais, NW France. Picture: Jean-Michel Sauvage.

Lesser Black-backed Gull 8cy 399N April, May & June 2013, Calais, NW France. Picture: Jean-Michel Sauvage.

Lesser Black-backed Gull 7cy FRP EA670077 / 404N May 04 2012, Calais, NW France. Picture: Jean-Michel Sauvage.

Lesser Black-backed Gull 7cy FRP EA672138 / 409N May 04 2012, Calais, NW France. Picture: Jean-Michel Sauvage.

Lesser Black-backed Gull graellsii EA 672341 / 440N 7CY & 9CY, April - May 2013 & May 2015, Calais, NW France. Picture: Jean-Michel Sauvage.

Lesser Black-backed Gull 5cy 452N May 19 2011, Calais, NW France. Picture: Jean-Michel Sauvage.

Lesser Black-backed Gull graellsii FRP EA672243 / 530N 7CY-11Y, April 2013 & 2014 & May 2017, Calais, NW France. Picture: Jean-Michel Sauvage.

Lesser Black-backed Gull graellsii FRP EA672380 / 593N 11CY, May - July 2017, Calais, NW France. Picture: Jean-Michel Sauvage.

Lesser Black-backed Gull adult 689N May 11 2013, Calais, NW France. Picture: Jean-Michel Sauvage.

Lesser Black-backed Gull graellsii 702N 10CY May 06 2017, Calais, NW France. Picture: Jean-Michel Sauvage.

Lesser Black-backed Gull graellsii FRP EA672544 / 738N 5cy-10cy, April 2012 - May 2017, Calais, NW France. Picture: Jean-Michel Sauvage.

Lesser Black-backed Gull graellsii 804N 8CY-10CY, April 2015 & May 2017, Calais, NW France. Picture: Jean-Michel Sauvage.

Lesser Black-backed Gull graellsii 918N 5CY-8CY, March 2013 - April 2016, Calais, NW France. Picture: Jean-Michel Sauvage.

Lesser Black-backed Gull graellsii FRP EA558211 adult, May 14 2017, Calais, NW France. Picture: Jean-Michel Sauvage.

Lesser Black-backed Gull graellsii FRP EA558245 adult, May 14 2017, Calais, NW France. Picture: Jean-Michel Sauvage.

Lesser Black-backed Gull adult FRP EA677791 April, May & June 2013, Calais, NW France. Picture: Jean-Michel Sauvage.

Lesser Black-backed Gull graellsii FRP EA672456 / 937K adult, May - July 2017, Calais, NW France. Picture: Jean-Michel Sauvage.

Lesser Black-backed Gull graellsii FRP EA677789 adult, May 06 2017, Calais, NW France. Picture: Jean-Michel Sauvage.

LBBG from Belgium: graellsii

LBBG 5cy ACAJ May 29 2003, Voorhaven, Zeebrugge, Belgium (51.59N,04.02E). Ringed at Zeebrugge as pullus.

LBBG 6cy ACAL May 29 2003, Voorhaven, Zeebrugge, Belgium (51.59N,04.02E). Ringed at Zeebrugge as 2cy.

LBBG 5cy ADAF May 29 2003, Voorhaven, Zeebrugge, Belgium (51.59N,04.02E). Ringed at Zeebrugge as pullus.

LBBG 6cy AFAF May 29 2003, Voorhaven, Zeebrugge, Belgium (51.59N,04.02E). Ringed at Zeebrugge as 2cy.

LBBG 5cy AFAS May 03 2003, Voorhaven, Zeebrugge, Belgium (51.59N,04.02E). Ringed at Zeebrugge as pullus.

LBBG 8cy AGAB May 03 2003, Voorhaven, Zeebrugge, Belgium (51.59N,04.02E). Ringed at Zeebrugge as 4cy.

LBBG 5cy AHAS May 29 2003, Voorhaven, Zeebrugge, Belgium (51.59N,04.02E). Ringed at Zeebrugge as pullus.

LBBG 7cy AHAW & E840 May 03 2003, Voorhaven, Zeebrugge, Belgium (51.59N,04.02E). Ringed at Zeebrugge as 3cy.

LBBG 5cy AMAK May 29 2003, Voorhaven, Zeebrugge, Belgium (51.59N,04.02E). Ringed at Zeebrugge as pullus.

LBBG 6cy BDAD May 03 2003, Voorhaven, Zeebrugge, Belgium (51.59N,04.02E). Ringed at Zeebrugge as 2cy.

LBBG 6cy BJAA May 29 2003, Voorhaven, Zeebrugge, Belgium (51.59N,04.02E). Ringed at Zeebrugge as 2cy.

LBBG 7cy BLAD May 29 2003, Voorhaven, Zeebrugge, Belgium (51.59N,04.02E). Ringed at Zeebrugge as 3cy.

LBBG 7cy BMAA May 29 2003, Voorhaven, Zeebrugge, Belgium (51.59N,04.02E). Ringed at Zeebrugge as 3cy.

LBBG 7cy BMAZ May 29 2003, Voorhaven, Zeebrugge, Belgium (51.59N,04.02E). Ringed at Zeebrugge as 3cy.

LBBG 7+cy BWAD May 03 2003, Voorhaven, Zeebrugge, Belgium (51.59N,04.02E). Ringed at Zeebrugge as adult.

Lesser Black-backed Gull graellsii DL.AS 11CY, May 05 2016, Neeltje Jans, the Netherlands (51°38'17.74"N 3°42'27.05"E).

Lesser Black-backed Gull graellsii D.UAK 2CY & 10CY, September 2007 & April - May 2015, the Netherlands. Picture: Merijn Loeve & Pim Wolf.

Lesser Black-backed Gull graellsii GHAC adult, May 30 2015, Calais, NW France. Picture: Jean-Michel Sauvage.

Lesser Black-backed Gull graellsii HAAB 11CY, May - June 2016, Maasvlakte (Amazonehaven), the Netherlands (51.56 N 04.03 E).

LBBG 5cy-6cy HKAB 2012-2013, Calais, NW France. Picture: Jean-Michel Sauvage.

Lesser Black-backed Gull graellsii HRAS 4CY & 8CY, May 2011 & May 2015, Belgium & the Netherlands. Picture: Peter Adriaens & Merijn Loeve.

Lesser Black-backed Gull graellsii KJAM 7CY-11CY, 2013-2017, Calais, NW France. Picture: Jean-Michel Sauvage.

LBBG 7cy KJAP May 04 2013, Calais, NW France. Picture: Jean-Michel Sauvage.

Lesser Black-backed Gull graellsii L.KAR 6CY, May 01 2014, Maasvlakte, the Netherlands. Picture: Merijn Loeve.

LBBG 5cy LRAU April & May 2013, Calais, NW France. Picture: Jean-Michel Sauvage.

Lesser Black-backed Gull graellsii MYAL 8CY, May 11 2016, Maasvlakte (Amazonehaven), the Netherlands (51.56 N 04.03 E).

Lesser Black-backed Gull graellsii NHAH 4CY-6CY, July 2013, April 2014, May 2015, Calais, NW France. Picture: Jean-Michel Sauvage.

LBBG 7cy L-62174 , May 03 & 30 2003, Voorhaven, Zeebrugge, Belgium (51.59N 04.02E).

LBBG 5cy L-89427 , May 29 2003, Voorhaven, Zeebrugge, Belgium (51.59N,04.02E). No mirror on P10.

Lesser Black-backed Gull BLB L904293 adult, May 04 2015, Calais, NW France. Picture: Jean-Michel Sauvage.

Lesser Black-backed Gull graellsii BLB L906775 6-11CY, April 2012 - May 2017, Calais, NW France. Picture: Jean-Michel Sauvage.

Lesser Black-backed Gull graellsii BLB L-913126 6CY-8CY, May 2015 & 2017, Calais, NW France. Picture: Jean-Michel Sauvage.

Lesser Black-backed Gull graellsii BLB L106388 10CY-13CY, 2012-2015, Calais, NW France. Picture: Jean-Michel Sauvage.

LBBG adult BLB L906131 April-May 2013, Calais, NW France. Picture: Jean-Michel Sauvage.

Lesser Black-backed Gull 6CY-12CY BLB L906179 2010-2016, Calais, NW France. Picture: Jean-Michel Sauvage.

Lesser Black-backed Gull graellsii BLB L906607 9CY, May 01 2014, Boulogne sur Mer, NW France. Picture: Jean-Michel Sauvage.

Lesser Black-backed Gull graellsii BLB L-913126 adult, May 30 2015, Calais, NW France. Picture: Jean-Michel Sauvage.

Lesser Black-backed Gull graellsii BLB L-915715 6CY, May 11 2016, Maasvlakte (Amazonehaven), the Netherlands (51.56 N 04.03 E).

LBBG from the Netherlands: Dutch intergrade graellsii

Lesser Black-backed Gull graellsii 5.G 5CY, May 11 2016, Europoort (Dintelhaven), the Netherlands (51.57 N 04.06 E).

Lesser Black-backed Gull graellsii C1 adult, May 11 2016, Europoort (Dintelhaven), the Netherlands (51.57 N 04.06 E).

Lesser Black-backed Gull graellsii C3 adult, May-June 2015 & May 2016, Europoort (Dintelhaven), the Netherlands (51.57 N 04.06 E). Picture: Merijn Loeve & Mars Muusse.

Lesser Black-backed Gull graellsii C6 adult, May 21 2015, Maasvlakte - Europoort, the Netherlands. Picture: Merijn Loeve.

Lesser Black-backed Gull graellsii C8 adult, May 11 2016, Europoort (Dintelhaven), the Netherlands (51.57 N 04.06 E).

Lesser Black-backed Gull graellsii CZ adult, May 11 2016, Europoort (Dintelhaven), the Netherlands (51.57 N 04.06 E).

Lesser Black-backed Gull graellsii HF adult, May 11 2016, Europoort (Dintelhaven), the Netherlands (51.57 N 04.06 E).

Lesser Black-backed Gull graellsii H.V 5CY, May 11 2016, Europoort (Dintelhaven), the Netherlands (51.57 N 04.06 E).

Lesser Black-backed Gull graellsii J.E 4CY-5CY, June 2015 & May 2016, Europoort (Dintelhaven), the Netherlands (51.57 N 04.06 E). Picture: Merijn Loeve & Mars Muusse.

Lesser Black-backed Gull graellsii K9 adult, May 11 2016, Europoort (Dintelhaven), the Netherlands (51.57 N 04.06 E).

Lesser Black-backed Gull graellsii KB adult, May 11 2016, Europoort (Dintelhaven), the Netherlands (51.57 N 04.06 E).

Lesser Black-backed Gull graellsii KG adult, May 11 2016, Europoort (Dintelhaven), the Netherlands (51.57 N 04.06 E).

Lesser Black-backed Gull graellsii KH adult, May 11 2016, Europoort (Dintelhaven), the Netherlands (51.57 N 04.06 E).

Lesser Black-backed Gull graellsii KJ adult, May 11 2016, Europoort (Dintelhaven), the Netherlands (51.57 N 04.06 E).

Lesser Black-backed Gull graellsii KL adult, May 11 2016, Europoort (Dintelhaven), the Netherlands (51.57 N 04.06 E).

Lesser Black-backed Gull graellsii KM adult, May 11 2016, Europoort (Dintelhaven), the Netherlands (51.57 N 04.06 E).

Lesser Black-backed Gull graellsii KN adult, May 11 2016, Europoort (Dintelhaven), the Netherlands (51.57 N 04.06 E).

Lesser Black-backed Gull graellsii K= adult, May 11 2016, Europoort (Dintelhaven), the Netherlands (51.57 N 04.06 E).

Lesser Black-backed Gull graellsii MB adult, May 11 2016, Europoort (Dintelhaven), the Netherlands (51.57 N 04.06 E).

Lesser Black-backed Gull graellsii MD adult, May 11 2016, Europoort (Dintelhaven), the Netherlands (51.57 N 04.06 E).

Lesser Black-backed Gull graellsii NB adult, May 29 2015, Katwijk, the Netherlands. Picture: Merijn Loeve & ringing team Roland-Jan Buijs.

Lesser Black-backed Gull graellsii NC adult, May 29 2015, Katwijk, the Netherlands. Picture: Merijn Loeve & ringing team Roland-Jan Buijs.

Lesser Black-backed Gull graellsii ND adult, May 2015 & May 2016, Katwijk-Noordwijk, the Netherlands. Picture: Merijn Loeve & Mars Muusse.

Lesser Black-backed Gull graellsii NE adult, May 29 2015, Katwijk, the Netherlands. Picture: Merijn Loeve & ringing team Roland-Jan Buijs.

Lesser Black-backed Gull graellsii NF adult, May 29 2015, Katwijk, the Netherlands. Picture: Merijn Loeve & ringing team Roland-Jan Buijs.

Lesser Black-backed Gull graellsii NG adult, May 29 2015, Katwijk, the Netherlands. Picture: Merijn Loeve & ringing team Roland-Jan Buijs.

Lesser Black-backed Gull graellsii NK adult, May 29 2015, Katwijk, the Netherlands. Picture: Merijn Loeve & ringing team Roland-Jan Buijs.

Lesser Black-backed Gull graellsii NL adult, May 29 2015, Katwijk, the Netherlands. Picture: Merijn Loeve & ringing team Roland-Jan Buijs.

Lesser Black-backed Gull graellsii NM adult, May 29 2015, Katwijk, the Netherlands. Picture: Merijn Loeve & ringing team Roland-Jan Buijs.

Lesser Black-backed Gull graellsii NN adult, May 29 2015, Katwijk, the Netherlands. Picture: Merijn Loeve & ringing team Roland-Jan Buijs.

Lesser Black-backed Gull graellsii NP adult, May 29 2015, Katwijk, the Netherlands. Picture: Merijn Loeve & ringing team Roland-Jan Buijs.

Lesser Black-backed Gull graellsii NR adult, May 29 2015, Katwijk, the Netherlands. Picture: Merijn Loeve & ringing team Roland-Jan Buijs.

Lesser Black-backed Gull graellsii NT adult, May 29 2015, Katwijk, the Netherlands. Picture: Merijn Loeve & ringing team Roland-Jan Buijs.

Lesser Black-backed Gull graellsii NU adult, May 29 2015, Katwijk, the Netherlands. Picture: Merijn Loeve & ringing team Roland-Jan Buijs.

Lesser Black-backed Gull graellsii NV sub-adult, May 29 2015, Katwijk, the Netherlands. Picture: Merijn Loeve & ringing team Roland-Jan Buijs.

Lesser Black-backed Gull graellsii NW adult, May 29 2015, Katwijk, the Netherlands. Picture: Merijn Loeve & ringing team Roland-Jan Buijs.

Lesser Black-backed Gull graellsii NX sub-adult, May 29 2015, Katwijk, the Netherlands. Picture: Merijn Loeve & ringing team Roland-Jan Buijs.

Lesser Black-backed Gull graellsii R8 6CY, May 04 2015, Rotterdam, the Netherlands. Picture: Merijn Loeve.

Lesser Black-backed Gull graellsii R.B 5CY, May 11 2016, Europoort (Dintelhaven), the Netherlands (51.57 N 04.06 E).

Lesser Black-backed Gull graellsii Z.8 5CY, May 11 2016, Maasvlakte (Amazonehaven), the Netherlands (51.56 N 04.03 E).

Lesser Black-backed Gull graellsii 52 5CY, May 23 2014, Maasvlakte, the Netherlands. Picture: Merijn Loeve.

Lesser Black-backed Gull graellsii NY 6CY, May 13 2014, Sassenplaat, the Netherlands. Picture: Merijn Loeve.

Lesser Black-backed Gull graellsii N+ adult, May 01 2015, Maasvlakte, the Netherlands. Picture: Merijn Loeve.

Lesser Black-backed Gull graellsii P* adult, May 01 2014, Maasvlakte, the Netherlands. Picture: Merijn Loeve.

Lesser Black-backed Gull graellsii R= adult, March & May 2015, Maasvlakte, the Netherlands. Picture: Merijn Loeve.

Lesser Black-backed Gull graellsii U7 5CY, May & July 2015, Rotterdam, the Netherlands. Picture: Merijn Loeve.

Lesser Black-backed Gull graellsii U= was EL03 21CY, May 11 2016, Europoort (Dintelhaven), the Netherlands (51.57.00 N 04.06.00 E).

Lesser Black-backed Gull graellsii Z= was PM4 20CY, May 11 2016, Europoort (Dintelhaven), the Netherlands (51.57.00 N 04.06.00 E).

possible Lesser Black-backed Gull graellsii x Herring Gull argenteus KB adult, May 28 2013, Katwijk, the Netherlands. Picture: Jeroen Nagtegaal & ringing team Roland-Jan Buijs.

Lesser Black-backed Gull graellsii P.V 5CY, May 14 2017, Katwijk, the Netherlands.

Lesser Black-backed Gull graellsii TD adult, May 11 2016, Europoort (Dintelhaven), the Netherlands (51.57.00 N 04.06.00 E).

Lesser Black-backed Gull graellsii 0.0 5CY, May 11 2016, Europoort (Dintelhaven), the Netherlands (51.57.00 N 04.06.00 E).

Lesser Black-backed Gull graellsii 2.B 6CY, May 11 2016, Europoort (Dintelhaven), the Netherlands (51.57.00 N 04.06.00 E).

Lesser Black-backed Gull graellsii 9.9 was C88 14CY, May 11 2016, Europoort (Dintelhaven), the Netherlands (51.57 N 04.06 E).

Lesser Black-backed Gull graellsii 4+ 15CY, May 11 2016, Europoort (Dintelhaven), the Netherlands (51.57 N 04.06 E).

Lesser Black-backed Gull graellsii 58 adult, May 11 2016, Maasvlakte (Amazonehaven), the Netherlands (51.56 N 04.03 E).

Lesser Black-backed Gull graellsii 5* adult, May 11 2016, Maasvlakte (Amazonehaven), the Netherlands (51.56 N 04.03 E).

Lesser Black-backed Gull graellsii 6F adult, May 11 2016, Maasvlakte (Amazonehaven), the Netherlands (51.56 N 04.03 E).

Lesser Black-backed Gull graellsii 8W adult, May 11 2016, Europoort (Dintelhaven), the Netherlands (51.57 N 04.06 E).

Lesser Black-backed Gull graellsii 8X adult, May 11 2016, Europoort (Dintelhaven), the Netherlands (51.57 N 04.06 E).

Lesser Black-backed Gull graellsii 9X adult, May 11 2016, Europoort (Dintelhaven), the Netherlands (51.57 N 04.06 E).

Lesser Black-backed Gull graellsii M9 adult, May 11 2016, Maasvlakte (Amazonehaven), the Netherlands (51.56.00 N 04.03.00 E).

Lesser Black-backed Gull graellsii M+ 20CY, May 11 2016, Maasvlakte (Amazonehaven), the Netherlands (51.56.00 N 04.03.00 E).

Lesser Black-backed Gull graellsii NB adult, May 11 2016, Maasvlakte (Amazonehaven), the Netherlands (51.56.00 N 04.03.00 E).

Lesser Black-backed Gull graellsii NE adult, August 2014 & May-June 2016, Boulogne sur mer, NW France & Maasvlakte, the Netherlands. Picture: Jean-Michel Sauvage & Mars Muusse.

Lesser Black-backed Gull graellsii M9 adult, May 11 2016, Maasvlakte (Amazonehaven), the Netherlands (51.56.00 N 04.03.00 E).

Lesser Black-backed Gull graellsii Y6 adult, May 11 2016, Maasvlakte (Coloradoweg), the Netherlands (51.57.00 N 04.01.00 E).

Lesser Black-backed Gull graellsii Z2 adult, May 11 2016, Maasvlakte (Coloradoweg), the Netherlands (51.57 N 04.01 E).

Lesser Black-backed Gull graellsii ZF adult, May 11 2016, Maasvlakte (Amazonehaven), the Netherlands (51.56 N 04.03 E).

Lesser Black-backed Gull graellsii ZR adult, May 11 2016, Maasvlakte (Amazonehaven), the Netherlands (51.56 N 04.03 E).

Lesser Black-backed Gull graellsii ZV adult, May 11 2016, Maasvlakte (Amazonehaven), the Netherlands (51.56 N 04.03 E).

Lesser Black-backed Gull graellsii H5 adult, May 2006, October 2011 & August 2016, the Netherlands. Picture: Theo Muusse, Maarten van Kleinwee & Henri Zomer.

Lesser Black-backed Gull graellsii JV4T adult, May 02-23 2015, Maasvlakte - Europoort, the Netherlands. Picture: Merijn Loeve.

Lesser Black-backed Gull graellsii PB6T adult, March 28 & May 02 2014, Maasvlakte, the Netherlands. Picture: Merijn Loeve.

Lesser Black-backed Gull graellsii PJ7T adult, May 01 2014, Maasvlakte, the Netherlands. Picture: Merijn Loeve.

Lesser Black-backed Gull graellsii RL1T adult, May 23 2014, Maasvlakte, the Netherlands. Picture: Merijn Loeve.

Lesser Black-backed Gull graellsii T061 adult, May 01 2014 & April 07 2015, Maasvlakte, the Netherlands. Picture: Merijn Loeve.

Lesser Black-backed Gull graellsii 27 adult, May 2006 & April 2014, Moerdijk & Sassenplaat, the Netherlands. Picture: Merijn Loeve & Mars Muusse.

Lesser Black-backed Gull graellsii 69 adult, May 2006 & April 2015, Moerdijk, the Netherlands. Picture: Merijn Loeve & Mars Muusse.

Lesser Black-backed Gull graellsii C6 adult, May 2006 & April 2015, Moerdijk, the Netherlands. Picture: Merijn Loeve & Mars Muusse.

Lesser Black-backed Gull graellsii JH adult, May 2005 & March 2014, Moerdijk & Sassenplaat, the Netherlands. Picture: Merijn Loeve & Mars Muusse.

Lesser Black-backed Gull graellsii K6 adult, May 2005 & May 2014, Moerdijk & Sassenplaat, the Netherlands. Picture: Merijn Loeve & Mars Muusse.

Lesser Black-backed Gull graellsii KP adult, May 2005, May 2006 & September 2012, Moerdijk & Dordrecht, the Netherlands. Picture: Merijn Loeve & Mars Muusse.

Lesser Black-backed Gull 6cy-9cy OV 2010-2014, Calais, NW France. Picture: Jean-Michel Sauvage.

Lesser Black-backed Gull graellsii SF adult, May 01 & August 10 2014, Maasvlakte, the Netherlands. Picture: Merijn Loeve.

Lesser Black-backed Gull graellsii T6 adult, May 2005, April 2014, Moerdijk & Sassenplaat, the Netherlands. Picture: Merijn Loeve & Mars Muusse.

Lesser Black-backed Gull graellsii 1S 4CY & 12CY, May 2006 & May 2014, Moerdijk-Sassenplaat, the Netherlands. Picture: Merijn Loeve & Roland-Jan Buijs.

Lesser Black-backed Gull graellsii BA 4CY & 12CY, May 2006 & March 2014, Moerdijk-Sassenplaat, the Netherlands. Picture: Merijn Loeve & Mars Muusse.

LBBG 5cy D0 May 05 2011, IJmuiden, the Netherlands.

Lesser Black-backed Gull graellsii DJ 8CY-9CY, May 2014 & July 2015, Maasvlakte & Utrecht, the Netherlands. Picture: Merijn Loeve & Herman Bouman.

Lesser Black-backed Gull graellsii F4 8CY, May 13 2014, Sassenplaat, the Netherlands. Picture: Merijn Loeve.

Lesser Black-backed Gull graellsii JH (was SX7) 9CY & 17CY, May 2006 & February 2014, Moerdijk, the Netherlands. Picture: Merijn Loeve & Mars Muusse.

Lesser Black-backed Gull graellsii NL (was EAU7) 10CY & 18CY, May 2006 & March 2014, Moerdijk, the Netherlands. Picture: Merijn Loeve & Mars Muusse.

Lesser Black-backed Gull graellsii S3 adult, May 13 2014, Sassenplaat, the Netherlands. Picture: Merijn Loeve.

Lesser Black-backed Gull graellsii 79 adult, 2005, 2013 & 2014, Dordrecht & Moerdijk, the Netherlands. Picture: Merijn Loeve & Muusse brothers.

Lesser Black-backed Gull graellsii HV adult, May 2005 & May 2014, Moerdijk & Sassenplaat, the Netherlands. Picture: Merijn Loeve & Mars Muusse.

Lesser Black-backed Gull graellsii NN adult, May 2006 & July 2015, Moerdijk & Tilburg, the Netherlands. Picture: Merijn Loeve & Mars Muusse.

Lesser Black-backed Gull graellsii B.3 adult, March - April 2015, May 2016, Europoort (Dintelhaven), the Netherlands (51.57.00 N 04.06.00 E). Picture: Merijn Loeve & Mars Muusse.

Lesser Black-backed Gull graellsii B7 adult, May 01 2015, Maasvlakte - Europoort, the Netherlands. Picture: Merijn Loeve.

Lesser Black-backed Gull graellsii B.8 adult, June 08 2015 & May 11 2016, Europoort (Dintelhaven), the Netherlands (51.57 N 04.06 E). Picture: Merijn Loeve & Mars Muusse.

Lesser Black-backed Gull graellsii B.F adult, March 30 2015 & May 11 2016, Europoort (Dintelhaven), the Netherlands (51.57 N 04.06 E). Picture: Merijn Loeve & Mars Muusse.

Lesser Black-backed Gull graellsii BH adult, May 01 2015, Maasvlakte - Europoort, the Netherlands. Picture: Merijn Loeve.

Lesser Black-backed Gull graellsii B.M adult, May 11 2016, Europoort (Dintelhaven), the Netherlands (51.57 N 04.06 E).

Lesser Black-backed Gull graellsii B.X adult, April - June 2015 & May 2016, Europoort (Dintelhaven), the Netherlands (51.57 N 04.06 E). Picture: Merijn Loeve & Mars Muusse.

Lesser Black-backed Gull graellsii BZ adult, March 30 & May 21 2015, Maasvlakte - Europoort, the Netherlands. Picture: Merijn Loeve.

Lesser Black-backed Gull graellsii C.E adult, May 11 2016, Europoort (Dintelhaven), the Netherlands (51.57 N 04.06 E).

Lesser Black-backed Gull graellsii D7 adult, May 01 2015, Maasvlakte - Europoort, the Netherlands. Picture: Merijn Loeve.

Lesser Black-backed Gull graellsii DX adult, May 02 2014, Maasvlakte - Europoort, the Netherlands. Picture: Merijn Loeve.

Lesser Black-backed Gull graellsii DZ adult, May 02 2014, Maasvlakte - Europoort, the Netherlands. Picture: Merijn Loeve.

Lesser Black-backed Gull graellsii EA (formerly EY98) 18CY, May 23 & June 02 2014, Maasvlakte, the Netherlands. Picture: Merijn Loeve.

Lesser Black-backed Gull graellsii EB (formerly EA57) 19CY, May 23 2014, Maasvlakte, the Netherlands. Picture: Merijn Loeve.

Lesser Black-backed Gull graellsii E.D was EJ34 21CY, May 11 2016, Maasvlakte (Amazonehaven), the Netherlands (51.56 N 04.03 E).

Lesser Black-backed Gull graellsii E.T adult, May 11 2016, Maasvlakte (Amazonehaven), the Netherlands (51.56 N 04.03 E).

Lesser Black-backed Gull graellsii GL adult, May 30 2015, Maasvlakte - Europoort, the Netherlands. Picture: Merijn Loeve.

Lesser Black-backed Gull graellsii 18 7CY, May 01 2014, Sassenplaat, the Netherlands. Picture: Merijn Loeve.

LBBG ad YAAS May 06 2011, IJmuiden, the Netherlands.

Lesser Black-backed Gull graellsii Y.ABU adult, May 29 2017, Heemskerk, the Netherlands.

Lesser Black-backed Gull graellsii YANL 5CY, May 13 2014, Sassenplaat, the Netherlands. Picture: Merijn Loeve.

Lesser Black-backed Gull graellsii M.AXW adult, May 02 2017, Den Hoorn - Texel, the Netherlands.

Lesser Black-backed Gull graellsii 2A6B adult, May 02 2014, Maasvlakte, the Netherlands. Picture: Merijn Loeve.

Lesser Black-backed Gull graellsii E040 11CY, May 30 2015, Maasvlakte, the Netherlands. Picture: Merijn Loeve.

Lesser Black-backed Gull graellsii E469 11CY, May 20 2015, Rotterdam, the Netherlands. Picture: Merijn Loeve.

LBBG 12cy AH6, May 03 2003, Voorhaven, Zeebrugge, Belgium (51.21N,03.11E). Ringed June 20 1992, now paired BWAD .

LBBG 10cy JL7, May 31 2002, Missouriweg, Maasvlakte, the Netherlands (51.59N,04.02E). Ringed June 21 1993.

LBBG 10cy LC9, May 13 2002, Dintelhaven, Maasvlakte, the Netherlands (51.59N,04.02E). Ringed June 28 1993.

LBBG 10cy LU3, May 13 2002, Hartelhaven, Maasvlakte, the Netherlands (51.59N,04.02E). Ringed June 28 1993. An example of a bird which moved to another colony (5 km's).

Lesser Black-backed Gull graellsii PJ2 15CY, 18CY, 19CY, September 2011, May 2014 & April 2015, the Netherlands. Picture: Merijn Loeve & Maarten van Kleinwee.

LBBG 6cy SE4, May 13 2002, EMO, Maasvlakte, the Netherlands (51.59N,04.02E). Ringed July 03 1997. Note the recently moulted feathers in the inner greater, inner median and central median coverts.

Lesser Black-backed Gull graellsii SY6 / NJ 17CY & 19CY, May-July 2013 and May 2015, Katwijk, the Netherlands.

Lesser Black-backed Gull graellsii TL8 8CY & 18CY, February 2006 & May 2016, Madrid, Spain & Neeltje Jans, the Netherlands.

LBBG adult TS0, May 27 2003, Dintelhaven, Maasvlakte, the Netherlands (51.59N,04.02E).

LBBG 11cy UT8, May 27 2003, Dintelhaven, Maasvlakte, the Netherlands (51.59N,04.02E). Ringed UT8 left green June 21 1993.

LBBG 9cy E129, May 27 2003, Dintelhaven, Maasvlakte, the Netherlands (51.59N,04.02E). Ringed E129 left green June 26 1995.

LBBG 9cy E835, May 27 2003, EMO - Maasvlakte, the Netherlands (51.59N,04.02E). Ringed E835 left green July 05 1995.

LBBG 10cy EE44, May 27 2003, EMO - Maasvlakte, the Netherlands (51.59N,04.02E). Ringed EE44 left green July 07 1994.

LBBG 6cy EU06, May 12 2001, Missouriweg Maasvlakte, the Netherlands. Ringed EU06 right green at Maasvlakte June 28 1996, now in it's 5th summer.

Lesser Black-backed Gull graellsii xx (formerly EX27) 19CY, May 31 2015, Maasvlakte, the Netherlands. Picture: Merijn Loeve.

LBBG 6cy EY17, May 13 2002, Dintelhaven, Maasvlakte, the Netherlands (51.59N,04.02E). Ringed June 24 1997.

LBBG 6cy EY84, May 13 2002, Dintelhaven, Maasvlakte, the Netherlands (51.59N,04.02E). Ringed June 24 1997. Probably a male. As with EY17 green, those birds return to the almost exact spot of ringing.

Lesser Black-backed Gull graellsii EAU6 17CY, May 02 2014, Maasvlakte, the Netherlands. Picture: Merijn Loeve.

Lesser Black-backed Gull graellsii X27 adult, May 02 2014, Maasvlakte-Dintelhaven, the Netherlands. Picture: Merijn Loeve.

LBBG 11cy AH1, May 12 2001 & May 23 2002, Missouriweg Maasvlakte, the Netherlands. Ringed AH1 right orange June 23 1992.

YLG (L. michahellis michahellis) 13⁺cy CU9 & adult LBBG, Missouriweg - Maasvlakte, the Netherlands, May 12 2002 (51.59N,04.02E). One of the few mixed pairs at Maasvlakte.

LBBG 'Dutch intergrade' KT1 in 10cy, May 23 2002, Maasvlakte, the Netherlands. Ringed July 07 1993.

LBBG 'Dutch intergrade' KY8 in 10cy, May 18-30 2000, Maasvlakte, the Netherlands. Born in 1991.

LBBG 'Dutch intergrade' ML2 in 10cy, May 23 2002 & May 27 2003, EMO - Maasvlakte, the Netherlands. Ringed July 08 1993.

LBBG adult SP0, May 13 2002, Hartelhaven, Maasvlakte, the Netherlands (51.59N,04.02E).

LBBG female E001 May 23 2002, Maasvlakte (EMO) the Netherlands. Ringed as adult on the nest June 1995.

LBBG & michahellis E051 May 30 2000, Maasvlakte (Naaktstrand) the Netherlands. Ringed as adult on the nest July 1995.

LBBG 8cy E052, May 12 2002, Missouriweg, Maasvlakte, the Netherlands (51.59N,04.02E). A bird ringed June 01 1995.

LBBG 8cy E053, May 12 2002, Missouriweg, Maasvlakte, the Netherlands (51.59N,04.02E). A bird ringed June 01 1995. From the same nest as E052.

LBBG 8cy E400, May 12 2002, Missouriweg, Maasvlakte, the Netherlands (51.59N,04.02E). A bird ringed on July 08 1995 near the current breeding spot.

LBBG 8cy E563, May 13 2002, Hartelhaven, Maasvlakte, the Netherlands (51.59N,04.02E). Ringed July 08 1995.

LBBG 10cy E618, May 03 2004, EMO Maasvlakte, the Netherlands (51.59N,04.02E). Ringed July 09 1995.

LBBG 9cy E835, May 27 2003, Dintelhaven, Maasvlakte, the Netherlands (51.59N,04.02E). Ringed E835 left orange at Maasvlakte July 09 1995.

LBBG 7cy E914, May 12 2001, Missouriweg Maasvlakte, the Netherlands. Ringed E914 left orange at Maasvlakte July 10 1995.

LBBG 8cy E955, May 12 2002, Missouriweg, Maasvlakte, the Netherlands (51.59N,04.02E). A bird ringed July 10 1995.

LBBG 7cy EA10, May 23 2002, EMO, Maasvlakte, the Netherlands (51.59N,04.02E). Ringed as pullus July 08 1996.

LBBG adult EC07, May 13 2002, Missouriweg, Maasvlakte, the Netherlands (51.59N,04.02E). Ring data will be added when available.

LBBG adult EC40, May 13 2002, Missouriweg, Maasvlakte, the Netherlands (51.59N,04.02E). Ring data will be added when available.

LBBG female 8cy EH79, May 12 2002, Missouriweg, Maasvlakte, the Netherlands (51.59N,04.02E). A bird ringed July 10 1995.

LBBG 7cy EJ17, May 13 2002, Hartelhaven, Maasvlakte, the Netherlands (51.59N,04.02E). Ringed at ECT, July 08 1996 near the current breeding spot.

LBBG 7cy EK85, May 12 2002, Missouriweg, Maasvlakte, the Netherlands (51.59N,04.02E). A bird ringed July 09 1996.

LBBG 9cy EK89, May 03 2004, EMO Maasvlakte, the Netherlands (51.59N 04.02E). A bird ringed July 09 1996.

LBBG 7cy EL22, May 31 2002, Missouriweg, Maasvlakte, the Netherlands (51.59N,04.02E). A bird ringed July 09 1996.

LBBG 7cy EL83, May 31 2002, Missouriweg, Maasvlakte, the Netherlands (51.59N,04.02E). A bird ringed July 09 1996.

Lesser Black-backed Gull graellsii EM41 19CY-20CY, May 23 2014 & March 30 2015, Maasvlakte, the Netherlands. Picture: Merijn Loeve.

LBBG 7cy EM86, May 12 2002, Missouriweg, Maasvlakte, the Netherlands (51.59N,04.02E). A bird ringed July 10 1996.

LBBG 7cy EN11, May 31 2002, EMO, Maasvlakte, the Netherlands (51.59N,04.02E). A bird ringed July 10 1996.

LBBG 7cy EP00, May 13 2002, Hartelhaven, Maasvlakte, the Netherlands (51.59N,04.02E). Ringed at ECT, July 13 1996 near the current breeding spot.

LBBG 7cy ET37, May 13 2002, Hartelhaven, Maasvlakte, the Netherlands (51.59N,04.02E). Ringed at ECT, July 13 1996 near the current breeding spot.

LBBG 9cy ET48, May 24 2004, Maasvlakte, the Netherlands (51.59N,04.02E). Ringed July 08 1996.

LBBG 6cy EU95, May 12 2002, Missouriweg, Maasvlakte, the Netherlands (51.59N,04.02E). A bird ringed July 02 1997.

LBBG 6cy EX13, May 23 2002, EMO, Maasvlakte, the Netherlands (51.59N,04.02E). A bird ringed July 03 1997.

LBBG 6cy EAR0, May 13 2002, Dintelhaven, Maasvlakte, the Netherlands (51.59N,04.02E). Ringed July 04 1997, on the ECT emplacement, but now breeding in the Dintelhaven colony. It's often the females which disperse over other colonies, with about 75% of the males returning to the original colony (as Herring Gull research indicated).

LBBG 7cy EAY0, female, May 12 2001, Dintelhaven Maasvlakte, the Netherlands.

LBBG 8cy ECL4, May 03 2004, EMO Maasvlakte, the Netherlands (51.59N,04.02E). A bird ringed July 03 1997.

LBBG female NT06cy, May 13 2002, Missouriweg, Maasvlakte, the Netherlands (51.59N,04.02E). Ringed July 11 1997. Note the rather parallel bill. The primary tips are relatively small, though fresh.

LBBG adult male PN5, May 13 2002, Missouriweg, Maasvlakte, the Netherlands (51.59N,04.02E). Probably ringed July 11 1997.

LBBG male 12cy R60, May 13 2002, EMO, Maasvlakte, the Netherlands (51.59N,04.02E). Ringed at the Maasvlakte as pullus, July 06 1991 near the current breeding spot.

LBBG female 12cy V90, May 12 2002, Missouriweg, Maasvlakte, the Netherlands (51.59N,04.02E). A bird ringed July 08 1991. Nest contains three eggs.

Lesser Black-backed Gull graellsii SV0 17CY, May 02-23 2014, Maasvlakte, the Netherlands. Picture: Merijn Loeve.

Lesser Black-backed Gull graellsii SX4 17CY, May 02-23 2014, Maasvlakte, the Netherlands. Picture: Merijn Loeve.

Lesser Black-backed Gull graellsii N09V adult, May 02 2014, Maasvlakte, the Netherlands. Picture: Merijn Loeve.

Lesser Black-backed Gull graellsii N0LH adult, May 23 2014, Maasvlakte, the Netherlands. Picture: Merijn Loeve.

Lesser Black-backed Gull graellsii N0LL adult, May 01 2014, Maasvlakte, the Netherlands. Picture: Merijn Loeve.

LBBG adult J7, May 12 2002, Missouriweg, Maasvlakte, the Netherlands (51.59N,04.02E).

LBBG adult 1 7, May 12 2002, Missouriweg, Maasvlakte, the Netherlands (51.59N,04.02E).

Lesser Black-backed Gull graellsii E019 6CY & 11CY, May 2004 & Augsut 2009, Maasvlakte & Westkapelle, the Netherlands.

LBBG 6cy E022 May 24 2004, Missouriweg Maasvlakte, the Netherlands (51.59N 04.02E).

LBBG 6cy E136 May 03 2004, EMO Maasvlakte, the Netherlands (51.59N 04.02E).

Lesser Black-backed Gull graellsii EE328 15CY, May 13 2014, Sassenplaat, the Netherlands. Picture: Merijn Loeve.

LBBG 6cy E800 May 2009, Moerdijk, the Netherlands.

LBBG adult NLA 5.285.764, May 12 2002, Missouriweg, Maasvlakte, the Netherlands (51.59N,04.02E). An old Dutch aluminum ring, probably ringed 1992.

LBBG adult (15cy) male NLA 5.248.912, May 12 2002, Missouriweg, Maasvlakte, the Netherlands (51.59N,04.02E). An old Dutch aluminum ring, ringed 1988.

LBBG adult (14cy) female NLA 5.257.580, May 12 2002, Missouriweg, Maasvlakte, the Netherlands (51.59N,04.02E). An old Dutch aluminum ring, hardly readable. Ringed July 09 1989, ECT-Maasvlakte as pullus.

LBBG adult (14cy) female NLA 5.257.218, May 12 2002, Missouriweg, Maasvlakte, the Netherlands (51.59N,04.02E). An old Dutch aluminum ring, hardly readable. Again ringed July 09 1989, ECT-Maasvlakte as pullus.

LBBG adult female NLA 5.181.236, May 12 2002, Missouriweg, Maasvlakte, the Netherlands (51.59N,04.02E). An old Dutch aluminum ring: Ringstation Arnhem. Ringed June 27 1984, B.P. terminals, Rozenburg as pullus, a distance of 5 km from the current location.

LBBG adult (13cy) male NLA 5.222.908, May 13 2002, Missouriweg, Maasvlakte, the Netherlands (51.59N,04.02E). An old Dutch aluminum ring: Ringstation Arnhem. Ringed July 19 1990, ECT-Maasvlakte as pullus.

LBBG adult NLA 5.321.306, May 27 2003, Dintelhaven, Maasvlakte, the Netherlands (51.59N,04.02E).

LBBG female 6cy NLA 5.330.587, May 13 2002, Missouriweg, Maasvlakte, the Netherlands (51.59N,04.02E). An new Dutch aluminum ring: Ringstation Arnhem. Ringed June 24 1997, IJmuiden as pullus.

LBBG female adult NLA 5.332.974, May 03 2004, EMO Maasvlakte, the Netherlands (51.59N 04.02E).

LBBG 5cy NLA 5.404.820 May 05 2011, IJmuiden, the Netherlands.

LBBG 5cy NLA 5.416.820 May 05 2011, IJmuiden, the Netherlands.

Lesser Black-backed Gull graellsiiNLA 5.417.298 adult, May & June 2015 & March 2016, Boulogne-sur-Mer, NW France. Picture: Jean-Michel Sauvage.

Lesser Black-backed Gull graellsiiNLA 5.464.846 6CY, May 11 2016, Europoort (Dintelhaven), the Netherlands (51.57.00 N 04.06.00 E).

Lesser Black-backed Gull graellsii NLA 5.467.787 7CY, May 10 2017, Katwijk, the Netherlands.

Lesser Black-backed Gull graellsiiNLA 5.472.386 5CY, May 11 2016, Maasvlakte (Amazonehaven), the Netherlands (51.56 N 04.03 E).

Lesser Black-backed Gull graellsiiNLA 5.504.144 adult, May 02 2017, Texel, the Netherlands.

LBBG adult Madrid 6003175, May 13 2002, Missouriweg, Maasvlakte, the Netherlands (51.59N 04.02E). An new Spanish aluminum ring: Minist. Agricultura Icona Madrid.