Lesser Black-backed Gull (graellsii & intermedius)
(last update:
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lbbg sub-ad Sept
lbbg sub-ad Oct
lbbg sub-ad Nov
lbbg sub-ad Dec
lbbg adult January
lbbg adult February
lbbg adult March
lbbg adult April
lbbg adult May
lbbg adult June
lbbg adult July
lbbg adult August
lbbg adult September
lbbg adult October
lbbg adult November
lbbg adult December
adult: September
By September, the large majority of adult LBBG have left the Netherlands and must have move south towards Portugal. Many of the Dutch adults, which were seen feeding youngs and those suspending primary moult start migrating and must have joint these migrating groups. Nevertheless, many adults can still be found in the Netherlands, but as September progresses, more adults from Scandinavian intermedius colonies move in. This may be a reason for the "observed mere stand-still in primary moult progress" in adults: less advanced individuals from Scandinavia congregate with local Dutch intergrades.
In this September Section we present primary moult score surveys 2001 & 2002 from the Netherlands (Maasvlakte) and NW France (Boulogne-sur-Mer). No definite conclusions on geographical variations can be drawn from these data. Therefore we started to focus on ringed adults only from year 2003 onwards; metal ringed and Darvic ringed birds of known origin.
Anyone checking local Lesser Black-backed Gulls in September will have noticed the large individual variation in primary moult scores. The commencement and pace of primary moult is an individual "choice", influenced by other prime goals like feeding pulli and migration. The birds observed in NW Europe apparently "chose" to stay and their September primary moult scores are not necessarily representative for "average NW European LBBG", as we simply do not know the primary moult strategy of early migrating adults.
So two question can be raised: how to exclude influences from northern populations and what PMS can be expected in early migrating birds?
Best option to reduce the second problem culd be found in simultaneous counts along the entire West European coastline, or counts which only involve ringed individuals (thus from certain origin) at stop-overs and winter quarters. Particularly those adults which migrate south as soon and as quick as possible, may be found with low PMS or suspended moult.
In the Netherlands we concentrate on ringed individuals to eliminate the first problem (intermedius joining local Dutch intergrades), but we still have insufficient ring observations to make reliable analyses possible.
The problem of (presumed) later moulting intermedius, moving into early moulting graellsii groups is not a problem restricted to adults, but applies to other age-classes as well.
Although the input of later moulting intermedius may be expected, the average primary moult score is hardly influenced as it seems. From the table below, the average "remaining old primary score" falls by almost two primaries over a period of 4 weeks. This matches nicely with the August estimates.
| remaining old primaries in adult LBBG's, Maasvlakte, September 2001. | ||||||||||||||||
| 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | n: | m: | V: | SD: | SE: | |
| 01/09 | 3 | 3 | 6 | 5 | 15 | 47 | 38 | 19 | 1 | - | - | 137 | 4,9 | 2,46 | 1,57 | 0,13 |
| 11/09 | 2 | 2 | 5 | 9 | 7 | 16 | 53 | 81 | 31 | 9 | - | 215 | 3,7 | 2,75 | 1,66 | 0,11 |
| 17/09 | - | - | 1 | 2 | 6 | 11 | 24 | 39 | 11 | 4 | - | 98 | 3,6 | 1,77 | 1,33 | 0,13 |
| 28/09 | - | - | - | 2 | 5 | 14 | 23 | 62 | 40 | 10 | - | 156 | 3,1 | 1,51 | 1,23 | 0,10 |
| First cell (10, 01/09 = 3) should be read: on September first, 3 adults had all 10 primaries old, hence showed no primary moult yet (this is about 2% on 137 observed adults that day). n: observations, m: average, V: variance (s2), SD: standard deviation (s), SE: standard error (s· n½). |
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| Old and new primaries in adult LBBG's, Dannes(NW France), Sept 21-22 2002. | |||||||
| old prims | p6 old | p7 old | p8 old | p9 old | p10 old | no old | n old: |
| p7 new | - | - | - | - | 6 | 5 | 11 |
| p6 new | - | - | 4 | 45 | 18 | 1 | 68 |
| p5 new | - | - | 39 | 18 | 2 | - | 59 |
| p4 new | - | 7 | 1 | - | - | - | 8 |
| p3 new | 4 | - | - | - | - | - | 4 |
| ? new | 1 | 10 | 2 | - | - | - | 13 |
| n new: | 5 | 17 | 46 | 63 | 26 | 6 | 163 |
As can be seen in the table, the average LBBG has a three primaries moult gap. |
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Subspecific PMS: graellsii
In the Netherlands, the nominate type graellsii can be found in low numbers in September. Normally, they can be recognized by their slightly paler grey upper-parts, fiercer facial expression, stockier jizz and more advanced PMS. By September, adult graellsii may arrive from Britain, but the nominate form also can be found breeding in Belgian and Dutch colonies.
We do not collect sufficient field data on ringed graellsii in the Netherlands to draw any conclusions; notwithstanding the fact that September adults disperse throughout the entire southern part of the North Sea, following vessels on rich fishing grounds and taking rest at the closest beaches, either in Britain, Belgium or the Netherlands.
There are hardly articles or papers dealing with September adult LBBG. By far the most extensive surveys were done by the Severn Estuary Gull Group in Gloucestershire, with LBBG-expert Peter Stewart. He wrote two papers on PMS of British graellsii, one still in preparation.
During the period February 1986 to October 2001 no less than 12,842 LBBG were caught using cannon-nets, and from this total 6,539 PMS were recorded. For the month September, 407 adults have been recorded. The number of old primaries present in adults are presented in the table below. Peter uses half monthly intervals.
Extracted from: Table 3. The number of old primaries present during the moulting season. |
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| time interval | mean (m) | range | sample size (n) |
| Sept 01-15 | 3.3 | 0-7 | 234 |
| Sept 16-30 | 2.1 | 0-7 | 173 |
Table 3 from "The primary moult of the Lesser Black-backed Gull" by Peter Stewart (in prep, 2002). Special Publication No 1 by The Severn Estuary Gull Group. |
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Peter also recorded the PMS of adult birds, using the method described by Ginn & Melville (1983). Each primary receives a score: score 0 (old feathers), score 1 (old feather missing, new feather completely in pin), score 2 (new feather visible up to 1/3), score 3 (growing feather 1/3 to 2/3), score 4 (growing feather more than 2/3, still with basal waxy sheath), score 5 (new feather fully grown). The total PMS for all 10 primaries varies from 0 to 50 for any single wing.
Extracted from: Table 9. The PMS at half-monthly intervals in adults (aggregated n: 4472). |
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| time interval | mean (m) | range | sample (n) | moulting n | moulting % |
| Sept 01-15 | 26.8 | 6-44 | 239 | 239 | 100 |
| Sept 16-30 | 32.1 | 11-47 | 107 | 107 | 100 |
Table 9 from "The primary moult of the Lesser Black-backed Gull" by Peter Stewart (in prep, 2002). Special Publication No 1 by The Severn Estuary Gull Group. |
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Subspecific PMS: Dutch intergrade
The form "Dutch intergrade" refers to the LBBG populations in Belgium and the Netherlands. These colonies are situated between graellsii (British Isles) and intermedius (Norway, Sweden, Demark) and breeding birds in the Netherlands and Belgium show characters of both taxa. We have extensive field surveys of primary moult scores for adult LBBG from the large colony at Maasvlakte (near Rotterdam) but the September scores may be effected by migrating intermedius, which are abundant, especially in the second half of the month. From 2003 onwards, we focus on ringed birds only, making sure birds originate from the Netherlands or Belgium. Although the figures in the table give some indication for the average PMS of Dutch LBBG, a few comments must be made:
1. The PMS recorded here refer to LBBG which are still in the Netherlands. We don't have sufficient data to draw conclusions on the complete Dutch population.
2. Different colonies are involved, with birds from Maasvlakte, IJmuiden and Moerdijk (inland location).
3. Although it seems easy to construct a PMS progression line, this is not wise. Especially the counts for September involve many different birds, only seen on one or a few occasions. Individual birds follow different moult strategies, and this may vary between Dutch colonies.
The number of old primaries present during the moulting season in ringed adult LBBG from Belgium & the Netherlands 2003. |
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| time interval | mean (m) | range | sample size (n) |
| Sept 01-15 | 3.2 | 2-5 | 26 |
| Sept 16-30 | 2.4 | 0-4 | 32 |
Notes: |
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Subspecific PMS: intermedius
The form intermedius breeds in Norway, Sweden and Demark. Compared to either graellsii or Dutch intergrades, intermedius is on average a late moulting bird. Most birds are a shade of grey darker than Dutch intergrades, but some intermedius appear just as grey and robust as the average local Dutch intergrade. However, strong western September winds may bring the typical small intermedius to Dutch shores, very dark grey (almost blackish) with typical jizz: short necked, short legged, attenuated rear end and dove-like appearance. And often a remarkable low PMS. The few comments made under the Dutch intergrade caption apply to intermedius as well.
The number of old primaries present during the moulting season in ringed adult LBBG from Norway, Sweden & Denmark 2003. |
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| time interval | mean (m) | range | sample size (n) |
| Sept 01-15 | 4.5 | 2-7 | 24 |
| Sept 16-30 | 3.8 | 2-5 | 9 |
Notes: |
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Peter Stewart has caught intermedius in Britain. He only recorded 10 birds for September on a total of 68 birds. The average PMS for intermedius "falls mainly between the mean and lowest moult scores obtained for adult graellsii", according to Peter. However, intermedius may show a very advanced PMS as well, already by mid-August.
Extracted from: Table 18. Summary of PMS for 68 L.f. intermedius at half-monthly intervals in adults. |
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| time interval | mean (m) | range | sample (n) | moulting n | moulting % |
| Sept 01-15 | 20.1 | 12-28 | 9 | 9 | 100 |
| Sept 16-30 | 27.0 | 27 | 1 | 1 | 100 |
Table 18 from "The primary moult of the Lesser Black-backed Gull" by Peter Stewart (in prep, 2002). Special Publication No 1 by The Severn Estuary Gull Group. |
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conclusions
As could be expected, LBBG which spend the month of September along the Dutch coast may origin from many different colonies. The PMS of either graellsii, Dutch intergrades or intermedius do not necessarily reflect the average of a complete LBBG population, as many birds quickly migrate south, early in the season. Particularly these birds may follow a different (delayed) moult strategy.
Tables & Graph
| starting date:
|
|
|
|
|
|
|
| week no:
|
35
|
36
|
37
|
38
|
39
|
40
|
| REM 0
|
0
|
0
|
0
|
6
|
0
|
2
|
| REM 1
|
0
|
0
|
9
|
38
|
19
|
1
|
| REM 2
|
3
|
4
|
33
|
95
|
85
|
2
|
| REM 3
|
66
|
25
|
100
|
111
|
123
|
2
|
| REM 4
|
187
|
24
|
57
|
51
|
44
|
0
|
| REM 5
|
182
|
4
|
17
|
17
|
24
|
0
|
| REM 6
|
105
|
0
|
7
|
6
|
9
|
0
|
| REM 7
|
33
|
0
|
9
|
2
|
5
|
0
|
| REM 8
|
25
|
0
|
5
|
1
|
1
|
0
|
| REM 9
|
15
|
0
|
2
|
0
|
0
|
0
|
| REM 10
|
14
|
0
|
2
|
0
|
0
|
0
|
|
|
0
|
0
|
0
|
0
|
0
|
0
|
| n =
|
630
|
57
|
241
|
327
|
310
|
7
|
| average P =
|
5.1
|
3.5
|
3.6
|
2.8
|
3.1
|
1.6
|
| 95% CID =
|
0.12
|
0.19
|
0.20
|
0.14
|
0.14
|
1.18
|
| inverse =
|
1.96
|
2.00
|
1.97
|
1.97
|
1.97
|
2.45
|
| Variantie (s2) =
|
2.43
|
0.54
|
2.52
|
1.58
|
1.57
|
1.62
|
| SD (s) =
|
1.56
|
0.73
|
1.59
|
1.26
|
1.25
|
1.27
|
| SE (sx) =
|
0.06
|
0.10
|
0.10
|
0.07
|
0.07
|
0.48
|
|
|
|
|
|
|
|
|
| % class:
|
|
|
|
|
|
|
| 0
|
0
|
0
|
0
|
2
|
0
|
29
|
| 1
|
0
|
0
|
4
|
12
|
6
|
14
|
| 2
|
0
|
7
|
14
|
29
|
27
|
29
|
| 3
|
10
|
44
|
41
|
34
|
40
|
29
|
| 4
|
30
|
42
|
24
|
16
|
14
|
0
|
| 5
|
29
|
7
|
7
|
5
|
8
|
0
|
| 6
|
17
|
0
|
3
|
2
|
3
|
0
|
| 7
|
5
|
0
|
4
|
1
|
2
|
0
|
| 8
|
4
|
0
|
2
|
0
|
0
|
0
|
| 9
|
2
|
0
|
1
|
0
|
0
|
0
|
| 10
|
2
|
0
|
1
|
0
|
0
|
0
|
|
|
|
|
|
|
|
|
|
|
100
|
100
|
100
|
100
|
100
|
100
|
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 September (arrested moult excluded). Sample size for this graph is 278 ringed birds + 1294 unringed birds.
starting date:
|
27-Aug
|
10 Sep
|
17 Sep
|
24 Sep
|
08 Oct
|
week no:
|
35
|
37
|
38
|
39
|
41
|
NEW 0
|
1
|
0
|
0
|
0
|
0
|
NEW P1
|
0
|
0
|
0
|
0
|
0
|
NEW P2
|
2
|
0
|
0
|
0
|
0
|
NEW P3
|
12
|
0
|
4
|
0
|
0
|
NEW P4
|
25
|
6
|
11
|
4
|
0
|
NEW P5
|
5
|
13
|
65
|
10
|
1
|
NEW P6
|
0
|
11
|
73
|
4
|
12
|
NEW P7
|
0
|
3
|
15
|
0
|
5
|
NEW P8
|
0
|
0
|
0
|
0
|
0
|
NEW P9
|
0
|
0
|
0
|
0
|
0
|
NEW P10
|
|
|
|
|
|
|
|
|
|
|
|
n =
|
45
|
33
|
168
|
18
|
18
|
average NEW P =
|
3.7
|
5.3
|
5.5
|
5.0
|
6.2
|
95% CID =
|
0.27
|
0.32
|
0.13
|
0.34
|
0.27
|
inverse =
|
2.02
|
2.04
|
1.97
|
2.11
|
2.11
|
Variantie (s2) =
|
0.82
|
0.79
|
0.71
|
0.47
|
0.30
|
SD (s) =
|
0.90
|
0.89
|
0.84
|
0.69
|
0.55
|
SE (sx) =
|
0.13
|
0.15
|
0.06
|
0.16
|
0.13
|
|
|
|
|
|
|
% class
|
|
|
|
|
|
0
|
2
|
0
|
0
|
0
|
0
|
1
|
0
|
0
|
0
|
0
|
0
|
2
|
4
|
0
|
0
|
0
|
0
|
3
|
27
|
0
|
2
|
0
|
0
|
4
|
56
|
18
|
7
|
22
|
0
|
5
|
11
|
39
|
39
|
56
|
6
|
6
|
0
|
33
|
43
|
22
|
67
|
7
|
0
|
9
|
9
|
0
|
28
|
8
|
0
|
0
|
0
|
0
|
0
|
9
|
0
|
0
|
0
|
0
|
0
|
10
|
0
|
0
|
0
|
0
|
0
|
|
|
|
|
|
|
% control:
|
100
|
100
|
100
|
100
|
100
|
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 September (arrested moult excluded). Sample size for this graph is 112 ringed birds + 152 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).
|
Netherlands
|
|
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|
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.
.
Lesser Black-backed Gull graellsii Y250 adult, September - December 2016, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii YE05 8CY, September 08 2015, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii ISR 351412 adult, September 06 2017, Leixões Harbour, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii ISR 352013 adult, September 01 2017, Leixões Harbour, Matosinhos, Portugal. Picture: José Marques..
Lesser Black-backed Gull graellsii T:87J adult, September - December 2015 - March 2016 & October 2016 - March 2017, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 18S:C adult, September 06 2017, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 3Z3:C adult, September 06 2017, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 0.V7 7CY-9CY, September 2015 - September 2017, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 1.X1 adult, September 01 2015, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 5.C3 7CY-8CY, September 2016 & 2017, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 5.T9 8CY, August - September 2017, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 6.C7 7CY-8CY, February & October 2016, September 2017, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 0AT7 adult, September - October 2016, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 0AV3 adult, September 16 2016, Matosinhos Beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 0AW4 adult, September 16 2016, Matosinhos Beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 0CT1 adult, September 25 2017, Leça beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 0FA1 adult, September - October 2016, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 1AH4 adult, October 2016 & September 2017, Espinho & Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 1AT0 adult, September 2015 & November 2016, Matosinhos Beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 1AV8 5CY, September 29 2017, Leixões harbour, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 1CJ1 adult, September 15 2017, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 1FA1 adult, September - November 2016, Matosinhos Beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 2AK8 adult, September - October 2015, Matosinhos Beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 2CT2 adult, September 22 2016, Leça Beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 3AJ4 adult, September 15 2017, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 3AL2 adult, September - October 2015, September 2016 - January 2017, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 3AU9 adult, August - October 2015, 2016 & 2017, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 3AX9 adult, October - November 2016 & September 2017, Espinho Beach, Espinho, Aveiro, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 3CT2 adult, September 2016 & 2017, Matosinhos Beach, Matosinhos, Portugal. Picture: José Marques. 
Lesser Black-backed Gull graellsii 3CF0 adult, September 01 2015, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 4AF8 adult, September - October 2016, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 4AH8 11CY, September 21 2017, Mira beach, Coimbra, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 4AM6 7CY & 9CY, September 2015 & August 2017, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 4AX5 adult, March - December 2015, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 4AZ1 adult, September 16 2016, Matosinhos Beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 5AV1 adult, September 01 2015, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 5CC4 adult, September -October 2015, Matosinhos Beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 5CH2 adult, September 01 2016, Matosinhos, Portugal. Picture: José Marques. 
Lesser Black-backed Gull graellsii 5CJ1 5CY-6CY, February 2016 & August - September 2017, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 5CT1 adult, September - October 2016, Matosinhos Beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 5FA2 3CY-5CY, August-September 2015 & September 2016 - March 2017, September 2017, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 6AK9 adult, September 08 2015, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 6AM4 adult, September 01 2015, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 6AN1 4CY-6CY, March 2015 - September 2017, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 6AX6 adult, September 06 2017, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 6CF6 adult, October 2015 - September 2017, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 6CH4 adult, September - October 2016, Matosinhos Beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 6CH8 adult, September 01 2017, Leixões harbour, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 6CL1 adult, September 16 2016, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques. 
Lesser Black-backed Gull graellsii 7AX0 adult, December 2015, November 2016 & August-September 2017, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 7CL6 adult, September 04-05 2015, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 7FA7 adult, September 01 2015, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 8AC0 adult, October 2015 - September 2017, Matosinhos Beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 8AH9 adult, September 21 2017, Mira beach, Coimbra, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 8AJ1 adult, November - December 2015 & September 2017, Matosinhos Beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 8AK3 adult, October 2015 - September 2017, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 8AL5 adult, September 26 2017, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 8AM2 adult, October 2015 & September 2017, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 8AV7 adult, September 16 2016, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques. 
Lesser Black-backed Gull graellsii 8CA3 adult, September 02 2016, Leixões harbour, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 8CL3 adult, September 2016 & January 2017, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 8CL6 adult, September - October 2015 & August 2017, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 8CS1 adult, September - November 2016, Leixões harbour, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 8CS7 adult, September 01 2015, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 9AH6 adult, September - December 2016, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 9AM0 adult, September 26 2017, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 9AT6 adult, September - October 2016, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 9AT9 adult, September 01 2015, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 9CF6 adult, September - October 2016, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 9CJ0 adult, September 2016 & 2017, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques. 
Lesser Black-backed Gull graellsii 3.U0 adult, August - September 2017, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 4.Z3 9CY, September - November 2016, Torreira beach, Beira Litoral, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 1KH adult, September 21 2008, Madrid, Spain. Photo by Delfín González.
Lesser Black-backed Gull graellsii 6SF 5CY & 7CY, March & October 2015, February & September 2017, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii F:Z 11CY, September - November 2015, Matosinhos Beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii B:V 14CY-15CY, September 2015 & October 2016, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii F:C 14CY, September 29 2015, Leixões harbour, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii G:J 14CY, September 21 2017, Mira beach, Coimbra, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii R:M 14CY, September 15 2017, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 2VH adult, September 29 2015, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 5JG adult, September - October 2015, Matosinhos Beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 5LF adult, September 26 2017, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 7X:W adult, September 01 2015, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 9H:W adult, September - October 2015, Matosinhos Beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii CST adult, September 29 2015, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii DZH 10CY, September 21 2017, Mira beach, Coimbra, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii GBT GN 62664 adult, September 04 2010, Leiden, the Netherlands.
Lesser Black-backed Gull graellsiiBTO GK 38437 26CY-30CY, 2008-2011, Boulogne sur mer, NW France. Picture: Jean-Michel Sauvage.
Lesser Black-backed Gull graellsiiGBT GG 63019 15CY, September 02 2003, Westkapelle, the Netherlands.
Lesser Black-backed Gull graellsiiGBT GG 44337 19+CY, September 02 2003, Westkapelle, the Netherlands..
Lesser Black-backed Gull graellsii 4F-3002 adult, September - November 2016, Matosinhos Beach, Matosinhos, Portugal. Picture: José Marques..
Lesser Black-backed Gull graellsii 188K 10CY, September - October 2016, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii R:C6V adult, September - October 2016 & September 2017, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii R:E1J adult, September - October 2016, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii R:K0T adult, September 01 2016, Matosinhos Beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii R:K8S adult, September 26 2017, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii R:K9E adult, October 2015 & September 2017, Matosinhos Beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii R:R9T adult, September 06-12 2017, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii R:S3S 5CY, September 21 2017, Mira beach, Coimbra, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii FRP DB100210 10CY-11CY, November 2016 & September 2017, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques..
Lesser Black-backed Gull graellsiiBLB L-87152 5CY, September 02 2003, Westkapelle, the Netherlands. 5cy, ringed in 1999.
Lesser Black-backed Gull graellsii BLB L-900115 7CY, September 03 2010, Boulogne sur mer, NW France. Picture: Jean-Michel Sauvage.
Lesser Black-backed Gull graellsii BLB L-902350 adult, September 14 2015, Boulogne-sur-Mer, NW France. Picture: Jean-Michel Sauvage.
Lesser Black-backed Gull graellsii BLB L-913074 adult, September 08 2016, Boulogne-sur-Mer, France. Picture Jean-Michel Sauvage.
Lesser Black-backed Gull graellsii BLB L-91728x adult, September 30 2016, Westkapelle, the Netherlands. 
Lesser Black-backed Gull graellsii A.L0H adult, September - October 2016, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii BVAM 7+CY, September 02 2003, Westkapelle, the Netherlands.
Lesser Black-backed Gull graellsii DKAN 15CY & 17CY, October 2009 & September 2011, Westkapelle, the Netherlands.
Lesser Black-backed Gull graellsii HD.AB 8CY, September 08 2015, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii LT.AD 7CY, September 05 2015, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii N.GAN 11CY, September 13 2016, Leixões Harbour, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii U.AAP adult, September 01 2016, Matosinhos Beach, Matosinhos, Portugal. Picture: José Marques. .
Lesser Black-backed Gull graellsii NLA 5.292.328 8CY, September 12 2015, Utrecht, the Netherlands.
Lesser Black-backed Gull graellsii NLA 5.326.111 adiult, September 02 2003, Westkapelle, the Netherlands.
Lesser Black-backed Gull graellsii NLA 5.330.599 19CY, September 03 2015, IJmuiden, the Netherlands.
Lesser Black-backed Gull graellsiiNLA 5.330.969 14CY-15CY, September 2010 & August 2011, Boulogne sur mer, NW France. Picture: Jean-Michel Sauvage.
Lesser Black-backed Gull graellsii NLA 5.461.4x6 adult, September 04 2015, Utrecht, the Netherlands.
Lesser Black-backed Gull graellsii C||3 adult, September 01 2016, Matosinhos Beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii DK 10CY, September 16 2016, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques. 
Lesser Black-backed Gull graellsii XJ 8CY, September 19 2013, Katwijk, the Netherlands.
Lesser Black-backed Gull graellsii 08 7CY, September 22 2016, Leça Beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 8+ (was PR4) 20cy, September 01 2016, Matosinhos Beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii CY 7CY & 9CY, July 2014 & September - November 2016, NW France & Portugal. Picture: Jean-Michel Sauvage & José Marques.
Lesser Black-backed Gull graellsii C+ adult, September 15 2015, Den Haag, the Netherlands. Picture: Merijn Loeve.
Lesser Black-backed Gull graellsii L6 7CY, September 01 2015, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii TN 15CY, September 13 2013, Boulogne-sur-Mer, NW France. Picture: Jean-Michel Sauvage.
Lesser Black-backed Gull graellsii E.M 7CY, September 01 2015, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii AX adult, September 15 2010, Westkapelle, the Netherlands.
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 graellsii 1.N 6CY, September 26 2016, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii D7 adult, August - September 2010, Boulogne sur mer, NW France. Picture: Jean-Michel Sauvage.
Lesser Black-backed Gull graellsii PC adult, September 23 2010, Westkapelle, the Netherlands.
Lesser Black-backed Gull graellsii 45 adult, September 16 2016, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques. 
Lesser Black-backed Gull graellsii 6K adult, September 2015 & December 2016, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii 8M adult, September 01 2016, Matosinhos Beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii RF adult, September 26 2016, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii VS adult, September 06 2013, Comenar Viejo, Madrid, Spain (40°15'41"N 003°38'00"W). Picture: Delfín Gonzalez.
Lesser Black-backed Gull graellsii BF adult, September 16 2016, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques. 
Lesser Black-backed Gull graellsii CS adult, September 16 2016, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques. 
Lesser Black-backed Gull graellsii CX adult, September 08 2015, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques. 
Lesser Black-backed Gull graellsii D7 adult, September 29 2015, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii GX adult, October - November 2016 & September 2017, Matosinhos Beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii T2 adult, May 2005, May 2006, November 2015 - September 2017, the Netherlands & Portugal. Picture: Mars Muusse & José Marques.
Lesser Black-backed Gull graellsii K.YAY 7CY-9CY, September 2015, October 2016 & February 2017, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii M.AAV adult, September 08 2008, Madrid, Spain. Photo by Delfín González.
Lesser Black-backed Gull graellsii Y.ABY adult, September 01 2011, IJmuiden, the Netherlands.
Lesser Black-backed Gull graellsii Y.AHJ adult, 2009-2011, France & the Netherlands. Pictures: Ruud Altenburg & Jean-Michel Sauvage.
Lesser Black-backed Gull graellsii Y.AKU adult, September 2010 & September 2016, IJmuiden, the Netherlands.
Lesser Black-backed Gull graellsii Y.AKZ adult, 2010-2011, IJmuiden-Westkapelle, the Netherlands.
Lesser Black-backed Gull graellsii Y.ARV 7CY, September 07 2016, IJmuiden, the Netherlands.
Lesser Black-backed Gull graellsii Y.AZP 3CY & 6CY, June 2013 & September 2016, the Netherlands & Portugal. Picture: Mars Muusse & José Marques.
Lesser Black-backed Gull graellsii Y.BAC adult, September - October 2016 & September 2017, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii Y.BBB adult, September 07 2016, IJmuiden, the Netherlands.
Lesser Black-backed Gull graellsii Y.BJC adult, September 14 2015, Boulogne-sur-Mer, NW France. Picture: Jean-Michel Sauvage.
Lesser Black-backed Gull graellsii Y.BUP adult, September 11 2015, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques. 
Lesser Black-backed Gull graellsii Y.CHW adult, September 15 2017, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii P84 14CY, September 27 2004, Westkapelle, the Netherlands. Ringed as pullus in 1991.
Lesser Black-backed Gull graellsii JP0 18CY, September 23 2010, Westkapelle, the Netherlands.
Lesser Black-backed Gull graellsii EJ83 15CY, August-September 2010, Boulogne sur mer, NW France. Picture: Jean-Michel Sauvage.
Lesser Black-backed Gull graellsii ES29 8CY, September 02 2003, Westkapelle, the Netherlands.
Lesser Black-backed Gull graellsii EX68 12CY, September 02 2008, Boulogne sur mer, NW France. Picture: Jean-Michel Sauvage.
Lesser Black-backed Gull graellsii E703 9CY, September 02 2003, Westkapelle, the Netherlands.
Lesser Black-backed Gull graellsii EAH9 6CY, 8CY, 10CY, September 23 2006, Madrid, Spain. Photo by Delfín González. 
Lesser Black-backed Gull graellsii EP94 9CY, September 30 2004, Westkapelle, the Netherlands. Picture Pim Wolf.
Lesser Black-backed Gull graellsii PJ2 15CY, 18CY, 19CY, September 2011, May 2014 & April 2015, the Netherlands. Picture: Merijn Loeve & Maarten van Kleinwee.
Lesser Black-backed Gull graellsii RS7 15CY, September 01 2011, IJmuiden, the Netherlands.
Lesser Black-backed Gull graellsii X11 adult, September 01 2011, IJmuiden, the Netherlands.
Lesser Black-backed Gull graellsii E494 adult, September 20 2003, IJmuiden, the Netherlands.
Lesser Black-backed Gull graellsii E699 11CY-12CY, September 09 2011 & August 20 2012, Katwijk, the Netherlands.
Lesser Black-backed Gull graellsii E225 adult, September 01 2010, Westkapelle, the Netherlands.
Lesser Black-backed Gull graellsii N527 adult, September 02 2010, Heemskerk, the Netherlands. Ringed in Spain in winter.
Lesser Black-backed Gull graellsii NLA 5.472.267 5CY, September 09 2016, Utrecht, the Netherlands..
Lesser Black-backed Gull graellsii H.010 4CY, September 01 2010, Westkapelle, the Netherlands.
Lesser Black-backed Gull graellsii H.501 3CY-5CY, September - October 2010, Leiden, the Netherlands..
Lesser Black-backed Gull intermedius VC5M adult, September 23 2010, Westkapelle, the Netherlands.
Lesser Black-backed Gull intermedius VL9M 1CY & 5CY, September 2011 & 2015, Westkapelle & IJmuiden, the Netherlands. Picture: Maarten van Kleinwee & Mars Muusse.
Lesser Black-backed Gull intermedius DKC 421170x adult, September 24 2009, Westkapelle, the Netherlands. .
Lesser Black-backed Gull intermedius J29E 16CY, September 24 2009, Westkapelle, the Netherlands.
Lesser Black-backed Gull intermedius J3RY 8CY, September 19 2017, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull intermedius J4LU 25CY, September 05 2015, Matosinhos Beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull intermedius J5LE 17CY, September 08 2015, Matosinhos Beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull intermedius JAE2 adult, September 06 2013, Comenar Viejo, Madrid, Spain. Picture: Delfín Gonzalez. 
Lesser Black-backed Gull intermedius JCJ8 9CY, September 30 2016, Westkapelle, the Netherlands.
Lesser Black-backed Gull intermedius JET1 10CY, September 08 2017, Boulogne-sur-Mer, France. Picture: Jean-Michel Sauvage.
Lesser Black-backed Gull intermedius JH77 5CY, September 23 2010, Westkapelle, the Netherlands.
Lesser Black-backed Gull intermedius JR1V 6CY, September 21 2017, Mira beach, Coimbra, Portugal. Picture: José Marques.
Lesser Black-backed Gull intermedius J192A adult, September 30 2016, Westkapelle, the Netherlands.
Lesser Black-backed Gull intermedius J330V adult, September 26 2017, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull intermedius J446N adult, September 19 2017, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull intermedius J493H adult, September 26 2017, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull intermedius J537E 5CY, September 22 2017, Leixões harbour, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull intermedius J949V adult, September 08 2017, Boulogne-sur-Mer, France. Picture: Jean-Michel Sauvage.
Lesser Black-backed Gull intermedius JCA0 6CY, September 20 2003, IJmuiden, the Netherlands.
Lesser Black-backed Gull intermedius JMP8 7CY, September 27 2007, Westkapelle, the Netherlands. Picture Pim Wolf.
Lesser Black-backed Gull intermedius JP0P 6CY, September 24 2009, Westkapelle, the Netherlands.
Lesser Black-backed Gull intermedius JPP1 19CY, September 26 2017, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull intermedius JU28 4CY, September 28 2004, Westkapelle, the Netherlands. Picture Pim Wolf.
Lesser Black-backed Gull intermedius NOS 4100410 19cy, September 27 2004, Westkapelle, the Netherlands. Picture Pim Wolf. Returning adult.
Lesser Black-backed Gull intermedius NOS 4107441 18cy, September 02 2003, Westkapelle, the Netherlands.
Lesser Black-backed Gull intermedius NOS 4147932 15CY, September 07 2004, Westkapelle, the Netherlands. Picture Pim Wolf.
Lesser Black-backed Gull intermedius NOS 4153395 14cy, September 02 2003, Westkapelle, the Netherlands.
Lesser Black-backed Gull intermedius NOS 4164893 14cy, September 02 2003, Westkapelle, the Netherlands.
Lesser Black-backed Gull intermedius NOS 416x044 adult, September 02 2003, Westkapelle, the Netherlands.
Lesser Black-backed Gull intermedius NOS 416x366 adult, September 22 2003, IJmuiden, the Netherlands.
Lesser Black-backed Gull intermedius NOS 4178117 13cy, September 26 2003, IJmuiden, the Netherlands.
Lesser Black-backed Gull intermedius NOS 4178334 13cy, September 20 2003, IJmuiden, the Netherlands.
Lesser Black-backed Gull intermedius NOS 4194962 9cy, September 20 2003, IJmuiden, the Netherlands.
Lesser Black-backed Gull intermedius NOS 4196376 17cy, September 23 2010, Westkapelle, the Netherlands.
Lesser Black-backed Gull intermedius NOS 4209546 6CY, September 22 2002, Le Portel, France.
Lesser Black-backed Gull intermedius NOS 4241800 8CY, September 11 2010, Boulogne sur mer, NW France. Picture: Jean-Michel Sauvage.
Lesser Black-backed Gull (intermedius) NOO NA08330 26CY, September 17 2016, Boulogne-sur-Mer, France (50.44 N - 01.35 E). Picture Jean-Michel Sauvage.
Lesser Black-backed Gull intermedius NOO NA11199 adult, September 19 2003, IJmuiden, the Netherlands..
Lesser Black-backed Gull intermedius SVS 8362147 adult, September 20 2003, IJmuiden, the Netherlands.
Lesser Black-backed Gull intermedius SVS 8101867 adult, September 20 2003, IJmuiden, the Netherlands. Probably from Sweden.
Lesser Black-backed Gull intermedius SVS 8099xxx adult, September 26 2003, IJmuiden, the Netherlands.
Lesser Black-backed Gull intermedius SVS 8081117 18CY, September 23 2010, Westkapelle, the Netherlands. 
Lesser Black-backed Gull intermedius SVS 8074511 26CY, September 30 2016, Westkapelle, the Netherlands. .
Lesser Black-backed Gull M:011 adult, September - November 2016, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull M:012 adult, September 08 2015, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii M:135 adult, September 06 2017, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii M:165 adult, September 06 2017, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii M:166 adult, September 06 2017, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii F122 adult, September 16 2016, Matosinhos Beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull F961 adult, September 26 2017, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii X:01 adult, September 12 2017, Matosinhos beach, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii N0LR adult, September 16 2016, Leixões harbour, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull graellsii N509 15CY, September 29 2015, Leixoes harbour, Matosinhos, Portugal. Picture: José Marques.
Lesser Black-backed Gull ESI 6151979 adult, September 30 2016, Westkapelle, the Netherlands. .
Lesser Black-backed Gull adult, September 19 2013, Katwijk, the Netherlands.
Lesser Black-backed Gull adult, September 17 2013, Katwijk, the Netherlands.
Lesser Black-backed Gull adult, September 17 2013, Katwijk, the Netherlands.
Lesser Black-backed Gull adult, September 08 2013, Katwijk, the Netherlands.
Lesser Black-backed Gull adult, September 25 2012, Katwijk, the Netherlands.
Lesser Black-backed Gull adult, September 28 2012, Katwijk, the Netherlands.
Lesser Black-backed Gull adult, September 25 2012, Katwijk, the Netherlands.
Lesser Black-backed Gull adult, September 19 2013, Katwijk, the Netherlands.
Lesser Black-backed Gull adult, September 26 2013, Katwijk, the Netherlands.
Lesser Black-backed Gull adult, September 23 2013, Katwijk, the Netherlands.
Lesser Black-backed Gull graellsii adult, September 04 2015, Utrecht, the Netherlands.
Lesser Black-backed Gull adult, September 07 2015, Katwijk, the Netherlands.
Lesser Black-backed Gull graellsii adult, September 04 2015, Utrecht, the Netherlands.
Lesser Black-backed Gull graellsii adult, September 04 2015, Utrecht, the Netherlands.
Lesser Black-backed Gull graellsii adult, September 04 2015, Utrecht, the Netherlands.
Lesser Black-backed Gull adult, September 19 2013, Katwijk, the Netherlands.
Lesser Black-backed Gull adult, September 25 2012, Katwijk, the Netherlands.
Photo 1: LBBG adult, September 30 2001, Le Portel, France.