Herring Gull- Zilvermeeuw (argentatus & argenteus)

(last update: December 15, 2011 )

Herring Gull adults March

Introduction

This website deals with the Herring Gulls of the taxa argentatus and argenteus. Argenteus is an abundant breeding species on Iceland, Britain, NW France, Belgium, the Netherlands and N Germany. The taxon argentatus breeds in NE Europe, from Denmark, the coast of the Baltic Sea, Scandinavia and coast of the White Sea. In the centre of the breeding range (Denmark and the NW German coast), birds show intermediate characteristics, indicating there is a cline in argenteus-argentatus. Argenteus in Western Europe is pale-backed, slightly smaller and with relatively much black in the wing-tip; argentatus in the NE Europe is larger, slightly darker on upper-parts and show less black in the wing-tip.
Due to the large breeding range, there is much intra-specific variation in argentatus, with most large, powerful birds in the northern populations, showing the most darkest upper-parts, longest wing and most white in the outer-wing. In this region, some populations may hold substantial number of yellow-legged argentatus. (referred to as "Finnmark yellow-legged argentatus"). In adult plumage, the black sub-terminal spot on P5 is often lacking or strongly reduced to a diffuse streak, broken at the centre. Sometimes P6 lacks black as well. 
In the Baltic region, other yellow-legged argentatus populations occur ("Baltic yellow-legged argentatus"), with adults showing even brighter yellow legs in summer and the upper-parts only slightly darker than West European argenteus, still much paler than Yellow-legged Gull (michahellis). Those Baltic argentatus often show a black sub-terminal spot on P5 in adult plumage.
On these web-pages, we largely follow P.J. Grant: "Gulls, a guide to identification" and E.K Barth's publication as Contribution No. 86, Zoological Museum, University of Oslo: "The circumpolar systematics of Larus argentatus and Larus fuscus with special reference to the Norwegian populations".

adult Herring Gulls - primary pattern

The differences between typical western argenteus from the U.K. and northern Scandinavian argentatus is rather straightforward on primary pattern P5-P10. However, there is a gradient and overlap in features of birds from populations in northern Germany, Denmark and southern Norway. 
Identification is even more challenging in birds from Baltic populations, which show both characteristics of argenteus and argentatus, but sometimes also of the southern taxa michahellis and particularly cachinnans.
Adult birds from the western populations argenteus show more black in the outer primaries, compared to northern argentatus. In argenteus, P5 normally shows small black sub-terminal markings, concentrated on the outer-web as a clear-cut black angular spot and in some birds extending on the inner-web as a diffuse streak. There may be some black on P4 as well, although this might be a clue for near-adult birds. In argentatus, especially from far northern Scandinavia, the black marking on P5 is completely lacking or is very limited and diffuse.
Argenteus
often has a black sub-terminal band on the top of P10, dividing the tip from the mirror. If the black sub-terminal band on P10 is broken, there is often still black on the inner and outer-web's edge of P10. Normally argentatus lacks sub-terminal markings on the outer-web of P10.

Baltic argentatus often have the black marking on P5 confined to the outer-web as a single rectangular small black square, with well-defined borders (not diffuse as in most Finnmark birds). In most Baltic birds, the white tip of P10 fully merges with the mirror, without a single sign of a sub-terminal band. The greyish-white 'tongue' on the inner-web is often broad and continues far down P10, almost creating a thayeri pattern on P10. The shape of the division line between greyish tongue and black outer-web can be an identification clue: In cachinnans this division line often makes a strong angular curve and has a smooth straight line, unlike the pattern of Herring Gulls, which often show a "saw-blade" motive or otherwise much irregularities along the division line. Sometimes wear of the outer primaries may be useful as a first indication of origin: An early moulting species as cachinnans on average show more abrasion in the feathers than later moulting argentatus.

Extensive research on the P10 pattern of Scandinavian argentatus was done for Norwegian birds by the Norwegian ornithologist Edvard Barth, and is presented in the table below. 

Table 4 from E.K. Barth, The circumpolar systematics of Larus argentatus and Larus fuscus with special reference to the Norwegian populations, 1968. 200 Norwegian birds. (Notation converted to what we use in the texts, MM).
locality sample size tip pattern P10 tip pattern P9 colour of P10 inner-web black present from P10 to:
1 2 3 4 1 2 3 4 5 1 2 3 5 6 P7 P6 P5 P4
East Finnmark 15 n 10 1 2 2 5 4 1 1 4 5 7 3 12 3 - 10 5 -
% 67 7 13 13 33 27 7 7 27 33 47 20 80 20 - 67 33 -
Tamsöy in Central Finnmark 33 n 17 7 6 3 10 10 6 0 7 12 20 1 23 10 - 19 13 1
% 52 21 18 9 30 30 18 - 21 36 61 3 70 30 - 58 39 -
Troms 29 n 17 8 3 1 11 9 4 1 4 3 20 6 24 5 - 24 5 -
% 59 28 10 3 38 31 14 3 14 10 69 21 83 17 - 83 17 -
Bodö and Röst 32 n 15 10 3 2 19 3 5 0 3 3 24 5 27 5 1 18 13 -
% 50 33 10 7 63 10 17 - 10 9 75 16 84 16 3 56 41 -
Tarva 20 n 8 7 3 2 11 5 4 0 0 10 8 2 12 8 1 7 10 2
% 40 35 15 10 55 25 20 - - 50 40 10 60 40 5 35 50 10
Stavanger and Lindesnes 42 n 18 13 4 6 23 12 3 2 2 15 23 4 37 5 - 13 29 -
% 44 32 10 14 55 28 7 5 5 36 55 9 88 12 - 31 69 -
Oslo Fiord 29 n 19 6 3 1 20 1 4 1 2 12 14 3 24 5 - 17 12 -
% 66 21 10 3 71 4 14 4 7 42 48 10 83 17 - 59 41 -
.
1: all white
2: trace of black near tip
3: incomplete black bar near tip
4: complete black bar or black tip
1: broad white band over both webs
2: white spot on both webs
3: white spot on inner web only
4: no white spot present
5: 'thayeri-pattern'
1: like mantle colour
2: slightly lighter than mantle colour
3: markedly lighter than mantle colour
5: relatively sharp border between black and grey
6: gradual transition from black to grey

Especially birds from north Scandinavian Finnmark may show the characteristic 'thayeri' pattern in the outer primaries P9 and P10 (column 5 of tip pattern P9 in the table). This pattern is named after the Thayer's Gull, which often shows a particular pattern in the outer primaries: the mirror and the white tip merge and are connected to the pale inner-web (see this image). In other words: the black medial band of the outer-web doesn't fully reach the edge of the inner-web and there is no sub-terminal band. In Thayer's Gull this pattern may be very obvious and, together with the 'string of pearls' may be indicative for identification. 

Primary moult timing and strategy

By October the majority of adult Lesser Black-backed Gulls moulting the outer primaries. There is a clear difference between presumed birds lingering around and birds which will probably migrate further south quickly. The difference can be found in the primary moult strategy. 

Some adult have a large moulting gap in the central primaries (for example P8-P10 old and only P4 fully grown and P5 still slightly shorter than P4) by the first days of September. It is hard to believe these birds will travel large distances non-stop as such moult gaps are highly inefficient for this migration pattern. Probably these birds, which can be found moulting in a period roughly from late August to late November stay in the area throughout their primary moult. They migrate further south either forced by cold winter or when the primaries moult arrives at the far outer primaries.

The other group is represented by birds with a very small moult gap in the primaries or with a very low primary moult score, indicating that primary moult will probably suspended until arrival at the wintering grounds. 

Tables & Graph

remaining SPRING

 

 

 

 

 

 

 

starting date:

 30 Apr

 07 May

14 May

21 May

04 Jun

11 Jun

30 Jul

week no:

18

19

20

21

23

24

31

0

0

0

0

0

 

 

0

1

0

0

0

0

 

 

0

2

0

0

0

0

 

 

1

3

0

0

0

0

 

 

1

4

0

0

0

0

 

 

37

5

0

0

0

0

 

 

22

6

0

0

0

0

 

 

3

7

3

2

1

2

 

 

0

8

16

22

26

18

1

1

0

9

30

13

16

10

1

 

0

10

66

33

37

10

 

 

0

 

 

 

 

 

 

 

 

n=

115

70

80

40

2

1

64

average REM P:

9.4

9.1

9.1

8.7

8.5

8.0

4.4

95% CID =

0.15

0.23

0.20

0.29

6.35

 

0.17

inverse =

1.98

1.99

1.99

2.02

12.71

 

2.00

Variantie (s2) =

0.68

0.90

0.84

0.83

0.50

 

0.46

SD (s) =

0.82

0.95

0.91

0.91

0.71

 

0.68

SE (sx) =

0.08

0.11

0.10

0.14

0.50

 

0.09

 

 

 

 

 

 

 

 

% class:

 

 

 

 

 

 

 

0

0

0

0

0

0

0

0

1

0

0

0

0

0

0

0

2

0

0

0

0

0

0

2

3

0

0

0

0

0

0

2

4

0

0

0

0

0

0

58

5

0

0

0

0

0

0

34

6

0

0

0

0

0

0

5

7

3

3

1

5

0

0

0

8

14

31

33

45

50

100

0

9

26

19

20

25

50

0

0

10

57

47

46

25

0

0

0

 

 

 

 

 

 

 

 

% control:

100

100

100

100

100

100

100

  Table above, data for the Netherlands (2000-2010), results for spring & summer (aggregated week): number of remaining old primaries in adults.
0 = 0 old primaries left (P10 dropped); 10 = all 10 primaries still old and present.

Above: Scatter Plot for PMS in adult Herring Gulls. Number of remaining old primaries throughout the year. Sample size is 1.329 birds.

new: SPRING

 

 

 

 

starting date:

 30 Apr

07 May 

14 May 

21 May 

week no:

18

19

20

21

0

104

60

66

30

1

7

9

12

7

2

4

1

2

3

3

0

0

0

0

4

0

0

0

0

5

0

0

0

0

6

0

0

0

0

7

0

0

0

0

8

0

0

0

0

9

0

0

0

0

10

0

0

0

0

 

 

 

 

 

n=

115

70

80

40

average NEW P:

0.1

0.2

0.2

0.3

95% CID =

0.08

0.10

0.10

0.20

inverse =

1.98

1.99

1.99

2.02

Variantie (s2) =

0.18

0.16

0.21

0.38

SD (s) =

0.43

0.40

0.46

0.62

SE (sx) =

0.04

0.05

0.05

0.10

 

 

 

 

 

% class:

 

 

 

 

0

90

86

83

75

1

6

13

15

18

2

3

1

3

8

3

0

0

0

0

4

0

0

0

0

5

0

0

0

0

6

0

0

0

0

7

0

0

0

0

8

0

0

0

0

9

0

0

0

0

10

0

0

0

0

 

 

 

 

 

% control:

100

100

100

100

  Table above, data for the Netherlands (2000-2010), results for spring & summer (aggregated week): number of new, fully grown primaries in adults.
0 = no new primaries visible. So either P1 still old, or P1 dropped, but the very tip still not visible.
1 = P1 longest new primary. Range between "at least the tip of P1 is visible" until "tip of P2 still shorter than P1".
2 = P2 longest new primary. 3 = etc.

Above: Scatter Plot for PMS in adult Herring Gulls throughout the year. Longest new primary is classified "fully grown". Sample size is 3.271 birds. Birds scored on NEW primaries.

The first date in our analysis on adult Herring Gulls is 02 May 2006 (week 18 - starting 30 April), on which we already found birds with missing primaries (some birds had already shed 3 primaries). This group of actively moulting birds, 43% of the sample, must have started the complete moult somewhere around mid-April and probably several birds may have started earlier.

The last scoring day has been 03 December, when still 20% of the sampled birds had to grow P10. The final stage of the complete moult for all birds has to be somewhere after mid-December. On 03 December we scored 59 birds with P10 fully grown, 13 birds with P9 fully grown and 2 birds with P8 fully grown. They all had no old primaries left.

The first time a new primary (P1) was visible, was also on 02 May 2006 (week 18 - starting 30 April). In this week, 90% of the sample did not show new primaries, but 9% did. Four birds in the sample of 115 birds alreday had P2 as longest primary (fully grown). As soon as the tip of P1 was visible, this was automatically scored "fully grown", and this was the case in 7 birds. 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).

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 = 1329, R2= 0.935, sign: P<0,000)
PMS = -0,379* WEEK + 16,324.

LINEAR REGRESSION FOR NEW FULLY GROWN PRIMARIES

Complete sample: Linear regression (n = 3271 R2= 0.927, sign: P<0,000)
PMS = 0,322* WEEK - 6,071.

below: some adult Herring Gulls in March.

 

 

rings argenteus: U.K.
2cy argentatus in February, ringed in Norway. (75189 bytes)Herring Gull argenteus BTO GC89751 adult, March 2015, Scheveningen Haven, the Netherlands. Picture: Merijn Loeve.
rings argenteus: France
Herring GullHerring Gull DA196843 16cy (argenteus), March 27 2011, Boulogne/Mer, France. Picture: J-M Sauvage.
Herring GullHerring Gull DA208394 17+cy (argenteus), March 31 2012, Boulogne-sur-Mer, NW France. Picture: Jean-Michel Sauvage.
Herring GullHerring Gull EA594518 adult (argenteus), June 2011 & March 2014, Boulogne/Mer, France. Picture: J-M Sauvage.
rings argenteus: Belgium
Herring GullGull (argenteus) CHAK 4CY-5CY (4th cycle), December 2011 & March 2012, Koksijde, Belgium. Picture: Peter Adriaens. 
Herring GullHerring Gull (argenteus) 6CY-8CY CKAL March 2013 & May 2015, Calais, NW France. Picture: Jean-Michel Sauvage.
adult argentatus in November, ringed in Estonia. (42082 bytes)Herring Gull (argenteus) FAAT 2CY & 6CY, February 2007 & March 2011, Belgium. Pictures Ies Meulmeester & Peter Adriaens. 
2cy argentatus in February, ringed in Norway. (75189 bytes)Herring Gull (argenteus) FGAF 5CY (4th cycle), March 05 2010, Nieuwpoort, Belgium. Picture: Peter Adriaens.
2cy argentatus in February, ringed in Norway. (75189 bytes)Herring Gull (argenteus) FXAM 5CY (4th cycle), March 05 2010, Koksijde, Belgium. Picture: Peter Adriaens.
2cy argentatus in February, ringed in Norway. (75189 bytes)Herring Gull (argenteus) FXAP 5CY (4th cycle), March 10 2011, Blaringhem, France. Picture: Harry J.P. Vercruijsse.
Herring GullHerring Gull GDAV 5-6cy (argenteus), March 2011 & April 2012, Boulogne/Mer, France. Picture: J-M Sauvage.
adult argentatus in November, ringed in Estonia. (42082 bytes)Herring Gull (argenteus) KSAJ adult, April 2010, March 2011 & December 2012, Koksijde, Belgium. Picture: Peter Adriaens. 
Herring GullHerring Gull (argenteus) 15CY KTAF March 30 2013, Calais, NW France. Picture: Jean-Michel Sauvage.
2cy argentatus in February, ringed in Norway. (75189 bytes)Herring Gull (argenteus) MMAK adult, January 10 - March 10 2011, Koksijde, Belgium. Picture: Peter Adriaens. 
Herring GullHerring Gull H128166 10cy (argenteus), March 2011 & 2012, Boulogne/Mer, France. Picture: J-M Sauvage.
rings argenteus: the Netherlands
1cy argenteus in August, ringed in Belgium. (90559 bytes)Herring Gull Y.AFL adult (argenteus), March 2010 & September 2011, IJmuiden, the Netherlands.
1cy argenteus in August, ringed in Belgium. (90559 bytes)Herring Gull Y.AHA adult (argenteus), March 04 2011, IJmuiden, the Netherlands.
1cy argenteus in August, ringed in Belgium. (90559 bytes)Herring Gull Y.AHB adult (argenteus), 2010 - 2011, IJmuiden, the Netherlands.
1cy argenteus in August, ringed in Belgium. (90559 bytes)Herring Gull Y.AJP 23cy (argenteus), 2002 - 2010, IJmuiden, the Netherlands. Formerly J=, now partner of Y.AHB.
1cy argenteus in August, ringed in Belgium. (90559 bytes)Herring Gull Y.AKS adult argenteus), 2009 - 2010, IJmuiden, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull (argenteus) adult YBAN March 30 2013, Voorhout, the Netherlands.
1cy argenteus in August, ringed in Belgium. (90559 bytes)Herring Gull (argenteus) YBAX adult, April 2015 - March 2016, IJmuiden, the Netherlands. 
3cy argentatus in January. (80207 bytes)Herring Gull (argenteus) adult YBBH March 30 2013, Voorhout, the Netherlands.
1cy argenteus in August, ringed in Belgium. (90559 bytes)Herring Gull KNAT 8+cy (argenteus), 2010-2011, Leiden, the Netherlands.
Herring GullHerring Gull (argenteus) MAVV adult, March 02 2016, Barneveld, the Netherlands.
probable hybrid argenteus x michahellis 4cy in April. (85911 bytes)hybrid argenteus x michahellis PA 11cy,March 10 2007, Neeltje Jans, the Netherlands.
2cy argentatus in February, ringed in Norway. (75189 bytes)Herring Gull (argenteus) V0 5CY (4th cycle), March 07 2010, Visé, Belgium. Picture: Peter Adriaens.
2cy argentatus in February, ringed in Norway. (75189 bytes)Herring Gull (argenteus) 11 5CY (4th cycle), March 26 2011, Koksijde, Belgium. Picture: Peter Adriaens.
Herring GullHerring Gull (argenteus) UT 7CY, January - August 2014, Dordrecht, the Netherlands. Picture: Theo Muusse & Merijn Loeve.
2cy argentatus in February, ringed in Norway. (75189 bytes)Herring Gull (argenteus) YB 4CY-5CY (3rd - 4th cycle), March 2011 & March 2012, Koksijde, Belgium. Picture: Peter Adriaens. 
Herring GullHerring Gull P8 (argenteus), February-March 2008, Dordrecht, the Netherlands.
3cy argenteus in May, ringed in Belgium. (71617 bytes) Herring Gull argenteus JB adult, August 2015, May 2016 - May 2017, Katwijk, the Netherlands.
Herring GullHerring Gull (argenteus) ZS adult, October 2015 - March 2016, Scheveningen, the Netherlands.
2cy argentatus in February, ringed in Norway. (75189 bytes)Herring Gull (argenteus) T.R 4CY-7CY, April 2016, May-June 2017 & March 2019, Katwijk, the Netherlands.
Herring GullHerring Gull DA 24-27cy (argenteus, 2009-2010, Leiden, Netherlands.
1cy argenteus in August, ringed in Belgium. (90559 bytes)Herring Gull E261 adult (argenteus), March 13 2010, Leiden, the Netherlands. Picture: Maarten van Kleinwee.
adult argenteus in March, ringed in the Netherlands. (110654 bytes)Herring Gull 5.281.170 5cy (argenteus), March 10 2004, Brouwersdam, the Netherlands (51.45N 03.52E). Picture by Pim Wolf.
3cy argenteus in May, ringed in Belgium. (71617 bytes) Herring Gull argenteus NLA 5.352.687 13CY, 16CY & 17CY, November 2013 & May 2016 - April 2017, Katwijk aan Zee, the Netherlands.
1cy argenteus in August, ringed in Belgium. (90559 bytes)Herring Gull NLA.5.352.700 12cy (argenteus), March 2012, Scheveningen, the Netherlands.
1cy argenteus in August, ringed in Belgium. (90559 bytes)Herring Gull NLA.5.352.764 9cy (argenteus), March 2010 & 2011, IJmuiden, the Netherlands.
adult argenteus in March, ringed in the Netherlands. (67819 bytes)Herring Gull 5.359.457 adult (argenteus), March 18 2002, Missouriweg, Maasvlakte, the Netherlands (51.59N 04.02E). Ringed February 01 2002 at Westduinen, Den Haag as near-adult (at least older than 3cy).
adult argenteus in March, ringed in the Netherlands. (123289 bytes)Herring Gull (argenteus) NLA 5.361.238 5CY & 16CY, March 2004 & October 2015, Brouwersdam, the Netherlands.
5cy argenteus in March, ringed in the Netherlands. (78422 bytes)Herring Gull 5.366.547 5cy (argenteus), March 29 2004, Westkapelle, the Netherlands (51.33N 03.25E). Picture Pim Wolf.
1cy argenteus in August, ringed in Belgium. (90559 bytes)Herring Gull NLA.5.413.555 7cy (argenteus), March 04 2011, IJmuiden, the Netherlands.
1cy argenteus in August, ringed in Belgium. (90559 bytes)Herring Gull NLA.5.414.557 adult (argenteus), March 13 2010, Leiden, the Netherlands. Picture: Maarten van Kleinwee.
1cy argenteus in August, ringed in Belgium. (90559 bytes)Herring Gull NLA.5.419.235 5cy (argenteus), March 27 2010, Leiden, the Netherlands. Picture: Maarten van Kleinwee.
Herring GullHerring Gull argenteus 6.125.871 5CY & 8CY, August 2012 & March 2015, IJmuiden, the Netherlands.
Herring GullHerring Gull argenteus NLA 6.168.143 8CY-9CY, February 2018 & March 2019, Katwijk, the Netherlands.
rings argentatus: Norway
Herring GullHerring Gull (argentatus) J1465 6CY, March 16 2016, Katwijk, the Netherlands.
Herring GullHerring Gull (argentatus) J5858 adult, March 04 2015, Hovindam - Oslo, Norway. Picture: John Sandøy.
rings argentatus: Lithuania
Herring GullHerring Gull (argentatus) LIK EN03.615 & 9L5B sub-adult (5CY), March 08 2015, Jakuševec landfill, Zagreb, Croatia. Picture: ringing team Luka Jurinovic.
Herring GullHerring Gull argentatus 9L9B adult, March 18 2014, Zabieliškis - Kaunas, Lithuania. Picture: Boris Belchev.
rings argentatus:  Russia
Herring GullHerring Gull argentatus KF01 7CY, March 09 2016, Den Haag, the Netherlands. Picture: Merijn Loeve.
Herring GullHerring Gull argentatus KH89 January - September 2010, October 2011 & March 2015, the Netherlands & France.

1cy argenteus in August, ringed in Belgium. (90559 bytes)Herring Gull (argentatus) RUM C-730262 6CY-7CY, January - February 2018 & March 2019, Katwijk, the Netherlands. 
unringed adult Herring Gulls
1cy argenteus in August, ringed in Belgium. (90559 bytes)Herring Gull hybride (argentatus), March 19 2010, IJmuiden, the Netherlands.
1cy argenteus in August, ringed in Belgium. (90559 bytes)Herring Gull adult, March 21 2016, IJmuiden, the Netherlands.
1cy argenteus in August, ringed in Belgium. (90559 bytes)Herring Gull adult, March 21 2016, IJmuiden, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull (argentatus) adult, March 10 2014, Katwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull (argentatus) adult, March 10 2014, Katwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull (argentatus) adult, March 05 2014, Katwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull (argentatus) adult, March 30 2013, Voorhout, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, March 30 2016, Katwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, March 30 2016, Katwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, March 30 2016, Katwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, March 30 2016, Katwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, March 30 2016, Katwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, March 30 2016, Katwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, March 30 2016, Katwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, March 30 2016, Katwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, March 30 2016, Katwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, March 30 2016, Katwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, March 30 2016, Katwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, March 30 2016, Katwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, March 30 2016, Katwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, March 30 2016, Katwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, March 30 2016, Katwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, March 30 2016, Katwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, March 05 2014, Katwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull 5CY, March 10 2014, Katwijk, the Netherlands. No mirror on P10.
3cy argentatus in January. (80207 bytes)Herring Gull adult, March 21 2013, Noordwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, March 21 2013, Noordwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, March 21 2013, Noordwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, March 21 2013, Noordwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, March 13 2013, Noordwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, March 13 2013, Noordwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, March 13 2013, Noordwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, March 13 2013, Noordwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, March 13 2013, Noordwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, March 13 2013, Noordwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, March 13 2013, Noordwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, March 13 2013, Noordwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull near-adult / 5cy, March 09 2012, Scheveningen, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, March 01 2014, Katwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, March 01 2014, Katwijk, the Netherlands.
adult argenteus in March. (50688 bytes)Herring Gull adult (argenteus), March 16 2003, Boulogne/Mer, France (50.42 N,1.34E). Illustrative example for NW French birds.
adult argenteus in March. (65745 bytes)Herring Gull adult (argenteus), March 17 2003, Boulogne/Mer, France (50.42N 01.34E).
adult argenteus in March. (62156 bytes)Herring Gull adult (argenteus), March 17 2003, Boulogne/Mer, France (50.42N 01.34E).