Herring Gull- Zilvermeeuw (argentatus & argenteus)

(last update: December 15, 2011 )

Herring Gull adults May

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".

breeding Herring Gulls at Moerdijk

Continental European Herring Gull L. a. argenteus are known to show phenotypic characteristics which are intermediate between their British (L. a. argenteus) and Scandinavian relatives (L. a. argentatus). However, nothing has been published to date on the moult pattern and detailed phenotype of birds breeding in the Netherlands.

The industrial complex Moerdijk in the Netherlands holds a mixed colony of Herring and Lesser Black-backed Gulls. Colonisation of Moerdijk started in the early 1980s. By 2006, an estimated 650 pairs of Herring Gulls and 2900 pairs of Lesser Black-backed Gulls bred in the colony. In 2005, 157 breeding Herring Gulls and 434 Lesser Black-backed Gulls were colour ringed at Moerdijk, with 158 and 604, respectively, ringed in 2006.

We used these data collected at Moerdijk to describe the phenotypic characteristics and commencement of primary moult. Our data illustrate the large intra-population variability that exists for these taxa, even within a single colony. We discuss the implications of this variability for field identification of the various sub-species of Herring and Lesser Black-backed Gulls on this website.

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.

rings argenteus: UK
adult argenteus in October, ringed in the Netherlands. (35116 bytes)Herring Gull PS1T adult (argenteus), May 06 2012, Boulogne-sur-Mer, NW France. Picture: Jean-Michel Sauvage.
rings argenteus: France
2cy argenteus in March, ringed in France. (57822 bytes)Herring Gull MAA adult (argenteus), April-May 2012, Boulogne/Mer, France (50.42N,1.34E). Picture: J-M Sauvage.
2cy argenteus in March, ringed in France. (57822 bytes)Herring Gull UZA adult (argenteus), May 04 2012, Calais, France (50.42N,1.34E). Picture: J-M Sauvage.
2cy argenteus in March, ringed in France. (57822 bytes)Herring Gull (argenteus) 5CY VPA May 18 2013, Calais, NW France. Picture: Jean-Michel Sauvage.
rings argenteus: Belgium
adult argenteus in May, ringed in Belgium. (66065 bytes)Herring Gull 8+cy AAAA (argenteus), May 03 2003, Voorhaven, Zeebrugge, Belgium (51.59N 04.02E).
adult argenteus in May, ringed in Belgium. (64855 bytes)Herring Gull 7+cy BUAH (argenteus), May 03 2003, Voorhaven, Zeebrugge, Belgium (51.59N 04.02E).
adult argenteus in October, ringed in the Netherlands. (35116 bytes) Herring Gull (argenteus) H-131757 11CY, May 11 2014, Boulogne-sur-Mer, NW France. Picture: Jean-Michel Sauvage.
adult argenteus in October, ringed in the Netherlands. (35116 bytes)Herring Gull H-132860 adult (argenteus), April-July 19 2012, Calais, France. Picture: J-M Sauvage.
2cy argenteus in March, ringed in France. (57822 bytes)Herring Gull H133694 adult (argenteus), May & June 2010, Leiden, Netherlands.
2cy argentatus in Jan-Febr, ringed in Russia.Herring Gull adult H-137233 (argenteus) August - September 2012 & May 2014, Katwijk, the Netherlands.
rings argenteus: 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.AHC adult (argenteus), May 06 2011, IJmuiden, the Netherlands.
1cy argenteus in August, ringed in Belgium. (90559 bytes)Herring Gull M.AAP adult (argenteus), May 07 2011, Texel, the Netherlands.
1cy argenteus in August, ringed in Belgium. (90559 bytes)Herring Gull M.ACZ adult (argenteus), May & June 2011, Texel, the Netherlands.
1cy argenteus in August, ringed in Belgium. (90559 bytes)Herring Gull F.AAN adult (argenteus), May 07 2011, Texel, the Netherlands.
1cy argenteus in August, ringed in Belgium. (90559 bytes)Herring Gull F.ADC adult (argenteus), May 07 2011, Texel, the Netherlands.
1cy argenteus in August, ringed in Belgium. (90559 bytes)Herring Gull F.AFN adult (argenteus), May 07 2011, Texel, the Netherlands.
1cy argenteus in August, ringed in Belgium. (90559 bytes)Herring Gull F.AHK adult (argenteus),May & June 2011, Texel, the Netherlands.
2cy argenteus in March, ringed in France. (57822 bytes)Herring Gull DA 24-27cy (argenteus, 2009-2010, Leiden, Netherlands.
1cy argenteus in August, ringed in Belgium. (90559 bytes)Herring Gull NLA.5.352.764 10cy (argenteus), May 2011, IJmuiden, the Netherlands. Seen in eight years now.
1cy argenteus in August, ringed in Belgium. (90559 bytes)Herring Gull NLA.5.344.303 12cy (argenteus), May 06 2011, IJmuiden, the Netherlands.
adult argenteus in August, ringed in Belgium. (86047 bytes)Herring Gull NLA 5.335.x52 adult (argenteus), May 06 2007, IJmuiden, the Netherlands.
Yellowish legs.
2cy argenteus in March, ringed in France. (57822 bytes)Herring Gull 5.419.235 5cy (argenteus), 2010-2011, Leiden, Netherlands.
Herring Gull PL 24cy female (argenteus), 07 May 2006. Breeding bird at Moerdijk, Netherlands.
probable hybrid argenteus x michahellis 4cy in April. (85911 bytes)hybrid PA 11cy (argenteus x michahellis), May 06 2007, Neeltje Jans, the Netherlands.
Herring Gull S0 19cy male (argenteus), 06 May 2005. Breeding bird at Moerdijk, Netherlands.
Herring Gull 1A 17cy female (argenteus), 04 May 2005. Breeding bird at Moerdijk, Netherlands.
Herring Gull VE 14-15cy (argenteus), 21 May 2005 & 16 May 2006. Breeding bird at Moerdijk, Netherlands.
Herring Gull C0 14cy female (argenteus), 06 May 2005. Breeding bird at Moerdijk, Netherlands.
Herring Gull 10 13cy male (argenteus), 05 May 2005. Breeding bird at Moerdijk, Netherlands.
Herring Gull JK 11cy male (argenteus), 05 May 2006. Breeding bird at Moerdijk, Netherlands.
Herring Gull HL 11cy female (argenteus), 04 May 2006. Breeding bird at Moerdijk, Netherlands.
Herring Gull H2 11cy male (argenteus), 05 May 2006. Breeding bird at Moerdijk, Netherlands.
Herring Gull KL 10cy male (argenteus), 09 May 2006. Breeding bird at Moerdijk, Netherlands.
Herring Gull LN 9cy male (argenteus), 13 May 2006. Breeding bird at Moerdijk, Netherlands.
Herring Gull P3 9cy male (argenteus), 16 May 2005. Breeding bird at Moerdijk, Netherlands.
Herring Gull 64 9cy male (argenteus), 21 May 2005. Breeding bird at Moerdijk, Netherlands.
Herring Gull NE 8cy male (argenteus), 16 May 2006. Breeding bird at Moerdijk, Netherlands.
Herring Gull JX 8cy male (argenteus), 06 May 2006. Breeding bird at Moerdijk, Netherlands.
Herring Gull KU 8cy male (argenteus), 09 May 2006. Breeding bird at Moerdijk, Netherlands.
Herring Gull 59 8cy female (argenteus), 21 May 2005. Breeding bird at Moerdijk, Netherlands.
Herring Gull 2Z 8cy male (argenteus), 06 May 2005. Breeding bird at Moerdijk, Netherlands.
Herring Gull K2 7cy (argenteus), 09 May 2006. Breeding bird at Moerdijk, Netherlands.
Herring Gull 4T 7cy female (argenteus), 16 May 2005. Breeding bird at Moerdijk, Netherlands.
Herring Gull 42 7cy female (argenteus), 16 May 2005. Breeding bird at Moerdijk, Netherlands.
Herring Gull 18 7cy male (argenteus), 05 May 2005. Breeding bird at Moerdijk, Netherlands.
Herring Gull 3E 7cy female (argenteus), 14 May 2005. Breeding bird at Moerdijk, Netherlands.
Herring Gull K4 6cy male (argenteus), 09 May 2006. Breeding bird at Moerdijk, Netherlands.
Herring Gull J7 6cy male (argenteus), 09 May 2006. Breeding bird at Moerdijk, Netherlands.
Herring Gull 3T 6cy (argenteus), 14 May 2005. Breeding bird at Moerdijk, Netherlands.
probable hybrid argenteus x michahellis 4cy in April. (85911 bytes)hybrid PA 10cy (argenteus x michahellis), May 07 2006, Neeltje Jans, the Netherlands.
unringed adult Herring Gulls
3cy argentatus in January. (80207 bytes)Herring Gull argentatus adult, May 17 2009, Tarastenjärvi dump - Tampere, Finland. Picture: Visa Rauste.
2cy argentatus in Jan-Febr, ringed in Russia.Herring Gull argenteus adult, May 11 2014, Boulogne-sur-Mer, NW France. Picture: Jean-Michel Sauvage.
adult argenteus in May. (95353 bytes)Herring Gull (argenteus), May 03 2003, Voorhaven, Zeebrugge, Belgium (51.59N 04.02E).
2cy argentatus in Jan-Febr, ringed in Russia.Herring Gull argenteus adult, May 20 2014, Katwijk, the Netherlands.
2cy argentatus in Jan-Febr, ringed in Russia.Herring Gull argenteus adult, May 20 2014, Katwijk, the Netherlands.
2cy argentatus in Jan-Febr, ringed in Russia.Herring Gull argenteus adult, May 13 2014, Katwijk, the Netherlands.
2cy argentatus in Jan-Febr, ringed in Russia.Herring Gull argenteus adult, May 13 2014, Katwijk, the Netherlands.
2cy argentatus in Jan-Febr, ringed in Russia.Herring Gull argenteus adult, May 13 2014, Katwijk, the Netherlands.
adult argenteus in May. (80555 bytes)Herring Gull adult (argenteus), May 12 2001, Westkapelle, the Netherlands (51.33N 03.25E). Picture by Pim Wolf.
adult argenteus in May. (72048 bytes)Herring Gull adult (argenteus), May 12 2002, Missouriweg, Maasvlakte, the Netherlands (51.59N 04.02E). Bird died last week.
adult argenteus in May. (46312 bytes)Herring Gull adult (argenteus), May 13 2002, Dintelhaven, Maasvlakte, the Netherlands (51.59N 04.02E). Bird died today.