Herring Gull- Zilvermeeuw (argentatus & argenteus)

(last update: December 15, 2011 )

Herring Gull adults October

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".

Tables & Graph

Adults are in active primary moult. The tables below present the primary moult stage by early and mid-October.

adult Herring Gull, primary moult score at Boulogne/Mer, NW France, October 05 2002.
  P9 old P10 old no old total old:
P6 new 8 13 7 28
P7 new 1 11 113 125
P8 new - - 48 48
P9 new - - 2 2
total new: 9 24 170 203

Notes:
1. adult birds identified by primary covert pattern and bare part coloration.
2. all birds present in the resting group scored.
3. P5...P8 new = the longest primary present in the folded wing, longer than the previous ranked primary, but remember this primary may not be fully grown in some birds.
4. new primaries: total (n) = 203; average (m) = 7.1; standard deviation (SD) = 0.63.
5. old primaries: total (n) = 203; average (m) = 9.8; standard deviation (SD) = 0.50.

 

adult Herring Gull, primary moult score at Scheveningen, the Netherlands, October 17 2002.
  P8 old P9 old P10 old no old total old:
P5 new 1 - - - 1
P6 new - 1 1 1 3
P7 new - 1 9 23 33
P8 new - - - 30 30
total new: 1 2 10 54 67

Notes:
1. adult birds identified by primary covert pattern and bare part coloration.
2. all birds present in the resting group scored.
3. P5...P8 new = the longest primary present in the folded wing, longer than the previous ranked primary, but remember this primary may not be fully grown in some birds.
4. new primaries: total (n) = 67; average (m) = 7.4; standard deviation (SD) = 0.65.
5. old primaries: total (n) = 67; average (m) = 9.8; standard deviation (SD) = 0.59.

Long term analysis for primary moult score (PMS).

remaining AUTUMN

 

 

 

 

 

 

 

 

 

starting date:

13 Aug

20 Aug

27 Aug

03 Sep

10 Sep

17 Sep

01 Oct

15 Oct

05 Nov

12 Nov

week no:

33

34

35

36

37

38

40

42

45

46

0

0

0

0

0

 

4

170

54

32

105

1

0

0

1

6

 

13

24

10

1

1

2

0

3

22

35

1

4

9

2

 

 

3

9

71

103

63

 

1

 

1

 

 

4

30

99

34

4

 

0

 

 

 

 

5

11

29

5

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

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

n=

50

202

165

108

1

22

203

67

33

106

average REM P:

4.0

3.8

3.1

2.6

2.0

1.1

0.2

0.3

0.0

0.0

95% CID =

0.18

0.10

0.11

0.12

 

0.33

0.07

0.14

0.06

0.02

inverse =

2.01

1.97

1.97

1.98

 

2.08

1.97

2.00

2.04

1.98

Variantie (s2) =

0.41

0.50

0.47

0.43

 

0.56

0.25

0.34

0.03

0.01

SD (s) =

0.64

0.71

0.69

0.65

 

0.75

0.50

0.59

0.17

0.10

SE (sx) =

0.09

0.05

0.05

0.06

 

0.16

0.04

0.07

0.03

0.01

 

 

 

 

 

 

 

 

 

 

 

% class:

 

 

 

 

 

 

 

 

 

 

0

0

0

0

0

0

18

84

81

97

99

1

0

0

1

6

0

59

12

15

3

1

2

0

1

13

32

100

18

4

3

0

0

3

18

35

62

58

0

5

0

1

0

0

4

60

49

21

4

0

0

0

0

0

0

5

22

14

3

0

0

0

0

0

0

0

6

0

0

0

0

0

0

0

0

0

0

7

0

0

0

0

0

0

0

0

0

0

8

0

0

0

0

0

0

0

0

0

0

9

0

0

0

0

0

0

0

0

0

0

10

0

0

0

0

0

0

0

0

0

0

 

 

 

 

 

 

 

 

 

 

 

% control:

100

100

100

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: AUTUMN

 

 

 

 

 

 

 

 

 

 

 

 

starting date:

17 Sep

24 Sep

01 Oct

08 Oct

15 Oct

22 Oct

29 Oct

05 Nov

12 Nov

19 Nov

26 Nov

03 Dec

week no:

38

39

40

41

42

43

44

45

46

47

48

49

0

0

0

0

0

0

 

 

0

0

 

0

 

1

0

0

0

0

0

 

 

0

0

 

0

 

2

3

0

0

0

0

 

 

0

0

 

0

 

3

1

0

0

0

0

 

 

0

0

 

0

 

4

10

0

0

0

0

 

 

0

0

 

0

 

5

98

26

2

1

1

 

 

0

0

 

0

 

6

138

100

127

9

4

 

1

0

0

 

0

 

7

44

55

391

175

65

24

10

2

20

 

0

 

8

6

1

104

98

83

87

71

54

222

31

20

2

9

0

0

3

4

4

18

23

49

256

60

76

13

10

0

0

0

0

0

 

3

15

39

36

222

59

 

 

 

 

 

 

 

 

 

 

 

 

 

n=

300

182

627

287

157

129

108

120

537

127

318

74

average NEW P:

5.7

6.2

7.0

7.3

7.5

8.0

8.2

8.6

8.6

9.0

9.6

9.8

95% CID =

0.10

0.10

0.05

0.07

0.10

0.10

0.13

0.13

0.06

0.13

0.07

0.11

inverse =

1.97

1.97

1.96

1.97

1.98

1.98

1.98

1.98

1.96

1.98

1.97

1.99

Variantie (s2) =

0.81

0.44

0.40

0.33

0.39

0.33

0.43

0.52

0.46

0.53

0.36

0.23

SD (s) =

0.90

0.66

0.63

0.58

0.63

0.57

0.66

0.72

0.68

0.73

0.60

0.48

SE (sx) =

0.05

0.05

0.03

0.03

0.05

0.05

0.06

0.07

0.03

0.06

0.03

0.06

 

 

 

 

 

 

 

 

 

 

 

 

 

% class:

 

 

 

 

 

 

 

 

 

 

 

 

0

0

0

0

0

0

0

0

0

0

0

0

0

1

0

0

0

0

0

0

0

0

0

0

0

0

2

1

0

0

0

0

0

0

0

0

0

0

0

3

0

0

0

0

0

0

0

0

0

0

0

0

4

3

0

0

0

0

0

0

0

0

0

0

0

5

33

14

0

0

1

0

0

0

0

0

0

0

6

46

55

20

3

3

0

1

0

0

0

0

0

7

15

30

62

61

41

19

9

2

4

0

0

0

8

2

1

17

34

53

67

66

45

41

24

6

3

9

0

0

0

1

3

14

21

41

48

47

24

18

10

0

0

0

0

0

0

3

13

7

28

70

80

 

 

 

 

 

 

 

 

 

 

 

 

 

% control:

100

100

100

100

100

100

100

100

100

100

100

100

Table above, data for the Netherlands (2000-2010), results for autumn & winter (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: U.K.
adult argenteus in October, ringed in the Netherlands. (79042 bytes)Herring Gull AD8.T ad (argenteus), October 27 2010, Westkapelle, the Netherlands.
rings argenteus: France

2cy argenteus in March, ringed in France. (57822 bytes)Herring Gull T2A adult (argenteus, October 01 2008, Boulogne/Mer, France (50.42N,1.34E). Picture: J-M Sauvage.

rings argenteus: Belgium
2cy argenteus in March, ringed in France. (57822 bytes)Herring Gull CZAN 4+cy (argenteus), October 01 2009, Westkapelle, Netherlands.
1cy argenteus in November, ringed in Belgium. (25637 bytes)Herring Gull GCAC adult (argenteus), October 30 2009, Westkapelle, the Netherlands (51.33N-03.25E).
1cy argenteus in November, ringed in Belgium. (25637 bytes)Herring Gull KPAL adult (argenteus), October 23 2009, Boulogne/Mer, France (50.42N,1.34E). Picture: J-M Sauvage.
ad LBBG in winter, ringed in the Netherlands. (65647 bytes)Herring Gull (argenteus) adult PJAT October 31 2012, Boulogne-sur-Mer, NW France. Picture: Jean-Michel Sauvage.
adult argenteus in October, ringed in the Netherlands. (35116 bytes)Herring Gull H-47720 adult (argenteus), October 20 2009, Boulogne/Mer, France (50.42N,1.34E). Picture: J-M Sauvage.
adult argenteus in October, ringed in the Netherlands. (35116 bytes)Herring Gull H-112079 9cy (argenteus), October 04 2008, Boulogne/Mer, France (50.42N,1.34E). Picture: J-M Sauvage.
adult argenteus in October, ringed in the Netherlands. (35116 bytes)Herring Gull H-117482 adult (argenteus), October 28 2008, Boulogne/Mer, France (50.42N,1.34E). Picture: J-M Sauvage.
adult argenteus in October, ringed in Belgium. (60142 bytes)Herring Gull H-119123 adult (argenteus), October 19 2002, Westkapelle, the Netherlands (51.33N-03.25E).
adult argenteus in October, ringed in Belgium. (57563 bytes)Herring Gull H-130477 adult (argenteus), October 11 2003, Westkapelle, the Netherlands (51.33N-03.25E).
No black on P5.
adult argenteus in October, ringed in Belgium. (57563 bytes)Herring Gull argenteus BLB H-161236 July 2010 & October 2014, Le Portel, NW France. Picture: Maarten van Kleinwee & Jean-Michel Sauvage.
rings argenteus: the Netherlands
2cy argentatus in November. (81321 bytes)Herring Gull 0.N adult (argenteus), October 11 2011, Scheveningen, the Netherlands.
adult argenteus in October, ringed in the Netherlands. (79042 bytes)Herring Gull 5W 6cy (argenteus), October 2012, Boulogne/Mer, France (50.42N,1.34E). Picture: J-M Sauvage.
adult argenteus in October, ringed in the Netherlands. (79042 bytes)Herring Gull PY adult (argenteus), October 01 2009, Boulogne/Mer, France (50.42N,1.34E). Picture: J-M Sauvage.
adult argenteus in October, ringed in the Netherlands. (79042 bytes)Herring Gull K5 adult (argenteus), October 06 2009, Westkapelle, the Netherlands (51.33N-03.25E).
adult argenteus in October, ringed in the Netherlands. (79042 bytes)Herring Gull AC adult (argenteus), October 26 2007, Westkapelle, the Netherlands (51.33N-03.25E).
1cy argenteus in August, ringed in Belgium. (90559 bytes)Herring Gull Y.AHY adult (argenteus), October 09 2009, IJmuiden, the Netherlands.
1cy argenteus in August, ringed in Belgium. (90559 bytes)Herring Gull F.ABD adult (argenteus), October 09-15 2012, Katwijk, the Netherlands.
adult argenteus in October, ringed in the Netherlands. (79042 bytes)Herring Gull JR9 10cy (argenteus), October 19 2002, Brouwersdam, the Netherlands  (51.457N-03.51E).
2cy argenteus in March, ringed in France. (57822 bytes)Herring Gull 34 24cy (argenteus, October 09 2011, IJmuiden, Netherlands.
2cy argenteus in March, ringed in France. (57822 bytes)Herring Gull DA 24-27cy (argenteus, 2009-2010, Leiden, Netherlands.
adult argenteus in October, ringed in the Netherlands. (70265 bytes)Herring Gull N adult (argenteus), October 01 2009, Westkapelle, the Netherlands (51.33N-03.25E).
adult argenteus in October, ringed in the Netherlands. (70265 bytes)Herring Gull B adult (argenteus), October 13 2001, Westkapelle, the Netherlands (51.33N-03.25E).
2cy argentatus in November. (81321 bytes)Herring Gull Eadult (argenteus), October 11 2011, Scheveningen, the Netherlands.
adult argenteus in October, ringed in the Netherlands. (35116 bytes)Herring Gull 5.038.584 adult (argenteus), October 01 2009, Westkapelle, the Netherlands (51.33N-03.25E).
adult argenteus in October, ringed in the Netherlands. (35116 bytes)Herring Gull 5.139.994 9cy (argenteus), October 22 2002, IJmuiden, the Netherlands  (52.27N-04.33E).
juvenile LBBG in October, ringed in Norway. (131273 bytes)Herring Gull 5.286.322 adult (argenteus), October 09 2005, Westkapelle, the Netherlands (51.33N-03.25E).
adult argenteus in October, ringed in the Netherlands. (35116 bytes)Herring Gull 5.366.897 adult (argenteus), October 19 2009, Boulogne/Mer, France (50.42N,1.34E). Picture: J-M Sauvage.
adult argenteus in October, ringed in the Netherlands. (35116 bytes)Herring Gull 5.429.309 4+cy (argenteus), October 16 2011, IJmuiden, the Netherlands.
rings argentatus: Germany
adult argentatus in October, ringed in Germany. (75679 bytes)Herring Gull X994 adult (argentatus), October 02 2001 & October 23 2002, Boulogne/Mer, France (50.43N-01.37E).
rings argentatus: Denmark
adult argentatus in October, ringed in Denmark. (132744 bytes)Herring Gull x246862 adult (argentatus), October 21 2004, Westkapelle, the Netherlands (51.33N 03.25E). Picture Pim Wolf.
rings argentatus: Estonia
adult argentatus in October, ringed in Denmark. (132744 bytes)Herring Gull T41614 15cy (argentatus), October 26 2007, Westkapelle, the Netherlands (51.33N 03.25E).
unringed adult Herring Gulls
2cy argenteus in March, ringed in France. (57822 bytes)Herring Gull adult, October 07 2012, Noordwijk, the Netherlands. P7 fully grown, P10 old. PMS=40. Greater primary coverts plain grey indicate full adult.
2cy argenteus in March, ringed in France. (57822 bytes)Herring Gull adult, October 11 2012, Noordwijkerhout, the Netherlands. P7 fully grown. PMS=43. Greater primary coverts plain grey indicate full adult.
2cy argenteus in March, ringed in France. (57822 bytes)Herring Gull (argenteus) adult, October 19 2012, Katwijk, the Netherlands. P10 fully grown. Much black on bill, but plain grey greater primary coverts indicate full adult plumage.
2cy argenteus in March, ringed in France. (57822 bytes)Herring Gull adult, October 11 2012, Noordwijkerhout, the Netherlands. P8 fully grown. PMS=47.
2cy argenteus in March, ringed in France. (57822 bytes)Herring Gull (argenteus) adult, October 19 2012, Katwijk, the Netherlands. P8 fully grown, P9-P10 growing. Plain grey greater primary coverts indicate full adult plumage.
2cy argentatus in November. (81321 bytes)Herring Gull adult (argentatus), October 11 2011, Scheveningen, the Netherlands.
2cy argentatus in November. (81321 bytes)Herring Gull adult (argentatus), October 11 2011, Scheveningen, the Netherlands.
2cy argentatus in November. (81321 bytes)Herring Gull adult (argentatus), October 11 2011, Scheveningen, the Netherlands.
2cy argentatus in November. (81321 bytes)Herring Gull adult (argentatus), October 11 2011, Scheveningen, the Netherlands.
2cy argentatus in November. (81321 bytes)Herring Gull adult (argentatus), October 11 2011, Scheveningen, the Netherlands.
2cy argentatus in November. (81321 bytes)Herring Gull adult (argentatus), October 11 2011, Scheveningen, the Netherlands.
adult argentatus in October. (50783 bytes)Herring Gull adult (argentatus), October 20 2003, IJmuiden, the Netherlands (52.27N - 04.33E).
adult argentatus in October. (43355 bytes)Herring Gull adult (argentatus), October 20 2003, IJmuiden, the Netherlands (52.27N - 04.33E).