Herring Gull- Zilvermeeuw (argentatus & argenteus)

(last update: December 15, 2014 )

Herring Gull adults December


Noordwijk, December 15 2014 when tons of starfishes and ensis beached after storm. 15.000+ gulls present.

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".


Noordwijk, December 15 2014 when tons of starfishes and ensis beached after storm. 15.000+ gulls present.

Tables & Graph

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.  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 in the Adult January Section.

Adult argenteus from the Netherlands and Belgium have finished the complete moult, bur argentatus from Scandinavia may still show active moult in the outer primaries. The table below present the primary moult stage during December.

Primary Moult Score of adult Herring Gull (argenteus & argentatus) at Scheveningen, the Netherlands in December, ranked by date.

date > 02-12-00 07-12-00
P8 - 2
P9 16 13
P10 66 59
n (tot): 82 74
m (av): 9,80 9,77
95% CID: 0,09 0,11
SD (s): 0,40 0,48

n (tot): Total of individuals by date. Total this month, n: 156.
m (av): Average primary moult score by date.
95% CID: 95% Confidence Interval of the Difference.
SD (s): Standard deviation.

Note 1: by December, adults are selected by the plain grey greater primary coverts, large tips on the new primaries and the lack of immature features (thus limited black on the bill and no obvious pigmentation in the iris).

Note 2: in the summer period, the population Herring Gulls in the harbour of Scheveningen consist of local argenteus. From October onwards, figures are strongly influenced by increasing numbers of Scandinavian argentatus.


Noordwijk, December 15 2014 when tons of starfishes and ensis beached after storm. 15.000+ gulls present.

Long term analysis for primary moult score (PMS).

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.

....


Noordwijk, December 15 2014 when tons of starfishes and ensis beached after storm. 15.000+ gulls present.

rings argenteus: Belgium
2cy argenteus in March, ringed in France. (57822 bytes)Herring Gull (argenteus) 14+CY BLB H-122097December 26 2012, Boulogne-sur-Mer, NW France. Picture: Jean-Michel Sauvage.
2cy argenteus in March, ringed in France. (57822 bytes)Herring Gull H128286 10cy (argenteus), December 03 2011, Leiden, Netherlands.
2cy argenteus in March, ringed in France. (57822 bytes)Herring Gull H132951 adult (argenteus), December 13 2012, Boulogne/Mer, France. Picture: J-M Sauvage.
rings argenteus: the Netherlands
1cy argenteus in August, ringed in Belgium. (90559 bytes)Herring Gull Y.AFM adult (argenteus), December 09 2010, IJmuiden, the Netherlands.
1cy argenteus in August, ringed in Belgium. (90559 bytes)Herring Gull Y.AKS adult argenteus), 2009 - 2010, IJmuiden, the Netherlands.
1cy argenteus in August, ringed in Belgium. (90559 bytes)Herring Gull Y.ASD adult (argenteus), December 09 2010, IJmuiden, the Netherlands.
1cy argenteus in August, ringed in Belgium. (90559 bytes)Herring Gull M.ABW adult (argenteus), December 2009 & July 2010, the Netherlands.
1cy argenteus in August, ringed in Belgium. (90559 bytes)Herring Gull F.AAN adult (argenteus), December 07 2010, Katwijk, the Netherlands.
2cy argenteus in March, ringed in France. (57822 bytes)Herring Gull DA 24-27cy (argenteus, 2009-2010, Leiden, Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull (argenteus) adult ZDDecember 02 2013, Katwijk aan Zee, the Netherlands.
2cy argenteus in March, ringed in France. (57822 bytes)Herring Gull NLA.5.277.807 21cy (argenteus), December 03 2012, Boulogne/Mer, France. Picture: J-M Sauvage.
1cy argenteus in August, ringed in Belgium. (90559 bytes)Herring Gull NLA.5.352.764 adult (argenteus), December 23 2010, IJmuiden, the Netherlands.
2cy argenteus in March, ringed in France. (57822 bytes)Herring Gull 5.414.557 6cy (argenteus), December 18 2010, Leiden, Netherlands.
1cy argenteus in August, ringed in Belgium. (90559 bytes)Herring Gull NLA.5.420.527 adult (argenteus), December 31 2008, IJmuiden, the Netherlands.
1cy argenteus in August, ringed in Belgium. (90559 bytes)Herring Gull NLA.5.424.838 adult (argenteus), December 23 2010, IJmuiden, the Netherlands.
rings argentatus: Finland
1cy argenteus in November, ringed in Belgium. (25637 bytes)Herring Gull SFH HT082209 25cy (argentatus), November 2003 & December 2008, Westkapelle, the Netherlands (51.33N - 03.25E). Picture Pim Wolf.
rings argentatus: Russia
1cy argenteus in November, ringed in Belgium. (25637 bytes)Herring Gull (argentatus) KV48 1CY-8CY, 2006-2013, Oostende (Belgium) & Boulogne/Mer (NW France).
 
unringed adult Herring Gulls: with black on P5
3cy argentatus in January. (80207 bytes)Herring Gull adult, December 02 2012, Katwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, December 02 2012, Katwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult (argentatus), December 02 2012, Katwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult (argentatus), December 02 2012, Katwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult (argentatus), December 19 2011, Noordwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, December 02 2012, Katwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, December 02 2012, Katwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, December 02 2012, Katwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, December 02 2012, Katwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, December 03 2013, Katwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, December 03 2013, Katwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, December 03 2013, Katwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, December 02 2012, Katwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, December 02 2012, Katwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, December 15 2014, Noordwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, December 15 2014, Noordwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, December 15 2014, Noordwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, December 15 2014, Noordwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, December 15 2014, Noordwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, December 15 2014, Noordwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, December 15 2014, Noordwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, December 15 2014, Noordwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, December 15 2014, Noordwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, December 15 2014, Noordwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, December 15 2014, Noordwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, December 15 2014, Noordwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, December 15 2014, Noordwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, December 15 2014, Noordwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, December 15 2014, Noordwijk, the Netherlands.
unringed adult Herring Gulls:
thayeri
patterns or no black on P5

3cy argentatus in January. (80207 bytes)Herring Gull argentatus adult, December 06 2013, Noordwijk, the Netherlands. Thayeri on P9-P10, no black on P5.
3cy argentatus in January. (80207 bytes)Herring Gull adult (argentatus), December 02 2012, Katwijk, the Netherlands. Thayeri on P9.
3cy argentatus in January. (80207 bytes)Herring Gull adult, December 15 2014, Noordwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult (argentatus), December 02 2012, Katwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult (argentatus), December 08 2009, Scheveningen, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult (argentatus), December 19 2011, Noordwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult (argentatus), December 19 2011, Noordwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, December 02 2012, Katwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, December 03 2013, Katwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, December 15 2014, Noordwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult (argentatus), December 02 2012, Katwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, December 15 2014, Noordwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, December 15 2014, Noordwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, December 15 2014, Noordwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, December 15 2014, Noordwijk, the Netherlands.
unringed adult Herring Gulls:
with black on P4

3cy argentatus in January. (80207 bytes)Herring Gull adult, December 02 2012, Katwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, December 15 2014, Noordwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, December 15 2014, Noordwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, December 15 2014, Noordwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, December 15 2014, Noordwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, December 03 2013, Katwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, December 03 2013, Katwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, December 02 2012, Katwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, December 15 2014, Noordwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, December 03 2013, Katwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, December 03 2013, Katwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, December 03 2013, Katwijk, the Netherlands.
3cy argentatus in January. (80207 bytes)Herring Gull adult, December 03 2013, Katwijk, the Netherlands.