Herring Gull- Zilvermeeuw (argentatus & argenteus)
(last update: December 15, 2011
Herring Gull adults September
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 Gull in September
Adults are in active moult. Simultaneously,most birds are in the last phase of the wing-covert moult: the central greater coverts and lesser coverts are replaced.
Tables & Graph
remaining AUTUMN |
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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 |
|
|
|
|
|
|
|
|
|
|
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|
|
|
|
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 |
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|
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|
|
|
|
% class: |
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|
|
|
|
|
|
|
|
|
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 |
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 |
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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 |
|
|
|
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|
|
|
|
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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 |
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% class: |
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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 |
|
|
|
|
|
|
|
|
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% 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.
Herring
Gull EA592432 adult (argenteus), September 16 2009, Boulogne/Mer, France. Picture: J-M Sauvage.
Herring
Gull AJAT 13cy (argenteus), September 20 2011, Westkapelle, Netherlands.
Herring
Gull CAAX 12cy (argenteus), September 21 2011, Westkapelle, Netherlands.
Herring
Gull CTAZ 4+cy (argenteus), September 20-21 2010, Westkapelle, Netherlands.
Herring
Gull CZAN 4+cy (argenteus), September 20 2009, Westkapelle, Netherlands.
Herring
Gull CZAS 4+cy (argenteus), September 2009 & 2011, Westkapelle, Netherlands.
Herring
Gull FCAR 6cy (argenteus), September 11 2011, Boulogne/Mer, France. Picture: J-M Sauvage.
Herring
Gull GAAJ 4+cy (argenteus), September 20 2009, Westkapelle, Netherlands.
Herring
Gull GAAY 4+cy (argenteus), September 20 2011, Westkapelle, Netherlands.
Herring
Gull GCAP 4+cy (argenteus), September 2009 & 2010, Westkapelle, Netherlands.
Herring
Gull KPAV 12cy (argenteus), September 20 2010, Westkapelle, Netherlands.
Herring
Gull H-5094912+cy (argenteus), 2010-2011, Leiden, the Netherlands.
Herring
Gull L-102351 adult (argenteus), September 30 2010, Boulogne/Mer, France (50.42N,1.34E). Picture: J-M Sauvage.
Herring Gull H-127051 adult (argenteus), September 25 2012, Katwijk, the Netherlands.
Herring
Gull H-131099 9cy (argenteus), September 16 2011, Boulogne/Mer, France (50.42N,1.34E). Picture: J-M Sauvage. Also as 6cy.
Herring
Gull H-132415 7cy (argenteus), September 30 2010, Boulogne/Mer, France (50.42N,1.34E). Picture: J-M Sauvage.
Herring
Gull H-136798 adult (argenteus), September 03 2011, IJmuiden, the Netherlands.
Herring Gull H-137233 adult (argenteus), August & September 2012, Katwijk, the Netherlands.
Herring
Gull H-1512x xadult (argenteus), September 22 2011, Westkapelle, the Netherlands.
Herring
Gull H-151443 6+cy (argenteus), September 21 2011, Westkapelle, the Netherlands.
Herring Gull H-153256 adult (argenteus), September 25 & 28 2012, Katwijk, the Netherlands.
Herring
Gull H-152381adult (argenteus), September 20 2011, Westkapelle, the Netherlands.
Herring
Gull L-99798 11-12cy (argenteus), 2011-2012, IJmuiden, the Netherlands.
Herring
Gull H-xxxxxx adult (argenteus), September 05 2009, IJmuiden, the Netherlands. Yellowish legs.
Herring
Gull Y.ACL 6+cy (argenteus), August-September 2010, the Netherlands.
Herring
Gull Y.ACL 4+cy (argenteus), September 05 2010, IJmuiden, the Netherlands.
Herring
Gull DA 24-27cy (argenteus, 2009-2010, Leiden, Netherlands.
Herring
Gull adult (argenteus) SA
September 24 2002 & September 26 2003, IJmuiden, the Netherlands (52.27N
04.33E).
Herring
Gull adult (argenteus) 7--,
September 22 2003, IJmuiden, the Netherlands (52.27N
- 04.33E).
Herring
Gull adult (argenteus) S---,
September 26 2003, IJmuiden, the Netherlands (52.27N
- 04.33E).
Herring
Gull E2 adult (argenteus), September 19 2009, Westkapelle, Netherlands. 
Herring
Gull EN adult (argenteus), September 19 2009, Westkapelle, Netherlands. 
Herring
Gull A4 adult (argenteus), September 20 2009, Westkapelle, Netherlands. 
Herring
Gull AA adult (argenteus), September 19 2009, Westkapelle, Netherlands. 
Herring
Gull AC adult (argenteus), September 19 2009, Westkapelle, Netherlands. 
Herring
Gull H1 adult (argenteus), September 19 2009, Westkapelle, Netherlands.
Herring
Gull JA adult (argenteus), September 24 2010, Westkapelle, Netherlands.
Herring
Gull JZ adult (argenteus), September 19 2009, Westkapelle, Netherlands.
Herring
Gull K9 adult (argenteus), September 19 2009, Westkapelle, Netherlands.
Herring
Gull MK adult (argenteus), September 24 2010, Westkapelle, Netherlands.
Herring
Gull PJ adult (argenteus), September 22 2010, Westkapelle, Netherlands.
Herring
Gull RJ adult (argenteus), September 2009 & 2010, Westkapelle, Netherlands.
Herring
Gull S7 adult (argenteus), September 20 2011, Westkapelle, Netherlands.
Herring
Gull SD adult (argenteus), September 20 2011, Westkapelle, Netherlands.
Herring
Gull 3V adult (argenteus), September 22 2010, Westkapelle, Netherlands. 
Herring
Gull 49 adult (argenteus), September 21 2009, Westkapelle, Netherlands. 
Herring
Gull 65 adult (argenteus), September 24 2009, Westkapelle, the Netherlands.
Herring
Gull Y.AFL adult (argenteus), March 2010 & September 2011, IJmuiden, the Netherlands.
Herring
Gull Y.AFM adult (argenteus), September 23 2010, IJmuiden, the Netherlands.
Herring
Gull Y.ASD adult (argenteus), September 23 2010, IJmuiden, the Netherlands.
Herring
Gull M.ABB adult (argenteus), August-September 2011, Leiden, the Netherlands.
Herring
Gull M.ABK adult (argenteus), September 21 2010, Westkapelle, the Netherlands.
Herring
Gull E096 adult (argenteus), September 05 2010, IJmuiden, Netherlands. Picture: M v Kleinwee.
Herring
Gull NLA.5.425.481 4+cy (argenteus), September 2011 - January 2012, IJmuiden, the Netherlands.
Herring
Gull 11cy (argenteus) 5.293.863
September 21 2004, Scheveningen, the Netherlands.
Herring
Gull 11cy 5.352.700 (argenteus), September 23 2011, Scheveningen, the Netherlands.
Herring
Gull adult (argenteus) 5.360.695 September
18 2004, IJmuiden, the Netherlands (52.27N 04.33E).
Herring
Gull 10+cy (argenteus) 5.362.516 September 01 2006, IJmuiden, the Netherlands (52.27N 04.33E).
Herring
Gull 9+cy (argenteus) 5.369.341 September 19 2008, IJmuiden, the Netherlands (52.27N 04.33E).
Herring Gull 6.126.721 5cy (argenteus), September 03 2011, IJmuiden, the Netherlands.
Herring
Gull adult (argenteus) 5.157.xxx,
September 24 2002, Scheveningen, the Netherlands. A bird with
yellowish legs.
Herring
Gull adult (argenteus) 5.360.???,
September 24 2002, IJmuiden, the Netherlands (52.27N
04.33E).
Herring
Gull AB97 9cy (argentatus), September 25 2009, Barneveld, the Netherlands.
Herring
Gull adult, September 12 2012, IJmuiden, the Netherlands.
Herring
Gull adult, September 12 2012, IJmuiden, the Netherlands.
Herring
Gull adult, September 12 2012, IJmuiden, the Netherlands.