Herring Gull - L. argentatus

Herring Gull- Zilvermeeuw (argentatus & argenteus)

(last update: December 15, 2011 )

Coordinators:
Jean-Michel Sauvage (France)
Mars Muusse (the Netherlands)

Herring Gull plumages:

hg 1cy July
hg 1cy August
hg 1cy September
hg 1cy October
hg 1cy November
hg 1cy December

hg 2cy January
hg 2cy February
hg 2cy March
hg 2cy April
hg 2cy May
hg 2cy June
hg 2cy July
hg 2cy August
hg 2cy September
hg 2cy October
hg 2cy November
hg 2cy December

hg 3cy January
hg 3cy February
hg 3cy March
hg 3cy April
hg 3cy May
hg 3cy June
hg 3cy July
hg 3cy August
hg 3cy September
hg 3cy October
hg 3cy November
hg 3cy December

hg sub-ad January
hg sub-ad February
hg sub-ad March
hg sub-ad April
hg sub-ad May
hg sub-ad June
hg sub-ad July
hg sub-ad August
hg sub-ad September
hg sub-ad October
hg sub-ad November
hg sub-ad December

hg ad January
hg ad February
hg ad March
hg ad April
hg ad May
hg ad June
hg ad July
hg ad August
hg ad September
hg ad October
hg ad November
hg ad December

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

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).

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.

Herring Gull H-112079 9cy (argenteus), October 04 2008, Boulogne/Mer, France (50.42N,1.34E). Picture: J-M Sauvage.

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.

rings argenteus: the Netherlands

Herring Gull 0.N adult (argenteus), October 11 2011, Scheveningen, the Netherlands.

Herring Gull 5W 6cy (argenteus), October 2012, Boulogne/Mer, France (50.42N,1.34E). Picture: J-M Sauvage.

Herring Gull PY adult (argenteus), October 01 2009, Boulogne/Mer, France (50.42N,1.34E). Picture: J-M Sauvage.

Herring Gull K5 adult (argenteus), October 06 2009, Westkapelle, the Netherlands (51.33N-03.25E).

Herring Gull AC adult (argenteus), October 26 2007, Westkapelle, the Netherlands (51.33N-03.25E).

Herring Gull Y.AHY adult (argenteus), October 09 2009, IJmuiden, the Netherlands.

Herring Gull F.ABD adult (argenteus), October 09-15 2012, Katwijk, the Netherlands.

Herring Gull JR9 10cy (argenteus), October 19 2002, Brouwersdam, the Netherlands (51.457N-03.51E).

Herring Gull 34 24cy (argenteus, October 09 2011, IJmuiden, Netherlands.

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).

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.

Herring Gull 5.038.584 adult (argenteus), October 01 2009, Westkapelle, the Netherlands (51.33N-03.25E).

Herring Gull 5.139.994 9cy (argenteus), October 22 2002, IJmuiden, the Netherlands (52.27N-04.33E).

Herring Gull 5.286.322 adult (argenteus), October 09 2005, Westkapelle, the Netherlands (51.33N-03.25E).

Herring Gull 5.366.897 adult (argenteus), October 19 2009, Boulogne/Mer, France (50.42N,1.34E). Picture: J-M Sauvage.

Herring Gull 5.429.309 4+cy (argenteus), October 16 2011, IJmuiden, the Netherlands.

rings argentatus: Germany

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

Herring Gull T41614 15cy (argentatus), October 26 2007, Westkapelle, the Netherlands (51.33N 03.25E).

unringed adult Herring Gulls

Herring Gull adult, October 07 2012, Noordwijk, the Netherlands. P7 fully grown, P10 old. PMS=40. Greater primary coverts plain grey indicate full adult.

Herring Gull adult, October 11 2012, Noordwijkerhout, the Netherlands. P7 fully grown. PMS=43. Greater primary coverts plain grey indicate full adult.

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.

Herring Gull adult, October 11 2012, Noordwijkerhout, the Netherlands. P8 fully grown. PMS=47.

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.

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).