Great Black-backed Gull (Larus marinus)

(last update: July 12, 2015)

Coordinators:
Jean-Michel Sauvage (France)
Morten Helberg (Norway)
Nils Helge Lorentzen (Norway)
Mars Muusse (Netherlands)

Great Black-backed Gull 2cy May

By April, all the primaries are still juvenile or just P1 dropped in most 2cy GBBG checked at Boulogne-sur-Mer (2000-2004). But from May onwards, primary moult progresses rapidly and in May and June, 2cy Great Black-backed Gull can be the most advanced moulting large gull on continental NW Europe (at least NW France - the Netherlands). Moult progress is even further than Yellow-legged Gulls present at Etaples (near Boulogne-sur-Mer), birds which probably originate from S France and central Europe (ring readings from French Med coast, Italy and Switzerland). This is all based only on small sample sizes, so more resaerch would be appreciated; so far data also indicate that 3cy GBBG are early moulting birds.

A small survey on 2cy GBBG's at Le Portel / Boulogne-sur-Mer in NW France nicely shows the advanced moult in the primaries:

Tables:

Primary moult score of 2cy GBBG L. marinus.
May 16 2002 - Boulogne/Mer, NW France (50.43N,01.37E).

Bert-Jan Luijendijk & Mars Muusse.
REM 9 (p1 missing) 0
REM 8 (p2 missing) 2
REM 7 (p3 missing) 6
REM 6 (p4 missing) 4
REM 5 (p5 missing) 4
REM 6 (p6 missing) 2
n (sample size): 18
m (average): 6,1
SD (stand dev): 1,23
Notes:
m (average) = number of remaining old juvenile primaries.

.

Primary moult score of 2cy YLG L. michahellis.
May 2001 / 2002 - Etaples, NW France (50.30N,01.37E).

Bert-Jan Luijendijk & Mars Muusse.
date: May 06 2001 May 16 2002
REM 10 (no missing) 1 0
REM 9 (p1 missing) 2 0
REM 8 (p2 missing) 4 4
REM 7 (p3 missing) 6 19
REM 6 (p4 missing) 4 16
REM 5 (p5 missing) 0 4
n (sample size): 17 43
m (average): 7,4 6,5
SD (stand dev): 1,18 0,80
Notes:
m (average) = number of remaining old juvenile primaries.
Michahellis 2cy unringed birds have been scored on many feather tracts in spring at Etaples, NW France. For tables and charts see YLG 2cy MAY.

.

Primary moult score of 2cy HG L. argentatus.
May 17 2002 - Boulogne/Mer, NW France (50.43N,01.37E).

Bert-Jan Luijendijk & Mars Muusse.
REM 9 (p1 missing) 2
REM 8 (p2 missing) 8
REM 7 (p3 missing) 36
REM 6 (p4 missing) 27
REM 5 (p5 missing) 2
REM 6 (p6 missing) 0
n (sample size): 75
m (average): 6,75
SD (stand dev): 0,79
Notes:
m (average) = number of remaining old juvenile primaries.
Argentatus / argenteus 2cy unringed birds have been scored on PMS many times in spring at Scheveningen, the Netherlands. For tables and charts see HG 2cy MAY.

.

remaining 
1
2
3
4
5
6
7
7
8
8
9
10
11
12
remain/new P       
rem
rem
rem
rem
rem
rem
rem
new
rem
new
new
new
new
n(tot) 213
jan
feb
mrch
apr
may
june
july
july
aug
aug
sept
oct
nov
dec
0
.
.
.
.
.
.
1
.
11
.
.
.
.
.
1
.
.
.
.
.
.
.
.
8
.
.
.
.
.
2
.
.
.
.
.
1
3
.
3
.
.
.
.
.
3
.
.
.
.
.
8
4
.
.
.
.
.
.
.
4
.
.
.
.
2
10
.
.
.
.
.
.
.
.
5
.
.
.
.
4
.
.
5
.
.
.
.
.
.
6
.
.
.
1
4
.
.
2
.
6
.
.
.
.
7
.
.
.
.
6
.
.
.
.
13
3
.
.
.
8
.
.
.
.
2
.
.
1
.
2
4
2
1
.
9
.
.
.
2
.
.
.
.
.
.
14
5
4
.
10
31
32
24
5
.
.
.
.
.
.
.
6
6
7
n=
31
32
24
8
18
19
8
8
22
21
21
13
11
7
average m:
10,0
10,0
10,0
9,3
6,1
3,5
2,3
5,6
0,6
6,8
8,5
9,3
9,5
10,0
95% CID
0,00
0,00
0,00
1,16
0,61
0,29
0,87
0,89
0,32
0,27
0,34
0,45
0,46
0,00
inverse 
2,04
2,04
2,07
2,36
2,11
2,10
2,36
2,36
2,08
2,09
2,09
2,18
2,23
2,45
Variance (s2)
0,00
0,00
0,00
1,93
1,52
0,37
1,07
1,13
0,53
0,36
0,56
0,56
0,47
0,00
SD (s)
0,00
0,00
0,00
1,39
1,23
0,61
1,04
1,06
0,73
0,60
0,75
0,75
0,69
0,00
SE (sx) 
0,00
0,00
0,00
0,49
0,29
0,14
0,37
0,38
0,15
0,13
0,16
0,21
0,21
0,00
Percentage
0
0
0
0
0
0
0
13
0
50
0
0
0
0
0
1
0
0
0
0
0
0
0
0
36
0
0
0
0
0
2
0
0
0
0
0
5
38
0
14
0
0
0
0
0
3
0
0
0
0
0
42
50
0
0
0
0
0
0
0
4
0
0
0
0
11
53
0
0
0
0
0
0
0
0
5
0
0
0
0
22
0
0
63
0
0
0
0
0
0
6
0
0
0
13
22
0
0
25
0
29
0
0
0
0
7
0
0
0
0
33
0
0
0
0
62
14
0
0
0
8
0
0
0
0
11
0
0
13
0
10
19
15
9
0
9
0
0
0
25
0
0
0
0
0
0
67
38
36
0
10
100
100
100
63
0
0
0
0
0
0
0
46
55
100
% Controll
100
100
100
100
100
100
100
100
100
100
100
100
100
100

Notes:
Sample of only ringed birds for: Jan, Febr, Mrch, July, Aug, Sept, Oct, Nov, Dec.
Sample of unringed birds for May & June
Sample of mixed ringed and unringed birds for April.

7095jp36.jpg (66909 bytes)Great Black-backed Gull (Larus marinus) 48C 2cy, May 14 2008, Boulogne / Mer, France. Picture Jean Michel Sauvage.
7095jp36.jpg (66909 bytes)Great Black-backed Gull (Larus marinus) 58J 2CY, May 10 2012, Boulogne / Mer, France. Picture Jean Michel Sauvage.
1598.jpg (74227 bytes)GreatBlack-backed Gull (Larus marinus) JJ670 2cy, May 29 2017, Heemskerk, the Netherlands.
gbbg Great Black-backed Gull (Larus marinus) JP2412cy, May 30 2012, Boulogne / Mer, France. Picture Jean Michel Sauvage.
1598.jpg (74227 bytes)Great Black-backed Gull (Larus marinus) JW209 2cy, May 15 2011, Boulogne/Mer, France. Picture: J-M Sauvage.
1598.jpg (74227 bytes)Great Black-backed Gull (Larus marinus) JWR44 2cy, May 29 2017, Heemskerk, the Netherlands.
1598.jpg (74227 bytes)Great Black-backed Gull (Larus marinus) JWX63 2cy, May 29 2017, Heemskerk, the Netherlands.
2121gbbgad.jpg (50050 bytes)Great Black-backed Gull (Larus marinus) 3U4 September 2013 & May 2014, New York & Whiting. Picture: Brad Carlson & Amar Ayyash.
7095jp36.jpg (66909 bytes)Great Black-backed Gull (Larus marinus) 1VS 2CY, May 15 2014, Howth, Ireland. Picture: Graham Prole.
7095jp36.jpg (66909 bytes)Great Black-backed Gull (Larus marinus) 3CL 2CY, April - May 2014, Howth, Dublin, Ireland. Picture: Graham Prole.
8471j52c.jpg (85052 bytes)Great Black-backed Gull (Larus marinus) DKC 3M-3206 2cy, March - May 2015, IJmuiden, the Netherlands.
8471j52c.jpg (85052 bytes)Great Black-backed Gull (Larus marinus) 2CY, May 09 2017, Katwijk, the Netherlands.
8471j52c.jpg (85052 bytes)Great Black-backed Gull (Larus marinus) 2CY, May 27 2015, IJmuiden, the Netherlands.
8471j52c.jpg (85052 bytes)Great Black-backed Gull (Larus marinus) 2CY, May 27 2015, IJmuiden, the Netherlands.
8471j52c.jpg (85052 bytes)Great Black-backed Gull (Larus marinus) 2CY, May 27 2015, IJmuiden, the Netherlands.
8471j52c.jpg (85052 bytes)Great Black-backed Gull (Larus marinus) 2CY, May 27 2015, IJmuiden, the Netherlands.
8471j52c.jpg (85052 bytes)Great Black-backed Gull (Larus marinus) 2CY, May 27 2015, IJmuiden, the Netherlands.
8471j52c.jpg (85052 bytes)Great Black-backed Gull (Larus marinus) 2CY, May 27 2015, IJmuiden, the Netherlands.
8471j52c.jpg (85052 bytes)Great Black-backed Gull (Larus marinus) 2CY, May 27 2015, IJmuiden, the Netherlands.
8471j52c.jpg (85052 bytes)Great Black-backed Gull (Larus marinus) 2CY, May 27 2015, IJmuiden, the Netherlands.
8471j52c.jpg (85052 bytes)Great Black-backed Gull (Larus marinus) 2CY, May 27 2015, IJmuiden, the Netherlands.
gbbg400.jpg (61674 bytes)Great Black-backed Gull (Larus marinus) 2cy: May 16 2002, Le Portel - Boulogne sur Mer, France (50.42 N - 01.34 E). Two images. Primaries p1 and p2 have been replaced.
gbbg2cy578.jpg (74447 bytes)Great Black-backed Gull (Larus marinus) 2cy: May 17 2002, Le Portel - Boulogne sur Mer, France (50.42 N - 01.34 E). Two images. Primaries p4 is still juvenile.
gbbg539.jpg (66818 bytes)Great Black-backed Gull (Larus marinus) 2cy: May 17 2002, Le Portel - Boulogne sur Mer, France (50.42 N - 01.34 E). Primaries p4 is still juvenile and the median coverts are growing inwards from then outer wing.
gbbg572.jpg (67350 bytes)Great Black-backed Gull (Larus marinus) 2cy: May 17 2002, Le Portel - Boulogne sur Mer, France (50.42 N - 01.34 E). This bird shows the difference between freshly moulted greater and median coverts (those are warm brown based) and the earlier acquired second generation central greater coverts.
gbbg582.jpg (71459 bytes)Great Black-backed Gull (Larus marinus) 2cy: May 17 2002, Le Portel - Boulogne sur Mer, France (50.42 N - 01.34 E). Note the characteristic pattern of the fresh lower scapulars.
gbbg588.jpg (81350 bytes)Great Black-backed Gull (Larus marinus) 2cy: May 17 2002, Le Portel - Boulogne sur Mer, France (50.42 N - 01.34 E). The complete row of median coverts has been renewed. P6 is missing and the rctrices are actively moulted.
gbbg599.jpg (69086 bytes)Great Black-backed Gull (Larus marinus) 2cy: May 17 2002, Le Portel - Boulogne sur Mer, France (50.42 N - 01.34 E). An individual with active moult in the rectrices, as a very loose tail-feather indicates. Primary moult has only arrived at p3, which is missing.
gbbg568.jpg (67873 bytes)Great Black-backed Gull (Larus marinus) 2cy: May 17 2002, Le Portel - Boulogne sur Mer, France (50.42 N - 01.34 E). Two images. An individual with thin patterns on the old second generation scapulars.
gbbg559.jpg (62151 bytes)Great Black-backed Gull (Larus marinus) 2cy: May 17 2002, Le Portel - Boulogne sur Mer, France (50.42 N - 01.34 E). Note the almost white lower scapulars.
gbbg570.jpg (69268 bytes)Great Black-backed Gull (Larus marinus) 2cy: May 17 2002, Le Portel - Boulogne sur Mer, France (50.42 N - 01.34 E). An advanced individual regarding the wing-covert moult.