Great Black-backed Gull (Larus marinus)
(last update: July 12, 2015)
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: |
||||||||||||||
Great
Black-backed Gull (Larus marinus) 48C 2cy, May 14 2008, Boulogne / Mer, France. Picture Jean Michel Sauvage.
Great
Black-backed Gull (Larus marinus) 58J 2CY, May 10 2012, Boulogne / Mer, France. Picture Jean Michel Sauvage.
GreatBlack-backed Gull (Larus marinus) JJ670 2cy, May 29 2017, Heemskerk, the Netherlands.
Great
Black-backed Gull (Larus marinus) JP2412cy, May 30 2012, Boulogne / Mer, France. Picture Jean Michel Sauvage.
Great
Black-backed Gull (Larus marinus) JW209 2cy, May 15 2011, Boulogne/Mer, France. Picture: J-M Sauvage. 
Great Black-backed Gull (Larus marinus) JWR44 2cy, May 29 2017, Heemskerk, the Netherlands.
Great Black-backed Gull (Larus marinus) JWX63 2cy, May 29 2017, Heemskerk, the Netherlands.
Great Black-backed Gull (Larus marinus) 3U4 September 2013 & May 2014, New York & Whiting. Picture: Brad Carlson & Amar Ayyash.
Great Black-backed Gull (Larus marinus) 1VS 2CY, May 15 2014, Howth, Ireland. Picture: Graham Prole.
Great Black-backed Gull (Larus marinus) 3CL 2CY, April - May 2014, Howth, Dublin, Ireland. Picture: Graham Prole.
Great Black-backed Gull (Larus marinus) DKC 3M-3206 2cy, March - May 2015, IJmuiden, the Netherlands.
Great Black-backed Gull (Larus marinus) 2CY, May 09 2017, Katwijk, the Netherlands.
Great Black-backed Gull (Larus marinus) 2CY, May 27 2015, IJmuiden, the Netherlands.
Great Black-backed Gull (Larus marinus) 2CY, May 27 2015, IJmuiden, the Netherlands.
Great Black-backed Gull (Larus marinus) 2CY, May 27 2015, IJmuiden, the Netherlands.
Great Black-backed Gull (Larus marinus) 2CY, May 27 2015, IJmuiden, the Netherlands.
Great Black-backed Gull (Larus marinus) 2CY, May 27 2015, IJmuiden, the Netherlands.
Great Black-backed Gull (Larus marinus) 2CY, May 27 2015, IJmuiden, the Netherlands.
Great Black-backed Gull (Larus marinus) 2CY, May 27 2015, IJmuiden, the Netherlands.
Great Black-backed Gull (Larus marinus) 2CY, May 27 2015, IJmuiden, the Netherlands.
Great Black-backed Gull (Larus marinus) 2CY, May 27 2015, IJmuiden, the Netherlands.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.