Gull Research Organisation

Great Black-backed Gull (Larus marinus)

(last update: October 12, 2011)

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

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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.

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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.

Great Black-backed Gull (Larus marinus) 2cy 48C May 14 2008, Boulogne / Mer, France. Picture Jean Michel Sauvage.

Great Black-backed Gull (Larus marinus) 2cy 58J May 10 2012, Boulogne / Mer, France. Picture Jean Michel Sauvage.

Great Black-backed Gull JP241 (Larus marinus) 2cy: May 30 2012, Boulogne / Mer, France. Picture Jean Michel Sauvage.

Great Black-backed Gull JW209 (Larus marinus) 2cy: May 15 2011, Boulogne/Mer, France. Picture: J-M Sauvage.

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.