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 (Larus marinus) 4CY, July 30 2014, IJmuiden, the Netherlands.

Immature bird in complete moult: P7-P10 old, old P10 with large mirror (indication for 4CY age). Old 3rd gen secondaries with brownish centres and vermiculated along edges. Active moult in other feather tracts as well, prominent in coverts which are replaced for fresh dark feathers.