Great Black-backed Gull (Larus marinus)

(last update: July 12, 2015)

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

Great Black-backed Gull (Larus marinus) sub-adult, July 30 2014, IJmuiden, the Netherlands.

Immature bird (3CY-4CY) in complete moult: P8-P10 old. PMS=26. Active moult in other feather tracts as well, prominent in coverts which are replaced for blackish fresh feathers. Old P10 with small mirror; secondaries with brownish centres and vermiculated along edges.