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)

Great Black-backed Gull (Larus marinus) adult, December 05 2008, Brouwersdam, The Netherlands. Picture: Jeroen Bes.

Could be taken for sub-adult, as the bill is very dull coloured. However, the complete moult in this bird is very delayed and the new upper tertials and inner greater coverts show transversal 'growing lines', indicating this may be a weak bird.