Great Black-backed Gull (Larus marinus)(last update: July 12, 2015) |
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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. |