Great Black-backed Gull (Larus marinus)

(last update: July 12, 2015)

Great Black-backed Gull (Larus marinus) sub-adult, July 11 2002, Le Portel - Boulogne sur Mer, France (50.42 N - 01.34 E).

Ageing GBBG may be difficult in sub-adult plumages, but some clues can be found in this bird. The greater coverts are clearly more abraded than the adjacent median coverts, except greater covert #5 which was moulted last in line. The outer lesser coverts show brown-hued centres and the white tips of the tertials are worn away. On average, the upper-parts appear very messy and the older wing-coverts appear weaker than can be expected in full adult plumage.