Great Black-backed Gull (Larus marinus)

(last update: July 12, 2015)

Great Black-backed Gull (Larus marinus) sub-adult: March 20 2004, IJmuiden, the Netherlands (52.27 N, 04.33 E).

In many respects this bird resembles a full adult, with very limited barred coverts (but note the pattern of the central lesser coverts), and with an obvious bill-band. Note the complete white tail and very large white tips of the outer primaries and an obvious white mirror on the outermost primary P10. This is probably a 5cy bird.