Lesser Black-backed Gull (graellsii & intermedius)

(last update: June 26, 2017)

sub-adult: August

Regarding moult pace and strategy, sub-adults don't differ much from full adults. Sometimes it's hard to age sub-adults correct, but on average, some or all of the following features can be found in 4cy:

• relatively pale bare part coloration compared to full adults,
• black markings on the old rectrices, often isolated limited black spots near the centre,
• p10 with a small mirror, p9 lacking such a mirror and very small white tips on the top of the outer primaries. By August, these tips are worn away and the primaries are brownish, strongly bleached,
• the grey centres of the old secondaries show a brown hue and the tips are abraded,
• tertials, outer greater coverts or outer lesser coverts (in the carpal edge) show old adult-like feathers with a relative strong brown hue, obvious much stronger than expected in full adult coverts.

Used as a single characteristic, the evidence is not very convincing, but individuals that combine these characteristics are probably 4cy or 5cy birds.

sub-adult LBBG: intermedius