Lesser Black-backed Gull- Kleine Mantelmeeuw (graellsii & intermedius)

(last update: June 25, 2012)

sub-adult: July

In moult pace and moult strategy, sub-adults (4 / 5 cy) strongly resemble adults. Since many sub-adults are pretty hard to separate from adults, it's difficult to be certain about the average plumage in July, because advanced individuals may be aged wrong and subsequently missing in surveys (or are at least underestimated). This seems particularly the case in fast moulting intermedius LBBG, where even full-adults may show very small mirrors on p10 and p9 and the tips of the outer primaries appear relatively small. This makes correct ageing very difficult.

Nevertheless, we feel some characteristics, particularly accumulated in a single individual may point to sub-adultness:

• very small white tips on the old outer primaries (beware wear),
• a very limited white mirror on the old p10 and absence of a mirror on p9,
• isolated black markings on old, worn rectrices,
• brown centred coverts, often found in the carpal edge (outer lesser coverts),
• vermiculation on (central) tertials or an accentuated black centre in the tertials, which may have the white tips confined to the inner web,
• immature colouration of bare parts,
• secondaries show brownish centres with a zigzag pattern along the trailing edge.

Used as a single characteristic, the evidence is not very convincing, but individuals that combine these characteristics are probably 4cy or 5cy LBBG. For exctensive research of birds in the hand, see SUB-AD MAY SECTION.