Lesser Black-backed Gull with features suggesting immatures.

Ageing of immature LBBG can be difficult in some birds, due to individual variation.

Plus: features which apply to immature birds in other taxa (e.g. Herring Gull Larus argentatus), can not safely be used in all LBBG.

Here, we list some ringed LBBG, which may resemble sub-adults, as they show "immature characteristics".

1) 3cy LBBG can be aged by P10 without a mirror.

Not always true. We have seen several ringed LBBG, older than 3cy and up to 5cy, still lacking a mirror on P10.

Examples are E347 red; L-89472 Metal; 5.364.457 Metal; 32 orange; HZ orange. Most of these birds have the primaries raher neat dark brown to black, where 3cy birds may show more abraded outer primaries. However, 5cy 5.364.457 Metal illustrates that older birds can show worn primaries too.

2) 3cy LBBG can be aged by a broad black band on the bill.

Not always true. We have seen several ringed LBBG, older than 3cy and up to 12cy, showing such dark markings on the bill. Such birds show black on the bill even throughout the breeding season. In the breeding season, thinner black bill-bands have been recorded even on a 14cy female as well, breeding at Maasvlakte Holland.

3) immature LBBG can be aged by dark greater primary coverts.

Not always true. We have seen several ringed LBBG, older than 5cy, showing extensive black on the primary coverts.
A large set of ringed (proven age) birds can be found HERE.

Solution: when describing the variation of LBBG, only include ringed individuals of certain age.