Yellow-legged Gull - Larus michahellis

(last update: October 08 2013)

Delfín González
Gabriel Martín
Antonio Gutierrez
Amir Ben Dov
Mars Muusse

Yellow-legged Gull michahellis 3CY, August 09 2003, Etaples, France (50.42N, 1.34E).

An example of an immature patterned bird, showing many dark centres in the wing-coverts and quite immature bare parts coloration. In this respect, it much resembles 2CY birds.

Primary moult score of 3CY michahellis Yellow-legged Gull, at Etaples, NW France (50.43N, 01.37E) on August 11 2003.
. P5 fg P6 fg P7 fg P8 fg n:
P8-P10 5 - - - 5
P9-P10 3 24 - - 27
P10 old - 10 6 - 16
no old P - - 2 - 2
n: 8 34 8 - 50
n = 50; m new P = 6.0; SD new P = 0.57; m old P = 1.7; SD old P = 0.70.

In 3CY birds, the old second generation flight-feathers are replaced by new, more adult-like third generation feathers. This is most obvious in the (outer) primaries. The old second generation P10 is brown, abraded and will be replaced by glossy-black fresh third generation P10 showing an obvious mirror. The primary moult stage in this bird: P10 is old second generation and P6 is full-grown. P7 is at the length of P5. Note the missing tail-feathers and note also that the secondary moult has started as well.

The complete moult in the secondaries is normally initiated at the division between primaries and secondaries (S1, next to P1). The primaries are dropped in an almost constant interval, but moult in the secondaries may evolve much quicker: the first outermost secondaries (S1 to S3) are normally shed one by one with reasonable intervals, but the inner secondaries are almost dropped simultaneously, leaving large gaps in the inner-arm by the end of August.