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 a delayed moulting individual, delayed in primary moult score compared to average 3CY michahellis.

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: P7-10 are old second generation and P4 is full-grown. The landing bird is a 3CY Lesser Black-backed Gull, showing a small gap in the primaries (not uncommon in LBBG), with P6 almost fully grown and P8-P10 still old second generation.