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 2CY, March 17 2003, Etaples/ Boulogne-sur-Mer, France (50.42N,01.34E).

A strong and powerful 2CY michahellis, which has replaced the head, neck, breast, belly and flanks to second generation in the first pre-basic moult (post-juvenile moult). The vent is still juvenile. This moult included only few wing-coverts and no tertials: inner median coverts and central lower lesser coverts have been replaced for second generation feathers. By March, the exact sequence is very hard to detect as the juvenile wing-coverts are very abraded and bleached and the second generation wing-coverts required in an early stage (July-August) are very hard to separate from old juvenile feathers. The other wing-coverts, the tail-feathers and flight-feathers are still juvenile.
Fresh scapulars with broad pale fringes can be found in the lowest scapulars. Its difficult to tell exactly how many upper scapulars have been replaced recently for third generation feathers, but a few obvious feathers are visible in the central lower upper scapulars. In 2CY michahellis it's common to find birds starting to replace upper scapulars to third generation feathers, while the rear lowest scapulars have only very recently been replaced for second generation feathers. By this stage, this individual shows first generation feathers (remiges, rectrices, most outer wing-coverts), second generation feathers (the head, body, most scapulars and some inner wing-coverts) and at the same time third generation feathers (a few lower upper scapulars).
Note that in most 2CY individuals of this age-class the head and neck are by no way pure white, with delicate dark streaking concentrated around the eye and extending on the nape. In the hind-neck, 2CY michahellis often shows a boldly streaked neck-collar. The dark bill starts to turn paler at the base by February.