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

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 also included some wing-coverts and tertials: In the left wing, the upper tertials #1-3, inner greater coverts #1-4, inner and central median coverts, inner and central lower lesser coverts and about eight 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 last moulted feathers (e.g. central median and lower lesser coverts) show broad white tips and grey bases. The tail-feathers and flight-feathers are still juvenile, except one rectrices on the right-hand side. Since the tail is closely folded, it seems to be predominantly dark, but this only applies to the central rectrices.
Fresh scapulars with a broad pale tip can be found in the rear lower scapulars. Its difficult to tell exactly how many upper scapulars have been replaced recently for third generation feathers. 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.

March 16 2003

March 17 2003

March 18 2003