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, August 25 2000, Etaples / Boulogne-sur-Mer, NW France.

Primary moult score: P8 is fully grown, P9 has to grown a few inches and P10 is halfway it's final length. Another example showing the secondary moult stage. By July, most of the secondaries have been shed (click the thumbnail for the secondary moult stage of July michahellis) but in the majority of the birds, a small block of juvenile secondaries remain at the inner half of the arm. Secondaries are moulted in descendant order, S1 is the first moulted feather (the outermost secondary) and in a wave, new secondaries grown inwards. The two or three innermost secondaries, often hidden by the tertials, are moulted simultaneously and finally the small block of juvenile secondaries is shed as well. Now, by the end of August, it's this group of secondaries which are renewed last in line and as can be seen in the left picture, the gap is closed from two directions.
The complete tail has been replaced. Note the gap in the central median coverts and the outermost greater coverts which is still growing. All second generation secondaries show a neat dark centre and a white zigzag pattern created by the neat white fringes. Note the grey scapulars and the predominantly white upper-tail coverts, contrasting with the broad tail-band. The second generation inner primaries show a window, which is more obvious in 2CY than it is in 1CY, but still not as well-defined as in argenteus Herring Gull.