L. michahellis: adult November & December

General description:

Moult in the wing coverts:

Average adult michahellis have finished the complete and partial wing-covert moult by the end of October and moult is normally suspended throughout November and December. A few birds which were mouling the inner median or inner greater coverts may just finish this moult by early November. By the end of December, most birds show wear in the coverts again, most noticeable at the inner coverts.
Single feathers of the scapulars may be missing and some birds may continue moult in this tract at a very low pace.

Moult in the remiges and rectrices:

Early November it's still possible to find adults with P10 not fully-grown; in these birds primary P10 has to grow an inch or two. Rectrices and secondary moult was finished by the end of October. 

Moult of the body feathers:

The body feather moult was finished in September. As can be seen in the image from November, the feathers on the head may show obvious streaks, although this bird from Britain is extraordinary in the amount of streaking. Normally adult michahellis start to turn completely "white-headed" by December. 

Bare parts:

In full adult michahellis, the colour of the legs hardly turns paler in winter. There may be some dark markings on the cutting edge of the bill or on the gonydeal angle in otherwise full adult birds.

Yellow-legged Gull (michahellis) 19cy & 21cy C 53597August, September & November, Boulogne-sur-Mer, NW France. Picture: Jean-Michel Sauvage.