Mediterranean Gull 6AY adult, February 06 2003, Le Portel /Boulogne-sur-Mer, France (50.42N,1.34E).

This individual is ringed: right white 6AY. From late summer to September, a complete moult takes place, bringing birds into so-called "adult winter" plumage. The head pattern in wintering bird resembles "first winter plumage" after finishing the complete moult: a blackish mask behind the eye. 

The next moult in Mediterranean Gull is again a partial moult, from January to April, and includes body and head, leaving birds in so-called "adult summer" plumage from early April onwards. The head develops a jet-black hood, extending down the nape. Adult birds have broad white crescents above and below the eye.

In this individual 6AY, the head pattern is extensive, although some birds may develop already half of the hood by late January. The mantle, scapulars, tertials and all the wing-coverts are plain pale grey. 
The secondaries are completely white. The adult primaries are shiny pearly-grey, flashing white at a distance. There is a black line along the outer-web of P10 (which is heavily reduced in this individual, but on P9 as well in some other birds). The secondaries, the under-wing and the tail are completely white. The bare part coloration by February: Iris brown, orbital ring red or orangey-red, the bill red or orangey-red with a black bill-band (and a yellowish tip) and the legs dull reddish or dark.

White 6AY was ringed as >3cy bird (adult) on May 25 1999 in the breeding colony of Zandvlietsluis at Antwerpen, Belgium (51.20N,04.17E). It was seen at this location during the summer of 1999 until July 04 1999, after which it was rediscovered five times at Le Portel, NW France (50.42N,01.34E) from July 31 1999 to February 09 2000. Early spring it reappeared at the same colony of Zandvlietsluis, Belgium, from April 11 to 14 2000. It then visited the breeding colony of Kreekrak Oost, the Netherlands (51.27N,04.14N). It's not clear whether it has raised a brood this summer, as it already returned to Le Portel to complete the moult from June 28 2000 to January 20 2001. During this period of seven months, it was seen 12 times.
Again, it reappeared at Zandvlietsluis, and was seen only one week (3 times) from April 14 to 21 2001. July 02 to October 11 2001 it was seen again at Le Portel. The entire summer was spend in the colony of Zandvlietsluis, from March 16 to July 13 2002. It was seen 20 times. From August 01 2002 until at least February 2003 it spend the winter months again at Le Portel.