Lesser Black-backed Gull RC9 6cy, April 22 2002, Missouriweg - ECT, Maasvlakte, the Netherlands (51.59N,04.02E). 

An adult ringed, left orange with a white code RC9. Note the rather small mirror on p10. The upper mandible has a diffuse black streak and a pale tip. The wing-coverts, tertails and scapulars look very neat and tidy, without a single moult gap. The inner median and inner greater coverts are slightly worn with a first indication of a brown hue. Ringed July 1997.