Dintelhaven - Maasvlakte, the Netherlands, April 29 2002.
An adult bird ringed left green ES98, ringed as pullus at the nest, June 26 1996, now 7cy. The primary tips are fresh. P9 shows a white mirror as well, although the head-shape indicates a female. Note the dark spot on the upper mandible. Note also the difference in age in the tertials, with a fresher, plain grey second tertial between the brown hued feathers. In this case, the code of the ring turned slightly yellow.
Dintelhaven - Maasvlakte, the Netherlands, June 02 2003.
Nesting at the same location as the previous year, now in 8cy. ES98 has a clear yellow iris, without speckling, a red orbital ring, a red gonydeal spot confined on the lower mandible, no black on the bill by June 02, but still a whitish tip of the bill and it has a mirror on both P9 and P10. The complete moult hasn't started yet, with P1 still present.
2 images below: 9cy ES98, Dintelhaven - Maasvlakte, the Netherlands, April 13 2004.