Herring Gull (argentatus & argenteus)

(last update: February 11, 2013)

Herring Gull sub-adult, July 09 2013, Katwijk, the Netherlands.

4CY or 5CY bird, no ring, no provenance on origin and age.
Aged by vestiges of immaturity, most noticable dark markings in centres of the greater porimary coverts, in combination with adult-like pattern on primaries and secondaries. In particular note mirror on P9 and P10 which probably best indicate 5CY bird.
Active moult in primaries (complete moult in summer months): P2/P6, but P3 almost equal to P1 in length.