The picture below is of Dutch European Herring Gull YDAP, seen on April 29, 2024, showing the primary pattern of its left wing. The primary pattern in the inset looks very different but is of the same bird from 2020… (click for a larger view) Note the large differences in the pattern on P10, P9, …
Large primary pattern variation in Dutch Herring Gull YDAP over multiple seasons
Gulls to the Horizon 