Images taken during a visit to the gull colony of IJmuiden Forteiland, the Netherlands, on April 15, 2019, as part of our research project.
Shown are European Herring Gulls and Lesser Black-backed Gulls.
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European Herring Gulls
With a pseudo-mirror on P9 in the left wing (not present in 2018).
With partner YCAP:
With partner YCMN.
With thayeri-pattern on P9.
Lesser Black-backed Gulls
With strikingly dark legs each year.