Just for reference: comparison of primary patterns in adult Dutch Herring Gulls, all from different individuals, mix of male and female.
Details to look out for are:
- Presence, absence and shape of mirror on P9/P10
- Amount and shape of black mark/band on P5/P4
Images were taken during ringing activities in the IJmuiden Forteiland gull colony, the Netherlands, May – June 2018.
Click for a larger view.
Gulls to the Horizon 