Primary pattern variation in adult Herring Gull Green YBKC from 2015 to 2018

Suspended primary moult in adult European Herring Gulls Larus argentatus argenteus of the Dutch colony of IJmuiden Forteiland

Uitgestelde handpenrui bij volwassen Zilvermeeuwen Larus argentatus argenteus uit de IJmuiden Forteiland kolonie

4CY Presumed hybrid Lesser Black-backed Gull x Yellow-legged Gull Green YBWP – 20180409

Marked Birds Database update: plans for the coming months

Marked Birds Database – Version 1.16.1 available

Status update on the presence of pseudo-mirrors and non-isolated mirrors in IJmuiden-ringed adult European Herring Gulls

Status update over de aanwezigheid van pseudo-spiegels en grijze inkepingen bij adulte Zilvermeeuwen van IJmuiden Forteiland

First returning Lesser Black-backed Gulls in Leiden – 20180223

Mixed breeding pair Herring Gull x Lesser Black-backed Gull in IJmuiden 2017