IJmuiden Project - Fred Cottaar, José Verbeek, Maarten van Kleinwee & Mars Muusse

(last update: January 01, 2023)

Herring Gull (argenteus) Y.APF adult, August 2010, IJmuiden, the Netherlands. Picture: Mars Muusse.

Ringed as breeding adult on May 14 2010 at Forteiland, IJmuiden. Ringed by Fred Cottaar ringing team.

below: Herring Gull (argenteus) Y.APF adult, August 24 2010, IJmuiden, the Netherlands. Picture: Mars Muusse.

From June to December, adult argentatus undergo a complete moult resulting in so-called "winter plumage". By August, the first neat streaks can be found on the crown and hind-neck. After the complete moult is finished by late autumn, the head will show extensive 'winter streaking', often neat fine streaking in sub-adult argentatus. 
By the end of the complete moult (sometimes mid-January in argentatus), the scapulars, mantle, all the wing-coverts, rectrices and remiges will be replaced. From June onwards, the new plain grey wing-coverts are moulted in, starting with the outermost median coverts. 

P8-P10 still old.

below: Herring Gull (argenteus) Y.APF adult, August 13 2010, IJmuiden, the Netherlands. Picture: Mars Muusse.

P7-P10 old.