Black-headed Gull Chroicocephalus ridibundus

(last update: 3-04-2011)

Below: First-calendar year Black-headed Gull E4KP, July 27, 2010, Grote Dobbe, Zoetermeer, The Netherlands (52.059N, 4.494E). Photo: Maarten van Kleinwee.

First-calendar year Black-headed Gull, moulting to first-winter (formative) plumage. In this post-juvenile moult, all feathers are replaced except those on the wings and in the tail.

In this individual, the body has turned completely white and the brown markings on the head and hind neck have started to fade. Most of the scapulars and mantle feathers have been replaced by gray, second-generation feathers. The outer tail feathers show dark markings on the inner web (the norm is a fully dark tip on T6, while on a minority T6 is completely white).

This individual was ringed as part of the Dutch RAS project (Recapturing Adults for Survival; research on survival of Dutch breeding birds).
For more information about the RAS project, visit http://frankmajoor.nl/kokmeeuwen-broedvogels1-uk.shtml.