Black-headed Gull Chroicocephalus ridibundus

(last update: 3-04-2011)

Below: First-calendar year Black-headed Gull, August 18, 2009, Grote Dobbe, Zoetermeer, The Netherlands (52.059N, 4.494E). Photos: 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 is now almost completely white and the brown markings on the head and hind neck have started to fade. The scapulars still show predominantly first-generation, juvenile brown feathers, while the scapulars have been mostly 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). In the lower image, not the dark markings in the outer web of P6-P10, parts of which can be retained in later years.