Herring Gull- Zilvermeeuw (argentatus & argenteus)

(last update: 20-2-2007)

Herring Gull H-117461 3cy (argenteus), April 06 2004, Westkapelle, the Netherlands (51.33N - 03.25E). Picture Pim Wolf.

3cy argenteus has a partial moult in spring. It starts in January and is completed by April, leaving birds in so-called "second summer" plumage. The head turns white, especially on throat, breast and belly. By April, the scapulars and mantle will show many adult-like grey feathers, creating a contrasting "grey saddle" in many birds, as most of the wing-coverts (especially the lesser coverts) are still barred. The wing-coverts start to fade and the fringes wear away.
The iris and base of the bill turn pale yellow, although some individuals still show a warm amber iris. The bill will show some red on the gonydeal angle and an obvious dark bill-band. 

The image presents a typical argenteus, with an obvious grey saddle. The brown second generation primaries are slightly bleached and lack a mirror on P10. The second generation tail has a broad dark tail-band.
This individual has moulted some wing-coverts to third generation grey feathers in the partial autumn moult as a 2cy bird; note especially the upper tertials, median and lower lesser coverts.