Herring Gull- Zilvermeeuw (argentatus & argenteus)

(last update: 9-2-2007)

(2 images) Herring Gull H-124999 3cy (argenteus), March 29 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. 

These images present a typical argenteus, with an obvious grey saddle, but with the under-parts and head still largely in winter plumage (i.e. much blotching and specling). The bill is typical for 3cy birds in March, pinkish base and a broad bill-band. Note the rather brown second generation primaries lacking the mirror on P10. The tail is completely second generation, showing a broad band. Compared to Scandinavian argentatus, the general impression resembles argentatus in 4cy, which also show an almost complete grey scapular region and single grey feathers in the tertials, inner greater coverts and a few lesser coverts. 

P1-P10 are still old 2nd generation. This individual has moulted very few wing-coverts to third generation grey feathers in the partial autumn moult as a 2cy bird. This argenteus was ringed in Belgium, Bruxelles H-124999. As soon as ring data are available, this information will be added.