Herring Gull- Zilvermeeuw (argentatus & argenteus)

(last update: 9-2-2007)

Herring Gull 4.xxx.xxx 3cy (argenteus), March 05 2004, Amsterdam, the Netherlands (52.21N - 04.52E). Picture Ruud Altenburg.

3cy argenteus, ringed on Helgoland, Germany. 3cy Herring Gull 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 argenteus, in the clinal zone towards argentatus. In general, birds may look less advanced, lacking an obvious grey saddle, and with the under-parts and head still largely in winter plumage (i.e. much blotching and specling). The bill is not as typical for 3cy birds in March, which is normally pinkish based with a broad bill-band; here it looks less advanced. Note the rather neat second generation primaries lacking the mirror on P10. The tail is completely second generation, showing a broad band. Typical north-Scandinavian argentatus also show an almost second generation-like scapular region with only single grey feathers. The partial autumn moult in 2cy didn't include tertials nor coverts in this bird.