Herring Gull- Zilvermeeuw (argentatus & argenteus)

(last update: 8-2-2007)

(2 images) Herring Gull 3cy (argentatus), January 04 2002, Le Portel / Boulogne-sur-Mer, France (50.42N,1.34E).

A 3cy argentatus, which is very coarsely marked and contrastingly patterned. The new scapulars are not plain adult-like grey as in most argenteus, but the scapular region are moulted to third generation feathers which strongly resemble the second generation feathers. Consequently, 3cy argentatus may look very delayed in their moult, compared to argenteus in mixed groups and they can sometimes be mistaken for 2cy birds.
However, note the primaries with rounded tips, clearly second generation feathers and unlike the pointed juvenile remiges. Looking closer, P10 shows a faint mirror, a feature definitely lacking in juvenile feathers. Second generation primaries with a mirror on P10 can be found in quite some argentatus (and is very rare in argenteus).

This individual has replaced very few wing-coverts in the partial autumn moult as 2cy bird: greater coverts #2-3 and probably a single lower lesser covert have been replaced. The new feathers show a buffish hue on the pale parts and have fresh fringes and tips.