Herring Gull - Zilvermeeuw (argentatus & argenteus): sub-adult February

(last update: 08 december 2003)

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Herring Gull 4cy (argenteus), February 04 2002, IJmuiden, the Netherlands (52.27N-04.33E). 

This 4cy argenteus still shows many markings on the tertials and on the the greater coverts. It shows a typical immature bill and much streaking on the head. On the other hand, it also shows some adult features, as most of the scapulars and coverts are adult-like grey and there is an obvious mirror on the third generation primaries P10. The outer primaries show white (although relatively small) tips. Note the dark brown outer primary coverts.

From January to April, 4cy argenteus moult to so-called "third summer" plumage. By April, the head and under-parts will appear all-white. The tail-feathers, wing-coverts and primaries are not replaced, therefore most birds strongly resemble "third winter"  birds, although the white primary tips wear away and dark patches start to bleach. The iris is often yellowish, the orbital ring yellowish-orange and the bill predominantly yellow with a red gonydeal spot and limited black markings along the culmen by April.