Herring
Gull - Zilvermeeuw (argentatus & argenteus): sub-adult April
(last update: 24 maart 2005)
Home
Links
to Gull Sites
Gull Taxa
Gull Topography
Grey & Colour Charts
Locations in NW Europe
Summaries of Articles
About ORG
@
Herring Gull 5.364.712 4cy (argenteus), April 09 2004, Westkapelle, the Netherlands (51.32N 03.26E). Picture Pim Wolf.
A 4cy argenteus with Dutch ring. This argenteus shows all the familiar characteristics of a 4cy in spring:
- the small white mirror on P10,
- the white tips of the third generation primaries are relatively small compared to adult primaries in argenteus Herring Gull,
- the tail has obvious vestiges of immaturity,
- the tertials have much brown patterning; this can also be seen in median and greater coverts,
- a combination of completely adult-like scapular and mantle region and patterned (barred) greater, median and lesser coverts,
- the extensive dark bill-band, dark orbital ring and greyish iris.
From January to April, 4cy argenteus moult to so-called "third summer" plumage. The head and under-parts will appear all-white by early May. The tail-feathers, wing-coverts and primaries are not replaced in this moult, 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 in argenteus and the bill predominantly yellow with a red gonydeal spot and limited black markings along the culmen by April.