Herring Gull - Zilvermeeuw (argentatus & argenteus): sub-adult April
(last update: 08 december 2003)
(2 images) hybrid Herring Gull x Yellow-legged Gull 4cy EV65 (argenteus x michahellis), April 02 2000, Neeltje Jans, the Netherlands. Pictures by Pim Wolf.
EV65 was born in the Netherlands and
as pullus on June 21 1997. As soon as
data are available, more information about this bird will be added.
characteristics advocate a hybrid. The
photographs are from the colony, where EV65 is surrounded by local
Dutch argenteus. Note the relative tone of grey, compared to these
local Herring Gulls. Another clue is the colour of the legs, which is
slightly orangey-pink, unlike the whitish-pink or greyish-pink legs of argenteus.
From January to April, both 4cy argenteus and michahellis moult to so-called "third summer" plumage in a partial moult. This partial moult involves head and body. By April, the head and under-parts will appear all-white, as this individual clearly shows. The third generation tail-feathers, outer wing-coverts and primaries are not replaced; therefore most birds strongly resemble "third winter" birds in this respect, although the white primary tips wear away and dark patches start to bleach. The third generation primaries are clearly adult-like, with the inner primaries P1-P4 plain grey with a white tip. The outer-wing shows a clear black triangle, extending on the greater primary coverts. From P4 outwards, the primaries show a black sub-terminal band. The white primary tips are obvious in the inner primaries, but often smaller on P9 and P10. P10 has a small white mirror (lacking in some birds). The new tail-feathers will be white, with clear immature black markings. The iris is often yellowish (with dark speckling and the iris is obviously peppered in this individual), the orbital ring yellowish-orange in argenteus (but coral red in this bird) and the bill predominantly yellow with a red gonydeal spot and limited black markings along the culmen by April.