Gull 3cy, October 20 2003, IJmuiden, the
P1-P9 are fully grown, P10 at the length of P9 with a small mirror. All
rectrices fully grown with vermiculated black markings. Most of the greater coverts show an obvious barred pattern.
From June to October, a complete moult
will bring 3cy argenteus in so-called "third winter" plumage.
By October, when the complete moult is finished,
the head will show extensive 'winter streaking', mottled brown contrasting
with the white breast as in an executioner's hood. The scapulars and
mantle are pale adult-like grey.
By the end of the complete moult (October), all wing-coverts have been
replaced, most to plain grey feathers. Immature patterns can often be
found in the lower tertials, greater coverts and outer lesser coverts (the
During the summer, the primaries were moulted to third generation. The
first inner primaries are dropped by late May and the outer primary P10
will be dropped by late August. The primary moult is completed by
when the new outer primary P10 is fully grown. 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 pale brown-yellow.