Herring Gull - Zilvermeeuw (argentatus & argenteus)(last update: 08 december 2003) |
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Herring Gull ??0300 adult (argentatus), August 12 2002, Tampere, Finland (61.31N,23.43E). An adult argentatus, metal-ringed Luthania - Estonia ??0300. Note the slight dark cast over the yellow iris and pinkish legs. This individual is in active complete moult with the outer median coverts replaced, the outer greater coverts growing and the lower lesser coverts shed. The outer primaries P8-P10 are still old, with a large mirror on P10. The P10-mirror completely merges with the white tip. Note the coral-red orbital ring and the rather pale grey upper-parts. From June to December, adult argentatus
undergo a complete moult resulting in so-called "winter
plumage". By August, the first
neat streaks can be found on the crown and hind-neck. After the complete moult is
finished by late autumn, the head will show extensive 'winter streaking', often
neat fine streaking in sub-adult argentatus. During the summer, the primaries are moulted. In adult argentatus, the last outer primary P10 will be fully grown by January (but also early December in southern populations?), a few weeks later than in West-European argenteus. First data from Tampere, Finland, indicate that 3cy argentatus from this region are not delayed in primary moult compared to argenteus. Adult northern argentatus show a different
pattern in the outer primaries, compared to argenteus. In
argentatus, especially from northern Scandinavia, the black marking
on P5 is very limited and, if black on P5 is present, this black has
diffuse edges. But often, these black sub-terminal markings are completely
lacking on P5. In Baltic argentatus populations, black on P5 is confined
to the outer-web, with sharply defined edges. The iris is clearly yellow in summer in most argentatus, but some sub-adult argentatus will keep the iris amber to dark brown. |