Adult American Herring Gulls from Massachusetts, USA
This gallery shows adult American Herring Gulls from Massachusetts, USA. All pictures were taken in January and February. The goal of this page is to show the variability of some of the key id features (general appereance, bill shape and pattern, extension and density of head patterning, presence of bayonettes on primaries, extension of black and white on p10). American Herring Gulls from New Britain are more sedentary than Arctic birds (see here) and thus likely less prone to end up as vagrants in Europe, but note that other American gulls such as Ring-billed Gull and Laughing Gull also present a southern distribution and short-distance migrations and are still rather frequent in Europe.
Note that the birds shown in the first paper by Lonergan & Mullarney (2004) (mainly focused on 1w and 2w birds) belong to the same population as the ones shown here, whereas the Adriaens & Mactavish (2004) (focused on adults) paper analysed birds from Newfoundland, Canada. Among other features, these ‘southern’ American Herring Gulls are smaller, look more elegant (not as much Great Skua-like) than arctic birds, and they also show much more extensive black on the primaries. Birds showing reduced bayonetes and black on p10 going all the way up to the primary coverts, and lacking the white squared tongue on the underside, aren’t rare.
Something important to bear in mind when judging a putative smithsonianus in Europe, at least in southern Europe where argentatus is scarce/rare.
