Herring Gull (argentatus & argenteus)
(last update: February 11, 2013)
Herring Gull argentatus KY61 2cy & 3cy, July 2009 & September 2010, the Netherlands.
Male. Ringed as pullus on July 13 2008 with plastic white KY61 and metal RUM Moskwa ES14440 at Sedlovataya Island in Kandalakshskiy NR , Murmansk, Russia (66,56N 32,4E). Project leader: Vitaly Bianki.
below: Herring Gull (argentatus) KY61 3CY, September 09 2010, Westkapelle, the Netherlands.
Obviously darker than local birds. Note pattern on tail, and rather 2nd gen like outer primaries (compare to local birds in second picture). P8 at length of P7.
below: KY61 3cy, September 15 2010, Westkapelle, the Netherlands. Pictures Pim Wolf.
P8 fully grown; central secondaries growing, innermost group of secondaries still 2nd gen. Huge bugger, double the size of local birds.
Obviously more immature in markings on coverts and scapulars than local birds. Note pattern on tail, and white tips to primaries.
From June to October, a complete moult
will bring 3cy argentatus in so-called "third winter"
plumage. By August, the first neat streaks can be found on the crown and
neck. After the complete moult is finished in autumn, the head will show
extensive 'winter streaking', often neat fine streaking in argentatus and mottled brown contrasting with the white breast as in an executioner's
hood in many argenteus. The scapulars and mantle are pale
adult-like grey, although some individuals may show an immature pale brown
hue or arrow-head patterns on the lower scapulars.
During the summer, the primaries are moulted to third generation. In argenteus, 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 late-October, in argenteus, when the new outer primary P10 is fully grown. Preliminary data from Tampere, Finland, indicate 3cy argentatus from this region are not delayed in primary moult compared to argenteus from continental NW Europe. The third generation primaries are clearly adult-like, with inner primaries P1-P3 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 black sub-terminal markings. The white primary tips are obvious in the inner primaries, but are only poor developed on third generation P9 and P10. The third generation P10 normally shows a small white mirror (lacking in some birds). The new tail-feathers will be predominantly white, with clear immature black markings. The iris turns pale yellow in summer in most argenteus (July-August), but quite some argentatus will keep the iris amber to dark brown.
In the tables below, the primary moult scores of 3cy July argentatus in Finland can be read:
The differences between typical
western argenteus from the U.K. and northern Scandinavian argentatus is rather straightforward on primary pattern P5-P10. However, there
is a gradient and overlap in features of birds from populations in
northern Germany, Denmark and southern Norway.
Baltic argentatus often have the black marking on P5 confined to the outer-web as a single rectangular small black square, with well-defined borders (not diffuse as in most Finnmark birds). In most Baltic birds, the white tip of P10 fully merges with the mirror, without a single sign of a sub-terminal band. The greyish-white 'tongue' on the inner-web is often broad and continues far down P10, almost creating a thayeri pattern on P10. The shape of the division line between greyish tongue and black outer-web can be an identification clue: In cachinnans this division line often makes a strong angular curve and has a smooth straight line, unlike the pattern of Herring Gulls, which often show a "saw-blade" motive or otherwise much irregularities along the division line. Sometimes wear of the outer primaries may be useful as a first indication of origin: An early moulting species as cachinnans on average show more abrasion in the feathers than later moulting argentatus.Extensive research on the P10 pattern of Scandinavian argentatus was done for Norwegian birds by the Norwegian ornithologist Edvard Barth, and is presented in the table below.
Especially birds from north Scandinavian Finnmark may show the characteristic 'thayeri' pattern in the outer primaries P9 and P10 (column 5 of tip pattern P9 in the table). This pattern is named after the Thayer's Gull, which often shows a particular pattern in the outer primaries: the mirror and the white tip merge and are connected to the pale inner-web (see this image). In other words: the black medial band of the outer-web doesn't fully reach the edge of the inner-web and there is no sub-terminal band. In Thayer's Gull this pattern may be very obvious and, together with the 'string of pearls' may be indicative for identification.
below: 2cy KY61 (argentatus) July 31 2009, Scheveningen, the Netherlands. Pictures: Mark Zevenbergen.P6/P9.
below: 2cy KY61 (argentatus) July 31 2009, Scheveningen, the Netherlands. Pictures: Maarten van Kleinwee.Record-shot of second-calendar year Herring Gull of subspecies argentatus. Note the large bulky size and relatively small head. The scapulars and tertials have been replaced to second-generation feathers, including some of the inner median and greater coverts. The outer primaries are still juvenile. The bill is extensively pink.