Mew Gull Larus canus canus; heinei; kamtschatschensis; brachyrhynchus

(last update: March 12, 2012)

Kjeld Tommy Pedersen (Denmark)
Chris Gibbins (Scotland)
Frank Majoor (Netherlands)
Mars Muusse (Netherlands)

Mew Gull canus E419 adult, June 22 2003, Dintelhaven, Maasvlakte, the Netherlands.

An individual at the start of the complete moult. The tertials and inner wing-coverts are very worn by mid-summer. From early summer to October, a complete moult will bring birds in so-called "adult winter" plumage. The head is still white but the new head feathers will show streaks or spots, most densely in the hind-neck and the bill will show a (faint) bill-band. The under-parts, tail-coverts and rump will stay white. The upper-parts are medium grey, with broad white fringes on the tertials. The adult primaries have a clear-cut black triangle on the outer-wing. Black sub-terminal markings run down to P6 or P5. From P1-P9 the primaries show extensive white tips and the two mirrors on P9 and P10 are obvious (there may even be a small mirror on P8). The iris is brown in nominate canus, the bill is yellowish with a faint black bill-band and the legs are yellowish, greenish or greyish, often with a flesh-cloured hue.
In adult winter, brachyrhynchus develops only diffuse head streaking, creating a diffuse grey head and no dark bill-band, whereas canus often has the head strongly mottled or streaked and often develops a full bill-band in winter. Furthermore, the iris in brachyrhynchus is paler, sometimes clear yellow. Adult brachyrhychus normally have a black sub-terminal band on P5-P10. Between this black band and the grey centre, a large white spot is visible both from above and below on P5-P7, creating a string of pearls on these primaries. P9 and P10 show large white mirrors.