Herring Gull- Zilvermeeuw (argentatus & argenteus)

(last update: 30-9-2009)

Herring Gull (argenteus) 1cy SR September 17 2013, Katwijk, the Netherlands.

Local bird ringed metal Arnhem NLA 6.173.939 and tibia blue SR, ringed as pullus (sex unknown) on July 06 2013 at Maasvlakte ((Tennesseehaven), Zuid-Holland, NL (5158.00 N, 405.00 E), by ringers H. Keijser & R.J. Buijs.

US=1-25%, LS=0%, TOT SCAPS=1-25%.

The partial autumn moult in argenteus (moult from juvenile plumage into so-called "first winter" plumage) includes the scapulars, body and head feathers. This moult starts as soon as the nest is abandoned (late June) and continues until January. In general, the head turns paler on throat and forehead. The breast will turn paler as well. The feathers on belly and vent will still be juvenile in most 1cy argenteus by November. From July onwards, juveniles replace the mantle and upper scapulars, moulted to second generation feathers, showing an anchor pattern and a dark base. The lowest row of scapulars are still juvenile by March in most 2cy birds from northern origin (contra e.g. michahellis).

The notched pattern of the juvenile scapulars is repeated on the juvenile lesser, lower lesser and median coverts, although the medians have paler centres. The juvenile greater coverts show a 'piano-key' pattern; on the outer greater coverts as well. The tertials have an obvious notched pale fringe and transversal bar. 
The juvenile wing-coverts, rectrices and remiges start to bleach and show wear in the fringes from September onwards. The secondaries, primaries and primary coverts are dark with a small white tip, but the juvenile inner primaries show an obvious pale window, prominent from below and above. The under-wing is rather uniform grey-brown patterned. The tail has a broad sub-terminal band and isolated dark bars on the basal half. The iris is dark, the bill is blackish, sometimes with a paler base, and the legs are flesh-pink.

Recoveries
17-9-2013 Katwijk aan Zee (Strand), Zuid-Holland, NL 5.213,00 N 424,00 E colourring read Frank van der Meer
17-9-2013 Katwijk aan Zee (Strand), Zuid-Holland, NL 5.213,00 N 424,00 E colourring read Mars Muusse