Herring Gull (argentatus & argenteus)

(last update: February 11, 2013)

Herring Gull (argenteus) A3MM 1CY-6CY, November 2006 - February 2011, Oostende, Belgium.

1cy argenteus, ringed in Hastings, S England. Picked up as juvenile, and released on 14 July 2006 at Pett Level, East Sussex.

below: Herring Gull (argenteus) A3MM 1CY, November 26 2006, Oostende, Belgium.

A bird with all the scapulars moulted to second generation feathers. Some wing-coverts were replaced in the left wing as well, something not seen very often in Herring Gull (app 1:40 birds = 2.5%).

The partial autumn moult in argenteus (moult from juvenile plumage into so-called "first winter" plumage) includes the 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, the mantle and upper scapulars are 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 (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.

below: Herring Gull (argenteus) A3MM 1CY, December 06 2006, Oostende, Belgium. Pictures Walther Leers. 

below: Herring Gull (argenteus) A3MM 2CY, January 31 2007, Oostende, Belgium. Pictures Walther Leers. 

below: Herring Gull (argenteus) A3MM 2CY, February 23 2007, Oostende, Belgium. Pictures Ies Meulmeester. 

below: Herring Gull (argenteus) A3MM 6CY, February 13 2011, Oostende, Belgium. Picture: Peter Adriaens.