Lesser Black-backed Gull L f graellsii
1, 3: © Ruud Altenburg, 09-07-05; 2: © Ruud Altenburg, 04-07-05; 4: © Theo Muusse, 09-07-05. Amsterdam, Netherlands.
NLA 5.412.281, from IJmuiden, is a graellsii showing predominantly barred feathers. A fast moulting individual: by early July, P1-4 are fully grown, P5 is growing and P7-10 are still juvenile. There is active moult in the tail and secondaries, so it is impossible to determine with certainty if the new feathers (rectrices and two inner secondaries; see plate 4) have recently been acquired or were moulted in some time ago on the wintering grounds. All wing coverts and tertials have been replaced; some greater coverts are not yet fully grown. Birds of this type can potentially be confused with Yellow-legged Gull. Structurally it differs from typical heuglini, with a heavy bill and more stocky appearance.