Ardea
Official journal of the Netherlands Ornithologists' Union

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Walters J. (1978) The primary moult in four gull species near Amsterdam. ARDEA 66 (1-2): 32-47
In the Amsterdam-Zandvoort area in the Netherlands in 1976 and 1977 a study was conducted on the primary moult in Black-headed Gulls, Common Gulls, Herring Gulls and Great Black-backed Gulls. Two methods were used: registration of primary moult score in recently dead gulls and collection of newly shed primaries. Special attention is paid to the identification of the primaries. A detailed description of the timing of the primary moult in adults and sub-adults is given. The average duration of the primary moult was 3 months in adult Black-headed, 4+ months in adult Common and 6 months in adult Herring Gulls. Sub-adults were earlier and had a shorter moulting period: 2+ months in Black-headed Gull and 4+ months in Herring Gull. The onset of the primary moult was not known for the Great Black-backed Gull, not breeding in the Dutch area, for the other three species earliest in the Herring Gull, slightly later in Common Gull and latest in Black-headed Gull. Practically all adult Herring Gulls started primary moult during the incubation of the eggs, much fewer adult Common Gull and practically no adult Black-headed Gull did so. The finish of the primary moult was earliest in adult Black-headed Gull, slightly later in adult Common Gull, still later in adult Herring Gull and latest in adult Great Black-backed Gull (until early January by the latest). Recent literature on the primary moult in gull species in northwest Europe combined with the present study does not present enough material from which definite conclusions on .any ecological or geographical differences can be drawn.


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