HIGLER LWG (1962) Census of the Black-headed Gull Chroicocephalus ridibundus Larus ridibundus in Belgium, the Netherlands and Luxemburg, 1961. LIMOSA 35 (3): 260-265.

Black-headed Gull Chroicocephalus ridibundus = Larus ridibundus In 1961 the RIVON. (State Institute for Nature Conservation Research) in Bilthoven, Netherlands, made a census for the black-headed gull (Larus ridibundus 1..) in Belgium, the Netherlands and Luxemburg. The species does not breed in the southern provinces of Belgium and in Luxemburg. In the Netherlands and the northern provinces of Belgium, the black-headed gull is numerous as a breeding species. It has increased in numbers in this area during the first decennia of the twentieth century, as it did in England and Wales, Denmark, Norway, Sweden, Finland and France. The sketch map of the Netherlands shows the localities of the breeding-colonies in 1961. The Benelux sketch map and table I give the numbers of breeding pairs per province

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