ZIJLSTRA M (2003) Flevoland, the last stronghold for the Hooded Crow Corvus cornix in the Netherlands. LIMOSA 76 (2): 49-58.

New polders offer the opportunity to study the development of flora and fauna. In particular the development of breeding bird communities has been studied, while wintering birds have received less attention. In Eastern and Southern Flevoland, embanked in 1957 and 1968 respectively (Fig. 1), the development of the population of the migratory Hooded Crow and the sedentary Carrion Crow C. corone was studied between 1977-2000 in relation to landscape development. In the early days of the newly developed agricultural land in the polders the landscape was barren and largely lacked buildings and trees. In those days the Hooded Crow outnumbered Carrion Crow in winter. With the development of the landscape it became more attractive to the territorial Carrion Crow. From 1977 onwards the percentage of Hooded Crows decreased and Carrion Crow increased (Tab. 1, Figs. 4, 5). In about 30 years time the length of stay of the Hooded Crow in winter decreased with about one and a half month as a result of later arrival in autumn and earlier departure in spring (Fig. 2). About 30-40 years after the embankment the Hooded Crow disappeared from the polders entirely. The disappearance started earlier in the polder that was embanked last but took less time in the oldest polder. The growing suitability from the landscape for the territorial Carrion Crow and the diminishing food supply are thought to be factors important for the disappearance of the Hooded Crow from the Flevopolders, along with factors like the northwards moving boundary of the wintering area in general.

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