Ardea
Official journal of the Netherlands Ornithologists' Union

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Bilcke G. (1984) Residence and non-residence in passerines: dependence on the vegetation structure. ARDEA 72 (2): 223-227
Counts of passerine birds in nine different habitats have shown that the proportions of resident, Mediterranean migrant, and tropical migrant individuals were significantly correlated with the vegetation structure, showing that migrants are more abundant in open vegetation, while residents prefer the woodlands. Likewise, considering all Belgian passerine species, migration distance decreases from open habitat to forest. In contrast, literature data show that in the New World the migrants and residents are about equally abundant in open habitats and forests. Since the two existing hypotheses can only explain the European but not the American situation, I propose the alternative hypothesis that the proportion of migrants in their breeding areas is determined by the occurrence and geographical distribution of different vegetation types in their winter quarters.


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