Aves, p�le ornithologique de Natagora

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Aves, 21/1 | 1984 | 24-32

  Numerical evolution since 1960 of migration forest birds wintering in Western Europe.
Przemyslaw, B.

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Article summary

Survey of variations in effectives of migrating birds captured in research stations situated on the polish coast (816.420 birds comprising 142 different species captured from 1960 to 1982). Proof of long term changes is difficult due to normal annual fluctuations requiring statistical adjustment; account must also be taken of all differences, sometimes considerable, in the variations observed in the various stations, which may be frequented by one single or several distinct populations. During the course of these 22 years, certain species exhibited a cyclic evolution, others were in constant diminution, and others cyclic variations with general progressive diminution. All species taken together, a cyclic evolution with diminution of the effectives in the various stations was found.

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