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Conserving the endemic birds on the Comoro Islands, II: population fluctuations on Ngazidja

Published online by Cambridge University Press:  11 May 2010

Jan Stevens
Affiliation:
Provinciaal Natuurcentrum, Zuivelmarkt 33, B-3500 Hasselt, Belgium
Marc Herremans
Affiliation:
Department of Wildlife and National Parks (Ornithology Section), P.O. Box 131, Gaborone, Botswana
Michel Louette
Affiliation:
Koninklijk Museum voor Midden-Afrika, B-3080 Tervuren, Belgium
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Summary

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Land bird abundances on Ngazidja, Comoro Islands, obtained by point counts in September 1985 and November–December 1989 are compared. The overall abundance of most species did not differ significantly. Most differences can be interpreted as normal within-year fluctuations. Some important changes are identified and attributed to shortterm vegetation changes: increase of Columba polleni, Coracopsis vasa, Zoonavena grandidieri, Coracina cinerea in Nioumbadjou after abandonment of forest exploitation; decrease of Coracina cinerea at M'Lima Mani North after replacement of the natural shrub layer by bananas. Genuine long-term population changes occur in Coracopsis nigra (increase) and Corvus albus (decrease).

Il s'agit d'une comparaison entre les abondances d'oiseaux terrestres, relevées sur Ngazidja, îles Comores, au cours de comptages par points effectués en septembre 1985 et novembre-décembre 1989. L'abondance générate de la plupart des espèces ne diffère pas de façon significative. La plupart des différences peuvent être interprétées comme des fluctuations annuelles normales. Des changements importants sont identifiés et attribués à des changements de végétation à court terme: augmentation de Columba polleni, Coracopsis vasa, Zoonavena grandidieri, Coracina cinerea dans Nioumbadjou après l'abandon de l'exploitation de la forêt; diminution de Coracina cinerea au Mont Lima Mani Nord après le remplacement de la couche d'arbustes naturelle par des bananiers. De véritables changements de population à long terme sont observés chez Coracopsis nigra (augmentation) et chez Corvus albus (diminution).

Type
Research Article
Copyright
Copyright © Birdlife International 1992

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