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Durée optimale d'écoute pour la détermination d'indices ponctuels d'abondance dans les paysages ruraux des hauts de la Réunion

Tassin J., Rivière J.N.. 2004. Alauda, 72 (3) : p. 187-191.

IPAs (Ponctual Index of Abundance) are used to study relations between birds and their environment. In order to identify a saturation stage in contacting birds, which corresponds to the optimal IPA, it is necessary to test the relevance of different point count durations (5 min, 10 min, 15 min, 20 min). We tested it in rural landscapes of highlands of Reunion Island. Expressed in their relative abundance value, native birds are not detected any faster than exotic ones, although they can be attracted to the observer. For the 10 commonest species (detected in at least 20 point counts), at least 30% of individual birds are contacted during the first 5 min (> 60% after 10 min, > 80% after 15 min). The abundance of each bird species differs significantly each time we increase the duration of 5 min. Foudia madagascariensis is the most easily detected species. Within the con-text of this study, a duration of 15 min is optimal, as it corresponds to the a saturation stage in contacting birds. (Résumé d'auteur)

Mots-clés : impact sur l'environnement; Écosystème; ornithologie; espèce nouvelle; organisme indigène; dynamique des populations; oiseau; réunion

Thématique : Ecologie animale; Conservation de la nature et ressources foncières; Méthodes de relevé

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