We compared species richness and abundance of birds between five patches under selective Alnus exploitation and five patches that have not been harvested for at least 10 years prior to our study, during the early dry season (April-July 2001), in Cotapata National Park. Using "point counts" we recorded birds and their distribution in two (<1.5 m and >1.5 m) forest layers. Simultaneously we evaluated the floristic structure (size [dbh] distribution, basal area, tree density, tree height, and vegetation cover) and composition (diversity) on three transects placed within each Alnus patch. Both bird diversity and vegetation cover were significantly higher in not presently used patches but only for the higher layer of the forest, whereas plant diversity was higher in presently used patches. Lack of differences between the two types of Alnus patches in any of the vegetation parameters measured in the lower layer was coupled with an indistinct avifauna. Small changes in habitat characteristics following a perturbation like selective logging have the potential to affect richness and abundance of birds, at least within the habitats directly affected by the perturbation.
Nota bibliográficaFunding Information:
This research was funded by the Wildlife Conservation Society and received additional funding from Instituto de Ecología (Universidad Mayor de San Andrés) to MV. Colección Boliviana de Fauna provided access to tape recordings of birds. Emilia García helped with plant identification and commented on a preliminary version of this manuscript. Many thanks to Jon Fjeldsa, Peter Feinsinger, Kazuya Naoki, Susan Davis, and two anonymous reviewers for suggestions to improve this manuscript. Stephen Taranto helped us with a final revision of English. Pedro Salazar provided invaluable help in the field.