Resumen

HERZOG, Sebastian K.; SORIA AUZA, Rodrigo W.  y  BENNETT HENNESSEY, A.. Ecoregional patterns of richness, endemism and threat of the Bolivian avifauna: priorities for ecoregional planning. Ecología en Bolivia [online]. 2005, vol.40, n.2, pp.27-40. ISSN 1605-2528.

Ecoregions are increasingly accepted as useful geographical units for conservation planning, but to date ecoregional priorities have not been formally evaluated for Bolivia and other highly diverse tropical countries. We propose a new, simple quantitative method in order to assign conservation priority scores to ecoregions using birds as a model taxon. Analyses were based on the distributional data contained in the “Lista Anotada de las Aves de Bolivia” (Hennessey et al. 2003), partially updated with recent data, for 1.396 native Bolivian bird species. Ten ecoregions were ranked according to six parameters of conservation importance, and ranks were summed for each region to obtain an overall score: (1) Species richness, (2) faunal distinctiveness, (3) number of restricted-range species, including all political endemics and near-endemics (n = 77), (4) number of threatened and near-threatened species (n = 69) (parameters 3 and 4 combined contained 117 species referred to as “conservation concern [CC] species”), (5) number of insufficiently protected CC species (n = 71), (6) number of ecoregionally restricted CC species (n = 59). The Yungas ecoregion contained the greatest number of restricted-range and ecoregionally restricted CC species, whereas Amazonia had the highest number of species and of insufficiently protected CC species. The Treeline was the faunally most distinctive ecoregion, and Eastern Bolivia (i.e., the Cerrado and the Pantanal) had the highest number of threatened species. In the overall ranking the Yungas emerged as the top bird conservation priority, followed by Amazonia, inter-andean dry valleys, eastern Bolivia, and the Andean timberline; the Chiquitanía and the Chaco obtained the lowest scores, respectively. When considering the relative contribution of CC species to the total richness in each ecoregion, the Andean timberline emerged as the top priority region. Correlation analyses revealed five significant positive relationships between conservation importance parameters, involving all six parameters, but removing the most redundant parameter from the analysis resulted in virtually the same ranking of ecoregions. The gradient between top and minimum score was steep, with the remaining ecoregions positioned fairly evenly in between, suggesting that the simple method of ranking ecoregions for different conservation parameters is an informative and powerful tool. It is hoped that the method will be applied to other taxonomic groups to obtain a more complete picture of ecoregional conservation priorities in Bolivia and other tropical countries.

Palabras clave : Ecoregion; birds; conservation priorities; Bolivia.

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