Abundance and patterns of rarity of rarity of Polylepis birds in the Cordillera Vilcanota, southern Perú: Implications for habitat management strategies

Abstract

Point count distance sampling surveys were conducted at three sites in the Cordillera Vilcanota to determine whether variation in high-Andean species richness, diversity and abundance was a reflection of Polylepis habitat quantity. Bird community and abundance measures revealed that there was considerably variation in bird species richness, diversity and mean encounter rates between large, medium, and small forest patches. Densities of Polylepis-dependent bird species (including five globally-threatened and eight restricted-range species) were greater in larger forest patches and differed significantly between different patch size categories. Density estimates for matrix-dependent species were higher in smaller Polylepis patches indicating that the matrix exerts an influence on bird species composition and abundance in remnant Polylepis forests, particularly smaller patches. Comparison of lowland forest habitat specialists using three categories of rarity revealed that between 19-22% of all Polylepis-dependent species were intrinsically rare within larger forest patches, and a greater number (34-74%) were rare in smaller forest patches. Population estimates for all species, in particular for all threatened species, were extremely low, numbering ≤ 10 individuals at nine of the ten sites examined. The results suggest that declines in the densities of certain Polylepis birds may be predictable following habitat loss and that these patterns of rarity should govern population recovery goals through appropriate habitat restoration strategies. Such strategies are urgently required and must be designed to prevent further habitat loss, and to increase Polylepis habitat quantity to boost threatened bird populations in the Cordillera Vilcanota. © Birdlife International 2008.