Avian biodiversity losses from grazing of high Andean páramo

Abstract

Páramos are high-elevation grassland-dominated ecosystems of the northern Andes that harbour large numbers of small-ranged and endemic species and provide important ecosystem services. Though páramos are increasingly managed with a conservation focus, they remain ecologically threatened, in part due to overgrazing. Here, we assess the impacts of grazing on bird communities using data collected from three páramo complexes in the Eastern Andes of Colombia. We (1) assess how densities of shrubs and frailejones—a keystone group of plants in the páramo—are impacted by grazing, (2) determine the influence of these vegetation features on bird occupancy, and (3) examine how bird species richness and community composition are impacted by páramo grazing. We find that grazing status strongly influences the vegetation characteristics of the páramo, resulting in large reductions in the abundance of shrubs and frailejones. These vegetation changes have significant impacts on páramo bird communities, with reduced shrub abundance resulting in lower occupancy for most species (4 out of 48). As a consequence, grazed páramo communities contain fewer bird species and vary in composition relative to those of natural páramo. However, the magnitudes of these differences are modest and it is possible that low-intensity grazing remains compatible with conservation management. We suggest that it is important to consider how páramo conservation may interact with management of adjacent montane forests and the potential for leakage effects resulting in increased deforestation outside of protected areas.