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Decline in capture rates of birds in the High Andes of Ecuador suggests broad-scale anthropogenic impacts to protected areas

Abstract:

There is a long history of using birds as indicators of pervasive environmental threats. In the High Andes, birds face potential threats from global climate change, and from the impacts of land use changes associated with logging, grazing, fire, and agricultural expansion. We use an 11-yr constant effort, avian mist-netting dataset from 2 protected areas in the High Andes of Azuay province, Ecuador, to explore how environmental change is affecting resident bird species in high elevation habitats. We estimated a statistically significant mean decrease of 2.8% in capture rate across years for the full species assemblage and across all habitats. Species-specific capture rates across habitats declined for 29 of the 38 species that met our inclusion criteria. When species were grouped by diet, body size, primary habitat occupied, or habitat breadth, capture rates did not change differently among ecological groups of birds. Although we cannot identify the mechanisms behind the decline, the broad nature of the decline suggests that human-induced environmental changes, including warming, altered rainfall patterns, and intensification of land-use, could be acting in combination, resulting in a decline in the populations of many bird species in the region's protected areas. This study highlights how events occurring outside of protected areas may affect resident bird species in these high elevation habitats.