Sensitivity of tropical montane birds to anthropogenic disturbance and management strategies for their conservation in agricultural landscapes.

Tropical montane bird communities are hypothesized to be highly sensitive to anthropogenic disturbance, because species are adapted to a narrow range of environmental conditions and display high rates of endemism. Here, we assess avian sensitivity at regional and continental scales for a global epicenter of montane biodiversity, the tropical Andes. Using data from: (1) an intensive field study of cloud forest bird communities across seven landscapes undergoing agricultural conversion in northern Peru (1800 - 3100m) and (2) a pan-Andean synthesis of forest bird sensitivity, we develop management strategies for maintaining avian biodiversity within tropical countrysides and examine how environmental specialization predicts species-specific sensitivity to disturbance. In Peru species richness declined 20 - 93% compared to forests across our agricultural land use gradient and was accompanied by high levels of species turnover. Fragments of mature forest acted as reservoirs for forest bird diversity, especially when large or surrounded by mixed successional vegetation. Within high intensity agricultural plots, an addition of 10 silvopasture trees or 10% more fencerows per hectare increased species richness by 18 - 20%. Trophic groups most sensitive to disturbance were insectivores and frugivores, with 40-70% of species showing abundance declines in early successional vegetation and silvopasture. These results were supported by our synthesis of N = 816 montane bird species studied across the Andes. At least a quarter declined due to some form of disturbance, with the proportion rising to 60% in agricultural landscapes. Species with narrow elevational range limits, smaller global range sizes, insectivorous/carnivorous diets, and specialized trophic niches were most sensitive. We recommend sparing forest fragments, especially larger ones, while increasing connectivity through the maintenance of early successional vegetation and silvopastoral trees that also increase avian diversity within pastures. We provide lists of species-specific sensitivities to anthropogenic disturbance to inform conservation status assessments of Andean birds. This article is protected by copyright. All rights reserved.