Bird and bat mortality at wind farms in South America: Lessons from monitoring and mitigation practices in Chile

Wind energy can help mitigate global CO₂ emissions; however, it also has adverse effects on biodiversity, particularly through collision-related mortality among flying vertebrates. While these impacts have been extensively studied in North America and Europe, information from South America remain limited. In this study, we assessed bird and bat mortality, along with monitoring and mitigation practices at wind farms in Chile, one of the leading countries in wind energy development in South America. We analyzed 15 years of post-operational monitoring data from 47 wind facilities and examined the drivers of wildlife mortality and evaluate the methods used to monitor, estimate, and mitigate these impacts. We documented a total of 1218 bird fatalities representing 80 different species, and 1250 bats fatalities from 6 species. The only threatened species recorded was the Andean condor (Vultur gryphus), with nine casualties across three wind farms, all located in the north-central Chile. While bird collisions showed no clear seasonal pattern, bat mortality peaked during spring and autumn. Mortality rates were influenced by a range of factors, including environmental, biotic, geographic, and turbine-related characteristics. Our study revealed that monitoring strategies are often inconsistently reported and lack standardization. Carcass removal trials, essential for correcting detection and persistence biases, are rarely conducted. Only 56 % of the wind farms implemented mitigation measures, with passive measures more commonly adopted than active ones. These findings highlight the need to standardize monitoring protocols and apply appropriate bias correction methods in mortality estimates at the wind farm scale. These improvements are essential for drawing reliable conclusions about wildlife impacts and for designing effective mitigation strategies at regional and national levels.