Wind farm bat fatalities in southern Brazil: temporal patterns and influence of environmental factors

Abstract

Energy demand created by the present model of economic growth has transformed the natural land scape. Changes in megadiverse environments should be accompanied by studies that describe and predict the effects of these changes on ecosystems, underpinning the avoidance or at least the re duction of impacts and species conservation. Wind farm impacts on bats are scarcely known in Brazil. To fulfill this gap on spatiotemporal patterns in bat fatalities in a wind complex in southern Brazil were analysed. Monthly surveys were done around 129 wind towers in search for bat car casses between 2014 and 2018. The number of specimens found per species was analysed in annual sets and also seasonally to understand the influence of land use in the spatial pattern of bat fatalit ies. The activity of aerial insectivore bats was monitored using ultrasound detectors and modelled using Generalized Linear Models (GLM), using meteorological variables as predictors. As a result of 48 months of surveys, 266 carcasses of six insectivorous bat species were recorded. The highest number of fatalities belonged to Tadarida brasiliensis. Fatalities occurred exclusively between Oc tober and May (Austral Spring to Austral Autumn), mainly in towers near the closest urban centre. Most fatalities occurred in the first (69%) and fourth (17%) years of operation; fatalities were pos itively related to wind speed. Eighty-three percent of the bat activity occurred between 15 ◦C and 23 ◦C. To minimize fatalities of synanthropic bat species such as T. brasiliensis, we suggest that wind complexes should be located at least 4 km distant from the urban centres, where those species roost. Moreover, between December and March, when most species from subtropical and temper ate South America reproduce, wind towers located closer to known roosts should shut down on warmer nights, when bats are more active.