Red aviation lights on wind turbines do not increase bat-turbine collisions

Abstract

Many hypotheses have been proposed to explain why bat–wind turbine collisions occur; however, most of these hypotheses have yet to be tested and with high numbers of bat fatalities reported annually at wind resource facilities globally, there is a real need to understand this phenomenon. In this study, we tested whether aviation lighting influenced the number of bat fatalities at wind turbines. Thus, at a utility-scale wind facility in north-central Texas, we explored whether bat fatalities were higher at wind turbines with red flashing aviation lighting compared with turbines without such lighting. Over a 5-year period, we recorded fatalities at wind turbines as part of a long-term fatality monitoring programme. During standardized searches, we collected 916 bat carcasses representing all six species known to be present at the site. We found that bat fatalities were higher at wind turbines without aviation lighting compared with those with; a pattern that was driven by one species, Lasiurus borealis, and there was no significant difference between fatalities at wind turbines with or without aviation lighting for any other species. Our study demonstrates that wind turbines should continue to be fitted with synchronized, flashing red aviation lights, as this form of lighting does not appear to be one of the potential causes of bat fatalities at wind resource facilities. We therefore support further research that explores possible alternative causes of bat–wind turbine interactions. More specifically, we reiterate that there is still a pressing need to determine the aspects of bat ecology that result in individuals coming into contact with wind turbines.