Hundreds of thousands of bats are killed annually as they are struck by the huge blades of industrial scale wind turbines. This is something that recent studies by Kristin A. Jonasson, an independent physiological ecologist, help to clarify. For example, she posits that the shiny reflective surfaces of wind turbine blades might lure bats, resulting in deadly collisions. The study focused on two species particularly affected by this phenomenon: the hoary bat (Lasiurus cinereus) and the silver-haired bat (Lasionycteris noctivagans).
Researchers from University of Colorado Colorado Springs, National Renewable Energy Laboratory and U.S. Forestry Service collaborated on the study. Orientation preferences to these experimental Y-maze apparatus were specifically for these two bat species to be analyzed. The height of the Y-maze was 2.35 m tall. It provided a safe and controlled environment to experiment with how bats responded to reflective surfaces of different colors and patterns.
Experimental Setup and Findings
Each study included 396 bats—242 hoary bats and 154 silver-haired bats. Researchers created an experimental paradigm with a twist. At one end of the Y-maze, they installed a long white section of an actual wind turbine blade, brightly lit with simulated moonlight. On one end, they installed a very shiny white blade. This design was meant to figure out how the bats would respond to different levels of reflectance in their surroundings.
The results were striking. Nearly 75 percent of the hoary bats selected the white turbine blade. They chose it instead of the black blade when presented with a choice. In the same way, almost all of the silver-haired bats preferred the white blade to the black. This unexpected discovery yielded surprising results, showing that these species exhibit a strong preference for reflective surfaces. This indicates that they are probably drawn to the blades due to the light they reflect.
“Our work identifies a link between a sensory pollutant—reflective turbine surfaces—and a risky behavior: approaching these surfaces,” – Kristin Jonasson et al.
In situations where exit was open, almost 75% of the hoary bats eventually headed towards the rotating white turbine blade. Nearly every silver-haired bat took the same route. These results should lead us to major concerns that current wind turbine designs are unintentionally advantageous for bats’ fatal encounters.
Implications for Bat Conservation
Bat Conservation International reports that wind turbines are among the leading causes of bat deaths in both North America and Europe. Tens of thousands of bats die by colliding with wind turbine blades annually. To save them, we need to know what’s drawing these bats to wind turbines. Jonasson’s study is an important step toward addressing these risks and finding safer alternatives.
As renewable energy sources, including wind power, continue to grow, figuring out how to minimize their impact on local wildlife must remain a high priority. The study’s insights highlight a need for further research into turbine designs that minimize reflective surfaces and consequently reduce bat fatalities.
Future Research Directions
These are obviously crucial immediate ramifications for science-based conservation efforts, but the implications of this research go much wider. Researchers are now focusing on a wide array of design changes that might reduce the turbine’s visual appeal to bats. Potential changes could be using materials that are less reflective, or new technologies that change the way turbine blades reflect light.
Additional research would build on Jonasson’s groundwork by researching more bat species and their reactions to wind turbine infrastructure. Scientists are broadening the focus of their studies. Their goal is to figure out how different environmental variables influence bat activity patterns near wind energy infrastructure.