The results of the work presented in this thesis represent a first step in understanding the effects of large industrial wind turbines on bats as a group and the hoary bat (Lasiurus cinereus) specifically. Over the past five years it has become clear that wind turbine-associated mortality of bats occurs in some locations and that bats in the genus Lasiurus comprise the bulk of these deaths. Because surveys for bats tend to occur sporadically and to focus on specific species and/or locations, detailed knowledge of bat assemblages is not available for many areas. Lacking this type of information, our ability to place observed mortality in context has been hampered. Turbine-related bat mortality at the Foote Creek Rim Wind Power Facility, located in south-central Wyoming, has been composed chiefly of hoary bats since the facility’s inception in 1999. Because successful mitigation strategies must rely on knowledge about species of interest, this study was initiated in 2000. The main goals of the study were to assess the bat community proximate to the Foote Creek Rim Wind Power Facility, compare those data to the proportional mortality of bats at the facility, and to quantify roosting habitat for the hoary bat.
This thesis is organized into four chapters. Chapter 1 provides an overview of the natural history of the hoary bat. In Chapter 2, I present results of surveys designed to assess the relative abundance of different species of bats in the local area, and how the bat community compares to the relative abundance of species found during searches for dead bats at the wind farm. Chapter 3 summarizes roosting habitat preferences for the hoary bat, and Chapter 4 summarizes the current state of knowledge about bat mortality at wind turbines and explores potential reasons that certain species appear to be more susceptible to wind turbine mortality than other species. Appendix 1 at the end of Chapter 4 provides a general guide to designing studies of bat communities with an eye toward reliability of results and discussion of the limitations and biases associated with survey methods for bats.