Choi, D., Wittig, T. W., and Kluever, B. M. 2020. An evaluation of bird and bat mortality at wind turbines in the Northeastern United States. PLOS ONE. Accepted with Revisions April 2020
ABSTRACT. Wind energy offers substantial environmental benefits, but wind facilities can negatively impact wildlife, including birds and bats. Researchers and managers have made major efforts to chronicle bird and bat mortality associated with wind facilities, but few studies have examined the patterns and underlying mechanisms of spatial patterns of fatalities at wind facilities. Understanding the horizontal fall distance between a carcass and the nearest turbine pole is important in designing effective search protocols and estimating total mortality. We explored patterns in taxonomic composition and fall distance of bird and bat carcasses at wind facilities in the Northeastern United States using publicly available data and data submitted to the US Fish and Wildlife Service under scientific collecting and special purpose utility permits for collection and study of migratory birds. Forty-four wind facilities reported 2,039 bird fatalities spanning 128 species and 22 facilities reported 418 bat fatalities spanning five species. Relative to long-distance migratory birds, short-distance migrants were found farther from turbines. Body mass of birds and bats positively influenced fall distance. Turbine size positively influenced fall distance of birds and bats when analyzed collectively and of birds when analyzed separately from bats. This suggests that as turbines increase in size, a greater search radius will be necessary to detect carcasses. Bird and bat fall distance distributions were notably multimodal, but only birds exhibited a high peak near turbine bases, a novel finding we attribute to collisions with turbine poles in addition to blades. This phenomenon varied across bird species, with potential implications for the accuracy of mortality estimates. Although pole collisions for birds is intuitive, this phenomenon has not been formally recognized. This finding may warrant an updated view of turbines as a collision threat to birds because they are a tall structure, and not strictly as a function of their motion.
BACKGROUND. This project began as an internship for the U.S. Fish and Wildlife Service during the summer of 2018. Based out of the USFWS Northeast Regional Office in Hadley, MA, I worked for the Permits Branch of the Migratory Birds Division. I completed this work as part of the USFWS Directorate Resource Assistant Fellows Program.
By compiling 10 years of data collected by the Northeast USFWS, I formed a picture of bird and bat collisions with wind turbines and made recommendations for future management decisions and research direction. My work involved three components:
Synthesizing current knowledge concerning wind-wildlife interactions, focusing on birds and bats
Analyzing data to find trends in bird and bat mortality and summarizing results in a technical report
Exploring dynamics of mortality estimation using the Evidence of Absence software by the US Geological Survey
Voluntarily, I continued this project, working toward a publication, after the 2018 internship.