High bat mortality at wind energy facilities is a widely cited conservation issue, but the population-level impacts are not understood. In Illinois, the main species affected are migratory tree bats like the Hoary (Lasiurus cinereus) and Eastern Red (Lasiurus borealis).This research used deuterium isotope analysis of hair combined with ecological niche modeling (GARP: Genetic Algorithm for Rule-set Prediction) in a novel way to map the geographic extents of Hoary and Eastern Red bat specimens salvaged at a single central Illinois wind facility from 2008-2010. Hair was chosen after determining that the claw is currently a problematic tissue due to a lack of knowledge about bats' claw growth rates. Hair samples from different sample sites on the body were not significantly different from each other, and there was no significant variation among hair samples from the same body sample site.
The proportions of isotopic extents of both bats' summer ranges revealed that the salvaged specimens came from areas that cover more than 50% of their summer ranges (hence, many populations). When males' and females' isotope extents were overlapped, Hoary bats had less than 50% overlapping of the sexes while Eastern Red bats had over 50%. Relationships among the salvage years and months were also examined. The percentage of overlap among specimen salvage years suggests that these bats utilize their complete range every summer. When each salvage month was examined, there was no evidence of a correlation between month of arrival at the wind facility and their summer geographic extent. This study shows the importance of specimens salvaged from wind facilities for studying both the population-level impacts of wind farm facilities and bat migratory biology.