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Mercury (Hg) is a highly toxic metal that has detrimental effects on wildlife. We surveyed Hg concentrations in 10 species of bats collected at wind farms in the central United States and found contamination in all species. Mercury concentration in fur was highly variable both within and between species (range: 1.08-10.52 µg/g). Despite the distance between sites (up to 1200 km), only 2 of the 5 species sampled at multiple locations had fur Hg concentrations that differed between sites. Mercury concentrations observed in the present study all fell within the previously reported ranges for bats collected from the northeastern United States and Canada, although many of the bats we sampled had lower maximum Hg concentrations. Juvenile bats had lower concentrations of Hg in fur compared with adult bats, and we found no significant effect of sex on Hg concentrations in fur. For a subset of 2 species, we also measured Hg concentration in muscle tissue; concentrations were much higher in fur than in muscle, and Hg concentrations in the 2 tissue types were weakly correlated. Abundant wind farms and ongoing postconstruction fatality surveys offer an underutilized opportunity to obtain tissue samples that can be used to assess Hg contamination in bats. Environ Toxicol Chem 2018;37:160-165. © 2018 SETAC [ABSTRACT FROM AUTHOR]

A better understanding of the ultimate mechanisms driving bat fatalities at wind turbines (i.e., the reason why bats are coming in close proximity to wind turbines) could inform more effective impact reduction strategies. One hypothesis is that bats come into close proximity to turbines due to existing resources (e.g., roosting sites) in the immediate area. Thus, if resource hotspots for bats could be identified in areas proposed for wind energy development, then fatalities could be reduced by siting turbines away from such hotspots. To explore this, we conducted a resource mapping exercise at a 48 km2 wind energy facility in north-central Texas. We mapped known resources (such as water sources, roosting sites, foraging sites, and commuting routes) for the 6 bat species present and compared resource availability with observed fatalities and acoustic activity. Although resource mapping identified concentrations of known resources for all species, it did not predict bat activity or fatalities. For example, Lasiurus cinereus and Lasiurus borealis comprised >90% of the fatalities, yet we found no positive relationship between resource availability and fatalities or acoustic activity for either species. Furthermore, up to 33% of these fatalities occurred at turbines without known resources within 200 m of the turbines, demonstrating that the fine-scale distribution of resources may not effectively inform turbine siting for these two migratory species. The challenge, therefore, remains to determine why bats during the migratory season are coming in close proximity with wind turbines. [ABSTRACT FROM AUTHOR]