Under federal environmental law, bat species are not afforded legal protection unless covered under the federal Endangered Species Act (ESA). Under the ESA it is unlawful to take (e.g., harm, harass or kill) any federally endangered or threatened species. Examples of bat species that are covered by the ESA are the Indiana bat (endangered) and the Northern long-eared bat (threatened). Under some circumstances, the United States Fish & Wildlife Service may authorize the take of such species by issuing an Incidental Take permit.
Although other bat species that are not listed under the ESA are not afforded such legal protection, wind turbine risk to bats continues to be a focus of research and efforts to minimize such risk. In April, the Department of Energy announced funding of more than $1.75 million to examine technologies to reduce the potential impacts of wind turbines to bats. The technologies to be studied include altered textures of wind turbine coating materials that may deter bats from approaching the structures, and ultrasonic deterrents.
In September, the American Wind Energy Association (AWEA) announced the support of some of its members to voluntarily curtail wind turbines in low wind speed conditions during fall bat migration periods (generally from mid-July through mid-October). AWEA explained that the voluntary measures were developed by its Siting and Environmental Compliance Committee and are meant to be applied on a site-by-site basis to those sites where commercially feasible and where potential impacts warrant the measures. Since turbine curtailment reduces the amount of energy produced, lenders to wind projects should be aware of this possible voluntary limitation to production that may be implemented by some projects.