Sporadic reports of bat mortality due to collisions with man-made objects exist in the literature. Van Gelder (1956) reported that five red bats (Lasiurus borealis) were killed after colliding with a television tower in Kansas, and Crawford and Baker (1981) reported that over a 25-year period, 54 bats from seven species were killed at a television tower in Florida. Additionally, Saunders (1930) reported that five bats, representing three species, were killed after colliding with a lighthouse at Long Point, Ontario. Bat collisions with wind turbines used to produce electricity also have been noted. At California windplants, Howell and DiDonato (1991) reported finding one dead red bat during a 12-month period, and Orloff and Flannery (1992) reported finding two bat carcasses during a 24-month period.
Recent technological advances have reduced costs associated with wind-power production to a level that is competitive with more traditional methods of producing electricity (Nelson and Curry, 1995). As a result, utility companies increasingly use wind power as an alternative source of energy (Hanson et. al., 1992). While wind power is generally viewed as an environmentally friendly source of energy, the number of avian mortalities at existing windplants has caused concern among many state, federal, and non-profit organizations.
To date, most studies were designed to assess the biological impacts on windplants on bird species. In comparison to birds, bat collisions with wind turbines appear to be infrequent and therefore have receive little attention by natural resource agencies or the scientific community. While conducting a study to asses the impacts of a windplant on birds in southwestern Minnesota, we found several dead bats. The purpose of this paper is to document the species composition and timing of bat mortality associated with the Minnesota windplant during 1994 and 1995. We also review some current theories regarding bat collisions with man-made structures and speculate on the possible causes of bat mortality at windplants.