Hoary Bat ( Lasiurus cinereus ) ecology and conservation through the lens of the full annual cycle

Abstract

The Hoary Bat (Lasiurus cinereus) is the most frequently reported bat killed at North American wind energy facilities, driving the United States and Canada to consider regulatory protections for the species. The Hoary Bat is a widely distributed, long-distance migratory bat, but gaps remain about the species' ecology to inform best practices for conservation and management. We synthesize information on Hoary Bat ecology in the context of the full annual cycle, with specific attention paid to the species' interactions with wind turbines. Hoary bats generally hibernate through winter, especially at lower latitudes and in coastal areas. In spring, hoary bats migrate from winter to summer habitat. Spring is also characterized by pregnancy for females; pups are born in summer. Migration to overwintering sites and mating both occur in late summer and autumn, with adults searching for mating opportunities over large spatial expanses. Late summer and early autumn coincide with a peak in wind turbine fatalities. This seasonality in fatality events provides an opportunity to concentrate conservation efforts to reduce collision risk. While various fatality minimization strategies are under development, curtailment is currently the most effective strategy available. Systematic sampling at wind energy facilities for turbine-related fatalities, acoustic and genetic sampling, and better data sharing offer opportunities to better estimate the species' population status and trends. While questions remain, enough information exists to make informed decisions to reduce the impact of wind turbines on hoary bats as scientists pursue research to better inform future management decisions.