Changes in summer bat captures in the Black Hills, South Dakota, after white-nose syndrome invasion

Hibernating bat populations in North America are declining due to white-nose syndrome (WNS), a fungal disease that has recently spread into the northern Great Plains. First confirmed in South Dakota’s Black Hills in 2018, WNS now threatens regional bat communities. To assess how western bat populations respond to WNS, we analyzed mist-net survey data from 2 phases: invasion (2017 to 2019) and establishment (2022 to 2024), comparing capture rates across species. Four Myotis species declined by ≥95%: Little Brown Myotis (Myotis lucifugus), Fringed Myotis (M. thysanodes), Long-Legged Myotis (M. volans), and the federally endangered Northern Myotis (M. septentrionalis). In contrast, 4 less susceptible species saw capture rates increase by over 200% during the establishment phase. The Hoary Bat (Lasiurus cinereus), which is not susceptible to WNS, showed a more modest increase (64%). These results suggest that WNS impacts in western bat populations mirror eastern post-WNS population trends, and that some western species (M. thysanodes and M. volans) are at high risk of disease-driven extirpation. However, the marked increases in less susceptible species indicate that non-disease drivers may be influencing bat populations in western states, warranting independent study.