White‐nose Syndrome and Environmental Correlates to Landscape‐Scale Bat Presence

Abstract

ABSTRACTOver the past 13 years, White‐nose Syndrome (WNS) has caused North American bat population declines and shifted community structure towards species less or unaffected by the disease. Mist‐netting, acoustic surveys, and cave count data have been used to document changes in bat presence and activity through site‐specific, pre‐ and post‐WNS studies. Management and survey guidance often must be applied at a combined landscape and site‐specific scale. Our objective was to explore the relationships among WNS impact, influence of available hibernacula, and environmental factors for the nightly presence of 3 WNS‐affected bats: the Indiana bat (Myotis sodalis), northern long‐eared bat (M. septentrionalis), and big brown bat (Eptesicus fuscus). We used recordings from 10 acoustic monitoring study areas, each with 3 survey locations across the states of Virginia, West Virginia, Ohio and Kentucky to assess changes in nightly bat presence during the summer of 2017. There were significant positive and negative correlates of broad land‐cover categories for presence of all 3 bat species. Our findings also corroborated trends in abundance and distribution patterns found in prior, smaller‐scale studies, supporting the relevance of land cover categories in a large‐scale acoustic monitoring framework. We observed a negative association between WNS impact‐years and nightly northern long‐eared bat presence, but low occurrence and patchy distribution reduced our ability to infer strong relationships. Big brown bat presence showed a significant positive relationship with WNS occurrence on the landscape, providing evidence that big brown bats are maintaining populations after years of exposure. Indiana bats were the least‐documented species, limiting the strength of our conclusions, but we did observe significant temporal patterns in nightly presence, with higher probabilities of presence earlier in the summer. Our results show the potential efficacy of using a WNS impact metric to predict summer bat presence, inform current U.S. Fish and Wildlife Service acoustic monitoring guidelines, and highlight which environmental variables are relevant for large‐scale acoustic monitoring. © 2021 The Wildlife Society. This article has been contributed to by US Government employees and their work is in the public domain in the USA.