White-nose syndrome (WNS) is a disease caused by the fungus Pseudogymnoascus destructans which has resulted in the deaths of millions of bats across eastern North America. To date, hibernacula counts have been the predominant means of tracking the spread and impact of this disease on bat populations. However, an understanding of the impacts of WNS on demographic parameters outside the winter season is critical to conservation and recovery of bat populations impacted by this disease. We used long-term monitoring data to examine WNS-related impacts to summer populations in West Virginia, where WNS has been documented since 2009. Using capture data from 290 mist-net sites surveyed from 2003–2019 on the Monongahela National Forest, we estimated temporal patterns in presence and relative abundance for each bat species. For species that exhibited a population-level response to WNS, we investigated post-WNS changes in adult female reproductive state and body mass. Myotis lucifugus (little brown bat), M. septentrionalis (northern long-eared bat), and Perimyotis subflavus (tri-colored bat) all showed significant decreases in presence and relative abundance during and following the introduction of WNS, while Eptesicus fuscus (big brown bat) and Lasiurus borealis (eastern red bat) responded positively during the WNS invasion. Probability of being reproductively active was not significantly different for any species, though a shift to earlier reproduction was estimated for E. fuscus and M. septentrionalis. For some species, body mass appeared to be influenced by the WNS invasion, but the response differed by species and reproductive state. Results suggest that continued long-term monitoring studies, additional research into impacts of this disease on the fitness of WNS survivors, and a focus on providing optimal non-wintering habitat may be valuable strategies for assessing and promoting recovery of WNS-affected bat populations.

Data collection: From 2003–2019, bat mist-net surveys were conducted across 290 sites on the Monongahela National Forest. Nets were operated for 2 nights/year at each site. When inclement weather prevented completion of a full survey at a given site, additional surveys were conducted until 2 full survey nights were completed. Individual bat data from partial survey nights are included in the “Reproductive State” and “Body Mass” data sheets, but partial survey nights are excluded from the “Count” data sheet so that sampling effort is consistent across sites. At least 20 sites were surveyed each year (range = 20–58 sites/year, mean = 37.9), with individual sites surveyed from 1–10 years over the 17-year study period (mean = 2.1 years/site). Of the 290 survey sites, 250 were surveyed pre-WNS (2003–2008) and 135 were surveyed from 2009–2019; 96 sites (33%) were surveyed during both time periods, with 58 of those sites having at least 4 years of survey data. See the publication "Long-term changes in occurrence, relative abundance, and reproductive fitness of bat species in relation to arrival of White-nose Syndrome in West Virginia, USA" for additional sampling information.

Data processing: For the “Count” sheet, we computed the number of bats captured per site for each species during each survey year. The “Reproductive State” and “Body Mass” sheets contain the raw observational data collected in the field.

ReadMe file: MNF bat data_readme.txt