A statistical approach to white-nose syndrome surveillance monitoring using acoustic data

Abstract

Traditional pathogen surveillance methods for white-nose syndrome (WNS), the most serious threat to hibernating North American bats, focus on fungal presence where large congregations of hibernating bats occur. However, in the western USA, WNS-susceptible bat species rarely assemble in large numbers and known winter roosts are uncommon features. WNS increases arousal frequency and activity of infected bats during hibernation. Our objective was to explore the effectiveness of acoustic monitoring as a surveillance tool for WNS. We propose a non-invasive approach to model pre-WNS baseline activity rates for comparison with future acoustic data after WNS is suspected to occur. We investigated relationships among bat activity, ambient temperatures, and season prior to presence of WNS across forested sites of Montana, USA where WNS was not known to occur. We used acoustic monitors to collect bat activity and ambient temperature data year-round on 41 sites, 2011–2019. We detected a diverse bat community across managed (n = 4) and unmanaged (n = 37) forest sites and recorded over 5.37 million passes from bats, including 13 identified species. Bats were active year-round, but positive associations between average of the nightly temperatures by month and bat activity were strongest in spring and fall. From these data, we developed site-specific prediction models for bat activity to account for seasonal and annual temperature variation prior to known occurrence of WNS. These prediction models can be used to monitor changes in bat activity that may signal potential presence of WNS, such as greater than expected activity in winter, or less than expected activity during summer. We propose this model-based method for future monitoring efforts that could be used to trigger targeted sampling of individual bats or hibernacula for WNS, in areas where traditional disease surveillance approaches are logistically difficult to implement or because of human-wildlife transmission concerns from COVID-19.

Climatic factors and host species composition at hibernation sites drive the incidence of bat fungal disease

“…Furthermore, our study suggests that climate change will cause a remarkable shift in the areas in which WND may be manifested, likely leading to new populations being affected by the disease with yet unknown consequences. This prediction demonstrates the need for broad disease surveillance, preferably by using a monitoring method with minimal disturbance for the bats, as suggested previously (Barlow et al 2015, Martínková et al 2019, Hicks et al 2020, Fritze et al 2021b).…”

Applications and advances in acoustic monitoring for infectious disease epidemiology

“…In a laboratory context there are also examples of acoustic data used to understand mating behaviour of mosquito vectors [14]. Otherwise, existing applications almost exclusively relate to the study of wildlife disease ecologyprimarily white-nose syndrome in bats, using ecoacoustic data to survey hibernation sites [15,16], monitor seasonal disease-related behavioural change [17], and assess the implications of climate change on disease progression [18]. There are also a few examples of acoustic monitoring of amphibian disease, discussed in relation to chytridiomycosis [19] and investigating changes in call patterns of infected frogs [20].…”

Could White-Nose Syndrome Manifest Differently in Myotis Lucifugus in Western Versus Eastern Regions of North America? A Review of Factors

“…Data from stationary acoustic detectors in the Pacific Northwest during 2003–2018 (Rodhouse et al 2019) did not detect a decline in M. lucifugus , although little sampling occurred within Pd -positive areas, and the effects of WNS in the 2 yr after initial detection were probably limited. Hicks et al (2020) proposed developing site-specific models of predicted activity from pre-WNS acoustic data that could be used to monitor for increases in winter activity or decreases in summer activity associated with WNS. Although increases in winter activity of M. lucifugus may suggest WNS is present, acoustic monitoring in summer cannot distinguish whether declines in activity would be due to WNS or to other factors such as loss of roosts, foraging habitat, or both.…”