The potential introduction of SARS-CoV-2, the virus responsible for the COVID-19 pandemic, into North American bat populations is of interest to wildlife managers due to recent declines of several species. Populations of little brown bats (Myotis lucifugus) have collapsed due to white-nose syndrome (WNS), a disease caused by the introduction and spread of the fungal pathogen Pseudogymnoascus destructans (Pd). Throughout much of the United States and southern Canada, large colonies of the species routinely established diurnal roosts in anthropogenic structures creating the potential for direct human contact and cross-species disease transmission. Given recent declines and the potential for further disease impacts, we collected oral swabs from eight little brown bat colonies for RT-qPCR analysis to describe the presence and prevalence of SARS-CoV-2. We visited colonies in Maryland (n = 1), New Hampshire (n = 1), New Jersey (n = 2), New York (n = 1), Rhode Island (n = 2), and Virginia (n = 1) during May-August, 2022. We have analyzed samples from 235 individuals and all have tested negative for SARS-CoV-2. Our results indicate that little brown bats are either negative for SARS-CoV-2 or that it persists in undetectable levels in populations of the Mid-Atlantic and Northeast in the summer months. Nonetheless, future work addressing other seasons or using serologic approaches may still be warranted to conclusively determine disease status.

We experimentally challenged wild Mexican free-tailed bats (TABR) with SARS-CoV-2 to determine the susceptibility, reservoir potential, and population impacts of infection in this species. Of nine bats oronasally inoculated with SARS-CoV-2, five became infected and orally excreted moderate amounts of virus for up to 18 days post inoculation. These five subjects all seroconverted and cleared the virus before the end of the study with no obvious clinical signs of disease. We additionally found no evidence of viral transmission to uninoculated subjects. These results indicate that while TABR are susceptible to SARS-CoV-2 infection, infection of wild populations of TABR would not likely cause mortality.

This work is part of a study investigating the movement of microcystin from aquatic to terrestrial ecosystems via trophic transfer. Little brown bats (Myotis lucifugus), feeding opportunistically on aquatic insects including Hexagenia mayflies, were collected from a maternity roost near Little Traverse Lake (Leelanau County, Michigan, USA). Bats and fecal samples were collected for dietary analysis, quantification of microcystin in livers and feces, and histopathological evaluation of the liver. Liver was collected in RNAlater and stored frozen. Livers from three bats with the highest microcystin levels by ELISA were thawed, washed with PBS, fixed in 10% neutral buffered formalin, processed routinely for histopathology, and assessed by light microscopy. Microscopic lesions included centrilobular congestion, periportal to midzonal hepatocellular vacuolation, and low numbers of portal inflammatory cells. These changes are non-specific; no evidence of acute microcystin toxicosis was present. Results suggest that despite the detection of microcystin in bat feces from the site, there is no evidence of acute clinical toxicity in the bats collected.

White-nose syndrome (WNS), a fungal disease that has caused catastrophic population declines of bats in eastern North America, is rapidly spreading across the continent and now threatens previously unexposed bat species in western North America. The causal agent of WNS, Pseudogymnoascus destructans, can infect many species of hibernating bats, but susceptibility to WNS varies by host species. Predicting which western bat species will be most susceptible to WNS would be of great value for establishing conservation priorities. We previously reported that certain traits of the skin microbiome of bat species in eastern North America were strongly associated with tolerance to WNS. Using these traits, we developed a model to predict WNS susceptibility of 13 species of western North American bats. Based on the model, only two bat species, Myotis velifer and Eptesicus fuscus, were predicted to be WNS-tolerant. If accurate, a greater proportion of western bat species will be susceptible to the disease compared to eastern bat species, indicating that WNS may pose a significant conservation threat in western North America.

North American bats have experienced catastrophic population declines from white-nose syndrome (WNS), a fungal disease caused by Pseudogymnoascus destructans (Pd). Although Pd can infect many hibernating bat species, population-level impacts of WNS vary by host species. Microbial skin assemblages, including the fungal component (mycobiome), can influence host resistance to infectious diseases; however, little is known about the influence the skin mycobiome of bats may have on susceptibility to WNS. We sampled ten bat species in the eastern United States that are known to be either susceptible, tolerant, or resistant to WNS by swabbing their wing skin. We then cultured fungi from the swabs, isolated morphologically distinct colonies of fungi, and identified the fungi through DNA sequencing. Using this culture-based approach, we compared skin mycobiome characteristics. The mycobiomes of WNS-susceptible bat species had significantly lower alpha diversity and abundance compared to WNS-tolerant species. Overall mycobiome structure did not vary based on WNS-susceptibility, but several yeast species were differentially abundant on WNS-tolerant bat species. Multi-locus phylogenies and scanning electron microscopy suggest that some yeasts likely represent novel taxa which may be adapted to colonizing bat skin. Further exploration of interactions between Pd and components of the mycobiome may prove useful for predicting susceptibility of bat populations and for developing effective mitigation strategies for WNS.

False positive occupancy analysis predictions with model uncertainty based on summertime data provided to support the three bat species status assessment (SSA) for Myotis lucifigus (MYLU), Myotis septentrionalis (MYSE), and Perimyotis subflavus (PESU). The objectives outlined by the Fish and Wildlife Service’s SSA team were to estimate summertime distributions across the entire species range. Statistical analysis included five types of response data requested from the North American Bat Monitoring Program database (NABat): automatically identified stationary acoustic calls, manually vetted stationary acoustic calls, automatically identified mobile acoustic calls, manually vetted mobile acoustic calls, and capture records. Statistical analysis was for the summertime distribution modeling, data collected between June 1 and Sept 1 during 2010 until 2019 were only included.

Through the North American Bat Monitoring Program, Bat Conservation International and U.S Geological Survey (USGS) provided technical and science support to assistance in U.S. Fish and Wildlife Service Species Status Assessment (“SSA”) for the northern long-eared bat (Myotis septentrionalis), little brown bat (Myotis lucifugus), and tri-colored bat (Perimyotis subflavus). USGS facilitated the SSA data call providing data archival for repeatable and transparent analyses, provided statistical support to assess the historical, current, an future population status for each of the three species, and developed a demographic projection tool to evaluate future viability of each species under multiple threat scenarios. We assessed population trends from count surveys of wintering colonies at hibernacula for these three bat species. Winter colony counts were downloaded from the database of the North American Bat Monitoring Program (U.S. Geological Survey North American Bat Monitoring Program. Accessed 2020-12-01. NABat Request Number 12. Database Version v5.4.0).

The endangered Indiana bat (Myotis sodalis) has declined dramatically and continuing threats have made it necessary to understand population dynamics and life history throughout the year. Specifically, demographic information (e.g., population size, reproductive success, survival) from the summer range where females raise their young in maternity colonies is difficult to estimate precisely using traditional techniques (such as emergence counts). Further, the familial makeup of maternity colonies is unknown. Genetic mark-recapture methods are increasingly being used to estimate demographic parameters in species where traditional techniques are problematic and can also provide insight into relatedness among individuals. Therefore, our objectives were to: 1) use genetic mark-recapture to provide estimates of survival, detection probability and population size of Indiana bats at a maternity roost in Indianapolis, IN, 2) compare population size estimates using genetic mark-recapture with emergence counts collected at the same roost tree, and 3) document levels of relatedness among individuals. In the summer of 2008, we collected fecal pellets and conducted emergence counts at a prominent roost tree during three time periods each lasting seven or eight days. We genotyped fecal DNA using five highly polymorphic microsatellite loci to identify individuals and used a robust design mark-recapture approach to estimate detection and survival probabilities as well as population size at the roost. Emergence count estimates ranged from 100 - 215, whereas genetic mark-recapture estimates were higher ranging from 122 – 266 and more precise (with smaller confidence intervals). Apparent survival was 0.994 (SE=0.04) between sampling periods suggesting that few bats died or permanently emigrated during the course of the study. Relatedness estimates, r, between all pairs of individuals averaged 0.055 ranging from 0 – 0.779 indicating that most individuals were not closely related. We demonstrate here the promise of using fecal DNA to estimate demographic information for Indiana bats and potentially other bat species.

This work is part of an experimental trial investigating the effects of microclimate conditions of temperature and humidity on a fungal pathogen, Pseudogymnoascus destructans (Pd), that causes white-nose syndrome (WNS) disease in hibernating bats. As part of the trial, tri-colored bats (Perimyotis subflavus) were exposed to Pseudogymnoascus destructans (Pd) and allowed to hibernate in chambers with a variety of temperature and humidity conditions. Bats were euthanized after 83 days. A portion of the wing was rolled around dental wax dowels, fixed in 10% neutral buffered formalin, processed and stained with periodic acid-Schiff, and assessed by light microscopy for evidence of fungal infection. Three types of cutaneous infection were described histologically, including characteristic WNS cupping erosions, neutrophilic pustules with fungal hyphae, and fungal hyphae in the stratum corneum with dermal necrosis. Bats with any of these three conditions were scored as WNS-positive by histology. Only 11% (10/95) of bats scored as positive by histology. Of the 10 bats scored as positive, 3 bats had cupping erosions containing fungal hyphae and 7 bats had either neutrophilic pustules containing fungal hyphae, dermal necrosis associated with intra-epidermal fungal hyphae, or both. Overall, lack of infection and disease outcomes in this experiment limited our ability to make robust conclusions about the influence of microclimates on the development of WNS in bats.

This work is part of an experimental trial investigating the effects of microclimate conditions of temperature and humidity on a fungal pathogen, Pseudogymnoascus destructans (Pd), that causes white-nose syndrome (WNS) disease in hibernating bats. As part of the trial, tri-colored bats (Perimyotis subflavus) were exposed to Pseudogymnoascus destructans (Pd) and allowed to hibernate in chambers with a variety of temperature and humidity conditions. Bats were euthanized after 83 days. A portion of the wing was rolled around dental wax dowels, fixed in 10% neutral buffered formalin, processed and stained with periodic acid-Schiff, and assessed by light microscopy for evidence of fungal infection. Three types of cutaneous infection were described histologically, including characteristic WNS cupping erosions, neutrophilic pustules with fungal hyphae, and fungal hyphae in the stratum corneum with dermal necrosis. Bats with any of these three conditions were scored as WNS-positive by histology. Only 11% (10/95) of bats scored as positive by histology. Of the 10 bats scored as positive, 3 bats had cupping erosions containing fungal hyphae and 7 bats had either neutrophilic pustules containing fungal hyphae, dermal necrosis associated with intra-epidermal fungal hyphae, or both. Overall, lack of infection and disease outcomes in this experiment limited our ability to make robust conclusions about the influence of microclimates on the development of WNS in bats.