Declines in summer bat activity in central New England 4 years following the initial detection of white-nose syndrome

White-nose syndrome (WNS) was first reported in a hibernating bat population in central New York State in February 2006. Since 2006, WNS has been reported from bat hibernacula across much of eastern United States and adjacent Canada and has been associated with a dramatic decline in the populations of hibernating bats in the northeastern U.S. We are only beginning to discover how these declines are manifest in changes in summer bat abundance and activity at local scales. A 3-year (2004–2006) acoustic survey showed that the forested watershed of the Quabbin Reservoir in central Massachusetts supported an abundant and species-rich summer bat community. In 2010, 4-years following the initial occurrence of WNS, a re-survey of the same habitats and sites found a 72% reduction in bat activity on the watershed. This is the identical rate of decline reported from cave hibernacula surveys (73%). This decline in summer activity levels is most likely a consequence of WNS-caused mortality. The impacts of population losses of this magnitude of a once widespread and abundant taxa are unknown but are presumed to be ecologically significant.     

Hibernacula microclimate and declines in overwintering bats during an outbreak of white‐nose syndrome near the northern range limit of infection in North America

We document white‐nose syndrome (WNS), a lethal disease of bats caused by the fungus Pseudogymnoascus destructans (Pd), and hibernacula microclimate in New Brunswick, Canada. Our study area represents a more northern region than is common for hibernacula microclimate investigations, providing insight as to how WNS may impact bats at higher latitudes. To determine the impact of the March 2011 arrival of Pd in New Brunswick and the role of hibernacula microclimate on overwintering bat mortality, we surveyed bat numbers at hibernacula twice a year from 2009 to 2015. We also collected data from iButton temperature loggers deployed at all sites and data from HOBO temperature and humidity loggers at three sites. Bat species found in New Brunswick hibernacula include Myotis lucifugus (Little Brown Bat) and M. septentrionalis (Northern Long‐eared Bat), with small numbers of Perimyotis subflavus (Tricolored Bat). All known hibernacula in the province were Pd‐positive with WNS‐positive bats by winter 2013. A 99% decrease in the overwintering bat population in New Brunswick was observed between 2011 and 2015. We did not observe P. subflavus during surveys 2013–2015 and the species appears to be extirpated from these sites. Bats did not appear to choose hibernacula based on winter temperatures, but dark zone (zone where no light penetrates) winter temperatures did not differ among our study sites. Winter dark zone temperatures were warmer and less variable than entrance or above ground temperatures. We observed visible Pd growth on hibernating bats in New Brunswick during early winter surveys (November), even though hibernacula temperatures were colder than optimum for in vitro Pd growth. This suggests that cold hibernacula temperatures encountered near the apparent northern range limit for Pd do not sufficiently slow fungal growth to prevent the onset of WNS and associated bat mortality over the winter.     

Emergence activity at hibernacula differs among four bat species affected by white‐nose syndrome

Prior to the introduction of white‐nose syndrome (WNS) to North America, temperate bats were thought to remain within hibernacula throughout most of the winter. However, recent research has shown that bats in the southeastern United States emerge regularly from hibernation and are active on the landscape, regardless of their WNS status. The relationship between winter activity and susceptibility to WNS has yet to be explored but warrants attention, as it may enable managers to implement targeted management for WNS‐affected species. We investigated this relationship by implanting 1346 passive integrated transponder (PIT) tags in four species that vary in their susceptibility to WNS. Based on PIT‐tag detections, three species entered hibernation from late October to early November. Bats were active at hibernacula entrances on days when midpoint temperatures ranged from −1.94 to 22.78°C (mean midpoint temperature = 8.70 ± 0.33°C). Eastern small‐footed bats (Myotis leibii), a species with low susceptibility to WNS, were active throughout winter, with a significant decrease in activity in mid‐hibernation (December 16 to February 15). Tricolored bats (Perimyotis subflavus), a species that is highly susceptible to WNS, exhibited an increase in activity beginning in mid‐hibernation and extending through late hibernation (February 16 to March 31). Indiana bats (M. sodalis), a species determined to have a medium–high susceptibility to WNS, remained on the landscape into early hibernation (November 1 to December 15), after which we did not record any again until the latter portion of mid‐hibernation. Finally, gray bats (M. grisescens), another species with low susceptibility to WNS, maintained low but regular levels of activity throughout winter. Given these results, we determined that emergence activity from hibernacula during winter is highly variable among bat species and our data will assist wildlife managers to make informed decisions regarding the timing of implementation of species‐specific conservation actions.     

Risk factors associated with mortality from white-nose syndrome among hibernating bat colonies

White-nose syndrome (WNS) is a disease responsible for unprecedented mortality in hibernating bats. First observed in a New York cave in 2006, mortality associated with WNS rapidly appeared in hibernacula across the northeastern United States. We used yearly presence-absence data on WNS-related mortality among hibernating bat colonies in the Northeast to determine factors influencing its spread. We evaluated hazard models to test hypotheses about the association between the timing of mortality and colony-level covariates, such as distance from the first WNS-affected site, colony size, species diversity, species composition and type of hibernaculum (cave or mine). Distance to origin and colony size had the greatest effects on WNS hazard over the range of observations; the type of hibernaculum and species composition had weaker effects. The distance effect showed a temporal decrease in magnitude, consistent with the pattern of an expanding epizootic. Large, cave-dwelling bat colonies with high proportions of Myotis lucifugus or other species that seek humid microclimates tended to experience early mortality. Our results suggest that the timing of mortality from WNS is largely dependent on colony location, and large colonies tend to be first in an area to experience high mortality associated with WNS.     

White-nose syndrome and wing damage index scores among summer bats in the northeastern United States

White-nose syndrome (WNS) adversely affects millions of bats hibernating in caves of the eastern United States. Beginning in 2009, the US Fish and Wildlife Service supported use of a wing damage index (WDI) scoring system (scale of 0 to 3, or no damage to severe) to assess wing damage of bats captured during summer. Based on bat captures at 459 mist net sites in Pennsylvania, New York, Maryland, Virginia, and New Jersey, USA, we questioned whether WDI scores varied by species group, date, and distance to the closest known affected hibernaculum. We also compared relative health (body mass index [BMI] scores) to WDI scores. Of 3,419 bats (nine species), only four individuals (0.1%; little brown [Myotis lucifugus] and northern bats [Myotis septentrionalis]) were scored as a 3 and 47 (1.4%; big brown [Eptesicus fuscus], little brown, and northern bats) as a 2. All tree bats (eastern red [Lasiurus borealis], hoary [Lasiurus cinereus], and silver-haired bats [Lasionycteris noctivagans]) scored a 0 or 1, suggesting that these species were not affected by WNS. The average WDI score decreased as summer progressed, although trends were weak. Average WDI score and number of bats with class 2 and 3 damage increased with proximity to a known WNS-positive hibernaculum. Similarly, the number of bats with severe wing damage (scoring 2 or 3) was greater at sites closer to infected hibernacula, but little variance was explained by the trend. When species-specific BMI was examined, trends were consistent by sex (female BMI scores were higher than those of males), but no relationship was discovered between BMI and WDI scores. We conclude that, at this larger geographic scale, WDI is not a clear indicator of bat health.     

A decade of hibernating bat communities along the periphery of a region of white-nose syndrome

Long-term monitoring programs are necessary to assess populations for conservation planning and management decisions. Hibernating bats in North America have declined because of numerous natural and human-induced disturbances. White-nose syndrome (WNS) has become the most serious threat to North American cave-dwelling bats, leading to significant population declines in several species. We examined trends in hibernating bat populations at 11 hibernacula in northern Georgia and Alabama, USA, from 2013–2022, beginning when WNS was first detected in the region. Although we observed interannual variation in numbers of the federally endangered gray bat (Myotis grisescens), mean counts remained stable over time. In contrast, the tricolored bat (Perimyotis subflavus) and the federally endangered northern long-eared bat (M. septentrionalis) declined by >90% in the first 5 years after WNS detection in the region. Although no northern long-eared bats have been reported since 2019, tricolored bat counts stabilized following initial declines. Understanding changes in bat populations as WNS continues to spread, and determining the extent of population declines, is necessary for making appropriate management decisions. Our findings elucidate the status of cave-dwelling bat species along the periphery of the white-nose syndrome endemic region and highlight the importance of monitoring bat communities on a regional scale to develop effective conservation strategies.     

Specific alterations in complement protein activity of little brown myotis (Myotis lucifugus) hibernating in white-nose syndrome affected sites

White-nose syndrome (WNS) is the most devastating condition ever reported for hibernating bats, causing widespread mortality in the northeastern United States. The syndrome is characterized by cutaneous lesions caused by a recently identified psychrophilic and keratinophylic fungus (Geomyces destructans), depleted fat reserves, atypical behavior, and damage to wings; however, the proximate cause of mortality is still uncertain. To assess relative levels of immunocompetence in bats hibernating in WNS-affected sites compared with levels in unaffected bats, we describe blood plasma complement protein activity in hibernating little brown myotis (Myotis lucifugus) based on microbicidal competence assays using Escherichia coli, Staphylococcus aureus and Candida albicans. Blood plasma from bats collected during mid-hibernation at WNS-affected sites had higher bactericidal ability against E. coli and S. aureus, but lower fungicidal ability against C. albicans when compared with blood plasma from bats collected at unaffected sites. Within affected sites during mid-hibernation, we observed no difference in microbicidal ability between bats displaying obvious fungal infections compared to those without. Bactericidal ability against E. coli decreased significantly as hibernation progressed in bats collected from an affected site. Bactericidal ability against E. coli and fungicidal ability against C. albicans were positively correlated with body mass index (BMI) during late hibernation. We also compared complement activity against the three microbes within individuals and found that the ability of blood plasma from hibernating M. lucifugus to lyse microbial cells differed as follows: E. coli>S. aureus>C. albicans. Overall, bats affected by WNS experience both relatively elevated and reduced innate immune responses depending on the microbe tested, although the cause of observed immunological changes remains unknown. Additionally, considerable trade-offs may exist between energy conservation and immunological responses. Relationships between immune activity and torpor, including associated energy expenditure, are likely critical components in the development of WNS.     

DNA-based detection of the fungal pathogen Geomyces destructans in soils from bat hibernacula

White-nose syndrome (WNS) is an emerging disease causing unprecedented morbidity and mortality among bats in eastern North America. The disease is characterized by cutaneous infection of hibernating bats by the psychrophilic fungus Geomyces destructans. Detection of G. destructans in environments occupied by bats will be critical for WNS surveillance, management and characterization of the fungal lifecycle. We initiated an rRNA gene region-based molecular survey to characterize the distribution of G. destructans in soil samples collected from bat hibernacula in the eastern United States with an existing PCR test. Although this test did not specifically detect G. destructans in soil samples based on a presence/absence metric, it did favor amplification of DNA from putative Geomyces species. Cloning and sequencing of PCR products amplified from 24 soil samples revealed 74 unique sequence variants representing 12 clades. Clones with exact sequence matches to G. destructans were identified in three of 19 soil samples from hibernacula in states where WNS is known to occur. Geomyces destructans was not identified in an additional five samples collected outside the region where WNS has been documented. This study highlights the diversity of putative Geomyces spp. in soil from bat hibernacula and indicates that further research is needed to better define the taxonomy of this genus and to develop enhanced diagnostic tests for rapid and specific detection of G. destructans in environmental samples.     

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

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 to 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 nonwintering habitat may be valuable strategies for assessing and promoting recovery of WNS‐affected bat populations.     

Population dynamics of little brown bats (Myotis lucifugus) at summer roosts: Apparent survival,fidelity, abundance,and the influence of winter conditions

1. White‐nose syndrome (WNS) has caused the death of millions of bats, but the impacts have been more difficult to identify in western North America. Understanding how WNS, or other threats, impacts western bats may require monitoring other roosts, such as maternity roosts and night roosts, where bats aggregate in large numbers.
2. Little brown bats (Myotis lucifugus) are experiencing some of the greatest declines from WNS. Estimating survival and understanding population dynamics can provide valuable data for assessing population declines and informing conservation efforts.
3. We conducted a 5‐year mark–recapture study of two M. lucifugus roosts in Colorado. We used the robust design model to estimate apparent survival, fidelity, and abundance to understand population dynamics, and environmental covariates to understand how summer and winter weather conditions impact adult female survival. We compared the fidelity and capture probability of M. lucifugus between colonies to understand how bats use such roosts.
4. Overwinter survival increased with the number of days with temperatures below freezing (β > 0.100, SE = 0.003) and decreased with the number of days with snow cover (β < −0.40, SE < 0.13). Adult female fidelity was higher at one maternity roost than the other. Overwinter and oversummer adult female survival was high (>0.90), and based on survival estimates and fungal‐swabbing results, we believe these populations have yet to experience WNS.
5. Recapture of M. lucifugus using antennas that continuously read passive integrated transponder tags allows rigorous estimation of bat population parameters that can elucidate trends in abundance and changes in survival. Monitoring populations at summer roosts can provide unique population ecology data that monitoring hibernacula alone may not. Because few adult males are captured at maternity colonies, and juvenile males have low fidelity, additional effort should focus on understanding male M. lucifugus population dynamics.

     

Free-Ranging Little Brown Myotis (Myotis lucifugus) Heal from Wing Damage Associated with White-Nose Syndrome

White-nose syndrome (WNS) is having an unprecedented impact on hibernating bat populations in the eastern United States. While most studies have focused on widespread mortality observed at winter hibernacula, few have examined the consequences of wing damage that has been observed among those bats that survive hibernation. Given that WNS-related wing damage may lead to life-threatening changes in wing function, we tested the hypothesis that reduced abundance of free-ranging little brown myotis (Myotis lucifugus) with severe wing damage as the summer progresses is due to healing of wing tissue. Photographs of captured and recaptured adult females were examined for wing damage and healing rates were calculated for each category of wing damage index (WDI = 0–3). We found that free-ranging bats with severe wing damage were able to heal to a lower WDI score within 2 weeks. Bats with the most severe wing damage had faster healing rates than did individuals with less damage. We also found a significant relationship between body condition and WDI for adult females captured in the early weeks of the active season. Our results support the hypothesis that some bats can heal from severe wing damage during the active season, and thus may not experience increased mortality associated with reduced functions of wings. We urge researchers and wildlife managers to use caution when interpreting data on WDI to assess the impact of WNS on bat populations, especially during the later months of the active season.     

Changes in hibernating tricolored bat (Perimyotis subflavus) roosting behavior in response to white‐nose syndrome

Understanding animals'' behavioral and physiological responses to pathogenic diseases is critical for management and conservation. One such disease, white‐nose syndrome (WNS), has greatly affected bat populations throughout eastern North America leading to significant population declines in several species. Although tricolored bat (Perimyotis subflavus) populations have experienced significant declines, little research has been conducted on their responses to the disease, particularly in the southeastern United States. Our objective was to document changes in tricolored bat roost site use after the appearance of WNS in a hibernaculum in the southeastern U.S. and relate these to microsite temperatures, ambient conditions, and population trends. We censused a tricolored bat hibernaculum in northwestern South Carolina, USA, once each year between February 26 and March 2, 2014–2021, and recorded species, section of the tunnel, distance from the entrance, and wall temperature next to each bat. The number of tricolored bats in the hibernaculum dropped by 90.3% during the first 3 years after the arrival of WNS. However, numbers stabilized and slightly increased from 2018 to 2021. Prior to the arrival of WNS, 95.6% of tricolored bats roosted in the back portion of the tunnel that was the warmest. After the arrival of WNS, we observed a significant increase in the proportion of bats using the front, colder portions of the tunnel, particularly during the period of population stabilization and increase. Roost temperatures of bats were also positively associated with February external temperatures. Our results suggest that greater use of the colder sections of the tunnel by tricolored bats could have led to increased survival due to slower growth rates of the fungus that causes WNS in colder temperatures or decreased energetic costs associated with colder hibernation temperatures. Thus, management actions that provide cold hibernacula may be an option for long‐term management of hibernacula, particularly in southern regions.     

Winter behavior of bats and the progression of white‐nose syndrome in the southeastern United States

Understanding the winter behavior of bats in temperate North America can provide insight into how bats react to perturbations caused by natural disturbances such as weather, human‐induced disturbances, or the introduction of disease. This study measured the activity patterns of bats outside of their hibernaculum and asked how this winter activity varied by time, temperature, bat species, body condition, and WNS status. Over the course of three winters (2011–2013), we collected acoustic data and captured bats outside of five hibernacula in Tennessee, United States. During this time, Pseudogymnoascus destructans, the causative agent of white‐nose syndrome, became established in hibernacula throughout the region, allowing us to track disease‐related changes in the winter behavior of ten bat species. We determined that bats in the southeastern United States were active during winter regardless of disease. We recorded activity outside of hibernacula at temperatures as low as ?13°C. Although bat activity was best determined by a combination of variables, the strongest factor was mean daily temperature (R ² = .2879, F _1,1450 = 586.2, p  < .0001). Bats that left the hibernacula earlier in evening had lower body condition than those that left 2–4 hr after sunset (F _7,932 = 7.225, p  < .0001, Tukey HSD, p  < .05). The number of daytime emergences from hibernacula, as determined via acoustic detection, increased the longer a site was P. destructans positive (F _{3,17 808} = 124.48, p  < .0001, Tukey HSD, p  < .05). Through the use of passive acoustic monitoring and monthly captures, we determined that winter activity was driven by both ambient temperature and the presence of P. destructans .     

Evaporative water loss is a plausible explanation for mortality of bats from white-nose syndrome

White-nose syndrome (WNS) has caused alarming declines of North American bat populations in the 5 years since its discovery. Affected bats appear to starve during hibernation, possibly because of disruption of normal cycles of torpor and arousal. The importance of hydration state and evaporative water loss (EWL) for influencing the duration of torpor bouts in hibernating mammals recently led to "the dehydration hypothesis," that cutaneous infection of the wing membranes of bats with the fungus Geomyces destructans causes dehydration which in turn, increases arousal frequency during hibernation. This hypothesis predicts that uninfected individuals of species most susceptible to WNS, like little brown bats (Myotis lucifugus), exhibit high rates of EWL compared to less susceptible species. We tested the feasibility of this prediction using data from the literature and new data quantifying EWL in Natterer's bats (Myotis nattereri), a species that is, like other European bats, sympatric with G. destructans but does not appear to suffer significant mortality from WNS. We found that little brown bats exhibited significantly higher rates of normothermic EWL than did other bat species for which comparable EWL data are available. We also found that Natterer's bats exhibited significantly lower rates of EWL, in both wet and dry air, compared with values predicted for little brown bats exposed to identical relative humidity (RH). We used a population model to show that the increase in EWL required to cause the pattern of mortality observed for WNS-affected little brown bats was small, equivalent to a solitary bat hibernating exposed to RH of ～95%, or clusters hibernating in ～87% RH, as opposed to typical near-saturation conditions. Both of these results suggest the dehydration hypothesis is plausible and worth pursuing as a possible explanation for mortality of bats from WNS.     

Temperature-Dependent Growth of Geomyces destructans,the Fungus That Causes Bat White-Nose Syndrome

White-nose syndrome (WNS) is an emergent disease estimated to have killed over five million North American bats. Caused by the psychrophilic fungus Geomyces destructans, WNS specifically affects bats during hibernation. We describe temperature-dependent growth performance and morphology for six independent isolates of G. destructans from North America and Europe. Thermal performance curves for all isolates displayed an intermediate peak with rapid decline in performance above the peak. Optimal temperatures for growth were between 12.5 and 15.8°C, and the upper critical temperature for growth was between 19.0 and 19.8°C. Growth rates varied across isolates, irrespective of geographic origin, and above 12°C all isolates displayed atypical morphology that may have implications for proliferation of the fungus. This study demonstrates that small variations in temperature, consistent with those inherent of bat hibernacula, affect growth performance and physiology of G. destructans, which may influence temperature-dependent progression and severity of WNS in wild bats.     

Roost selection by Formosan leaf-nosed bats (Hipposideros armiger terasensis)

Patterns of roost use by Formosan leaf-nosed bats (Hipposideros armiger terasensis) were studied from November 1998 to April 2000. Structural characteristics, microclimates, and disturbance levels of 17 roosts used by H. a. terasensis and 15 roosts either used by other bat species (2) or not occupied by any bat species were compared. Roosts used by these bats were significantly larger in size and had greater areas covered by water compared to unused roosts. Entrances of active roosts were more likely to be east-west oriented. Hibernacula had lower entrances and ceilings than did roosts used only in summer. Higher temperatures were recorded in non-breeding roosts than in breeding roosts, but temperature gradients in these two types of roosts did not differ. In winter, hibernacula were warmer, and the temperature fluctuated less than in non-hibernacula. The relative humidities in summer roosts and hibernacula were nearly 100%. Disturbance levels were significantly higher in non-breeding roosts than in breeding roosts, and in non-hibernacula than in hibernacula. These results suggest that the Formosan leaf-nosed bats are selective of their roosts, but the pattern of their roost selection differs from those reported for bats of temperate regions. The reasons for such differences may be related to differences in body size, behavior, and reproductive strategy of the Formosan leaf-nosed bats living in a subtropical climate in Taiwan.     

Use of predictive distribution models to describe habitat selection by bats in Colorado,USA

Numerous processes operating at landscape scales threaten bats (e.g., habitat loss, disease). Temperate bat species are rarely examined at commensurate scales because of logistical and modeling constraints. Recent modeling approaches now allow for presence-only datasets, like those often available for bats, to assist with the development of predictive distribution models. We describe the use of presence-only data and rigorous predictive distribution models to examine habitat selection by bats across Colorado, USA. We applied hierarchical Bayesian models to bat locations from 1906–2018 to examine relationships of 13 species with landscape covariates. We considered differences in type of activity (foraging, roosting, hibernation), seasonality (summer vs. winter), and scale (1, 5, 10, and 15-km buffers). These findings generated statewide probability of use models to guide management of bat species in response to threats (e.g., white-nose syndrome [WNS]). Analysis of buffers suggest selection of land cover and environmental covariates occurs at different scales depending on the species and activity. Pinyon (Pinus spp.)-juniper (Juniperus spp.) appeared as a positive association in the highest number of models, followed by montane woodland, supporting the importance of these forest types to bats in Colorado. Other covariates commonly associated with bats in Colorado include westerly longitudes, and negative associations with montane shrubland. Mechanical treatments within pinyon-juniper and montane woodlands should be conducted with caution to avoid harming bat communities. We developed hibernation models for only 2 species, making apparent the lack of winter records for bat species in the state. We also provide a composite predictive surface of small-bodied bats in Colorado that delineates where these species, vulnerable to WNS, converge. This tool provides managers with focal points to apply surveillance and response strategies for the impending arrival of the disease.     

Frequent arousal from hibernation linked to severity of infection and mortality in bats with white-nose syndrome

White-nose syndrome (WNS), an emerging infectious disease that has killed over 5.5 million hibernating bats, is named for the causative agent, a white fungus (Geomyces destructans (Gd)) that invades the skin of torpid bats. During hibernation, arousals to warm (euthermic) body temperatures are normal but deplete fat stores. Temperature-sensitive dataloggers were attached to the backs of 504 free-ranging little brown bats (Myotis lucifugus) in hibernacula located throughout the northeastern USA. Dataloggers were retrieved at the end of the hibernation season and complete profiles of skin temperature data were available from 83 bats, which were categorized as: (1) unaffected, (2) WNS-affected but alive at time of datalogger removal, or (3) WNS-affected but found dead at time of datalogger removal. Histological confirmation of WNS severity (as indexed by degree of fungal infection) as well as confirmation of presence/absence of DNA from Gd by PCR was determined for 26 animals. We demonstrated that WNS-affected bats aroused to euthermic body temperatures more frequently than unaffected bats, likely contributing to subsequent mortality. Within the subset of WNS-affected bats that were found dead at the time of datalogger removal, the number of arousal bouts since datalogger attachment significantly predicted date of death. Additionally, the severity of cutaneous Gd infection correlated with the number of arousal episodes from torpor during hibernation. Thus, increased frequency of arousal from torpor likely contributes to WNS-associated mortality, but the question of how Gd infection induces increased arousals remains unanswered.     

Recovery of little brown bats (Myotis lucifugus) from natural infection with Geomyces destructans, white-nose syndrome

Geomyces destructans produces the white fungal growth on the muzzle and the tacky white discoloration on wings and ears that characterize white-nose syndrome (WNS) in cave-hibernating bats. To test the hypothesis that postemergent WNS-infected bats recover from infection with G. destructans, 30 little brown bats (Myotis lucifugus) were collected in May 2009 from a WNS-affected hibernation site in New Jersey. All bats were confirmed to be infected with G. destructans using a noninvasive fungal tape method to identify the conidia of G. destructans and polymerase chain reaction (PCR). The bats were then held in captivity and given supportive care for 70 days. Of the 26 bats that survived and were humanely killed after 70 days, 25 showed significant improvement in the external appearance of wing membranes, had no microscopic evidence of infection by G. destructans, and had wing tissue samples that were negative for G. destructans by PCR. A subset of the bats was treated topically at the beginning of the rehabilitation study with a dilute vinegar solution, but treatment with vinegar provided no added advantage to recovery. Provision of supportive care to homeothermic bats was sufficient for full recovery from WNS. One bat at day 70 still had both gross pathology and microscopic evidence of WNS in wing membranes and was PCR-positive for G. destructans. Dense aggregates of neutrophils surrounded the hyphae that remained in the wing membrane of this bat.     

Long‐term changes in bat activity in Quebec suggest climatic responses and summer niche partitioning associated with white‐nose syndrome

In North America, the greatest and most sudden threat to hibernating bats is white‐nose syndrome (WNS), which has caused massive declines in populations since 2006. Other determinants of bat dynamics, such as the climate, and the effect of reduction in the number of individuals sharing foraging space and summer roosting habitat may have an effect on population dynamics. We analyzed transect acoustic bat surveys conducted with ultrasonic detectors in 16 regions in Quebec, Canada, between 2000 and 2015. We used piecewise regression to describe changes in activity over time for each species and a meta‐analytic approach to measure its association with the North Atlantic Oscillation (NAO). As expected, mouse‐eared bat (Myotis spp.) activity sharply declined after the onset of WNS, down by 79% after 3 years. In contrast, big brown/silver‐haired bat activity increased over the same period, possibly due to a release of competition. Hoary bats and red bats remained present, although their activity did not increase. Myotis activity was positively correlated with a one‐year lag to the NAO index, associated with cold conditions in winter, but warm autumns. Big brown/silver‐haired and hoary bats were also more active during NAO‐positive years but without a lag. We conclude that combinations of threats may create rapid shifts in community compositions and that a more balanced research agenda that integrates a wider range of threats would help better understand and manage those changes.