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Temperate bats exhibit seasonal and sex differences in resource selection and activity patterns that are influenced by ambient conditions. During fall, individuals face energetic trade-offs as they make choices relating to migration, mating, and hibernation that may diverge for populations throughout their range. However, research has largely focused on the summer maternity and winter hibernation seasons, whereas the prehibernation period remains comparatively understudied. Northern Myotis (Myotis septentrionalis) have experienced precipitous population declines from white-nose syndrome (WNS), leading to their protected status in the United States and Canada. Therefore, understanding their ecology throughout the year is paramount to inform conservation. We compared seasonal roosts and documented fall behaviors between study sites and sexes on 3 islands: Long Island (New York), Martha's Vineyard, and Nantucket Island (Massachusetts). Between 2017 and 2020, we radio-tracked 54 individuals to analyze activity patterns and characterize fall roosts to compare with previously known summer roosts. Summer tree roosts were of smaller diameter, later stages of decay, and lower canopy closure than those used in fall. Both sexes selected trees of similar diameter and decay stage during fall. Anthropogenic roost use was documented in both seasons but use of anthropogenic structures was greater during fall and increased as the season progressed. Bats made short inter-roost movements with males traveling greater distances than females on average. Activity occurred until late November, with males exhibiting a longer active period than females. We tracked 23% of tagged bats to local hibernacula in subterranean anthropogenic structures, the majority of which were crawlspaces underneath houses. Use of anthropogenic structures for roosts and hibernacula may facilitate survival of this species in coastal regions despite the presence of WNS infections. Timing of restrictions on forest management activities for bat conservation may be mismatched based on prehibernation activity observed in these coastal populations, and the conservation of habitat surrounding anthropogenic roosts or hibernacula may be warranted if the structures themselves cannot be protected. [ABSTRACT FROM AUTHOR]

Bats frequently inhabit caves and other subterranean habitats and play a critical role in subterranean food webs. With escalating threats to subterranean ecosystems, identifying the most effective measures to protect subterranean‐roosting bats is critical. We conducted a meta‐analysis to evaluate the effectiveness of conservation and management interventions for subterranean‐roosting bats. We used network analyses to determine to what extent interventions for bats overlap those used for other subterranean taxa. We conducted our analyses with data extracted from 345 papers recommending a total of 910 conservation interventions. Gating of roost entrances was applied to preserve bat populations in 21 studies, but its effectiveness was unclear. Habitat restoration and disturbance reduction positively affected bat populations and bat behavior, respectively, in ≤4 studies. Decontamination was assessed in 2 studies and positively affected bat populations, particularly in studies focused on reducing fungal spores associated with white‐nose syndrome in North America. Monitoring of bat populations as an effective conservation strategy was unclear and infrequently tested. Only 4% of bat studies simultaneously considered other subterranean organisms. However, effective interventions for bat conservation had similarities with all other organisms. If other subterranean organisms are considered when applying interventions to conserve bats, they might also benefit. [ABSTRACT FROM AUTHOR]

Bats are hosts to a range of pathogens, which include zoonotic pathogens and pathogens of conservation concern. Brock Fenton's research on bat ecology has always balanced clear communication of potential health risks associated with bats and the need to communicate these risks precisely to avoid unnecessary persecution of bats. Here, we integrate Brock's work in the field of disease ecology with that of his students and collaborators and consider the potential advantages of studying disease ecology of bats within the Canadian context. The broad distribution of a few common species across the vast landscape of present-day Canada provides an opportunity to untangle the impacts of environmental variation on host–pathogen interactions and disease severity, particularly in the context of climate change. The varying migratory strategies and social structure of the bat species found in Canada could also facilitate informative interspecific studies to better understand how bat health is affected by interactions among rapid environmental changes, physiological traits, and the social behaviour of different species. We propose a series of priority research questions and approaches that could further our understanding of bat health and disease ecology in Canada, inspired by the work of Brock, his colleagues, and students. [ABSTRACT FROM AUTHOR]

In the United States, the discovery and spread of white-nose syndrome (WNS) has drastically changed how bats and caves are managed. The U.S. National Park Service has been instrumental in the national response to WNS, as it manages extensive cave resources and has a close relationship with the public. However, managers lack information on visitor support for disease prevention measures designed to slow the spread of WNS and minimize human disturbance of vulnerable bat populations. This study utilized the Theory of Planned Behavior to determine how visitor attitudes, subjective norms, and perceived behavioral controls influenced their behavior regarding WNS preventive actions, including participation in educational programming on bats, wearing clothes or shoes in caves that have not been contaminated with the fungus that causes WNS, walking over decontamination mats, and complying with cave closures. During summer of 2019, data were collected using an on-site survey of 1365 visitors to eight U.S. national park units: Oregon Caves, Lava Beds, Carlsbad Caverns, El Malpais, Wind Cave, Jewel Cave, Mammoth Cave, and Cumberland Gap. Visitors were willing to participate in all preventative actions addressed in the survey (77.7%-96.7%). Visitors expressed that engaging in these actions was very desirable (36.0%-65.6%), and their decision to engage in these actions was most strongly influenced by park staff (39.2%-68.8%) or signage (35.5%-61.9%). Attitudes and subjective norms were positive predictors of behavioral intentions for all measures. Perceived behavioral control was not a direct predictor for behavioral intent, but its interaction with attitudes and subjective norms had a moderating influence on intention to comply with multiple WNS preventive actions. With the continued spread of WNS and emergence of other threats to bats, understanding visitor behavioral intent and underlying factors will facilitate successful implementation of preventive actions that are publicly supported and promote conservation of bat populations in U.S. national parks. [ABSTRACT FROM AUTHOR]

White‐nose syndrome (WNS), a catastrophic fungal disease of hibernating bats, is perpetuated by environmental reservoirs of the fungal pathogen, Pseudogymnoascus destructans. Surviving bats clear infection each summer but are re‐infected upon return to the hibernaculum. Therefore, addressing environmental reservoirs is critical for managing WNS. Ultraviolet (UV) light is known to kill P. destructans in the lab, and whole‐room UV sanitization is a common practice in many commercial settings. However, effective UV treatment at the hibernaculum scale has yet to be confirmed. Importantly, existing standard practices likely require modification for implementation in hibernation sites. Prior to field testing, confirming the ability of UV sanitizers to treat the complex topography of hibernacula, as well as quantifying the effects of such topography on effective treatment times is necessary. Here we use a laboratory setting to investigate the feasibility of whole‐room UV‐C sanitization in treating environmental reservoirs of P. destructans. All trials resulted in mean fungal reductions of 97.3% (range: 91.9‐99.7%) relative to controls. To prepare for future implementation within a hibernaculum, we quantified the effect of distance, emission angle, and incidence angle on UV‐C irradiance delivered to target locations. From these data, we calculated treatment times required for killing P. destructans at the scale of a natural setting. Measurable UV‐C irradiance extended to a maximum distance of 21.3 m. Angles of emission and incidence both reduced irradiance; however, we conclude that ~325 m3 of surface volume could be treated in <2 h. Taken together, UV‐C sanitization may provide a feasible, scalable, and relatively ecologically benign method of reducing P. destructans populations. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Hibernation is widespread among mammals in a variety of environmental contexts. However, few experimental studies consider interspecific comparisons, which may provide insight into general patterns of hibernation strategies. We studied 13 species of free-living bats, including populations spread over thousands of kilometers and diverse habitats. We measured torpid metabolic rate (TMR) and evaporative water loss (two key parameters for understanding hibernation energetics) across a range of temperatures. There was no difference in minimum TMR among species (i.e., all species achieved similarly low torpid metabolic rate) but the temperature associated with minimum TMR varied among species. The minimum defended temperature (temperature below which TMR increased) varied from 8 °C to < 2 °C among species. Conversely, evaporative water loss varied among species, with species clustered in two groups representing high and low evaporative water loss. Notably, species that have suffered population declines due to white-nose syndrome fall in the high evaporative water loss group and less affected species in the low evaporative water loss group. Documenting general patterns of physiological diversity, and associated ecological implications, contributes to broader understanding of biodiversity, and may help predict which species are at greater risk of environmental and anthropogenic stressors. [ABSTRACT FROM AUTHOR]

Aim: The fungal pathogen Pseudogymnoascus destructans and resultant white‐nose syndrome (WNS) continues to advance across North America, infecting new bat hibernacula. Western North America hosts the highest bat diversity in the United States and Canada, yet little is known about hibernacula and hibernation behaviour in this region. An improved understanding of the distribution of suitable hibernacula is critical for land managers to anticipate conservation needs of WNS‐susceptible species in currently uninfected regions. Location: United States, Canada. Taxon: Bats. Methods: We estimated suitability of potential winter hibernaculum sites across five bat species' ranges. We estimated winter survival capacity from a mechanistic survivorship model based on bat bioenergetics and climate conditions. We then used boosted regression trees to relate these estimates, along with key landscape attributes, to bat occurrence data in a hybrid correlative‐mechanistic approach. Results: Winter survival capacity, topography, land cover and access to subterranean features were important predictors of winter hibernaculum selection, but the shape and relative importance of these relationships varied amongst species. This suggests that the occurrence of bat hibernacula can, in part, be predicted from readily mapped above‐ground features, not just below‐ground characteristics for which spatial data are lacking. Furthermore, our mechanistic estimate of winter survivorship was, on average, the third strongest predictor of winter occurrence probability across focal species. Main conclusions: Winter distributions of North American bat species were driven by their physiological capacity to survive winter conditions and duration in a given location, as well as selection for topographic and other landscape features but in species‐specific ways. The influence of winter survivorship on several species' distributions, the underlying influence of climate conditions on winter survivorship and the anticipated influence of WNS on bats' hibernation physiology and survivorship together suggest that North American bat distributions may undergo future shifts as these species are exposed not only to WNS but also to climate change. [ABSTRACT FROM AUTHOR]

Tricolored bats (Perimyotis subflavus) that roost in subterranean hibernacula have experienced precipitous declines from white-nose syndrome (WNS); however, understudied populations also use during winter non-subterranean roosts such as tree cavities, bridges, and foliage. Our objectives were to determine winter roost use by tricolored bats in an area devoid of subterranean roosts, determine roost microclimates to relate them to growth requirements of the fungal causal agent of WNS, and determine habitat factors influencing winter tree selection. From November to March 2017–2019, we used radiotelemetry to track 15 bats to their day roosts in the upper Coastal Plain of South Carolina and recorded microclimates in accessible tree cavities and bridges. We also characterized habitat and tree characteristics of 24 used trees and 153 random, available trees and used discrete choice models to determine selection. Roost structures included I-beam bridges, cavities in live trees, and foliage. Bridges were warmer and less humid than cavities. Roost temperatures often were amenable to fungal growth (< 19.5°C) but fluctuated widely depending on ambient temperatures. Bats used bridges on colder days (8.7°C ± 5.0 SD) and trees on warmer days (11.3°C ± 5.4). Bats selected low-decay trees closer to streams in areas with high canopy closure and cavity abundance. Bats also appeared to favor hardwood forests and avoid pine forests. Our results suggest that access to multiple roost microclimates might be important for tricolored bats during winter, and forest management practices that retain live trees near streams and foster cavity formation in hardwood forests likely will benefit this species. Our results also suggest tricolored bats using bridge and tree roosts might be less susceptible to WNS than bats using subterranean hibernaculum roosts. Thus, forests in areas without subterranean hibernacula in the southeastern United States that support bats during winter might represent important refugia from WNS for multiple species. [ABSTRACT FROM AUTHOR]

Temperate bat species use extended torpor to conserve energy when ambient temperatures are low and food resources are scarce. Previous research suggests that migratory bat species and species known to roost in thermally unstable locations, such as those that roost in trees, are more likely to remain active during winter. However, hibernating colonies of cave roosting bats in the southeastern United States may also be active and emerge from caves throughout the hibernation period. We report what bats are eating during these bouts of winter activity. We captured 2,044 bats of 10 species that emerged from six hibernacula over the course of 5 winters (October–April 2012/2013, 2013/2014, 2015/2016, 2016/2017, and 2017/2018). Using Next Generation sequencing of DNA from 284 fecal samples, we determined bats consumed at least 14 Orders of insect prey while active. Dietary composition did not vary among bat species; however, we did record variation in the dominant prey items represented in species' diets. We recorded Lepidoptera in the diet of 72.2% of individual Corynorhinus rafinesquii and 67.4% of individual Lasiurus borealis. Diptera were recorded in 32.4% of Myotis leibii, 37.4% of M. lucifugus, 35.5% of M. sodalis and 68.8% of Perimyotis subflavus. Our study is the first to use molecular genetic techniques to identify the winter diet of North American hibernating bats. The information from this study is integral to managing the landscape around bat hibernacula for insect prey, particularly in areas where hibernating bat populations are threatened by white-nose syndrome. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

White‐nose syndrome (WNS) has decimated hibernating bat populations across eastern and central North America for over a decade. Disease severity is driven by the interaction between bat characteristics, the cold‐loving fungal agent, and the hibernation environment. While we further improve hibernation energetics models, we have yet to examine how spatial heterogeneity in host traits is linked to survival in this disease system. Here, we develop predictive spatial models of body mass for the little brown myotis (Myotis lucifugus) and reassess previous definitions of the duration of hibernation of this species. Using data from published literature, public databases, local experts, and our own fieldwork, we fit a series of generalized linear models with hypothesized abiotic drivers to create distribution‐wide predictions of prehibernation body fat and hibernation duration. Our results provide improved estimations of hibernation duration and identify a scaling relationship between body mass and body fat; this relationship allows for the first continuous estimates of prehibernation body mass and fat across the species' distribution. We used these results to inform a hibernation energetic model to create spatially varying fat use estimates for M. lucifugus. These results predict WNS mortality of M. lucifugus populations in western North America may be comparable to the substantial die‐off observed in eastern and central populations. [ABSTRACT FROM AUTHOR]

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.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.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.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.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. [ABSTRACT FROM AUTHOR]

Understanding why private property owners take actions to conserve bats has become increasingly important in U.S. states where the fungus causing white-nose syndrome (Pseudogymnoascus destructans) has decimated bat populations. We surveyed property owners in three New York State counties (n = 2,500) and used multiple linear regression analyses to test predictors of intentions to conserve bats. Intentions to take actions that contribute to bat conservation directly were predicted by severity of rabies consequences, sense of bat conservation self efficacy, beliefs about responsibility for bat conservation, and attitudes toward bats (R2 =.39). Intentions to take actions that conserve bats indirectly were predicted by biospheric value orientations, beliefs about responsibility for bat conservation, and attitudes toward bats (R2 =.27). The relationship between beliefs about rabies and intentions to take actions that contribute to bat conservation highlights the need for coordinated risk communication between public health and wildlife conservation organizations. [ABSTRACT FROM AUTHOR]

Understanding frequency and variation of cave-exiting activity after arousal from torpor of hibernating bats is important for bat ecology and conservation, especially considering white-nose syndrome. In winter from 2011 to 2018, we acoustically monitored, and counted in hibernacula, two species of conservation concern—western small-footed myotis (Myotis ciliolabrum) and Townsend's big-eared bats (Corynorhinus townsendii)—in 9 caves located in important habitat for these species in western North America. We investigated if cave-exiting activity differed by species, cave, number of hibernating bats, moon phase, and weather variables. Both species exited hibernacula during all winter months, but most activity occurred in March followed by November. Although we counted almost 15 times more Townsend's big-eared bats during hibernacula surveys, we documented western small-footed myotis exiting caves 3 times more than Townsend's big-eared bats. Cave-exiting activity increased with increasing number of hibernating bats, but more so for western small-footed myotis. Both species of bats were active during warm weather and low wind speeds. Western small-footed myotis were more active during colder temperatures, higher wind speeds, and greater change in barometric pressure than Townsend's big-eared bats. Our results provide a long-term dataset of cave-exiting activity after arousal from torpor during hibernation for these species before the arrival of white-nose syndrome. [ABSTRACT FROM AUTHOR]

Low winter temperatures are a major driver of hibernation and migration in temperate North American bats. Hibernation and migration in turn affect bat mortality via white-nose syndrome and collisions with wind turbines. To describe winter bat acoustic activity across a wide temperature gradient and to understand species-specific responses to low temperatures, we recorded nightly acoustic activity of bats at 15 sites across the state of North Carolina, United States, from December through February 2016 – 2018. Bat acoustic activity was recorded at all sites during both winters. Nightly probability of bat acoustic presence regressed positively on ambient temperature. Nightly probability of presence in Lasionycteris noctivagans (silver-haired bat) and Eptesicus fuscus (big brown bat) regressed negatively on wind speed. The mean probability of presence within the same winter condition was highest for L. noctivagans , followed by E. fuscus , Perimyotis subflavus (tricolored bat), and Lasiurus cinereus (hoary bat). Differences in species' mean body weight and roosting preference explained part of the variation of the species-specific probability of presence. Our results can be used to predict bat acoustic presence for these species across the southeastern United States in winter, and better understand the potential threats to bats such as white-nose syndrome and wind turbine interactions. [ABSTRACT FROM AUTHOR]

Human perturbation of natural systems is accelerating the emergence of infectious diseases, mandating integration of disease and ecological research. Bats have been associated with recent zoonoses, but our bibliometric analysis of coauthor relationships identified a separation of bat ecologists and infectious disease researchers with few cross-disciplinary relationships. Of 5,645 papers, true interdisciplinary collaborations occurred primarily in research focused on White Nose Syndrome (WNS). This finding is important because it illustrates how research with outcomes favoring both bat conservation and disease mitigation promotes domain integration and network connectivity. We advocate for increased engagement between ecology and infectious researchers to address such common causes and suggest that efforts focus on leveraging existing activities, building interdisciplinary projects, and networking individuals and networks to integrate domains and coordinate resources. We provide specific opportunities for pursuing these strategies through the Bat One Health Research Network (BOHRN). Limited collaboration between bat ecologists and disease researchers has precluded integrative research on disease emergence. These historical silos are now challenged by the emergence of SARS-CoV-2, which threatens both human and bat health. This Perspective article maintains that interdisciplinary research can be accelerated when disparate domains address common, foundational causes. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Efforts to conserve bats in the western United States have long been impeded by a lack of information on their winter whereabouts, particularly bats in the genus Myotis. The recent arrival of white-nose syndrome in western North America has increased the urgency to characterize winter roost habitats in this region. We compiled 4,549 winter bat survey records from 2,888 unique structures across 11 western states. Myotis bats were reported from 18.5% of structures with 95% of aggregations composed of ≤10 individuals. Only 11 structures contained ≥100 Myotis individuals and 6 contained ≥500 individuals. Townsend’s big-eared bat (Corynorhinus townsendii) were reported from 38% of structures, with 72% of aggregations composed of ≤10 individuals. Aggregations of ≥100 Townsend’s big-eared bats were observed at 41 different caves or mines across 9 states. We used zero-inflated negative binomial regression to explore biogeographic patterns of winter roost counts. Myotis counts were greater in caves than mines, in more recent years, and in more easterly longitudes, northerly latitudes, higher elevations, and in areas with higher surface temperatures and lower precipitation. Townsend’s big-eared bat counts were greater in caves, during more recent years, and in more westerly longitudes. Karst topography was associated with higher Townsend’s big-eared bat counts but did not appear to influence Myotis counts. We found stable or slightly-increasing trends over time in counts for both Myotis and Townsend’s big-eared bats from 82 hibernacula surveyed ≥5 winters since 1990. Highly-dispersed winter roosting of Myotis in the western USA complicates efforts to monitor population trends and impacts of disease. However, our results reveal opportunities to monitor winter population status of Townsend’s big-eared bats across this region. [ABSTRACT FROM AUTHOR]

Although it is well documented that infectious diseases can pose threats to biodiversity, the potential long-term consequences of pathogen exposure on individual fitness and its effects on population viability have rarely been studied. We tested the hypothesis that pathogen exposure causes physiological carry-over effects with a pathogen that is uniquely suited to this question because the infection period is specific and time limited. The fungus Pseudogymnoascus destructans causes white-nose syndrome (WNS) in hibernating bats, which either die due to the infection while hibernating or recover following emergence from hibernation. The fungus infects all exposed individuals in an overwintering site simultaneously, and bats that survive infection during hibernation clear the pathogen within a few weeks following emergence. We quantified chronic stress during the active season, when bats are not infected, by measuring cortisol in bat claws. Free-ranging Myotis lucifugus who survived previous exposure to P. destructans had significantly higher levels of claw cortisol than naïve individuals. Thus, cryptic physiological carry-over effects of pathogen exposure may persist in asymptomatic, recovered individuals. If these effects result in reduced survival or reproductive success, they could also affect population viability and even act as a third stream in the extinction vortex. For example, significant increases in chronic stress, such as those indicated here, are correlated with reduced reproductive success in a number of species. Future research should directly explore the link between pathogen exposure and the viability of apparently recovered populations to improve understanding of the true impacts of infectious diseases on threatened populations. [ABSTRACT FROM AUTHOR]

• We performed 29 hibernacula surveys and set passive acoustic detectors in winter to detect bat cave-exiting activity. • Recordings of bats flying out of caves were related to number of hibernating bats. • Researchers can estimate number of hibernating bats using passive acoustic data. • Our methods could facilitate long-term monitoring of bats in caves. Many bat species in North America face precarious futures due to white-nose syndrome and wind energy development. These threats, and others, make it imperative to monitor long-term population fluctuations of bats. Counting hibernating bats in caves estimates abundance of these cave-dwelling mammals, and such counts can be used to understand population fluctuations across time. Passive acoustic monitoring can capture large amounts of long-term data that are standardized, scalable, and reproducible; these data can also be archived for future analyses. Little work has been done, however, assessing the relationship between recorded acoustic data from bats that arouse from torpor during hibernation and fly out of caves and number of bats counted in hibernacula. We acoustically monitored and counted two species of bats in 9 hibernacula from November to March 2011 to 2018. We hypothesized that acoustic data recorded from Townsend's big-eared bats (Corynorhinus townsendii) and western small-footed myotis (Myotis ciliolabrum) exiting hibernacula could be used to estimate abundance of those species in hibernacula. Over seven years, we conducted 29 hibernacula surveys and simultaneously set passive acoustic detectors during winter when those surveys were conducted. Acoustic monitors recorded for 1,063 nights. Detectors recorded 2,459 files of Townsend's big-eared bats and 9,094 files of western small-footed myotis. Across all years and hibernacula, mean number of Townsend's big-eared bats counted in a cave was 96; mean number of western small-footed myotis counted in a cave was 7. For Townsend's big-eared bats, the top model held 43% of model weight and included the variables bat activity (i.e., mean number of Anabat files/night) and cave. For western small-footed myotis, the top model held 55% of model weight and contained the variable bat activity. Mean number of acoustic recordings of bats flying out of a cave across a winter was positively related to number of hibernating bats counted in a cave in a year for western small-footed myotis—with greater variability for estimates with a larger number of acoustic files recorded of bats flying out of caves; for Townsend's big-eared bats that relationship held for 2 caves with > 90 individuals. Our results indicate that researchers can use passive acoustic data as an index of abundance of bats hibernating in caves in temperate climate zones. Additionally, our data indicate that researchers can acoustically detect hibernating western small-footed myotis even when these bats are not observed during hibernacula surveys. This monitoring can minimize the potential effect of researchers on the behavior of bats, facilitate long-term monitoring, and reduce the number of occasions that biologists enter caves to count bats. [ABSTRACT FROM AUTHOR]

Bats (Vespertilionidae and Phyllostomidae) are a critically important component of North American ecosystems. These insectivorous mammals provide largely unrecognized ecosystem services to agriculture and forest health and sustain bat-dependent native plant populations. The decline of North American bat populations reflects the recent emergence of the fungal disease white nose syndrome (WNS); susceptibility to pollutants; and rapid changes occurring in the North American landscape, such as energy development and associated forest fragmentation and loss. Hickories (Carya L. spp. [Juglandaceae]) are an important roost tree for bats in the eastern US, and we describe how to propagate them in bareroot nurseries. [ABSTRACT FROM AUTHOR]