Bat Roosts Research Articles

Bat box monitoring: testing the efficacy of eDNA to confirm box use

ABSTRACT Bat boxes can be employed to provide short-term mitigation for the loss of trees with bat roost potential. Traditionally bat box utilisation (by long-tailed bats) has been difficult to confirm in NZ, partly due to a lack of published survey techniques to confirm bat box utilisation when bats are not present at the time of sampling. While environmental deoxyribonucleic acid (eDNA) has been widely applied as a biomonitoring tool, it has not been used previously in the context of bat box surveys in New Zealand. Here we present a method for collecting eDNA from bat boxes using swabs and test the efficacy of eDNA in validating bat box utilisation as confirmation of roosting. Bat boxes were deployed by the Hamilton City Council as part of the bat mitigation strategy for the Southern Links Project in southern Hamilton. The eDNA method confirmed a total of 25 boxes out of the 73 (34%) included in this study were being utilised by long-tailed bats. The results indicate that eDNA can be applied with confidence to demonstrate box use, even at very low and infrequent occupancy rates.

Tricolored Bat (Perimyotis subflavus) microsite use throughout hibernation

Abstract White-nose syndrome (WNS) has caused dramatic population declines in several bat species, including the Tricolored Bat (Perimyotis subflavus). Several studies have documented bats using colder roosting temperatures after infection; however, this strategy may have costs such as increased freezing risks or greater predation risks and it is unknown when during hibernation bats begin to utilize these colder temperatures. Our aim was to examine Tricolored Bat roost locations in a WNS-positive site in relation to roost microclimate and other environmental conditions throughout the hibernation season. We conducted monthly censuses of tricolored bats across 2 hibernation seasons (November to March 2020 to 2021 and October to March 2021 to 2022) in a WNS-positive hibernaculum in northwestern South Carolina and recorded skin and adjacent wall temperature, tunnel section, and distance from the entrance for each bat species. We continuously measured hibernacula temperature and relative humidity during both hibernation seasons. Most bats roosted in the back part of the tunnel where temperatures were warmer and more stable, and vapor pressure deficit (VPD) and human disturbance were low. However, >20% of bats roosted in the front, where roost temperatures were significantly colder and VPD was higher but more variable; human disturbance was also higher in this section. The proportion of bats in each tunnel section did not vary among months and we did not find evidence of significant movement to the front section of the tunnel as hibernation progressed based on marked bats; however, bats in the front section roosted higher on the wall suggesting that they may be avoiding human disturbance or predators. Our results support the notion that no optimum hibernation temperature exists for tricolored bats and that high VPD and disturbance are likely important factors driving microsite use. Protection of Tricolored Bat hibernacula that offer a range of microclimates or a network of sites in close proximity that offer different microclimates may be helpful for recovery of this species.

Bat box monitoring: comparing multiple contemporary methods

ABSTRACT Bat boxes can be employed to provide mitigation for the loss of trees with bat roost potential. Eighty bat boxes were deployed by the Hamilton City Council as part of the bat mitigation strategy for the Southern Links Project in southern Hamilton. Several contemporary methods were employed to determine bat box occupancy to ensure effective monitoring. This included visual scoring assessments (e.g. staining, wetness), endoscope surveys, thermal imaging, and eDNA. Emergence survey data were provided by the University of Waikato which provided further insight into the accuracy of the methods. Jointly the methods confirmed the use of 34 Kent style boxes (n = 70; 49%). Indicating a high success rate of box utilisation over a relatively short period (two years). Of the methods, eDNA confirmed the largest percentage of bat box use. Comparatively, thermal imaging provided an alternative and less intrusive means of surveying on-the-day bat presence. However, there were instances where survey conditions (e.g. terrain, vegetation clutter, solar irradiance, rainfall) influenced the reliability of thermal imaging. While visual assessment and thermal imaging cannot be solely relied on, they provide a supportive tool for other monitoring techniques. They can help guide the application of more definitive methods such as eDNA.

High Resource Overlap and a Consistently Generalised Pattern of Interactions in a Bat-Flower Network in a Seasonally Dry Landscape.

Pollination is an ecosystem process that is crucial to maintain biodiversity and ecosystem function. Bats are important pollinators in the tropics and are an integral part of complex plant-pollinator interaction networks. However, network analysis-based approaches are still scarce at the plant species and bat community levels. We used metabarcoding to identify plant taxa present in pollen from fur and faecal samples collected across 1 year from three nectar-feeding bat roosts in central Mexico. We calculated the frequency of occurrence of plant taxa and assembled a zoocentric network of bat-plant interactions. We constructed a year-long network, encompassing the entire period of sampling, two seasonal networks comprising the wet and dry seasons, and six individual networks from sampling at two-month intervals across the year. Four species of nectar-feeding bats interacted with 36 plant species from 16 families. We found highly generalised interaction patterns across networks corresponding with opportunistic feeding behaviour by bats, with little seasonal variation in network structure. There was high resource overlap between bat species, and bats visited a diverse range of plant species even during periods with a high abundance of particular resources in the landscape. The diverse diet of nectar-feeding bats emphasises the importance of floristically rich natural habitats in the landscape to provide reliable foraging resources year-round in a seasonally variable system. While a generalised network structure is thought to increase robustness, further research is necessary to understand how fluctuations in pollinator abundance and diversity in the face of land use and climate change may impact bat-flower networks and the consequences to plant communities.

Study on Population and Roosting Ecology of Bats in and Around Chikkamagaluru

Bats spend over half of their lives in their roost environment, so these eventually play a prominent role in their ecology and evolution. Roosts are vital to the bats as it is plays where they actively get involved in mating, rearing offspring’s and facilitate the social living. With this background, the present study has been planned to evaluate the ecobiology of the bats in the vicinity of Chikkamagaluru. It is situated roughly in the south western part of Karnataka exists in mid-Western Ghats. The population dynamics of bat roosts were studied by emergence Count and direct roost count method. The roosting trees were identified by using standard botanical taxonomic keys. Bats roosted much more in trees belonging to Fabaceae family (1,527) followed by Myrtaceae family (1,180), Moraceae family (519), Bignoniaceae family (253), Sapindiaceae family (202), Proteaceae family (103), and very less population found in Poaceae family (21). Bat roosted much more in Pipal tree (40.72%), Red buckeye (26.03%), Banyan tree (19.97%), Rubber tree (6.18%), Avenue tree (3.22%), Bamboo (2.7%) and very less population in Tamarind tree (1.15%) in rural side of the study area. Where as in the city premises bats roosted much more in Nilgiri tree (38.19%), followed by Blue jacaranda tree (29.72%), White locust tree (25.26%) and very less roosting of bats in Silver tree (6.81%).In the present survey the population of bats and hosting trees varies from one locality to another locality. This is because of variation in vegetation, environmental condition and more or less adoptability of food and water and the less or more predators. The present study showed that bats preferred to roost in taller and larger trees having greater canopy areas as roosting sites, because these trees could provide more space for their large colonies.

Importance of Heritage Structures as Bat Roosts in the Sahara Desert

ABSTRACTIn addition to the availability of water and invertebrate prey, roost sites are considered the main factors enabling bats to survive in desert areas. Because suitable roost sites are often limiting resources, human constructions are also important for these animals. Conversely, in the context of built heritage conservation, bats are often discussed as a cause of damages. However, if historic structures deteriorate, they may lose their suitability as roosting sites for bats. This study examines how the condition of domed tombs in Sudan affects their use by bats. Inspections of 19 tombs revealed that bats occupied only undamaged structures, with 1652 individuals of four species found. Slightly and partially damaged tombs were not used by bats. These findings highlight the importance of preserving man‐made structures as critical roosting sites in arid environments to support local bat populations.

Population Size and Spatial Distribution of the Mexican Blind Cavefish (Astyanax) within the Caves

The most studied cavefish in the world is Astyanax mexicanus, and the most frequently used specimens in research come from the Pachón cave in Northeast Mexico. A recent study using the capture–mark–recapture technique revealed that the Pachón population size is only in the hundreds of individuals, not in the thousands. This result raises serious concerns about their long-term survival and highlights the need to accurately estimate the population size of other Astyanax caves. In our study, we used a well-established, non-invasive method for estimating population size: the transect sampling method, which counts the abundance of organisms along a line at regular intervals. We used the 310 m long Sabinos Cave’s Pool #1 for measurements and estimated a population of 1142 individuals. Most importantly, we found that cavefish are not distributed uniformly: 68% of the individuals were clustered under a bat roost. To corroborate this observation, we used drones to explore submerged galleries inaccessible to scientists. Results from the Toro/Calera Cave system confirmed that most galleries were essentially void of cavefish, except for in those few areas with high amounts of nutrients. Scientists visiting the most studied Astyanax localities (Pachón, Sabinos, Tinaja, and Chica) experience what appear to be high-density populations of about 10 fish/m2, possibly because the pool they visit happens to be under bat roosts. Our study shows that one cannot extrapolate the density at these localities to the rest of the habitat, where densities might be two orders of magnitude lower. Future studies should consider that the apparent high density at visited sites is overrepresenting the total population size when calculating the number of fish specimens to be captured.

Heterogenous effects of bat declines from white‐nose syndrome on arthropods

AbstractIn North America, white‐nose syndrome (WNS) has caused precipitous declines in hibernating bat populations, raising the question of whether the rapid loss of arthropodivorous bats may affect the abundance of their prey. During the summers of 2015–2018 (1 year after the arrival of WNS in Wisconsin, USA), we performed intensive arthropod black‐light trapping, ultrasonic acoustic monitoring, and emergence counts at 10 little brown (Myotis lucifugus) and big brown (Eptesicus fuscus) bat maternity roosts with paired control sites. For little brown bats, which are severely affected by WNS, roost counts declined by 95% over the four‐year period, compared to a 38% decline in big brown bat roost counts. Total arthropod abundance decreased by 49%, although decreases among common little brown bat prey were less severe. Our natural predator exclusion experiment supports existing evidence that bats can have measurable trophic impacts on arthropod communities, primarily via top‐down effects on common prey.

Ochaechulla spinturniciformis, a new genus and species of mite in the family Laelapidae (Acari: Mesostigmata) from Slovakia

We describe a new genus in the mite family Laelapidae from Slovakia, Ochaechulla gen. nov., to accommodate a new species, Ochaechulla spinturniciformis sp. nov., based on females collected from under loose tree bark that probably served as a bat roost. The new genus is characterized by a specific idiosomal setation with the loss of some setae on the dorsal shield and opisthogastric region, hypotrichy of the legs, an unusual arrangement of the ventral shields and legs on the idiosoma, and strongly shortened peritremes. Its thick dorsal setae, modified body shape, and strong reddish-brown sclerotization most closely resemble the ectoparasites of small mammals in the genus Laelaps C. L. Koch, although its unique combination of features clearly distinguishes it from them and any other dermanyssoids. The radial arrangement of the legs around the margin of the idiosoma is similar to the genus Spinturnix von Heyden.

The genetic diversity of Nipah virus across spatial scales.

Nipah virus (NiV), a highly lethal virus in humans, circulates in Pteropus bats throughout South and Southeast Asia. Difficulty in obtaining viral genomes from bats means we have a poor understanding of NiV diversity. We develop phylogenetic approaches applied to the most comprehensive collection of genomes to date (N=257, 175 from bats, 73 from humans) from six countries over 22 years (1999-2020). We divide the four major NiV sublineages into 15 genetic clusters. Using Approximate Bayesian Computation fit to a spatial signature of viral diversity, we estimate the presence and the average size of genetic clusters per area. We find that, within any bat roost, there are an average of 2.4 co-circulating genetic clusters, rising to 5.5 clusters at areas of 1500-2000km2. We estimate that each genetic cluster occupies an average area of 1.3million km2 (95%CI: 0.6-2.3 million), with 14 clusters in an area of 100,000km2 (95%CI: 6-24). In the few sites in Bangladesh and Cambodia where genomic surveillance has been concentrated, we estimate that most clusters have been identified, but only ∼15% of overall NiV diversity has been uncovered. Our findings are consistent with entrenched co-circulation of distinct lineages, even within roosts, coupled with slow migration over larger spatial scales.

Using spatiotemporal information in weather radar data to detect and track communal roosts

AbstractThe exodus of flying animals from their roosting locations is often visible as expanding ring‐shaped patterns in weather radar data. The NEXRAD network, for example, archives more than 25 years of data across 143 contiguous US radar stations, providing opportunities to study roosting locations and times and the ecosystems of birds and bats. However, access to this information is limited by the cost of manually annotating millions of radar scans. We develop and deploy an AI‐assisted system to annotate roosts in radar data. We build datasets with roost annotations to support the training and evaluation of automated detection models. Roosts are detected, tracked, and incorporated into our developed web‐based interface for human screening to produce research‐grade annotations. We deploy the system to collect swallow and martin roost information from 12 radar stations around the Great Lakes spanning 21 years. After verifying the practical value of the system, we propose to improve the detector by incorporating both spatial and temporal channels from volumetric radar scans. The deployment on Great Lakes radar scans allows accelerated annotation of 15 628 roost signatures in 612 786 radar scans with 183.6 human screening hours, or 1.08 s per radar scan. We estimate that the deployed system reduces human annotation time by ~7×. The temporal detector model improves the average precision at intersection‐over‐union threshold 0.5 (APIoU = .50) by 8% over the previous model (48%→56%), further reducing human screening time by 2.3× in its pilot deployment. These data contain critical information about phenology and population trends of swallows and martins, aerial insectivore species experiencing acute declines, and have enabled novel research. We present error analyses, lay the groundwork for continent‐scale historical investigation about these species, and provide a starting point for automating the detection of other family‐specific phenomena in radar data, such as bat roosts and mayfly hatches.

A simple and fast method for estimating bat roost locations.

Bats play a pivotal role in pest control, pollination and seed dispersal. Despite their ecological significance, locating bat roosts remains a challenging task for ecologists. Traditional field surveys are time-consuming, expensive and may disturb sensitive bat populations. In this article, we combine data from static audio detectors with a bat movement model to facilitate the detection of bat roosts. Crucially, our technique not only provides a point prediction for the most likely location of a bat roost, but because of the algorithm's speed, it can be applied over an entire landscape, resulting in a likelihood map, which provides optimal searching regions. To illustrate the success of the algorithm and highlight limitations, we apply our technique to greater horseshoe bat (Rhinolophus ferrumequinum) acoustic data acquired from six surveys from four different UK locations and over six different times in the year. Furthermore, we investigate what happens to the accuracy of our predictions in the case that the roost is not contained within the area spanned by the detectors. This innovative approach to searching rural environments holds the potential to greatly reduce the labour required for roost finding, and, hence, enhance the conservation efforts of bat populations and their habitats.

Knowledge, perceptions, and exposure to bats in communities living around bat roosts in Bundibugyo district, Uganda: implications for viral haemorrhagic fever prevention and control

BackgroundBats are a reservoir for many viruses causing haemorrhagic fevers. Proximity to bats is a risk factor for virus spillover to animals and humans. We conducted this study to assess knowledge, perceptions, and exposure to bats in communities living near bat roosts in Bundibugyo District, Uganda.MethodsA cross-sectional study using mixed methods with both quantitative and qualitative data was conducted between September and December 2022. Participants for the quantitative data (survey) (n = 384) resided near bat caves and/or roost sites and were selected using multistage random sampling. The survey investigated participants’ prior exposure to bats, as well as knowledge and perceptions of bat exposure. Logistic regression was used to determine factors associated with bat exposure. Participants for the qualitative data (focus group discussions) (n = 10, 6–8 participants each) were purposely selected based on engagement in guano mining, hunting, and farming activities. Perceived risk associated with bat-related activities were identified and ranked in the focus group discussions using participatory epidemiology tools.ResultsIn total, (214/384, 55.7%) had a history of bat exposure and (208/384, 54.2%) had poor knowledge of risk factors associated with bat exposure. Increased exposure to bats was associated with being male (OR = 1.6; 95% CI: 1.0, 2.4 p-value = 0.038), staying in urban areas (OR = 1.9; p-value = 0.010), hunting (OR = 10.9; p-value = 0.024), and positive perception to bat guano being safe as fertiliser (OR = 2.5; p-value = 0.045). During the proportional piling process, a total of 7 risk factors were identified by 10 groups with hunting during an outbreak and consumption of bats being the most frequently identified. Overall, there was a strong statistical agreement in the ranking across the 10 focus groups (W = 0.52; p < 0.01; n = 10). Based on the provided data, the adjusted odds ratio of 0.7 for the good measures (p-value = 0.112), suggests a potential protective effect on the risk of bat exposure.ConclusionCommunities living around bat roosts frequently come into contact with bats, yet there is inadequate awareness regarding the behaviors that can lead to the transmission of bat- borne diseases to humans. It is essential to undertake educational initiatives and preventive measures to minimise the risks of bat-related infections. The need for targeted health communication and education efforts to address these knowledge gaps and promote an accurate understanding of bats and disease transmission. Understanding of diseases associated with bats will minimize bat-related health risks especially in communities engaged in wildlife hunting.

The relative influence of landscape features on maternity roost and hibernaculum selection in temperate bats

Many animal life-history stages center around residences (nests, roosts, etc.) where the availability of resources within an optimal range can affect fitness. Understanding factors influencing residence selection is fundamental for efficient management or recovery plans. Many bat species use permanent roosts during different periods of the year, and while most conservation plans aim to protect these roosts, the availability of suitable habitat near the roosts (e.g., foraging habitat) is also critical to consider. We evaluated the importance of landscape features at multiple scales surrounding seasonal bat roosts in two regions (north and south) of Québec (Canada), using data from participatory science and government databases. In the human-altered environment of south Québec, bats selected maternity roosts with high anthropogenic cover and water edge density at the 150 m and 2 km scales, respectively. Conversely, roost selection in north Québec, a forested area, could not be explained by any landscape features. In winter, fewer bats used hibernacula located in heavily human-modified landscapes—opposite to the trend observed with maternity roost selection. Our study demonstrates how considering landscape features at the appropriate temporal and spatial scales can promote more efficient conservation for bats.

Frequent and intense human-bat interactions occur in buildings of rural Kenya.

Simultaneous use of domestic spaces by humans and wildlife is little understood, despite global ubiquity, and can create an interface for human exposure to wildlife pathogens. Bats are a pervasive synanthropic taxon and are associated with several pathogens that can spill over and cause disease in humans. Urbanization has destroyed much natural bat habitat and, in response, many species increasingly use buildings as roosts. The purpose of this study was to characterize human interactions with bats in shared buildings to assess potential for human exposure to and spillover of bat-borne pathogens. We surveyed 102 people living and working in buildings used as bat roosts in Taita-Taveta county, Kenya between 2021 and 2023. We characterized and quantified the duration, intensity, and frequency of human-bat interactions occurring in this common domestic setting. Survey respondents reported living with bats in buildings year-round, with cohabitation occurring consistently for at least 10 years in 38% of cases. Human contact with bats occurred primarily through direct and indirect routes, including exposure to excrement (90% of respondents), and direct touching of bats (39% of respondents). Indirect contacts most often occurred daily, and direct contacts most often occurred yearly. Domestic animal consumption of bats was also reported (16% of respondents). We demonstrate that shared building use by bats and humans in rural Kenya leads to prolonged, frequent, and sometimes intense interactions between bats and humans, consistent with interfaces that can facilitate exposure to bat pathogens and subsequent spillover. Identifying and understanding the settings and practices that may lead to zoonotic pathogen spillover is of great global importance for developing countermeasures, and this study establishes bat roosts in buildings as such a setting.

Summer habitat for the female Tricolored Bat (Perimyotis subflavus) in Tennessee, United States

Abstract The Tricolored Bat is an imperiled species due to white-nose syndrome. There is limited information available on roosting and foraging area use of the species to support planning and management efforts to benefit recovery in the Southeastern United States. Female tricolored bats exit hibernation and allocate energy toward disease recovery, migration, and reproduction. Providing and managing for summer habitat is 1 strategy to promote recovery. We sought to: (1) determine local- and landscape-scale factors that influence female Tricolored Bat roost selection; (2) quantify land cover use in core and overall foraging areas; and (3) define foraging area size and distances traveled by female tricolored bats in Tennessee. Bats in this study roosted in trees of variable sizes, in multiple tree species with large canopy volumes, and almost always roosted in trees with dead leaf foliage suspended in the canopy. Forest plots used by bats had trees averaging 30 cm diameter at breast height, basal areas averaging 27 m2/ha, contained multiple tree species, and comprised around a 50:50 ratio of canopy and subcanopy trees. Bats did not roost in coniferous forest areas and were only located in deciduous and mixed forest areas. Bats foraged near and directly over water, in open areas, and along forest edges. This study increases our knowledge on habitat requirements of the species in a temperate region dominated by unfragmented forests and many large water bodies and serves a baseline for management and efforts to benefit survival, reproduction, and population recovery.

Behavioral responses of cave-roosting bats to artificial light of different spectra and intensities: Implications for lighting management strategy

Artificial light at night has become an emerging environmental pollutant, posing a serious threat to biodiversity. Cave-roosting animals are vulnerable to light pollution due to long-term adaptation to nocturnal niches, and the problem is especially severe in the context of cave tourism and limestone mining. Mitigating the adverse impacts of artificial light on cave-dwelling animals presents a challenge. This study aimed to assess the relative contributions of spectral parameters and light intensity to the emergence behavior of nine cave-roosting bat species: Rhinolophus macrotis, Rhinolophus pearsonii, Rhinolophus rex, Rhinolophus pusillus, Rhinolophus siamensis, Rhinolophus sinicus, Hipposideros armiger, Myotis davidii, and Miniopterus fuliginosus. We manipulated light spectra and intensities through light-emitting diode (LED) lighting and gel filters at the entrance of bat roost. We monitored nightly passes per species to quantify bat emergence under the dark control and ten lighting conditions (blue, green, yellow, red, and white light at high and low intensities) using ultrasonic recording. Our analyses showed that the number of bat passes tended to be reduced in the presence of white, green, and yellow light, independent of light intensity. In contrast, the number of bat passes showed no pronounced differences under the dark control, blue light, and red light. The number of bat passes was primarily affected by LED light's blue component, red component, peak wavelength, and half-width instead of light intensity. These results demonstrate that spectral parameters of LED light can significantly affect emergence behavior of cave-dwelling bats. Our findings highlight the importance of manipulating light colors to reduce the negative impacts of light pollution on cave-roosting bats as a function of their spectral sensitivity. We recommend the use of gel filters to manage existing artificial lighting systems at the entrance of bat-inhabited caves.

Bat droppings collection by ants in epigean environments

Abstract Ants can be found in insect communities associated with droppings, but most studies about this interaction have been carried out in subterranean environments, specifically in the study of the interaction between ants and bat guano. In this report, we describe the first case of interaction between seven different ant species and the droppings of two bat species in epigean environments. The study was performed in bat roosts monitored from March to October 2022 in the Doñana Biological Reserve of the Doñana National Park (Huelva, SW Spain). It was carried out via direct observations of droppings deposited on the ground surface or in tree‐mounted dropping collectors below bat boxes. We report a total of 37 interactions by seven different species of ants with droppings of two species of bat, the soprano pipistrelle (Pipistrellus pygmaeus) and the greater noctule (Nyctalus lasiopterus), in four different habitats (Eucalyptus camaldulensis, Pinus pinea, Populus alba and ground surface). The generalist characters and the omnivorous diets of the ant species observed, in addition to the abundant availability of droppings during a period of food scarcity, suggest that droppings are transported as a food resource, with the consequent implications that this interaction may have on faecal degradation and nutrient cycling, as one of the supporting services provided by ants.

Presence of coronaviruses in the common pipistrelle (P. pipistrellus) and Nathusius´ pipistrelle (P. nathusii) in relation to landscape composition.

Changes in land use can modify habitat and roosting behaviour of bats, and therefore the transmission dynamics of viruses. Within bat roosts the density and contact rate among individuals increase and may facilitate the transmission of bat coronaviruses (CoVs). Landscape components supporting larger bat populations may thus lead to higher CoVs prevalence, as the number of roosts and/or roost size are likely to be higher. Hence, relationships between landscape composition and the presence of CoVs are expected to exist. To increase our understanding of the spread and shedding of coronaviruses in bat populations we studied the relationships between landscape composition and CoVs prevalence in the species Pipistrellus pipistrellus and Pipistrellus nathusii. Faecal samples were collected across The Netherlands, and were screened to detect the presence of CoV RNA. Coordinates were recorded for all faecal samples, so that landscape attributes could be quantified. Using a backward selection procedure on the basis of AIC, the landscape variables that best explained the presence of CoVs were selected in the final model. Results suggested that relationships between landscape composition and CoVs were likely associated with optimal foraging opportunities in both species, e.g. nearby water in P. nathusii or in areas with more grassland situated far away from forests for P. pipistrellus. Surprisingly, we found no positive association between built-up cover (where roosts are frequently found) and the presence of bat-CoVs for both species. We also show that samples collected from large bat roosts, such as maternity colonies, substantially increased the probability of finding CoVs in P. pipistrellus. Interestingly, while maternity colonies of P. nathusii are rarely present in The Netherlands, CoVs prevalence was similar in both species, suggesting that other mechanisms besides roost size, participate in the transmission of bat-CoVs. We encourage further studies to quantify bat roosts and colony networks over the different landscape compositions to better understand the ecological mechanisms involved in the transmission of bat-CoVs.

Incorporating environmental heterogeneity and observation effort to predict host distribution and viral spillover from a bat reservoir.

Predicting the spatial occurrence of wildlife is a major challenge for ecology and management. In Latin America, limited knowledge of the number and locations of vampire bat roosts precludes informed allocation of measures intended to prevent rabies spillover to humans and livestock. We inferred the spatial distribution of vampire bat roosts while accounting for observation effort and environmental effects by fitting a log Gaussian Cox process model to the locations of 563 roosts in three regions of Peru. Our model explained 45% of the variance in the observed roost distribution and identified environmental drivers of roost establishment. When correcting for uneven observation effort, our model estimated a total of 2340 roosts, indicating that undetected roosts (76%) exceed known roosts (24%) by threefold. Predicted hotspots of undetected roosts in rabies-free areas revealed high-risk areas for future viral incursions. Using the predicted roost distribution to inform a spatial model of rabies spillover to livestock identified areas with disproportionate underreporting and indicated a higher rabies burden than previously recognized. We provide a transferrable approach to infer the distribution of a mostly unobserved bat reservoir that can inform strategies to prevent the re-emergence of an important zoonosis.