Bat Communities Research Articles

Microbial community dynamics in blood, faeces and oral secretions of neotropical bats in Casanare, Colombia

Bats are known reservoirs for a wide range of pathogenic microorganisms, including viruses, bacteria, fungi, helminths, and protozoa, which can be transmitted and infect other zoonotic organisms. Various studies have utilised next-generation sequencing (NGS) to describe the pathogens associated with bats. Although most have characterised microbial communities in specific body fluids, few have analysed the composition and diversity of these microbial communities across different body fluids at the individual level. In this study, we employed two next-generation sequencing techniques: amplicon-based sequencing of the V4 hypervariable region of the 16S- and 18S-rRNA genes and viral metagenomics, to describe the prokaryotic, eukaryotic, and viral communities present in blood, faeces, and oral swab samples collected from two genera of bats (Carollia and Phyllostomus) in the department of Casanare, eastern Colombia. A total of 60 samples corresponding to the three bodily fluids were processed and analysed. The results indicated that the microbial communities across the body fluids were mainly composed of bacteria, fungi, protozoa, and various DNA and RNA viruses, showing a variability of microbial genera and species. The abundances, diversity metrics, and correlations of these microorganisms displayed patterns associated with bat genus and body fluids, suggesting that the ecological characteristics of these microbial communities may be influenced by the ecological and physiological traits of the bats. Additionally, we found similar community compositions of bacteria, some fungal genera, and viruses in the three body fluids, indicating a possible circulation of these microbes within the same bat. This could be due to microbial movement from the gut microbiota to other physiological systems or transmission via blood-feeding vectors. Furthermore, our results revealed the presence of various microbes of public health concern, including Bartonella spp., Mannheimia haemolytica, Rhodotorula spp., Piroplasmida spp., Toxoplasma gondii, Alphacoronavirus spp., and Bat circovirus. The abundance of these pathogenic microbial species across the three bodily fluids suggests potential transmission routes from bats to other organisms, which may contribute to the emergence of zoonotic disease outbreaks. These findings highlight the variability of microorganisms present within the same bat and the different pathogen-host interactions that may regulate the presence and transmission of these zoonotic microbes. Further research is required to elucidate the genomic features, ecological interactions, and biological activities of these microbial communities in bats.

The Influence of Habitat Diversity on Bat Species Richness and Feeding Behavior in Chilean Vineyards: Implications for Agroecological Practices

Agriculture is a leading cause of biodiversity loss, making the transition to sustainable agroecological practices crucial. Insectivorous bats play a crucial role as biological controllers in regard to agricultural crops, serving as important insect predators. The purpose of this study is to assess bat communities in three distinct habitats, namely the interior of a vineyard, native vegetation, and the transitional edge between them, by analyzing the echolocation patterns of different species. Generalized linear mixed models were used to evaluate the influence of landscape characteristics on bat communities and at the species level, allowing the incorporation of variables at different scales (at 10 m, 100 m, and 1000 m radius) from each sampling site. Our results show that edges enhance bat richness, their general activity, and feeding patterns, and are of particular benefit to certain species: Tadarida brasiliensis, Myotis chiloensis, and Lasiurus varius. Implementing agroecological practices, such as the maintenance of tree hedgerows at the landscape scale, along with native vegetation at the landscape scale, can amplify feeding activity in vineyards, thereby enhancing the provision of ecosystem services in agroecosystems. The edges of vineyards and natural vegetation are crucial for providing habitats for bats and increasing their foraging activity, as well as providing a way to enhance agroecological practices in vineyards to bolster ecosystem services.

Is it only the hood, or also the neighbour? Bat occupancy and community drivers in heterogeneous urban landscapes

Is it only the hood, or also the neighbour? Bat occupancy and community drivers in heterogeneous urban landscapes

Anthropogenic disturbances alter the trophic niche structure and ecological relationships of understory bat communities in the Ecuadorian Andean Chocó

Human disturbances have reduced the three basic niche dimensions for the survival of some mammalian species (space, time, and resources). Anthropic activities cause the extinction of ecological functionalities faster than species extinctions. In this study, we identified four types of habitats in the Ecuadorian Andean Chocó: primary forest (PF), secondary forest in natural regeneration (SF1), secondary forest in assisted regeneration (SF2), and pastures for cattle (P). The main objective was to determine the responses in the trophic niche and the ecological relationships of understory phyllostomid bat communities. We captured bats with mist nets and obtained fecal samples from 21 species. These were analyzed to quantify seeds, pollen, insects, and vertebrates consumed by each individual, with counts organized by species and habitat type. We conducted an ecological relationship analysis to understand the structure of bat–fruit networks and their dietary preferences. We calculated niche breadth and niche overlap to understand the trophic niche composition of each species. We applied null models to evaluate if there is evidence of trophic niche partitioning among these species. Despite a relatively small sample size, the results obtained are nevertheless interesting. While niche breadth was not useful for detecting the effects of human disturbances, niche overlap was significantly higher in disturbed habitats (SF1, SF2 and P), where ecological relationships were weaker. Most of the species were related to the consumption of seeds from the genus Piper. These results indicate that bat communities and their ecosystem services may be highly endangered due to anthropogenic disturbances. Network interactions in bats are highly variable in geographic space and time, and little is known about the community structure of bat–seed interactions. Studying mutualistic networks in bats and seeds is crucial because of their role in ecosystem support, supply, and regulation services that depend on them.

Quantification of threats to bats at localized spatial scales for conservation and management.

In a rapidly changing world, where species conservation needs vary by local habitat, concentrated conservation efforts at small spatial scales can be critical. Bats provide an array of value to the ecosystems they inhabit; many bat species are also of conservation concern. San Diego County, California, contains 22 of the 41 bat species that occur in the United States, 16 of which are on conservation watchlists. Thus, management of bat communities in San Diego County is a pressing need. Because bats exploit vast areas of the landscape and historical sampling strategies have shifted over time, a standardized way of prioritizing areas of the landscape for management would provide an integral asset to bat conservation. We leveraged long-term bat community survey data from sampling areas across San Diego County to prioritize areas with the most management need. We calculated two types of scores: species scores and threat scores. Species scores incorporated richness and conservation status, and threat scores included landscape level threats that bats could encounter. We found that urbanization, the presence of artificial lights, and areas sampled on unconserved land were all significantly associated with decreases in species richness. Further, using species and threat scores, each sampling area was placed into one of four conservation categories, in order from greatest to least conservation need, ranging from highest priority (high species score, high threat score) to lowest (low species score, low threat score). Additionally, we focused on sampling areas in which Townsend's big-eared bat (Corynorhinus townsendii) and/or pallid bat (Antrozous pallidus) occurred. These two species are of exceptional conservation concern in San Diego County and across the western United States. We identified urbanization, the presence of artificial lights, and areas sampled on unconserved land as threats that were all significantly associated with the absence of Townsend's big-eared bat, but not pallid bat. The strategy, methodology, and solutions proposed in our study should assist bat conservation and management efforts wherever bats occur, and can be extended to other species that require conservation attention.

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.

The role of landscape context in shaping bat assemblages in African cacao plantations

Cacao production is mostly concentrated in Africa, with this continent exporting an impressive 68.4 % of the world's cacao. The increasing demand for cacao from the Global North has already led to massive deforestation in Ghana and Ivory Coast and cacao-driven deforestation is likely to continue changing landscapes in Sub-Saharan Africa. Bats are affected by these landscape changes due to their dependence on multiple resources spread at a large spatial scale. Although bats can save cacao farmers millions of euros through pest suppression, no study has investigated how landscape context affects bat communities in African cacao plantations. Here for the first time, we studied how abundance and richness of insectivorous, frugivorous and nectarivorous bats within cacao landscapes could be affected by cover type and the distance between these habitats and each cacao plantation. We sampled bats using mist-nets in 38 cacao plantations spread throughout southern Cameroon from 2017 to 2020. We found that guilds responded differently to the distance and amount of cover of each of the land cover types, with the scale of response being habitat-dependent. Overall, insectivorous bats were associated positively with high cover of natural habitats (e.g., tree cover, rangeland, and flooded vegetation), and negatively with nearby anthropogenic disturbance (e.g., logging and intensive agriculture). Frugivorous and nectarivorous bats were associated to the presence of natural habitats with water and of nearby anthropogenic habitats (e.g., human settlements, community forests and unpaved roads), probably due to the presence of more fruiting and flowering trees. Considering the associations found between the landscape metrics and bats, we propose three different conceptual designs to manage cacao landscapes: one for insectivores, one for frugivores/nectarivores and a third design that maximises the trade-offs between these three guilds. By safeguarding the diversity of these three guilds farmers can maintain pest suppression services within their plantations and guarantee healthy and long-lasting sustainable cacao landscapes through bats' pollination and seed dispersal.

Taxonomic, Functional, and Phylogenetic Diversity of Bats in Urban and Suburban Environments in Southern México

Urbanization is one of the leading causes of habitat loss, which has increased significantly in tropical regions in recent years, leading to the loss of species, their ecological functions, and evolutionary history. To determine the effect of urbanization on the diversity of bat communities in urban and suburban environments, we analyzed the α and β taxonomic, functional, and phylogenetic diversities at four sites along urbanization gradients surrounding a rapidly expanding city (Oaxaca City) in southern Mexico. We recorded bats using conventional techniques such as mist nets and acoustic monitoring. We calculated the diversity of bats in four sites with different urbanization conditions: urban (1), suburban (1), and rural (2). To assess the degree of total differentiation and components of bat turnover and nestedness between sites, we calculated the β taxonomic, functional, and phylogenetic diversities. A total of 33 bat species were recorded. The highest taxonomic and functional diversity was observed in the Center of Oaxaca (the site with the highest level of urbanization). In contrast, the highest phylogenetic diversity was found in the West (the site with the lowest level of urbanization). The total β taxonomic diversity was higher than the functional and phylogenetic diversity. Regarding the contributions of turnover and nestedness, turnover made a more significant contribution than nestedness to the taxonomic and phylogenetic β diversity. In contrast, functional nestedness contributed more to the functional β diversity than turnover. Tadarida brasiliensis, Desmodus rotundus, Sturnira hondurensis, and S. parvidens were recorded in all three urbanization conditions. In the most urbanized site, four Myotis species were recorded: M. fortidens, M. keaysi, M. thysanodes, and M. velifer. We suggest that the analysis of different dimensions of diversity is essential and should be considered to strengthen conservation strategies; moreover, we suggest the preservation of native vegetation mosaics and water bodies within the city to maintain bat diversity.

Buzzfindr: Automating the detection of feeding buzzes in bat echolocation recordings.

Quantification of bat communities and habitat heavily rely on non-invasive acoustic bat surveys the scope of which has greatly amplified with advances in remote monitoring technologies. Despite the unprecedented amount of acoustic data being collected, analysis of these data is often limited to simple species classification which provides little information on habitat function. Feeding buzzes, the rapid sequences of echolocation pulses emitted by bats during the terminal phase of prey capture, have historically been used to evaluate foraging habitat quality. Automated identification of feeding buzzes in recordings could benefit conservation by helping identify critical foraging habitat. I tested if detection of feeding buzzes in recordings could be automated with bat recordings from Ontario, Canada. Data were obtained using three different recording devices. The signal detection method involved sequentially scanning narrow frequency bands with the "Bioacoustics" R package signal detection algorithm, and extracting temporal and signal strength parameters from detections. Buzzes were best characterized by the standard deviation of the time between consecutive pulses, the average pulse duration, and the average pulse signal-to-noise ratio. Classification accuracy was highest with artificial neural networks and random forest algorithms. I compared each model's receiver operating characteristic curves and random forest provided better control over the false-positive rate so it was retained as the final model. When tested on a new dataset, buzzfindr's overall accuracy was 93.4% (95% CI: 91.5%- 94.9%). Overall accuracy was not affected by recording device type or species frequency group. Automated detection of feeding buzzes will facilitate their integration in the analytical workflow of acoustic bat studies to improve inferences on habitat use and quality.

Traits and trails: Guild-specific effects of forest paths on bat activity

Human activities can substantially alter forest structure, consequently affecting forest animal communities. An important effect on bat behavior is given by canopy discontinuities like clearings or trails: while the former act as foraging sites, the latter are known to be used by bats to move inside the forest. For this reason, we can expect trails to have a strong influence on bat activity, with differences determined by the species' flying abilities. Here we assess the impact of trails on a local bat community by quantifying the effect of trails’ characteristics on the activity of bat species in relation to their wing morphology. We collected paired acoustic data and environmental variables along trails and in internal areas of a forest in central Italy. We modelled the activity levels of three bat guilds differing in wing morphology and identified the species mostly responsible for the observed compositional dissimilarity in between trails and internal zones by adopting a multivariate approach. Trail width and tree’s diameter were the main drivers of the observed differences between bat activity along trails and internal areas, but their effect differed among bat guilds. Edge and open-space foragers increased their activity along wider trails, while closed-space foragers showed an opposite trend; the latter also avoid trails in favor of internal areas especially when trees are larger. Four species yielded a significant contribution to the dissimilarity in activity levels between trails and internal areas, and namely Pipistrellus pipistrellus, Nyctalus noctula, Miniopterus schreibersii and Barbastella barbastellus. Our results show a clear effect of forest trails on bat activity, highlighting differences across functional groups in relation to trail characteristics. Furthermore, within guilds, not all species respond with the same intensity, suggesting differences in how different species are attracted to linear features and forest gaps. Overall, our results depict a complex interaction between forest trails and bat activity, suggesting that structural changes in forests can trigger diverse responses in bats. Future research on the topic may focus on assessing how such effects can affect bat communities at the landscape scale and longer time-scales.

Summer chiropteran community in the Sergievka Park with the unique dominance of Pipistrellus nathusii on the northern periphery of its distribution range

The study of species on the periphery of their ranges is especially relevant for long-term research in protected areas. The aim of this study is to test the hypothesis that Pipistrellus nathusii on the northern periphery of its range has a clumped distribution with long-term viable breeding centres. The species composition and relative abundance of bats in the park were determined through capturing them with mist nets during the 1997–1998 and 2020–2022 survey periods. Within the 2nd survey period the use of an ultrasonic detector was additionally involved. Stability of the bat species composition in the protected area and a significant difference in the relative abundance between the surveys were revealed (χ2 = 47.31, p < 0.05). During both periods, the bat community in the park exhibited a pronounced dominance of P. nathusii and stable values of its relative abundance (40.7 and 44.2%, respectively). Perennial nursery colonies of Myotis daubentonii, Nyctalus noctula, and P. nathusii have been discovered in the park, which are arguably among the northernmost findings (59.89° N, 29.88° E) in European Russia. The catch rate (6.3 bats per net-night) and acoustic activity of the Chiroptera (16.6 active minutes per detector-hour) on the pond was significantly higher than on the alley and glade. This pattern is typical for all frequently recorded bat species – P. nathusii, N. noctula and Eptesicus nilssonii. According to the results of multiple analysis of variance, the effect of species on acoustic activity was the greatest (η = 24.59%, F = 15.52, p < 0.001). The impact of the habitat and the time since sunset, as well as the pairwise combined impact of these three factors, was also significant and reliable. The sizes of the nursery colonies were determined, which in P. nathusii were record high for the northern periphery of the breeding range, 212 individuals. Evening departures of P. nathusii from the nursery colony on the alley were characterized by their beginning before sunset, and from the nursery colony in the glade after sunset. The intensity of P. nathusii departure from the colony in the forest part of the park is significantly higher (5.3 bats/ min) than in the glade (1.4 bats/min). The fact that large nursery colonies of P. nathusii have existed for decades locally at 60° N latitude suggests the species may have a wider distribution in Eastern Fennoscandia in transformed areas containing old trees. Keywords: bats; South-Eastern Fennoscandia; relative abundance; nursery colonies; acoustic activity; circadian rhythms

Island area and diet predict diversity and distribution of bats in a Pacific Northwest archipelago

Abstract The island biogeography theory predicts that species richness in islands and island-like systems is the ultimate result of island isolation and area. Species with high dispersal capabilities are predicted to be less affected by these factors because of their capacity to move more efficiently between islands or habitats, and here we test this idea in bats, the only mammals capable of flight. We conducted mist net and acoustic surveys across 21 islands in the San Juan Archipelago (Washington State, United States) and adjacent northwest mainland to: (i) investigate the effects of island area, distance from mainland, and habitat on bat diversity; and (ii) evaluate whether differences in morphological (body mass, forearm length, wing loading) and ecological (dietary niche breadth, foraging guild) traits among species influence their prevalence across islands. We found that island size strongly influenced patterns of species richness, with larger islands having a greater number of bat species. However, neither island distance from mainland nor any measure of habitat availability was a significant predictor of species richness at the scale of this study. Additionally, we found that dietary niche breadth, as opposed to any morphological trait, best predicted the prevalence of species across the islands. Our results suggest that species with more specialized diets may be more vulnerable to habitat fragmentation, and provide insight into how geographic and ecological factors affect the diversity of insular bat communities, adding to growing knowledge about the role of species traits as mediators of their responses to large-scale landscape structure.

Between Wires and Wings: What Are the Impacts of Power Transmission Lines on the Diversity of Insectivorous Bats?

Energy consumption in the world is growing every year, and there is an increasing demand on the energy system to meet the increase in consumption, resulting in the installation of new power transmission lines. The understanding of how power transmission lines affect biodiversity is predominantly focused on birds, with limited information available on other organisms. In this study, we assessed the potential effect of power transmission lines on bat communities in a locality in the Cerrado biome in Brazil. More specifically, we used a paired sample design and acoustically sampled bats in locations near and far from the transmission lines. Our findings suggest that power transmission lines do not have a generally positive or negative effect on insectivorous bat communities in the study area. However, their presence seems to be associated with increased diversity in specific functional groups and changes in the activity patterns of some bat species and families. We believe that this information is of particular importance for establishing appropriate programs during the environmental licensing process, assisting in the development of projects in the different stages of construction as well as in monitoring programs during operation.

Bat community structure in urban green areas of northeastern Brazil

Bat community structure in urban green areas of northeastern Brazil

Designing Decentralized Systems with High Survivability Inspired by Altruistic Social Interactions of Vampire Bats

Altruism is a key concept in the design of decentralized systems with high survivability. We focus on a community of vampire bats to reveal how intra-group altruism produces group-wide survivability. Although these bats die within three days if food is unavailable, they can survive for over 10 years by developing a highly sophisticated social community in which they share food. This food-sharing behavior occurs not only among blood relatives, but also among unrelated individuals through self-organizing social relationships based on grooming behavior. We propose a simple network model that focuses on the relationship between food sharing and grooming. We performed simulations under periodic, stationary, and irregular feeding environments, and found that suitable update rules for social relationships depend on the type of environment. Our findings provide insights into how decentralized systems with high survivability can be designed based on altruism.

Species composition, abundance and spatial structure of bat community hibernating in Tanechkina and Staroladozhskaya Caves, Leningrad Region, Russia

Species composition, abundance and spatial structure of bat community hibernating in Tanechkina and Staroladozhskaya Caves, Leningrad Region, Russia

Listening to the response of bat and bush‐cricket communities to management regimes of powerline clearings

AbstractLinear transportation infrastructures (LTIs) are established drivers of habitat fragmentation and barrier effects. Yet, they represent an increasing surface of managed seminatural habitats where increased consideration of biodiversity outputs is needed in an era of global biodiversity decline. A combined effort by both scientists and stakeholders is, therefore, needed to evaluate the promises and limits of these alternatives so that they best achieve their conservation potential. Our study explores the effects of forest powerline clearings on biodiversity, as well as the potential benefits of integrated vegetation management (IVM) as alternatives to clear‐cuts. We recorded the acoustic activity at 35 pairs of forest/clearing stations in two forested regions of France in 2021. Our results suggest that powerline clearings represent increased movement opportunities for bats and, most particularly, edge‐foraging species. They also provide suitable habitats for bush‐cricket species, particularly species requiring thermophilic conditions. We detected no direct benefit from IVM on bat communities. However, bush‐cricket communities appeared richer, more acoustically active, and statistically different from adjacent forests in clearings favoring secondary vegetation compared with clear‐cut ones. This collaborative study provides data on understudied taxa in the context of LTIs and sheds light on conservation promises and limits associated with their management.

Unexpected bat community changes along an urban–rural gradient in the Berlin–Brandenburg metropolitan area

Urbanization gradients are increasingly used in ecological studies to discover responses of species communities to different intensities of human-induced habitat transformation. Here, we investigated patterns of bat communities against the background of different urbanization levels using a priori defined urbanization categories based on distance classes (5 km intervals) along a linear transect from the urban core of the city of Berlin westwards into the rural outskirts of the state of Brandenburg. Using linear-mixed effects models, we found that “distance class”, as a proxy for urbanization level, is a meaningful and suitable predictor of bat species richness and diversity. We observed an unexpectedly sudden increase in bat species richness and diversity and changes in species-specific activity levels relatively close to the urban center at the transition between urban and peri-urban areas. This change suggests a relevant influence of the peri-urban areas as a “buffer zone” for specific bat species not able to adapt to the heavily modified inner core of the metropolitan area. Although we could demonstrate that anthropogenic noise and artificial light have the potential to predict the variability of bat species activity along the urban–rural gradient, the actual influence on observed shifts in the bat community needs further research.

Deep biogeographic barriers explain divergent global vertebrate communities

Biogeographic history can lead to variation in biodiversity across regions, but it remains unclear how the degree of biogeographic isolation among communities may lead to differences in biodiversity. Biogeographic analyses generally treat regions as discrete units, but species assemblages differ in how much biogeographic history they share, just as species differ in how much evolutionary history they share. Here, we use a continuous measure of biogeographic distance, phylobetadiversity, to analyze the influence of biogeographic isolation on the taxonomic and functional diversity of global mammal and bird assemblages. On average, biodiversity is better predicted by environment than by isolation, especially for birds. However, mammals in deeply isolated regions are strongly influenced by isolation; mammal assemblages in Australia and Madagascar, for example, are much less diverse than predicted by environment alone and contain unique combinations of functional traits compared to other regions. Neotropical bat assemblages are far more functionally diverse than Paleotropical assemblages, reflecting the different trajectories of bat communities that have developed in isolation over tens of millions of years. Our results elucidate how long-lasting biogeographic barriers can lead to divergent diversity patterns, against the backdrop of environmental determinism that predominantly structures diversity across most of the world.

Flying by the river side: Survey of bat distributions and environmental contexts along a 1000‐mile river corridor, Green and Colorado Rivers, USA

AbstractAimEmerging research shows how bioindicators, specifically bats, can serve as a means for monitoring conservation and management of riparian corridors for multiple taxonomic groups. To track changes in the composition or abundance of bioindicator species, researchers must attain a baseline in species presence and relative activity. We examined the spatial and temporal patterns of bat community composition and activity along a 1000‐mile river corridor to determine species diversity trends by latitude and habitat.LocationColorado River Basin.MethodsHere we describe the results from an acoustic bat survey conducted opportunistically on the 2019 Sesquicentennial Colorado River Exploring Expedition. This broad, 1000‐mile survey provides a baseline for species distributions over a large geographic range.ResultsIn total, we collected 63 nights of acoustic data over 70 days and recorded over 59,000 files equating to 45,363 caLL files (≥2 pulses). 18,490 (41% of caLL files) were identified as species (n = 19 bat species). We applied non‐metric multidimensional scaling to characterize spatiotemporal patterns of activity between species, as well as compared bat activity among river features and local environmental conditions (i.e., temperature and time since sunset) using an information theoretic approach.ConclusionSpecies composition varied by physiographic region and adjacent river habitat, thus providing a quantifiable measure of determining habitat quality along this major river system and providing baseline information for using bats as bioindicators of habitat quality.