Small-footed Myotis Research Articles

Fungal and bat diversities along a landscape gradient in central Mexico.

Species interactions between bats and fungi are poorly known. We documented the association between fungal and bat diversities along a landscape gradient. Ten, eight, and seven bat species were captured in conserved, semi-conserved, and urban sites, respectively. Eptesicus fuscus, Myotis ciliolabrum and Corynorhinus townsendii were the most abundant in conserved and semi-conserved sites. E. fuscus, Myotis velifer, and Lasiurus cinereus were abundant in urban sites. C. townsendii was the least abundant bat. A total of 15 cultivated fungi genera included the fungal diversity in bats, of which nine fungi genera were shared along the landscape gradient. Penicillium and Aspergillus were the most abundant genera, and Aureobasidium, Bispora, Stachybotrys, and Verticillium were only documented in the conserved sites. We observed a higher fungal diversity associated with bat species along this landscape gradient. The individual site-based accumulation curves of fungal diversity showed significant decreasing values along the conserved, semi-conserved, and urban sites, respectively. In conserved and urban sites, M. californicus and M. velifer showed the highest fungal diversity, respectively. E. fuscus was associated to the fungi genera Scopulariopsis, Alternaria, Penicillium and Beauveria; L. cinereus to Cladosporium and Aspergillus, and M. velifer to Alternaria sp1, Bispora and Trichoderma. Conserved sites showed both high bat and fungal diversities [species richness and abundance] compared to semi-conserved and urban sites. More studies associating bat and fungal diversities in other ecosystems are needed to corroborate this pattern.

Diet of Myotis ciliolabrum from Six Sites in the Southwestern United States

Diet of Myotis ciliolabrum from Six Sites in the Southwestern United States

Disturbance of hibernating bats due to researchers entering caves to conduct hibernacula surveys

Estimating population changes of bats is important for their conservation. Population estimates of hibernating bats are often calculated by researchers entering hibernacula to count bats; however, the disturbance caused by these surveys can cause bats to arouse unnaturally, fly, and lose body mass. We conducted 17 hibernacula surveys in 9 caves from 2013 to 2018 and used acoustic detectors to document cave-exiting bats the night following our surveys. We predicted that cave-exiting flights (i.e., bats flying out and then back into caves) of Townsend’s big-eared bats (Corynorhinus townsendii) and western small-footed myotis (Myotis ciliolabrum) would be higher the night following hibernacula surveys than on nights following no surveys. Those two species, however, did not fly out of caves more than predicted the night following 82% of surveys. Nonetheless, the activity of bats flying out of caves following surveys was related to a disturbance factor (i.e., number of researchers × total time in a cave). We produced a parsimonious model for predicting the probability of Townsend’s big-eared bats flying out of caves as a function of disturbance factor and ambient temperature. That model can be used to help biologists plan for the number of researchers, and the length of time those individuals are in a cave to minimize disturbing bats.

New record of Myotis ciliolabrum (Merriam, 1886) (Mammalia, Chiroptera) from the State of Mexico, Mexico

Myotis ciliolabrum (Merriam, 1886) is an insectivorous bat of the family Vespertilionidae and has a wide distribution from British Columbia, Alberta, and Saskatchewan in Canada, most of the western and central United States of America to central Mexico. In this study, we report one of the southernmost records from State of Mexico, based on two females collected in 1980 and stored in the Mammals Collection of the Universidad Autonóma Metropolitana. These records increases the knowledge on the distribution of this rare bat in Mexico.

Can acoustic recordings of cave-exiting bats in winter estimate bat abundance in hibernacula?

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.

ROOST CHARACTERISTICS OF BATS IN THE PINE RIDGE REGION OF NEBRASKA

Protecting day roosts is imperative to the persistence and survival of local populations of tree-roosting bats. The Pine Ridge region of Nebraska represents the largest area of coniferous forests in the state and possesses the greatest diversity of bats in Nebraska. In this study, we examined roost characteristics primarily for 4 species in need of conservation in the region: Fringed Myotis (Myotis thysanodes), Long-legged Myotis (Myotis volans), Little Brown Myotis (Myotis lucifugus), and Hoary Bat (Aeorestes cinereus). With a limited understanding of roost characteristics for other species in the region, we also collected some roost data for the Big Brown Bat (Eptesicus fuscus) and Western Small-footed Myotis (Myotis ciliolabrum). We tracked 42 bats with an emphasis on lactating females. Fringed Myotis, Big Brown Bats, and Western Small-footed Myotis typically roosted in cracks and crevices of dead trees. Long-legged Myotis roosted only in rock crevices at our western-most study site and only large, dead Ponderosa Pines (Pinus ponderosa) at our eastern-most site. Little Brown Myotis roosted in human-made structures in large colonies. Hoary Bats roosted in foliage of live hardwoods and conifers. Conservation of dead Ponderosa Pines, particularly those with large diameters and exfoliating bark, will provide roost structures for most crevice-roosting bats in the region. Our limited data for Hoary Bats suggest that roost-tree use is variable, as individuals roosted in both live hardwoods and conifers. Exclusive use of buildings throughout the region by female Little Brown Myotis implies timber harvests and wildfires might not greatly affect roosts for reproductive females. We demonstrated that roost characteristics vary among species and between nearby populations of the same species, representing important information for making informed habitat management decisions in a region with limited forests in northwestern Nebraska.

Do black‐tailed prairie dog (Cynomys ludovicianus) colonies attract foraging bats?

AbstractBlack‐tailed prairie dog (BTPD) colonies are known to be hotbeds of biodiversity. Manipulation of landscape by BTPDs increases plant and animal diversity in grasslands, and thus BTPDs are considered ecosystem engineers. If BTPD colonies induce increases in insect diversity in the eastern foothills of Colorado, as shown for other areas, it stands to reason that insectivorous bats may respond by increasing their activity in those areas. I tested this hypothesis in the north‐eastern foothills habitat of Colorado, USA, by surveying for echolocation calls within four BTPD colonies and adjacent reference sites lacking BTPD burrows. Results show that bats were significantly more active in BTPD colonies than at adjacent reference sites. In addition, of the nine resident bat species, small‐footed myotis (Myotis ciliolabrum) showed the most consistent relationship with BTPD colonies. Other species that were more active in BTPD colonies included little brown myotis (M. lucifugus), fringed myotis (M. thysanodes), big brown bats (Eptesicus fuscus), and hoary bats (Lasiurus cinereus). The typically forest‐edge adapted species, M. ciliolabrum, and M. thysanodes a forest‐adapted specialist, were active more than expected in treeless BTPD colonies indicating the BTPD colonies are providing a resource not present outside colony perimeters. This study provides the first evidence of a relationship between BTPD colonies and bats in western North America.

Seasonal Activity and Diets of Bats at Uranium Mines and Adjacent Areas near the Grand Canyon

Little information exists on the habitat use and feeding ecology of insectivorous bats in arid ecosystems, especially at and near uranium mines in northern Arizona, within the Grand Canyon watershed. In 2015–2016, we conducted mist-netting, nightly acoustic monitoring (>1 year), and diet analyses of bats, as well as insect sampling, at 2 uranium mines (Pinenut and Arizona 1) with water containment ponds. Because of physical barriers and limited general access to areas within the mine yard, mist-netting was limited to outside of the perimeter fence and away from the containment ponds. Mist-netting also occurred at 2 nearby sites that served as proxies to the mines. Bats captured directly at the mines included one pregnant Antrozous pallidus and 3 adult male Parastrellus hesperus. At the proxy sites, we captured 45 individuals identified as A. pallidus, Corynorhinus townsendii, Eptesicus fuscus, Euderma maculatum, Lasionycteris noctivagans, Myotis californicus, Myotis ciliolabrum, P. hesperus, and Tadarida brasiliensis. The nightly and seasonal presence of bats, as shown through acoustic recordings at each mine, coincided with the seasonal migratory and hibernation behaviors of the bat species. Statistical comparisons of acoustic recordings with precipitation data collected over one year show that seasonal monsoon rains generally had a negative effect on the nightly activity and presence of bats. Diets of P. hesperus from both mines were comprised mostly of coleopterans but also included smaller volumes of Hymenoptera, Hemiptera, Lepidoptera, Diptera, and Neuroptera. The diet of A. pallidus was comprised solely of Coleoptera. Diets of bat species from the proxy sites were characteristic of their known feeding ecology, which ranged from the consumption of soft-bodied insects (e.g., moths) by C. townsendii to the consumption of hard-bodied insects (e.g., beetles) by E. fuscus. Ultimately, the increased knowledge of the natural history of bats through multiple methods of data collection allows for a better understanding of complex arid ecosystems. It also provides resources needed for the management of habitat associated with alternative energy, such as uranium mining.

Long-term patterns of cave-exiting activity of hibernating bats in western North America

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.

Potential foraging niche release in insectivorous bat species relatively unaffected by white-nose syndrome?

White-nose syndrome (WNS) has rendered four of Ontario’s species endangered, while leaving the other four species relatively unaffected. The causes and extent of the declines have been widely studied. The influence on remaining bat species has not. Comparing acoustic data recorded ∼10 years apart, we evaluated how species in southeastern Ontario, Canada, use different foraging habitats pre- and post-WNS detection. We observed activity declines in now-endangered species over open fields (small-footed myotis, Myotis leibii (Audubon and Bachman, 1842); little brown bat, Myotis lucifugus (Le Conte, 1831); northern myotis, Myotis septentrionalis (Trouessart, 1897); tricolored bat, Perimyotis subflavus (F. Cuvier, 1832)) and speculate that the reduction of the once most common species (M. lucifugus) may have resulted in other species searching for prey in habitat once dominated by M. lucifugus. That is, these changes may have allowed greater presence in open field and clutter or edge environments by the big brown bat (Eptesicus fuscus (Palisot de Beauvois, 1796)) and three migratory species (silver-haired bat, Lasionycteris noctivagans (Le Conte, 1831); red bat, Lasiurus borealis (Müller, 1776); hoary bat, Lasiurus cinereus (Palisot de Beauvois, 1796)). However, our results also suggest that (i) while the decline of most resident bat species due to WNS may have relaxed competition for relatively unaffected species in some, but not all habitats, that (ii) sensory and biomechanical constraints may limit prey exploitation by these less-affected bat species in these habitats.

Long-term bat abundance in sagebrush steppe

Bats of western North America face many threats, but little is known about current population changes in these mammals. We compiled 283 surveys from 49 hibernacula over 32 years to investigate population changes of Townsend’s big-eared bats (Corynorhinus townsendii townsendii) and western small-footed myotis (Myotis ciliolabrum) in Idaho, USA. This area comprises some of the best bat habitat in the western USA, but is threatened by land-use change. Bats in this area also face invasion by the pathogen causing white-nose syndrome. Little is known about long-term trends of abundance of these two species. In our study, estimated population changes for Townsend’s big-eared bats varied by management area, with relative abundance increasing by 186% and 326% in two management areas, but decreasing 55% in another. For western small-footed myotis, analysis of estimated population trend was complicated by an increase in detection of 141% over winter. After accounting for differences in detection, this species declined region-wide by 63% to winter of 1998–1999. The population fully recovered by 2013–2014, likely because 12 of 23 of its hibernacula were closed to public access from 1994 to 1998. Our data clarify long-term population patterns of two bat species of conservation concern, and provide important baseline understanding of western small-footed myotis prior to the arrival of white-nose syndrome in this area.

Bat Hibernacula in Caves of Southern Idaho: Implications for Monitoring and Management

Bat populations are being impacted by many threats, including white-nose syndrome, wind energy development, and hibernaculum disturbance and modification. Understanding the use of caves as hibernacula by bats in the western United States is necessary for the conservation and management of these mammals and their habitat, as well as for monitoring the arrival of white-nose syndrome. We identified biologically important hibernacula from 304 winter surveys (1 November–31 March) in 64 caves from 1984 to 2016 in southern Idaho, USA. During surveys researchers counted 37,693 bats representing 6 species. Townsend's big-eared bats (Corynorhinus townsendii townsendii) comprised 96.1% (36,237 individuals in 58 caves) and western small-footed myotis (Myotis ciliolabrum ssp.) comprised 3.8% (1432 individuals in 22 caves). Thirty of the 64 caves were biologically important for Townsend's bigeared bats (maximum count ≥20 individuals), and the largest hibernating colony of that species occupied cave C34 (8 surveys, = 1610 individuals, SD 415, range 962–1994). Thirteen caves were biologically important hibernacula for western small-footed myotis (maximum count ≥5 individuals), and the largest hibernating colony of that species occupied cave C24 (6 surveys, = 98 individuals, SD 53, range 32–152). Ten caves were biologically important hibernacula for both species. Our results indicate that Townsend's big-eared bats are the predominant species that hibernate on the Snake River Plain in southern Idaho, and that this area has a high density of hibernacula—and the largest reported hibernaculum—for Townsend's big-eared bats and western small-footed myotis in western North America. We recommend that biologists prioritize monitoring the 13 biologically important hibernacula of western small-footed myotis as well as the 10 caves used by both species for the potential arrival of white-nose syndrome in this area and to track the abundance of Townsend's big-eared bats. Our results will help biologists with the management and conservation of bats and their habitat as well as aid in land use planning in this area.

Documentation of Overwintering Bat Species Presence and Hibernacula Use In the Badlands of North Dakota

Little work has focused on species presence, distributions, and habitat use of bats in the Great Plains of North America. In particular, no previous study has attempted to determine if bats are utilizing hibernacula during the winter months in North Dakota. The current lack of information regarding bat species presence during the winter months in North Dakota can have great conservation implications. Pseudogymnoascus destructans, the fungal pathogen responsible for white-nose syndrome (WNS) in bats across the United States and Canada, has led to great concern for wildlife managers. For many of the areas where WNS is present, information about the presence and location of hibernacula are known, allowing for close monitoring of the spread of the disease. However, some locations within the predicted path of WNS still lack information as to bat species presence during the winter months. Due to mortality rates sometimes reaching upwards of 100% as a result of WNS infection, filling in these information gaps is critical for conservation research. The purpose of this study was to determine if the badlands region of North Dakota supports over-wintering bat communities, document both utilized and potential hibernacula, and develop a Geographic Information Systems model in the program MaxEnt to be used for future studies and wildlife managers. Six species were positively identified in the badlands region of North Dakota during the pre-hibernation and winter hibernation periods: Big Brown Bat (Eptesicus fuscus), Silver-haired Bat (Lasionycteris noctivagans), Little Brown Bat (Myotis lucifugus), Long-eared Myotis (Myotis evotis), Townsend's Big-eared Bat (Corynorhinus townsendii), and Western Small-footed Myotis (Myotis ciliolabrum). Habitat suitability modeling was employed to model potential hibernacula in the study area. Knowledge of these potential hibernacula could be of great importance to wildlife managers, and results from this study may be used by regional wildlife managers to develop strategies for curtailing the spread of this disease into North Dakota.

Patterns of Genetic Divergence amongMyotis californicus,M. ciliolabrum, andM. leibiiBased on Amplified Fragment Length Polymorphism

The California myotis (Myotis californicus) and the western small-footed myotis (Myotis ciliolabrum) are largely sympatric in western North America, and are especially similar morphologically such that only subtle features of their skull distinguish the two species. Previous analysis of mitochondrial DNA (mtDNA) sequence data resulted in paraphyly of these two species. Our objective was to examine genetic differences in nuclear loci between M. californicus and M. ciliolabrum, investigate their relationship with M. leibii, and to address the conflicting morphological and mtDNA data sets. We analyzed 198 amplified fragment length polymorphism (AFLP) fragments from 17 M. californicus, 16 M. ciliolabrum, and 10 M. leibii using principal coordinate (PCoA), neighbor-joining, Bayesian, and parsimony analyses. Our analyses recovered well-supported separation of M. californicus and M. ciliolabrum based on nuclear markers, suggesting the failure of the mitochondrial markers to recover monophyletic lineages was due to a lack of lineage sorting. Unexpectedly, M. ciliolabrum was paraphyletic with respect to M. leibii individuals from the eastern United States. In conclusion, our analysis of nuclear AFLP markers recovered distinct genetic lineages or clusters that corresponded to the recognized species defined by morphology, M. californicus, M. ciliolabrum, and M. leibii. We propose that these divergences are somewhat incomplete and the divergence between M. ciliolabrum and M. leibii occurred more recently than the speciation events separating the currently sympatric species M. californicus and M. ciliolabrum.

Survey of the Bat Fauna, Desert National wildlife Refuge, Nevada

Abstract. We conducted a survey of the bat fauna of Desert National Wildlife Refuge (DNWR) in Nevada during 2008–2014. Our objectives were (1) to determine the species present at DNWR by mist-netting at likely bat drinking areas; (2) to compare the bat fauna at White Spot Spring at DNWR to the fauna documented there in 1962–1967; and (3) to assess the possible importance of artificial water sources to bats on this highly arid landscape in relation to an ongoing drought. We captured 480 bats of 10 species in mist nets over drinking water sources; species identifications are documented by voucher specimens. In order of frequency of capture, species and numbers of individuals captured were as follows: canyon bat (Parastrellus hesperus), 223; combined California myotis and western small-footed myotis (Myotis californicus/M. ciliolabrum), 157; long-legged myotis (Myotis volans), 55; long-eared myotis (Myotis evotis), 12; Townsend's big-eared bat (Corynorhinus townsendii), 12; fringed myotis (Myotis thysanodes)...

Migratory and winter activity of bats in Yellowstone National Park

A substantial body of work exists describing timing of migration and hibernation among bats in eastern North America, but less is known about these events among bats inhabiting the Rocky Mountain region. Yellowstone National Park is a geothermally influenced landscape comprised of diverse habitats, creating the opportunity for unique behaviors to develop among local bat populations. We identified the timing of migration for the local bat community and determined if bats overwinter in Yellowstone. To accomplish this, we radiotracked 7 little brown myotis ( Myotis lucifugus ), 5 western long-eared myotis ( M. evotis ), 4 big brown bats ( Eptesicus fuscus ), 4 silver-haired bats ( Lasionycteris noctivagans ), and 1 western small-footed myotis ( M. ciliolabrum ) from August to September 2010 and September to October 2011. We also used acoustic detectors to record bat activity from November through April 2011–2014 and sampled abundance of nocturnal insects using black-light traps from 2011 to 2012. Although availability of insects declined rapidly during August and afterward, several bat species remained active throughout autumn and winter. Bat activity was recorded during all months, even during periods of extreme cold. Radiotagged big brown bats, little brown myotis, and western small-footed myotis remained active in the study area throughout October, after the 1st snowfall of the season. While data for activity patterns in late autumn and winter prevented an estimation of the onset of hibernation, spring emergence occurred in April despite persistence of winter conditions. These data provide insights into the migration and hibernation strategies of bat populations in the Rocky Mountains and highlight gaps in our understanding of seasonal changes in these species.

Novel Cryptosporidium bat genotypes III and IV in bats from the USA and Czech Republic.

Bats from the families Rhinolophidae (n = 90) and Vespertilionidae (n = 191) in the USA and Czech Republic were screened for the presence of Cryptosporidium by microscopic and molecular analysis of faecal samples collected from rectum of dissected animals and from the ground beneath roosting sites. Cryptosporidium oocysts were not detected in any of the 281 faecal specimens examined using the aniline-carbol-methyl violet staining method. Nested PCR amplification, sequencing and phylogenetic analysis of the small ribosomal subunit rRNA and actin genes were used to identify isolates and infer evolutionary relationships. Cryptosporidium parvum was identified in a western small-footed bat (Myotis ciliolabrum) from the USA and a common pipistrelle bats (Pipistrellus pipistrellus) from the Czech Republic. Two novel genotypes were identified and named Cryptosporidium bat genotype III and IV. Bat genotype III was found in two big brown bats (Eptesicus fuscus) from the USA. Bat genotype IV was detected in two common pipistrelle bats from the Czech Republic.

Three new host species of Plagiorchis micracanthos (Macy, 1931) (Trematodes: Plagorchiidae) among North American bats (Chiroptera: Vespertilionidae)

Summary We report new records of the trematode, Plagiorchis micracanthos from three North American bats. For the first time, the parasite is reported to occur in the hoary bat (Lasiurus cinereus), California myotis (Myotis californicus) and the pallid bat (Antrozous pallidus). The western small-footed bat (Myotis ciliolabrum), little brown bat (M. lucifugus) and the western pipistrelle (Parastellus hesperus) are confirmed as host species. The trematodes were isolated from the small intestines of the host individuals. For the first time, we identified P. micracanthos in bats originating from Canada and Mexico. The results presented here suggest that the trematode P. micracanthos has a much larger host range and geographic distribution than previously recognised. It is likely that further studies will confirm this results and extent both host and geographic ranges even further.

Myotis Ciliolabrum found East of its Known Range

Myotis Ciliolabrum found East of its Known Range

English

The purpose of this study was to determine whether inactive mine features on privately owned lands and lands administered by the Bureau of Land Management (BLM) in Pima County, in southeastern Arizona (the study area), were being used by bats. External pre-screening surveys of 60 inactive mine features were completed in March 2012, and it was determined that 23 of these sites had the potential to provide roosts for bats. Passive external portal acoustic and visual surveys of these 23 features were completed using AnaBat acoustic detectors and infrared trail cameras from May through mid-October 2012. Acoustic survey data were analyzed, and 10 species of bats were identified. Bat species were acoustically detected at all 23 sites but were only visually detected at two sites. Acoustically, bat activity and species richness were highest in the spring and lowest in the fall. The two most common species, canyon bat (Parastrellus hesperus) and Mexican free-tailed bat (Tadarida brasiliensis), accounted for more than 50% of all the survey data. Ten sites accounted for more than 75% of all bat activity. Species richness was highest at two sites, with seven species detected at each site, and was lowest at two sites, where only one or two species were detected. Two species identified as species of concern under the Endangered Species Act (ESA) - western small-footed myotis (Myotis ciliolabrum) and Yuma myotis (M. yumanensis) - were acoustically detected at 15 and three sites, respectively. Two BLM-sensitive species (also identified as species of concern under the ESA) - Townsend's big-eared bat (Corynorhinus townsendii) and cave myotis (M. velifer) - were acoustically detected at 10 sites (seven of which are on BLM lands) and seven sites (three of which are on BLM lands), respectively. Although no bats were detected in any photos or videos, when biologists visually monitored each site, bats occasionally were seen flying in the study area around sunset, but only one bat was seen exiting from an inactive mine site. Townsend's big-eared bats were observed roosting in two adits on BLM-administered lands during the fall. No major bat roosts or no threatened or endangered bat species (e.g., lesser long-nosed bats (Leptonycteris curasoae yerbabuenae)) were detected through these surveys.