Perimyotis Research Articles

Geographic Distribution, Reproduction, and Seasonal Activity of Bats in Iowa

From 2002 to 2018, we conducted 525 events to survey bats (nights of mist-netting and visits to bridges, mines, caves, etc.) and captured or observed 6119 bats, including all 9 species that regularly reside in Iowa. Our captures include a total of 142 new county records, and we located an additional 11 county records in specimens deposited in museums; we present at least 8 county records for each species in the state. Since the geographic distributions of most species span the entire state, many of these county records simply fill in gaps within hypothesized distributions. Records for Lasionycteris noctivagans, Lasiurus borealis, Myotis lucifugus, Myotis septentrionalis, Myotis sodalis, Nycticeius humeralis, and Perimyotis subflavus, however, extend the known range for these species or fill large gaps in their suspected distribution. Additionally, our captures provide evidence of reproduction occurring across the state for most species. Previously, little information had been published on the geographic extent of reproduction for bats in Iowa. Lastly, we report new information regarding timing of seasonal activities for bats in Iowa. For most species, we present new early and/or late records for lactation, postlactation, appearance of flying young, and flight activity outside of hibernation. Collectively, these records expand our knowledge of the biology of bats in Iowa.

Survival and persistence of tricolored bats hibernating in Arkansas mines

AbstractWhite-nose syndrome (WNS) has caused large declines in bat populations across eastern North America, making information on demographics of affected species critical to determining their risk for extinction. We used Cormack–Jolly–Seber models to estimate apparent survival rates of hibernating tricolored bats (Perimyotis subflavus) for 5 years in four small abandoned mines in the Ouachita Mountains of Arkansas, located within the WNS endemic area of the United States. Populations in individual mines varied greatly in survival rates, with one mine displaying annual survival rates as high as 0.706 and another as low as 0.101. Differences in survival among bats in different mines could not definitively be attributed to WNS, but may have varied based on a combination of WNS, disturbance, mine climate, and other unknown factors. Further, some hibernacula may have served as temporary winter shelter for young transient males. Sites housing small colonies of hibernating bats may result in high survival rates despite WNS, and protecting these smaller sites may be important for overall species perseverance.

Systematic Review of the Roost-Site Characteristics of North American Forest Bats: Implications for Conservation

Continued declines in North American bat populations can be largely attributed to habitat loss, disease, and wind turbines. These declines can be partially mitigated through actions that boost reproductive success; therefore, management aimed at promoting availability of high-quality roosting habitat is an important conservation goal. Following the principles of the umbrella species concept, if co-occurring species share similar roost-tree preferences, then management practices targeting one species may confer conservation benefits to another. We conducted a systematic review of roost-site characteristics of thirteen species inhabiting eastern temperate forests to: (1) synthesize existing knowledge across species; (2) assess niche overlap among co-occurring species; and (3) evaluate the potential for currently protected species to serve as conservation umbrellas. We performed multivariate ordination techniques to group species based on the seven most-reported roost-site characteristics, including tree species, diameter at breast height, tree health, roost type, tree height, canopy closure, and roost height. Species sorted into three roosting guilds: (1) southern wetland inhabitants; (2) foliage specialists; and (3) dead tree generalists. Myotis septentrionalis and Perimyotis subflavus had significant roost-niche overlap with five and four other species respectively, and their existing protections make them suitable umbrellas for other bats in the North American eastern temperate forests.

Species specific effects of prescribed burns on bat occupancy in northwest Arkansas

Due to the recent spread of white nose syndrome, it is imperative that managers understand the effects their management techniques have on bat species. Our research aims to determine the spatial and temporal variation in occupancy of bat species native to the Ozark Highlands and Boston Mountains of northwest Arkansas. Although prescribed burn units in this region are burned on a three-year rotation, it is not currently known how this treatment schedule affects bats. To determine the effects of prescribed burns on bat species including Myotis grisescens, Nycticeius humeralis, and Perimyotis subflavus, acoustic monitors and insect traps were deployed at 20 burned and 20 unburned sites that were visited twice, between April and November of 2017. Bat calls were analyzed for presence/absence data. Single season occupancy modeling was used to determine the effects of environmental covariates on probabilities of detection and occupancy. In total, 132,528 acoustic files were collected. The probability of detection for each bat species was affected by temperature or moon phase. Occupancy models indicated that probability of occupancy for all species was affected by seasonal changes and basal area (m2/Ha), and all but one were affected by prey biomass. These data indicate that although prescribed burns may have not directly affected bats, potential indirect effects of fire, basal area and insect biomass, appear to have significant impacts.

External temperature and distance from nearest entrance influence microclimates of cave and culvert-roosting tri-colored bats (Perimyotis subflavus).

Many North American bat species hibernate in both natural and artificial roosts. Although hibernacula can have high internal climate stability, they still retain spatial variability in their thermal regimes, resulting in various “microclimates” throughout the roost that differ in their characteristics (e.g., temperature and air moisture). These microclimate components can be influenced by factors such as the number of entrances, the depth of the roost, and distance to the nearest entrance of the roost. Tri‐colored bats are commonly found roosting in caves in winter, but they can also be found roosting in large numbers in culverts, providing the unique opportunity to investigate factors influencing microclimates of bats in both natural and artificial roost sites. As tri‐colored bats are currently under consideration for federal listing, information of this type could be useful in aiding in the conservation and management of this species through a better understanding of what factors affect the microclimate near roosting bats. We collected data on microclimate temperature and microclimate actual water vapor pressure (AWVP) from a total of 760 overwintering tri‐colored bats at 18 caves and 44 culverts. Using linear mixed models analysis, we found that variation in bat microclimate temperatures was best explained by external temperature and distance from nearest entrance in both caves and culverts. External temperature had a greater influence on microclimate temperatures in culverts than caves. We found that variation in microclimate AWVP was best explained by external temperature, distance from nearest entrance, and proportion from entrance (proportion of the total length of the roost from the nearest entrance) in culvert‐roosting bats. Variation in microclimate AWVP was best explained by external temperature and proportion from entrance in cave‐roosting bats. Our results suggest that bat microclimate temperature and AWVP are influenced by similar factors in both artificial and natural roosts, although the relative contribution of these factors differs between roost types.

The evolution of a bat population with white-nose syndrome (WNS) reveals a shift from an epizootic to an enzootic phase

BackgroundWhite-nose Syndrome (WNS) is a mycosis caused by a cutaneous infection with the fungus Pseudogymnoascus destructans (Pd). It produces hibernation mortality rates of 75–98% in 4 bats: Myotis lucifugus, M. septentrionalis, M. sodalis, and Perimyotis subflavus. These high mortality rates were observed during the first several years after the arrival of P. destructans at a hibernation site. Mortality is caused by a 60% decrease in torpor bout duration, which results in a premature depletion of depot fat prior to spring.ResultsLittle is known about the long-term effects of Pd on torpor and mortality, thus we conducted a 9-year study on M. lucifugus at 5 of the hibernation sites where Pd first appeared in North America during the winter of 2007–08. The M. lucifugus hibernating at one of these sites one year after the arrival of Pd (2008–09) had: a) a mean torpor bout duration of 7.6 d, b) no depot fat reserves by March, and c) an apparent over-winter mortality rate of 88%. The M. lucifugus hibernating at this same site 6–9 years after the arrival of Pd, in contrast, had: a) a mean torpor bout duration of 14.7 d, b) depot fat remaining in March, and c) an apparent mortality rate of 50%. The number of M. lucifugus hibernating at 2 of these sites has consistently increased since 2010 and is now more than 3.0-fold higher than the number remaining after the winter of 2008–09.ConclusionsThese findings indicate that this population of M. lucifugus has evolved mechanisms to hibernate well in the presence of Pd, thus reducing over-winter mortality.

The In-Flight Social Calls of Insectivorous Bats: Species Specific Behaviors and Contexts of Social Call Production

Bats could be a useful study system for studying the evolution of social communication, as they exhibit a high diversity of social group size and complexity. However, the study of bat social calls has been limited, as they are nocturnal, volant animals that produce predominately ultrasonic vocalizations. Passive acoustic monitoring studies occasionally capture bat in-flight social calls. The information from surrounding echolocation calls can provide information on species identity, abundance, and foraging activity. I used passive acoustic monitoring in Greensboro, North Carolina, to identify seven types of in-flight social calls from Eptesicus fuscus, Lasiurus borealis, Lasiurus cinereus, Nycticeius humeralis, Perimyotis subflavus, and Tadarida brasiliensis. Eptesicus fuscus, N. humeralis, and T. brasiliensis differed in total social call production, and the proportional use of call types. Shared called types exhibited species-specific signatures. The presence of species-specific signatures indicates bats could potentially discern signaler identity. Social call production was highest early in the night and positively correlated with bat activity. Eptesicus fuscus and T. brasiliensis most commonly produced complex calls, which appear to mediate social interactions between conspecifics while foraging. Nycticeius humeralis most commonly produced downsweeps, which appear to be broad-functioning contact calls. Upsweeps exhibited a similar context to downsweeps, and were commonly produced by E. fuscus and N. humeralis. My results indicate bats use dedicated social calls to mediate different types of social interactions while in flight.

Interspecific Aggression between a Hoary Bat (Lasiurus cinereus) and a Tricolored Bat (Perimyotis subflavus) in Northern Arkansas

We observed interspecific aggression between a Hoary Bat (Lasiurus cinereus) and a Tricolored Bat (Perimyotis subflavus) along the Buffalo River in northern Arkansas in September 2016. The Hoary Bat presumably captured the Tricolored Bat and repeatedly bit its forearm and facial tissues while on the ground. The Tricolored Bat did not survive the encounter. Interspecific aggression has been observed in Hoary Bats previously and has occasionally been linked to rabies infection. Because of the circumstantial nature of our observation, we were unable to draw specific conclusions as to the nature of this behavior.

Detection Probability of Bats Using Active Versus Passive Monitoring

As technology has evolved, bat researchers have relied more heavily on using acoustic techniques to collect data on bat communities. Acoustic data can be collected actively, where the researcher is present at the sampling point and follows the bat with the detector, or passively, where the researcher is not present and the detector is set out by itself. Active sampling can yield longer, clearer calls, and is only conducted during part of the night (usually from sunset to about 02:00 hours) for short bouts (20 minutes). By contrast, passive sampling can yield lower quality calls, but procedures are easily repeatable and data can be used to measure temporal variation in activity throughout the night and detect individuals and species that are missed during active sampling. Researchers are increasingly attempting to monitor and compare bat communities over time, including sites where both active and passive sampling have occurred. However, these two techniques can yield different detection probabilities and the extent to which data collected using these two techniques can be compared is unclear. Thus, in July 2017 we simultaneously collected acoustic data actively and passively to compare detection probabilities of bats at the Savannah River Site, South Carolina, USA. Using Anabat Express detectors, we detected five species or species groups (Eptesicus fuscus/Lasiurus cinereus, L. borealis/L. seminolus, Perimyotis subflavus, Myotis austroriparius, and Nycticeius humeralis) using each method. Using single season occupancy modeling, we found that method (passive vs. active sampling) had a significant effect on detection probabilities of all species, and that passively sampling throughout the night yielded the highest detection probability for all species. As a result, if differences in detection probability are not taken into account, comparison of historical active datasets with current passive datasets could lead to different insights into habitat use by similar bat communities. Based on our findings, we recommend that researchers use passive sampling throughout the night when studying and monitoring bat communities.

THE STATUS OF PSEUDOGYMNOASCUS DESTRUCTANS IN LOUISIANA

White-nose syndrome (WNS) represents an emerging infectious disease in bats caused by the fungal pathogen Pseudogymnoascus destructans (Pd). The fatal disease has devastated populations of several species of bats in North America, so there is interest in delimiting its current range to aid containment and other management efforts. Early detection of the fungus aids in risk assessment of the disease and managing its presence in areas with hibernating bats. Infection by Pd in bats has been neither surveyed nor reported in Louisiana, despite the fact that WNS has been recorded approximately 150 km across the border of two neighboring states, Arkansas and Mississippi. Between December 2015 and January 2016, we surveyed 190 culverts distributed across the northern portion of Louisiana. In total, we encountered 801 individual bats (355 Perimyotis subflavus, 299 Myotis, 54 Eptesicus fuscus, 47 Tadarida brasiliensis, and 46 Corynorhinus rafinesquii). We used ultraviolet illumination to inspect each individual for presence of WNS symptoms, and no visible symptoms were detected. We also swabbed the skin of 244 bats and 316 habitat walls, and swabs were returned to the laboratory and analyzed using quantitative polymerase chain reaction and Pd-specific primers for presence of the pathogen. No genetic detections occurred in any bat or habitat wall samples. Based on negative detection, we hypothesize that the fungus has not yet been introduced into the state of Louisiana or the environmental conditions of culverts found in Louisiana are not conducive to persistence of the fungus; however, ours is the first survey to assess the status of Pd in the state. Monitoring should continue to confirm that no evidence of the fungal pathogen exists anywhere in the state and to enable rapid response if detection occurs.

Lipolytic Activity and the Utilization of Fatty Acids Associated with Bat Sebum by Pseudogymnoascus destructans.

Pseudogymnoascus destructans is the causative agent of a fungal infection of bats known as white-nose syndrome (WNS). Since its discovery in 2006, it has been responsible for precipitous declines of several species of cave-dwelling North American bats. While numerous advancements in the understanding of the disease processes underlying WNS have been made in recent years, there are still many aspects of WNS, particularly with respect to pathogen virulence, that remain unknown. In this preliminary investigation, we sought to further elucidate the disease cycle by concentrating on the pathogen, with specific focus on its ability to utilize lipids that compose bat wing sebum and are found in wing membranes, as a substrate for energy and growth. In vitro growth experiments were conducted with the three most common fatty acids that comprise bat sebum: oleic, palmitic, and stearic acids. None of the fatty acids were observed to contribute a significant difference in mean growth from controls grown on SDA, although morphological differences were observed in several instances. Additionally, as an accompaniment to the growth experiments, bat wing explants from Perimyotis subflavus and Eptesicus fuscus were fluorescently stained to visualize the difference in distribution of 16- and 18-carbon chain fatty acids in the wing membrane. Which substrates contribute to the growth of P. destructans is important to understanding the progressive impact P. destructans has on bat health through the course of the disease cycle.

White-nose syndrome dramatically altered the summer bat assemblage in a temperate Southern Appalachian forest

White-nose syndrome (WNS), an epizootic disease caused by an invasive fungus, threatens bat populations across North America. WNS-induced changes in summer bat populations could impact functional diversity. We assessed the shift in relative abundance within an assemblage of bats in a temperate southern Appalachian forest in North Carolina and Tennessee from 2009 through 2016. We used mixed linear effects models to identify bat species significantly impacted by WNS and those showing resistance, and to determine effects on reproductive rates for WNS-affected species. Four once-common species — the little brown bat (Myotis lucifugus), Indiana bat (M. sodalis), northern long-eared bat (M. septentrionalis), and tri-colored bat (Perimyotis subflavus) — showed significant and dramatic declines (82–99%), while the big brown bat (Eptesicus fuscus), red bat (Lasiurus borealis), Rafinesque’s big-eared bat (Corynorhinus rafinesquii), and small-footed bat (M. leibii) did not decline significantly after WNS was detected on the landscape. We detected no significant interactions between reproductive condition and WNS period (pre- and post-arrival of the disease). Declines in summer populations mirrored declines detected in nearby winter hibernacula. Because the loss of WNS-affected bat species could negatively impact ecosystem health, it is important to monitor bat, insect, and plant community responses wherever WNS threatens bats. We hypothesize that, in the absence of small-bodied bats, there might be increases in populations of small forest pests, such as defoliating moths, as larger WNS-resistant bats may avoid or miss these small prey.

Winter habitats of bats in Texas.

Few studies have described winter microclimate selection by bats in the southern United States. This is of particular importance as the cold-adapted fungus, Pseudogymnoascus destructans, which causes the fatal bat disease white-nose syndrome (WNS), continues to spread into southern United States. To better understand the suitability of winter bat habitats for the growth of P. destructans in this region, we collected roost temperature and vapor pressure deficit from 97 hibernacula in six ecoregions in Texas during winter 2016-17 and 2017-18. We also measured skin temperature of Rafinesque's big-eared bats (Corynorhinus townsendii), Townsend's big-eared bats (C. townsendii), big-brown bats (Eptesicus fuscus), southeastern myotis (Myotis austroriparius), cave myotis (M. velifer), tri-colored bats (Perimyotis subflavus), and Mexican free-tailed bats (Tadarida brasiliensis) during hibernation to study their use of torpor in these habitats. We found that temperatures within hibernacula were strongly correlated with external air temperatures and were often within the optimal range of temperatures for P. destructans growth. Hibernacula and skin temperatures differed among species, with Rafinesque's big-eared bats, southeastern myotis, and Mexican free-tailed bats occupying warmer microclimates and having higher torpid skin temperatures. For species that were broadly distributed throughout Texas, hibernacula and skin temperatures differed within species by ecoregion; Tri-colored bats and cave myotis in colder, northern regions occupied colder microclimates within hibernacula and exhibited colder skin temperatures, than individuals of the same species in warmer, southern regions. These data illustrate the variability in microclimates used as hibernacula by bats in Texas and suggest similar variation in susceptibility to WNS in the state. Thus, monitoring microclimates at winter roosts may help predict where WNS may develop, and where management efforts would be most effective.

Different management strategies are optimal for combating disease in East Texas cave versus culvert hibernating bat populations

AbstractManagement decisions for species impacted by emerging infectious diseases are challenging when there are uncertainties in the effectiveness of management actions. Wildlife managers must balance trade‐offs between mitigating the effects of the disease and the associated consequences on other aspects of the managed system. An example of this challenge is exemplified in the response to white‐nose syndrome (WNS), a disease of hibernating bats. The fungal pathogen that causes WNS, Pseudogymnoascus destructans, continues to spread throughout North America. Texas, recently confirmed positive for the fungus, has documented 33 bat species in the state, with nearly half of those species naïve to the pathogen. We explicitly incorporated multiple management objectives, uncertainty, and risk in the Texas Parks and Wildlife Department decision to manage East Texas populations of the tri‐colored bat (Perimyotis subflavus), a species highly susceptible to WNS. Alternatives included individual actions that act against P. destructans or benefit bats, a no active management option, and combinations of actions. Although our main objective was to identify WNS mitigation measures for tri‐colored bats in culverts, we also considered the transferability of the decision for natural caves. In this scenario, the optimal decision differed for culverts and caves, with a “portfolio” combination of actions ranking as the best alternative for culverts and a single vaccine alternative for caves. Because the top management alternatives differed markedly between these two systems, finding treatments that have broad application is likely infeasible, given that each management decision is characterized by different mixtures of competing objectives.

Spring Migration Behavior of a Perimyotis subflavus (Tri-Colored Bat) from Tennessee

On the nights of 27, 28, and 29 April 2018, we used aerial radio-telemetry to track a female Perimyotis subflavus (Tri-colored Bat) as she migrated a straight-line distance of 243 km from a cave in southern Tennessee to a roost in Peachtree City, GA. To our knowledge, this represents the longest and most detailed spring migration track recorded for this species and places the Tri-colored Bat in the category of regional migrant.

Structural and environmental predictors of presence and abundance of tri-colored bats in Texas culverts

AbstractThe tri-colored bat (Perimyotis subflavus) is being reviewed for listing under the Endangered Species Act by the United States Fish and Wildlife Service. It is also listed as a species of greatest conservation need by the Texas Parks and Wildlife Department due to its susceptibility to white-nose syndrome (WNS) in other states. Several colonies of hibernating tri-colored bats have been documented roosting in culverts. Culverts are widespread in Texas as part of roadway infrastructure; thus, our objective was to understand and quantify which structural and environmental factors best explain culvert use and abundance of hibernating tri-colored bats in Texas. We selected and surveyed 207 culverts for presence of tri-colored bats using the Generalized Random Tessellation Stratified (GRTS) design and opportunistic sampling across 10 of 12 Texas level III ecoregions during the winters of 2016–2017 and 2017–2018. We recorded environmental and structural features of culverts at each site. We used a zero-inflated Poisson regression to identify which culvert features best explained presence and abundance of hibernating tri-colored bats. We found that number of culvert sections predicted presence of tri-colored bats. We also found that abundance of tri-colored bats was influenced by length of culvert, elevation, number of sections, portal height, portal obstruction, aspect, external VPD, external temperature, and NDVI. With the current threats to tri-colored bat populations, there is a need to consider management of culvert roosts. In addition, it is imperative to further investigate the potential susceptibility to WNS of culvert-roosting bats at more southern latitudes for local and regional planning efforts.

Effects of fire and its severity on occupancy of bats in mixed pine-oak forests

Prescribed burning has become more common for the management of eastern forests in North America, so understanding if and how foraging bats respond to structural changes generated by fire is of increasing importance. Our objective was to investigate the effects of post-fire landscape conditions on the occurrence of foraging bats in mixed forests of the Cumberland Plateau physiographic region. We deployed Anabat II bat detectors in 164 paired burned and unburned forest sites for ≥2 nights from mid-May through August 2014 and 2015 to monitor bat foraging and commuting habitat use. We conducted vegetation surveys to quantify site-specific structural characteristics, which indicated that measures of structure were significantly lower in burned sites than unburned sites. We used Program Presence to test a priori hypotheses of species-specific probability of detection and site occupancy related to weather, burn history (i.e., site burned within the past 10 years or unburned), and site and landscape characteristics. Bats were detected at 94% of burned sites and 83% of unburned sites. Probability of detection was affected by weather conditions, vegetative structure, and burn history for most species. Occupancy for all species/species groups examined was positively associated with burning and generally associated with lower vegetative structure. Although burn severity did not affect most species groups, occupancy of Myotis species and tri-colored bats (Perimyotis subflavus) was lower in sites that received moderate severity burns than in sites that received low severity burns. Therefore, while prescribed fire may provide vegetative structure conducive to efficient foraging for all bats of the Cumberland Plateau, our results demonstrate that retaining some unburned forests while creating mosaics of lower and higher severity burns across the landscape will result in favorable foraging conditions for all resident bat species.

VARIATION IN THE NUMBER OF HIBERNATING CAVE MYOTIS (MYOTIS VELIFER) IN WESTERN OKLAHOMA AND NORTHWEST TEXAS CAVES PRIOR TO THE ARRIVAL OF WHITE-NOSE SYNDROME

We report on variation in abundance of hibernating cave myotis (Myotis velifer) prior to the arrival of White-nose Syndrome. The report is based on cave surveys and literature reports in gypsum caves of western Oklahoma and the Texas panhandle. From 1988 to 2017, 34,625–195,234 M. velifer were estimated to occur in the hibernacula surveyed. This report provides important preexposure baseline data on population sizes in the region and will help researchers quantify the impact as the disease spreads into new environs. The population estimates will also serve as a data set for other research. Other species of bats encountered in the surveys were Townsend's big-eared bat (Corynorhinus townsendii), the tricolored bat (Perimyotis subflavus), and the big brown bat (Eptesicus fuscus). The changes in population sizes at the various hibernacula might be owing to a variety of factors, including annual variations in hibernacula microclimates, structural changes in hibernacula, changes in distribution patterns, ability of surveyors to locate and count bats, alterations of the surrounding habitats near hibernacula, or other unknown factors.

A Comparison of Bat Activity in a Managed Central Hardwood Forest

Bats exploit forest resources based on species-specific adaptations, resulting in differences in activity across forested landscapes. Forest management practices alter forests, impacting species differently and presumably affecting bat activity. Application of forest management that promotes species-specific bat conservation requires further understanding of bat response to silvicultural practices. We surveyed timber harvest treatments on two Indiana State Forests to compare bat activity across forest management treatments, in forests adjacent to harvests, and at locations across the harvest-forest gradient from May to July in 2013 and 2014. We used Wildlife Acoustics Song Meter SM2BAT+ detectors and Kaleidoscope Pro analysis software to survey bats in relation to four treatment types: clear cut, patch cut, shelterwood preparatory cut, and intact forest. Detectors were deployed at two points within each treatment and three points on the forested periphery of treatments and recorded for three consecutive nights. We examined bat activity using N-mixture models that estimate abundance and probability of detection for an open population and used Akaike's Information Criterion to select the best models. Based on identification of acoustic calls, eastern red bats and hoary bats were more active in harvest treatments than control treatments. Big brown, eastern red, and tri-colored bats were most active at harvest edges. Northern long-eared and Indiana/little brown bats were most active at harvest edges and in adjacent forest and hoary bats were most active at harvest centers. Differences in bat activity across these managed forests suggest bat assemblages benefit from management that employs an array of silvicultural methods, provides edge habitat, and maintains adjacent forest stands. Our results can be used to predict effects of forest management practices on species-specific bat activity to maximize bat usage of forests.

Bats in Southwest Wisconsin During the Era of White-Nose Syndrome

Since 2004, my students and I have caught and examined 1441 individual bats representing 7 species from mist-net surveys in Grant County, WI. Across all years and sites, Myotis lucifugus (Little Brown Bat) was the most frequently captured bat (59.6% of all captures). We captured over 78% (n = 1106) of bats within the first 120 min after sunset. Based on the capture of lactating females, the following species raise young in southwest Wisconsin: Eptesicus fuscus (Big Brown Bat), Perimyotis subflavus (Tri-colored Bat), Little Brown Bat, M. septentrionalis (Northern Long-eared Bat), Lasiurus borealis (Eastern Red Bat), and L. cinereus (Hoary Bat). Secondary sexual dimorphism was most evident in Big Brown Bats and Eastern Red Bats. Trends at 1 primary research site for the 3 most commonly captured species showed that, from 2007 to 2017, there was no significant change in number of bats captured per mist-net-meter-hour for Big Brown Bats and Eastern Red Bats. In contrast, and coincident with the occurrence of white-nose syndrome in Wisconsin, there was a signicant decline in the number of Little Brown Bats captured per mist-net-meter-hour over that same time period. Monitoring of bat populations in southwest Wisconsin should continue.