Summer Bat Research Articles

Heart rate monitoring reveals differential seasonal energetic trade-offs in male noctule bats.

Understanding how animals meet their daily energy requirements is critical in our rapidly changing world. Small organisms with high metabolic rates can conserve stored energy when food availability is low or increase energy intake when energetic requirements are high, but how they balance this in the wild remains largely unknown. Using miniaturized heart rate transmitters, we continuously quantified energy expenditure, torpor use and foraging behaviour of free-ranging male bats (Nyctalus noctula) in spring and summer. In spring, bats used torpor extensively, characterized by lowered heart rates and consequently low energy expenditures. In contrast, in summer, bats consistently avoided torpor, even though they could have used this low-energy mode. As a consequence, daytime heart rates in summer were three times as high compared with the heart rates in spring. Daily energy use increased by 42% during summer, despite lower thermogenesis costs at higher ambient temperatures. Likely, as a consequence, bats nearly doubled their foraging duration. Overall, our results indicate that summer torpor avoidance, beneficial for sperm production and self-maintenance, comes with a high energetic cost. The ability to identify and monitor such vulnerable energetic life-history stages is particularly important to predict how species will deal with increasing temperatures and changes in their resource landscapes.

Acoustic monitoring yields informative bat population density estimates.

Bat population estimates are typically made during winter, although this is only feasible for bats that aggregate in hibernacula. While it is essential to measure summer bat population sizes for management, we lack a reliable method. Acoustic surveys should be less expensive and more efficient than capture surveys, and acoustic activity data are already used as indices of population size. Although we currently cannot differentiate individual bats by their calls, we can enter call counts, information on signal and detection angles, and weather data into generalized random encounter models to estimate bat density. We assessed the utility of generalized random encounter models for estimating Indiana bat (Myotis sodalis) population density with acoustic data collected at 51 total sites in six conservation areas in northeast Missouri, 2019-2021. We tested the effects of year, volancy period, conservation area, and their interactions on estimated density. Volancy period was the best predictor, with average predicted density increasing 60% from pre-volancy (46 bats/km2) to post-volancy (74 bats/km2); however, the magnitude of the effect differed by conservation area. We showed that passive acoustic surveys yield informative density estimates that are responsive to temporal changes in bat population size, which suggests this method may be useful for long-term monitoring. However, we need more information to choose the most appropriate values for the density estimation formula. Future work to refine this approach should include assessments of bat behavior and detection parameters and testing the method's efficacy in areas where population sizes are known.

Data on the summer bat fauna of Belarus in 2017–2020

This report presents the results of the bat fauna survey carried out in Belarus during the warm seasons between 2017 and 2020. The presented data were collected in 31 localities in all six administrative regions (voblasćs) of Belarus during field studies (mist-netting, searching for roosts and colonies, and acoustic surveys) and in the course of the work of the Minsk bat contact centre. Field data refer to 26 localities; acoustic observations to 14 localities; and netting was carried out in 19 localities (151 ind.). The data on bats collected via the contact centre came from 6 localities (35 ind.). In the course of our survey, we recorded 13 out of the 19 species of the Belarusian bat fauna. They are Barbastella barbastellus, Eptesicus nilssonii, E. serotinus, Myotis dasycneme, M. daubentonii, Nyctalus lasiopterus, N. leisleri, N. noctula, Pipistrellus kuhlii, P. nathusii, P. pygmaeus, Plecotus auritus, and V. murinus. The occurrence of all recorded species was confirmed by direct identification. Data on breeding have been added for all recorded species except for N. lasiopterus and B. barbastellus. Data on breeding have been added for all recorded species, except for N. lasiopterus and B. barbastellus. Maternity colonies were recorded for E. serotinus, M. dasycneme (the second record of a maternity colony of the species for the entire period of research in Belarus) and M. daubentonii. The largest number of individuals recorded by the contact centre represent V. murinus; other species in descending order are E. serotinus, N. noctula, P. auritus, P. nathusii, B. barbastellus, M. daubentonii, P. kuhlii, and E. nilssonii. Among the netted individuals, P. nathusii prevailed; other species in descending order were M. daubentonii, P. pygmaeus, E. nilssonii, P. auritus, N. noctula, E. serotinus, M. dasycneme, N. leisleri, and N. lasiopterus. Three species (V. murinus, B. barbastellus, and P. kuhlii) were presented only among bats reported via the contact centre. During the survey, the species P. pipistrellus, Pl. austriacus, M. brandtii, M. nattereri, M. myotis, and M. mystacinus included in the list of mammal species of Belarus were not recorded. The reasons of the lack of records of these six species are discussed. The collected data contribute to the general knowledge on the distribution, breeding, and status of bat species in Belarus and Eastern Europe.

Evaluating the risk of SARS‐CoV‐2 transmission to bats in the context of wildlife research, rehabilitation, and control

Preventing wildlife disease outbreaks is a priority for natural resource agencies, and management decisions can be urgent, especially in epidemic circumstances. With the emergence of SARS‐CoV‐2, wildlife agencies were concerned whether the activities they authorize might increase the risk of viral transmission from humans to North American bats, but had a limited amount of time in which to make decisions. We describe how decision analysis provides a powerful framework to analyze and reanalyze complex natural resource management problems as knowledge evolves. Coupled with expert judgment and avenues for the rapid release of information, risk assessment can provide timely scientific information for evolving decisions. In April 2020, the first rapid risk assessment was conducted to evaluate the risk of transmission of SARS‐CoV‐2 from humans to North American bats. Based on the best available information and relying heavily on expert judgment, the risk assessment found a small possibility of transmission during summer work activities. Following that assessment, additional knowledge and data emerged, such as bat viral challenge studies, that further elucidated the risks of human‐to‐bat transmission and culminated in a second risk assessment in the fall of 2020. We updated the first SARS‐CoV‐2 risk assessment with new management alternatives and new estimates of little brown bat (Myotis lucifugus) susceptibility, using findings from the fall 2020 assessment and other empirical studies. We found that new knowledge led to an 88% decrease in the median number of bats estimated to be infected per 1,000 encountered when compared to earlier results. The use of facemasks during, or a negative COVID‐19 test or vaccination prior to, bat encounters further reduced those risks. Using a combination of decision analysis, expert judgment, rapid risk assessment, and efficient modes of information distribution, we provided timely science‐based support to decision makers for summer bat work in North America.

White‐nose Syndrome and Environmental Correlates to Landscape‐Scale Bat Presence

ABSTRACTOver the past 13 years, White‐nose Syndrome (WNS) has caused North American bat population declines and shifted community structure towards species less or unaffected by the disease. Mist‐netting, acoustic surveys, and cave count data have been used to document changes in bat presence and activity through site‐specific, pre‐ and post‐WNS studies. Management and survey guidance often must be applied at a combined landscape and site‐specific scale. Our objective was to explore the relationships among WNS impact, influence of available hibernacula, and environmental factors for the nightly presence of 3 WNS‐affected bats: the Indiana bat (Myotis sodalis), northern long‐eared bat (M. septentrionalis), and big brown bat (Eptesicus fuscus). We used recordings from 10 acoustic monitoring study areas, each with 3 survey locations across the states of Virginia, West Virginia, Ohio and Kentucky to assess changes in nightly bat presence during the summer of 2017. There were significant positive and negative correlates of broad land‐cover categories for presence of all 3 bat species. Our findings also corroborated trends in abundance and distribution patterns found in prior, smaller‐scale studies, supporting the relevance of land cover categories in a large‐scale acoustic monitoring framework. We observed a negative association between WNS impact‐years and nightly northern long‐eared bat presence, but low occurrence and patchy distribution reduced our ability to infer strong relationships. Big brown bat presence showed a significant positive relationship with WNS occurrence on the landscape, providing evidence that big brown bats are maintaining populations after years of exposure. Indiana bats were the least‐documented species, limiting the strength of our conclusions, but we did observe significant temporal patterns in nightly presence, with higher probabilities of presence earlier in the summer. Our results show the potential efficacy of using a WNS impact metric to predict summer bat presence, inform current U.S. Fish and Wildlife Service acoustic monitoring guidelines, and highlight which environmental variables are relevant for large‐scale acoustic monitoring. © 2021 The Wildlife Society. This article has been contributed to by US Government employees and their work is in the public domain in the USA.

Behavioral patterns of bats at a wind turbine confirm seasonality of fatality risk.

Bat fatalities at wind energy facilities in North America are predominantly comprised of migratory, tree‐dependent species, but it is unclear why these bats are at higher risk. Factors influencing bat susceptibility to wind turbines might be revealed by temporal patterns in their behaviors around these dynamic landscape structures. In northern temperate zones, fatalities occur mostly from July through October, but whether this reflects seasonally variable behaviors, passage of migrants, or some combination of factors remains unknown. In this study, we examined video imagery spanning one year in the state of Colorado in the United States, to characterize patterns of seasonal and nightly variability in bat behavior at a wind turbine. We detected bats on 177 of 306 nights representing approximately 3,800 hr of video and > 2,000 discrete bat events. We observed bats approaching the turbine throughout the night across all months during which bats were observed. Two distinct seasonal peaks of bat activity occurred in July and September, representing 30% and 42% increases in discrete bat events from the preceding months June and August, respectively. Bats exhibited behaviors around the turbine that increased in both diversity and duration in July and September. The peaks in bat events were reflected in chasing and turbine approach behaviors. Many of the bat events involved multiple approaches to the turbine, including when bats were displaced through the air by moving blades. The seasonal and nightly patterns we observed were consistent with the possibility that wind turbines invoke investigative behaviors in bats in late summer and autumn coincident with migration and that bats may return and fly close to wind turbines even after experiencing potentially disruptive stimuli like moving blades. Our results point to the need for a deeper understanding of the seasonality, drivers, and characteristics of bat movement across spatial scales.

Summer Bat Habitat Use and Forest Characteristics in Managed Northeastern Forests

AbstractThere has been limited research investigating summer habitat use of bats in managed forests in the northeastern United States. Consequently, there is limited knowledge to inform forest managers seeking to maintain or enhance bat habitat, particularly for several federally threatened, endangered, or candidate species. In summer 2017–2018, we conducted repeated acoustic surveys to determine what forest characteristics are associated with bat habitat use in managed forests in the Adirondack region of upstate New York. We modeled detection corrected probability of occupancy for bats in three phonic groups: high, mid, and low frequency. Across all phonic groups, probability of occupancy increased with decreasing canopy cover. High-, mid-, and low-frequency bats were more likely to use recently harvested sites (<10 years since harvest). High-frequency bats also used mature stands. Midfrequency bats demonstrated a preference for further distances from forest roads, whereas low-frequency bats preferred areas with a higher percentage of clutter. Our results suggest that tending and regenerating even-aged forest management practices can provide habitat for foraging bats in the Adirondacks.

Changes in a summer bat community in southeastern Pennsylvania

Abstract Bat population changes are poorly understood, making it difficult to establish management priorities. In 2017, a summer mist-netting survey previously conducted in 2004 at Fort Indiantown Gap was replicated to evaluate temporal changes in the local bat community. The authors hypothesized that captures of species most affected by white-nose syndrome (WNS) would decline between survey periods, and that community structure would shift. The results showed a 100% decline in captures of northern long-eared Myotis (Myotis septentrionalis) and little brown Myotis (M. lucifugus), no change in captures of eastern red bats (Lasiurus borealis), a 276% increase in captures of big brown bats (Eptesicus fuscus), and a considerable shift in community structure. These results are consistent with expected effects of WNS on Myotis populations. Increases in big brown bat populations may result from ecological release after the decline of Myotis species, or from local or large-scale habitat change over time.

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.

Orientation and flight behaviour identify the Soprano pipistrelle as a migratory bat species at the Baltic Sea coast

AbstractMigration routes of bats remain largely unknown, as previous orientation studies have been challenging even with newly developed techniques in tracking, genetic and stable isotope studies. However, a lack of knowledge about migrations poses problems for species conservation, especially in newly described species for which ecological information is not yet available. Here, we aimed to test flight orientation behaviour in the Soprano pipistrelle, Pipistrellus pygmaeus. This species has been described only 22 years ago but is now known to have a wide geographic distribution in Europe, yet virtually no information exists about seasonal movements of P. pygmaeus. In large parts of the continent, seasonal occurrence of P. pygmaeus matches with that of long‐distance migratory Nathusius' bats (Pipistrellus nathusii). To shed light on the migratory behaviour of both species, we investigated their orientation decisions at the Latvian Baltic Sea coast which is well‐known for summer bat migration along a north‐south axis. We developed an arena‐based assay designed to measure orientation of takeoffs. The arena was installed in the natural flight path of P. nathusii and P. pygmaeus, and after takeoff, bats chose the direction freely. We detected bearing fidelity between takeoff and departure flights, suggesting that bats used cues within the arena, putatively geomagnetic information, which allowed them to set a course prior to takeoff. Furthermore, our results show that P. pygmaeus orientates in a southerly, seasonally appropriate direction, similar to P. nathusii during ongoing migration. Therefore, our findings are consistent with true migratory behaviour of P. pygmaeus in the northern part of its range. Predicting flight directions of bats based on takeoff direction offers a simple test for orientation studies, and could further be used to test senses of bats under varying treatments, thereby facilitating a comparison of navigational skills across taxa, e.g., bats and birds.

Summer activity patterns of four resident south Texas bat species

Although the activity patterns of bats are recognized to vary widely, both, temporally and spatially, the underlying drivers for those patterns remain poorly understood. Presently, studies focusing on foraging bat ecology have only generalized activity and influence of the environment (across sampling periods, sampling nights, or seasons). The influence of environmental features on foraging bat activity on a finer temporal scale (e.g., throughout a single sampling night) is markedly less studied. The recent emergence of Pseudogymnoascus destructans, a cold-adapted fungus and the causative agent of white-nose syndrome (WNS), has led to the precipitous declines in North American bat populations since its arrival in 2006. P. destructans has been recently documented in 10 Texas counties and, although WNS primarily affects hibernation cycles, it is recognized to have significant detrimental impacts on summer bat activity. It is imperative we understand and provide a baseline of summer bat activity patterns prior to the arrival of WNS to better manage and protect these, relatively understudied, populations of bat species in south Texas. We used a mixed model approach and acoustic monitoring to quantify how shrub density, canopy height, distance to water, roads, and bare ground coverage influenced nightly foraging activities of four summer resident bat species in south Texas: Eastern Red Bat (Lasirius borealis), Cave Myotis (Myotis velifer), Evening Bat (Nycticeius humeralis), and Brazilian Free-tailed Bat (Tadarida brasiliensis). Total bat activity peaked at 2:00-a for all species included in our study. A secondary, smaller peak was notable between 5:00-a and 6:00-a and activity decreased sharply immediately following 6:00-a. However, the trend for total bat activity differed substantially from trends exhibited by the individual species. Eastern red-bats and Evening bats exhibited bimodal nightly activity patterns and showed variable associations with water proximity whereas Cave bats and Brazilian free-tailed bats exhibited unimodal activity patterns and strong associations with canopy height and roads. Our results support the concept that insectivorous bats partition resources, temporally and spatially, in the presence of other sympatric species.

Notes on Capture and Roost Characteristics of Three Female Evening Bats (Nycticeius humeralis) in Southern Wisconsin: An Expanding Species?

Abstract The evening bat (Nycticeius humeralis) is considered a common species in southeastern United States, with historically few records in the Upper Midwest region of the United States. However, recent work in Michigan and Minnesota has shown that evening bats are becoming increasingly common in the region. After capture of a juvenile male evening bat in late summer 2015 in southern Rock County, Wisconsin, we radio-tracked three adult female evening bats in summer 2016 at the same Rock County location. These three bats were tracked to three roost trees with counts during evening emergence ranging from 20 to 103 bats. This work represents the first confirmed capture and roost site investigation for evening bats in Wisconsin and supports the idea this species is expanding its range.

How to keep cool in a hot desert: Torpor in two species of free-ranging bats in summer

ABSTRACTSmall insectivorous tree-roosting bats are among the most taxonomically diverse group of mammals in Australia's desert, yet little is known about their thermal physiology, torpor patterns and roosting ecology, especially during summer. We used temperature-telemetry to quantify and compare thermal biology and roost selection by broad-nosed bats Scotorepens greyii (6.3 g; n = 11) and Scotorepens balstoni (9.9 g; n = 5) in Sturt National Park (NSW Australia) over 3 summers (2010–13). Both vespertilionids used torpor often and the total time bats spent torpid was ∼7 h per day. Bats rewarmed using entirely passive rewarming on 44.8% (S. greyii) and 29.4% (S. balstoni) of all torpor arousals. Both bat species roosted in hollow, cracked dead trees relatively close to the ground (∼3 m) in dense tree stands. Our study shows that torpor and passive rewarming are 2 common and likely crucial survival traits of S. greyii and S. balstoni.

Contribution to Ecology of Brandts Bat, Myotis Brandtii (Chiroptera, Vespertilionidae), in the North-Eastern Ukraine: Comparison of Local Summer and Winter Bat Assemblages

AbstractThe Brandt’s Bat (Myotis brandtii Eversmann, 1845) is one of the rarest bat species in Ukraine. There are only a few known locations of this species in summer and less known hibernacula in the whole country. Moreover, for territory of the north-eastern Ukraine are known only two underground bat hibernation sites with aggregation more than several tens of individuals. We undertook population surveys of winter aggregations in newly discovered and dug up abandoned sandstone mines in the Chuguev district of the Kharkiv Region (49°54′ N, 36°43′ E) from 2007 through 2015. We also surveyed summer bat assemblages in the forests surrounding these mines in 2012. The mines’ microclimate conditions were as follows: temperature +6 °C - +10 °C and humidity 60-80 %. M. brandtii, M. daubentonii (Kuhl, 1817) and Plecotus auritus (Linnaeus, 1758) hibernate in the mines; the first species is most abundant by number of individuals. In midsummer 9 bat species were recorded including the three previously mentioned. M. daubentonii and P. auritus breed in surrounding forest, but M. brandtii does not. One recaptured individual of M. brandtii was minimum 6 years old, providing us the first recorded information on longevity of this species for Ukraine. The total number of bats hibernating in these mines is estimated to be up to 100 individuals; a hibernaculum with several tens of M. brandtii could be classified as more numerous for this species in Ukraine. For this reason, the system of mines in the Kharkiv region needs species protection status and an action plan for monitoring and management.

Structure of summer bat assemblages in forests in European Russia

We used mist-netting to study summer bat assemblages in 3 state nature biosphere reserves in the European part of Russia from 26 June to 29 July 2013: Oksky, Ryazan region (54°44'N, 40°54'E); Voronezhsky, Voronezh region (51°55'N, 39°38'E); and "Bryansky Les", Bryansk region (52°27'N, 33°53'E). The main research efforts were in locations where Nyctalus lasiopterus had been captured in the past. In total, 1229 specimens of 12 bat species (Myotis daubentonii, M. dasycneme, M. brandtii, M. mystacinus, Nyctalus noctula, N. lasiopterus, N. leisleri, Eptesicus serotinus, Pipistrellus nathusii, P. pygmaeus, Vespertilio murinus, and Plecotus auritus) were caught. N. lasiopterus (a female subadult) was confirmed only in the Voronezhsky Reserve. The bat assemblages could be classified as forest-dwelling and dominated by long-distance migratory species (genera Nyctalus, Pipistrellus, and Vespertilio). Females also dominated and breeding was recorded for most of the species. The highest bat abundance (b/h index: 4.54) was in the Voronezhsky Reserve (the most southeasterly location) and the lowest (b/h index: 1.75) was in "Bryansky Les" (the most southwesterly location). The Shannon-Wiener index was higher in the Voronezhsky and Oksky Reserves but the evenness index was similar for all reserves. Bat assemblage structure in strictly protected forest areas (such as the Voronezhsky Reserve) has been stable for decades.

Empty in summer, crowded during migration? Structure of assemblage, distribution pattern and habitat use by bats (Chiroptera: Vespertilionidae) in a narrow, marine peninsula

According to scarce available data, the use of coastal habitats by bats appears to be the most intensive during spring and autumn migrations, when coasts become migratory corridors. Migrating bats might seasonally enrich the fauna of sea islands and peninsulas, which often are poor in bats outside the migratory season. Hel Peninsula is part of the Polish Baltic Coast that extends the most into the sea; thus, it gives unique opportunity to assess that phenomenon quantitatively. To test for seasonal variation in structure of bat assemblage and bat activity, we recorded echolocation calls on walking transects. Seven species were recorded in total, with predominance of sedentary Eptesicus serotinus in June–July and migratory Pipistrellus nathusii in August–September. Occurrence of bats was the highest in deciduous and coniferous forests and the lowest in coasts and ports. Interaction of day of year and distance to mainland was highly significant, indicating that occurrence of bats was increasing from spring to autumn but this increase depended on location. Far from mainland, the mean occurrence of bats was rather stable over time. On transects located close to the mainland, bat occurrence was low at the beginning of the season but after mid-August increased rapidly. We confirmed that some topographically isolated parts of the sea coasts can host only very impoverished summer bat fauna. Bat activity in such sites increase in autumn; however, Hel Peninsula presumably does not act as a migratory corridor, but only as a target of local dispersal from mainland.

Structure and Reproductive Patterns in the Summertime Forest-Bat Community of Southeastern Texas

Abstract Forests of eastern Texas represent the westernmost extent of the southern pine forests and part of the pine belt of the forested Gulf coastal plain. Bat community assemblages in similar forests throughout southeastern United States have been documented in various studies, but only scant data are available for Texas. The purpose of this study was to characterize the assemblage and investigate reproductive patterns of the summer bat community in the austroriparian forest of eastern Texas. Using mist nets, we captured bats during summers 2009–2011 and recorded species, gender, age and reproductive condition. We captured 382 bats of eight species: Seminole Lasiurus seminolus (n = 163), evening Nycticeius humeralis (n = 86), big brown Eptesicus fuscus (n = 57), eastern red Lasiurus borealis (n = 31), southeastern myotis Myotis austroriparius (n = 21), tri-colored Perimyotis subflavus (n = 19), Mexican free-tailed Tadarida brasiliensis (n = 4), and hoary Lasiurus cinereus (n = 1) bats. Analysis of reproductive data suggests that three of these species (big brown, evening, and Seminole bats) may be following a reproductive strategy—extended seasonal monoestry (births of single litters spanning a particular season)—different than their previously reported pattern of synchronous monoestry.

Evaluation of Mobile Acoustic Techniques for Bat Population Monitoring

Understanding population trends of any species is essential for conservation and management. However, due to difficulty in sampling some species, population status of many bat species is poorly understood. In an effort to resolve this issue, especially in light of emerging threats (e.g., white-nose syndrome and wind energy), a national mobile acoustic monitoring protocol, modeled after European programs, was developed to survey summer bat populations in the United States. While the program calls for conducting transects along roadways, some have suggested that waterways may allow for the gathering of more information. Therefore, we quantified species richness and abundance along car and boat transects to identify the most efficient mobile method. Furthermore, to compare the capabilities of mobile acoustic transects to a more traditional and better understood survey method, we compared species density along transects to stationary acoustic detectors. Using sample-based rarefaction, there was no difference ...

Capture and Reproductive Trends in Summer Bat Communities in West Virginia: Assessing the Impact of White-Nose Syndrome

Abstract Although it has been widely documented that populations of cave-roosting bats rapidly decline following the arrival of white-nose syndrome (WNS), longer term reproductive effects are less well-known and essentially unexplored at the community scale. In West Virginia, WNS was first detected in the eastern portion of the state in 2009 and winter mortality was documented in 2009 and 2010. However, quantitative impacts on summer bat communities remained unknown. We compared “historical” (pre-WNS) capture records and reproductive rates from 11,734 bats captured during summer (15 May to 15 August) of 1997–2008 and 1,304 captures during 2010. We predicted that capture rates (number of individuals captured/net-night) would decrease in 2010. We also expected the energetic strain of WNS would cause delayed or reduced reproduction, as denoted by a greater proportion of pregnant or lactating females later in the summer and a lower relative proportion of juvenile captures in the mid–late summer. We found a dramatic decline in capture rates of little brown Myotis lucifugus, northern long-eared M. septentrionalis, small-footed M. leibii, Indiana M. sodalis, tri-colored Perimyotis subflavus, and hoary Lasiurus cinereus bats after detection of WNS in 2009. For these six species, 2010 capture rates were 10–37% of pre-WNS rates. Conversely, capture rates of big brown bats Eptesicus fuscus increased by 17% in 2010, whereas capture rates of eastern red bats Lasiurus borealis did not change. Together, big brown and eastern red bats were 58% of all 2010 captures but only 11% of pre-WNS captures. Reproductive data from 12,314 bats showed shifts in pregnancy and lactation dates, and an overall narrowing in the windows of time of each reproductive event, for northern-long-eared and little brown bats. Additionally, the proportion of juvenile captures declined in 2010 for these species. In contrast, lactation and pregnancy rates of big brown and eastern red bats, and the proportion of juveniles, were similar to historical patterns. Our results further elucidate the significance of short-term effects and provide a basis to examine long-term consequences of WNS.

Patterns of Acoustical Activity of Bats Prior to and Following White-Nose Syndrome Occurrence

Abstract White-nose Syndrome (WNS), a wildlife health concern that has decimated cave-hibernating bat populations in eastern North America since 2006, began affecting source-caves for summer bat populations at Fort Drum, a U.S. Army installation in New York in the winter of 2007–2008. As regional die-offs of bats became evident, and Fort Drum's known populations began showing declines, we examined whether WNS-induced change in abundance patterns and seasonal timing of bat activity could be quantified using acoustical surveys, 2003–2010, at structurally uncluttered riparian–water habitats (i.e., streams, ponds, and wet meadows). As predicted, we observed significant declines in overall summer activity between pre-WNS and post-WNS years for little brown bats Myotis lucifugus, northern bats M. septentrionalis, and Indiana bats M. sodalis. We did not observe any significant change in activity patterns between pre-WNS and post-WNS years for big brown bats Eptesicus fuscus, eastern red bats Lasiurus borealis, or the small number of tri-colored bats Perimyotis subflavus. Activity of silver-haired bats Lasionycteris noctivagans increased from pre-WNS to post-WNS years. Activity levels of hoary bats Lasiurus cinereus significantly declined between pre- and post-WNS years. As a nonhibernating, migratory species, hoary bat declines might be correlated with wind-energy development impacts occurring in the same time frame rather than WNS. Intraseason activity patterns also were affected by WNS, though the results were highly variable among species. Little brown bats showed an overall increase in activity from early to late summer pre-WNS, presumably due to detections of newly volant young added to the local population. However, the opposite occurred post-WNS, indicating that reproduction among surviving little brown bats may be declining. Our data suggest that acoustical monitoring during the summer season can provide insights into species' relative abundance on the landscape as affected by the occurrence of WNS.