Big Brown Bats Eptesicus Fuscus Research Articles

Bats to belugas: Functional anatomy of air versus water biosonar

Acoustic task similarities of odontocetes (toothed whales) and microchiropterans (insectivorous bats) suggest they have common biosonar mechanisms. However, media differences; e.g., sound speeds in air versus water, may have driven variations in auditory system adaptations. We examined the peripheral auditory system of an FM bat (big brown bat Eptesicus fuscus) and two toothed whale species (harbor porpoise Phocoena phocoena; bottlenose dolphin Tursiops truncatu) using ultra high resolution (11 μm) isotropic voxel microCT. Significant differences were found among species for oval window location, cochlear length, basilar membrane gradients, cochlear spiral morphometry, cochlear curvature, and basilar membrane stiffness. High and low frequency hearing range cut-offs correlate with basilar membrane thickness/width ratios and cochlear radii of curvature. These features predict species specific high and low frequency hearing limits. Harbor porpoises, the highest frequency echolocator in the study, have large basal basilar membrane ratios and a “foveal” region with a constant membrane ratio similar to those reported for some bat species, consistent with a “stretched” frequency region. Furthermore, both the bats and harbor porpoises examined displayed unusual stapedial input locations and tightly coiled cochleae, specializations that may enhance ultrasonic frequency signal resolution and diminish low frequency cochlear propagation.

Optimizing Surveys for Imperiled Bat Species Post White-Nose Syndrome

Many bat populations have plummeted in North America since the introduction of white-nose syndrome (WNS) in 2006, presenting challenges in researching population health and habitat use of affected species. Traditional survey techniques such as mist-netting and radio-telemetry have become increasingly time-consuming post-WNS due to the rarity of WNS-susceptible species in affected areas. To address the difficulty of studying imperiled bat species, we explored the use of an acoustic lure alongside mist-netting and acoustic monitoring to potentially enhance species detection in southeastern Missouri, United States. Acoustic lures elicit varying intra- and interspecific behavioral responses; thus, we explored the effects on multiple bat species' encounter rates while using tricolored bat Perimyotis subflavus distress vocalizations. The acoustic lure increased the number of acoustic detections for the federally endangered Indiana bat Myotis sodalis and non-imperiled big brown bat Eptesicus fuscus, and increased captures of the silver-haired bat Lasionycteris noctivagans, a species of conservation concern in Missouri. Additionally, only two individuals of P. subflavus were captured in mist-nets, and both were captured with the acoustic lure. These results suggested that acoustic lures are a valuable tool for identifying the presence of imperiled species when used in combination with mist-netting and acoustic detectors. Researchers studying bat communities that have experienced significant population declines because of WNS or other factors should incorporate multiple survey techniques, including acoustic lures, to increase capture rates and better document species distributions. Doing so should provide more accurate information on the distribution of imperiled bat species, which is relevant to conservation and management.

Whole Genome Sequencing and Phylogenetic Analysis of Rabies Viruses from Bats in Connecticut, USA, 2018-2019.

We performed whole genome sequencing and genetic characterization of rabies viruses (RABV) detected in bats submitted to the Connecticut Veterinary Medical Diagnostic Laboratory (CVMDL) during 2018–2019. Among 88 bats submitted to CVMDL, six brain samples (6.8%, 95% confidence interval: 1.6% to 12.1%) tested positive by direct fluorescent antibody test. RABVs were detected in big brown bats (Eptesicus fuscus, n = 4), a hoary bat (Lasiurus cinereus, n = 1), and an unidentified bat species (n = 1). Complete coding sequences of four out of six detected RABVs were obtained. In phylogenetic analysis, the RABVs (18-62, 18-4347, and 19-2274) from big brown bats belong to the bats EF-E1 clade, clustering with RABVs detected from the same bat species in Pennsylvania and New Jersey. The bat RABV (19-2898) detected from the migratory hoary bat belongs to the bats LC clade, clustering with the eleven viruses detected from the same species in Arizona, Washington, Idaho, and Tennessee. The approach used in this study generated novel data regarding genetic relationships of RABV variants, including their reservoirs, and their spatial origin and it would be useful as reference data for future investigations on RABV in North America. Continued surveillance and genome sequencing of bat RABV would be needed to monitor virus evolution and transmission, and to assess the emergence of genetic mutations that may be relevant for public health.

Functional Analyses of Peripheral Auditory System Adaptations for Echolocation in Air vs. Water

The similarity of acoustic tasks performed by odontocete (toothed whale) and microchiropteran (insectivorous bat) biosonar suggests they may have common ultrasonic signal reception and processing mechanisms. However, there are also significant media and prey dependent differences, notably speed of sound and wavelengths in air vs. water, that may be reflected in adaptations in their auditory systems and peak spectra of out-going signals for similarly sized prey. We examined the anatomy of the peripheral auditory system of two species of FM bat (big brown bat Eptesicus fuscus; Japanese house bat Pipistrellus abramus) and two toothed whales (harbor porpoise Phocoena phocoena; bottlenose dolphin Tursiops truncatus) using ultra high resolution (11–100 micron) isotropic voxel computed tomography (helical and microCT). Significant differences were found for oval and round window location, cochlear length, basilar membrane gradients, neural distributions, cochlear spiral morphometry and curvature, and basilar membrane suspension distributions. Length correlates with body mass, not hearing ranges. High and low frequency hearing range cut-offs correlate with basilar membrane thickness/width ratios and the cochlear radius of curvature. These features are predictive of high and low frequency hearing limits in all ears examined. The ears of the harbor porpoise, the highest frequency echolocator in the study, had significantly greater stiffness, higher basal basilar membrane ratios, and bilateral bony support for 60% of the basilar membrane length. The porpoise’s basilar membrane includes a “foveal” region with “stretched” frequency representation and relatively constant membrane thickness/width ratio values similar to those reported for some bat species. Both species of bats and the harbor porpoise displayed unusual stapedial input locations and low ratios of cochlear radii, specializations that may enhance higher ultrasonic frequency signal resolution and deter low frequency cochlear propagation.

Integrating Multiple Survey Techniques to Document a Shifting Bat Community in the Wake of White-Nose Syndrome

Abstract The long-term study of bat communities often depends on a diverse set of sampling methodologies that are chosen based on the species or habitat management priorities of the research project. Integrating the data from a diverse set of methodologies (such as acoustic monitoring and mist net sampling) would improve our ability to characterize changes in community structure or composition over time, such as one would expect following an emergent infectious disease such as white-nose syndrome. We developed a Bayesian state-space model to integrate these disparate data into a common currency (relative abundance). We collected both acoustic monitoring and mist net capture data over an 8-y period (2006–2014) to document shifts in the bat community in central New England, USA, in response to the onset of white-nose syndrome in 2009. The integrated data model shows a significant decline in the abundance of little brown bat Myotis lucifugus, northern long-eared bat Myotis septentrionalis, and hoary bat Lasiurus cinereus, and an increase in abundance of the eastern small-footed bat Myotis leibii and the eastern red bat Lasiurus borealis. There was no evidence for a change in abundance in the big brown bat Eptesicus fuscus since the onset of white-nose syndrome. The consistency of this model with regional estimates of decline over the same time period support the validity of our relative abundance estimate. This model provides the opportunity to quantify shifts in other communities where multiple sampling methodologies were employed, and therefore provides natural resource managers with a robust tool to integrate existing sampling data to quantify changes in community composition that can inform conservation and management recommendations.

Hepatic lipid signatures of little brown bats (Myotis lucifugus) and big brown bats (Eptesicus fuscus) at early stages of white-nose syndrome

White-nose syndrome (WNS) is an emergent wildlife fungal disease of cave-dwelling, hibernating bats that has led to unprecedented mortalities throughout North America. A primary factor in WNS-associated bat mortality includes increased arousals from torpor and premature fat depletion during winter months. Details of species and sex-specific changes in lipid metabolism during WNS are poorly understood and may play an important role in the pathophysiology of the disease. Given the likely role of fat metabolism in WNS and the fact that the liver plays a crucial role in fatty acid distribution and lipid storage, we assessed hepatic lipid signatures of little brown bats (Myotis lucifugus) and big brown bats (Eptesicus fuscus) at an early stage of infection with the etiological agent, Pseudogymnoascus destructans (Pd). Differences in lipid profiles were detected at the species and sex level in the sham-inoculated treatment, most strikingly in higher hepatic triacylglyceride (TG) levels in E. fuscus females compared to males. Interestingly, several dominant TGs (storage lipids) decreased dramatically after Pd infection in both female M. lucifugus and E. fuscus. Increases in hepatic glycerophospholipid (structural lipid) levels were only observed in M. lucifugus, including two phosphatidylcholines (PC [32:1], PC [42:6]) and one phosphatidylglycerol (PG [34:1]). These results suggest that even at early stages of WNS, changes in hepatic lipid mobilization may occur and be species and sex specific. As pre-hibernation lipid reserves may aid in bat persistence and survival during WNS, these early perturbations to lipid metabolism could have important implications for management responses that aid in pre-hibernation fat storage.

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.

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 2.6‐g sound and movement tag for studying the acoustic scene and kinematics of echolocating bats

Abstract To study sensorimotor behaviour in wild animals, it is necessary to synchronously record the sensory inputs available to the animal, and its movements. To do this, we have developed a biologging device that can record the primary sensory information and the associated movements during foraging and navigating in echolocating bats. This 2.6‐g tag records the sonar calls and echoes from an ultrasonic microphone, while simultaneously sampling fine‐scale movement in three dimensions from wideband accelerometers and magnetometers. In this study, we tested the tag on an European noctula Nyctalus noctula during target approaches and on four big brown bats Eptesicus fuscus during prey interception in a flight room. We show that the tag records both the outgoing calls and echoes returning from objects at biologically relevant distances. Inertial sensor data enables the detection of behavioural events such as flying, turning, and resting. In addition, individual wing‐beats can be tracked and synchronized to the bat's sound emissions to study the coordination of different motor events. By recording the primary acoustic flow of bats concomitant with associated behaviours on a very fine time‐scale, this type of biologging method will foster a deeper understanding of how sensory inputs guide feeding behaviours in the wild.

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.

Impacts of White-Nose Syndrome Observed During Long-Term Monitoring of a Midwestern Bat Community

Abstract White-nose syndrome (WNS) is an emerging fungal disease suspected to have infected Indiana caves in the winter of 2010–2011. This disease places energetic strains on cave-hibernating bats by forcing them to wake and use energy reserves. It has caused >5.5 million bat deaths across eastern North America, and may be the driving force for extinction of certain bat species. White-nose syndrome infection can be identified in hibernacula, but it may be difficult to determine whether bats in a particular area are affected if no known hibernacula exist. Thus, our aim was to use long-term monitoring data to examine changes in a summer population away from hibernacula that may be attributable to WNS effects during winter. We used capture data from a long-term bat-monitoring project in central Indiana with data from 10 repeatedly netted sites consistent across all reproductive periods. We modeled capture data by WNS exposure probability to assess changes in relative abundance of common species and reproductive classes as WNS exposure probability increases. We base exposure probability on a cokriging spatial model that interpolated WNS infection from hibernaculum survey data. The little brown bat Myotis lucifugus, the Indiana bat M. sodalis, and the tri-colored bat Perimyotis subflavus suffered 12.5–79.6% declines; whereas, the big brown bat Eptesicus fuscus, the eastern red bat Lasiurus borealis, and the evening bat Nycticeius humeralis showed 11.5–50.5% increases. We caught more nonreproductive adult females and postlactating females when WNS exposure probabilities were high, suggesting that WNS is influencing reproductive success of affected species. We conclude that, in Indiana, WNS is causing species-specific declines and may have caused the local extinction of M. lucifugus. Furthermore, WNS-affected species appear to be losing pups or forgoing pregnancy. Ongoing long-term monitoring studies, especially those focusing on reproductive success, are needed to measure the ultimate impacts of WNS.

Target shape perception and clutter rejection use the same mechanism in bat sonar.

Big brown bats (Eptesicus fuscus) emit frequency-modulated (FM) biosonar sounds containing two or more harmonic sweeps. Echoes from frontally located targets arrive with first and second harmonics intact, leading to focused delay images. Echoes from offside or distant objects arrive with the second harmonic relatively weaker (lowpass-filtered), leading to defocused images, which prevents their clutter interference effects (Bates et al. J Exp Biol 214:394-401, 2011). Realistic targets contain several glints at slightly different distances and reflect several echoes at correspondingly different delays. The bat registers the delay of the nearest glint's echoes in the time domain. The delays of echoes from the farther glints are registered in the frequency domain, from interference nulls in the spectrum. Lowpass-filtering of echoes directly affects the image of the nearest glint by defocusing the delay image. However, lowpass-filtering also is superimposed on the interference spectrum used to register the farther glints, which distorts the pattern of interference nulls, defocusing the farther glints inversely, in the spectral domain, before they are perceived as delays. Differences in blurring between time-domain and frequency-domain parts of images identifies separate computational paths to perceptually reconstruct objects and prevent interference from off-side or distant clutter.

Choice Experiments Demonstrate that Male Big Brown Bats (Eptesicus fuscus) Prefer Echolocation Calls of High Copulatory Females

It generally is accepted that bats emit ultrasonic vocalizations that function for echolocation purposes as well as for communication. We tested whether male or female big brown bats (Eptesicus fuscus) responded to variation in echolocation calls of the opposite sex in a manner that would suggest calls are used in a mating context. We presented 31 female and 10 male big brown bats with ultrasonic playbacks of differentially mating (i.e., high frequency copulators = HM versus low-frequency copulators = LM) individuals of the opposite sex. We measured 1) which side of the arena each subject selected first (HM versus LM), and 2) duration spent (seconds) on each side of the arena (HM versus LM). For both of these measures (i.e., first choice and duration) male subjects were more likely to select the echolocation calls of HM females, but the same respective tests determined that female subjects did not select echolocation calls of frequently copulating males over calls of infrequently copulating males. These r...

Patterns of parasite community dissimilarity: the significant role of land use and lack of distance‐decay in a bat–helminth system

Increasing community dissimilarity across geographic distance has been described for a wide variety of organisms and understanding its underlying causes is key to understanding mechanisms driving patterns of biodiversity. Both niche‐based and neutral processes may produce a distance decay relationship; however, disentangling their relative influence requires simultaneous examination of multiple potential drivers. Parasites represent a unique opportunity in which to study distance decay because community dissimilarity may depend on environmental requirements and dispersal capability of parasites as well also those of their hosts. We used big brown bats Eptesicus fuscus and their intestinal helminths to investigate: 1) independent contributions of geographic and environmental distances on dissimilarity of intestinal helminth component communities between populations of big brown bats; 2) which environmental variables best explained variation in community dissimilarity; and 3) whether similar patterns of decay with geographic or environmental distance were observed for within‐host population and within‐individual host parasite communities. We used compositional measures of community dissimilarity to examine how parasite communities may change with geographic distance and varying environmental conditions. Non‐spatial variables strongly influenced compositional parasite community dissimilarity over multiple community scales, and we observed little evidence for spatial processes such as distance decay. Environment surrounding roost sites better predicted helminth community dissimilarity than any other class of variables and landcover classes representing anthropogenic modification consistently explained variation in community structure. Our results indicate that human disturbance drives significant patterns of parasite community dissimilarity, most likely by changing the presence or abundance of intermediate hosts in an area.

A Comparison of Passive and Active Acoustic Sampling for a Bat Community Impacted by White-Nose Syndrome

Abstract In the summers of 2011 and 2012, we compared passive and active acoustic sampling for bats at 31 sites at Fort Drum Military Installation, New York. We defined active sampling as acoustic sampling that occurred in 30-min intervals between the hours of sunset and 0200 with a user present to manipulate the directionality of the microphone. We defined passive sampling as acoustic sampling that occurred over a 12-h period (1900–0700 hours) without a user present and with the microphone set in a predetermined direction. We detected seven of the nine possible species at Fort Drum, including the federally endangered Indiana bat Myotis sodalis, the proposed-for-listing northern bat M. septentrionalis, the little brown bat M. lucifugus, and the big brown bat Eptesicus fuscus, which are impacted by white-nose syndrome (WNS); and the eastern red bat Lasiurus borealis, the hoary bat L. cinereus, and the silver-haired bat Lasionycteris noctivagans, which are not known to be impacted by WNS. We did not detect two additional WNS-impacted species known to historically occur in the area: the eastern small-footed bat Myotis leibii and the tri-colored bat Perimyotis subflavus. Single-season occupancy models revealed lower detection probabilities of all detected species using active sampling versus passive sampling. Additionally, overall detection probabilities declined in detected WNS-impacted species between years. A paired t-test of simultaneous sampling on 21 occasions revealed that overall recorded foraging activity per hour was greater using active than passive sampling for big brown bats and greater using passive than active sampling for little brown bats. There was no significant difference in recorded activity between methods for other WNS-impacted species, presumably because these species have been so reduced in number that their “apparency” on the landscape is lower. Finally, a cost analysis of standard passive and active sampling protocols revealed that passive sampling is substantially more cost-effective than active sampling per hour of data collection. We recommend passive sampling over active sampling methodologies as they are defined in our study for detection probability and/or occupancy studies focused on declining bat species in areas that have experienced severe WNS-associated impacts.

Diversity and Distribution of Bats in the Northwest Territories

The occurrence of bats at the northern limit of their ranges in the Northwest Territories (NT), Canada, is not well documented. We provide information on the diversity and distribution of bat species in the NT by synthesizing available records. Before 2006, only 3 species of bats were known to occur in the NT: Little Brown Myotis (Myotis lucifugus), Northern Myotis (M. septentrionalis), and Hoary Bat (Lasiurus cinereus). Focused bat surveys as well as observations of bats reported by residents have added Long-eared Myotis (M. evotis), Long-legged Myotis (M. volans), Big Brown Bat (Eptesicus fuscus), and Silver-haired Bat (Lasionycteris noctivagans), for a total of 7 confirmed species, plus an additional species that is unconfirmed but suspected to occur (Eastern Red Bat, Lasiurus borealis). Range extensions for Little Brown Myotis, Hoary Bat, and Silver-haired Bat are reported. Both Little Brown Myotis and Northern Myotis are reproducing in the NT and are likely abundant in southern NT. Little Brown Myotis has been confirmed to overwinter in the NT and the northern limit of bat hibernation may be further north than previously supposed. Bats are widespread in the southern Central Plains region and gaps in occurrences likely reflect gaps in search effort. Nahanni National Park Reserve has high bat diversity and other parts of southwestern NT are suspected to have similarly high diversity, but have not yet been surveyed. There is evidence that the Eastern Shield region supports bats at relatively low densities. The northern distribution limit of bats in the NT is not known but is expected to occur in the Mackenzie Valley north of 62°N.

New Missouri County Records and Review of the Distribution and Disease Vector Potential of Ornithodoros Kelleyi (Arachnida: Ixodida: Argasidae) and Cimex Adjunctus (Insecta: Hemiptera: Cimicidae)

Abstract. The bat tick Ornithodoros kelleyi Cooley and Kohls (Arachnida: Ixodida: Argasidae) and eastern bat bug Cimex adjunctus Barber (Insecta: Hemiptera: Cimicidae) were collected from houses in Greene County, Missouri, that were previously infested by bats. Additional specimens of C. adjunctus were taken from a live big brown bat (Eptesicus fuscus (Palisot de Beauvois)) in Greene County and an evening bat (Nycticeius humeralis (Rafinesque)) in Webster County, Missouri. These records constitute only the third report of each species from the state, and the first from those counties. Distributional and host data for both species are summarized and presented. Distribution, feeding habits, and limited association with human habitations confer a low disease vector potential on both ectoparasites.

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.

Changes in spectrotemporal features of echolocation signals in multiple bat assemblages.

Echolocating bats face potential acoustical interference when flying and foraging near echolocating conspecifics. Quantifying changes in the signal structure of echolocation emissions between bats flying alone and within a larger group has proven difficult. Here, we use two new methodologies, an onboard radio telemetry microphone and a multiple microphone array to record the sounds of big brown bats (Eptesicus fuscus) flying alone and in small groups both in the laboratory and in the field. In a laboratory flight room, bats changed the ending frequency of their first harmonic when the conspecific with which they were paired emitted calls at a similar frequency. In the field, ending frequency and sweep shape were more variable among groups of bats flying together than among single bats compared to one another. The presence of other nearby bats did not have any effect on the timing of emissions or the interpulse intervals [Work supported by NIH, NSF, ONR, and JSPS.]