Bat Activity Research Articles

Modeling the power of acoustic monitoring to predict bat fatalities at wind turbines

AbstractLarge numbers of bats are killed at wind turbines worldwide. To formulate mitigation measures such as curtailment, recent approaches relate the acoustic activity of bats around reference turbines to casualties to extrapolate fatality rates at turbines where only acoustic surveys are conducted. Here, we modeled how sensitive this approach is when spatial distributions of bats vary within the rotor‐swept zone, and when the coverage of acoustic monitoring deteriorates, for example, with increasing turbine size. The predictive power of acoustic surveys was high for uniform or random distributions of bats. A concentration of bat passes around the nacelle or at the lower portion of the risk zone caused an overestimation of bat activity when ultrasonic microphones were pointed downwards at the nacelle. Conversely, a concentration of bat passes at the edge or at the top portion of the risk zone caused an underestimation of bat activity. These effects increased as the coverage of the acoustic monitoring decreased. Extrapolated fatality rates may not necessarily match with real conditions without knowledge of the spatial distribution of bats, particularly when the risk zone is poorly covered by acoustic monitoring, when spatial distributions are skewed and when turbines are large or frequencies of echolocating bats high. We argue that the predictive power of acoustic surveys is sufficiently strong for nonrandom or nonuniform distributions when validated by carcass searches and by complementary studies on the spatial distribution of bats at turbines.

Far from home: Bat activity and diversity in row crop agriculture decreases with distance to potential roost habitat

As demand for food increases, agricultural production is poised to increase dramatically. Pesticides are commonly used to maintain high crop yield, though they have several drawbacks, including reduced efficacy over time and harmful effects to human and ecosystem health. Bats are highly effective predators of crop pests and have great potential to reduce crop damage resulting from insects. However, few studies have investigated how pest control by bats might change over large expanses of continuous row crop agriculture, which is common in the midwestern USA. Agricultural landscapes offer few roosting opportunities and could be difficult for bats to traverse, which might affect the degree of ecosystem services provided by bats. We hypothesized that with increasing distance into uninterrupted row crop agriculture 1) bat activity would decrease and 2) bat species richness would decrease, but that these effects would be buffered when insect pest abundance is high. We deployed 50 acoustic bat detectors over 10 transects in east-central Illinois from July to September 2021. In each transect, we placed detectors on crop field edges at increasing distance from a large riparian corridor assumed to be frequented by bats. Bat activity was high across the landscape but declined by 56% from the forest edge to 4000 m into row crop agriculture, while bat diversity decreased by 34%. Pest abundance seemed to decrease overall bat activity but had no effect on bat diversity. These results indicate that bats, although able to have a large effect on crop pest reduction, might not be as efficient in suppressing crop pests in vast uninterrupted agricultural landscapes which offer scant roost availability. Our work will inform recommendations to landowners and private lands managers on ways to increase bat access to roosts and forest cover near agricultural areas, thereby enhancing the potential for bats to provide pest control services.

Traffic noise affects foraging behavior and echolocation in the Lesser Bulldog Bat, Noctilio albiventris (Chiroptera: Noctilionidae)

Urban noise, such as that of traffic, can affect the sensory capabilities in animals. Foragers acting optimally are expected to exploit feeding patches depending on the cost/benefit ratio, and some noises can cause increased foraging costs. We hypothesized that traffic noise affects foraging patch quality for aerial-insectivorous bats and predicted that there are measurable differences in their foraging activity and in their echolocation signals between nights with or without traffic noise. We tested these predictions in the Lesser Bulldog Bat, Noctilio albiventris, foraging over aquaculture fishponds, by recording bat activity on nights playing traffic noise and on traffic-sound free control nights. We measured foraging activity by counting the number of search passes and feeding buzzes made by the bats and measured several characteristics of echolocation signals. Foraging activity was higher during noisy nights than during control ones, probably due to the need of more time to obtain information about prey under noisy conditions. When exposed to traffic noise, the bats changed the spectral and temporal characteristics of echolocation signals. We suggest that exposure to traffic noise increases foraging costs for N. albiventris and posit that these bats continue foraging under noisy conditions because they can modulate their echolocation signals to obtain enough information.

Organic farming sustains bats in Mediterranean farmland

Organic agriculture is often deemed effective in conserving and promoting biodiversity, yet most studies have so far only focused on farmland in temperate areas and a few taxonomic groups, mainly birds and arthropods. Mediterranean agroecosystems host considerable biodiversity, and their wildlife likely delivers quantitatively important ecosystem services to agriculture, yet information is still limited. Here, we test the importance of organic farming and habitat structure for bat activity and richness in the Mediterranean. We disentangled the effects of organic vs. conventional management and habitat structure by adopting acoustic surveys and a matched-pair sampling design. Foraging bats preferred organic over conventional farming, with a scale-independent effect of local farm management on activity (but not richness), consistently across bat species and functional guilds. While fine-scale habitat structure had contrasting effects on bat species and guilds, the positive influence of linear landscape elements on bat activity was consistent and independent of management options. We highlight the key role of organic farming in preserving and promoting bat activity in agricultural areas, which brings the mutual benefit of sustaining bat conservation and emphasising the precious ecosystem services bats provide. To increase bat richness, however, appropriate management of landscape structure must be secured at larger geographical scales.

Brown fat activation demonstrated on FDG PET/CT predicts survival outcome.

The purpose of this study was to compare the survival of patients with and without BAT activity on FDG PET/CT. PET/CT exams from 3937 breast cancer patients were retrospectively reviewed for bilateral symmetric elongated FDG activity in the neck and chest, typical of BAT activation. A control group of age-matched (± 1year) breast cancer patients who underwent PET/CT the same week was also enrolled for comparison. Kaplan-Meier curves of progression-free survival (PFS) and overall survival (OS) for BAT positive patients and the control group were calculated. Further sub-analysis was performed to account for the hormonal changes associated with menopause. 2.0% (80/3937) of the breast cancer patients who underwent PET/CT demonstrated BAT activation, and 80 additional patients were analyzed for comparison as the group without BAT activity. Mean follow-up was 76months (range 1-225months). There were 4 recurrences in the BAT group, compared to 12 in the control. The mean PFS for the BAT group was 127months, which was significantly lower than the mean PFS of 180months in the control (p = 0.047). Sub-analysis of premenopausal women again showed longer PFS for the BAT group (129 vs. 196months, p = 0.095) while no difference was found in postmenopausal women (mean 102 vs. 135months, p = 0.360). Presence of BAT activity was also a significant predictor variable for PFS on Cox regression. Patients with BAT activity showed longer progression-free survival than those without, emphasizing the need for further evaluation of its role in metabolism, treatment response, tumor microenvironment and long-term prognosis.

The influence of forest management practices on seasonal bat species occurrence and activity at the Kisatchie National Forest in Louisiana, USA

In the southeastern United States, where forests are the primary land cover type, understanding how forest stand characteristics and forest management practices influence bat distributions is critical for bat conservation and management. We deployed passive acoustic monitors to record bat calls at sites representing six forest types at the Kisatchie National Forest in central Louisiana during two winter (January–February 2020 and December 2020–February 2021) and two summer (June–August 2020 and 2021) periods. We also collected environmental data at the landscape and local scales to help explain patterns in bat species occurrence. We detected big brown bats (Eptesicus fuscus), eastern red/Seminole bats (Lasiurus borealis/L. seminolus), Myotis species, tricolored bats (Perimyotis subflavus), Mexican free-tailed bats (Tadarida brasiliensis), and hoary bats (Aeorestes cinereus) during both periods, and additionally detected evening bats (Nycticeius humeralis) during the summer. We observed seasonal differences in habitat use, and found that three bat species were more active during the summer in pine forests with group selection harvest, pine forests managed for red-cockaded woodpeckers (Leuconotopicus borealis), and pine forests that were clearcut within five years of our study when compared to unmanaged pine forests, thinned pine forests, and bottomland hardwood forests. Contrary to other studies, we found that the predicted probability of occupancy decreased with increasing proximity to riparian areas for four bat species, which could reflect the complex understory vegetation conditions that we observed along the riparian corridors in our study area. Our research identified forest characteristics and management practices that promote bat species diversity and activity in central Louisiana and demonstrated that pine forests with open understories and small openings in the canopy provide important foraging habitat for bats that occur in our study area and possibly other regions in the southeast.

Bat Assemblages Are Shaped by Land Cover Types and Forest Age: A Case Study from Eastern Ukraine

Eastern European broadleaved forests north of the 50th degree of latitude serve as a core breeding area for most migratory bat species wintering in Eastern and Central Europe. The southern border of this region has faced an increase in clear-cutting intensity in recent decades. We conducted a standardized mist-netting survey on eleven heterogeneous oak forest plots in order to assess how land cover types and forest age affect abundance, diversity and the breeding of bats. We found that abundance indices and species richness increased from upland plots surrounded by agricultural lands to riverine or waterside plots with high forest cover. Particularly large mature forests older than 90 years positively affected the breeding activity of bats, their abundance indices and overall species richness. Regarding species associations with specific habitats, we found that Myotis brandtii, Nyctalus leisleri and Pipistrellus pygmaeus were mainly found in mature deciduous forest stands, while Plecotus auritus appeared to be the only species tolerating clearcuts and young stands. Forest-dwelling species such as Nyctalus noctula and Pipistrellus nathusii were additionally associated with water habitats. Thus, the combination of mature forests and water sources is essential in shaping Eastern European assemblages of forest bat species.

Batting for rice: The effect of bat exclusion on rice in North-East India

Insectivorous bats are gaining increasing attention for their potential as biological agents of pest suppression. Studies around the world have demonstrated their tendency to track and hunt agricultural pests over time and space, and thus to have a positive impact on reducing plant damage and protecting yield of agricultural crops. We documented the effect of insectivorous bats on the health and yield of a rice crop in Assam, India. Using six sets of paired experimental and control plots (of which five were analysed), where bats were selectively excluded from the experimental plots, we collected two measures of plant damage and one measure of total yield to assess the impact of bats on the crop. In parallel, bat activity at the six sites was recorded over the rice growing season using passive acoustic recorders. Our results show that the exclusion of insectivorous bats causes an increase in the degree of defoliation suffered by rice plants. We also report non-significant differences in the degree of yellowing of rice and of the total yield between the experimental and control plots. Bat activity levels showed a mono- or bi-modal peak in activity over the growing season, which broadly tracked the maturity of rice, a pattern also seen in many insect pests. Our results strongly suggest that bats have suppressive impact on pest action in rice fields. The general trend in activity levels, as well as the significant difference in plant damage, would indicate that bats are hunting insect pests and that the non-significant difference in final yield was likely the result of methodological limitations. These findings suggest that bats add significant ecological and economic value to Indian rice ecosystems and hold great potential to be used in integrated pest management (IPM) strategies aimed at suppressing pests.

How different farming practices influence the activity of insectivorous Neotropical bats

Recent bioacoustic studies have shown different responses of insectivorous bats to native habitat loss. We examined the activity and species/sonotypes composition of aerial insectivorous bats present in a human-modified karst landscape in Southeast Brazil, characterized by the presence of semideciduous forest, pastures and Eucalyptus globulus monocultures. Using ultrasonic detectors, we investigated activity and identified bat species and/or sonotypes in the three habitat types. We compared the activity (as a surrogate for abundance) and composition of species/sonotypes present and used Generalized Linear Models to investigated whether canopy density, understory density and food availability influence the response of bats in these habitat types. Our main results demonstrate that the variables general passes and species/sonotype richness did not differ significantly between forest and pasture, however, both variables in these two environments differed significantly from the values ​​found for eucalyptus. We conclude that, in the studied agropastoral landscape, pastures interspersed with forest areas can be used by aerial insectivorous bats during foraging. However, we also found evidence that eucalyptus monocultures, not yet mature and without an understory, have a negative impact on the species/sonotype richness and activity of Neotropical aerial insectivorous bats.

Fall and winter activity of two bat species in response to winter flooding and decreasing temperature

Mature trees with hollow cavities are an important resource as roost sites for Rafinesque’s big-eared bats (Corynorhinus rafinesquii) and Southeastern myotis (Myotis austroriparius). Southern populations of these bats typically remain active in the winter (ca. November-March) but seasonal flooding in bottomland forests may prevent them from exiting their roosts. Our objective was to determine if and how seasonal flooding affects activity and roost-switching patterns of these species in Cache River National Wildlife Refuge, Arkansas. In October-December of 2016 and 2017, we radio-tracked 21 Rafinesque’s big-eared bats and 17 Southeastern myotis to 33 and 42 confirmed roost trees, respectively. Tree species, cavity type (e.g., basal cavity), and GPS coordinates were recorded for each confirmed roost tree. Additionally, bat activity, temperature, and water level were monitored using acoustic devices, iButton data loggers, and gauges, respectively. Although both species remained active, some of their roosting habits changed in response to decreasing temperature (from ca. 30 ℃ to −6 ℃ at sunset) rather than flooding. Notably, Southeastern myotis used mainly water tupelo in the fall (86 %, n = 14 trees), but roosted in varied hardwood species located in adjacent floodplain forests in the winter. With adverse weather and higher water levels, behavioral changes exhibited by these species may coincide with changing priorities from foraging to avoiding seasonally rising flood waters, maintaining homeostatic balance, or breeding and social interaction. In conclusion, when creating or revising their management plans, managers will need to consider the variety of roosts that these species require at different times of the year.

Native pedunculate oaks support more biodiversity than non-native oaks, but non-native oaks are healthier than native oaks: A study on street and park trees of a city

Trees in cities provide multiple ecosystem services. However, simultaneously ensuring healthy trees with high habitat diversity can be challenging in a harsh urban environment. We compared health, microhabitats, and bat activities between native (Quercus robur L.) and non-native (Quercus rubra L.) oaks growing in different urban habitats (street vs. park) in Karlsruhe, southwestern Germany. We randomly selected 167 oak trees with a diameter at breast height (DBH) >20 cm across the city from Urban Tree Registrar. We performed tree health assessment, dendrometric, and microhabitat inventory. We recorded the four-day bat activities on 45 native and non-native oaks with acoustic loggers installed on the trees. We found that non-native oaks were healthier than native oaks but provided less abundance and richness of microhabitats. Tree size (positive effect) and pruning (negative effect) strongly influence microhabitat richness and abundance. In addition, park trees hosted significantly more microhabitats than street trees. We recorded the activities of 9 bat species from 4 genera. Pipistrellus bats were more active in park trees than street trees. Long-eared bats (Plecotus) were more active near the native than non-native oaks. Bats are likely favored by microhabitats such as fork split, lightning scar, and woodpecker “flute” that are more common in less healthy trees. We conclude that non-native red oak can be planted alongside streets, where the conditions are harsher than in parks to better adapt to climatic changes and stay healthy with less maintenance. The preservation of native pedunculate oak trees, especially within parks, is paramount for urban biodiversity conservation because of their potential to provide microhabitats and supporting bats.

Advances of optical miniscopes for in vivo imaging of neural activity in freely moving animals.

To study neural mechanisms of ethologically relevant behaviors including many social behaviors and navigations, optical miniscopes, which can be carried by the model animals, are indispensable. Recently, a variety of optical miniscopes have been developed to meet this urgent requirement, and successfully applied in the study of neural network activity in free-moving mice, rats, and bats, etc. Generally, miniature fluorescence microscopes can be classified into single-photon and multi-photon fluorescence miniscopes, considering their differences in imaging mechanisms and hardware setups. In this review, we introduce their fundamental principles and system structures, summarize technical advances, and discuss limitations and future trends, for in vivo imaging of neural activity in freely moving animals.

Insectivorous Bats in Eastern Mediterranean Planted Pine Forests—Effects of Forest Structure on Foraging Activity, Diversity, and Implications for Management Practices

Bats are primarily forest mammals and forest structure may affect their communities through the level of vegetation clutter. Pine plantations are typically even-aged managed forests that lack structural complexity. However, an understory layer can enhance the heterogeneity of these forests, making them suitable for several animal taxa. We hypothesized that species composition, richness, and foraging activity of insectivorous bats in pine plantations vary according to forest structure, specifically with the density of the understory. We measured pine density, Diameter at Breast Height (DBH), canopy closure, and vegetation cover of 29 pine (Pinus halepensis) plantations of the Judean Lowlands, Israel, and collected acoustic data on resident bats. We found that bat species richness and total activity increased in forests with large tree DBH and dense shrubs. Cluttered-habitat species foraged preferentially in forests with large tree DBH and high pine density, while open-habitat species preferred forests with well-developed canopies and dense shrubs. Pipistrellus pipistrellus and Eptesicus serotinus foraged in mature forests with well-developed bushes and these species are endangered in Israel. We conclude that mature planted pine forests with a well-developed under-canopy are suitable foraging grounds for insectivorous bats. Management plans for planted pine forests should consider our findings to support bat populations, including rare and endangered species.

Applying mobile acoustic surveys to model bat habitat use across sinuous routes

AbstractMobile acoustic surveys allow estimates of overall bat activity, relative abundance, and species richness across large areas. Protocols for estimating relative abundance recommend using non‐sinuous routes to ensure individual bats are only recorded once. We conducted mobile acoustic surveys along 12 sinuous routes in the mountainous terrain of northeastern Tennessee. Our objectives were to 1) determine if more calls were recorded in sinuous segments of mobile survey routes, thus violating assumptions of mobile surveys, and 2) analyze mobile transect data to assess bat habitat use. To test for effects of road sinuosity, we divided transects into ~1.6‐km segments, calculated a sinuosity value, and summed the number of identified call files recorded for each segment. Using generalized linear models, we determined sinuosity did not affect the number of identified acoustic files. We assessed habitat use for 3 bat phonic groups (Low, Mid, Myotis), comparing 10 models with temporal detection and spatial occupancy covariates. Date were informative for all phonic groups. Low and mid‐frequency bats were more likely to be detected on later survey dates within the summer, whereas Myotis bats had a higher probability of detection earlier within the season. As proportion of agriculture around the transect segment increased, probability of use by low‐frequency bats decreased. The proportion of forest surrounding the transect segment had a positive effect on use by Myotis bats. No environmental covariates were informative regarding mid‐frequency bats. We conclude that mobile acoustic surveys are an efficient method for gathering data on habitat use by bats. We recommend following guidelines set forth by the North American Bat Monitoring Program for mobile acoustic surveys but note that sinuosity of the route did not affect the number of calls recorded in our study; thus, we suggest that sinuous roads in mountainous terrain are appropriate for mobile acoustic transects.

Cold Stress Protocol In Brown Adipose Tissue Activation In Obese Men

PURPOSE: To measure the activation of brown adipose tissue by cold stress protocol in obese men. METHODS: 24 male military from Brazilian Army were evaluated (38.5 ± 1.8 years, BMI:30.7 ± 2.9 kg/m2,body fat:31.0 ± .2%). The maximum and medium supraclavicular temperature (TScvMax/TScvMed) from right/left sides and the maximum and medium sternum temperature (TStrMax/TStrMed) were register using the infrared camera E75 FLIR®, in two moments. First, volunteers remain 30 min in a thermoneutral environment (22.6 ± 0.2 °C) for thermalization. Second, hands were submerged in a container with ice water at the temperature of 13.0 ± 0.4 °C, during 5 min after. The body composition was evaluated using double X-ray absorptiometry. Kolmogorov-Smirnov normality test applied and confirmed parametric approach. The data were analyzed by SPSS® 25.0, running Student’s t-test two paired samples. The effect-size (Cohen's d) was calculated with GPower software. Significance level at p < 0.05. The images were analyzed using FLIR Tools® software. RESULTS: On the TScvMax was observed a significant increase on the right side from 33.6 ± 0.4 °C to 34.1 ± 0.6 °C (p < 0.001;d = 0.787) and on the left side 33.3 ± 0.6 °C to 34.0 ± 06.4 °C (p < 0.001;d = 0.787). On the TScvMed also was observed a significant increase on the right side from 32.8 ± 0.4 °C to 33.4 ± 0.6 °C (p < 0.001;d = 0.787) and on the left side 32.5 ± 0.5 °C to 33.1 ± 0.5 °C (p < 0.001;d = 0.787). But it was not observed in the control region (Sternum) where there was no BAT for TMax and TMed (p = 0.923 and p = 0.869), respectively. CONCLUSIONS: Cold stress protocol proved to be effective in BAT activation, increasing the temperature in the supraclavicular region for the obesity men group. This protocol ican be used in the clinical evaluation. It is suggested that in future studies other protocols with less time of exposure to the cold be studied, thus reducing the discomfort of the evaluated individual.

How do we sleep while our beds are burning? Impacts of the 2019–20 mega-fires on a rainforest dependent species – the Golden-tipped Bat Phoniscus papuensis

ABSTRACT The Australian summer of 2019/20 was impacted by megafires of a magnitude and severity never previously recorded. Whilst low severity fire has positive benefits for increased insectivorous bat activity and diversity, little information is available on the impact on rainforest specialised clutter dependant species such as the Golden-tipped Bat Phoniscus papuensis. Our aims were to assess the effects of fire on occupancy of habitat across the geographic range of P. papuensis in NSW, to determine the smaller scale effects of fire on use of diurnal roosts in rainforest through radio tracking and to trial the use of artificial structures to temporarily increase roost availability in burnt habitat. We observed that widespread fire encroaching on rainforest has a negative association with occupancy by P. papuensis, with this metric ~78% lower than in unburnt forest. In burnt areas, P. papuensis preferentially used unburnt refugia for their roosting sites in suspended bird nests and the loss of these habitat structures likely contributes to the disappearance of P. papuensis from the landscape. Artificial roosts were not used in the short-term (&amp;lt; 2 years post fire) and do not appear to be a feasible management tool. With the increasing frequency and extent of wildfires the most important factor for P. papuensis to persist in the landscape into the future is the protection of its habitat through ensuring sensitive management of large tracts of connected rainforest to help buffer against the encroachment of future mega-fires.

Cooling-activated dorsomedial hypothalamic BDNF neurons control cold defense in mice.

BDNF and its expressing neurons in the brain critically control feeding and energy expenditure (EE) in both rodents and humans. However, whether BDNF neurons would function in thermoregulation during temperature challenges is unclear. Here, we show that BDNF neurons in the dorsomedial hypothalamus (DMHBDNF ) of mice are activated by afferent cooling signals. These cooling-activated BDNF neurons are mainly GABAergic. Activation of DMHBDNF neurons or the GABAergic subpopulations is sufficient to increase body temperature, EE, and physical activity. Conversely, blocking DMHBDNF neurons substantially impairs cold defense and reduces energy expenditure, physical activity, and UCP1 expression in BAT, which eventually results in bodyweight gain and glucose/insulin intolerance. Therefore, we identify a subset of DMHBDNF neurons as a novel type of cooling-activated neurons to promote cold defense. Thus, we reveal a critical role of BDNF circuitry in thermoregulation, which deepens our understanding of BDNF in controlling energy homeostasis and obesity.

Seasonal Activity Patterns of Bats in High-Elevation Conifer Sky Islands

In the southern Appalachian Mountains of the southeastern USA, bat communities in high-elevation habitats tend to be relatively under-surveyed. High-elevation habitats may provide important habitat to certain species (i.e., migratory tree bats), and may serve as climate refugia during droughts or high temperatures. We conducted an opportunistic acoustic survey of bat communities in ten survey areas in high elevation (1,585–1,920 m a.s.l.) montane Picea rubens (red spruce)-Abies fraseri (Fraser fir) forest in the southern Appalachian Mountains of western North Carolina. In each survey area, we randomly placed three full spectrum acoustic detectors (N = 30) during three seasons (spring, summer and fall) in 2015. We deployed each detector for two five-day periods during each season (n = 900 survey nights). Although we detected seven bat species/groups during the surveys, 73% of echolocation files were attributed to Lasiurus cinereus (hoary bat) and Lasionycteris noctivagans (silver-haired bat). Generally rare in the Appalachians and typically present only at low densities in the summer at mid- and low-elevations, both species were detected at all sites during all seasons. Overall, mean nightly activity of bats was higher in the summer than the spring or fall. We observed 3.7–5 times greater activity of L. cinereus in spruce-fir forests during the summer compared to spring and fall, whereas L. noctivagans had 1.3–5 times more activity in the summer compared to other seasons. After accounting for precipitation events, our finite mixture models showed that season, temperature, elevation, and canopy height influenced L. cinereus activity, whereas season and temperature affected L. noctivagans activity. Our observations suggest that high-elevation spruce-fir forests are providing summer foraging and possibly day-roosting habitat of tree bats not previously documented this far south in North America.

Daily, Seasonal and Inter-Annual Variation in Activity Within a Common Pipistrelle Swarming Site and Hibernaculum

Seasonal swarming by bats in underground sites in late summer and early autumn is increasingly understood to play a vital role in their life-cycle, relating both to nuptial activity and to the use of swarming sites as hibernacula. The common pipistrelle (Pipistrellus pipistrellus) is a largely commensal species in which seasonal swarming often occurs in built structures, which have been hypothesised to serve as mass hibernacula during the coldest part of the winter. A number of detailed studies of P. pipistrellus swarming sites have recorded year-round patterns of activity, as well as the demographic make-up of the visiting bats, but there has been relatively little study of overnight patterns of activity, or how swarming interacts with weather conditions at a variety of scales. This study uses auditory monitoring data, recorded continuously over a 27 month period in a P. pipistrellus swarming site within a built structure in northern England, to derive a detailed phenology of bat activity within the site, and uses generalised additive modelling to explain daily variation in activity in terms of seasonal trends modified by fluctuating weather conditions. Results suggest that cool conditions delay the onset of swarming in spring and late summer, and can suppress swarming behaviour even at the height of the swarming period, leading to a pronounced pulse of activity when temperatures rise, and the extension of activity into mid-Autumn. Roosting also occurred at the study site during the swarming period, and was associated with significant flying during the day in warm temperatures, which may reflect a search for cooler roosting locations. Overnight activity occurred throughout the hibernation period, but little evidence emerged for an influx of bats to a mass hibernaculum at the start of the winter.

NEW RECORDS ABOUT THE DIVERSITY, DISTRIBUTION, AND SEASONAL ACTIVITY PATTERNS BY BATS IN YUKON AND NORTHWESTERN BRITISH COLUMBIA

The bat fauna of northwestern Canada remains poorly known, principally owing to a lack of dedicated surveys across this vast region. To better assess the diversity of bats in the region, we compiled records from several acoustic survey projects and capture sessions whose purpose was to inventory bats in Yukon and northwestern British Columbia (BC) from 2013 to 2018. During our surveys we obtained the 1st apparent acoustic records for Yuma Myotis (Myotis yumanensis), Californian Myotis (M. californicus), Long-eared Myotis (M. evotis), Silver-haired Bat (Lasionycteris noctivagans) and Eastern Red Bat (Lasiurus borealis) from this region. We also captured 2 Long-eared Myotis in northwestern BC. Additionally, our surveys provided range extensions of Northern Myotis (M. septentrionalis), Long-legged Myotis (M. volans), and Hoary Bat (Lasiurus cinereus). Finally, by deploying bat detectors in late autumn, and in some cases throughout the winter, we provide data about seasonal patterns for bat activity in some locations, revealing that bats in northwestern BC may be active as late as 29 October and emerge as early as 30 March, a pattern similar to that observed in southern BC. By combining data from several disparate surveys, conducted for different reasons by different researchers, we were able to provide a fuller picture of the bat fauna of this vast region. Our data provides further evidence that the bat fauna of northwestern Canada is richer than previously documented.