Bat Activity Research Articles

Forest bat activity declines with increasing wind speed in proximity of operating wind turbines

The increasing use of onshore wind energy is leading to an increased deployment of wind turbines in structurally rich habitats such as forests. Forest-affiliated bats, in turn, are at risk of colliding with the rotor blades. Due to the legal protection of bats in Europe, it is imperative to restrict the operation of wind turbines to periods of low bat activity to avoid collisions. However, bats have also been observed to avoid wind turbines over several hundred meters distance, indicating a displacement that cannot solely be explained by modifications to the habitat. This avoidance suggests a displacement of bats by indirect factors related to wind turbine operation, e.g., wake turbulences and noise emissions. Therefore, we investigated whether the activity of forest-affiliated bats is influenced by operation mode (on/off) under variable wind conditions along transects from 80 to 450 m distance to wind turbines. We divided recordings by foraging guild, i.e., either narrow-space (Myotis, Plecotus), edge-space (Pipistrellus, Barbastella), or open-space foraging bats (Nyctalus, Eptesicus, Vespertilio), and analyzed the effects of wind turbine operation and wind speed on the recorded bat guild activity with mixed effects models. The acoustic activity of narrow-space foraging bats decreased by 77% with increasing wind speed when wind turbines were operating, while bat activity remained unaffected by wind speed when turbines were not operating. This was neither observed for open-space foraging bats nor for edge-space foraging bats, and neither wind turbine operation nor wind speed (ranging between 0 – 4 m/s at 10 m height above ground) were found to affect bat activity when considered alone. Wind turbine noise emissions are known to increase with rotor speed and consequently, wind speed, thus presenting a likely explanation for the interactive negative effect of turbine operation and wind speed specifically on noise-sensitive narrow-space foraging bats. To understand potential ecological long-term consequences for bat populations in forest areas with wind turbines and to design effective conservation measures, future research should focus on disentangling the effects of different disturbances related to turbine operation.

Patterns of Florida Bonneted Bat Occupancy at the Northern Extent of Its Range

Abstract The Florida bonneted bat Eumops floridanus is a rare, endemic bat of South Florida that roosts in woodpecker cavities and anthropogenic structures such as roofing tiles, chimneys, and bat houses. The northernmost occurrences of the bonneted bat are from mature pine forests at the Avon Park Air Force Range, Florida. We used ultrasonic acoustic recorders to understand bonneted bat activity and habitat occupancy. We modeled occupancy using a hierarchical Bayesian analysis and included site- and time-specific covariates of detection probability and site-specific covariates of occupancy. Probability of detection was low throughout Avon Park Air Force Range but increased with Julian date. In most habitats, occupancy was poorly estimated, except for flatwood mature pinelands where occupancy was low (0.23 ± 0.06). As distance from red-cockaded woodpecker colonies increased, occupancy decreased (β = −1.19 ± 0.26 SD). At the northernmost extent of the range, and throughout much of the historic range, increasing the expanse of mature, fire-maintained forest systems will increase habitat for the bonneted bat and lead to faster population recovery.

Succinate Enhances Lipolysis and Decreases Adipocytes Size in Both Subcutaneous and Visceral Adipose Tissue from High-Fat-Diet-Fed Obese Mice.

Obesity is a risk factor for many chronic diseases related to the overexpansion of adipose tissue during obesity, leading to metabolic dysfunction and ectopic lipids. Previous studies reported a close relationship between succinate and obesity and its co-morbidities, and studies have also reported on its anti-obesity potential. To confirm its efficacy in obesity interventions, we supplemented mice with obesity induced by a high-fat diet with succinate (1.5% m/v in drinking water) for 11 weeks without changing the diet. After succinate supplementation, the changes in body weight, adipose tissue deposition, glucose tolerance, energy expenditure and lipid metabolism were evaluated. It was found that succinate supplementation significantly decreased subcutaneous adipose tissue (HFD: 4239.3 ± 211.2 mg; HFD-SA: 3268.9 ± 265.7 mg. p < 0.05), triglyceride contents (decreased by 1.53 mmol/g and 0.39 mmol/g in eWAT and ingWAT, respectively, p < 0.05) and NEFA (decreased by 1.41 μmol/g and 1.31 μmol/g in eWAT and ingWAT, respectively, p < 0.05). The adipocytes' sizes all significantly decreased in both subcutaneous and visceral adipose tissue (the proportion of adipocytes with diameters larger than 100 μm in eWAT and ingWAT decreased by 16.83% and 11.96%, respectively. p < 0.05). Succinate significantly enhanced lipolysis in adipose tissue (eWAT: Adrb3, Hsl and Plin1; ingWAT: Hsl and CPT1a; p < 0.05), whereas the expression of lipogenesis-related genes remained unchanged (p > 0.05). Succinate supplementation also enhanced the activity of BAT by stimulating the expression of Ucp1 and Cidea (p < 0.05). Our results reported that succinate has a potential beneficial effect on obesity pathogenesis but cannot efficiently decrease bodyweight.

Unleashing the power of Bat optimized CNN-BiLSTM model for advanced network anomaly detection: Enhancing security and performance in IoT environments

The growth of IoT (Internet of Things) devices has revolutionized several industries and brought about novel security threats. Recognizing network anomalies that may point to malicious activity or system flaws is a major issue. Traditional anomalous identification methods frequently need to catch up when dealing with the special traits of IoT environments, including resource limitations and changing network behavior. This paper introduces an innovative approach, the Bat-optimized CNN-BiLSTM model, to enhance the security and efficiency of IoT environments. This model combines the strengths of Convolutional Neural Networks (CNNs) for spatial analysis and Bidirectional Long Short-Term Memory (BiLSTM) networks for capturing temporal patterns, thus effectively representing time and space trends in IoT data. To optimize its performance further, researchers have leveraged the Bat algorithm, inspired by natural behaviors, to fine-tune the model. This program effectively searches for the best network anomaly detection parameters by imitating the echo activity of bats. Researchers want to increase detection accuracy by lowering false positives and false negatives using the Bat algorithm to enhance the CNN-BiLSTM model. The experimental findings show that the Bat-optimised CNN-BiLSTM model beats the state-of-the-art anomaly detection methods with 99.43% accuracy and efficiency.

Artificial light affects foraging behavior of a synanthropic bat.

Artificial light at night has been considered an emerging threat to global biodiversity. However, the impacts of artificial light on foraging behavior in most wild animals remain largely unclear. Here, we aimed to assess whether artificial light affects foraging behavior in Asian parti-colored bats (Vespertilio sinensis). We manipulated the spectra of light-emitting diode (LED) lighting in a laboratory. Using video and audio recording, we monitored foraging onset, total foraging time, food consumption, freezing behavior (temporary cessation of body movement), and echolocation vocalizations in triads of bats under each lighting condition. Analyses showed that the foraging activities of experimental bats were reduced under LED light. Green, yellow, and red light had greater negative effects on bats' foraging onset, total foraging time, and food consumption than white and blue light. LED light of different spectra induced increased freezing time and echolocation vocalizations in captive bats, except for the white light. The peak wavelength of light emission correlated positively with freezing time, estimated echolocation pulse rate (the number of echolocation pulses per minute), and foraging onset, but negatively with total foraging time and food consumption. These results demonstrate that artificial light disturbs foraging behavior in Asian parti-colored bats. Our findings have implications for understanding the influencing mechanism of light pollution on bat foraging.

Bats as indicators of ecological resilience in a megacity

AbstractUrbanization has transformed more than 50% of the land area and brought the emergence of a new humanized-based ecosystem. In answer to this, urban systems have looked for become resilient. Thus, urban landscapes must enhance their resilience capacities; robustness, adaptability, and transformability. However, there is a necessity of a well performing and easy gathering indicators. In this paper, we propose that bats are a good indicator of city’s capacity to be resilient. We used bat permanence, species diversity, and activities to analyze Mexico City resilience capacities. We used citizen science to register bat sounds around the city. From these data we identified bat species and two main activities: passes and hunting buzzes. Data showed that the east and center area of the city had the lower species richness and relative abundance, while south was the richest. This diversity patterns were in response to different habitat characteristics, mainly those related to landscape. However, activities and permanence were strongly related with human presence. The bat permanence modeled, indicated that bat community structure could be shaped under changing scenarios. Due to their differential sensitivity bats are good indicators of habitat changes in urban landscapes. Cities seeking resilience should perform planned-habitat management to achieve a bat-friendly status and promote the ecosystem services that bats can provide.

Far-reaching displacement effects of artificial light at night in a North American bat community

Artificial light at night (ALAN) is a global pollutant that disrupts circadian rhythmicity and a broad range of physiological processes and behaviors in animals. However, ALAN sensitivity can vary greatly even among closely related species and urgently needs study for much of the world’s nocturnal wildlife, including bats. While an increasing number of bat species have recently been assessed for light tolerance, the spatial extent of ALAN’s influence on bats has received little attention. This information need is a barrier to the protection of bats from ALAN in land-use planning and policy, and the development of best practices that effectively buffer bat habitat from light trespass. To help address this information gap for North America, we experimentally tested the distances up to which ALAN affects presence and activity of light-averse little brown bats (Myotis lucifugus) and big brown bats (Eptesicus fuscus), and the composition of a foraging bat assemblage in Connecticut, USA. We used three residential-scale, white, LED floodlights to expose bat foraging habitat to ALAN and compared acoustic activity of bats at distances of 0, 25, 50, and 75 m from the lights between nights when the lights were on versus off. Little brown bats were present on significantly fewer light than dark nights at every distance. Lighting significantly reduced little brown bat activity overall and at the farthest location from the lights (75 m), where it was only 43% of dark-night activity despite < 1 lx of illuminance. Presence of big brown bats was not significantly affected at any distance. Big brown bat activity on light nights averaged 48–75% of dark-night activity at each distance but was significantly lower only at 0 m. As expected, lighting had no effect on eastern red (Lasiurus borealis) or hoary bat (L. cinereus) presence or activity. Community composition on dark and light nights had an average dissimilarity of 38% and significantly differed at 0 m and 25 m. We conclude the type of ALAN we studied has a disturbance radius of at least 75 m for the little brown bat and up to 25 m for the big brown bat, with a resulting influence on community composition for up to 50 m. Cumulative habitat loss for the imperiled little brown bat caused by ALAN could therefore be substantial. We urge planners and natural resources regulators to consider these footprints when evaluating indirect impacts to bat habitat from current and future sources of ALAN across these species’ ranges.

Bats (Chiroptera) of spruce forests in the Ukrainian Carpathians

Bat communities in monoculture spruce plantations (Skolivski Beskydy NNP, Gorgany (NNP Syniohora) and Chornohora areas) and spruce forests of the upper mountain forest belt (Verkhovynskyi NNP, Karpatskyi NNP) were studied by recording echolocation calls to assess the importance of such ecosystems for this group of animals. 11 species were recorded at the sample plots: Northern bat Eptesicus nilssonii, Serotine bat Eptesicus serotinus, Brand’s bat/Whiskered bat Myotis brandtii/mystacinus, Daubenton’s bat Myotis daubentonii, Greater mouse-eared bat Myotis myotis, Common noctule Nyctalus noctula, Brown long-eared bat Plecotus auritus, Nathusius’s bat Pipistrellus nathusii, Common pipistrelle Pipistrellus pipistrellus, Soprano pipistrelle Pipistrellus pygmaeus, Parti-coloured bat Vespertilio murinus. According to the degree of dominance (total number of registered calls), E. nilssonii was the most numerous (32.7%). M. mystacinus/brandtii (25.6%) and P. nathusii (18.9%) were somewhat less numerous. According to the spatial distribution (presence in the sample plots), only the pair M. mystacinus/brandtii was detected in all the studied plots. Of the other species, E. nilssonii (58.8%) and P. nathusii (41.2%) were most frequently represented. For the sibling species M. mystacinus/M. brandtii no special habitat requirements were found, but the high frequency of their observations in all ranges of forest biotopes shows them as typical "forest". The dominance of E. nilssonii in spruce forests confirms that this species mainly uses semi-boreal coniferous forests in the Central Europe. The highest value of Shannon's biodiversity index was found in spruce forests of lower altitudes, Skolivski Beskydy NNP (H' = 1.616) and Syniohora NNP (H' = 1.627). Probably, coniferous forests at lower altitudes can be more favourable foraging biotopes for representatives of populations that are not topically associated with such forests: P. pygmaeus, P. pipistrellus, V. murinus, N. noctula. The observed level of nocturnal activity and species diversity of bats in spruce forests suggests that they may be important to their local populations. Coniferous monocultures can play an important role for local bat populations by acting as migratory corridors and foraging sites.

Role of vernal pools in activity and diversity of bats and birds linked with the emergence of flying insects

Vernal pools are small temporary wetlands occurring in shallow depressions usually filled with precipitation in autumn and winter. They will dry seasonally, which makes them fishless ponds devoid of large aquatic predators. These ephemeral ponds are less studied compared to other freshwater ecosystems, such as lakes, although they are considered biodiversity hotspots. The aim was to study the use of vernal pools by birds and bats and compare this to permanent wetlands. We expected higher bat activity and bird abundance in vernal pools than permanent wetlands, and that is related to the spatial and temporal fluctuations of the emerging flying insects. However, no difference in bird abundance, diversity or community was found between the habitats. Regarding bats, the activity of Myotis spp was generally higher at lakes than vernal pools, while the activity of Eptesicus nilssonii increased during the study period regardless of habitat type. No relationship was found between the emergence of insects and the occurrence of bird and bats. Although, vernal pools were not more attractive habitats compared to lakes, they still form an important, largely neglected, diverse habitat type within the boreal landscape.

Interspecific variation in lower temperature thresholds of an assemblage of wintering bats

Abstract Winter presents environmental and energetic challenges for temperate insectivorous bats as colder temperatures increase metabolic rates while simultaneously reducing resource availability. While bats in northern regions typically hibernate or migrate to circumvent these adverse conditions, there is growing evidence of winter bat activity as weather permits. Bats at lower latitudes may experience shorter, milder winters, increasing opportunities for activity. To better understand the relationship between ambient temperature and winter bat activity, we deployed acoustic detectors in central Louisiana and eastern Texas and examined data at 3 levels of biological organization: overall bat activity, species richness, and species-specific activity. Across 1,576 detector-nights, we recorded 37,435 bat passes. Bats responded positively to warmer temperatures but the temperature threshold for winter activity varied among species, ranging from 7.2 to 15.6 °C. Consequently, observed species richness increased at warmer ambient temperatures. With activity linked to environmental conditions in a species-specific manner, different subsets of the winter bat assemblage may be active from night to night. Additionally, our study adds to a rather limited body of literature of winter bat activity and provides a baseline for future studies as white-nose syndrome and climate change affect North American bat populations.

Bats of the Tunisian Desert: Preliminary Data Using Acoustic Identification and First Record of Taphozous nudiventris in the Country

Increasing aridity usually results in decreasing bat abundance and species richness, and the Saharan desert is an example of such impoverishment. Moreover, the harsh climatic and field conditions in this area restrict the feasibility of surveys. Therefore, the bat fauna of the Tunisian Sahara was unstudied until an expedition was conducted in May 2021. A total of seven species were recorded using passive bat detectors set mainly at water bodies, which concentrate bat activity. Echolocation calls of these species did not depart from published records for the Mediterranean area. Our data failed to identify the two ecomorphotypes of Pipistrellus kuhlii but confirmed the adaptability of this species to local conditions. For the first time in Tunisia, we recorded echolocation calls of Taphozous nudiventris, a species that has been rarely reported in North Africa. The highest species richness was identified at the largest wetlands of Oued Daghsen (Oued Dkouk Nature Reserve) and at Bordj el Khadra (only six and four species, respectively). Most Mediterranean species were recorded in the northern locality, while desert species were more active in the most southern one. The importance of water bodies for bats was confirmed once more. No sign of competition among species was detected, as the Mediterranean and desert-dwelling bat species were active at the same time. Additional surveys should be planned in order to enlarge the list of seven species recorded in only one week.

CXCL13 promotes thermogenesis in mice via recruitment of M2 macrophage and inhibition of inflammation in brown adipose tissue.

Brown adipose tissue (BAT) is mainly responsible for mammalian non-shivering thermogenesis and promotes energy expenditure. Meanwhile, similar to white adipose tissue (WAT), BAT also secretes a variety of adipokines to regulate metabolism through paracrine, autocrine, or endocrine ways. The chemokine C-X-C motif chemokine ligand-13 (CXCL13), a canonical B cell chemokine, functions in inflammation and tumor-related diseases. However, the role of CXCL13 in the adipose tissues is unclear. The expression of CXCL13 in BAT and subcutaneous white adipose tissue (SWAT) of mice under cold stimulation were detected. Local injection of CXCL13 into BAT of normal-diet and high-fat-diet induced obese mice was used to detect thermogenesis and determine cold tolerance. The brown adipocytes were treated with CXCL13 alone or in the presence of macrophages to determine the effects of CXCL13 on thermogenic and inflammation related genes expression in vitro. In this study, we discovered that the expression of CXCL13 in the stromal cells of brown adipose tissue significantly elevated under cold stimulation. Overexpression of CXCL13 in the BAT via local injection could increase energy expenditure and promote thermogenesis in obese mice. Mechanically, CXCL13 could promote thermogenesis via recruiting M2 macrophages in the BAT and, in the meantime, inhibiting pro-inflammatory factor TNFα level. This study revealed the novel role of adipose chemokine CXCL13 in the regulation of BAT activity and thermogenesis.

Providing water sources to insectivorous bats for conservation biological control in arid date plantations

Balance between the high demand for agricultural production and the negative environmental impact of intensive agriculture requires the development of sustainable agricultural approaches. One such approach is conservation biological control (CBC), which aims at enhancing pest suppression by using natural enemies, such as predators and parasites. Insectivorous bats are considered as potential natural enemies for CBC of insect agricultural pests. Bats drink from open water sources and forage above them, hence we hypothesized that supplementation of artificial water pools adjacent to desert date plantations might promote the activity and species richness of insectivorous bats in this habitat, thereby contributing to pest suppression. We predicted that bats will be more attracted to the pools during summer, when other water sources are scarce, than during spring. In addition, we explored the effect of water supplements on the desert bat community structure. Eight pools were installed in a date plantation in the hyper-arid Arava valley, Israel. Bats were acoustically monitored during three experimental stages: 1) before filling the pools with water; 2) while the pools held water and 3) after emptying them. The lesser date moth (Batrachedra amydraula), a major date pest, was monitored using pheromone traps in parallel with the experimental stages. We found that the pools increased bat activity in summer, but not in spring, while species richness was not affected in either season. The local bat community structure was significantly altered while the pools held water, but not due to increased activity of synanthropic Mediterranean species at the expense of local desert species. The number of individuals of the lesser date moth near the pools decreased with the increase in bat activity. Our results support the idea that seasonal water supplementation enhances bat activity in arid farmlands with potential contribution to pest control and the actual contribution to pest suppression should be further quantified. We suggest that the integration of small artificial pools to promote agricultural pest predation by bats may help reduce crop loss and potentially contribute to the conservation of desert bat communities by adding water sources.

An acoustic-based method for locating maternity colonies of rare woodland bats.

Locating colonies of rare bats can be a time consuming process, as it is often difficult to know where to focus survey effort. However, identifying peaks of bat activity via acoustic monitoring may provide insights into whether a colony is locally present, and help screen out sites with low potential. Using a triage approach, we developed a survey methodology for locating colonies of the woodland-specialist barbastelle bat (Barbastella barbastellus). We investigated whether woodland occupancy by a colony could be predicted by acoustic data, and assessed the influence of survey effort (number of acoustic detectors deployed) on detectability. The methodology was then trialled in citizen science surveys of 77 woodlands, with follow-up radio-tracking surveys by specialists being used to confirm presence or absence. Using Receiver Operating Characteristic (ROC) curve analysis, we found that a threshold of four barbastelle passes recorded by at least one detector within one hour of sunset optimised the balance between the true- and false-positive rates. Subsequently, we found that a minimum survey effort of one detector per 6.25 hectares of woodland was needed to ensure a colony would be detected using this threshold, based on a survey sensitivity of 90%. Radio-tracking surveys in a subset of the woodlands, identified as having a high probability of being occupied by a colony based on acoustic monitoring, confirmed the presence of five previously unknown barbastelle maternity colonies. These results demonstrate that a triage system, in which high probability woodland sites are identified based on acoustic survey data, can be used to prioritise sites for future specialist surveys and conservation action.

Factor analysis of the Wind Farm LLC wind park (Donetsk region, Ukraine) impact on bats based on the index of their activity and dynamics of species diversity

In 2019-2020, research on the vocal activity of bats was carried out on the territory of the Wind Farm LLC wind park (800 MW), which is planned to be built near Mariupol (Donetsk region, Ukraine). There were used three methods of material collection: research on the vantage points, on transects and at a stationary point throughout the night. The total number of registered voices is 1554 signals, 695 of which are recorded in 2019 and 859 in 2020. The article shows the dynamics of voice activity by seasons and phases of the life cycle. Based on the activity index of mice, the dynamics of this indicator by months is shown. Forage and migratory behaviour of bats, calculated by determining the index of their activity, shows the average values. An analysis of the territorial distribution shows that bats confined to settlements and open water bodies. The species composition of bats, identified for 1235 signals registered in the territory of the projected wind farm, is stable and represented by widespread at least 10 species belonging to 6 taxonomic ranks. There were revealed some wind turbine generators near which the implementation of minimization measures is required. In total, according to forecasts, there are 10-16 such wind turbine generators within the Wind Farm LLC wind park. Monitoring the state of bats in the project area both during the construction of the wind farm and its operation is mandatory for the development and implementation of measures to minimize the possible negative impact on bats.

TMEM135 links peroxisomes to the regulation of brown fat mitochondrial fission and energy homeostasis

Mitochondrial morphology, which is controlled by mitochondrial fission and fusion, is an important regulator of the thermogenic capacity of brown adipocytes. Adipose-specific peroxisome deficiency impairs thermogenesis by inhibiting cold-induced mitochondrial fission due to decreased mitochondrial membrane content of the peroxisome-derived lipids called plasmalogens. Here, we identify TMEM135 as a critical mediator of the peroxisomal regulation of mitochondrial fission and thermogenesis. Adipose-specific TMEM135 knockout in mice blocks mitochondrial fission, impairs thermogenesis, and increases diet-induced obesity and insulin resistance. Conversely, TMEM135 overexpression promotes mitochondrial division, counteracts obesity and insulin resistance, and rescues thermogenesis in peroxisome-deficient mice. Mechanistically, thermogenic stimuli promote association between peroxisomes and mitochondria and plasmalogen-dependent localization of TMEM135 in mitochondria, where it mediates PKA-dependent phosphorylation and mitochondrial retention of the fission factor Drp1. Together, these results reveal a previously unrecognized inter-organelle communication regulating mitochondrial fission and energy homeostasis and identify TMEM135 as a potential target for therapeutic activation of BAT.

What you hear may not be what you see: Potential of citizen science methods to use bats as riverine forest quality indicators

AbstractMediterranean habitats will be one of the Eurasian ecosystems more strongly affected by Climate Change, especially their riverine systems. Monitoring these ecosystems, which are endemism hotspots and extremely sensitive to changes in rain regimes and extreme weather events like droughts, is of crucial importance. Decades of citizen science projects have proven their utility in highlighting ecological shifts and conservation action priority areas. The Bat Monitoring Programme (www.batmonitoring.org), for instance, has already been used to develop ecological indicators to evaluate the evolution and conservation status of Mediterranean ecosystems. However, using bats as ecological indicators for aquatic ecosystems has resulted in contradicting results, making its application a little controversial. In the present study, we compared two citizen science protocols (visual counting vs. passive acoustic monitoring) used in the Bat Monitoring Programme to test the utility of trawling bats as indicators of Mediterranean riverine habitat quality at both local and landscape scales. By doing so, we aimed to build a specific ecological indicator to determine habitat quality through visual and acoustic counts. Although both protocols presented similar positive significant responses to riverine forest quality, visual counts are suggested as the best sampling approach due to their simplicity and potential within citizen science projects. Moreover, for the first time, we defined threshold values of trawling bat activity to assign different levels of habitat quality to the sampled rivers. We applied them in NE Iberia to exemplify the benefits of using them in a Mediterranean region and discussed the potential, pros and cons of these two citizen science methodologies to establish a pan‐European river biomonitoring programme using trawling bats.

Disentangling mechanisms responsible for wind energy effects on European bats

Mitigating anthropogenic climate change involves deployments of renewable energy worldwide, including wind energy, which can cause significant impacts on flying animals. Bats have highly contrasted responses to wind turbines (WT), either through attraction increasing collision risks, or avoidance leading to habitat losses. However, the underlying mechanisms remain largely unknown despite the expected rapid evolution of WT size and densities. Here, using an extensive acoustic sampling (i.e. 361 sites-nights) up to 1483 m from WT at regional scale, we disentangle the effects of WT size (ground clearance and rotor diameter), configuration (density and distance), and operation (blade rotation speed and wake effect) on hedgerow use by 8 bat species/groups and one vertical community distribution index. Our results reveal that all WT parameters affected bat activity and their vertical distribution. Especially, we show that the relative activity of high-flying species in the community was lower for higher WT density and lower ground clearance. Medium-flying species were sensitive to wind turbine distance, with either attraction or avoidance depending on proximity to the wake area and wind conditions. Specifically, wind turbine distance, wake effect and their interaction each affected the activity of one, three, and three species out of eight, respectively. Blade rotation and rotor diameter affected the activity of four and three species/groups, respectively, and ground clearance affected the activity of five ones. Taken together, WT configuration, operation, and size parameters affected the activity of three, five, and seven out of eight species/groups, respectively. These results call for the consideration of all these factors when assessing the ecological sustainability of future wind farms. The study especially advocates to avoid high WT densities, large rotors, and to site WT as far as possible from optimal habitats such as woody edges and not between them and the source of prevailing winds, in order to limit bats-WT interactions.

Bat boxes in urban bushland are associated with inflated activity of an urban generalist bat, but not an altered community

AbstractBat boxes are often installed as substitute habitats to offset the loss of large, hollow‐bearing trees. However, emerging evidence suggests that they are failing to achieve intended conservation outcomes as they only support generalist species. Despite these concerns, the effect of bat boxes on the dynamics of bat communities remains understudied. We assessed the bat community in reserves where bat boxes had been installed in comparison with reserves where they had not using ultrasonic surveys in 16 small bushland reserves throughout Sydney, Australia. Reserves containing bat boxes and those without had comparable species diversity and composition; however, the activity of the dominant species, Gould's wattled bat (Chalinolobus gouldii), was significantly higher at sites with bat boxes. Species that commonly forage in open vegetation, including C. gouldii, were significantly positively associated with sites that had bat boxes. Occupation of boxes by bats was not recorded in the study due to limited information on their locations, so further research is required to understand the direct effects of boxes and the bats that occupy them on the bat community. If bat boxes continue to be recommended as a biodiversity offset, a greater understanding of the potential impact they have on altered competitive relationships and community dynamics is essential.

Increased bat hunting at polluted streams suggests chemical exposure rather than prey shortage

Streams and their riparian areas are important habitats and foraging sites for bats feeding on emergent aquatic insects. Chemical pollutants entering freshwater streams from agricultural and wastewater sources have been shown to alter aquatic insect emergence, yet little is known about how this impacts insectivorous bats in riparian areas. In this study, we investigate the relationships between the presence of wastewater effluent, in-stream pesticide toxicity, the number of emergent and flying aquatic insects, and the activity and hunting behaviour of bats at 14 streams in southwestern Germany. Stream sites were located in riparian forests, sheltered from direct exposure to pollutants from agricultural and urban areas. We focused on three bat species associated with riparian areas: Myotis daubentonii, M. cf. brandtii, and Pipistrellus pipistrellus. We found that streams with higher pesticide toxicity and more frequent detection of wastewater also tended to be warmer and have higher nutrient and lower oxygen concentrations. We did not observe a reduction of insect emergence, bat activity or hunting rates in association with pesticide toxicity and wastewater detections. Instead, the activity and hunting rates of Myotis spp. were higher at more polluted sites. The observed increase in bat hunting at more polluted streams suggests that instead of reduced prey availability, chemical pollution at the levels measured in the present study could expose bats to pollutants transported from the stream by emergent aquatic insects.