Bat Activity Research Articles

Tree-volume and forest age increase bat species diversity in boreal urban landscape

ContextGiven the rate at which humankind is changing habitats, it is essential to understand its impact on the surrounding nature and biota. The intensification of human activities and the fragmentation of forested habitats now affect many taxonomic groups, such as bats, which are largely dependent on forests (e.g. roosting sites and feeding areas). Northern Europe is generally considered very forested but intensive land-use changes, caused by urbanization and forestry, contribute to forest fragmentation and loss of biodiversity. Land-use changes are classified as the biggest threats for bats, but especially in the boreal zone, the impact of these environmental changes is not yet known at a sufficient level.ObjectivesWe explored how bats (species occurrences and activity) were influenced by forestry and urbanization, and by landscape variables (tree volume, percentage of deciduous trees, vicinity of water bodies and built areas).MethodsWe used a bioacoustic dataset on bats from Finnish capital area (20 × 20 km, 51 sites) recorded during the summer season (May – September) to evaluate how different habitat classes (old forest, young economical forest, rural area, suburban and urban) and landscape variables influence activity and species richness of bats across this region. We used Hierarchical Modelling of Species Communities (HMSC) approach to characterize the responses of species. We investigated with two different models: one focusing on species occurrences and the second one focusing on relative activity.ResultsOur findings indicate a distinct pattern, with the highest species richness in old forests, followed by a gradual decline with increased land-use intensity. Species-specific responses to habitat classes were evident in both presence and activity. Most of the species showed negative responses to built area, either by their presence or activity. Key landscape variables further underscored species-specific variations in different environmental conditions. Additionally, our study observed temporal dynamics, revealing species-specific variations in occurrences across the bats’ active season.ConclusionOur study sheds light on the complex dynamics of bats in diverse landscapes, emphasizing the crucial role of both habitats and specific environmental factors in conservation. Old natural forests emerge as vital for bats, while land-use changes, especially urbanization, pose challenges highlighting the need for continuous monitoring and strategic conservation actions.

Sown wildflower fields and hedgerows synergistically promote insectivorous bats

AbstractDespite their relevance for anthropogenic impacts on biodiversity, synergistic effects are rarely considered in conservation science or management. However, the implementation of single agri‐environment measures may limit their potential benefits for biodiversity since species often require a multitude of complementary key resources, particularly in homogeneous and structurally poor landscapes. To advance conservation management, we studied whether hedgerows promote benefits of sown wildflower fields for insectivorous bats in temperate agro‐ecosystems. At 12 study sites, we simultaneously monitored bat activity and insect abundances from early to late summer at paired locations, that is, the ecotone of a sown wildflower field bordering a hedgerow and an open boundary of the same wildflower field. Particularly in early and mid‐summer, we found distinct preferences of bats for the ecotone of wildflower field and hedgerow. Yet, independent of the season, neither insects nor specifically moths showed a significant preference for the ecotone. Finally, both bat activity as well as insect abundances shifted towards the ecotone when distance to the nearest forest patch was high. We showed that synergies of hedgerows and wildflower fields promote benefits of the latter for both edge‐ and open‐space foraging bats, particularly in homogeneous and structurally poor agricultural landscapes. Therefore, successful conservation management should take advantage of synergies between complementary conservation measures at the local patch scale and at the same time, account for landscape composition and configuration.

Enhancing insectivorous bat activity through sound manipulation and assessing the contribution of small gaps in windbreaks in the hyper-arid Arava desert

Insectivorous bats are an important group of natural enemies that use echolocation for communication, navigation, and foraging. While foraging, bats often eavesdrop on calls from other foraging individuals and are attracted to them as these indicate prey abundance. In addition, they use hedgerows such as tree lines in agroecosystems for commuting and foraging. In the present study, we employed two approaches to enhance the activity of desert-dwelling bats in fields of melon, pumpkin and onion in the hyper-arid Arava desert, Israel. We predicted that both approaches will enhance the activity of the bats in these agricultural fields. We broadcasted playbacks of echolocation calls of two common desert bats, Hypsugo ariel and Eptesicus bottae over the crop fields as a direct means and used gaps in windbreak lines made of planted trees Tamarix spp. as indirect means. Playback manipulation had differing results between the two species. The activity of H. ariel was initially higher in the control plot, but as broadcasting continued, the manipulated plot exhibited significantly higher activity over onion fields. In contrast, the activity of E. bottae declined over Cucurbit fields in the manipulated plots. These differences may reflect differences between the species in the level of sociality while foraging. The testing of the indirect approach showed that total bat activity and feeding buzzes ratio were significantly higher in small windbreak gaps compared to plots with continues tree line. Our results indicate the potential and the limitations of enhancing bat activity by broadcasting echolocation calls in open crop fields and the importance of landscape features which increase the heterogeneity of the crop fields to attract natural enemies in Conservation Biological Control.

Spatial Metabolomics Reveals the Effects of Dietary Capsaicin Intervention on Interscapular Adipose Tissue Metabolome in Mice.

Capsaicin is a polyphenol with a well-known anti-obesity potential, which could activate brown adipose tissue and promote the browning of white adipose tissue. Indeed, conventional proteomics have been used to investigate the browning effects of capsaicin on adipose tissue. However, the existence of a layer of white adipose tissue above the interscapular brown adipose tissue poses a great challenge to obtain intact interscapular brown adipose tissue without including adjacent white adipose tissue. Therefore, the traditional method normally focuses on changes occurring in the bottom layer of interscapular brown adipose tissue. Spatial metabolomics is an omics method that enables the analysis of metabolite distributions in tissue sections. Therefore, in the current study, spatial metabolomics was utilized to investigate the effects of dietary capsaicin intervention on interscapular brown adipose tissue and adjacent white adipose tissue. The results indicated several noteworthy findings that capsaicin treatment may induce similar metabolite alterations across various regions of brown adipose tissue irrespective of their proximity to WAT, while it also markedly influences the metabolites in the adjacent white adipose tissue. A KEGG pathway analysis further revealed these changes were associated with key characteristics of beige energy metabolism pathways, such as thermogenesis, glycerol phospholipid metabolism, and pentose phosphate pathway. Taken together, this study may supplement useful details to understand the mechanisms of capsaicin enhancing BAT activity and promoting WAT browning.

Agriculture and Water Availability Show Contrasting Effects on Bats in a Mediterranean Island of Outstanding Chiropteran Biogeographical Value

ABSTRACTWith their unique ecosystems and evolutionary dynamics, small islands offer fascinating contexts to explore animal diversity. Island bats are key players in maintaining ecological balance. However, their populations are threatened worldwide, necessitating comprehensive research and conservation strategies. Pantelleria, a small Mediterranean island and a biogeographic crossroad between Europe and Africa, offers an excellent model to exemplify the challenges to bat conservation in such geographic contexts. We tested three hypotheses: (1) bats would show weak preference patterns for landscape composition due to the island's heterogeneous landscapes, (2) farmland (especially vineyards) would strongly affect bat activity, and (3) distance from water sources would highly influence bat richness and activity. We surveyed bats acoustically using Audiomoth recorders covering most of the island's surface. We recorded seven bat species, including endangered Plecotus gaisleri, Myotis punicus and Rhinolophus mehelyi. Bats showed weak preferences for specific landscape composition, but the dominant species (Pipistrellus kuhlii) decreased its activity for increasing portions of vineyards within the landscape. Moreover, distance to water critically influenced bat richness and activity. Agricultural expansion, pesticide use and human activities pose significant threats to bats on Pantelleria. We advocate for sustainable farming practices and careful water resource management to safeguard bat habitats and mitigate these threats. Conservation should target vineyards, a key economic resource to produce world‐renowned wine ‘Passito di Pantelleria’ by reducing pesticide use and adopting organic management. Water might be supplemented in critical dry habitats. We urge the preservation of bat diversity to support ecosystem health and resilience on small islands like Pantelleria.

Cold-inducible GOT1 activates the malate-aspartate shuttle in brown adipose tissue to support fuel preference for fatty acids.

Got1 is markedly induced by cold in BAT via a β-adrenergic receptor-PKA-PGC-1α axis The increase in cytosolic GOT1 activates the malate-aspartate shuttle (MAS)MAS activation promotes fatty acid oxidation while reducing glucose oxidation Loss of MAS activity in BAT by Got1 deletion shifts the fuel preference to glucose.

High-iron diet damages brown adipose tissue mitochondria and exacerbates metabolic hazards of a high-fat diet

Metabolic diseases may be prevented by reducing carbohydrate intake and replacing plant-based diets with animal-based ones low in carbohydrates but high in protein, fat, and iron. While the effects of sugars on metabolic diseases are well-known, the role of iron remains unclear. This study aimed to explore the effects of a high-fat high-iron animal diet on body metabolism in mice. Micro-PET imaging was used to assess 18-F-labelled glucose uptake in BAT, and the morphology, respiratory function, and oxidative stress of BAT mitochondria were examined. The underlying mechanisms were elucidated by analyzing the expression of UCP-1, PGC-1α and PPARα. The high-iron high-fat diet increased appetite, impaired glucose tolerance, and reduced insulin sensitivity. Additionally, the high-iron diet promoted gluconeogenesis only in the absence of high-fat levels. Both high-iron and high-fat diets suppressed BAT activity, increased mitochondrial oxidative stress, decreased mitochondrial respiratory function, and lowered thermogenic gene expression. Weight loss strategies focusing solely on reducing carbohydrates and increasing animal foods, like ketogenic diets, may have long-term detrimental effects on metabolic health. Prioritizing dietary diversity and monitoring overall caloric intake is advisable for optimal outcomes.

Seasonal variation of bat activity in an endangered temperate forest in the Chilean biodiversity hotspot

Seasonal variation of bat activity in an endangered temperate forest in the Chilean biodiversity hotspot

Non-invasive monitoring of adrenocortical activity in the Gould’s wattled bat (Chalinolobus gouldii)

Although bats are the second most species-rich mammalian order, very little is known about their endocrine physiology. Glucocorticoids (GCs) are commonly associated with the stress response, but also modulate vital physiological functions which help animals adapt to their environment. Understanding normal patterns of adrenocortical activity can provide valuable insights into a species’ fitness. Non-invasive hormone monitoring via faecal samples provides an integrated measure of adrenocortical activity while minimising stress on the animal but must be properly validated to ensure reliable results. The goal of this study was to validate an enzyme immunoassay for monitoring faecal glucocorticoid metabolites (FGMs) in a common Australian insectivorous bat species, the Gould’s wattled bat (Chalinolobus gouldii). We compared the performance of five assays for monitoring changes in FGMs following capture and transfer of C.gouldii from the wild to captivity. Four of the five assays detected a significant increase in FGMs following capture, but the magnitude of the increase and consistency across individuals differed considerably. We selected the UVM-69a assay as the best performing assay to then describe normative patterns of adrenocortical activity in the species. Males had higher FGM levels than females, and juveniles had higher FGM levels than adults. Individuals with poorer body condition had higher FGM levels. We also demonstrate seasonal patterns of FGMs with higher levels in March and April corresponding with reproductive up-regulation and lower levels in May and November. Our study is the first of its kind to examine adrenocortical activity in an Australian insectivorous bat and provides a valuable tool for studying this species. Understanding adrenal function in common species such as C.gouldii can shed light on the physiological mechanisms facilitating survival and success in changing environments.

The interplay of temperature and circadian periodicity in winter activity of non-cavernous hibernator, Nyctalusnoctula

Winter activity of hibernating mammals is likely to be influenced by climate change. Our study focuses on Nyctalus noctula, a non-cavernous hibernator using artificial roosts in a recently colonized winter region. Using continuous acoustic monitoring and temperature measurements inside and outside the roosts, we found that bats exhibit a circadian cycle (active at night, resting during the day) even during hibernation season. Activity duration and intensity changed in response to ambient temperature, photoperiod, and hibernation progression. Warm ambient temperatures led to increased nighttime activity, extending the duration of the active phase. As photoperiod increased, the rest phase lengthened, while the overall magnitude of activity decreased from the beginning to the end of the hibernation period. Below 0 °C vocal activity was nearly zero indicating a minimal probability of bat activity during both day and night. The species recent success in extending its hibernation range northward may be attributed to its flexible adjustment to prevailing environmental conditions. Nevertheless, it remains uncertain whether engaging in daily activity at temperatures above 0 °C confers any advantages at northern latitudes to prevent premature energy depletion. The persistence of circadian activity during winter could be a relic behavior, adapted from historical patterns of wintering in insect-rich and warm southern latitudes.

HDAC5 controls a hypothalamic STAT5b-TH axis, the sympathetic activation of ATP-consuming futile cycles and adult-onset obesity in male mice

With age, metabolic perturbations accumulate to elevate our obesity burden. While age-onset obesity is mostly driven by a sedentary lifestyle and high calorie intake, genetic and epigenetic factors also play a role. Among these, members of the large histone deacetylase (HDAC) family are of particular importance as key metabolic determinants for healthy ageing, or metabolic dysfunction. Here, we aimed to interrogate the role of class 2 family member HDAC5 in controlling systemic metabolism and age-related obesity under non-obesogenic conditions. Starting at 6 months of age, we observed adult-onset obesity in chow-fed male global HDAC5-KO mice, that was accompanied by marked reductions in adrenergic-stimulated ATP-consuming futile cycles, including BAT activity and UCP1 levels, WAT-lipolysis, skeletal muscle, WAT and liver futile creatine and calcium cycles, and ultimately energy expenditure. Female mice did not differ between genotypes. The lower peripheral sympathetic nervous system (SNS) activity in mature male KO mice was linked to higher dopaminergic neuronal activity within the dorsomedial arcuate nucleus (dmARC) and elevated hypothalamic dopamine levels. Mechanistically, we reveal that hypothalamic HDAC5 acts as co-repressor of STAT5b over the control of Tyrosine hydroxylase (TH) gene transactivation, which ultimately orchestrates the activity of dmARH dopaminergic neurons and energy metabolism in male mice under non-obesogenic conditions.

Re-establishing historic ecosystem links through targeted species reintroduction: Beaver-mediated wetlands support increased bat activity

Despite the global significance of wetlands, conservation strategies often fall short in preserving these ecosystems due to failures in incorporating processes that sustain the ecosystem functioning, hydrological dynamics, ecological processes, and biodiversity of wetlands. Nature-based solutions, such as the reintroduction of beavers, have emerged as effective tools for promoting wetland restoration. Whilst the impact of beavers on wetland restoration is well known, their broader influence on ecosystem health, particularly in modifying habitats for other species, remains inadequately understood. Here we assess the impact that habitat modification through the reintroduction of beavers has on bat populations. There were significantly greater activity levels within beaver-modified wetland habitats for multiple bat species, including higher activity levels of 393 % for Barbastella barbastellus and 313 % for Plecotus spp.. Additionally, we observed positive effects on bat populations in the woodland habitat surrounding beaver-modified wetland for certain taxa. In the face of escalating challenges posed by climate change and habitat loss, addressing biodiversity loss necessitates a shift toward ecosystem-centric mitigation measures. Our study demonstrates that the reintroduction of keystone species like beavers can re-establish historical facilitative links between aquatic and terrestrial food webs, highlighting the importance of such interventions in fostering the resilience and sustainability of entire ecosystems.

Traits and trails: Guild-specific effects of forest paths on bat activity

Human activities can substantially alter forest structure, consequently affecting forest animal communities. An important effect on bat behavior is given by canopy discontinuities like clearings or trails: while the former act as foraging sites, the latter are known to be used by bats to move inside the forest. For this reason, we can expect trails to have a strong influence on bat activity, with differences determined by the species' flying abilities. Here we assess the impact of trails on a local bat community by quantifying the effect of trails’ characteristics on the activity of bat species in relation to their wing morphology. We collected paired acoustic data and environmental variables along trails and in internal areas of a forest in central Italy. We modelled the activity levels of three bat guilds differing in wing morphology and identified the species mostly responsible for the observed compositional dissimilarity in between trails and internal zones by adopting a multivariate approach. Trail width and tree’s diameter were the main drivers of the observed differences between bat activity along trails and internal areas, but their effect differed among bat guilds. Edge and open-space foragers increased their activity along wider trails, while closed-space foragers showed an opposite trend; the latter also avoid trails in favor of internal areas especially when trees are larger. Four species yielded a significant contribution to the dissimilarity in activity levels between trails and internal areas, and namely Pipistrellus pipistrellus, Nyctalus noctula, Miniopterus schreibersii and Barbastella barbastellus. Our results show a clear effect of forest trails on bat activity, highlighting differences across functional groups in relation to trail characteristics. Furthermore, within guilds, not all species respond with the same intensity, suggesting differences in how different species are attracted to linear features and forest gaps. Overall, our results depict a complex interaction between forest trails and bat activity, suggesting that structural changes in forests can trigger diverse responses in bats. Future research on the topic may focus on assessing how such effects can affect bat communities at the landscape scale and longer time-scales.

Effects of Habitat Management for Small Game Species on Bat Activity in Three French Mediterranean Scrublands

Effects of Habitat Management for Small Game Species on Bat Activity in Three French Mediterranean Scrublands

Anthropogenic Effects on Bat Activity and Diversity along the Eerste River, South Africa

Anthropogenic Effects on Bat Activity and Diversity along the Eerste River, South Africa

The Influence of Urbanization on Bat Species Composition and Activity in Baton Rouge, Louisiana

The Influence of Urbanization on Bat Species Composition and Activity in Baton Rouge, Louisiana

Abstract Tu036: Adipose tissue plasticity in response to early pathological stress on the heart and mediation by adipose thermogenic activation

Background: Cardiovascular diseases (CVD) are the leading cause of death globally, accounting for approximately 17.9 million mortalities per year. Previous studies have shown that there is an early response of white and brown adipose tissue (WAT and BAT, respectively) to pathological stress on the heart prior to cardiac dysfunction. Interestingly, human subjects with detectable BAT activity (a thermogenic tissue) exhibit a reduced risk of Congestive Heart Failure, but the mechanism for this is unclear. We hypothesized that increasing the thermogenic acitivity of adipose tissue would be beneficial during the initial cardiac hypertrophic signaling prior to the development of compensatory hypertrophy. Methods: We studied both WAT and BAT in male and female C57BL/6J mice subjected to cardiac pressure overload via transaortic constriction (TAC). 24 hours post-surgery, mice were subjected to room temperature (RT) 22° C or mild cold 16°C to stimulate BAT activation for 48 hours after which tissues were collected. The study groups included: SHAM RT, TAC RT, SHAM COLD, TAC COLD. We used uncoupling protein 1 knockout (UCP1-KO) mice, with impaired thermogenic activity as a negative control. Results: At 72 hours post tac surgery, expression of thermogenic and metabolic genes remained unchanged in BAT and WAT of both sexes. However, mild cold exposure resulted in an increase in UCP1 expression in BAT of male, but not female mice while other metabolic and thermogenic gene markers’ expression was increased in a sex-specific manner. Adaptations to scWAT were more moderate than BAT, with an increase in Ucp1 after cold exposure in both sexes. Moreover, 48 hours of cold exposure attenuated expression of gene markers for hypertrophic signaling in the heart during TAC. Importantly, these adaptations were absent in UCP1-KO mice, signifying that intact thermogenic activity in adipose tissue was required for the attenuated expression of hypertrophic markers in the heart. Interestingly, cardiac fibrosis markers were downregulated with TAC-Cold in male mice only, suggesting a stronger response compared to female mice. Conclusions: Our findings demonstrate that pathological stress on the heart during TAC does not impact adipose tisse thermogenesis. Additionally, activating thermogenic gene expression of adipose tissue via cold exposure mediates the early induction of hypertrophic signaling in the heart within 72 hours of TAC. Notably, adipose tissue plasticity is sex-specific.

Microclimatic drivers of winter bat activity in coast redwood forests.

Bats are among the least well-known mammals, particularly in terms of their behavior and activity patterns during the winter. Here, we use passive acoustic monitoring to overcome some of the challenges inherent in surveying cryptic forest bats during the wet season to quantify overwintering behavior for 11 species in California coast redwood forests under varying microclimates. Because different species are active at different forest heights, we also examined the effect of acoustic detector placement (treetop or ground level). Generalized linear mixed models were used to relate acoustic detection probability for 8 species to daytime and nighttime temperature, relative humidity, water vapor pressure, and detector placement. The results indicate that daytime maximum temperature best explained variation in nightly probability of detection, and temperature threshold at which bats were predicted to be detected varied considerably across species. By using more precise species detection methods, we were able to resolve significant differences in activity patterns between Myotis yumanensis and M. californicus, 2 species with similar acoustic signatures that are often lumped together. Myotis californicus was predicted to have a 50% probability of detection at maximum daytime temperature as low as 12.5 °C, whereas M. yumanensis was not predicted to have 50% detection probability until maximum daytime temperature was at least 22 °C, suggesting that M. californicus spends less time in torpor. Also, monitoring at the top of the canopy revealed 4 migratory species to be present in the ecosystem on significantly more monitoring nights than could be observed using conventional ground-based monitoring methods. Improving winter bat survey methods provides evidence that diverse bat species are more active in redwood forests during the winter than previously documented. This finding suggests that coastal forests could provide important winter bat habitat for both resident and migratory species.

Forest characteristics predict Tri-colored Bat (Perimyotis subflavus) activity within novel Colorado habitats

Forest characteristics predict Tri-colored Bat (<i>Perimyotis subflavus</i>) activity within novel Colorado habitats

Disturbance of hibernating bats due to researchers entering caves to conduct hibernacula surveys

Estimating population changes of bats is important for their conservation. Population estimates of hibernating bats are often calculated by researchers entering hibernacula to count bats; however, the disturbance caused by these surveys can cause bats to arouse unnaturally, fly, and lose body mass. We conducted 17 hibernacula surveys in 9 caves from 2013 to 2018 and used acoustic detectors to document cave-exiting bats the night following our surveys. We predicted that cave-exiting flights (i.e., bats flying out and then back into caves) of Townsend’s big-eared bats (Corynorhinus townsendii) and western small-footed myotis (Myotis ciliolabrum) would be higher the night following hibernacula surveys than on nights following no surveys. Those two species, however, did not fly out of caves more than predicted the night following 82% of surveys. Nonetheless, the activity of bats flying out of caves following surveys was related to a disturbance factor (i.e., number of researchers × total time in a cave). We produced a parsimonious model for predicting the probability of Townsend’s big-eared bats flying out of caves as a function of disturbance factor and ambient temperature. That model can be used to help biologists plan for the number of researchers, and the length of time those individuals are in a cave to minimize disturbing bats.