Bat Activity Research Articles

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.

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.

Activity of bats (Chiroptera) in extensive livestock systems in the Colombian Caribbean

Introduction: Extensive cattle ranching in tropical dry forest areas (TDF) has caused the transformation of natural ecosystems and altered the behavior of associated organisms, generating variation in activity patterns. In bats, the activity pattern is affected by the composition and vegetation structure of the ecosystem, and by the climatic season (dry and rainy). Objetive: In this study, the effect of conventional management systems (CS) and silvopastoral (SPS) of extensive livestock management on the bat activity patterns in the Colombian Caribbean was determined. Methods: The activity pattern of bats in TDF fragments associated with CS and SPS was compared within an annual cycle. The daily activity patterns of 11 species with records of more than 10 days in within management systems were determined. Results: Greater bat activity was recorded during the rainy season. We found that although bats show behavioral adaptation to the different management systems, in TDF fragments associated with SPS there is greater bat activity throughout the year, compared to the activity recorded in CS. Species with higher energetic requirements and degree of specialization (Phyllostomus hastatus, P. discolor and Glossophaga soricina) modified their activity patterns between CS and SPS management types. Conclusion: The TDF fragments associated in SSP, due to the vegetation composition and structure, probably favor the constant supply of resources suitable for the bats assemblage stability.

Artificial light at night drives diel activity patterns of synanthropic pipistrelle bats and their prey

The use of artificial light at night (ALAN) has increased drastically worldwide over the last decades. ALAN can have major effects on nocturnal communities, including insects and bats. Insects are attracted to street lights and few bat species take advantage of this by foraging on the attracted insects. ALAN potentially affects the temporal patterns of insect abundance and thereby bat foraging behaviour. In a natural dark environment, these patterns are usually bimodal, with an activity peak in the early evening and the morning. Little is known about how ALAN affects insect presence throughout the night, and whether the light spectrum plays a role. This is important, as these temporal changes may be a key driver of disturbances in bat-insect interactions. Here, we studied how white and red light affect insects' and bats' nightly activity patterns. The activity of insects and bats (Pipistrellus spp.) was recorded throughout the night at seven experimentally illuminated sites in a forest-edge ecosystem. ALAN disrupted activity patterns, with both insects and bats being more active throughout the night. ALAN facilitated all-night foraging in bats especially near white light, but these effects were attenuated near red light. The ability to forage throughout the night may be a key advantage causing synanthropic bats to dominate in illuminated environments, but this could also prove detrimental in the long term. As red light reduced disturbing effects of ALAN on insects and bats diel activity pattern, it opens the possibility of using spectral composition as a mitigation measure.

Wetland restoration enhances habitat for an endangered bat, Eumops floridanus

Restoring lost or degraded wetlands is a major challenge in contemporary conservation. Understanding how wetland restoration and changes in hydrology affect wildlife is increasingly urgent for endangered species conservation. This is especially pertinent for the endangered Florida bonneted bat (Eumops floridanus), whose range is almost entirely contained within one of the world's most iconic wetland systems, the Greater Everglades Ecosystem. We investigated how E. floridanus may respond to future hydrological and vegetation changes associated with current and planned Everglades hydrologic restoration efforts. We conducted acoustic surveys at 194 random points stratified across a restoration gradient (no hydrologic restoration, partial hydrologic restoration, full hydrologic restoration, and reference). Using generalized linear mixed models, we determined the most important predictors explaining variation in bat activity and foraging likelihood. Positive associations between bat activity and several hydrologic variables expected to increase with restoration (hydroperiod, water depth, distance to canals, and extent of freshwater forested wetlands, ecologically intact reference areas, and zones with full hydrological restoration) suggest that foraging habitat for this species will likely benefit from hydrologic restoration both in the near term (immediate increases in hydroperiod and water depth) and in the longer term (as freshwater forested wetlands expand). Our results inform immediate management decisions for this species and suggest the benefits of restoration for wildlife adapted to historically longer hydroperiods and greater water depths, which are anticipated to increase with the gradual return of natural hydrological regimes.

Bat Activity on High Elevation Reforested Coal Mines in the Monongahela National Forest, West Virginia

Bat Activity on High Elevation Reforested Coal Mines in the Monongahela National Forest, West Virginia

More trees and fewer roads: the importance of local and landscape features for insectivorous bats in open urban green spaces

Context Urbanisation poses new challenges for wildlife worldwide, and recent research suggests that urban parks, although highly modified, may act as important refuges. Insectivorous bats can persist in urban landscapes and play an important role in keeping insect populations in balance. Previous research on use of urban landscapes by these bats has often focused on patches of remnant bushland within cities, but their use of highly modified open spaces is not well understood. Aims We aimed to determine the use of open green spaces (e.g. open parks, sports ovals) by insectivorous bats in Melbourne, Australia and to identify landscape factors that influence their presence and activity level. Methods We conducted passive acoustic surveys at 35 sites across greater Melbourne. Once species were identified from the echolocation call data, we modelled species richness, total activity and activity of individual species against landscape and weather variables, using Generalised Linear Mixed Models and Generalised Additive Mixed Models. Key results Across 557 detector nights, we identified at least 11 of the 17 species recorded to occur in Melbourne. Both species richness and activity were greater in areas with more nearby trees and lesser in areas with more roads. There were weaker species-specific relationships between bat activity and both distance to the nearest water source and Normalised Difference Vegetation Index. Species richness and activity levels were lower on nights with a lower temperature at dusk, higher rainfall and stronger wind. Conclusions Our results show that multiple bat species consistently use Melbourne’s open green spaces, highlighting the potential habitat value of these areas, especially those surrounded by high tree densities and fewer roads. Implications Insectivorous bats play important roles within ecosystems and bring benefits to human society. To encourage the diversity and activity of insectivorous bats in urban landscapes, we recommend retaining and increasing indigenous vegetation surrounding open areas in urban parks, as well as more strategic planning of new urban parks that further increases tree density in cities.

Invasion by common reed in peri-urban wetlands does not affect insectivorous bat activity, despite a negative effect on prey abundance

Common reed (Phragmites australis), an exotic invasive plant in North America, alters wetlands and thus affects the abundance, development and behavior of many animal species. We evaluated the effect of common reed invasion on 1) the abundance of nocturnal flying insects, and 2) the activity of one of their predators, insectivorous bats. As bats are highly mobile, they can be affected by parameters at a broad scale. Therefore, we considered 3) the effect of habitats and roads around invaded and non-invaded sites on bat activity. We selected 28 paired sites located in wetlands in southwestern Quebec: 14 control sites and 14 common reed-dominated sites. Nocturnal flying insects were collected in some sites, using light traps. The activity of bats was measured in all sites using acoustic detectors. Habitats and high-traffic roads around the sampled sites were characterized over several spatial scales, using ArcGISPro. Our results showed that the number of nocturnal flying insects was reduced by 53% in common reed-dominated sites, but there was no influence on the overall activity of insectivorous bats. Instead, a larger relative area of aquatic and woodland habitats, within a respective radius of 1 and 2 km in the vicinity of our study sites, favoured the overall activity of bats. Moreover, bat activity decreased with an increase in the length of high-traffic roads within a radius of 200 m around the studied wetland sites. Our results suggest that invasive plants despite reducing insect prey may not represent a major threat to insectivorous bats. They also highlight the importance of protecting forests and aquatic habitats, as well as the need to implement road mitigation measures for the conservation of insectivorous bats.

Toward solving the global green-green dilemma between wind energy production and bat conservation.

Wind energy production is growing rapidly worldwide in an effort to reduce greenhouse gas emissions. However, wind energy production is not environmentally neutral. Negative impacts on volant animals, such as bats, include fatalities at turbines and habitat loss due to land-use change and displacement. Siting turbines away from ecologically sensitive areas and implementing measures to reduce fatalities are critical to protecting bat populations. Restricting turbine operations during periods of high bat activity is the most effective form of mitigation currently available to reduce fatalities. Compensating for habitat loss and offsetting mortality are not often practiced, because meaningful offsets are lacking. Legal frameworks to prevent or mitigate the negative impacts of wind energy on bats are absent in most countries, especially in emerging markets. Therefore, governments and lending institutions are key in reconciling wind energy production with biodiversity goals by requiring sufficient environmental standards for wind energy projects.

The best watering hole in town: Characteristics of ponds used by an endangered bat in an urbanizing boreal landscape

Small waterbodies, or ‘ponds’, have an important role in maintaining biodiversity and ecosystem services, particularly where freshwater sources are limited, such as arid or some urban environments. However, studies that examine the use of ponds by terrestrial wildlife are limited. In the boreal forest, aquatic habitats are important drinking and feeding habitat for endangered little brown bats (Myotis lucifugus), and their relative value likely varies based on their characteristics, such as size, adjacent land cover type, anthropogenic disturbance, and proximity to other water bodies. We examined the characteristics of ponds used by little brown bats along an urban-rural gradient in Yukon, Canada. We used ultrasonic detectors to sample 99 ponds and generalized linear mixed models to determine whether ponds with certain characteristics received more bat activity than others. Ponds were important habitat for little brown bats, as 98% of the ponds we sampled were used. Bats selected ponds based on local rather than landscape level factors, and there was less bat activity at ponds surrounded by additional open water/wetland habitat, which was contrary to our prediction. Ponds that were surrounded by additional open water/wetland habitat may have been too exposed for bats at high latitudes, where nights are short and not completely dark. Isolated ponds that are darker, such as those surrounded by mature forest, may be particularly valuable for little brown bats at high latitudes that exhibit risk-sensitive foraging. We suggest that ponds of comparatively high value for endangered little brown bats be further identified and that these ponds be protected from development, draining, and degradation, and the surrounding mature forest remains intact. More broadly, recognition and conservation of ponds and their surroundings as key habitat for species of bats requires further attention. Understanding the characteristics of ponds selected by threatened bats can help inform conservation priorities and measures that ensure the aquatic habitats they require are maintained in developing landscapes.

Sensitivity of insectivorous bat foraging guilds to urbanization and implications for sustainable development

Substantial urban expansion is expected in global biodiversity hotspots over the next decade, especially in Asia. One such hotspot is Sulawesi, Indonesia, which hosts a diverse array of wild mammals, including bats. While urbanization may threaten some bats, species are not uniformly sensitive to urbanization. Many bat species’ sensitivity to urbanization is associated with their foraging strategies (or foraging guild), but information from Asia, generally, is severely lacking. Here we address this knowledge gap regarding urban sensitivity among insectivorous, echolocating bats within the context of urban informal settlements around the city of Makassar, South Sulawesi. Globally and in Makassar, informal settlements often exist on the fringe of cities, forming an urban-undeveloped land interface. Consequently, they may present opportunities to support conservation for some bats, given a growing focus on nature-based sustainable development solutions to improve the lives of informal settlement residents. We examined how, among informal settlements across Makassar, relative activity of bat sonotypes (in lieu of taxonomic species) from different foraging guilds was related to environmental factors associated with urban expansion. We found bat activity was influenced by processes interacting across multiple spatial scales ranging from the landscape- (e.g., spatial location relative to dense development in the urban core) to local-level (e.g., particular environmental features within 500 m). Broadly, we found some foraging guilds had lower overall relative activity, as well lower activity within the urban core compared to the peri-urban zone, indicating differential sensitivity to urbanization among Makassar’s bats that matches findings elsewhere. However, intensity of both urban and peri-urban informal settlement habitat use by particular bats was driven by a combination of landscape- and local-scale features. At the local scale, tree cover and inland water area frequently influenced sonotype activity in settlements, including urban core habitat use by urban-sensitive bats. Our work demonstrates that, especially if coordinated across broader spatial scales, local nature-based upgrades in informal settlements incorporating diverse green and blue spaces have the potential to enhance suitability of urban zones for both bats and for people.