Insectivorous Bats Research Articles

Roosting ecology of insectivorous bats in a tropical agricultural landscape

Abstract Bats spend more than half of their life in roosts, where key life events transpire. Therefore the availability and selection of roosts are important to bats everywhere, and may limit their ability to exploit every habitat, including agricultural landscapes such as paddy fields, orchards and tea plantations. This study aimed to investigate the day roosts used by insectivorous bat species in tea plantations of Sri Lanka. We surveyed 18 tea plantations where we recorded a total of 44 roosts involving five families and nine species of bats (Hipposideros galeritus, Hipposideros lankadiva, Hipposideros speoris, Rhinolophus beddomei, Rhinolophus rouxii, Megaderma spasma, Pipistrellus ceylonicus, Pipistrellus coromandra and Miniopterus cf. fuliginosus). Most (26) of the recorded roosts were geomorphic, (11) were anthropogenic, and (7) were in vegetation. H. lankadiva and M. cf. fuliginosus are the only species known to roost exclusively in geomorphic roosts; all others were opportunistic. Although protecting bat roosts is crucial for their conservation, it is challenging in view of existing tea management practices. Therefore, natural roosts should be maintained and protected. The introduction of artificial roosts might increase the number of bats able to forage over tea plantations and maximize their consumption of agricultural pests, thereby increasing tea production.

Evaluation of genotoxicity in bat species found on agricultural landscapes of the Cerrado savanna, central Brazil

Habitat loss and fragmentation together represent the most significant threat to the world's biodiversity. In order to guarantee the survival of this diversity, the monitoring of bioindicators can provide important insights into the health of a natural environment. In this context, we used the comet assay and micronucleus test to evaluate the genotoxic susceptibility of 126 bats of eight species captured in soybean and sugarcane plantation areas, together with a control area (conservation unit) in the Cerrado savanna of central Brazil. No significant differences were found between the specimens captured in the sugarcane and control areas in the frequency of micronuclei and DNA damage (comet assay). However, the omnivore Phyllostomus hastatus had a higher frequency of nuclear abnormalities than the frugivore Carollia perspicillata in the sugarcane area. Insectivorous and frugivorous bats presented a higher frequency of genotoxic damage than the nectarivores in the soybean area. In general, DNA damage and micronuclei were significantly more frequent in agricultural environments than in the control area. While agricultural development is an economic necessity in developing countries, the impacts on the natural landscape may result in genotoxic damage to the local fauna, such as bats. Over the medium to long term, then DNA damage may have an increasingly negative impact on the wellbeing of the local species.

Detection of novel paramyxoviruses in Chaerephon bat species in Nigeria and phylogenetics of paramyxoviruses co-evolution with bats in Africa.

Bat paramyxoviruses (PmV) are a diverse group of viruses and include zoonotic viruses such as henipaviruses. Members of this group in other continents have been associated with severe respiratory and neurological infections in animals and humans. Furthermore, despite the richness of diverse bat species that can transmit this virus in African countries like Nigeria, there is very scanty information as to the presence and co-evolution of paramyxoviruses in bats. There is a need for continuous surveillance of zoonotic viruses and their biological reservoirs as this will help in the prevention and management of pathogens' spillovers. This study detected novel paramyxoviruses in Chaerephon nigeriae bat species found in Badagry, Lagos. Phylogenetic analyses of paramyxovirus sequences' co-evolution with frugivorous and insectivorous bats circulating in African countries were also performed using sequences of African origin available in the Database of Bat-Associated Viruses (DBatVir: http://www.mgc.ac.cn/DBatVir/). Oral swabs (n=18) and blood samples (n=32) were collected from C.nigeriae bats in Badagry, Lagos. The L gene of bat paramyxovirus was detected in all oral swabs using PCR techniques. Six of the amplicons were successfully sequenced. Estimated phylogenies placed the sequences in close relationship with those isolated from insectivorous bats. Phylogenetic analyses of previously sequenced isolates in the African region showed the likelihood of different co-evolution mechanisms of paramyxoviruses with frugivorous bats compared with insectivorous bats. This may be due to codon usage bias of the L gene. Spatial distribution of paramyxoviruses in African countries showed limited ongoing surveillance of this virus in the continent, especially in southern and northern countries. Extensive surveillance of paramyxoviruses with possible zoonotic potentials among bat species in the continent is recommended. This will provide further insights into co-evolution as well as prevent possible spillover into the human population.

Effects of adjacent habitat on nocturnal flying insects in vineyards and implications for bat foraging

Bat populations are threatened in many regions of the world, partly due to the loss of foraging and commuting habitats in farmland and declines in insect prey populations caused by agricultural intensification. Given that bats play an important role as bioindicators and in suppressing crop pests, it is crucial to mitigate negative impacts that arise from these threats. In this study we evaluated the richness, quantified at family level, and abundance of bat prey insects in organic vineyards surrounded by three types of adjacent habitat: urban/semi-urban areas, exotic tree plantations, and remnants of native vegetation. The relationship between the abundance of prey and the foraging activity of bats in the vineyards was also examined. Insects were sampled using ultraviolet light traps, located both inside and at the edge of the vineyards. Bat activity was monitored at each site using acoustic recorders. The insect richness was unaffected by the type of adjacent habitat and did not differ between the edge and the interior of the vineyards. In contrast, insect abundance was significantly influenced by the type of adjacent habitat. Vineyards adjacent to native vegetation and exotic tree plantations showed the highest abundances for most insect orders present in the bat diet compared to urban areas. Bat activity was significantly correlated with the abundance of Coleoptera and Lepidoptera, with mixed effects between bat species (negative for Tadarida brasiliensis, positive for Lasiurus varius, Lasiurus villosissimus and Myotis chiloensis). Crop edges adjacent to native vegetation provides important foraging habitat for bats and should therefore be considered in agricultural management. Locating vineyards close to these habitats may promote bat conservation via increased prey insects and may also benefit winegrowers through the ecosystem services provided by insectivorous bats in this crop.

How aerial insectivore bats of different sizes respond to nightly temperature shifts.

Small, volant and nocturnal, bats face strong challenges to avoid heat loss. Among aerial insectivores, body mass varies by two orders of magnitude between the smallest and the largest species. At low temperatures, physiological constraints should be harsher for smaller bats, as they lose more heat through their body surface than larger species. So, temperature variations should lead to distinct behavioural responses by bats of different body masses. Also, because they feed on arthropods, dependent on ambient temperature, aerial insectivores should halt feeding at low temperatures. Using ultrasound detectors and temperature and humidity sensors, we investigated how aerial insectivores of the coldest region in austral Brazil respond to nightly temperature variations and compared those responses between guilds of distinct body masses. We predict that smaller bats reduce their activity faster than larger bats, but that foraging should reduce simultaneously in the two guilds, as they depend on ectothermic prey. Bat activity reduced significantly below 12°C. Larger bats maintained their activity at temperatures where the activity of smaller bats had already halted. However, larger bats foraged mostly during the first half of the night, at higher temperatures than those chosen by smaller bats to forage. We associate these differential responses to the thermal convection process, which may increase prey availability at higher altitudes, where larger molossids are known to forage. Smaller species, mostly edge-space hunters, probably take advantage of less variable prey availability during the night, resulting in a more regular behavioural pattern of navigation and foraging.

Diet and diet-associated heavy metal accumulation in an insectivorous bat (Hipposideros speoris) adapted to dwell in two discrete habitats

Insectivorous bats provide valuable services to agriculture by suppressing crop pests. However, the possibility of toxic metal accumulation in bats with reference to their diet is understudied. We studied the difference in diet and diet-associated heavy metal accumulation in Schneider's leaf-nosed bat (Hipposideros speoris), a species that lives in two discrete habitats (farm and mine) in southern India. Guano samples were collected from respective roost sites during the dry and wet seasons of three consecutive years (2015−2017). Microscopic diet analysis indicated the presence of insects belonging to six orders (Lepidoptera, Coleoptera, Diptera, Hymenoptera, Hemiptera, and Homoptera). Irrespective of habitat, the probability of finding each insect order in the bat diet was high during the wet season. Guano samples were screened for six heavy metal residues (Al, Co, Ni, Cr, Pb, and Hg); these residues varied across the sites and seasons. Aluminum was detected at significantly higher (∼2.5 ×) concentrations in mine bats (dry season: 7.03 ± 0.60 mg/g and wet season: 7.10 ± 1.44 mg/g) compared to farm bats (dry season: 2.52 ± 0.40 mg/g and wet season: 3.28 ± 0.92 mg/g). Guano contained heavy metals in the following order of concentration: Al, Co, Ni, Cr, Pb, and Hg. Irrespective of seasons, all were found at significantly higher concentrations in guano from mine bats than farm bats. This study, therefore, shows a plausible “habitat effect” on heavy metal accumulation in bats. Further, this study sheds light on the potential use of bat guano as a proxy to measure heavy metals that pass through the food web in different environments.

Three-dimensional stratification pattern in an old-growth lowland forest: How does height in canopy and season influence temperate bat activity?

The study of animal–habitat interactions is of primary importance for the formulation of conservation recommendations. Flying, gliding, and climbing animals have the ability to exploit their habitat in a three‐dimensional way, and the vertical canopy structure in forests plays an essential role for habitat suitability. Forest bats as flying mammals may seasonally shift their microhabitat use due to differing energy demands or changing prey availability, but the patterns are not well understood. We investigated three‐dimensional and seasonal habitat use by insectivorous bats in a temperate lowland old‐growth forest, the Belovezhskaya Pushcha in Belarus. We acoustically sampled broadleaved and mixed coniferous plots in the forest interior and in gaps in three heights during two reproductive periods (pregnancy/lactation vs. postlactation). In canopy gaps, vertical stratification in bat activity was less pronounced than in the forest interior. Vertical activity patterns differed among species. The upper canopy levels were important foraging habitats for the open‐space forager guild and for some edge‐space foragers like the Barbastelle bat Barbastella barbastellus and the soprano pipistrelle Pipistrellus pygmaeus. Myotis species had highest activity levels near the ground in forest gaps. Moreover, we found species‐dependent seasonal microhabitat shifts. Generally, all species and species groups considered except Myotis species showed higher activity levels during postlactation. Myotis species tended toward higher activity in the forest interior during postlactation. P. pygmaeus switched from high activity levels in the upper canopy during pregnancy and lactation to high activity levels near the ground during postlactation. We conclude that a full comprehension of forest bat habitat use is only possible when height in canopy and seasonal patterns are considered.

Trait-dependent responses of birds and bats to season and dry forest distance in tropical agroforestry

Agricultural expansion and intensification increasingly threaten birds and bats, especially insectivorous species from the tropics. Cacao agroforests in tropical rainforest areas have been shown to support higher bird and bat biodiversity than other land-use systems, but their suitability for tropical dry forest biodiversity remains unclear. We present the first assessment of bird and bat diversity patterns in cacao agroforests inside tropical dry forest landscapes. We investigated the response of bird and bat species richness and abundance to forest distance and season across 12 smallholder, organic cacao agroforests and adjacent tropical dry forests in the Peruvian lowlands of Piura. We found that insectivorous bird abundance and species richness increased with forest distance in the dry but not in the rainy season, indicating the value of cacao agroforests for these birds when resources are scarce in forests. In the case of bats, we observed more species in agroforests with increasing forest distance independent of season, and the abundance of insectivorous species increased along the gradient. Other dietary groups and forest specialists of both taxa did not vary notably across the forest distance gradient. Our findings point to the relevance of cacao agroforests as alternative habitats for insectivorous birds and bats in tropical dry forest landscapes, especially during the dry season. We suggest that the maintenance of wildlife friendly cacao agroforests, parallel to dry forest conservation and restoration, creates win-win situations for both the conservation of tropical dry forest fauna and the maintenance of related ecosystem services from which cacao smallholders may benefit.

Do the evolutionary interactions between moths and bats promote niche partitioning between bats and birds?

Ecological theory suggests that the coexistence of species is promoted by the partitioning of available resources, as in dietary niche partitioning where predators partition prey. Yet, the mechanisms underlying dietary niche partitioning are not always clear. We used fecal DNA metabarcoding to investigate the diets of seven nocturnal insectivorous bird and bat species. Low diet overlap (2%–22%) supported resource partitioning among all species. Differences in diet corresponded with species identity, prey detection method, and foraging behavior of predators. Insects with ultrasonic hearing capabilities were consumed significantly more often by birds than bats, consistent with an evolved avoidance of echolocating strategies. In turn, bats consumed a greater proportion of noneared insects such as spruce budworms. Overall, our results suggest that evolutionary interactions among bats and moths translate to dietary niche partitioning and coexistence among bats and nocturnal birds.

Characterization of Echolocation Calls from Insectivorous Bats in Puting Bato Cave 5, Burdeos, Polillo Island, Philippines

Acoustic recording is rarely applied in studying Philippine bats, which is reflected by the scarcity of related publications in the country. As a result, the echolocation calls of many local bat species are still unknown, and a reliable bat call library does not exist. Here, we described the echolocation call of some insectivorous bats in Polillo Island and used the call characteristics to define each species. We captured and recorded the echolocation calls of cave-dwelling bats in Puting Bato Cave 5 in October and November 2019. Using BatSound, we measured the spectral and temporal call characteristics and determined the call structure and duty cycle of all recorded individuals. Then, we applied multivariate discriminant function analysis (DFA) to classify the calls into species and identify the call parameter with the highest discriminating power. In total, we recorded 104 individual bats from five species belonging to four families. All species from families Miniopteridae and Vespertilionidae produced steep frequency-modulated (FM) sweeps, while the species belonging to families Hipposideridae and Rhinolophidae emitted calls with constant frequency and FM components. Among the recorded species, Hipposideros coronatus had the highest peak frequency record (> 150 kHz), while Myotis macrotarsus had the lowest (< 40 kHz). Meanwhile, the longest call duration was recorded from Rhinolophus arcuatus (> 40 ms), while Miniopterus paululus produced the shortest call (< 3 ms). The DFA perfectly classified the calls into the correct species and peak frequency was the most important predictor among the call parameters measured. Our results provide strong evidence that insectivorous bats in Puting Bato Cave 5 produce species-specific echolocation calls, and acoustic recording can be a reliable method to enhance research on these cave-dwelling bats

Forest management and conservation of faunal diversity in Italy: a review

We re-examined the knowledge on the relationships between fauna and forest management in Italy. We focused our attention on Vertebrates, including small mammals (Rodents and Soricomorphs), bats, birds, reptiles and amphibians, and on carabid and saproxylic beetles. We found that nearly all groups respond in accordance with Angelstam’s scheme of the traditional forestry cycle, with open habitat specialists followed by generalists and forest specialists when pristine conditions have been attained, though with some differences for some taxa. In all groups, some forest “superspecialists” or old growth indicators could be found, in (sub)Mediterranean forests some carabid beetles could be defined as “dendrophilous,” i.e. associated with the presence of old trees. Poplar plantations are poor substitutes for native forests, as well as exotic conifers. We propose a model for an ideal forest structure that may efficiently preserve the faunal components, at the microscale level this coincides with the structure of an unmanaged old growth forest stand, marked also by a deep and humus-rich soil layer. Some caveats at the landscape scale have dealt with in relation to the size of the designed area, in order to avoid fragmentation effects. A sustainable harvesting scheme has indicated in the “systemic silviculture” proposed by Ciancio and other scientists.

Geographic variation in the skulls of the horseshoe bats, Rhinolophus simulator and R. cf. simulator: Determining the relative contributions of adaptation and drift using geometric morphometrics.

The relative contributions of adaptation and genetic drift to morphological diversification of the skulls of echolocating mammals were investigated using two horseshoe bat species, Rhinolophus simulator and R. cf. simulator, as test cases. We used 3D geometric morphometrics to compare the shapes of skulls of the two lineages collected at various localities in southern Africa. Size and shape variation was predominantly attributed to selective forces; the between‐population variance (B) was not proportional to the within‐population variance (W). Modularity was evident in the crania of R. simulator but absent in the crania of R. cf. simulator and the mandibles of both species. The skulls of the two lineages thus appeared to be under different selection pressures, despite the overlap in their distributions. Difference in the crania of R. cf. simulator was centered largely on the nasal dome region of R. cf. simulator but on the cranium and mandibles of R. simulator. It is likely that the size and shape of the nasal dome, which acts as a frequency‐dependent acoustic horn, is more crucial in R. cf. simulator than in R. simulator because of the higher echolocation frequencies used by R. cf. simulator. A larger nasal dome in R. cf. simulator would allow the emission of higher intensity pulses, resulting in comparable detection distances to that of R. simulator. In contrast, selection pressure is probably more pronounced on the mandibles and cranium of R. simulator to compensate for the loss in bite force because of its elongated rostrum. The predominance of selection probably reflects the stringent association between environment and the optimal functioning of phenotypic characters associated with echolocation and feeding in bats.

Evolution of Complexity. Molecular Aspects of Preassembly.

An extension of neo-Darwinism, termed preassembly, states that genetic material required for many complex traits, such as echolocation, was present long before emergence of the traits. Assembly of genes and gene segments had occurred over protracted time-periods within large libraries of non-coding genes. Epigenetic factors ultimately promoted transfers from noncoding to coding genes, leading to abrupt formation of the trait via de novo genes. This preassembly model explains many observations that to this present day still puzzle biologists: formation of super-complexity in the absence of multiple fossil precursors, as with bat echolocation and flowering plants; major genetic and physical alterations occurring in just a few thousand years, as with housecat evolution; lack of precursors preceding lush periods of species expansion, as in the Cambrian explosion; and evolution of costly traits that exceed their need during evolutionary times, as with human intelligence. What follows in this paper is a mechanism that is not meant to supplant neo-Darwinism; instead, preassembly aims to supplement current ideas when complexity issues leave them struggling.

Sown wildflower fields create temporary foraging habitats for bats in agricultural landscapes

While land-use change threatens insectivorous bats, there is a lack in conservation measures targeting bats in temperate agro-ecosystems. Further, there is no consensus on shared benefits of existing conservation measures either. To unravel the causal factors behind the failure and success of conservation measures, we studied whether sown wildflower fields create sufficient ecological contrast and adequate foraging habitats for insectivorous bats and if potential benefits depend on landscape context.From June to September 2020, we simultaneously monitored insects and bats on paired wildflower and crop fields in landscapes with increasing complexity, here shares of semi-natural habitats such as hedgerows. We compared insect and specifically moth abundance as well as overall bat and foraging activity between wildflower and crop fields and studied effects of prey abundance on bat activity.During summer, insect and moth abundances were two- to fourfold higher on wildflower than crop fields. On wildflower fields, insect abundances increased with wildflower cover, while moth abundances increased with shares of semi-natural habitats. Bat activity on wildflower compared to crop fields was higher during the beginning and lower towards the end of summer. Both bat and foraging activity increased with insect abundance and decreased with patch size of wildflower fields.Wildflower fields seem to be a promising tool to provide adequate foraging habitats for insectivorous bats in agro-ecosystems but sufficient prey availability may be key, particularly during times of high food demand. Moreover, it seems vital to target complex landscapes and foster the retention and reintroduction of hedgerows in agro-ecosystems.

Bats provide a critical ecosystem service by consuming a large diversity of agricultural pest insects

Biodiversity directly influences the delivery of multiple ecosystem services, most notably within agriculture. Projected future global demands for food, fiber and bioenergy will require enhancement of agricultural productivity, but favoring biodiversity-based ecosystem services generally remains underutilized in agricultural practice. In addition, agricultural intensification is a key driver of biodiversity loss. A significant obstacle preventing the adoption of ecologically sensitive practices is a lack of knowledge of the species delivering the services. Insectivorous bats have long been suggested to regulate insect pest populations and may be a critical component of biodiversity-based ecosystem services. Bats may also serve as agents of insect pest surveillance through environmental DNA (eDNA) monitoring approaches. However, the biological and economic importance of bats to agriculture remains under-quantified. Here we catalogued the dietary niche of two North American bats, little brown bat (Myotis lucifugus) and big brown bat (Eptesicus fuscus), through DNA metabarcoding of guano collected from seven roosting sites over a 26-week period. We measured the frequency of occurrence of known pest species in guano samples, compared interspecific differences in diet, and examined seasonal patterns in prey selection. Overall, we detected 653 unique prey species, 160 of which were known agricultural pests or disease vectors. Species diversity of prey species consumed varied by bat species and across the season, with big brown bats accounting for the majority of arthropod diversity detected. However, little brown bats consumed relatively more aquatic insects than big brown bats, suggesting that increased bat species richness in a landscape can amplify their net pest regulation service. Further, we hypothesized that detection probabilities of target insect pests would be higher in guano samples than in conventional survey methods. Multi-survey occupancy modeling revealed significantly lower detectability in bat guano than in conventional monitoring traps, however, highlighting important tradeoffs in selection of survey methods. Overall, the results presented here contribute to a growing evidence base supporting the role bats play in the provisioning of biodiversity-based ecosystem services.

Going out for dinner-The consumption of agriculture pests by bats in urban areas.

Insectivorous bats provide ecosystem services in agricultural and urban landscapes by consuming arthropods that are considered pests. Bat species inhabiting cities are expected to consume insects associated with urban areas, such as mosquitoes, flying termites, moths, and beetles. We captured insectivorous bats in the Federal District of Brazil and used fecal DNA metabarcoding to investigate the arthropod consumed by five bat species living in colonies in city buildings, and ascertained whether their predation was related to ecosystem services. These insectivorous bat species were found to consume 83 morphospecies of arthropods and among these 41 were identified to species, most of which were agricultural pests. We propose that bats may roost in the city areas and forage in the nearby agricultural fields using their ability to fly over long distances. We also calculated the value of the pest suppression ecosystem service by the bats. By a conservative estimation, bats save US$ 94 per hectare of cornfields, accounting for an annual savings of US$ 390.6 million per harvest in Brazil. Our study confirms that, regardless of their roosting location, bats are essential for providing ecosystem services in the cities, with extensive impacts on crops and elsewhere, in addition to significant savings in the use of pesticides.

Trypanosoma cruzi DNA in Desmodus rotundus (common vampire bat) and Histiotus montanus (small big-eared brown bat) from Chile

The protozoan Trypanosoma cruzi, the causative agent of Chagas disease, is transmitted by infected feces or consumption of blood-sucking triatomine insects to several mammalian orders including Chiroptera. In Chile, the distribution of several insectivorous and one hematophagous bat species overlaps with those of triatomine vectors, but the T. cruzi infection status of local chiropterans is unknown. In 2018, we live-captured bats from two protected areas in Chile to collect plagiopatagium tissue, feces and perianal swab samples, in search for T. cruzi-DNA by real time PCR assays using species-specific primers. In Pan de Azúcar island (∼26°S), we examined a roost of Desmodus rotundus (common vampire bat) and sampled tissue from 17 individuals, detecting T. cruzi-DNA in five of them. In Las Chinchillas National Reserve (∼31°S), we examined two roosts of Histiotus montanus (small big-eared brown bat), collecting feces or perianal swab samples from eight individuals, detecting T. cruzi-DNA in four of them. This is the first report of T. cruzi-DNA evidence in bat species from Chile. Both vector-borne and oral transmission are potential infection routes that can explain our results. Further investigation is needed for a better understanding of the role of bats in the T. cruzi transmission cycle.

Deafness in an auditory specialist, the big brown bat (Eptesicus fuscus)

Bats are long-lived animals that show presumed resistance to noise-induced and age-related hearing loss, which has been attributed to their dependence on sound processing for survival. Echolocation and basic auditory functions have been studied extensively in the big brown bat (Eptesicus fuscus), an insectivorous microchiropteran species. We conducted hearing tests and analysis of cochlear sensory cells in a group of big brown bats that exhibited anomalies in behavioral sonar tracking experiments and/or lacked neural responses to acoustic stimulation in subcortical auditory nuclei. We show for the first time the presence of profound deafness and extensive cochlear damage in an echolocating bat species. Auditory brainstem responses were abnormal or absent in these bats, and histological analyses of their cochleae revealed extensive loss of hair cells, supporting cells, and spiral ganglion neurons. The underlying cause of deafness is unknown.

Landscape composition drives the impacts of artificial light at night on insectivorous bats

Among the most prevalent sources of biodiversity declines, Artificial Light At Night (ALAN) is an emerging threat to global biodiversity. Much knowledge has already been gained to reduce impacts. However, the spatial variation of ALAN effects on biodiversity in interaction with landscape composition remains little studied, though it is of the utmost importance to identify lightscapes most in need of action. Several studies have shown that, at local scale, tree cover can intensify positive or negative effects of ALAN on biodiversity, but none have – at landscape scale – studied a wider range of landscape compositions around lit sites. We hypothesized that the magnitude of ALAN effects will depend on landscape composition and species’ tolerance to light. Taking the case of insectivorous bats because of their varying sensitivity to ALAN, we investigated the species-specific activity response to ALAN. Bat activity was recorded along a gradient of light radiance. We ensured a large variability in landscape composition around 253 sampling sites. Among the 13 bat taxa studied, radiance decreased the activity of two groups of the slow-flying gleaner guild (Myotis and Plecotus spp.) and one species of the aerial-hawking guild (Pipistrellus pipistrellus), and increased the activity of two species of the aerial-hawking guild (Pipistrellus kuhlii and Pipistrellus pygmaeus). Among these five effects, the magnitude of four of them was driven by landscape composition. For five other species, ALAN effects were only detectable in particular landscape compositions, making the main effect of radiance undetectable without account for interactions with landscape. Specifically, effects were strongest in non-urban habitats, for both guilds. Results highlight the importance to prioritize ALAN reduction efforts in non-urban habitats, and how important is to account for landscape composition when studying ALAN effects on bats to avoid missing effects.

Selective Logging Shows No Impact on the Dietary Breadth of a Generalist Bat Species: The Fawn Leaf-Nosed Bat (Hipposideros cervinus)

Logging activities degrade forest habitats across large areas of the tropics, but the impacts on trophic interactions that underpin forest ecosystems are poorly understood. DNA metabarcoding provides an invaluable tool to investigate such interactions, allowing analysis at a far greater scale and resolution than has previously been possible. We analysed the diet of the insectivorous fawn leaf-nosed bat Hipposideros cervinus across a forest disturbance gradient in Borneo, using a dataset of ecological interactions from an unprecedented number of bat-derived faecal samples. Bats predominantly consumed insects from the orders Lepidoptera, Diptera, Blattodea, and Coleoptera, and the taxonomic composition of their diet remained relatively consistent across sites regardless of logging disturbance. There was little difference in the richness of prey consumed per-bat in each logging treatment, indicating potential resilience of this species to habitat degradation. In fact, bats consumed a high richness of prey items, and intensive sampling is needed to reliably compare feeding ecology over multiple sites. Multiple bioinformatic parameters were used, to assess how they altered our perception of sampling completeness. While parameter choice altered estimates of completeness, a very high sampling effort was always required to detect the entire prey community.