Bat Foraging Activity Research Articles

Batting around a new idea: attracting insect buffets for endangered bats

During the autumn months, many bat species face challenges to find sufficient food and generate the large fat stores they require to survive winter. However, North American bats face an additional challenge: a fungal disease called white-nose syndrome. The disease causes bats to arouse too frequently during hibernation, eventually starving to death before spring. Twelve bat species are currently affected, and some are listed as Endangered in either the USA or Canada. Winifred Frick, from Bat Conservation International and the University of California, Santa Cruz, USA, with a team of collaborators from various US and Canadian institutions, set out to test a new conservation approach that could protect bats by increasing the number of flying insects in an area, allowing the animals to gorge before and after hibernation.To test their approach, the team chose caves in the Upper Peninsula of Michigan, USA, which were known to have ∼100 remaining hibernating little brown bats (Myotis lucifugus) after declines from white-nose syndrome. They then monitored five caves in the autumn of 2019 (1 September–4 October), when the bats were fattening for hibernation, and four caves in the spring of 2021 (19 April–25 May), when bats that survived white-nose syndrome were emerging from hibernation. To attract flying insects, Frick and colleagues placed a single UV light 250 m from each cave entrance, 3 m above the ground. In the autumn, the team alternated nights when the UV lights were on, to assess changes in the number of insects they attracted. However, in the spring, to determine whether the bats could learn to respond to changes in the numbers of insects available to dine on, some of the caves were provided with a UV light on each night, while others had no UV lights on.The team also measured insect abundance every night during the autumn but only once a week during the spring, using a funnel and bucket to trap insects that were then brought back to the lab to be weighted and identified. To monitor bat foraging activity at the caves, the researchers used bat detectors placed at the sites to record the bats’ ultrasonic calls while flying from sunset to sunrise each night during the autumn and spring. Back in the lab, the recordings were reviewed to identify and count the number of ‘feeding buzzes’ – the echolocation calls that bats make when successfully catching insects – to determine the bats’ foraging success rates.The researchers found that when the UV lights were on during the autumn fattening period, the bats successfully captured and ate three times more insects than on nights when the UV lights were off. Additionally, the team collected a far greater mass of insects (16.7 times more) on the UV illuminated nights. Additionally, in the spring, the hunting bats were 8.5 times more successful in capturing prey, and the mass of insects collected by the team was 26.1 times greater at the locations where the UV lights were on than at the locations where the UV lights were off. These results show that UV lights in the autumn and spring increase the insect abundance for bats to eat, and that bats learn to forage more when there is increased food availability.Overall, Frick and colleagues have successively shown a novel approach for artificially attracting greater numbers of insects for bats to feast on during the critical spring and autumn periods. The results from the study could aid in the recovery of bat populations from white-nose syndrome and inspire wider conservation approaches for critically endangered hibernating bats in North America.

Comparison of the Foraging Activity of Bats in Coniferous, Mixed, and Deciduous Managed Forests

The aim of this study was to compare the foraging activity of bats in coniferous, deciduous, and mixed forests and to test whether this activity was subject to seasonal variation. Sample points were selected in stands of similar spatial structure in coniferous (Pinus sylvestris L.), in mixed (Pinus sylvestris and Quercus petraea (Matt.) Liebl.), and in deciduous (Quercus petraea) managed forests in western Poland. Bat calls were recorded using automated ultrasound recording devices (Batcorder 3.0, ecoObs, Nürnberg, Germany) during five consecutive nights from May to September in each of the six stands. A total of 4250 bat passes were recorded. Overall, 63.1% of bat passes were identified to species, 31.6% were identified to genus or sonotype group, and 5.3% remained unidentified. In total, eight species of bats and seven sonotype groups were recorded. The dominant species in all types of forests were Pipistrellus pygmaeus (44.5% of recorded bat passes), followed by Nyctalus noctula (10.3%) and Pipistrellus nathusii (5.7%). There were no significant differences in the total activity of bats between the three types of forests; however, high seasonal fluctuations in bat foraging activity were found. This study demonstrates that when coniferous, deciduous, and mixed stands with similar spatial structure are compared, forest type does not affect the foraging activity of bats.

Bats increased foraging activity at experimental prey patches near hibernacula

Abstract Emerging infectious diseases in wildlife can threaten vulnerable host populations. Actions targeting habitat improvements to aid population resilience and recovery may be beneficial long‐term strategies, yet testing the efficacy of such strategies before major conservation investments are made can be challenging. The disease white‐nose syndrome (WNS) has caused severe declines in several species of North American hibernating bats. We tested a novel conservation approach targeted at improving foraging conditions near bat hibernacula by experimentally manipulating insect density in the pre‐hibernation fattening period and spring emergence recovery period. We measured foraging (feeding buzzes) and echolocation activity of little brown bats Myotis lucifugus at ultraviolet (UV) light lures to determine behavioural response to augmented foraging conditions and characterized insect availability at UV light lures. In the fall, bat foraging activity was three times greater (95% CI: 1.5–5.8; p = 0.002) when UV lights were on, but there was no statistical support for differences in echolocation activity response when our experimental design alternated between nights with lights on and off. In the spring, we allowed UV light lures to run consistently each night and compared with a control location in similar habitat. Bat foraging activity was 8.5 times greater (95% CI: 4.5–16.0; p < 0.0001) and echolocation activity was 4.4 times higher (95% CI: 3.0–6.5; p < 0.0001) at UV light lures in the spring experiment. In both the fall and spring, UV light lures resulted in concentrated insect availability, attracting primarily moths (Order: Lepidoptera). In both seasons, nightly temperature had a strong influence on bat foraging, echolocation and insect activity. We show that a bat species threatened by WNS used enhanced foraging habitats near hibernacula during the critical pre‐ and post‐hibernation phases of their annual cycle. While light lures are unlikely to be a long‐term management strategy, our experiment provides initial evidence that bats behaviourally respond with increased foraging activity in areas with augmented insect prey availability. Our experimental results support developing management strategies focused on habitat protection, including restoration and enhancement of foraging habitats, in the immediate vicinity of bat hibernacula.

Diverse agricultural landscapes increase bat activity and diversity: Implications for biological pest control

Diverse landscapes consisting of mixed crops are expected to support higher biological control, while also contributing to maintain farmland biodiversity. Although bats are known as predators of many farming pests, few studies to date have investigated how their foraging activity may enhance natural pest control.Here, we tested the hypothesis that crop mosaics would provide a temporal continuity in prey availability for bats, ultimately resulting in higher biological control. We sampled bat activity and diversity, and the abundance and damage of three major pests of vineyards, maize, and pine plantations, in both simple and diverse landscapes mixing the three production types. Bat species richness and total activity were higher in vineyards and pine plantations located within diverse landscapes. Bat foraging activity also peaked within diverse landscapes. In vineyards, moth abundance decreased with bat species richness. In pine plantations, pest damage decreased with bat foraging activity. In maize fields, pest abundance and damage increased with bat richness and activity longer-term investigations would be necessary to assess their actual effectiveness. Our study advocates for promoting a diversity of coexisting crops within agricultural landscapes to enhance bat activity and diversity, which in turn would sustain higher biological control and bolster biodiversity conservation in farmland.

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

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

Contrasting effects of street light shapes and LED color temperatures on nocturnal insects and bats

Street lights are important light sources that contribute to artificial light at night (ALAN). To date, ecological impacts of individual LED properties (color temperature, dimmability) have been studied, while interactions between light properties or aspects of luminaire design have not been addressed. However, the design of luminaires can influence ALAN impacts as the shape determines the spatial distribution of light and its visibility in the environment. This may cause amplifying or mitigating effects. We assessed the relative individual and interacting effects of two LED luminaire designs and three LED color temperatures (1750 K, 3000 K, 4000 K) on nocturnal insect abundance, bat foraging and feeding activity. We considered a standard LED luminaire shape with focused light emission and a luminaire shape with a diffusor to scatter the light spatially, leading to increased visibility of the light in the environment. During 104 nights, we trapped 51263 nocturnal insects of which 97% were caught at lights and 3% at dark sites. For bats, up to 44.8% fewer acoustic signals were recorded at dark sites. We caught 31% insects at LEDs with1750 K, 34% and 35% at 3000 K and 4000 K, respectively. Thus, color temperatures of 1750 K proved less detrimental than 3000/4000 K. Effects of luminaire shape led to an increase (16%) of trapped insects for luminaires with diffusors compared to the standard shape. In addition, luminaires with diffusors amplified the effects of LED color (+12% insects at 1750 K/3000 K; +25.6% at 4000 K). In contrast, bat foraging activity was independent of the light treatments while bat feeding activity was increased by 21.5% at standard luminaire shapes. Likely, intense straylight at diffused lights negatively affects the target-focused echolocation by deterring the bats. We concluded that ecological impacts of luminaire shape are an important, yet underestimated variable in light-pollution impact research.

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.

Contribution of emergent aquatic insects to the trophic variation of tropical birds and bats

Food webs are spatially connected by cross-ecosystem fluxes of resources, especially in aquatic-terrestrial boundaries. Generalist consumers are often supported by allochthonous resources, which can influence their density, biomass, and distribution. In this study, we investigated the influence of allochthonous aquatic resources on the foraging activity of bats (by ultrasound emissions) and richness of birds (by birdsong records). We also used stable isotope analysis of δ13C and δ15N to determine their diet and trophic space using bayesian Standard Ellipse Area (SEA). We evaluated these responses in near-site (0-1 m from stream margin) and far-site (200 m from stream margin) from six streams in the Atlantic and the Amazon Forest. Foraging activity of bats and richness of Amazonian birds were higher in near-sites compared to far-sites, while Atlantic bird richness was higher in far-sites. We found that emergent aquatic insects and spiders contributed to 46–45% and 49–36% of the diet of insectivorous bats and birds, respectively, regardless of the distance from streams. In Atlantic Forest, SEA of both birds and bats were not compared between plots because of the low sample size. In Amazon Forest, the far-site trophic space of birds showed a higher δ15N position in the bi-plot. These findings suggest that allochthonous resources are important for areas near and far from streams. Our study underscores the importance of preserving both near and adjacent far habitats in the maintenance of trophic interaction involving flying vertebrates and highlights the interdependence of those areas via allochthonous subsidies.

Responses of bat-prey to prescribed burns and mechanical thinning

Insects are an important aspect of forest and woodland ecosystems due to their role as prey for vertebrate species. Our research investigated the relationship between insects and forest management practices in the Ozark National Forest in Arkansas. We looked at the differences in biomass, abundance, and diversity of insects in 30 treatment stands with varying burn frequencies. Twelve of these stands were burned and mechanically thinned, 12 were only burned, and 6 were untreated. The burn frequencies of these stands range from being burned 0–4 times from 2007 to 2018. We deployed blacklight traps in each of the stands every month from mid-March to mid-November in 2019 to assess nocturnal bat prey. Over 30,070 insects were collected, with Lepidoptera being the most abundant order. Insects were dried, weighed, and identified for diversity metrics. We used multi-model selection and AICc to find the top models from a series of linear mixed effects models to determine the best forest management strategies for bat prey. Total nocturnal, aerial insect biomass, Lepidoptera biomass, and Macroheterocera abundance was lower in thinned stands. However, it is unclear if it is the removal of Lepidoptera tree hosts or changes to bat foraging activity that drove this relationship. Stands burned at high frequencies had a higher abundance of Coleoptera. The intermediate disturbance hypothesis was not supported with regards to Lepidoptera diversity and burn frequency. Burning at high frequencies (4 times per 12 years) and not thinning may be the best strategy for maximizing nocturnal Coleoptera and Lepidoptera, respectively.

Free-ranging livestock and a diverse landscape structure increase bat foraging in mountainous landscapes

Traditional farming, where livestock is seasonally managed as free ranging and the use of drugs is reduced or absent, may prove beneficial to biodiversity by fostering the occurrence of spatial heterogeneity, and increasing the availability of trophic resources to wildlife. Previous work indicates that the presence of cattle in lowlands leads to an increase in bat foraging activity, yet no study has addressed this topic in mountainous regions, where free-ranging livestock is still common. Here we explore the relationships between landscape structure, farming and bat activity in a mountainous agricultural area, hypothesizing that bat activity will increase in response to the presence of livestock and landscape structure and heterogeneity. We found that traditional cattle farming may have a role in influencing bat activity in mountainous agroecosystems, yet its effects are evident for a limited number of species. Three pipistrelle species favoured foraging in areas subjected to cattle farming by hunting more often over cattle or fresh dung than at control sites. Free-ranging cattle thus provide profitable foraging opportunities for bats in mountainous landscapes, which remarks the importance of traditional farming activities in sustaining biodiversity. Cattle might also benefit from bat foraging activity if this leads to suppression of blood-sucking pests.

Tidying up the cluttered understorey: Foraging strategy mediates bat activity responses to invasive rhododendron

Biological invasions pose a significant threat to biodiversity, yet the severity and direction of impacts differs between taxa. The non-native evergreen shrub Rhododendron ponticum has colonized large areas of woodland understorey in the UK and is currently undergoing widespread clearance due to its negative impacts on native flora and as a potential host reservoir for harmful pathogens. Presence of rhododendron significantly increases the amount of structural clutter in the understorey and, hence, modifies microhabitat structure, which might have an impact on bat foraging activity. Here, for the first time, we investigated the effects of rhododendron on activity of British bat species by performing autonomous acoustic surveys at twelve sites in Richmond Park, London, where rhododendron was either present, absent or recently removed. The effects of other microhabitat characteristics likely to influence bat activity (e.g. tree diversity, canopy cover, distance to water and the presence/absence of deer) were also considered. We predicted that the increased understorey clutter present in areas invaded by rhododendron would reduce the activity of larger, less agile bats Nyctalus noctula, Eptesicus serotinus and Nyctalus leisleri (NSL), whereas the activity of bat species able to forage within, or at the edges of, clutter (e.g. Myotis spp. and Pipistrellus spp.) would not be negatively affected. While our results indicated a significant reduction in the activity of larger, open space foragers (NSL) in rhododendron-invaded areas, deer presence had a stronger negative effect than woody understory density and canopy cover on these bat species. Activity of other bats recorded was not negatively impacted by the presence of rhododendron. However, sites where rhododendron had been removed demonstrated higher bat activity levels than sites where rhododendron was present and absent with the exception of Pipistrellus pygmaeus, which displayed higher activity levels in the presence of woody understorey. NSL and P. pipistrellus also demonstrated more frequent commuting/roosting activity in sites without rhododendron, although P. pygmaeus and Myotis spp. appeared to be regularly utilising at least some rhododendron sites for this purpose. To mitigate potential negative effects of rhododendron removal on some bat species, we therefore suggest restriction of deer access to sites to enable recovery of native woody understorey.

Riparian Reserves Promote Insectivorous Bat Activity in Oil Palm Dominated Landscapes

The expansion of oil palm agriculture has contributed to biodiversity loss in Southeast Asia and elsewhere in the tropics. Riparian reserves (areas of native forest along waterways) have the potential to maintain forest biodiversity and associated ecological processes within these agricultural landscapes. Using acoustic sampling, we investigated the value of riparian reserves for insectivorous bats in oil palm plantations in Sabah, Malaysian Borneo. We compared general bat activity, foraging activity, and species occupancy between riparian areas in forest and riparian reserves in oil palm plantations. Overall bat activity varied little between riparian reserves in oil palm and riparian forest. Rather, activity was greatest in areas with a high forest canopy, irrespective of how much forest was available within or outside the riparian reserve. Bat foraging activity, as well as the occupancy of two species, was greatest in the forest sites, and while bats were detected in the oil palm riparian reserves, both foraging and occupancy were more associated with topographic ruggedness than forest amount or height. Our results indicate that habitat structure within riparian reserves may be more important than reserve size for supporting insectivorous bat diversity within oil palm landscapes. These findings provide important insights into the extent of the ecological benefits provided by conservation set-asides in forest-agricultural landscapes in the tropics.

Disentangling effects of local and landscape variables on attractiveness of restored gravel‐sand pits for bat foraging activities

AbstractDespite the impacts of extraction activities, quarries have great potential for conservation of biodiversity, and their restoration can be considered a major task in restoration ecology. A particularly important issue is to quantify the roles of the following various factors that may influence biodiversity and restoration success: (a) local variables, (b) landscape variables and (c) ecological management. Following a multi‐model inference, we identify which variables were the most useful predictors of bat activity in gravel‐sand pits. We used data from 21 French gravel‐sand pits provided by the biodiversity‐monitoring scheme, ROSELIERE. Our results suggest that within these restored gravel‐sand pits, landscape variables appear to be better predictors of the attractiveness of restored gravel‐sand pits for the foraging activity of bats than local variables. Species or community indexes appeared to be more sensitive to landscape variables measured at a large scale (i.e., 1,000 m). Among local variables, the time elapsed after operation was a better predictor of bat foraging activity than the description of the habitat itself. The effect was more obvious within a site with an elapsed time since operation greater than 10 years. Our findings suggest that to increase the attractiveness of gravel‐sand pits for bat foraging activities, planning policies should consider not only the intrinsic characteristics of a project (i.e., local variables) but also the surrounding environment (i.e., landscape variables).

Influences of Landscape Features on Bat Activity in North Dakota

ABSTRACTLand conversion and modification threatens many wildlife and plant species in the northern Great Plains, including bats. Our objective was to assess the association of bat species with landscape features in the northern Great Plains of North Dakota, USA, taking the first step towards understanding the habitat needs of bats in this region. We examined patterns of bat activity across different landscapes, identified those landscape features associated with high levels of bat activity, and determined which specific land features (i.e., vegetation and water types) were most commonly associated with each bat species. We used passive acoustic monitoring to measure bat activity at sites across North Dakota, and assessed detailed land characteristics at each site. We used nonmetric multidimensional scaling and multivariate regression tree analysis to examine relationships between bat activity and landscape variables. Bat foraging activity was influenced by structural landscape characteristics and the availability of specific water resources. High levels of bat activity were associated with riparian forested areas of varying structural complexity, ponds, and, to a lesser extent, open riparian lands. Individual bat species were influenced by land type and water resources differently. We identified big brown bats (Eptesicus fuscus) and little brown bats (Myotis lucifugus) as indicators of open riparian and pond landscapes, respectively. These results highlight the importance of prairie riparian landscapes and maintaining heterogeneity across the landscape for conservation and management of bat communities. Further, we identified ponds as an important landscape feature for little brown bats, a species of conservation concern, indicating that this specific feature should be a focus of conservation efforts on prairie wetlands. © 2019 The Wildlife Society.

Vertical stratification in foraging activity of Chaerephon plicatus (Molossidae, Chiroptera) in Central Thailand

Chaerephon plicatus consumes large amounts of planthoppers, which are the most serious pest in Asian rice fields. Brown planthoppers (Nilaparvata lugens) are known to migrate at high altitude and can cause severe damage and economic loss over a large area. However, we lack evidence whether this bat species also forage at high altitudes. This study investigated the stratification in foraging activity of C. plicatus at approximately 0, 100, and 200 m above ground level by using a helium-filled balloon-kite. The activity of C. plicatus aloft (100 m and 200 m) on average was six to twelve times higher than that close to the ground. Peak activity corresponded with the top of the nocturnal stable boundary layer, which is also the layer of maximum temperature and wind speed. Nilaparvata lugens has been found flying at the altitude where peak bat foraging activity occurs, which suggests that C. plicatus actively follows these migratory insects in the air. Thus, C. plicatus bats potentially play an important role in insect pest suppression in the areas they inhabit as well as at the landscape scale. However, the height of peak activity also corresponds with the height of wind turbine blades, thus, such turbines may pose a serious threat to the species.

The foraging activity of bats in managed pine forests of different ages

Temperate zone bats are associated with forests and affected by forest management practices. However, practices vary among regions and countries, and the relationship between bats and managed forest stands is not well understood. We compared the activity of bats in three forest management areas across four stand ages of managed Scots pine (Pinus sylvestris) in western Poland. Stand ages included clear-cut stands, young (2–5 year) stands, middle-aged (41–60 year) stands, and mature (> 80 years) stands. We sampled bat activity by walking transects with a broadband ultrasound Pettersson D-1000X detector. Across our study area, highest bat activity was in clear-cut and young stands and lowest in mature stands. Bat species adapted to foraging in open habitats had high activity in clear and young stands, while those adapted to closed habitats had high activity in middle-aged and mature stands. Our results suggest that the presence of mature pine forests is important for closed-habitat foragers, including rare and threatened bat species, and active management to increase mature forest areas is important. At the same time, a mosaic of different growth stages of stands can support high activity of open- and edge-habitat foragers.

Diversity and foraging activity of bats in cultivated and uncultivated areas in agroecosystems of a Mediterranean-climate hotspot

ABSTRACTBats are one of the least-studied vertebrate groups in Chile. We sampled six fruit farms in the Mediterranean-climate zone and three in a semiarid zone during 2015 and 2016, respectively. We assessed if activity (passes) and foraging (feeding buzzes) of bat species differed between cultivated and uncultivated intra-farm habitats. We found six bat species, all threatened and insectivorous. Tadarida brasiliensis was the most frequently recorded species. We found more activity and foraging in uncultivated than cultivated habitats in total, although the opposite trend was observed during springtime in semiarid region. More than a third of the bat passes were feeding buzzes in both habitats, suggesting the potential service to agriculture. Further investigation is needed to promote conservation of bats and their integration as biocontrols in agroecosystems in Chile.

Restoring historical fire regimes increases activity of endangered bats

BackgroundFire suppression has altered ecological communities globally. Prescribed fire regimes strive to restore function to these fire-dependent ecosystems by mimicking natural fire regimes. Although fire frequency is a widely acknowledged component of fire regimes, the importance of fire seasonality for biodiversity is less clear but appears to play a critical role for a variety of taxa, particularly in the North American Coastal Plain. In subtropical Florida, USA, fire historically occurred primarily at the transition from the dry to wet season (early wet season: April to June) when dry fuel accumulation coincides with a high incidence of lightning. We investigated the effects of fire frequency and season on endangered Florida bonneted bats (Eumops floridanus [G.M. Allen, 1932]), a species endemic to a region that evolved with frequent fires.ResultsWe surveyed bat activity acoustically in 149 sites in fire-dependent vegetation communities (pine flatwoods and prairies), and evaluated the effects of fire frequency and seasonality, using burn records from the previous 18 years. Variation in bat activity was best explained by both fire frequency and season: bat activity decreased with early wet season (April to June) burn interval and increased with dry season (November to March) burn interval. Bat activity and foraging activity were highest in sites burned at > 3- to 5-year intervals during the early wet season.ConclusionFires during the historic fire season at a moderate frequency (> 3 to 5 yr) appear to optimize habitat for bats in both pine flatwoods and prairies, likely through increases in roosts, flight space, and insect prey availability. It appears that Florida bonneted bats are fire-adapted and benefit from prescribed burn programs that closely mimic historical fire regimes. We encourage consideration of both fire frequency and seasonality when managing ecosystems with fire.

The importance of lakes for bat conservation in Amazonian rainforests: an assessment using autonomous recorders

AbstractRecent studies predict a future decrease in precipitation across the tropics, particularly the Amazon, likely causing significant droughts that have negative consequences for Amazonian freshwater biomes, especially lakes. Furthermore, immediate consequences of global warming for terrestrial fauna associated with tropical lakes are poorly understood as the vast majority of studies come from temperate regions. Here, we assess the seasonal importance of lakes for the conservation of aerial insectivorous bats in the Central Amazon using passive bat recorders. We compared richness, general bat activity and foraging activity between lakes and adjacent forest. Of a total of 21 species/sonotypes recorded in both habitats, all were detected over lakes, and 18 were significantly more active over lakes than in forest. Only two species had significantly higher activity levels in the forest than at the lakes. Species richness and general bat activity over the lakes were higher in the dry than in the rainy season. Foraging activity was also greater over the lakes than within the forest in both seasons. Moreover, both variables were positively correlated with lake size, although the effect on activity was species‐specific. Climate change‐driven shrinking of lakes may have detrimental consequences for aerial insectivorous bats, especially for the most water‐dependent species. Compared to permanent water bodies of other regions, the value of tropical lakes for functionally important taxa, such as bats, has been understudied. Higher bat activity levels over lakes than in forest in both seasons and comprising the whole ensemble of aerial insectivorous bats of the study region, indicate that lakes embedded in Amazonian terra firme forests deserve special attention for future bat conservation.

Tillage and herbicide reduction mitigate the gap between conventional and organic farming effects on foraging activity of insectivorous bats.

The increased use of pesticides and tillage intensification is known to negatively affect biodiversity. Changes in these agricultural practices such as herbicide and tillage reduction have variable effects among taxa, especially at the top of the trophic network including insectivorous bats. Very few studies compared the effects of agricultural practices on such taxa, and overall, only as a comparison of conventional versus organic farming without accurately accounting for underlying practices, especially in conventional where many alternatives exist. Divergent results founded in these previous studies could be driven by this lack of clarification about some unconsidered practices inside both conventional and organic systems. We simultaneously compared, over whole nights, bat activity on contiguous wheat fields of one organic and three conventional farming systems located in an intensive agricultural landscape. The studied organic fields (OT) used tillage (i.e., inversion of soil) without chemical inputs. In studied conventional fields, differences consisted of the following: tillage using few herbicides (T), conservation tillage (i.e., no inversion of soil) using few herbicides (CT), and conservation tillage using more herbicide (CTH), to control weeds. Using 64 recording sites (OT = 12; T = 21; CT = 13; CTH = 18), we sampled several sites per system placed inside the fields each night. We showed that bat activity was always higher in OT than in T systems for two (Pipistrellus kuhlii and Pipistrellus pipistrellus) of three species and for one (Pipistrellus spp.) of two genera, as well as greater species richness. The same results were found for the CT versus T system comparison. CTH system showed higher activity than T for only one genus (Pipistrellus spp.). We did not detect any differences between OT and CT systems, and CT showed higher activity than CTH system for only one species (Pipistrellus kuhlii). Activity in OT of Pipistrellus spp. was overall 3.6 and 9.3 times higher than CTH and T systems, respectively, and 6.9 times higher in CT than T systems. Our results highlight an important benefit of organic farming and contrasted effects in conventional farming. That there were no differences detected between the organic and one conventional system is a major result. This demonstrates that even if organic farming is presently difficult to implement and requires a change of economic context for farmers, considerable and easy improvements in conventional farming are attainable, while maintaining yields and approaching the ecological benefits of organic methods.