Modifications of erythrocyte membrane hydration induced by organic tin compounds

A study on the effects of selected organic chlorides of tin on the extent of hydration of the lipid bilayer of erythrocyte ghosts from pig blood is presented. The following compounds were used, dibutyltin dichloride (DBT), tributyltin chloride (TBT), diphenyltin dichloride (DPhT) and triphenyltin chloride (TPhT). The degree of membrane hydration was measured by the ATR FTIR technique, which makes it possible to estimate the level of carbonyl and phosphate group hydration in lipids of membranes. Other measurements were made with a fluorescence technique involving a laurdan probe. Tin organic compounds caused dehydration of the lipid bilayer of ghosts in the region of the carbonyl groups. DBT and TBT produced weak dehydration in the region of the phosphate group, whereas DPhT and TPhT increased hydration. The results allow one to determine the location of organotin compounds within a membrane, and show that TBT penetrates the membrane the deepest and DBT the shallowest. Phenyl tin compounds penetrate membranes to an intermediate depth. The results obtained indicate that the destructive properties of the organometallic compounds depend mostly on their effect on hydration of the membrane.     

The trans-boundary importance of artificial bat hibernacula in managed European forests

Many European migratory bat species hibernate in large hollow trees, a decreasing resource in present day silviculture. Here, we report on the importance of man-made hibernacula to support trans-boundary populations of noctule bats (Nyctalus noctula), a species that performs seasonal long distance movements throughout Europe. In winter, we surveyed nine bat roosts (eight artificial and one natural) in Germany and collected small tufts of fur from a total of 608 individuals. We then measured the stable isotope ratios of the non-exchangeable hydrogen in fur keratin and estimated the origin of migrants using a refined isoscape origin model that included information on expected flight distances and migration directions. According to the stable isotope signature, 78 % of hibernating bats originated from local populations. The remaining 22 % of hibernacula occupants originated from distant populations, mostly from places in northern or eastern countries such as Sweden, Poland and Baltic countries. Our results confirm that many noctule bats cross one or several political borders during migration. Data on the breeding origin of hibernating noctule bats also suggest that artificial roosts may not only be important for local but also for distant populations. Protection of natural and artificial hibernacula in managed forests may support the trans-boundary populations of migratory bats when hollow trees are scarce in managed forests.     

Enhanced Passive Bat Rabies Surveillance in Indigenous Bat Species from Germany - A Retrospective Study

In Germany, rabies in bats is a notifiable zoonotic disease, which is caused by European bat lyssaviruses type 1 and 2 (EBLV-1 and 2), and the recently discovered new lyssavirus species Bokeloh bat lyssavirus (BBLV). As the understanding of bat rabies in insectivorous bat species is limited, in addition to routine bat rabies diagnosis, an enhanced passive surveillance study, i.e. the retrospective investigation of dead bats that had not been tested for rabies, was initiated in 1998 to study the distribution, abundance and epidemiology of lyssavirus infections in bats from Germany. A total number of 5478 individuals representing 21 bat species within two families were included in this study. The Noctule bat (Nyctalus noctula) and the Common pipistrelle (Pipistrellus pipistrellus) represented the most specimens submitted. Of all investigated bats, 1.17% tested positive for lyssaviruses using the fluorescent antibody test (FAT). The vast majority of positive cases was identified as EBLV-1, predominately associated with the Serotine bat (Eptesicus serotinus). However, rabies cases in other species, i.e. Nathusius'' pipistrelle bat (Pipistrellus nathusii), P. pipistrellus and Brown long-eared bat (Plecotus auritus) were also characterized as EBLV-1. In contrast, EBLV-2 was isolated from three Daubenton''s bats (Myotis daubentonii). These three cases contribute significantly to the understanding of EBLV-2 infections in Germany as only one case had been reported prior to this study. This enhanced passive surveillance indicated that besides known reservoir species, further bat species are affected by lyssavirus infections. Given the increasing diversity of lyssaviruses and bats as reservoir host species worldwide, lyssavirus positive specimens, i.e. both bat and virus need to be confirmed by molecular techniques.     

Oceanic records of North American bats and implications for offshore wind energy development in the United States

Offshore wind energy is a growing industry in the United States, and renewable energy from offshore wind is estimated to double the country''s total electricity generation. There is growing concern that land‐based wind development in North America is negatively impacting bat populations, primarily long‐distance migrating bats, but the impacts to bats from offshore wind energy are unknown. Bats are associated with the terrestrial environment, but have been observed over the ocean. In this review, we synthesize historic and contemporary accounts of bats observed and acoustically recorded in the North American marine environment to ascertain the spatial and temporal distribution of bats flying offshore. We incorporate studies of offshore bats in Europe and of bat behavior at land‐based wind energy studies to examine how offshore wind development could impact North American bat populations. We find that most offshore bat records are of long‐distance migrating bats and records occur during autumn migration, the period of highest fatality rates for long‐distance migrating bats at land‐based wind facilities in North America. We summarize evidence that bats may be attracted to offshore turbines, potentially increasing their exposure to risk of collision. However, higher wind speeds offshore can potentially reduce the amount of time that bats are exposed to risk. We identify knowledge gaps and hypothesize that a combination of operational minimization strategies may be the most effective approach for reducing impacts to bats and maximizing offshore energy production.     

Wind Farm Facilities in Germany Kill Noctule Bats from Near and Far

Over recent years, it became widely accepted that alternative, renewable energy may come at some risk for wildlife, for example, when wind turbines cause large numbers of bat fatalities. To better assess likely populations effects of wind turbine related wildlife fatalities, we studied the geographical origin of the most common bat species found dead below German wind turbines, the noctule bat (Nyctalus noctula). We measured stable isotope ratios of non-exchangeable hydrogen in fur keratin to separate migrants from local individuals, used a linear mixed-effects model to identify temporal, spatial and biological factors explaining the variance in measured stable isotope ratios and determined the geographical breeding provenance of killed migrants using isoscape origin models. We found that 72% of noctule bat casualties (n = 136) were of local origin, while 28% were long-distance migrants. These findings highlight that bat fatalities at German wind turbines may affect both local and distant populations. Our results indicated a sex and age-specific vulnerability of bats towards lethal accidents at turbines, i.e. a relatively high proportion of killed females were recorded among migratory individuals, whereas more juveniles than adults were recorded among killed bats of local origin. Migratory noctule bats were found to originate from distant populations in the Northeastern parts of Europe. The large catchment areas of German wind turbines and high vulnerability of female and juvenile noctule bats call for immediate action to reduce the negative cross-boundary effects of bat fatalities at wind turbines on local and distant populations. Further, our study highlights the importance of implementing effective mitigation measures and developing species and scale-specific conservation approaches on both national and international levels to protect source populations of bats. The efficacy of local compensatory measures appears doubtful, at least for migrant noctule bats, considering the large geographical catchment areas of German wind turbines for this species.     

The Speciation of Organotin Compounds in Sediment and Water Samples from the Port of Gdynia

Organotin compounds (OTC) are toxic towards all living organisms. The application of organitin-based antifouling systems is becoming the main source of OTC in the ocean. Harbor sediments and water contain large deposits of organotin compounds due to application of antifouling systems in the shipping industry. OTC contamination presents a potential risk to the marine environment.

Sediment and water samples were collected in 2009 from Gdynia Harbor. For all the analyzed organotin compounds, the mean concentration values were determined: water samples monobutyltin (MBT): 13.2, dibutyltin (DBT): 16.7, tributyltin (TBT): 60.7 (ng cation dm^?3), and sediment samples MBT: 261.4, DBT: 751.9, TBT: 2148.2 (ng cation g^?1 d.w.). The estimated content of monophenyltin (MPhT), diphenyltin (DPhT), triphenyltin (TPhT), monooctyltin (MOT), dioctyltin (DOT), and tricyclohexyltin (TCHT) were below the detection limit of the applied method. It was found that the content of organic matter, the amount of fine fraction, and the pH all play a significant role in the distribution and sorption process of OTC between the water and the sediment on the bottom. Compared to an earlier study, the concentrations of all OTC are much lower, confirming that the applied legislation has had a positive impact.     

Effects of butyltins and inorganic tin on chemotaxis of aquatic bacteria

Summary Tributyltin (TBT) and its degradation products dibutyltin (DBT), monobutyltin (MBT) and Sn^IV were toxic toPseudomonas fluorescens SHC-6 andSerratia sp. Gil-1 with EC₅₀ values in the range of 10^–3 to 10^–4M. These four compounds were negative chemotactic agents forP. fluorescens, and the butyltins were negatively chemotactic forSerratia sp. at concentrations over four orders of magnitude lower than the EC₅₀ values.l-Aspartate was a positive chemotactic agent for both organisms. TBT, DBT and MBT negated the effect ofl-aspartate onP. fluorescens but not onSerratia sp. Thus, TBT has the potential to affect microbial populations at concentrations much lower than those which prevent growth, and degradation of TBT does not always detoxify it. SnCl₄ was less toxic than TBT or DBT to these organisms and it was not chemotactic forSerratia sp. Gil-1. Tributylamine and tributylphosphate were less than 1/10th as toxic as TBT and they did not have a chemotactic effect on either organism at concentrations at which TBT had a significant effect. Therefore, both the Sn-and butyl-moieties contribute to the toxic and chemotactic properties of TBT.     

Inhibition of human cytochrome P450 aromatase activity by butyltins

Organotin compounds are widely used as antifouling agents and bioaccumulate in the food chain. Tributyltin chloride (TBT) has been shown to induce imposex in female gastropods. On the basis of this observation it has been suggested that TBT acts as an endocrine disrupter inhibiting the conversion of androgens to estrogens mediated by the aromatase cytochrome P450 enzyme. However, to date, the molecular basis of TBT-induced imposex and in particular its putative inhibitory effects on human aromatase cytochrome P450 activity have not been investigated. Therefore, we examined the effects of the organotin compounds tetrabutyltin (TTBT), TBT, dibutyltin dichloride (DBT) and monobutyltin trichloride (MBT) on human placental aromatase activity. TBT was found to be a partial competitive inhibitor of aromatase activity with an IC(50) value of 6.2 microM with 0.1 microM androstenedione as substrate. TBT impaired the affinity of the aromatase to androstenedione but did not affect electron transfer from NADPH to aromatase via inhibiting the NADPH reductase. DBT acted as a partial but less potent inhibitor of human aromatase activity (65% residual activity), whereas TTBT and MBT had no effect. The residual activity of TBT-saturated aromatase was 37%. In contrast, human 3beta-HSD type I activity was only moderately inhibited by TBT (80% residual activity). Moreover, neither TTBT or DBT nor MBT inhibited the 3beta-HSD type I activity. Together, these results suggest that the environmental pollutants TBT and DBT, both present in marine organisms, textile and plastic products, may have specific impacts on the metabolism of sex hormones in humans.     

Tributyltin and triphenyltin inhibit osteoclast differentiation through a retinoic acid receptor-dependent signaling pathway

Organotin compounds, such as tributyltin (TBT) and triphenyltin (TPT), have been widely used in agriculture and industry. Although these compounds are known to have many toxic effects, including endocrine-disrupting effects, their effects on bone resorption are unknown. In this study, we investigated the effects of organotin compounds, such as monobutyltin (MBT), dibutyltin (DBT), TBT, and TPT, on osteoclast differentiation using mouse monocytic RAW264.7 cells. MBT and DBT had no effects, whereas TBT and TPT dose-dependently inhibited osteoclast differentiation at concentrations of 3-30 nM. Treatment with a retinoic acid receptor (RAR)-specific antagonist, Ro41-5253, restored the inhibition of osteoclastogenesis by TBT and TPT. TBT and TPT reduced receptor activator of nuclear factor-kappaB ligand (RANKL) induced nuclear factor of activated T cells (NFAT) c1 expression, and the reduction in NFATc1 expression was recovered by Ro41-5253. Our results suggest that TBT and TPT suppress osteoclastogenesis by inhibiting RANKL-induced NFATc1 expression via an RAR-dependent signaling pathway.     

Differences in seasonal survival suggest species‐specific reactions to climate change in two sympatric bat species

Long‐lived animals with a low annual reproductive output need a long time to recover from population crashes and are, thus, likely to face high extinction risk, if the current global environmental change will increase mortality rates. To aid conservation of those species, knowledge on the variability of mortality rates is essential. Unfortunately, however, individual‐based multiyear data sets that are required for that have only rarely been collected for free‐ranging long‐lived mammals. Here, we used a five‐year data set comprising activity data of 1,445 RFID‐tagged individuals of two long‐lived temperate zone bat species, Natterer's bats (Myotis nattereri) and Daubenton's bats (Myotis daubentonii), at their joint hibernaculum. Both species are listed as being of high conservation interest by the European Habitats Directive. Applying mixed‐effects logistic regression, we explored seasonal survival differences in these two species which differ in foraging strategy and phenology. In both species, survival over the first winter of an individual's life was much lower than survival over subsequent winters. Focussing on adults only, seasonal survival patterns were largely consistent with higher winter and lower summer survival but varied in its level across years in both species. Our analyses, furthermore, highlight the importance of species‐specific time periods for survival. Daubenton's bats showed a much stronger difference in survival between the two seasons than Natterer's bats. In one exceptional winter, the population of Natterer's bats crashed, while the survival of Daubenton's bats declined only moderately. While our results confirm the general seasonal survival pattern typical for hibernating mammals with higher winter than summer survival, they also show that this pattern can be reversed under particular conditions. Overall, our study points toward a high importance of specific time periods for population dynamics and suggests species‐, population‐, and age class‐specific responses to global climate change.     

Use of Olfaction During Prey Location by the Common Vampire Bat (Desmodus rotundus)1

The common vampire bat, Desmodus rotundus, feeds on mammalian blood and is a major agricultural pest in Latin America. One way to prevent bats from biting livestock is to understand how the bats locate the livestock. We confirmed the role of olfaction in foraging with a modified cafeteria trial. Bats significantly favored blood meals associated with scent (fur, feces) over meals lacking these olfactory cues. These results confirm earlier observations on the role of olfaction during prey location by this species, and have potential to facilitate eradication measures without extensive loss of other bat species.     

Organotin in the Tagus estuary

The tri(n-butyl)tin (TBT) moiety has been shown to have complex ecotoxicological effects on estuarine populations. In the Tagus the massive die-off of the Portuguese oyster (Crassostrea angulata Lmk), has been attributed to the introduction and use of this contaminant by shipyards. This paper reviews previous work by others and reassesses our results obtained in water and sediments of the Tagus estuary, as a contribution to the understanding of tin geochemistry and organotin speciation in this estuary. Contrary to earlier results, the latest surveys show that in the open waters of the Tagus measurable concentrations of all the three butyltin species occur, exhibiting peak concentrations at two locations that indicate two previously undetected sources of TBT. TBT also presents a peak concentration in sediments near the Lisnave shipyards, as previously suggested. The latest surveys still detected methylated forms of tin, particularly monomethyltin (Me Sn³⁺), in Tagus sediments, with maximum concentrations in the vicinity of urban effluent discharges. The concentrations for TBT and its degradation products found in the Tagus are potentially harmful to the populations of gastropods and endemic bivalves.     

Feeding adaptations in the hairs and tongues of nectar-feeding bats.

Scales on the hairs of pollinating bats spread out at an angle to the main hair shaft. In contrast, the hairs of most bats not associated with plants are relatively smooth. Both megachiropteran and microchiropteran flower-feeding bats show this divaricate scale structure which may aid in the collection of a heavy coating of pollen. Some of the pollen is transferred to subsequent flowers, but most is groomed from the fur and ingested as the only reliable nitrogen source for the bat. The tongues of nectar-feeding bats also show structural modifications which allow efficient uptake of the carbohydrate fraction of the diet. Structural specializations of the hiars and tongue are analogous to those seen in other nectar-feeding animals.     

Interspecific variation in redox status regulation and immune defence in five bat species: the role of ectoparasites

Harmful reactive oxygen species (ROS) produced during metabolism and immune responses are neutralized in part by a powerful enzymatic antioxidant system. Inter-species variability in the baseline activity of antioxidant enzymes may be explained by a variety of life history traits. For instance, ectoparasites can elicit repeated immune responses, thus increasing the production of reactive oxygen species. The bat species studied so far have been acknowledged to have effective antioxidant defences. However, interspecific comparisons within the clade do not exist. The present study compares the antioxidant defence and immune function activities in five northern boreal bat species relative to their ectoparasite prevalence and intensity (wing mites and louse flies) to reveal inter-species differences. Antioxidant enzyme and immune defense activities, which differ between species, are positively associated, with total ectoparasite (mites and bat flies) frequencies, total ROS, and protein carbonylation in Daubenton’s bats, but enzyme activities are also independently influenced by sampling date with activities increasing towards the autumn. Antioxidant activities are also positively associated with total reactive oxygen species and oxidative damage (protein carbonylation) in the Daubenton’s bat. Our results suggest that antioxidant activities are associated with ecological factors such as parasite load and season, and we consider it likely that these may partly explain the observed interspecific variation.     

Hibernating Little Brown Myotis (Myotis lucifugus) Show Variable Immunological Responses to White-Nose Syndrome

White-nose syndrome (WNS) is an emerging infectious disease devastating hibernating North American bat populations that is caused by the psychrophilic fungus Geomyces destructans. Previous histopathological analysis demonstrated little evidence of inflammatory responses in infected bats, however few studies have compared other aspects of immune function between WNS-affected and unaffected bats. We collected bats from confirmed WNS-affected and unaffected sites during the winter of 2008–2009 and compared estimates of their circulating levels of total leukocytes, total immunoglobulins, cytokines and total antioxidants. Bats from affected and unaffected sites did not differ in their total circulating immunoglobulin levels, but significantly higher leukocyte counts were observed in bats from affected sites and particularly in affected bats with elevated body temperatures (above 20°C). Bats from WNS-affected sites exhibited significantly lower antioxidant activity and levels of interleukin-4 (IL-4), a cytokine that induces T cell differentiation. Within affected sites only, bats exhibiting visible fungal infections had significantly lower antioxidant activity and levels of IL-4 compared to bats without visible fungal infections. Overall, bats hibernating in WNS-affected sites showed immunological changes that may be evident of attempted defense against G. destructans. Observed changes, specifically elevated circulating leukocytes, may also be related to the documented changes in thermoregulatory behaviors of affected bats (i.e. increased frequencies in arousal from torpor). Alterations in immune function may reflect expensive energetic costs associated with these processes and intrinsic qualities of the immunocapability of hibernating bats to clear fungal infections. Additionally, lowered antioxidant activity indicates a possible imbalance in the pro- versus antioxidant system, may reflect oxidative tissue damage, and should be investigated as a contributor to WNS-associated morbidity and mortality.     

Investigating cat predation as the cause of bat wing tears using forensic DNA analysis

Cat predation upon bat species has been reported to have significant effects on bat populations in both rural and urban areas. The majority of research in this area has focussed on observational data from bat rehabilitators documenting injuries, and cat owners, when domestic cats present prey. However, this has the potential to underestimate the number of bats killed or injured by cats. Here, we use forensic DNA analysis techniques to analyze swabs taken from injured bats in the United Kingdom, mainly including Pipistrellus pipistrellus (40 out of 72 specimens). Using quantitative PCR, cat DNA was found in two‐thirds of samples submitted by bat rehabilitators. Of these samples, short tandem repeat analysis produced partial DNA profiles for approximately one‐third of samples, which could be used to link predation events to individual cats. The use of genetic analysis can complement observational data and potentially provide additional information to give a more accurate estimation of cat predation.     

Habitat usage of Daubenton's bat (Myotis daubentonii), common pipistrelle (Pipistrellus pipistrellus), and soprano pipistrelle (Pipistrellus pygmaeus) in a North Wales upland river catchment

Distributions of Daubenton's bat (Myotis daubentonii), common pipistrelle, (Pipistrellus pipistrellus), and soprano pipistrelle (Pipistrellus pygmaeus) were investigated along and altitudinal gradient of the Lledr River, Conwy, North Wales, and presence assessed in relation to the water surface condition, presence/absence of bank‐side trees, and elevation. Ultrasound recordings of bats made on timed transects in summer 1999 were used to quantify habitat usage. All species significantly preferred smooth water sections of the river with trees on either one or both banks; P. pygmaeus also preferred smooth water with no trees. Bats avoided rough and cluttered water areas, as rapids may generate high‐frequency echolocation‐interfering noise and cluttered areas present obstacles to flight. In lower river regions, detections of bats reflected the proportion of suitable habitat available. At higher elevations, sufficient habitat was available; however, bats were likely restricted due to other factors such as a less predictable food source. This study emphasizes the importance of riparian habitat, bank‐side trees, and smooth water as foraging habitat for bats in marginal upland areas until a certain elevation, beyond which bats in these areas likely cease to forage. These small‐scale altitudinal differences in habitat selection should be factored in when designing future bat distribution studies and taken into consideration by conservation planners when reviewing habitat requirements of these species in Welsh river valleys, and elsewhere within the United Kingdom.     

Changes in hibernating tricolored bat (Perimyotis subflavus) roosting behavior in response to white‐nose syndrome

Understanding animals'' behavioral and physiological responses to pathogenic diseases is critical for management and conservation. One such disease, white‐nose syndrome (WNS), has greatly affected bat populations throughout eastern North America leading to significant population declines in several species. Although tricolored bat (Perimyotis subflavus) populations have experienced significant declines, little research has been conducted on their responses to the disease, particularly in the southeastern United States. Our objective was to document changes in tricolored bat roost site use after the appearance of WNS in a hibernaculum in the southeastern U.S. and relate these to microsite temperatures, ambient conditions, and population trends. We censused a tricolored bat hibernaculum in northwestern South Carolina, USA, once each year between February 26 and March 2, 2014–2021, and recorded species, section of the tunnel, distance from the entrance, and wall temperature next to each bat. The number of tricolored bats in the hibernaculum dropped by 90.3% during the first 3 years after the arrival of WNS. However, numbers stabilized and slightly increased from 2018 to 2021. Prior to the arrival of WNS, 95.6% of tricolored bats roosted in the back portion of the tunnel that was the warmest. After the arrival of WNS, we observed a significant increase in the proportion of bats using the front, colder portions of the tunnel, particularly during the period of population stabilization and increase. Roost temperatures of bats were also positively associated with February external temperatures. Our results suggest that greater use of the colder sections of the tunnel by tricolored bats could have led to increased survival due to slower growth rates of the fungus that causes WNS in colder temperatures or decreased energetic costs associated with colder hibernation temperatures. Thus, management actions that provide cold hibernacula may be an option for long‐term management of hibernacula, particularly in southern regions.     

Signs of a vector's adaptive choice: on the evasion of infectious hosts and parasite‐induced mortality

Laboratory and field experiments have demonstrated in many cases that malaria vectors do not feed randomly, but show important preferences either for infected or non‐infected hosts. These preferences are likely in part shaped by the costs imposed by the parasites on both their vertebrate and dipteran hosts. However, the effect of changes in vector behaviour on actual parasite transmission remains a debated issue. We used the natural associations between a malaria‐like parasite Polychromophilus murinus, the bat fly Nycteribia kolenatii and a vertebrate host the Daubenton's bat Myotis daubentonii to test the vector's feeding preference based on the host's infection status using two different approaches: 1) controlled behavioural assays in the laboratory where bat flies could choose between a pair of hosts; 2) natural bat fly abundance data from wild‐caught bats, serving as an approximation of realised feeding preference of the bat flies. Hosts with the fewest infectious stages of the parasite were most attractive to the bat flies that did switch in the behavioural assay. In line with the hypothesis of costs imposed by parasites on their vectors, bat flies carrying parasites had higher mortality. However, in wild populations, bat flies were found feeding more based on the bat's body condition, rather than its infection level. Though the absolute frequency of host switches performed by the bat flies during the assays was low, in the context of potential parasite transmission they were extremely high. The decreased survival of infected bat flies suggests that the preference for less infected hosts is an adaptive trait. Nonetheless, other ecological processes ultimately determine the vector's biting rate and thus transmission. Inherent vector preferences therefore play only a marginal role in parasite transmission in the field. The ecological processes rather than preferences per se need to be identified for successful epidemiological predictions.     

Using echolocation monitoring to model bat occupancy and inform mitigations at wind energy facilities

Fatalities of migratory bats, many of which use low frequency (<35 kHz; LowF) echolocation calls, have become a primary environmental concern associated with wind energy development. Accordingly, strategies to improve compatibility between wind energy development and conservation of bat populations are needed. We combined results of continuous echolocation and meteorological monitoring at multiple stations to model conditions that explained presence of LowF bats at a wind energy facility in southern California. We used a site occupancy approach to model nightly LowF bat presence while accounting for variation in detection probability among echolocation detectors and heights. However, we transposed the spatial and temporal axes of the conventional detection history matrix such that occupancy represented proportion of nights, rather than monitoring points, on which LowF bats were detected. Detectors at 22 m and 52 m above ground had greater detection probabilities for LowF bats than detectors at 2 m above ground. Occupancy of LowF bats was associated with lower nightly wind speeds and higher nightly temperatures, mirroring results from other wind energy facilities. Nevertheless, we found that building separate models for each season and considering solutions with multiple covariates resulted in better fitting models. We suggest that use of multiple environmental variables to predict bat presence could improve efficiency of turbine operational mitigations (e.g., changes to cut-in speeds) over those based solely on wind speed. Increased mitigation efficiencies could lead to greater use of mitigations at wind energy facilities with benefits to bat populations. © 2011 The Wildlife Society.