Tadarida Brasiliensis Research Articles

Distributional patterns of the Brazilian free-tailed bat Tadarida brasiliensis in the Peruvian territory

The molossid bat Tadarida brasiliensis has a wide and apparently continuous distribution in South America. Although it has been reported in several localities of both versants of the Peruvian Andes, the potential distribution for this species has not been formally analyzed. Therefore, we describe its distributional pattern in the territory and provide comments about the possible influence of the Andes in its distribution. We gathered occurrence records from museums, acoustic surveys, literature, GBIF and Vertnet sources, and we selected localities to minimize spatial correlation. After defining a minimum-convex polygon of Peruvian records as background area, we use Maxent software with bioclimatic variables to construct species distribution models. Several models were evaluated using different metrics, and the model with the lowest AICc was selected. Then, the model was projected for Peruvian territory. Tadarida brasiliensis is reported for the first time in Cajamarca, Piura and Ica departments. The potential distribution model showed two disjunct suitable areas, one for the Pacific versant and other for the Amazonian versant of the Andes, but connected with moderate suitable conditions in the Huancabamba Depression region in northern Peru. Mean diurnal range and annual mean temperature were identified as the main limiting factors for the potential distribution of this species in this territory. Tadarida brasiliensis exhibits a discontinuous distribution in the Peruvian territory. In northern part, the Huancabamba depression zone has climatic conditions that may allow the east-west dispersal for this species. In central and southern parts, the higher crest of the Andes (> 4,500 m) has low suitable conditions due to the extreme climate. In the eastern, the lowland Amazonian forests has low suitability for this species, probably due to high temperatures. We suggest that the Andes could be acting a biogeographical barrier that limits the dispersal for this species, but population-genetic studies are needed to confirm this hypothesis. We identified that temperature is the main climatic factor that limit the dispersal of this bat. In conclusion, T. brasiliensis is mainly associated with desert and Andean slopes ecosystems in Peru, and we highlight the importance of incorporating acoustic records in the analysis of its distribution patterns.

Helminth Fauna of Tadarida brasiliensis (Mammalia, Chiroptera) in the State of Rio Grande do Sul, Brasil: A Comparative Approach

Chiroptera is the second largest order of mammals in terms of species richness, yet little data are available on the helminth fauna infecting bats. The goal of this paper was therefore to describe the helminth fauna of a common bat species from the Brazilian state of Rio Grande do Sul. We collected 63 individuals of the bat Tadarida brasiliensis in the municipality of Montenegro in March 2015 (33 males and 30 females; 41 adults and 22 juveniles). We identified 451 endoparasites belonging to eight species (i.e. Urotrema scabridum, Limatulum oklahomense, Postorchigenes paraguayensis, Parabascus limatulus, Ochoterenatrema sp., Vampirolepis decipiens, Tadaridanema delicatus, as well as one unidentified species representing the superfamily Microphalloidea). Based on their importance value, we classified two helminth species as ‘dominant’, four as ‘co-dominant’ and two as ‘subordinate'. Vampirolepis decipiens had both the highest prevalence (of 55.5%) and greatest abundance (3.52 parasites/host). We report for the first time P. limatulus in T. brasiliensis in Rio Grande do Sul. This study provides important base-line data to elucidate helminth infestations in T. brasiliensis in Brazil.

Different as night and day: wild bats modify echolocation in complex environments when visual cues are present

Many animals rely on the integration of senses to interact with their environment. While most studies on multisensory integration focus on animals that use passive sensing, fewer studies have investigated actively sensing animals, such as animals that use echolocation. Prior work has demonstrated that bats and dolphins have the ability to perceive objects through both echolocation and vision and may integrate information across senses to improve target identification. Less is known, however, about how these animals might modify their active sensing systems when additional sensory input, such as visual cues, is available. In this study, we examine how Brazilian free-tailed bats, Tadarida brasiliensis, in the wild use their echolocation calls during night compared to day under two different sensory challenges: ground detection in an open field and roost localization in a complex and cluttered environment at a cave edge. Both location and light condition had a significant effect on call frequency and call duration. Echolocation calls had shorter durations and wider bandwidths during night compared to day, and this effect was more pronounced during roost localization at the complex cave edge. These results suggest that bats may use vision to supplement echolocation, but modifications to their sensing systems may depend on environmental complexity and/or sensorimotor challenges.

Species-specific effects of moonlight on insectivorous bat activity in central Chile

Abstract Moonlight intensity influences the activity patterns of bats. Some bat species reduce their activity levels during brighter nights, a phenomenon known as “lunar phobia.” While lunar phobia of bats has been extensively studied in tropical regions, the same is not the case of bats in temperate regions. By using acoustic detectors, we examined differences in the activity of insectivorous bats on nights with different moonlight intensity in an agricultural landscape of central Chile. We also examined the hourly activity patterns throughout the night and how these varied between full and new moon nights. All bat species modified their activity based on the moonlight intensity; however, their effects were species-specific. The activity of Lasiurus varius, L. villosissimus, Myotis chiloensis, and Histiotus montanus was lower during bright nights, while Tadarida brasiliensis was the only species whose activity was higher during bright nights. Hourly activity throughout the night differed between full moon nights and new moon nights in most bat species. During full moon, bats concentrated their activities in the early hours of the nights; a more homogeneous activity pattern was exhibited during new moon night. Our study demonstrates that moonlight affects the activity of bats in Chile, a factor that should be considered when studying bats.

First record of Urotrema scabridum (Platyhelminthes), and new records of helminths of Tadarida brasiliensis from Mexican Plateau

The Mexican free-tailed bat ( Tadarida brasiliensis ) is an abundant, widely distributed species in Mexico, except for most of the Yucatán peninsula. We studied the helminth fauna of T. b. mexicana at seven localities in the State of Zacatecas in order to advance the knowledge of helminth parasites of wild vertebrates in northern-central Mexico. Eighty-four bat specimens were examined for the presence of helminth parasites following standard procedures; helminths found were identified and infections were characterized. Of the specimens examined, 65.47 % were parasitized. The helminth fauna comprises five taxa: three digeneans ( Dicrocoelium rileyi , Ochoterenatrema labda , and Urotrema scabridum ); one cestode ( Vampirolepis sp.); and one nematode ( Tadaridanema delicatus ). We present a brief morphological description of Urotrema scabridum . D. rileyi was the most prevalent and abundant helminth species. The intestine was the habitat most parasitized, with four species. Indirect life cycles predominate, and are related to the insectivorous habits of this host. Further studies on this host-parasite system are necessary to contribute to population monitoring and conservation; biogeographic patterns of helminth parasites of bats should also be studied to explore their origins and evolution in the region. U. scabridum is reported for the first time from Zacatecas. All species are new locality records.

Ultrasonic acoustic deterrents significantly reduce bat fatalities at wind turbines

Wind turbines are known to cause bat fatalities worldwide. Ultrasonic acoustic deterrents are a potential solution to reduce impacts on bats, but few experimental field studies have been conducted at utility scale wind energy facilities. Our objective was to assess effectiveness of a recently developed deterrent for reducing bat fatalities at wind turbines in southern Texas, USA. We quantified fatalities at control (deterrents off) and treatment (deterrents on) wind turbines from 31 July through 30 October in 2017 and 2018, and assessed deterrent effectiveness using generalized linear mixed models. Our results indicate deterrents significantly reduced bat fatalities for Lasiurus cinereus and Tadarida brasiliensis by 78% and 54%, respectively. We observed no significant reduction in fatalities for other species in the genus Lasiurius. Thus, deterrents represent a potential impact reduction strategy for some bat species, but research is still warranted to improve species-specific effectiveness.

Perceptions and attitudes of the local people towards bats in the surroundings of the Escaba dam (Tucumán, Argentina)

When biodiversity conservation of non-charismatic species is a priority, local people perception and value attributed to species are of vital importance. The presence of a huge colony of bats ( Tadarida brasiliensis ) in the Escaba dam located at the Yungas forest is an emblematic case for the conservation of bats in Argentina. The objective of this study was to evaluate the perception and attitude about the bats of the people living around the Escaba dam in order to redirect conservation efforts and education plans. Semi-structured surveys and participant observation were used to survey the information; and generalized linear models to analyze. The local inhabitants do not recognize the diversity of bat species, and mention only blood-sucking and insectivorous bats. The results show a positive trend in perception and attitude, influenced by the recognition of the role of bats as insect controllers and a feeling of identity generated by the colony. The perception becomes more positive as age advances and in those who reached the secondary level of education. New ways of measuring perception and attitude are presented, such as describing the forms of bat exclusion. All this must be taken into account in the development of the management plan, which should consider the possible local use of guano as a fertilizer, sustainable tourism and educational actions aiming at differentiating the species (i.e. this is not an hematophagous bat colony), the role of the colony at controlling possible diseases and the ecosystem services associated with these species.

A Preliminary Study of the Virome of the South American Free-Tailed Bats (Tadarida brasiliensis) and Identification of Two Novel Mammalian Viruses.

Bats provide important ecosystem services as pollinators, seed dispersers, and/or insect controllers, but they have also been found harboring different viruses with zoonotic potential. Virome studies in bats distributed in Asia, Africa, Europe, and North America have increased dramatically over the past decade, whereas information on viruses infecting South American species is scarce. We explored the virome of Tadarida brasiliensis, an insectivorous New World bat species inhabiting a maternity colony in Rosario (Argentina), by a metagenomic approach. The analysis of five pooled oral/anal swab samples indicated the presence of 43 different taxonomic viral families infecting a wide range of hosts. By conventional nucleic acid detection techniques and/or bioinformatics approaches, the genomes of two novel viruses were completely covered clustering into the Papillomaviridae (Tadarida brasiliensis papillomavirus type 1, TbraPV1) and Genomoviridae (Tadarida brasiliensis gemykibivirus 1, TbGkyV1) families. TbraPV1 is the first papillomavirus type identified in this host and the prototype of a novel genus. TbGkyV1 is the first genomovirus reported in New World bats and constitutes a new species within the genus Gemykibivirus. Our findings extend the knowledge about oral/anal viromes of a South American bat species and contribute to understand the evolution and genetic diversity of the novel characterized viruses.

Insectivorous bats as biomonitor of metal exposure in the megalopolis of Mexico and rural environments in Central Mexico

The Megalopolis of Mexico is one of the largest cities in the world and presents substantial problems of metal pollution. Insectivorous bats that inhabit this city are potentially exposed to metals and could therefore serve as a good biomonitor. We collected 70 adult male individuals of Tadarida brasiliensis (Chiroptera: Molossidae) from two areas inside the Megalopolis (Cuautitlán and Xochimilco) and two rural environments in Central Mexico (Tequixquiac and Tlalcozotitlán). We analyzed livers to determine the total concentrations of ten metals by the ICP-MS technique, compared concentrations among study sites to provide evidence of metal exposure, and explored the associations between metals and their accumulation patterns in bats. The hepatic metal concentrations we recorded were generally consistent with those of similar studies in insectivorous bats. Higher concentrations of Cu and Zn in Cuautitlán and Xochimilco bats were associated with vehicular traffic. Higher concentrations of V, Cr, and Co in Tequixquiac bats and Cd in Tlalcozotitlán bats were linked with industrial, agricultural, or sewage sources. Variations in Fe and Mn concentrations were related to geogenic sources or local conditions. Similar Ni and Pb concentrations were linked with strong homeostatic controls or historical pollution. Accumulation patterns showed that all urban bats belonged to a single population with similar degrees of metal exposure, while rural bats belonged to two different populations exposed to different metals. Our results highlight the need to monitor the emissions generated by particular sources in each study site.

Public Veterinary Medicine: Public Health Rabies virus variants identified in Nuevo Leon State, Mexico, from 2008 to 2015.

To identify rabies virus variants (RVVs) isolated from bats and terrestrial mammals in Nuevo Leon between 2008 and 2015 and Coahuila in 2006. RVVs isolated from 15 bats and terrestrial mammals in Nuevo Leon and from a cow (Bos taurus) in Coahuila, along with 46 reference rabies virus sequences. Antigenic characterization of the 16 isolates was performed with an indirect fluorescent antibody technique. Genomic sequencing of the nucleoprotein gene in the 16 isolates was performed with a reverse transcription PCR assay. Phylogenetic reconstruction of the 62 sequences was performed by means of Bayesian inference. 9 isolates from bats and 1 isolate from a domestic cat that became infected as a result of contact with a Mexican free-tailed bat all clustered in the lineage associated with Lasiurus spp in the Americas or the lineage associated with Tadarida brasiliensis mexicana. An isolate from a domestic dog was identified as a variant associated with the dog-coyote lineage. The RVV isolated from a fox clustered in an Arizona fox lineage. The 3 RVVs from skunks (Mephitis macroura) were placed in a lineage with variants isolated from spotted skunks (Spilogale putorius). The RVV isolated from the cow was clustered in a lineage associated with foxes in Texas and separate from the lineage for the fox from Nuevo Leon. Results reinforced the need for Mexico to implement rabies surveillance and monitoring programs for bats and wild-living terrestrial carnivores.

Functional organization of the primary auditory cortex of the free-tailed bat Tadarida brasiliensis.

The Mexican free-tailed bat, Tadarida brasiliensis, is a fast-flying bat that hunts by biosonar at high altitudes in open space. The auditory periphery and ascending auditory pathways have been described in great detail for this species, but nothing is yet known about its auditory cortex. Here we describe the topographical organization of response properties in the primary auditory cortex (AC) of the Mexican free-tailed bat with emphasis on the sensitivity for FM sweeps and echo-delay tuning. Responses of 716 units to pure tones and of 373 units to FM sweeps and FM-FM pairs were recorded extracellularly using multielectrode arrays in anesthetized bats. A general tonotopy was confirmed with low frequencies represented caudally and high frequencies represented rostrally. Characteristic frequencies (CF) ranged from 15 to 70kHz, and fifty percent of CFs fell between 20 and 30kHz, reflecting a hyper-representation of a bandwidth corresponding to search-phase echolocation pulses. Most units showed a stronger response to downward rather than upward FM sweeps and forty percent of the neurons interspersed throughout AC (150/371) showed echo-delay sensitivity to FM-FM pairs. Overall, the results illustrate that the free-tailed bat auditory cortex is organized similarly to that of other FM-type insectivorous bats.

Richness and activity of arthropodophagous bats in an arid landscape of central México

The insectivorous bats of arid and semi-arid ecosystems have been poorly studied in Mexico. The aim of this work was to determine the richness and activity of insectivorous bats in arid landscapes of central Mexico over an annual cycle and identify the landscape and environmental features related to relative abundance patterns of bats. We carried out captures with mist nets and active acoustic monitoring in 10 transects, semi-active monitoring in eight stations, and passive monitoring in two desert grassland and scrub sites in Aguascalientes and Jalisco, from January to December 2012. The activity index of each insectivorous species was calculated and related to the local features at the landscape level. An automated monitoring weather station was established in the study area to explore the potential effect of environmental conditions on activity through time. Two species of insectivorous bats were captured: Myotis melanorhinus and Myotis occultus; seven additional species belonging to three families were acoustically identified, with Tadarida brasiliensis as the most active species. Activity levels were concentrated during the spring (April-June) and from mid-summer to late fall (August-October). The null activity in winter (January-March) and the increased activity of T. brasiliensis in the spring suggest migratory movements of the species in the region. The highest values of the activity index were recorded in the proximity of water bodies and ravines. Overall activity was recorded at temperatures between 6.8 and 20.3 °C, and under wind speeds between 1.6 and 24.1 km/h.

Monitoring and Characterizing Temporal Patterns of a Large Colony of Tadarida brasiliensis (Chiroptera: Molossidae) in Argentina Using Field Observations and the Weather Radar RMA1

Migratory colonies of up to thousands or millions of Brazilian free-tailed bats (Tadarida brasiliensis) are present in temperate areas of America. The monitoring of these massive colonies is crucial to know their conservation status and to evaluate the important ecosystem services that they provide. The objectives of this study were to characterize and to monitor, with an interdisciplinary approach, one of the largest bat colonies in South America, located in La Calera (Córdoba, Argentina). This study includes eight years of field observations inside of their shelter and outside when the colony emerged. Moreover, these observations were complemented with one year of weather radar detections using the Radar Meteorológico Argentino 1 (RMA1). To determine if a detection is a true or false massive emergence of bats, an algorithm was designed. We observed that this large colony of T. brasiliensis is maternal and migratory, just like others in South and North America. This colony arrives in early spring and births occur two months later, migrations occur in early autumn, meanwhile the shelter is empty or inhabited only by a small group of individuals during the cold seasons. The colony was estimated at 900,000 individuals before births occurred. The radar detection was coincident with field observations, when a simultaneous emergence was observed, as well as in the monitoring throughout the year. This represents the first study made in South America using radar technology for monitoring a bat colony. We here demonstrate that RMA1 is a powerful tool for monitoring this colony in the long term, and even to alert possible changes in permanence in time or in the number of individuals.

The In-Flight Social Calls of Insectivorous Bats: Species Specific Behaviors and Contexts of Social Call Production

Bats could be a useful study system for studying the evolution of social communication, as they exhibit a high diversity of social group size and complexity. However, the study of bat social calls has been limited, as they are nocturnal, volant animals that produce predominately ultrasonic vocalizations. Passive acoustic monitoring studies occasionally capture bat in-flight social calls. The information from surrounding echolocation calls can provide information on species identity, abundance, and foraging activity. I used passive acoustic monitoring in Greensboro, North Carolina, to identify seven types of in-flight social calls from Eptesicus fuscus, Lasiurus borealis, Lasiurus cinereus, Nycticeius humeralis, Perimyotis subflavus, and Tadarida brasiliensis. Eptesicus fuscus, N. humeralis, and T. brasiliensis differed in total social call production, and the proportional use of call types. Shared called types exhibited species-specific signatures. The presence of species-specific signatures indicates bats could potentially discern signaler identity. Social call production was highest early in the night and positively correlated with bat activity. Eptesicus fuscus and T. brasiliensis most commonly produced complex calls, which appear to mediate social interactions between conspecifics while foraging. Nycticeius humeralis most commonly produced downsweeps, which appear to be broad-functioning contact calls. Upsweeps exhibited a similar context to downsweeps, and were commonly produced by E. fuscus and N. humeralis. My results indicate bats use dedicated social calls to mediate different types of social interactions while in flight.

THE STATUS OF PSEUDOGYMNOASCUS DESTRUCTANS IN LOUISIANA

White-nose syndrome (WNS) represents an emerging infectious disease in bats caused by the fungal pathogen Pseudogymnoascus destructans (Pd). The fatal disease has devastated populations of several species of bats in North America, so there is interest in delimiting its current range to aid containment and other management efforts. Early detection of the fungus aids in risk assessment of the disease and managing its presence in areas with hibernating bats. Infection by Pd in bats has been neither surveyed nor reported in Louisiana, despite the fact that WNS has been recorded approximately 150 km across the border of two neighboring states, Arkansas and Mississippi. Between December 2015 and January 2016, we surveyed 190 culverts distributed across the northern portion of Louisiana. In total, we encountered 801 individual bats (355 Perimyotis subflavus, 299 Myotis, 54 Eptesicus fuscus, 47 Tadarida brasiliensis, and 46 Corynorhinus rafinesquii). We used ultraviolet illumination to inspect each individual for presence of WNS symptoms, and no visible symptoms were detected. We also swabbed the skin of 244 bats and 316 habitat walls, and swabs were returned to the laboratory and analyzed using quantitative polymerase chain reaction and Pd-specific primers for presence of the pathogen. No genetic detections occurred in any bat or habitat wall samples. Based on negative detection, we hypothesize that the fungus has not yet been introduced into the state of Louisiana or the environmental conditions of culverts found in Louisiana are not conducive to persistence of the fungus; however, ours is the first survey to assess the status of Pd in the state. Monitoring should continue to confirm that no evidence of the fungal pathogen exists anywhere in the state and to enable rapid response if detection occurs.

Influence of signal direction on sonar interference

How bats mitigate mutual interference is a long-standing question that has ecological and technological implications as biosonar systems continue to outperform artificial sonar systems in noisy, cluttered environments. Echolocating bats display a mutual suppression response, slowing their pulse emission rates when flying in groups to gain a net improvement in sonar performance. However, flight paths, directional effects, plus contextual and attentional processes influence the levels of mutual interference, causing some noises to be more deleterious than others. To tease apart the impact of these factors, we used playback experiments with flying Mexican free-tailed bats, Tadarida brasiliensis , to test whether the relative directional orientation of an interfering signal versus its returning echoes had a greater impact on a bat's sonar performance. We tested two competing hypotheses: (1) the intensity hypothesis predicts that a signal that is emitted towards a signalling bat is louder and will mask returning echoes more than a signal that is emitted in the same direction as a bat's emitted signal; (2) the similarity hypothesis predicts that a signal that is emitted in the same direction as a bat's signal will create echoes similar in amplitude and timing to those of the signalling bat's own echoes , which should cause greater interference than a loud, less similar signal. We analysed emission rates of bats navigating in both open and cluttered spaces while we varied the directional orientation of an artificial stimulus relative to the bat's flight trajectory. Both emission rates and navigational performance decreased significantly when playback was directed in the same heading as the flying bat, indicating that competing echo wave-fronts are more disruptive to a flying bat than the much louder source signal that produced them. This observation is important because it potentially reveals the impact of attentional processes on sonar performance. This study provides new information on how echolocating bats experience interference and the behavioural strategies they use to overcome jamming. • Bat biosonar is directionally sensitive to the source of acoustic interference. • Pulses arriving from behind bats had the greatest impact on biosonar performance. • Low-intensity echo streams may be more distracting than the louder source signal. • The results have important implications for how bats space themselves in groups.

Winter habitats of bats in Texas.

Few studies have described winter microclimate selection by bats in the southern United States. This is of particular importance as the cold-adapted fungus, Pseudogymnoascus destructans, which causes the fatal bat disease white-nose syndrome (WNS), continues to spread into southern United States. To better understand the suitability of winter bat habitats for the growth of P. destructans in this region, we collected roost temperature and vapor pressure deficit from 97 hibernacula in six ecoregions in Texas during winter 2016-17 and 2017-18. We also measured skin temperature of Rafinesque's big-eared bats (Corynorhinus townsendii), Townsend's big-eared bats (C. townsendii), big-brown bats (Eptesicus fuscus), southeastern myotis (Myotis austroriparius), cave myotis (M. velifer), tri-colored bats (Perimyotis subflavus), and Mexican free-tailed bats (Tadarida brasiliensis) during hibernation to study their use of torpor in these habitats. We found that temperatures within hibernacula were strongly correlated with external air temperatures and were often within the optimal range of temperatures for P. destructans growth. Hibernacula and skin temperatures differed among species, with Rafinesque's big-eared bats, southeastern myotis, and Mexican free-tailed bats occupying warmer microclimates and having higher torpid skin temperatures. For species that were broadly distributed throughout Texas, hibernacula and skin temperatures differed within species by ecoregion; Tri-colored bats and cave myotis in colder, northern regions occupied colder microclimates within hibernacula and exhibited colder skin temperatures, than individuals of the same species in warmer, southern regions. These data illustrate the variability in microclimates used as hibernacula by bats in Texas and suggest similar variation in susceptibility to WNS in the state. Thus, monitoring microclimates at winter roosts may help predict where WNS may develop, and where management efforts would be most effective.

Seasonal Dynamics of Lipid Metabolism and Energy Storage in the Brazilian Free-Tailed Bat

As small, flying, mammalian endotherms, insectivorous bats are adapted to operate at high levels of energy expenditure. In response to seasonally variable challenges, we predicted that bats should balance energy budgets by flexibly adjusting aspects of their physiology or behavior in ways that elevate metabolic capacity. We examined variation in energy storage and pathways for oxidative metabolism in Brazilian free-tailed bats (Tadarida brasiliensis) related to estimated costs associated with reproduction and migration. We collected pectoral muscle and liver from female T. brasiliensis at six time points during the summer and fall and measured changes in the activity of four enzymes involved with lipid metabolism. Body mass varied substantially with life-cycle stage, suggesting that rapid accumulation and use of fat stores occurs in response to current and anticipated energy demands. Catabolic enzyme activity (carnitine palmitoyl transferase [CPT], 3-hydroxyacyl-CoA dehydrogenase [HOAD], and citrate synthase [CS]) in the muscle was increased during lactation compared with early pregnancy but exhibited no change before fall migration. While there was no temporal change in lipid biosynthetic capacity in the liver, fatty acid synthase activity was negatively correlated with body mass. Variation in body mass and enzyme activity in T. brasiliensis during the summer suggests that stored energy is mobilized and lipid oxidative capacity is increased during periods of increased demand and that lipid biosynthetic capacity is increased with depletion of fat stores. These results suggest that bats are able to flexibly adjust metabolic capacity based on energy requirement to maintain energy balance despite high levels of expenditure.

Migration and reproduction are associated with similar degrees of phenotypic flexibility in an insectivorous bat.

As organisms face variation in energetic challenges and physiological demands, they often respond with reversible changes in behavior, physiology, and morphology, described as phenotypic flexibility. From the magnitude of phenotypic change, we can infer the energetic challenges of different life stages. We studied phenotypic flexibility in a population of reproductive and pre-migratory female insectivorous bats (Tadarida brasiliensis). While female reproductive demands are well described in insectivorous bats, there are questions regarding the demands of migration. Our objective was to measure phenotypic flexibility to assess the cost of autumn migration compared to reproduction in an insectivorous bat. We measured plasma triglycerides to quantify foraging rate, and body composition (body mass and individual organ mass) of T. brasiliensis throughout the summer season (from arrival in spring through pre-migration/migration departure in autumn) according to the female reproductive cycle. We found phenotypic changes during pre-migration/migration similar to periods of high-energy demand during reproduction (e.g., late pregnancy and lactation). Most notably, bats weighed as much during peak pregnancy, as they did during migration, and the rapid mass gain from post-lactation through the migratory period was due to a combination of hyperphagia and hypertrophy of digestive organs. Our results indicate that energetic demands incurred during migration are similar to those during reproduction and emphasize the energetic challenges of migration.

Canopy Cover Shapes Bat Diversity across an Urban and Agricultural Landscape Mosaic

SummaryHuman alteration of the planet’s terrestrial landscapes for agriculture, habitation and commerce is reshaping wildlife communities. The threat of land cover change to wildlife is pronounced in regions with rapidly growing human populations. We investigated how species richness and species-specific occurrence of bats changed as a function of land cover and canopy (tree) cover across a rapidly changing region of Florida, USA. Contrary to our predictions, we found negligible effects of agriculture and urban development on the occurrence of all species. In contrast, we found that a remotely sensed metric of canopy cover on a broad scale (25 km2) was a good predictor of the occurrence of eight out of ten species. The occurrence of all smaller bats (vespertilionids) in our study increased with 0–50% increases in canopy cover, while larger bats showed different patterns. Occurrence of Brazilian free-tailed bats (Tadarida brasiliensis) decreased with increasing canopy cover, and Florida bonneted bats (Eumops floridanus) were not influenced by canopy cover. We conclude that remotely sensed measures of canopy cover can provide a more reliable predictor of bat species richness than land-cover types, and efforts to prevent the loss of bat diversity should consider maintaining canopy cover across mosaic landscapes with diverse land-cover types.