Tadarida Brasiliensis Research Articles

Patterns of Bat Distribution and Foraging Activity in a Highly Urbanized Temperate Environment.

Understanding how to manage biodiversity in urban areas will become increasingly important as density of humans residing in urban centers increases and urban areas expand. While considerable research has documented the shifts in biodiversity along urbanization gradients, much less work has focused on how characteristics of dense urban centers, effectively novel environments, influence behavior and biodiversity. Urban bats in San Francisco provide an opportunity to document changes in behavior and biodiversity to very high-density development. We studied (1) the distribution and abundance of bat foraging activity in natural areas; and (2) characteristics of natural areas that influence the observed patterns of distribution and foraging activity. We conducted acoustic surveys of twenty-two parks during 2008–2009. We confirmed the presence of four species of bats (Tadarida brasiliensis, Myotis yumanensis, Lasiurus blossevillii, and M. lucifugus). T. brasiliensis were found in all parks, while M. yumanensis occurred in 36% of parks. Results indicate that proximity to water, park size, and amount of forest edge best explained overall foraging activity. Proximity to water best explained species richness. M. yumanensis activity was best explained by reduced proportion of native vegetation as well as proximity to water. Activity was year round but diminished in December. We show that although bats are present even in very densely populated urban centers, there is a large reduction in species richness compared to that of outlying areas, and that most habitat factors explaining their community composition and activity patterns are similar to those documented in less urbanized environments.

Florida's Bats: Brazilian Free-tailed Bat

The Brazilian free-tailed bat lives throughout Florida and is the state’s most common bat. They are important economically because they consume large quantities of insect pests. This 3-page fact sheet explains how to differentiate Brazilian free-tailed bats from velvety free-tailed bats and Florida bonneted bats. Written by Holly K. Ober, Terry Doonan, and Emily Evans, and published by the UF Department of Wildlife Ecology and Conservation, November 2016. WEC379/UW424: Florida's Bats: Brazilian Free-tailed Bat (ufl.edu)

Florida's Bats: Florida Bonneted Bat

The Florida bonneted bat is one of only two endangered species of bat in Florida and the state’s only endemic flying mammal (“endemic” means that it is found nowhere in the world but in Florida). With a 20-inch wingspan, it is Florida’s largest bat and the third largest of all 48 species of bats in the United States. The Florida bonneted bat was listed as federally endangered in 2013 because of concerns over habitat loss, degradation, and modification caused by humans. Additional concerns include the species’ small population size and restricted range, the small number of known colonies, their slow reproduction, and the relative isolation of separate populations of bonneted bats. This 3-page fact sheet explains how to differentiate Florida bonneted bats from velvety free-tailed bats and Brazilian free-tailed bats and explains what to do if you find one of these endangered bats. Written by Holly K. Ober, Terry Doonan, and Emily Evans, and published by the UF Department of Wildlife Ecology and Conservation, October 2016. WEC381/UW426: Florida's Bats: Florida Bonneted Bat (ufl.edu)

Florida's Bats: Velvety Free-Tailed Bat

The velvety free-tailed bat is found nowhere in the United States but extreme south Florida. These bats emerge from their roosts earlier than most other bats, often shortly before sunset. This 2-page fact sheet explains how to differentiate velvety free-tailed bats from Brazilian free-tailed bats and Florida bonneted bats. Written by Holly K. Ober, Terry Doonan, and Emily Evans, and published by the UF Department of Wildlife Ecology and Conservation, November 2016. WEC380/UW425: Florida's Bats: Velvety Free-Tailed Bat (ufl.edu)

Airplane tracking documents the fastest flight speeds recorded for bats.

The performance capabilities of flying animals reflect the interplay of biomechanical and physiological constraints and evolutionary innovation. Of the two extant groups of vertebrates that are capable of powered flight, birds are thought to fly more efficiently and faster than bats. However, fast-flying bat species that are adapted for flight in open airspace are similar in wing shape and appear to be similar in flight dynamics to fast-flying birds that exploit the same aerial niche. Here, we investigate flight behaviour in seven free-flying Brazilian free-tailed bats (Tadarida brasiliensis) and report that the maximum ground speeds achieved exceed speeds previously documented for any bat. Regional wind modelling indicates that bats adjusted flight speeds in response to winds by flying more slowly as wind support increased and flying faster when confronted with crosswinds, as demonstrated for insects, birds and other bats. Increased frequency of pauses in wing beats at faster speeds suggests that flap-gliding assists the bats' rapid flight. Our results suggest that flight performance in bats has been underappreciated and that functional differences in the flight abilities of birds and bats require re-evaluation.

Improving spatio-temporal benefit transfers for pest control by generalist predators in cotton in the southwestern US

ABSTRACTGiven rapid changes in agricultural practice, it is critical to understand how alterations in ecological, technological, and economic conditions over time and space impact ecosystem services in agroecosystems. Here, we present a benefit transfer approach to quantify cotton pest-control services provided by a generalist predator, the Mexican free-tailed bat (Tadarida brasiliensis mexicana), in the southwestern United States. We show that pest-control estimates derived using (1) a compound spatial–temporal model – which incorporates spatial and temporal variability in crop pest-control service values – are likely to exhibit less error than those derived using (2) a simple-spatial model (i.e., a model that extrapolates values derived for one area directly, without adjustment, to other areas) or (3) a simple-temporal model (i.e., a model that extrapolates data from a few points in time over longer time periods). Using our compound spatial–temporal approach, the annualized pest-control value was $12.2 million, in contrast to an estimate of $70.1 million (5.7 times greater), obtained from the simple-spatial approach. Using estimates from one year (simple-temporal approach) revealed large value differences (0.4 times smaller to 2 times greater). Finally, we present a detailed protocol for valuing pest-control services, which can be used to develop robust pest-control transfer functions for generalist predators in agroecosystems.EDITED BY Neville Crossman

Electromagnetic Model Reliably Predicts Radar Scattering Characteristics of Airborne Organisms.

The radar scattering characteristics of aerial animals are typically obtained from controlled laboratory measurements of a freshly harvested specimen. These measurements are tedious to perform, difficult to replicate, and typically yield only a small subset of the full azimuthal, elevational, and polarimetric radio scattering data. As an alternative, biological applications of radar often assume that the radar cross sections of flying animals are isotropic, since sophisticated computer models are required to estimate the 3D scattering properties of objects having complex shapes. Using the method of moments implemented in the WIPL-D software package, we show for the first time that such electromagnetic modeling techniques (typically applied to man-made objects) can accurately predict organismal radio scattering characteristics from an anatomical model: here the Brazilian free-tailed bat (Tadarida brasiliensis). The simulated scattering properties of the bat agree with controlled measurements and radar observations made during a field study of bats in flight. This numerical technique can produce the full angular set of quantitative polarimetric scattering characteristics, while eliminating many practical difficulties associated with physical measurements. Such a modeling framework can be applied for bird, bat, and insect species, and will help drive a shift in radar biology from a largely qualitative and phenomenological science toward quantitative estimation of animal densities and taxonomic identification.

Signal characteristics and echolocation challenges of Mexican free-tailed bats during high-speed flight

Female Mexican free-tailed bats (Tadarida brasiliensis) form large maternal colonies numbering up to several million. After their nightly emergence and feeding, they return to the roost from high elevations and speeds nearing 100 km/h. At these speeds, the bats should experience, among other things, difficulties in object distance encoding due to the large distance travelled before echo returns and significant Doppler shifts to their echoes. Further, they face navigational challenges from nearby conspecifics. In this study, we characterized the acoustics of returning Mexican free-tailed bats and investigated for possible Doppler shift compensation during various flight speeds. Synchronized acoustic and thermal imagery recordings were conducted at several caves across multiple mornings during cave re-entry. Call sequences for individual bats were extracted for different flight speeds, and changes in call parameters were compared within each call sequence. First basic analysis indicates a possible lack of D...

Variation in frequency-modulated call type for different flight densities in Mexican Free-tailed bats

Mexican free-tailed bats (Tadarida brasiliensis) adapt their call type depending on multiple factors. These bats have two general types of echolocation sounds, frequency-modulated (FM) and constant frequency (CF). CF calls are generally produced during the search phase of foraging, and FM calls are used during approach, prey capture, and roost emergence. In this study, we examined how Mexican free-tailed bats adapt their calls during emergence to avoid echo interference. We extracted individual calls from within a 500-ms sample that corresponded to five different emergence density categories. We found that these bats produce eight different FM call types during emergence. For each call within the sample, we characterized the call shape and calculated different parameters (duration, start frequency, peak frequency, end frequency). We compared the acoustic parameters across density categories and call shape, and compared the distribution of call shape across density categories. The results indicate that the call parameters and call shape vary from bat to bat, but there is no clear trend that this variance is due to the bat density. Therefore, these bats are likely changing their call shape and frequency characteristics to distinguish their own echoes from those of other bats.

Emergence density and stream frequency spectra of Tadarida brasiliensis

Bats depend on echolocation to maneuver through their environment. Mexican Free-Tailed bats (Tadarida brasiliensis) form large maternal colony roosts and emerge in large, dense groups. Previous work found that the T. brasilensis bats adjust their call structure during emergence, which may help the bats avoid flight collisions. The limited physical space between bats in the emerging stream is not only problematic with flight collisions, but also with echolocation interference. In this study, we tested how the density of emergence affects echolocation. Specifically, we tested the hypothesis that the density of flying bats affects echolocation characteristics of the entire stream. We determined six emergence density categories from thermal imagery, and randomly selected 20, 500 ms audio samples corresponding to each density. For each audio sample, we calculated the frequency spectrum, and analyzed how the stream frequency spectrum changed according to population density. Across densities, the stream frequency spectra all have the same shape and peak frequencies, but the variance for certain frequencies differs. This change in variance suggests that these bats are attempting to avoid jamming in dense emerging streams by altering their frequencies from bat-to-bat, irrespective of density.

Specialized facial muscles support sonar beam-forming by free-tailed bats

Echolocating bats may be able to manipulate the acoustic projection pattern of their sonar pulse emissions, but the mechanism(s) for this and potential constraints are unexplored. The Mexican free-tailed bat (Tadarida brasiliensis) appears to achieve this by finely adjusting the shape of its mouth cavity (beam-forming) in a behavior akin to supralaryngeal speech motor control by humans. Flying Tadarida raise their nose and lips preceding each echolocation pulse with a hypertrophied set of specialized facial muscles (levator labii complex). We investigated 1) muscle complex activity patterns during sonar performance, 2) whether the muscles tissue displayed necessary fast-twitch specializations to accommodate echolocation, and 3) how manipulations of mouth shape altered 3D beam patterns. First, EMG recordings from awake echolocating bats confirmed the muscles were activated in precise temporal coordination with pulse emissions. Second, we describe the anatomical connectivity of the muscle complex, origin an...

Infectivity of attenuated poxvirus vaccine vectors and immunogenicity of a raccoonpox vectored rabies vaccine in the Brazilian Free-tailed bat (Tadarida brasiliensis)

Bats (Order Chiroptera) are an abundant group of mammals with tremendous ecological value as insectivores and plant dispersers, but their role as reservoirs of zoonotic diseases has received more attention in the last decade. With the goal of managing disease in free-ranging bats, we tested modified vaccinia Ankara (MVA) and raccoon poxvirus (RCN) as potential vaccine vectors in the Brazilian Free-tailed bat (Tadarida brasiliensis), using biophotonic in vivo imaging and immunogenicity studies. Animals were administered recombinant poxviral vectors expressing the luciferase gene (MVA-luc, RCN-luc) through oronasal (ON) or intramuscular (IM) routes and subsequently monitored for bioluminescent signal indicative of viral infection. No clinical illness was noted after exposure to any of the vectors, and limited luciferase expression was observed. Higher and longer levels of expression were observed with the RCN-luc construct. When given IM, luciferase expression was limited to the site of injection, while ON exposure led to initial expression in the oral cavity, often followed by secondary replication at another location, likely the gastric mucosa or gastric associated lymphatic tissue. Viral DNA was detected in oral swabs up to 7 and 9 days post infection (dpi) for MVA and RCN, respectively. While no live virus was detected in oral swabs from MVA-infected bats, titers up to 3.88 x 104 PFU/ml were recovered from oral swabs of RCN-infected bats. Viral DNA was also detected in fecal samples from two bats inoculated IM with RCN, but no live virus was recovered. Finally, we examined the immunogenicity of a RCN based rabies vaccine (RCN-G) following ON administration. Significant rabies neutralizing antibody titers were detected in the serum of immunized bats using the rapid fluorescence focus inhibition test (RFFIT). These studies highlight the safety and immunogenicity of attenuated poxviruses and their potential use as vaccine vectors in bats.

Generation and Characterization of Eptesicus fuscus (Big brown bat) kidney cell lines immortalized using the Myotis polyomavirus large T-antigen

It is speculated that bats are important reservoir hosts for numerous viruses, with 27 viral families reportedly detected in bats. Majority of these viruses have not been isolated and there is little information regarding their biology in bats. Establishing a well-characterized bat cell line supporting the replication of bat-borne viruses would facilitate the analysis of virus-host interactions in an in vitro model. Currently, few bat cell lines have been developed and only Tb1-Lu, derived from Tadarida brasiliensis is commercially available. Here we describe a method to establish and immortalize big brown bat (Eptesicus fuscus) kidney (Efk3) cells using the Myotis polyomavirus T-antigen. Subclones of this cell line expressed both epithelial and fibroblast markers to varying extents. Cell clones expressed interferon beta in response to poly(I:C) stimulation and supported the replication of four different viruses, namely, vesicular stomatitis virus (VSV), porcine epidemic diarrhea coronavirus (PED-CoV), Middle-East respiratory syndrome coronavirus (MERS-CoV) and herpes simplex virus (HSV). To our knowledge, this is the first bat cell line from a northern latitude insectivorous bat developed using a novel technology. The cell line has the potential to be used for isolation of bat viruses and for studying virus-bat interactions in culture.

The Secret Lives of Bats: My Adventures with the World’s Most Misunderstood Mammals

Tuttle, M. D. 2015. The Secret Lives of Bats: My Adventures with the World’s Most Misunderstood Mammals. Houghton Mifflin Harcourt, Boston, Massachusetts and New York, 271 pp. (hard cover). ISBN 978-0-544-38227-5, $26. If bats could choose one human advocate, I am quite sure it would be Merlin Tuttle—an ecologist, conservationist, and wildlife photographer with a lifelong passion for bats and more than 50 years dedicated to their research and preservation. His new book— The Secret Lives of Bats: My Adventures with the World’s Most Misunderstood Mammals —delivers on the title’s promise. Tuttle delights us with some fascinating facets of bat biology and natural history, along with tales of hard work, science, stories of almost fatal adventures on different continents, battles to save species that otherwise would now be extinct or on the brink of extinction principally due to fear and misunderstanding, and friendship with moonshiners and poachers. Most of this is summarized in the preface, which introduces the emblematic example of Austin, Texas, the city that now proudly calls itself the bat capital of America. In 1984, 1.5 million free-tailed bats ( Tadarida brasiliensis ) had settled in the crevices of the Congress Avenue Bridge, and Austinites reacted in fear and panic, clamoring for their extermination. Aware of the situation, Tuttle resigned his job as curator of mammals at the Milwaukee Public Museum, Wisconsin, and moved to Austin with his recently founded Bat Conservation International (BCI). After his strong intervention emphasizing the truth about bats to policy makers and the public in general, fear and panic turned into respect and appreciation. Nowadays, the free-tailed bat colony is the largest urban colony in the world, consumes about 15 tons of insects each night, and brings in US … Fiocruz Mata Atlântica, Fundacao Oswaldo Cruz, Rio de Janeiro, CEP 22713-375, Brazil; e-mail: rmoratelli{at}fiocruz.br.

Broad and Temperature Independent Replication Potential of Filoviruses on Cells Derived From Old and New World Bat Species.

Filoviruses are strongly associated with several species of bats as their natural reservoirs. In this study, we determined the replication potential of all filovirus species: Marburg marburgvirus, Taï Forest ebolavirus, Reston ebolavirus, Sudan ebolavirus, Zaire ebolavirus, and Bundibugyo ebolavirus. Filovirus replication was supported by all cell lines derived from 6 Old and New World bat species: the hammer-headed fruit bat, Buettikofer's epauletted fruit bat, the Egyptian fruit bat, the Jamaican fruit bat, the Mexican free-tailed bat and the big brown bat. In addition, we showed that Marburg virus Angola and Ebola virus Makona-WPGC07 efficiently replicated at 37°C, 37°-41°C, or 41°C, contrary to the hypothesis that temporal elevation in temperature due to flight affects filovirus replication in bats.

Roving with a Digital Visual Library: Increased Learning Opportunities at Carlsbad Caverns National Park

At Carlsbad Caverns National Park, park rangers blended traditional personal interpretation with technology to showcase park-based research and to advance science literacy among visitors. Interpreters and Scientists Working on Our Parks (iSWOOP) provided interpreters with professional development and a selection of visualizations from scientists’ research on Brazilian free-tailed bats and their habitat at Carlsbad Caverns. After using tablets containing these visualizations for informal interpretive interactions, the interpreters responded to an open-ended survey. The authors examined interpreters’ responses, finding that interpreters regarded tablets as helpful in accomplishing several interpretive goals, especially in particular locations. Interpreters were strategic in initiating and sustaining interactions. Visitors’ reactions were positive; nevertheless, there were challenges indicating that this new form of interpretation is worthy of further research.

Habitat diversity promotes bat activity in a vineyard landscape

Intensification of agricultural production has greatly limited the capacity of agricultural land to support other species. Maintaining landscape heterogeneity in and around agricultural landscapes can help conserve biodiversity and potentially natural pest control. Whereas bats (order: Chiroptera) are highly valued as natural predators of agricultural pests, little is known about the distribution and abundance of bat species across different types of agricultural landscapes. The objective of our study was to assess how local remnant habitat and surrounding natural areas influence bat activity levels within a vineyard landscape. To accomplish this, we conducted acoustic surveys at 21 vineyards within the North Coast wine-grape growing region of California. Using generalized linear mixed-models, we assessed the influence of local remnant habitat and surrounding natural areas to predict overall and species-specific activity patterns. A total of 14,613 bat passes were recorded, of which 80% were identified by a random forest classifier as either Tadarida brasiliensis the Brazilian free-tailed bat (25%), Myotis yumanensis the Yuma Myotis (24%), or Eptesicus fuscus the big brown bat (23%). The results of our models indicate that total bat activity, and the activity of each of the common bat species, was higher adjacent to remnant vegetation along the edges of vineyards as compared to within the vineyard, but that the effect of landscape-scale characteristics on bat activity was weak. This suggests that natural trees and shrubs should be conserved and restored throughout the vineyard landscape to enhance bat abundance for a win-win agricultural production and conservation solution.

Estimating colony sizes of emerging bats using acoustic recordings.

The decline of bats demands more widespread monitoring of populations for conservation and management. Current censusing methods are either prone to bias or require costly equipment. Here, we report a new method using passive acoustics to determine bat count census from overall acoustic amplitude of the emerging bat stream. We recorded the video and audio of an emerging colony of Mexican free-tailed bats from two cave locations across multiple nights. Instantaneous bat counts were calculated from the video frames, and the bat stream’s acoustic amplitude corresponding to each video frame was determined using three different methods for calculating acoustic intensity. We found a significant link between all three acoustic parameters and bat count, with the highest R2 of 0.742 linking RMS pressure and bat count. Additionally, the relationship between acoustics and population size at one cave location could accurately predict the population size at another cave location. The data were gathered with low-cost, easy-to-operate equipment, and the data analysis can be easily accomplished using automated scripts or with open-source acoustic software. These results are a potential first step towards creating an acoustic model to estimate bat population at large cave colonies worldwide.

Selection of Building Roosts by Mexican Free-Tailed Bats (Tadarida brasiliensis) in an Urban Area

The Mexican free-tailed bat (Tadarida brasiliensis) is one of the most widely distributed bat species in the Western Hemisphere. Despite their prevalence in urban environments, limited research has been conducted to determine the features of buildings or of the surroundings that might affect the likelihood of a building being selected by Mexican free-tailed bats as a roost. Our study objectives were to improve the current understanding of Mexican free-tailed bat's urban roosting preferences with regard to both microhabitat and macrohabitat. Between August 2010 and August 2012, we conducted acoustic surveys and emergence observations and examined 218 buildings in Waco, TX, USA. A total of 54 day-roosts for Mexican free-tailed bats was identified. At the microhabitat scale, modeling of building characteristics and opening characteristics showed that bats preferred to roost in tall and abandoned buildings. Roost exits were more likely the results of structural damage to buildings and less likely to have vege...

Impact of Wind Facilities on Bats in the Neotropics

We monitored the bat fatalities caused by a 13 turbines wind facility installed in western Puerto Rico (West Indies) over a period of 23 months. The post-construction monitoring includes observed fatalities and a corrected fatality estimate expressed as bats/ turbine/year adjusted for bat carcass removal rates, searcher efficiency, and percent area searched. Data on seasonality of fatalities and distance of carcasses from turbines is also provided. Eleven out of the 13 species of bats in Puerto Rico suffered fatalities, including all five species of phyllostomids. These were: Molossus molossus and Tadarida brasiliensis (Molossidae); Artibeus jamaicensis, Monophyllus redmani, Stenoderma rufum, Brachyphylla cavernarum and Erophylla bombifrons (Phyllostomidae); Noctilio leporinus (Noctilionidae); Eptesicus fuscus and Lasiurus minor (Vespertilionidae); and Mormoops blainvillei (Mormoopidae). This is one of the first published reports of the impact of wind turbines on bats in the Neotropics.