Tadarida Brasiliensis Research Articles

Brazilian free-tailed bats (Tadarida brasiliensis: Molossidae, Chiroptera) at high altitude: links to migratory insect populations

Existing information on the activity of bats in the aerosphere is restricted almost exclusively to altitudes that are within a few tens of meters above the ground. We report a total of 50.2 h of ultrasonic recordings made using radio microphonic bat detectors suspended from free-floating helium balloons and from kites. The data include a total of 22 353 echolocative calls from ground-level to 1118 m above ground level (AGL). These calls are attributed to Brazilian free-tailed bats based on acoustic features and the large numbers and high-altitude aerial dispersion of these bats over the local landscape. Bat activity varied significantly throughout the air column and was greatest at 400-500 m AGL and near ground level. Feeding buzzes, indicating feeding on aerial prey, were most abundant near ground level and at 400-500 m, and were detected to altitudes of ∼ 900 m AGL. The peak activity of bats at 400-500 m AGL is concordant with the altitude of the atmospheric boundary layer and the seasonal formation of the low-elevation southerly wind jet that has been identified as a major aeroecological corridor for the nocturnal dispersal of noctuid moths and other insects.

Observations and Larval Descriptions of Fleas (Siphonaptera: Ceratophyllidae, Ctenophthalmidae, Ishnopsyllidae) of the Southern Flying Squirrel, Little Brown Bat, and Brazilian Free-Tailed Bat (Mammalia: Rodentia, Chiroptera)

Larvae of the four fleas infesting nests of the southern flying squirrel, Glaucomys volans colans (L.) [Conorhinopsylla stanfordi Stewart, Epitedia faceta (Rothschild), Opisodasys pseudarctomys (Baker), and Orchopeas howardi (Baker)], and of the bat fleas Myodopsylla insignis (Rothschild) and Sternopsylla distincta texana (C. Fox), associated with the bats Myotis lcifuigus (Le Conte) and Tadarida brasiliensis (I. Geof. St. Hilaire), respectively, are described. C. stanfordi has the second posterior-row seta on abdominal segments 1-5 at most one fourth the length of the first and third setae, but it is unique among the Leptopsyllini with five short setae in abdominal segment 9 anterior row. E. faceta has the straight line of anterior-row setae 2-5 on abdominal segment 1, which is diagnostic for Phalacropsyllini. O. howardi and O. pseudarctomys have three anterior-row setae on the anal comb, three ventrolateral setae on the anal segment (abdominal segment 10), and a narrow mandible with five or more teeth as other Ceratopyllinae, but O. pseudarctomys is distinguishable from O. howardi because the first setae on the posterior row of the head is long (greater than one half the length of the third posterior-row setae), the ventral setae on abdominal segment 7 are different sizes, and the third anterior-row setae on abdominal segment 8 does not extend past the spiracle posterior to it. Bat flea larvae have six posterior-row setae on abdominal segments 1-9 with the anal comb anterior row with two or more setae; M. insignis has eight mandible teeth and S. distincta texana three to four.

Morcegos (Mammalia, Chiroptera) na região de Ponta Grossa, Campos Gerais, Paraná, Brasil

The diet, reproduction and activity time of bat species found in Ponta Grossa county, Campos Gerais region, were studied. Collections were conducted in four forest fragments, during 272 hours, on 48 m 2 of nets and roosting sites; the total capture effort was 1.52.10 3 h.m 2 . Eight species (247 individuals) were registered: Artibeus lituratus (Olfers, 1818), Sturnira lilium (E. Geoffroy, 1810), Desmodus rotundus (E. Geoffroy, 1810) (Phyllostomidae); Tadarida brasiliensis (Desmarest, 1819), Eumops auripendulus (Shaw, 1800) (Molossidae); Eptesicus brasiliensis (Shaw, 1800), Myotis nigricans (Schinz, 1821), and Histiotus velatus (I. Geoffroy, 1824) (Vespertilionidae). The Phyllostomidae family was the most frequently captured. Solanaceae, Moraceae, Piperaceae, and Rosaceae were found in the diet of frugivores; six orders of insects and the class Arachnida were found in the diets of insectivores. Pregnant females were found in September and October and lactating ones in November and December. The collection peak was reached in the second hour-and-a-half. Preservation of the regional forested and altered areas is required for survival of the local chiropterofauna.

Molecular epidemiology of rabies in Colombia 1994–2005 based on partial nucleoprotein gene sequences

One hundred and twenty-four rabies viruses (RABV) were isolated from humans and eight species of mammals in Colombia during 1994–2005. To determine the genetic and reservoir-associated diversity cDNA fragments encoding 88 amino acids at the carboxyl terminus of the nucleoprotein were sequenced and used in phylogenetic analyses. Eight genetic lineages (GL) were characterized. GL1, GL2 and GL3 consisted of dog-associated antigenic variant (AV) 1 RABV, isolated in the centre-east, north and southwest of Colombia, respectively. GL1 is apparently extinct in Colombia. The GL4 were AV3, AV8 and non-determined (ND) AV viruses associated with hematophagous bats. The GL5 and GL6 consisted of AV4 viruses. GL6 isolate was found associated with Tadarida brasiliensis bats. GL5 segregated independently. The GL7 and GL8 segregated independently within clades associated with colonial insectivorous and solitary bats, respectively. Both of these were represented by NDAV viruses. Viruses isolated from humans grouped within GL2, GL3 and GL4, which in turn corresponded to AV1, 3, 8 and ND. Dogs and D. rotundus are the two major rabies reservoirs and vectors in Colombia. Insectivorous bats may also be important rabies reservoirs but spillovers to other species are rare. Our data were consistent with previous studies in which partial Psi, G and L gene sequences were analyzed. Our results confirmed the existence of RABV of unclassified AV in Colombia.

Variability in the echolocation of Tadarida brasiliensis: effects of geography and local acoustic environment

We examined variation in the echolocation calls of Brazilian free-tailed bats, Tadarida brasiliensis, on a broad geographical scale and in response to local environmental variables. Significant differences in call structure were observed among populations throughout the species range in the United States, but this variation was not associated with geographical distance or local weather conditions. Observed variability between sites was primarily due to differences between bats, and the flexibility in call structure that can be achieved by individuals. During this study, we observed that bats recorded in the presence of high-frequency sounds from chorusing insects used higher call frequencies than bats recorded in silence. This led us to test the hypothesis that bats adjust echolocation call structure in response to local ambient noise. We broadcast experimentally manipulated ultrasonic insect sounds to free-flying Brazilian free-tailed bats and found a positive correlation between the frequency of the insect sound stimulus and the call frequencies used by bats. These results document that bats adjust echolocation call structure to avoid acoustic interference from ambient noise in their local environment.

SEASONALITY AND FIDELITY IN ROOST USE OF THE MEXICAN FREE-TAILED BAT, TADARIDA BRASILIENSIS, IN AN URBAN SETTING

We studied 7 urban roosts occupied by Mexican free-tailed bats (Tadarida brasiliensis) in downtown Waco, Texas, from August 2001 to September 2002. We examined frequency of roost use, colony sizes, and roost fidelity in relation to gender. Use of roosts and colony sizes were highest in the fall and lowest in the winter, but fluctuated widely during the study. These roosts were not used by maternity colonies, and patterns of occupancy suggested that they served as stopover sites during migratory seasons. Individual bats exhibited high fidelity to discrete roosts included in the study. However, the bats commonly left the study area, suggesting that populations are defined at greater spatial scales than we included in this study. Male bats were recaptured more often and spent more days in the study area than female bats, suggesting a sexual difference in roosting behavior.

Eavesdropping by bats on the feeding buzzes of conspecifics

Echolocation calls of most bats are emitted at high intensities and subject to eavesdropping by nearby conspecifics. Bats may be especially attentive to “feeding buzz” calls, which are emitted immediately before attack on airborne insects and indicate the potential presence of prey in the nearby area. Although previous work has shown that some species are attracted to feeding buzzes, these studies did not provide a well-controlled test of eavesdropping, as comparisons were made between responses to natural and altered signals (e.g., forward versus backward broadcasts of calls). In this study, I assessed the importance of feeding buzzes by conducting playbacks of controlled echolocation stimuli. I presented free-flying Brazilian free-tailed bats, Tadarida brasiliensis (I. Geoffroy, 1824), with echolocation call sequences in which feeding buzz calls were either present or absent, as well as a silence control. I determined levels of bat activity by counting the number of echolocation calls and bat passes recorded in the presence of each stimulus, and found significantly greater bat activity in response to broadcasts that contained feeding buzzes than to broadcasts without feeding buzzes or to the silence control. These results indicate that bats are especially attentive to conspecific feeding buzz calls and that eavesdropping may allow a bat to more readily locate rich patches of insect prey.

Low rates of hydrogen peroxide production by isolated heart mitochondria associate with long maximum lifespan in vertebrate homeotherms

An inverse correlation between free radical production by isolated mitochondria and longevity in homeotherms has been reported, but previous comparative studies ignored possible confounding effects of body mass and phylogeny. We investigated this correlation by comparing rates of hydrogen peroxide (H(2)O(2)) production by heart mitochondria isolated from groups or pairs of species selected to have very different maximum lifespans but similar body masses (small mammals, medium-sized mammals, birds). During succinate oxidation, H(2)O(2) production rates were generally lower in the longer-lived species; the differences arose at complex I of the electron transport chain during reverse electron transport. Additional data were obtained from large species and the final dataset comprised mouse, rat, white-footed mouse, naked mole-rat, Damara mole-rat, guinea pig, baboon, little brown bat, Brazilian free-tailed bat, ox, pigeon and quail. In this dataset, maximum lifespan was negatively correlated with H(2)O(2) production at complex I during reverse electron transport. Analysis of residual maximum lifespan and residual H(2)O(2) production revealed that this correlation was even more significant after correction for effects of body mass. To remove effects of phylogeny, independent phylogenetic contrasts were obtained from the residuals. These revealed an inverse association between maximum lifespan and H(2)O(2) production that was significant by sign test, but fell short of significance by regression analysis. These findings indicate that enhanced longevity may be causally associated with low free radical production by mitochondria across species over two classes of vertebrate homeotherms.

Vírus da raiva em quirópteros naturalmente infectados no Estado de São Paulo, Brasil

To identify the species of bats involved in maintaining the rabies cycle; to investigate the distribution of the rabies virus in the tissues and organs of bats and the time taken for mortality among inoculated mice. From April 2002 to November 2003, bats from municipalities in the State of São Paulo were screened for the presence of the rabies virus, by means of direct immunofluorescence. The virus distribution in the bats was evaluated by inoculating mice and N2A cells with 20% suspensions prepared from fragments of different organs and tissues, plus the brain and salivary glands. The time taken for mortality among the mice was monitored daily, following intracerebral inoculation. Out of the 4,395 bats received, 1.9% were found positive for the rabies virus. They belonged to ten genera, with predominance of insectivores. The maximum mean times taken for mortality among the mice following inoculation with brain and salivary gland material were 15.33+/-2.08 days and 11.33+/-2.30 days for vampire bats, 16.45+/-4.48 days and 18.91+/-6.12 days for insectivorous bats, and 12.60+/-2.13 days and 15.67+/-4.82 days for frugivorous bats, respectively. The species infected with the rabies virus were: Artibeus lituratus, Artibeus sp., Myotis nigricans, Myotis sp., Eptesicus sp., Lasiurus ega, Lasiurus cinereus, Nyctinomops laticaudatus, Tadarida brasiliensis, Histiotus velatus, Molossus rufus, Eumops sp. and Desmodus rotundus. Virus investigation in the different tissues and organs showed that the brain and salivary glands were the most suitable sites for virus isolation.

Volatile antimicrobial compounds in the pelage of the Mexican free-tailed bat, Tadarida brasiliensis mexicana

Gas chromatography–mass spectrometry (GC–MS) showed that CH 2Cl 2 extracts of the pelage from the Mexican free-tailed bats, Tadarida brasiliensis mexicana, contained only seven volatile compounds. They include two hydrocarbons, 1-octene and octane; three aldehydes, heptanal, octanal and nonanal; a carboxylic acid, nonanoic acid; and urea. It is likely that nonanal, at an average concentration 0.62 μg/mg hair, and the two homologues, heptanal and octanal found at 0.059 and 0.066 μg/mg hair, respectively, function as antimicrobial agents against mammalian skin bacteria and fungi. These three aldehydes may also act as a chemical protection against bat ectoparasites.

The tiny difference between foraging and communication buzzes uttered by the Mexican free-tailed bat, Tadarida brasiliensis

Echolocating insectivorous bats consummate prey captures using a distinct vocal motor pattern commonly known as the terminal or feeding buzz, which is widely considered a fixed motor pattern executed independently of auditory feedback influences. The Mexican free-tailed bat, Tadarida brasiliensis, offers an opportunity to explore the role of sensory feedback in buzzing because they emit similar buzzes both in flight during foraging and while stationary as communication sounds. Here we compared the spectral and temporal patterns of foraging and communication buzzes to address whether or not auditory feedback may influence buzz patterns. We found that while foraging buzzes uttered in open space were composed of generic FM calls, communication buzzes were composed of an adapted CF-FM call similar to the call type used by T. brasiliensis when navigating in confined spaces. This provides the first evidence that some bats can make significant context-dependent changes in the spectral parameters of calls within their buzz. We also found that inter-pulse intervals, but not call durations, were different within the two buzz types. These observations indicate that though a common pattern generator hierarchically organizes all buzzes, T. brasiliensis retains a significant capacity to adapt the spectral and temporal patterns of elements within its buzzes.

Spectrotemporal Receptive Fields in the Inferior Colliculus Revealing Selectivity for Spectral Motion in Conspecific Vocalizations

Frequency modulations are a prominent feature of animal vocalizations and human speech. Here we investigated how neurons in the inferior colliculus (IC) of Mexican free-tailed bats respond to the frequency-modulated (FM) direction and velocity of complex signals by extracting their spectrotemporal receptive fields (STRFs) using a family of upward- and downward-moving ripple stimuli. STRFs were obtained in more than half of the cells that were sampled. To verify the validity of each STRF, we compared their features both with tone-evoked responses and by convolving the STRF with several conspecific calls. We show that responses to tones are in close agreement with the STRF and that the responses predicted by convolutions compare favorably with responses evoked by those calls. The high predictability showed that the STRF captured most of the excitatory and inhibitory properties of IC cells. Most neurons were selective for the direction and velocity of spectral motion with a majority favoring the downward FM direction, and most had spectrum-time inseparability that correlated with their direction selectivity. Furthermore, blocking inhibition significantly reduced the directional selectivity of these neurons, suggesting that inhibition shapes FM direction selectivity in the IC. Finally, we decomposed the natural calls into their ripple components and show that most species-specific calls have downward-sweeping FM components with sweep velocities that correspond with the preferred sweep velocities of IC neurons. This close quantitative correspondence among features of signals and responses suggests that IC cells are tuned by inhibition to respond optimally to spectral motion cues present in their conspecific vocalizations.

Predictive Occurrence Models for Bat Species in California

Abstract: The ability to accurately predict the potential occurrence of species of management concern is useful for wildlife managers, particularly for those whose management activities involve large areas where sampling is difficult due to logistical or financial constraints. During the summers of 2002 and 2003, we used mist nets to capture bats (Myotis yumanensis, M. californicus, M. evotis, M. thysanodes, Eptesicus fuscus, Lasionycteris noctivagans, Tadarida brasiliensis, Antrozous pallidus, Lasiurus borealis, and Lasiurus cinereus) in Whiskeytown National Recreation Area in north‐central California, USA. We used landscape‐scale variables, logistic regression, and Akaike's Information Criterion (AICc) to model species distributions and produce spatially discerning predictive occurrence maps. We developed a priori models that we used to determine which landscape‐scale variables best discriminated between capture sites and non‐capture sites. The odds of capturing a bat were 3.3 greater when total edge increased by 10,000 m, whereas for Yuma myotis (Myotis yumanensis), the odds of predicting presence were 0.2 greater when distance to lakes and ponds decreased by 2,000 m. Elevation was important in predicting the distribution of silver‐haired bats (Lasionycteris noctivagans) and big brown bats (Eptesicus fuscus). Increasing elevation by 400 m decreased the odds of capturing a silver‐haired bat by 0.1 and a big brown bat by 0.4. Classification accuracy for our models ranged from 80.9% for all bat species combined to 72.3% for Yuma myotis and silver‐haired bats. Predictive occurrence models can be valuable to bat conservation efforts because they provide spatial data important for evaluating the effects of management activities on species distributions.

Bats of Saba, Netherlands Antilles: a zoogeographic perspective

Data presented herein provide records of four species of bats new to the fauna of the Antillean island of Saba — Monophyllus plethodon, Ardops nichollsi, Tadarida brasiliensis, and Molossus molossus. Together with three species previously recorded from the island – Brachyphylla cavernarum, Artibeus jamaicensis, and Natalus stramineus – the chiropteran fauna of the island is documented to be composed of seven species. Our analysis of species/area relationships for West Indian bats provides a slope value of z = 0.177 and R2 = 0.76; therefore, the bat fauna of the West Indies has the flattest slope for this relationship of any West Indian group. This relationship is best explained by a propensity for over water dispersal by West Indian bats. We propose to unite the chiropteran faunas of the islands of Anguilla, Antigua, Barbuda, Nevis, Saba, St. Barthélemy, St. Eustatius, St. Kitts, and St. Martin by recognizing them as the Northern Antillean Faunal Area. Given the small size of Saba (12 km2) and the even smaller effective habitat for non-molossid bats (4 km2), conservation concerns are expressed for the future of the fauna and some recommendations are made for its preservation.

Composition of guano produced by frugivorous, sanguivorous, and insectivorous bats

ABSTRACT Bat guano supports an assemblage of organisms that varies depending on the species of bat producing it. To determine whether these differences in community structure may be due to differences in guano composition, we analyzed guano from frugivorous (Pteropus rodricensis), sanguivorous (Desmodus rotundus), and insectivorous (Tadarida brasiliensis) bats. We found no differences among species in organic matter or lipid of guano. Desmodus guano contained more carbon (C) than Pteropus guano. The latter contained less nitrogen (N), and the former contained less phosphorous (P) than guano of the other two species. Pteropus guano had a higher C:N ratio, and Desmodus guano had higher N:P and C:P ratios than the other two species. These differences in guano composition suggest that guano from bats in different feeding guilds may affect ecosystem structure and dynamics differently.

Organochlorine Pesticide Residues in Guano of Brazilian Free-tailed Bats, Tadarida brasiliensis Saint-Hilaire, from East Texas

Organochlorine Pesticide Residues in Guano of Brazilian Free-tailed Bats, Tadarida brasiliensis Saint-Hilaire, from East Texas

The serotonin releaser fenfluramine alters the auditory responses of inferior colliculus neurons

Local direct application of the neuromodulator serotonin strongly influences auditory response properties of neurons in the inferior colliculus (IC), but endogenous stores of serotonin may be released in a distinct spatial or temporal pattern. To explore this issue, the serotonin releaser fenfluramine was iontophoretically applied to extracellularly recorded neurons in the IC of the Mexican free-tailed bat ( Tadarida brasiliensis). Fenfluramine mimicked the effects of serotonin on spike count and first spike latency in most neurons, and its effects could be blocked by co-application of serotonin receptor antagonists, consistent with fenfluramine-evoked serotonin release. Responses to fenfluramine did not vary during single applications or across multiple applications, suggesting that fenfluramine did not deplete serotonin stores. A predicted gradient in the effects of fenfluramine with serotonin fiber density was not observed, but neurons with fenfluramine-evoked increases in latency occurred at relatively greater recording depths compared to other neurons with similar characteristic frequencies. These findings support the conclusion that there may be spatial differences in the effects of exogenous and endogenous sources of serotonin, but that other factors such as the identities and locations of serotonin receptors are also likely to play a role in determining the dynamics of serotonergic effects.

HABITAT USE BY BATS IN A RIPARIAN CORRIDOR OF THE MOJAVE DESERT IN SOUTHERN NEVADA

We used a combination of capture and acoustic monitoring equipment to examine use of habitat by bats in a desert riparian community in southern Nevada. Each habitat type (riparian marsh, mesquite bosque, riparian woodland, and riparian shrubland) was simultaneously and continuously sampled acoustically in 3- to 5-night increments for 54 nights between June 2000 and January 2001. Fifteen species of bats were detected acoustically, 13 of which were captured using harp traps or mist nets. Five species were not detected frequently enough to be included in statistical analyses. California leaf-nosed bats (Macrotus californicus) and Brazilian free-tailed bats (Tadarida brasiliensis) were generalists, spending equal amounts of time in each habitat. Western yellow bats (Lasiurus xanthinus) and pallid bats (Antrozous pallidus) demonstrated strong biases for riparian woodland over the other habitats sampled. The remaining 6 species spent substantially more time in at least 1 of the 4 habitats. Riparian woodlands accounted for more than 50% of all bat activity, whereas riparian marshes were the least used habitat. High species richness and differences in habitat use by most species emphasizes the importance of a diversity of riparian habitats for bats at the study site. The existence of both native and nonnative habitat may elevate bat species richness and increase the degree of differential habitat use to levels higher than would be expected if only native habitat existed at the study site. Understanding differential riparian habitat use by bats in desert ecosystems may have profound management implications.

DIETARY STUDY OF BIG FREE-TAILED BATS (NYCTINOMOPS MACROTIS) IN BIG BEND NATIONAL PARK, TEXAS

Abstract Nyctinomops macrotis, the big free-tailed bat, is relatively uncommon in the southwestern United States, and diet information for this species is sparse. The objective of this study was to examine the diet of N. macrotis in Big Bend National Park, Texas, by using fecal analysis to determine what these bats ate in an area where they were sympatric with 3 other species of free-tailed bats. We collected and analyzed fecal samples from 40 individuals and obtained the following results: Lepidoptera (87.5% volume, 100% frequency), Hemiptera (4.1% volume, 22.5% frequency), Coleoptera (4.6% volume, 17.5% frequency), Orthoptera (1.1% volume, 12.5% frequency), unidentified insects (2.4% volume, 30.0% frequency). The diet of N. macrotis largely overlapped that of the Mexican free-tailed bat (Tadarida brasiliensis) and pocketed free-tailed bat (Nyctinomops femorosaccus) in Big Bend National Park. However, N. macrotis consumed significantly more lepidopterans and significantly less hemipterans and coleopteran...

Economic value of the pest control service provided by Brazilian free-tailed bats in south-central Texas

Brazilian free-tailed bats (Tadarida brasiliensis) form enormous summer breeding colonies, mostly in caves and under bridges, in south-central Texas and northern Mexico. Their prey includes several species of adult insects whose larvae are known to be important agricultural pests, including the corn earworm or cotton bollworm (Helicoverpa zea). We estimate the bats' value as pest control for cotton production in an eight-county region in south-central Texas. Our calculations show an annual value of $741 000 per year, with a range of $121 000–$1 725 000, compared to a $4.6–$6.4 million per year annual cotton harvest.