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At least 325 records · Page 18Linked to original sources
PubMed1998

Roost selection in the pipistrelle bat, Pipistrellus pipistrellus (Chiroptera: Vespertilionidae), in northeast Scotland.

Availability of suitable roost sites may limit bat distribution and abundance. We compared nine internal and 26 external features of 21 known roost buildings with those of 17 random buildings in northeast Scotland, U.K. (57 degreesN) to assess whether pipistrelle bats, Pipistrellus pipistrellus (55-kHz phonotype) are selective in their use of roosts. Bats did not select roosts with specific structural attributes. Compared with random buildings, roosts were closer to a tree over 10 m tall and had a greater percentage cover (of trees over 10 m tall) within a radius of 50 m. Trees may provide benefits by providing shelter and thus ameliorating the microclimate of the roost. Cover may also provide protection from predators so that bats are able to emerge earlier, thus increasing foraging time. Bats in the present study emerged 11 min earlier from roosts with 29% cover than from roosts with 3% cover, potentially gaining as much as 10% of their daily energy requirements in this extra time. Roosts were also more likely to have linear vegetation elements leading away from them. These features may be important for navigation, foraging or predator avoidance. Compared with random buildings roosts were closer to and surrounded by a greater area of deciduous woodland within a radius of 0.5 km, had a greater area of coniferous woodland within a radius of 0.5 km, and were more likely to be found within 0.5 km of a major river. All these factors are likely to be beneficial for foraging. A logistic regression model indicated that percentage cover within 50 m of the building was the best predictor of the presence or absence of bats roosting in a building. Copyright 1998 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1999

Noctuid moths show neural and behavioural responses to sounds made by some bat-marking rings.

Coloured rings are often used for marking bats so that specific individuals can be recognized. We noticed that the rings of mouse-eared bats, Myotis myotis and Myotis blythii, in a combination of one plastic-split and one metallic ring on the same forearm, emitted sounds that were largely ultrasonic each time the rings met in flight. We recorded the ring sounds and the echolocation calls produced by the bats, and played them back to neural preparations of lesser yellow underwing moths, Noctua comes, while making extracellular recordings from the moths' A1 auditory receptors. The peak energy of the ring sounds occurred much closer in frequency to the moth's best auditory frequency (the frequency at which the moth has the lowest auditory threshold) than the peak energy of the calls, for both bat species, and the ring sounds were detected at a threshold 5-6 dB peSPL lower than the calls. Moths performed evasive manoeuvres to playbacks of ring sounds more frequently than they did to control (tape noise) sequences. These neural and behavioural responses imply that certain bats should not be marked with two rings on one wing, as this may make the bat more apparent to tympanate insects, and may therefore reduce its foraging success. Copyright 1999 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed2005

Australian bat lyssavirus: a recently discovered new rhabdovirus.

Australian bat lyssavirus (ABLV), first identified in 1996, has been associated with two human fatalities. ABLV is genetically and serologically distinct from, but is closely related to, classical rabies. It has a bullet-shaped morphology by electron microscopy. There are two strains of ABLV known: one circulates in frugivorous bats, sub-order Megachiroptera, and the other circulates in the smaller, mainly insectivorous bats, sub-order Microchiroptera. Each strain has been associated with one human fatality. Surveillance indicates infected bats are widespread at a low frequency on the Australian mainland. It is unclear how long ABLV has been present in Australia, although molecular clock studies suggest the two strains separated 950 or 1,700 years ago based on synonymous or non-synonymous nucleotide changes, respectively. Recent serological surveys suggest a closely related virus may exist in the Philippines. Due to demonstrated cross-protection in mice, rabies vaccine is used to prevent infection. Rabies post-exposure prophylaxis (PEP) protocols have been adopted for when a human is scratched or bitten by a suspect bat. A long-term commitment to public health programs that test bats that have been involved in scratch or bite incidents, followed by PEP if appropriate, will be necessary to minimise further human infection.

Animals↗
PubMed1995

Frequency modulated sound pattern analysis in the lesser bulldog bat: the role of interactions between adjacent frequency elements of complex sounds.

A stereotyped approach phase vocalization response of Noctilio albiventris to artificial echoes simulating a virtual approaching object was used to assess the ability of the bat to analyze and extract distance information from the artificial echoes. The performance of the bats depended on the temporal pattern of frequency change of the continuously sweeping frequency modulated (FM) component of the signals. When the bats were presented with a CF/FM signal containing a time-reversed upward FM sweep, they responded with approach phase behavior at a performance level that was significantly below that seen with a CF/FM signal containing a naturally structured downward FM sweep. When the FM sweep was divided into a series of brief pure tone steps, the extent to which the bats showed a difference in their capability to process upward versus downward FM sweeps depended on the difference in frequency between the pure tone steps. The bats effectively processed downward but not upward FM sweeps when the difference in frequency between pure tone frequency elements of the FM sweeps was from about 100-200 Hz, but they effectually processed both downward and upward FM sweeps when the tonal elements composing the FM sweeps were separated by more than about 200 Hz. This suggests that the ability of the bats to effectively process downward but not upward FM sweeps is based on local interactions between adjacent frequency elements of the complex sounds.

Animals↗
PubMed1993

Labile cochlear tuning in the mustached bat. I. Concomitant shifts in biosonar emission frequency.

The cochlea of the mustached bat (Pteronotus parnellii) has sharp tuning characteristics and pronounced resonance within a narrow band near the second harmonic, constant frequency (CF2) component of the animal's biosonar signals. That fine frequency discrimination occurs within this narrow band is evident from Doppler-shift compensation, whereby bats in flight lower the frequency of emitted CF2s to maintain returning echoes within this band. This study examined various factors capable of producing shifts in both the cochlear resonance frequency (CRF) and CF2s emitted by stationary bats and bats actively Doppler-shift compensating on a pendulum. Each of three experimental factors shifted the CRF in a reversible manner. Changes in body temperature produced an average CRF shift of 39 +/- 18 Hz/degrees C. The CRF increased with flight by 150 +/- 100 Hz and returned to baseline values within 10 min after flight. Contralateral sound exposure produced smaller (100 +/- 20 Hz), rapid shifts in the CRF, suggesting that a mechanism different from the temperature- and flight-related shifts was involved. Changes in the CRF induced by temperature and flight were accompanied by shifts in the emitted CF2 of stationary and moving bats. Coupled with a companion study of associated shifts in neural tuning, the concomitant changes in CRF and CF2 provide evidence of cochlear tuning lability in the mustached bat.

Acoustic Stimulation↗
PubMed1991

Arctiid moth clicks can degrade the accuracy of range difference discrimination in echolocating big brown bats, Eptesicus fuscus.

Four big brown bats (Eptesicus fuscus) born and raised in captivity were trained using the Yes/No psychophysical method to report whether a virtual sonar target was at a standard distance or not. At threshold bats were able to detect a minimum range difference of 6 mm (a delta t of 36 microseconds). Following threshold determinations, a click burst 1.8 ms long containing 5 pulses from the ruby tiger moth, Phragmatobia fuliginosa (Arctiidae), was presented randomly after each phantom echo. The sound energy of the click burst was -4 dB relative to that of the phantom echo. Clicks presented for the very first time could startle naive bats to different degrees depending on the individual. The bats' performance deteriorated by as much as 4000% when the click burst started within a window of about 1.5 ms before the phantom echo. Even when one of ten phantom echoes was preceded by a click burst, the range difference discrimination worsened by 200%. Hence, clicks falling within the 1.5 ms time window seem to interfere with the bat's neural timing mechanism. The clicks of arctiid moths appear to serve 3 functions: they can startle naive bats, interfere with range difference determinations, or they can signal the moth's distastefulness, as shown in earlier studies.

Animals↗
PubMed1994

Complex sound analysis in the lesser bulldog bat: evidence for a mechanism for processing frequency elements of frequency modulated signals over restricted time intervals.

A stereotypical approach phase vocalization response of the lesser bulldog bat, Noctilio albiventris, to artificial echoes simulating a virtual approaching object was used to assess the ability of the bat to analyze and extract distance information from the artificial echoes. The performance of the bat was not significantly different when presented with naturally structured CF/FM echoes containing FM elements that sweep continuously from about 75-55 kHz in 4 ms or with CF/FM echoes containing FM components constructed from a series of 98 pure tone frequency steps, each with a duration of 0.04 ms. The performance of the bat remained unchanged when the duration of the tone steps was increased up to 0.08 ms but declined sharply to a level that was significantly below that seen with a naturally structured echo when the steps were 0.09 ms or longer. The performance of the bat depended on the duration of the individual tone steps, which could not exceed a specific upper limit of about 0.08 ms. The study suggests that the bats have adaptations for processing individual narrow band segments of FM signals over specific time intervals.

Animals↗
PubMed1987

Ontogenesis of the echolocation system in the rufous horseshoe bat, Rhinolophus rouxi (audition and vocalization in early postnatal development).

1. The development of vocalization and hearing was studied in Sri Lankan horseshoe bats (Rhinolophus rouxi) during the first postnatal month. The young bats were caught in a nursing colony of rhinolophids in which birth took place within a two week period. 2. The new-born bats emitted isolation calls through the mouth. At the beginning these calls consisted of pure tones with frequencies below 10 kHz (Fig. 1). During the first postnatal week the call frequency increased to about 15 kHz, and the fundamental was augmented by two to four harmonics. No evoked potentials to pure tone stimuli could be elicited in the inferior colliculus of this age group, i.e., auditory processing at the midbrain level was not demonstrable. 3. Evoked potentials were first recorded in the second week, broadly tuned to 15-45 kHz, with a maximum sensitivity between 15-25 kHz. In the course of the second week, however, higher frequencies up to 60 kHz became progressively incorporated into the audiogram (Fig. 3). The fundamental frequency of the multiharmonic isolation calls, emitted strictly through the mouth, increased to about 20 kHz. 4. In the bats' third postnatal week an increased hearing sensitivity (auditory filter) emerged, sharply tuned at frequencies between 57 and 60 kHz (Fig. 4e). The same individuals were also the first to emit long constant frequency echolocation calls through the nostrils (Fig. 4c). The energy of the calls was arranged in harmonic frequency bands with the second harmonic exactly tuned to the auditory filter. These young bats continued to emit isolation calls through the mouth, which were, however, not harmonically related to the echolocation calls (Fig. 4b, d). 5. During the fourth week, both the auditory filter and the matched echolocation pulses (the second harmonic) shifted towards higher frequencies (Fig. 5). During the fifth week the fundamental frequency of the calls was progressively attenuated, and both the second harmonic of the pulses and the auditory filter reached the frequency range typical for adult bats of 73-78 kHz (Fig. 6). 6. The development of audition and vocalization is discussed with regard to possible interactions of both subsystems, and their incorporation into the active orientation system of echolocation.

Aging↗
PubMed1987

The echolocation and hunting behavior of the bat, Pipistrellus kuhli.

The echolocation and hunting behavior of Pipistrellus kuhli was studied in the field using multi-exposure photography synchronized with high-speed tape recordings. During the search phase, the bats used 8-12 ms signals with sweeps (sweep width 3-6 kHz) and pulse intervals near 100 ms or less often near 200 ms. The bats seemed to have individual terminal frequencies that could lie between 35 and 40 kHz. The duty cycle of searching signals was about 8%. The flight speed of hunting bats was between 4.0 and 4.5 m/s. The bats reacted to insect prey at distances of about 70 to 120 cm. Given the flight speed, the detection distance was estimated to about 110 to 160 cm. Following detection the bat went into the approach phase where the FM sweep steepened (to about 60 kHz bandwidth) and the repetition rate increased (to about 30 Hz). The terminal phase or 'buzz', which indicates prey capture (or attempted capture), was composed of two sections. The first section contained signals similar to those in the approach phase except that the pulse duration decreased and the repetition rate increased. The second section was characterized by a sharp drop in the terminal frequency (to about 20 kHz) and by very short pulses (0.3 ms) at rates of up to 200 Hz. Near the beginning of the buzz the bat prepared for capturing the prey by extending the wings and forming a tail pouch. A pause of about 100 ms in sound emission after the buzz indicated a successful capture (Fig. 4).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Pathogenesis of rabies virus from a Danish bat (Eptesicus serotinus): neuronal changes suggestive of spongiosis.

Rabies virus strains isolated from a European bat (Eptesicus serotinus) in Denmark (DBV), a North American big brown bat (Eptesicus fuscus) in New York State (NY-bat), and a human in South Africa (Duvenhage strain (DUV-1) were studied by using a panel of monoclonal antibodies and by inoculating mice, cats, and dogs. The ten Danish virus isolates from the same bat species reacted identically with a panel of monoclonal antibodies. Immunofluorescence, monoclonal antibody, and histopathologic studies showed that the Danish bat isolates were similar to Duvenhage, and to some degree, to classical rabies virus. All isolates produced fatal infections in mice when inoculated by the intracerebral, footpad, and oral routes. Dogs and cats inoculated intracerebrally with the DBV and DUV-1 virus strains died of rabies-like illnesses within 10 days. Although no dogs that were inoculated intramuscularly or intravenously showed signs of disease, all developed neutralizing antibodies and resisted challenge with lethal dose of street rabies virus. All dogs inoculated with the NY-bat virus, with the exception of those inoculated intravenously, showed classical signs of rabies and one of the intramuscularly inoculated dogs recovered. Cats inoculated intramuscularly also died of rabies-like illness within 15 days. At necropsy, rabies antigen was detected by immunofluorescence in frozen sections of several organs, including brain and salivary glands. Histopathologic and electron microscopic studies of the central nervous system of mice, dogs and cats that died of DBV infection showed neuronal cytoplasmic changes considered to be a form of spongiosis.

Animals↗
PubMedDate not supplied

Two methods for recommending bat weights.

Baseball players swung very light and very heavy bats through our instrument and the speed of the bat was recorded. These data were used to make mathematical models for each person. Then these models were coupled with equations of physics for bat-ball collisions to compute the Ideal Bat Weight for each individual. However, these calculations required the use of a sophisticated instrument that is not conveniently available to most people. So, we tried to find items in our database that correlated with Ideal Bat Weight. However, because many cells in the database were empty, we could not use traditional statistical techniques or even neural networks. Therefore, three new methods were used to estimate the missing data: (i) a neural network was trained using subjects that had no empty cells, then that neural network was used to predict the missing data, (ii) the data patching facility of a commercial software package was used, and (iii) the empty cells were filled with random numbers. Then, using these fully populated databases, several simple models were derived for recommending bat weights.

Adolescent↗
PubMed2005

Acoustic mirror effect increases prey detection distance in trawling bats.

Many different and phylogenetically distant species of bats forage for insects above water bodies and take insects from and close to the surface; the so-called 'trawling behaviour'. Detection of surface-based prey by echolocation is facilitated by acoustically smooth backgrounds such as water surfaces that reflect sound impinging at an acute angle away from the bat and thereby render a prey object acoustically conspicuous. Previous measurements had shown that the echo amplitude of a target on a smooth surface is higher than that of the same target in mid-air, due to an acoustic mirror effect. In behavioural experiments with three pond bats (Myotis dasycneme), we tested the hypothesis that the maximum distances at which bats can detect prey are larger for prey on smooth surfaces than for the same prey in an airborne situation. We determined the moment of prey detection from a change in echolocation behaviour and measured the detection distance in 3D space from IR-video recordings using stereo-photogrammetry. The bats showed the predicted increase in detection distance for prey on smooth surfaces. The acoustic mirror effect therefore increases search efficiency and contributes to the acoustic advantages encountered by echolocating bats when foraging at low heights above smooth water surfaces. These acoustic advantages may have favoured the repeated evolution of trawling behaviour.

Animals↗
PubMed2006

Use of artificial roost structures by bats at the Indianapolis International Airport.

From 1992-1996, 3204 artificial roosts of 9 types were placed in woodlots near Indianapolis International Airport in an effort to provide habitat for the federally-endangered Indiana myotis (Myotis sodalis) and to determine the feasibility of using these structures to manage bats in a rapidly developing suburban area. We surveyed these structures at least annually during 1992-1999 and found only northern myotis (Myotis septentrionalis) regularly using the structures. Four other species were occasionally found using structures including big brown bats (Eptesicus fuscus, n=14 individuals), little brown myotis (Myotis lucifugus, n=2), Indiana myotis (Myotis sodalis, n=2), and one silver-haired bat (Lasionycteris noctivagans). Single, triple, and Missouri-style batboxes were almost always used, rather than the six other types of experimental roosts that had been in place. However, after 10 years in place, it appears that Indiana bats are acclimated to boxes, as 6 of them were being used rather regularly by Indiana myotis. Bat boxes can provide roosting habitat for some species under conditions where few suitable roosts exist, but assuring an abundance of natural habitats is usually more desirable for conservation of tree-roosting bats.

Acclimatization↗
PubMed2002

Orienting responses and vocalizations produced by microstimulation in the superior colliculus of the echolocating bat, Eptesicus fuscus.

An echolocating bat actively controls the spatial acoustic information that drives its behavior by directing its head and ears and by modulating the spectro-temporal structure of its outgoing sonar emissions. The superior colliculus may function in the coordination of these orienting components of the bat's echolocation system. To test this hypothesis, chemical and electrical microstimulation experiments were carried out in the superior colliculus of the echolocating bat, Eptesicus fuscus, a species that uses frequency modulated sonar signals. Microstimulation elicited pinna and head movements, similar to those reported in other vertebrate species, and the direction of the evoked behaviors corresponded to the site of stimulation, yielding a map of orienting movements in the superior colliculus. Microstimulation of the bat superior colliculus also elicited sonar vocalizations, a motor behavior specific to the bat's acoustic orientation by echolocation. Electrical stimulation of the adjacent periaqueductal gray, shown to be involved in vocal production in other mammalian species, elicited vocal signals resembling acoustic communication calls of E. fuscus. The control of vocal signals in the bat is an integral part of its acoustic orienting system, and our findings suggest that the superior colliculus supports diverse and species-relevant sensorimotor behaviors, including those used for echolocation.

Acoustics↗
PubMed2002

The effect of preceding sonar emission on temporal integration in the bat, Megaderma lyra.

The present study investigated whether and to which extent temporal integration in bats is influenced by echolocation behavior. One way to quantify temporal integration is to measure the detection threshold for a pair of short tone pips as a function of the temporal separation between the pips. To asses the effect of preceding sonar emission on temporal integration in the bat, Megaderma lyra, the detection thresholds of identical subjects were measured in a passive as well as in an active paradigm. In the passive paradigm, the presentation of the pip pairs was independent of the bats' sonar emissions; in the active paradigm, the presentation was triggered by the bats' sonar emissions. In both cases, the bats showed a very short integration time in the range of 100-200 micros. Moreover, the comparison of the active and passive results within each bat revealed no systematic differences in the two measuring paradigms. These results indicate that temporal integration is not influenced by echolocation. Simulations with a computer model of cochlear filtering based on measurements of M. lyra cochlear tuning suggest that the perceptual temporal integration is dominated by the integration of the cochlear filters.

Animals↗
PubMed2006

Intra-individual variation in the vocalized frequency of the Taiwanese leaf-nosed bat, Hipposideros terasensis, influenced by conspecific colony members.

We examined the intra-individual variation in resting frequency of the constant-frequency component of the second harmonic of the pulse (F (rest)) over 4 years in a laboratory colony of the Taiwanese leaf-nosed bat (Hipposideros terasensis). Patterns of change in F (rest) were observed when individuals were added to or removed from the colony so that we investigated whether F (rest) was affected by neighboring colony members. F (rest) of each bat continually showed a long-term gradual change throughout the year, and all bats in the colony increased or decreased their F (rest) in the same direction as a group non-seasonally. The greatest short-term changes were observed when new bats with a relatively low F (rest) joined the colony and F (rest) of new bats converged with those of the original colony members around 8 -16 days after their introduction. Conversely, a single individual showed sudden short-term decrease in F (rest) after its isolation from other colony members. These findings strongly indicate that F (rest) is flexible according to the presence of neighboring conspecific bats. We suggest that the audio-vocal feedback for conspecific pulses appears to be involved in the short- or long-term intra-individual variation in F (rest) other than factors previously thought such as age or season.

Adaptation, Physiological↗
PubMed2000

Sulphur-containing "perfumes" attract flower-visiting bats.

We tested the attractiveness of individual scent compounds of bat-pollinated flowers to their pollinators, small flower-visiting bats of the genus Glossophaga (Phyllostomidae). Twenty compounds belonging to four different chemical substance classes were tested, both in the laboratory and in the field. In the laboratory, the bats (Glossophaga soricina) approached odour sources spontaneously and without preceding experience. Without ever receiving any reward they preferred the scent of a sulphur-containing compound, dimethyl disulphide, to several other odour components emitted by bat-pollinated flowers, and to scentless controls. In the field, at La Selva station in the tropical lowland rain forest of Costa Rica, G. commissarisi were attracted by two sulphur-containing compounds, dimethyl disulphide and 2,4-dithiapentane, to visit artificial flowers filled with sugar water. Thus, in nectarivorous bats the sense of smell obviously plays an important role in searching for and localising food sources, and even single components of the scent bouquets of bat-pollinated flowers are attractive. The preference for sulphur-containing odours seems to be innate.

Animals↗
PubMed1997

Detection of jitter in intertarget spacing by the big brown bat Eptesicus fuscus.

We trained bats to detect intertarget jitter, i.e., relative motion between two virtual (electronically synthesized) targets. Both targets were themselves moving with respect to nearby objects (e.g., the microphone and speaker used to create the virtual targets) so that the only reliable cue available to the bats was variation in intertarget spacing. Given a target at 80 cm and another at 95, 110 or 125 cm, the threshold for intertarget jitter (ITJ) of the two bats tested was < 10 microseconds, corresponding to < 1.7 mm of range. When, for one bat, we increased the range instability of the targets by adding varying amounts of random range shift to the target complex (while preserving the correct intertarget spacing), ITJ threshold worsened. When we presented three targets, one of which was jittering, the bat's threshold improved to 0.9 microsecond (equivalent to 0.16 mm). If no second target was presented, i.e., if the task was to detect jitter added to a single moving target, then bats' jitter threshold was very high (> 200 microseconds). Eptesicus fuscus appears to be very good at detecting changes in intertarget spacing, which might prove valuable for detecting targets moving relative to the background or for constructing a spatial image of a complex environment.

Animals↗