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PubMed1995

The arrangements of F-actin, tubulin and fodrin in the organ of Corti of the horseshoe bat (Rhinolophus rouxi) and the gerbil (Meriones unguiculatus).

The composition of cytoskeletal elements in hair cells and non-sensory cells was studied in paraformaldehyde fixed cochleae of the horseshoe bat and the gerbil using phallotoxins and antibodies directed against actin, alpha-tubulin and fodrin. In both species, cryostat sections of the organ of Corti were studied using confocal fluorescence microscopy; in the bat, ultrathin sections were investigated using actin-immunoelectron and classical electron microscopy. F-actin was found in stereocilia and cuticular plates of inner and outer hair cells (IHCs and OHCs) of both species. In fixed material from both species, no F-actin staining was detected in the cytoplasm or along the lateral cell membrane of OHCs, whereas in freshly isolated OHCs of the gerbil, a faint F-actin staining was detected along the lateral wall. In the bat, the patterns of F-actin staining were confirmed with actin-immunoelectron microscopy. The alpha-tubulin antibody strongly labeled IHCs of both species. They contained a complex network of microtubules especially in the neck portion. In the bat, OHCs showed no distinct alpha-tubulin reactivity, as would be expected given the scarcity of microtubules observed at the ultrastructural level. In the gerbil, alpha-tubulin reactivity was found throughout the OHC body with highest intensity in the cell apex. In Deiters cells, pillar cells and Boettcher cells of both species, F-actin and microtubules were colocalized at contact zones with the basilar membrane. In Deiters cups, F-actin staining was most pronounced in the basal turn of the bat cochlea. In the gerbil, a distinct baso-apical gradient was found in immunostaining properties and morphology of the Deiters cells. Intense fodrin reactivity was found in the cuticular plates and along the lateral cell membrane of both types of hair cells of the bat. Cytoplasmic fodrin staining was localized within the IHCs of the bat. In the gerbil, intense fodrin staining was only found in cuticular plates of hair cells and staining of the lateral cell membrane of hair cells was faint. A faint fodrin staining was also seen in Deiters cells of both species. The basic arrangement of the cytoskeletal elements in the batś organ of Corti is similar to that of other mammals, however, certain features suggest the presence of subtle differences in micromechanical properties: there is an increased concentration of microtubules in the neck portion of IHCs, an increase in the amount of F-actin within the Deiters cups and a reduced amount of microtubules in the OHCs.

Actins↗
PubMed2006

Keeping up with bats: dynamic auditory tuning in a moth.

Many night-flying insects evolved ultrasound sensitive ears in response to acoustic predation by echolocating bats . Noctuid moths are most sensitive to frequencies at 20-40 kHz , the lower range of bat ultrasound . This may disadvantage the moth because noctuid-hunting bats in particular echolocate at higher frequencies shortly before prey capture and thus improve their echolocation and reduce their acoustic conspicuousness . Yet, moth hearing is not simple; the ear's nonlinear dynamic response shifts its mechanical sensitivity up to high frequencies. Dependent on incident sound intensity, the moth's ear mechanically tunes up and anticipates the high frequencies used by hunting bats. Surprisingly, this tuning is hysteretic, keeping the ear tuned up for the bat's possible return. A mathematical model is constructed for predicting a linear relationship between the ear's mechanical stiffness and sound intensity. This nonlinear mechanical response is a parametric amplitude dependence that may constitute a feature common to other sensory systems. Adding another twist to the coevolutionary arms race between moths and bats, these results reveal unexpected sophistication in one of the simplest ears known and a novel perspective for interpreting bat echolocation calls.

Acoustic Stimulation↗
PubMed2006

The evolutionary history and dynamics of bat rabies virus.

Rabies virus (RABV) is endemic in terrestrial mammals throughout the world and in bats on the American continent. We performed the most extensive phylogenetic analyses of bat RABV sequences undertaken to date using a variety of genes. Our study supported previous suggestions that viral sequences are grouped according to the behaviour of the host species. However, there was more genetic and geographical diversity within each phylogenetic group than previously recognised, including evidence for new groups. Furthermore, three clades of Latin American bat RABV that were distinct from the previously identified "group IV" bat RABV clade and more closely related to North American bat RABV clades, were identified. Strikingly, phylogenetic trees for the G (glycoprotein) gene had a significantly different evolutionary history to those inferred for the N (nucleoprotein) and P (phosphoprotein) genes, and an analysis of these competing topologies revealed that it is not possible on current data to resolve whether bat RABV arose from terrestrial mammal RABV, or vice-versa. Finally, using coalescent approaches, we estimated that RABV had similar rates of population growth and nucleotide substitution (approximately 2.5-4x10(-4) substitutions per site, per year) in both bats and terrestrial mammals, despite underlying differences in epidemiology.

Animals↗
PubMed2006

[A new case of bat rabies in France].

INTRODUCTION: Bat rabies represents an emerging zoonosis in Europe and the only endemic cause of rabies in France. CASE RECORD: A 29 year-old woman was bitten at the hand by a bat. The diagnosis of bat rabies was positive and the viral strain was an European Bat Lyssavirus 1a. A combination of rabies vaccine and human rabies immune globulin was provided to the patient. DISCUSSION: Any direct contact with a bat must be avoided. In case of exposure to bats, the postexposure treatment must associate the rabies vaccine and human rabies immune globulin because of antigenic diversity of Lyssavirus circulating in bat species.

Adult↗
PubMed2006

Molecular cloning and sequencing of the cDNA encoding the bat CD4.

Chiroptera is thought to be a vector or a natural reservoir of various pathogenic microbes. However, there are few basic studies on the subject of chiroptera immune systems. This is the first report to determine the sequence of bat CD4 cDNA. Comparison with other animals' CD4 and phylogenetic analysis have shown that bat CD4 had a higher homology to cat and dog CD4 than to human and mouse CD4. Moreover, from the analysis of the structure of the CD4 Ig-like C-type 1 region, in bat CD4 there was an insertion of 18 extra amino acids. In addition, bat CD4 lacked cystein, which suggested that the disulfide bond could not be formed. Human, monkey and mouse CD4 have the cystein and the disulfide bond, but pig, cat, whale and dog CD4, like that of the bat, lacked the cystein. We conducted the present study in order to help elucidate the infectious diseases derived from the bat as well as bat immune systems.

Amino Acid Sequence↗
PubMed2002

Cryptogenic rabies, bats, and the question of aerosol transmission.

Human rabies is rare in the United States; however, an estimated 40,000 patients receive rabies postexposure prophylaxis each year. Misconceptions about the transmission of rabies are plentiful, particularly regarding bats. Most cases of human rabies caused by bat variants have no definitive history of animal bite. Three hypotheses are proposed and reviewed for the transmission of rabies from bats to human beings. They include nonbite transmission (including aerosol transmission), the alternate host hypothesis (an intermediate animal host that acquires rabies from a bat and then transmits rabies to human beings), and minimized or unrecognized bat bites. Nonbite transmission of rabies is very rare, and aerosol transmission has never been well documented in the natural environment. The known pathogenesis of rabies and available data suggest that all or nearly all cases of human rabies attributable to bats were transmitted by bat bites that were minimized or unrecognized by the patients.

Adult↗
PubMed2006

Interdigital webbing retention in bat wings illustrates genetic changes underlying amniote limb diversification.

Developmentally regulated programmed cell death sculpts the limbs and other embryonic organs in vertebrates. One intriguing example of species-specific differences in apoptotic extent is observed in the tissue between the digits. In chicks and mice, bone morphogenetic proteins (Bmps) trigger apoptosis of the interdigital mesenchyme, leading to freed digits, whereas in ducks, Bmp antagonists inhibit the apoptotic program, resulting in webbed feet. Here, we show that the phyllostomid bat Carollia perspicillata utilizes a distinct mechanism for maintaining interdigit tissue. We find that bat forelimb and hindlimb interdigital tissues express Bmp signaling components but that only bat hindlimbs undergo interdigital apoptosis. Strikingly, the retention of interdigital webbing in the bat forelimb is correlated with a unique pattern of Fgf8 expression in addition to the Bmp inhibitor Gremlin. By using a functional assay, we show that maintenance of interdigit tissue in the bat wing depends on the combined effects of high levels of Fgf signaling and inhibition of Bmp signaling. Our data also indicate that although there is not a conserved mechanism for maintaining interdigit tissue across amniotes, the expression in the bat forelimb interdigits of Gremlin and Fgf8 suggests that these key molecular changes contributed to the evolution of the bat wing.

Animals↗
PubMed2005

Batting last as a home advantage factor in men's NCAA tournament baseball.

In baseball and softball, there is a rule that allows the home team to have the last at-bat and thus the final opportunity to win the game. However, in tournament play, this rule is often set aside and, instead, batting order is decided by other means (e.g. tournament rules, the flip of a coin). The purpose of this study was to examine the impact of the batting last rule on game outcome in NCAA men's regional tournament baseball. It was hypothesized that host (i.e. home) teams would win a greater percentage of the games in which they batted last compared with when they batted first. This hypothesis was not supported. Closer examination of the last inning of play showed home teams were no more likely to have won the game during their last bat than visitors playing other visitors. The results suggest that the batting last rule contributes minimally, if at all, to home advantage in NCAA tournament baseball.

Adult↗
PubMed1998

Kinematics and kinetics of the drive off the front foot in cricket batting.

A cinematographic analysis of the drive off the front foot (D) and the forward defensive stroke (FD) was undertaken to establish the kinematic and kinetic factors involved in playing these strokes against medium-fast bowling. Fourteen provincial cricket batsmen were filmed at 100 Hz while batting on a turf pitch with a specially instrumented bat. Results for the drive off the front foot revealed that the movement and stroke pattern were generally supportive of the coaching literature, with the forward defensive stroke forming the basis of the drive. Certain mechanical differences, although non-significant, were evident to facilitate the attacking nature of the front foot drive and included a higher backlift (FD = 0.65 m; D = 0.74 m), later commencement of the stride (FD = 0.64 s pre-impact; D = 0.58 s pre-impact) and downswing of the bat (FD = 0.38 s pre-impact; D = 0.36 s pre-impact), a shorter front foot stride (FD = 0.72 m; D = 0.68 m) with the front foot placement taking place later (FD = 0.14 s pre-impact; D = 0.06 s pre-impact), and the back foot dragging further forward at impact (FD = 0.05 m; D = 0.10 m). The front upper limb moved as a multi-segmental series of levers, which resulted in the drive showing significantly greater (P< 0.05) peak bat horizontal velocity at 0.02 s pre-impact (FD = 3.53 +/- 3.44 m s(-1); D = 11.8 +/- 4.61 m x s(-1)) and 0.02 s post-impact (FD = 2.73 +/- 2.88 m x s(-1); D = 11.3 +/- 4.21 m x s(-1)). The drive showed a significantly greater (P < 0.05) bat-ball closing horizontal velocity (FD = 24.2 +/- 4.65 m x s(-1); D = 32.3 +/- 5.06 m x s(-1)) and post-impact ball horizontal velocity (FD = 6.85 +/- 5.12 m x s(-1); D = 19.5 +/- 2.13 m x s(-1)) than for the forward defensive stroke. The point of bat-ball contact showed nonsignificant differences, but occurred further behind the front ankle (FD = 0.09 +/- 0.17 m; D = 0.20 +/- 0.13 m), with the bat more vertical at impact (FD = 62.6 +/- 6.53 degrees ; D = 77.8 +/- 7.05 degrees). Significant differences (P< 0.01) occurred between the grip forces of the top and bottom hands for the two strokes, with the principal kinetic finding that the top hand plays the dominant role during the execution of the drive with the bottom hand reinforcing it at impact. Similar grip force patterns for the two strokes occurred during the initial part of the stroke, with the drive recording significantly greater (P < 0.05) forces at 0.02 s pre-impact (top hand: FD = 129 +/- 41.6 N; D = 199 +/- 40.9 N; bottom hand: FD = 52.2 +/- 16.9 N; D = 91.8 +/- 41.1 N), at impact (top hand: FD = 124 +/- 29.3 N; D = 158 +/- 56.2 N; bottom hand: FD = 67.1 +/- 21.5 N; D = 86.2 +/- 58.2 N) and 0.02 s post-impact (top hand: FD = 111 +/- 22.2 N; D = 126 +/- 28.5 N; bottom hand: FD = 65.5 +/- 26.9 N; D = 82.4 +/- 28.6 N).

Adult↗
PubMed1964

CYTOCHEMICAL DIFFERENCES IN KIDNEYS FROM WINTER HIBERNATING AND AROUSED BATS (MYOTIS LUCIFUGUS), WITH PARTICULAR REFERENCE TO THE GOLGI ZONE.

Kidneys from winter bats (Myotis lucifugus) were removed and fixed in cold formalin-calcium while the animals were in the following states: (a) natural hibernation; (b) arousal from hibernation for 24 hours; (c) laboratory maintained hibernation; and (d) no hibernation since the previous winter. With fixed frozen sections, the lead salt method of Wachstein and Meisel with adenosine triphosphate as substrate (pH 7.2) showed enzymic activity localized in large vacuoles and smaller vesicles or droplets in the Golgi region of distal and proximal tubular epithelial cells of kidneys from hibernating bats. No ATPase activity was detected in the basal lamellae of tubular epithelium from hibernating bats. ATPase activity in the Golgi region was not seen in cells from kidney tubules of bats aroused from hibernation 24 hours previously or of animals that had not hibernated, whereas activity for ATPase was present in the basal infoldings of tubular epithelium from these animals. Inosine di- and triphosphatase and calcium activated ATPase activities were also detected in the Golgi region of hibernating bats but were not present in the basal infoldings of tubular epithelium from active animals. There was little or no activity toward the mono- and diphosphates of adenine, thiamine pyrophosphate, and the di- or triphosphates of guanidine, cytidine, or deoxyadenosine. The loss of enzymic activity from the Golgi region of the tubular epithelium from hibernating bats and its increase in the region of the basal infoldings of tubular epithelium in aroused bats suggests that the Golgi region plays a role in the synthesis of enzymic protein usually identified with the external cell membrane.

Adenosine Triphosphatases↗
PubMed1997

African bats: evolution of reproductive patterns and delays.

Patterns of reproduction in African bats can be compared in three taxon-based groups: fruit bats (Megachiroptera), freetailed bats (Microchiroptera: Molossidae) and the nonmolossid Microchiroptera. In the fruit bats and nonmolossid Microchiroptera there is a trend from either seasonal or aseasonal polyestry, with prolonged or continuous spermatogenesis in the tropics, towards seasonal monestry and seasonal spermatogenesis at more temperate latitudes. Reproductive delays (sperm storage, delayed implantation and delayed development) are rare at tropical latitudes, but are the norm in the nonmolossid Microchiroptera away from the tropics. The molossids are mostly polyestrous at tropical and temperate latitudes, although the duration of the reproductive season decreases with increasing latitude. The molossids appear to have escaped the constraints that affect reproduction of the other Microchiroptera. We propose that this may be due to their flight capabilities and foraging behavior, which give them access to year-round food, and to the thermal characteristics of their roots. We suggest that the ancestral reproductive pattern of the Chiroptera was probably aseasonal or seasonal polyestry, as seen in extant tropical species, and therefore that reproductive cycles have evolved from the polyestrous to the monestrous condition. Short periods of reproductive delay occur in some species of tropical bats; we suggest that these reproductive delays originally were not adaptations to temperate latitudes but rather to the long dry season, which is characteristic of African tropical latitudes. With the move away from the tropics, selective pressures, acting on the timing of lactation and spermatogenesis, would have ensured that these processes continued to occur in the warm wet season, and that the length of the reproductive delay increased. This model accommodates the probable evolutionary origin of bats and links the evolution and development of reproductive delays to the differences in climate that occur with changes in latitude. There is evidence that mate choice and sperm competition may be important to modern bats, but we believe that they need not be involved as causal factors in the evolution of reproductive delays, which can be adequately explained using purely energetic arguments.

Africa↗
PubMed2003

Dyssochroma viridiflorum (Solanaceae): a reproductively bat-dependent epiphyte from the Atlantic rainforest in Brazil.

Few Neotropical plant species seem to depend on the same animal type both for pollination and seed dispersal, and the known instances refer mostly to birds as the agents in these two phases of a plant reproductive cycle. Dyssochroma viridiflorum (Solanaceae), an epiphyte endemic to the Atlantic rainforest in south-eastern Brazil, was found to be visited by phyllostomid bats for nectar as well as for fruits, with the pollination and seed dispersal of the plant ensured by these flying mammals. The greenish flowers open at night and are visited by the nectar-feeding bat Glossophaga soricina, whereas the yellowish-white fruits are consumed by two species of fruit-eating bats, Carollia perspicillata and Sturnira lilium. Only clinging visits, an uncommon behavioural pattern for glossophagine bats while feeding on flowers, were recorded. The small seeds of D. viridiflorum are swallowed along with the fruit pulp and later defecated on the bats' flying pathways. It is suggested that species of Dyssochroma and two other solanaceous bat-pollinated genera, Merinthopodium and Trianaea, form a derived and bat-dependent clade within the Juanulloeae.

Brazil↗
PubMed2005

A nuclear DNA phylogenetic perspective on the evolution of echolocation and historical biogeography of extant bats (chiroptera).

Bats (Order Chiroptera), the only mammals capable of powered flight and sophisticated laryngeal echolocation, represent one of the most species-rich and ubiquitous orders of mammals. However, phylogenetic relationships within this group are poorly resolved. A robust evolutionary tree of Chiroptera is essential for evaluating the phylogeny of echolocation within Chiroptera, as well as for understanding their biogeographical history. We generated 4 kb of sequence data from portions of four novel nuclear intron markers for multiple representatives of 17 of the 18 recognized extant bat families, as well as the putative bat family Miniopteridae. Three echolocation-call characters were examined by mapping them onto the combined topology: (1) high-duty cycle versus low-duty cycle, (2) high-intensity versus low-intensity call emission, and (3) oral versus nasal emission. Echolocation seems to be highly convergent, and the mapping of echolocation-call design onto our phylogeny does not appear to resolve the question of whether echolocation had a single or two origins. Fossil taxa may also provide insight into the evolution of bats; we therefore evaluate 195 morphological characters in light of our nuclear DNA phylogeny. All but 24 of the morphological characters were found to be homoplasious when mapped onto the supermatrix topology, while the remaining characters provided insufficient information to reconstruct the placement of the fossil bat taxa with respect to extant families. However, a morphological synapomorphy characterizing the Rhinolophoidea was identified and is suggestive of a separate origin of echolocation in this clade. Dispersal-Vicariance analysis together with a relaxed Bayesian clock were used to evaluate possible biogeographic scenarios that could account for the current distribution pattern of extant bat families. Africa was reconstructed as the center of origin of modern-day bat families.

Amino Acid Sequence↗
PubMed2005

Evolutionary timescale of rabies virus adaptation to North American bats inferred from the substitution rate of the nucleoprotein gene.

Throughout North America, rabies virus (RV) is endemic in bats. Distinct RV variants exist that are closely associated with infection of individual host species, such that there is little or no sustained spillover infection away from the primary host. Using Bayesian methodology, nucleotide substitution rates were estimated from alignments of partial nucleoprotein (N) gene sequences of nine distinct bat RV variants from North America. Substitution rates ranged from 2.32 x 10(-4) to 1.38 x 10(-3) substitutions per site per year. A maximum-likelihood (ML) molecular clock model was rejected for only two of the nine datasets. In addition, using sequences from bat RV variants across the Americas, the evolutionary rate for the complete N gene was estimated to be 2.32 x 10(-4). This rate was used to scale trees using Bayesian and ML methods, and the time of the most recent common ancestor for current bat RV variant diversity in the Americas was estimated to be 1660 (range 1267-1782) and 1651 (range 1254-1773), respectively. Our reconstructions suggest that RV variants currently associated with infection of bats from Latin America (Desmodus and Tadarida) share the earliest common ancestor with the progenitor RV. In addition, from the ML tree, times were estimated for the emergence of the three major lineages responsible for bat rabies cases in North America. Adaptation to infection of the colonial bat species analysed (Eptesicus fuscus, Myotis spp.) appears to have occurred much quicker than for the solitary species analysed (Lasionycteris noctivagans, Pipistrellus subflavus, Lasiurus borealis, Lasiurus cinereus), suggesting that the process of virus adaptation may be dependent on host biology.

Adaptation, Biological↗
PubMed1998

Transmission studies of Hendra virus (equine morbillivirus) in fruit bats, horses and cats.

OBJECTIVE: To determine the infectivity and transmissibility of Hendra virus (HeV). DESIGN: A disease transmission study using fruit bats, horses and cats. PROCEDURE: Eight grey-headed fruit bats (Pteropus poliocephalus) were inoculated and housed in contact with three uninfected bats and two uninfected horses. In a second experiment, four horses were inoculated by subcutaneous injection and intranasal inoculation and housed in contact with three uninfected horses and six uninfected cats. In a third experiment, 12 cats were inoculated and housed in contact with three uninfected horses. Two surviving horses were inoculated at the conclusion of the third experiment: the first orally and the second by nasal swabbing. All animals were necropsied and examined by gross and microscopic pathological methods, immunoperoxidase to detect viral antigen in formalin-fixed tissues, virus isolation was attempted on tissues and SNT and ELISA methods were used to detect HeV-specific antibody. RESULTS: Clinical disease was not observed in the fruit bats, although six of eight inoculated bats developed antibody against HeV, and two of six developed vascular lesions which contained viral antigen. The in-contact bats and horses did not seroconvert. Three of four horses that were inoculated developed acute disease, but in-contact horses and cats were not infected. In the third experiment, one of three in-contact horses contracted disease. At the time of necropsy, high titres of HeV were detected in the kidneys of six acutely infected horses, in the urine of four horses and the mouth of two, but not in the nasal cavities or tracheas. CONCLUSIONS: Grey-headed fruit bats seroconvert and develop subclinical disease when inoculated with HeV. Horses can be infected by oronasal routes and can excrete HeV in urine and saliva. It is possible to transmit HeV from cats to horses. Transmission from P poliocephalus to horses could not be proven and neither could transmission from horses to horses or horses to cats. Under the experimental conditions of the study the virus is not highly contagious.

Administration, Intranasal↗
PubMed1969

Echo-location and evoked potentials of bats after ablation of inferior colliculus.

1. Echo-location and evoked potentials of blinded Yuma bats (Myotis yumanensis) were studied before and after ablation of the inferior colliculus (I.C.). A task of obstacle-avoidance was given to the bats: hits and misses of strands in the flight path were counted. Orientation sounds emitted by the bats during flight were recorded.2. Bilateral ablation of the dorso-medial region of I.C. including the internuclear cortex and commissure had no effect on obstacle-avoidance performance. The bats avoided even strands of 0.2 mm diameter with orientation sounds.3. Bilateral ablation of the dorsal half of I.C. including the external nucleus (lateral cortex) also had no effect on echo-location.4. Bilateral ablation of the ventral half of I.C. caused severe deficiency in ability to avoid obstacles. The main nucleus appeared to be very important for echo-location. When bilateral ablation including the main nucleus was moderate, the bats failed to avoid strands of less than 0.5 mm diameter in spite of detecting them, but avoided large obstacles such as 3.7 mm strands. With severe bilateral ablation including the main nucleus, the bats did not avoid even the 3.7 mm strands in spite of frequent emission of orientation sounds, but often avoided crashing into the wall.5. Severe unilateral ablation of I.C. including the main nucleus and a part of the lateral lemniscus had no effect on ability to avoid obstacles. Since sound localization by such bats are not explained by Van Bergeijk's model based on Békésy's, a modification of Van Bergeijk's model has to be considered.6. Of the positive evoked potentials recorded with an active electrode placed at the dorsal surface of I.C., the slow component with a 7-9 msec peak latency reflected activity of inferior collicular neurones, while the fast component (N(4)) with a 3 msec peak latency represented activity of ascending lateral lemniscal fibres.

Animals↗
PubMed2003

The influence of flight speed on the ranging performance of bats using frequency modulated echolocation pulses.

Many species of bat use ultrasonic frequency modulated (FM) pulses to measure the distance to objects by timing the emission and reception of each pulse. Echolocation is mainly used in flight. Since the flight speed of bats often exceeds 1% of the speed of sound, Doppler effects will lead to compression of the time between emission and reception as well as an elevation of the echo frequencies, resulting in a distortion of the perceived range. This paper describes the consequences of these Doppler effects on the ranging performance of bats using different pulse designs. The consequences of Doppler effects on ranging performance described in this paper assume bats to have a very accurate ranging resolution, which is feasible with a filterbank receiver. By modeling two receiver types, it was first established that the effects of Doppler compression are virtually independent of the receiver type. Then, used a cross-correlation model was used to investigate the effect of flight speed on Doppler tolerance and range-Doppler coupling separately. This paper further shows how pulse duration, bandwidth, function type, and harmonics influence Doppler tolerance and range-Doppler coupling. The influence of each signal parameter is illustrated using calls of several bat species. It is argued that range-Doppler coupling is a significant source of error in bat echolocation, and various strategies bats could employ to deal with this problem, including the use of range rate information are discussed.

Acceleration↗
PubMed1997

Echolocation signals of the greater horseshoe bat (Rhinolophus ferrumequinum) in transfer flight and during landing.

Echolocation signals of horseshoe bats (Rhinolophidae) consist of a relatively long component of constant frequency (CF) which is preceded by an initial frequency-modulated (iFM) component and followed by a terminal frequency-modulated (tFM) component. To examine the role of these components in echolocation, four bats were trained to fly from a perch to a landing bar. A dual camera system allowed reconstruction of the flight paths in three dimensions. Echolocation signals were recorded, analyzed, and correlated with the flight behavior of the bats. It was confirmed that during flight the bats compensate the Doppler shifts which are produced by their own flight movement. In free flight they emit per wing beat one single signal of long duration, with little variation in the three signal components. In approach flight the bats reduce pulse duration and interval with decreasing target range. The iFM is not varied with respect to target range, suggesting that this component plays little role in the processing of echolocating a target of interest. The bandwidth of the tFM component is increased while its duration is shortened in proportion to decreasing target range, so that the signal-echo overlap of the FM component is avoided down to a target distance of 15 cm. These concurrent changes suggest that the tFM component is used for ranging. During the last 60 cm of the approach the bats compensated for the increase of echo SPL by lowering the emission level of the CF component by 6-9 dB and that of the tFM component by 9-11 dB per halving of range. The specific signal structure of horseshoe bats is discussed as an adaptation for the hunting of fluttering insects in highly cluttered environments.

Animals↗