Auditory sensitivity and frequency selectivity in greater spear-nosed bats suggest specializations for acoustic communication

We investigated the relationship between auditory sensitivity, frequency selectivity, and the vocal repertoire of greater spear-nosed bats (Phyllostomus hastatus). P. hastatus commonly emit three types of vocalizations: group-specific foraging calls that range from 6 to 11 kHz, low amplitude echolocation calls that sweep from 80 to 40 kHz, and infant isolation calls from 15 to 100 kHz. To determine if hearing in P. hastatus is differentially sensitive or selective to frequencies in these calls, we determined absolute thresholds and masked thresholds using an operant conditioning procedure. Both absolute and masked thresholds were lowest at 15 kHz, which corresponds with the peak energy of isolation calls. Auditory and masked thresholds were higher at sound frequencies used for group-specific foraging calls and echolocation calls. Isolation calls meet the requirements of individual signatures and facilitate parent-offspring recognition. Many bat species produce isolation calls with peak energy between 10 and 25 kHz, which corresponds with the frequency region of highest sensitivity in those species for which audiogram data are available. These findings suggest that selection for accurate offspring recognition exerts a strong influence on the sensory system of P. hastatus and likely on other species of group-living bats.     

Social calls are subject to stabilizing selection in insular bats

Aim Bats communicate by emitting social calls, and these often elicit reactions in conspecifics. Many such vocalizations are species‐specific so that unambiguous signals can be transmitted and interpreted by conspecifics. In species‐rich assemblages, evolutionary pressures might prompt interspecific diversification of call structure so that communication with heterospecifics is avoided. In species‐poor island communities, where no risk of miscommunication occurs, stabilizing selection should prevail and preserve call structure and function. Call structure in island bats might be inherited from colonizers from the mainland and be maintained with little change in the absence of selection from heterospecifics. To test this hypothesis we studied Pipistrellus maderensis, an insular taxon occurring on the Madeira Archipelago, the Canary Islands and the Azores. It is closely related to one of the most widespread European pipistrelles, Pipistrellus kuhlii. Pipistrellus maderensis most probably evolved from a common ancestor shared with P. kuhlii, or from founders of that taxon that colonized the islands. We hypothesized that on Madeira Island, where no risk of ambiguous communication with heterospecifics exists, the structure and function of social calls should have been preserved by stabilizing selection. Echolocation calls, subject to different selection pressures, may instead show more pronounced differences between P. maderensis and P. kuhlii. Location Madeira Island (Portugal, Atlantic Ocean), central and southern Italy. Methods We recorded social and echolocation calls from allopatric populations of the two pipistrelles and explored interspecific differences in time and frequency characteristics. We also conducted playback experiments by broadcasting recordings of social calls from P. kuhlii and P. maderensis (taken respectively in peninsular Italy and on Madeira) and monitoring the bats’ responses. Results Social call structure showed a strong similarity between species, whereas echolocation calls were markedly different and exhibited a mean divergence of over 6 kHz in their frequency of maximum energy. On Madeira, P. maderensis significantly reduced flight activity when we broadcast P. kuhlii signals, as did P. kuhlii in Italy in response to P. maderensis calls. Main conclusions Reliable interpretation of social calls provides benefits to both the signaller and the receiver because signals help to optimize food exploitation at foraging sites. In the absence of closely related species that can emit similar calls, this advantage may have acted as a strong evolutionary pressure, stabilizing social call structure in P. maderensis in insular ecosystems with limited foraging resources.     

Selective Eavesdropping Behaviour in Three Neotropical Bat Species

Knowledge of interspecies information transfer in mammals is scarce compared with other taxa. We investigated whether eavesdropping on echolocation calls of bats may be used by sympatric bats with similar feeding ecology. We performed playback experiments with three free‐ranging neotropical bat species, broadcasting search phase calls or feeding buzzes of conspecifics and heterospecifics belonging either to the same or to another bat family. Both the greater fishing bat Noctilio leporinus and the lesser bulldog bat Noctilio albiventris (Noctilionidae) reacted with repeated approaches in response to playbacks of search phase calls and feeding buzzes from conspecifics and also to congeneric feeding buzzes. Noctilio leporinus also were attracted by search phase calls from its sister species N. albiventris. In contrast, the sac‐winged bat Saccopteryx bilineata (Emballonuridae) did not react to any playback sequences presented. Our results support the existence of eavesdropping behaviour for both species of Noctilio. We suggest that information transfer via eavesdropping may depend mainly on species‐specific traits, including foraging style and social behaviour (territoriality, group foraging), and on distribution and density of prey. Call design had only a minor influence on the reaction.     

Plasticity in echolocation calls of <Emphasis Type="Italic">Myotis macrodactylus</Emphasis> (Chiroptera: Vespertilionidae): implications for acoustic identification

Poor knowledge of the intraspecific variability in echolocation calls is recognized as an important limiting factor for the accurate acoustic identification of bats. We studied the echolocation behaviors of an ecologically poorly known bat species, Myotis macrodactylus, while they were commuting in three types of habitats differing significantly in the amount of background clutter, as well as searching for prey above the water surface in a river. Results showed that M. macrodactylus altered their echolocation call structure in the same way during commuting as foraging bats do in relation to the changing level of clutter. With increasing level of clutter, M. macrodactylus generally produced echolocation calls with higher start, end, and peak frequencies; wider bandwidth; and shorter pulse duration. Compared to commuting, bats emitted significantly lower frequency calls with narrower bandwidth while searching for prey. Discriminant function analysis indicated that 79.8% of the calls from the three commuting habitats were correctly grouped, and 87% of the calls were correctly classified to the commuting and foraging contexts. Our finding has implications for those who would identify species by their calls.     

Eavesdropping by Bats: The Influence of Echolocation Call Design and Foraging Strategy

We used playback presentations to free-flying bats of 3 species to assess the influence of echolocation call design and foraging strategy on the role of echolocation calls in communication. Near feeding sites over water, Myotis lucifugus and M. yumanensis responded positively only to echolocation calls of conspecifics. Near roosts, these bats did not respond before young of the year became volant, and after this responded to presentations of echolocation calls of similar and dissimilar design. At feeding sites Lasiurus borealis responded only to echolocation calls of conspecifics and particularly to “feeding buzzes”. While Myotis, particularly subadults, appear to use the echolocation calls of conspecifics to locate feeding sites, L. borealis appears to use the calls of a foraging neighbour attacking prey to identify opportunities for ‘stealing’ food.     

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.     

Driving Factors for the Evolution of Species-Specific Echolocation Call Design in New World Free-Tailed Bats (Molossidae)

Phylogeny, ecology, and sensorial constraints are thought to be the most important factors influencing echolocation call design in bats. The Molossidae is a diverse bat family with a majority of species restricted to tropical and subtropical regions. Most molossids are specialized to forage for insects in open space, and thus share similar navigational challenges. We use an unprecedented dataset on the echolocation calls of 8 genera and 18 species of New World molossids to explore how habitat, phylogenetic relatedness, body mass, and prey perception contribute to echolocation call design. Our results confirm that, with the exception of the genus Molossops, echolocation calls of these bats show a typical design for open space foraging. Two lines of evidence point to echolocation call structure of molossids reflecting phylogenetic relatedness. First, such structure is significantly more similar within than among genera. Second, except for allometric scaling, such structure is nearly the same in congeneric species. Despite contrasting body masses, 12 of 18 species call within a relatively narrow frequency range of 20 to 35 kHz, a finding that we explain by using a modeling approach whose results suggest this frequency range to be an adaptation optimizing prey perception in open space. To conclude, we argue that the high variability in echolocation call design of molossids is an advanced evolutionary trait allowing the flexible adjustment of echolocation systems to various sensorial challenges, while conserving sender identity for social communication. Unraveling evolutionary drivers for echolocation call design in bats has so far been hampered by the lack of adequate model organisms sharing a phylogenetic origin and facing similar sensorial challenges. We thus believe that knowledge of the echolocation call diversity of New World molossid bats may prove to be landmark to understand the evolution and functionality of species-specific signal design in bats.     

Bat echolocation calls facilitate social communication

Bat echolocation is primarily used for orientation and foraging but also holds great potential for social communication. The communicative function of echolocation calls is still largely unstudied, especially in the wild. Eavesdropping on vocal signatures encoding social information in echolocation calls has not, to our knowledge, been studied in free-living bats so far. We analysed echolocation calls of the polygynous bat Saccopteryx bilineata and found pronounced vocal signatures encoding sex and individual identity. We showed experimentally that free-living males discriminate approaching male and female conspecifics solely based on their echolocation calls. Males always produced aggressive vocalizations when hearing male echolocation calls and courtship vocalizations when hearing female echolocation calls; hence, they responded with complex social vocalizations in the appropriate social context. Our study demonstrates that social information encoded in bat echolocation calls plays a crucial and hitherto underestimated role for eavesdropping conspecifics and thus facilitates social communication in a highly mobile nocturnal mammal.     

Substrate-gleaning versus aerial-hawking: plasticity in the foraging and echolocation behaviour of the long-eared bat,Myotis evotis

The foraging and echolocation behaviour of Myotis evotis was investigated during substrate-gleaning and aerial-hawking attacks. Bats gleaned moths from both the ground and a bark-covered trellis, however, they were equally adept at capturing flying moths. The calls emitted by M. evotis during substrate-gleaning sequences were short, broadband, and frequency-modulated (FM). Three behavioural phases were identified: search, hover, and attack. Gleaning search calls were significantly longer in duration, lower in highest frequency, and larger in bandwidth than hover/attack calls. Calls were detected in only 68% of gleaning sequences, and when they were emitted, bats ceased calling 200 ms before attacking. Terminal feeding buzzes, the rapid increase in pulse repetition rate associated with an attempted prey capture, were never recorded during gleaning attacks. The echolocation calls uttered by M. evotis during aerial-hawking foraging sequences were also short duration, high frequency, FM calls. Two distinct acoustic phases were identified: approach and terminal. Approach calls were significantly different from terminal calls in all variables measured. Calls were detected in 100% of aerial-hawking attacks and terminal feeding buzzes were invariably produced. Gleaning hover/attack calls were spectrally similar to aerial approach calls, but were shorter in duration and emitted at a significantly lower (but constant) repetition rate than aerial signals. Although the foraging environment (flight cage contents) remained unchanged between tasks (substrate-gleaning vs. aerial-hawking), bats emitted significantly lower amplitude calls while gleaning. We conclude that M. evotis adjusts its echolocation behaviour to meet the perceptual demands (acoustical constraints) imposed by each foraging situations.Abbreviations BW bandwidth - CF constant frequency - dB SPL decibels sound pressure level - FM frequency modulated - HF highest frequency - LF lowest frequency - PF peak frequency Presented at the meeting Acoustic Images in Bat Sonar, a conference on FM echolocation honoring Donald R. Griffin's contributions to experimental biology (June 14–16, Brown University, Providence RI).     

Echolocation calls produced by Kuhl's pipistrelles in different flight situations

Flexibility in the echolocation call structure of bats can improve their performances, because, in some situations, some signal designs are better than others. Hence, at least some bats should adjust their echolocation calls according to the setting in which they are operating but also to the specific task at hand, that is their behavioral intention. We studied variation in the echolocation calls of Pipistrellus kuhlii emitted during four flight situations that were similar in setting but differed in behavioral context: emergence from a roost, commuting to and from foraging sites, foraging and returning to a roost. Echolocation calls produced by P. kuhlii differed significantly according to the flight situation. Call types differed most distinctly between foraging and commuting. We also found a high variance in the emergence calls we recorded, perhaps reflecting pre- and post-takeoff calls. Discriminant function analysis on calls emitted while foraging, commuting or returning to the roost classified the calls to the correct group 73.3% of the time. The differences between bats' echolocation calls in different flight situations might indicate an intrinsic change in the bat's behavior. Recognizing these differences could be crucial when using call variables to identify bat species.     

The tiny difference between foraging and communication buzzes uttered by the Mexican free-tailed bat, <Emphasis Type="Italic">Tadarida brasiliensis</Emphasis>

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.     

Sound-evoked oscillation and paradoxical latency shift in the inferior colliculus neurons of the big fruit-eating bat, <Emphasis Type="Italic">Artibeus jamaicensis</Emphasis>

Frequency tuning, temporal response pattern and latency properties of inferior colliculus neurons were investigated in the big fruit-eating bat, Artibeus jamaicensis. Neurons having best frequencies between 48–72 kHz and between 24–32 kHz are overrepresented. The inferior colliculus neurons had either phasic (consisting in only one response cycle at all stimulus intensities) or long-lasting oscillatory responses (consisting of multiple response cycles). Seventeen percent of neurons displayed paradoxical latency shift, i.e. their response latency increased with increasing sound level. Three types of paradoxical latency shift were found: (1) stable, that does not depend on sound duration, (2) duration-dependent, that grows with increasing sound duration, and (3) progressive, whose magnitude increases with increasing sound level. The temporal properties of paradoxical latency shift neurons compare well with those of neurons having long-lasting oscillatory responses, i.e. median inter-spike intervals and paradoxical latency shift below 6 ms are overrepresented. In addition, oscillatory and paradoxical latency shift neurons behave similarly when tested with tones of different durations. Temporal properties of oscillation and PLS found in the IC of fruit-eating bats are similar to those found in the IC of insectivorous bats using downward frequency-modulated echolocation calls.     

Does body mass restrict call peak frequency in echolocating bats?

1. Echolocation is the ability of some animals to orient themselves through sound emission and interpretation of the echoes. This is bats’ main sense for orientation and recognising biotopes that provide food, water, and roosts. It is widely accepted that echolocation call frequency is related to body mass, and this relationship has been described as the ‘allometric hypothesis’, which proposes a negative correlation between these variables.
2. There is evidence that, in many cases, the allometric hypothesis does not apply. Additionally, studies supporting this hypothesis were done at the family level, resulting in a broad range of correlation values with r ranging from −0.36 to −0.76, and only insectivorous bats were included. Due to the notable exceptions and the lack of a quantitative synthesis of this hypothesis including all echolocating bats, we evaluated the allometric hypothesis of echolocation calls for this group.
3. Using a meta-analysis and phylogenetic generalised least-squares techniques, we evaluated the relationship between echolocation call peak frequency and the body mass of bats.
4. We found a negative relationship between body mass and echolocation call peak frequency for the 85 bat species that were included in our analysis (r = −0.3, p = 0.005). The relationship was consistent when we analysed the data at the insectivorous guild level, and in bats belonging to the families Vespertilionidae, Rhinolophidae, Emballonuridae, and the genus Myotis. However, the wide range of r values suggests that the strength of the relationship between peak frequency and body mass varies within the order Chiroptera.
5. Our results support the allometric hypothesis of sound production in echolocating bats. However, the low coefficient we found suggests that factors other than body mass may influence the peak frequency of echolocation calls produced by bats.

     

Gleaning bat echolocation calls do not elicit antipredator behaviour in the Pacific field cricket, <Emphasis Type="Italic">Teleogryllus oceanicus</Emphasis> (Orthoptera: Gryllidae)

Bats that glean prey (capture them from surfaces) produce relatively inconspicuous echolocation calls compared to aerially foraging bats and could therefore be difficult predators to detect, even for insects with ultrasound sensitive ears. In the cricket Teleogryllus oceanicus, an auditory interneuron (AN2) responsive to ultrasound is known to elicit turning behaviour, but only when the cricket is in flight. Turning would not save a cricket from a gleaning bat so we tested the hypothesis that AN2 elicits more appropriate antipredator behaviours when crickets are on the ground. The echolocation calls of Nyctophilus geoffroyi, a sympatric gleaning bat, were broadcast to singing male and walking female T. oceanicus. Males did not cease singing and females did not pause walking more than usual in response to the bat calls up to intensities of 82 dB peSPL. Extracellular recordings from the cervical connective revealed that the echolocation calls elicited AN2 action potentials at high firing rates, indicating that the crickets could hear these stimuli. AN2 appears to elicit antipredator behaviour only in flight, and we discuss possible reasons for this context-dependent function.     

Flight performance, echolocation and foraging behaviour in noctule bats Nyctalus noctula

The noctule Nyctulus noctula (Schreber, 1774) is a relatively large (c. 25 g) insectivorous bat which catches insects on the wing (by aerial hawking). Emergence at a maternity roost was earliest relative to sunset when females were lactating, and bats may then have risked predation by flying at higher light levels during a period of high energy demand. Flight performance was quantified by using stereophotogrammetry. At feeding sites bats flew at 6.0 ± 2.1 m/s. This was faster than predicted minimum power speed (V _mp), and either between V _mp and maximum range speed (V _mr), or close to their predicted V _mr, depending on which aerodynamic model of flight power requirements was used. The echolocation behaviour of noctules is flexible. Long duration, low frequency calls (c. 20 kHz) with little frequency modulation were emitted while cruising, but at foraging sites the calls became more frequency-modulated. As the noctule is traditionally thought of as using low frequency echolocation, it was expected to receive weak echoes from small targets and therefore to specialize in eating large insect prey. Although the bats ate mainly beetles, large numbers of small dipterans were also eaten. The noctule is probably able to detect such small items because, when foraging, its calls become broadband and sweep from high frequencies. Higher harmonics are also present, and these may assist in the detection of small prey. In noctules, as in many bats, there appears to be a 1:1 link between wingbeat and call production during the search phase of foraging.     

Echolocation range and wingbeat period match in aerial-hawking bats

Aerial-hawking bats searching the sky for prey face the problem that flight and echolocation exert independent and possibly conflicting influences on call intervals. These bats can only exploit their full echolocation range unambiguously if they emit their next call when all echoes from the preceding call would have arrived. However, not every call interval is equally available. The need to reduce the high energetic costs of echolocation forces aerial-hawking bats to couple call emission to their wingbeat. We compared the wingbeat periods of 11 aerial-hawking bat species with the delays of the last-expected echoes. Acoustic flight-path tracking was employed to measure the source levels (SLs) of echolocation calls in the field. SLs were very high, extending the known range to 133 dB peak equivalent sound pressure level. We calculated the maximum detection distances for insects, larger flying objects and background targets. Wingbeat periods were derived from call intervals. Small and medium-sized bats in fact matched their maximum detection range for insects and larger flying targets to their wingbeat period. The tendency to skip calls correlated with the species' detection range for background targets. We argue that a species' call frequency is at such a pitch that the resulting detection range matches their wingbeat period.     

Echolocation behaviours of the Japanese pipistrelle batPipistrellus abramus during foraging flight

The acoustic structure of echolocation pulses emitted by Japanese pipistrellePipistrellus abramus (Temminck, 1840) bats during different phases of aerial hawking is described here for the first time. Behavioural observations of the foraging flight in conjunction with acoustical analysis of echolocation pulses indicated a flight path consisting of four distinct phases following the reconnaissance or search phase. Short (∼4.68 ms) and relatively broadband frequencymodulated (FM) pulses (∼23.55 kHz bandwidth) were emitted at a repetition rate of 15 Hz during presumed target approach. Presumed insect capture consisted of an early and a late buzz phase. Both buzz types were emitted at high repetition rates (111 Hz in early to 222 Hz in late) and consisted of very short, broadband FM pulses (1.26 ms in early to 0.3 ms in late). There was also a characteristically sharp drop in both the peak and terminal frequencies of each echolocation pulse during the transition from early to late buzz. No pulses were recorded during the final phase of foraging referred to as a “post-buzz pause”. Thus the foraging behaviour of this species consisted of five sequential phases involving four broad types of echolocation pulses.     

Functional differences in echolocation call design in an adaptive radiation of bats

All organisms have specialized systems to sense their environment. Most bat species use echolocation for navigation and foraging, but which and how ecological factors shaped echolocation call diversity remains unclear for the most diverse clades, including the adaptive radiation of neotropical leaf‐nosed bats (Phyllostomidae). This is because phyllostomids emit low‐intensity echolocation calls and many inhabit dense forests, leading to low representation in acoustic surveys. We present a field‐collected, echolocation call dataset spanning 35 species and all phyllostomid dietary guilds. We analyze these data under a phylogenetic framework to test the hypothesis that echolocation call design and parameters are specialized for the acoustic demands of different diets, and investigate the contributions of phylogeny and body size to echolocation call diversity. We further link call parameters to dietary ecology by contrasting minimum detectable prey size estimates (MDPSE) across species. We find phylogeny and body size explain a substantial proportion of echolocation call parameter diversity, but most species can be correctly assigned to taxonomic (61%) or functional (77%) dietary guilds based on call parameters. This suggests a degree of acoustic ecological specialization, albeit with interspecific similarities in call structure. Theoretical MDPSE are greatest for omnivores and smallest for insectivores. Omnivores significantly differ from other dietary guilds in MDPSE when phylogeny is not considered, but there are no differences among taxonomic dietary guilds within a phylogenetic context. Similarly, predators of non‐mobile/non‐evasive prey and predators of mobile/evasive prey differ in estimated MDPSE when phylogeny is not considered. Phyllostomid echolocation call structure may be primarily specialized for overcoming acoustic challenges of foraging in dense habitats, and then secondarily specialized for the detection of food items according to functional dietary guilds. Our results give insight into the possible ecological mechanisms shaping the diversity of sensory systems, and their reciprocal influence on resource use.     

皮氏菊头蝠回声定位声波与年龄的关系

皮氏菊头蝠 (Rhinolophuspearsoni)雌性成体 5只和幼体 2只采自贵州省贞丰县珉谷镇。采用超声波探测仪 (D980 ,ULTRASOUNDDETECTOR)接收皮氏菊头蝠的回声定位声波 ,转换到原频率的 1 / 1 0后导入计算机 ,然后用专业声谱分析软件 (Batsound 3 1 0 )进行分析。成蝠在飞行和悬挂状态下的声波结构相似 ,只是声波各项参数值略有不同 :它们发射FM CF FM型声波 ,具有 2～ 3个谐波 ,主频率在飞行时为 5 6 80± 0 6 2kHz ,悬挂时为 5 8 0 5± 0 2 4kHz ;声脉冲时间和间隔在飞行时分别为 3 4 6 2± 5 2 9ms和 86 5 0± 1 9 72ms ,悬挂时分别为 4 1 0 8± 5 87ms和 1 1 7 2 9± 6 6 4 4ms ;能率环飞行时为 ( 4 4 0 6± 1 2 5 8) % ,悬挂时为 ( 4 6 0 0±2 4 2 5 ) %。幼蝠声波为CF FM型 ,谐波数为 5～ 8个 ,主频率明显低于成体 ,FM带宽窄于成体 ,声脉冲时间和间隔短于成体 ,能率环低于成体。皮氏菊头蝠回声定位声波与年龄有关 ,这可能因成体的声波主要是探测食物和周围环境的详细信息 ,而幼体主要是与母蝠进行交流。