Collicular evoked potentials in Rhinolophus ferrum equinum show very prominent responses to the final frequency modulated part of a acoustic stimulus, simulating the natural echolocation sound.

Bat Ecology replaces ‘the Kunz’, the first book on bat ecology published in 1982 [ 1 Kunz T.H Ecology of Bats. Plenum Press, 1982 Crossref Google Scholar ]. For 20 years, this treatise, edited by Thomas H. Kunz, was the reference book and introductory reading for what was then a small group of investigators studying bats in all types of biotope, from tropical forests to townships and deserts. This new book demonstrates the enormous progress and increase in quantitative ecological investigations that result from the growing interest of students in studying bats, and the computerized methods, remote-sensing and data-collecting devices that have revolutionized quantitative field research over the past two decades.

This review is yet another attempt to explain how echolocation in bats or bat-like mammals came into existence. Attention is focused on neuronal specializations in the ascending auditory pathway of echolocating bats. Three different mechanisms are considered that may create a specific auditory sensitivity to echos: (1). time-windows of enhanced echo-processing opened by a corollary discharge of neuronal vocalization commands; (2). differentiation and expansion of ensembles of combination-sensitive neurons in the midbrain; and (3). corticofugal top-down modulations. The second part of the review interprets three different types of echolocation as adaptations to ecological niches, and presents the sophisticated cochlear specializations in constant-frequency/frequency-modulated bats as a case study of finely tuned differentiation. It is briefly discussed how a resonant mechanism in the inner ear of constant-frequency/frequency-modulated bats may have evolved in common mammalian cochlea.

Although bats are nocturnal, many species emerge from roosts to forage during twilight, despite a presumed high risk of predation at this time. Here, we describe twilight foraging by a maternity colony of Schneider's leafnosed bat (Hipposideros speoris) in the dry zone of Sri Lanka and determine the dietary benefits of such behavior. Bats usually began foraging during dusk, sometimes before sunset, and also foraged during twilight in the morning. Mean use of available twilight by four radio-tagged bats was 75 percent. Twilight foraging made up, on average, 47 percent of the total foraging time of these bats (range = 25–96%), although twilight consisted of only 12 percent of the available time between sunset and sunrise the next morning. Eight species of potential predators (7 birds and 1 mammal) were observed within a 1 km radius of the colony, of which 5 species are predicted to regularly capture bats. Bats took a wide diversity of prey (11 insect orders, including at least 27 families, and spiders) that ranged in wing length from 2.0 to 54.0 mm. Major orders in the diet were Coleoptera, Lepidoptera, and Diptera. Prey of secondary importance included Hemiptera, Hymenoptera, Isoptera, and Neuroptera. Bats captured large numbers of insects that were only available or had marked peaks in abundance during twilight. These groups included small, swarming insects (especially flies) that have peaks in flight activity at dusk and dawn, large diurnal species (especially dragonflies) that have crepuscular activity, and winged termites that emerge in swarms at dusk. Access to these insects was a clear benefit of twilight foraging.

Abstract A total of 101 animals were sampled from three nursery colonies of Myotis myotis in Portugal and in Bavaria, southern Germany. A segment of the triple-stranded part of the mitochondrial control region ranging from 400 bp to 800 bp was amplified via PCR and analysed by gel electrophoresis. Substantial length variation was found among different animals and 33% of the bats were heteroplasmic for up to six different size classes. When the DNA sequence of the heteroplasmic segment was determined, the length variation was found to be due to a variable number of tandemly repeated motifs of 82 bp, as has also been described for the American evening bat, Nycticeius humeralis. Heteroplasmy, as well as homoplasmy, were stably inherited in 25 mother-pup pairs. Mechanisms for the generation of length and sequence heteroplasmy are thought to be slippage mutations caused by the D-loop replication procedures and to a lesser degree by biparental inheritance of mitochondrial DNA.

In bat audition, major advances have been made concerning the frequency tuning in the bats' cochlea, cortical maps and the related subcortical echo information processing, and the perceptual mechanisms creating auditory images.

Within the tonotopic organization of the inferior colliculus two frequency ranges are well represented: a frequency range within that of the echolocation signals from 50 to 100 kHz, and a frequency band below that of the echolocation sounds, from 10 to 35 kHz. The frequency range between these two bands, from about 40 to 50 kHz is distinctly underrepresented (Fig. 3B).

Field observations in a maternity colony of Myotis emarginatus (Vespertilionidae) were made during the summers of 1986 and 1987 in southern Germany. The nursery colony consisted of about 90 adult and 30 juvenile bats which roosted in a dimly lit and relatively cool church attic. Telemetry data from six adult M. emarginatus disclosed that some individuals also use secondary day roosts in trees or small buildings located close to their foraging areas. During the night, radiotagged individuals spent most of the time on the wing in forested areas (Fig. 2). Stationary bouts lasted no longer than 63 min. Individual bats returned to the same foraging areas on consecutive nights. All major foraging areas were situated in or at the fringes of forests, at distances as far as 10 km from the nursery roost. During commuting flights to the forests, M. emarginatus avoided open fields and preferred flight paths which offered cover such as orchards, hedges, overhanging foliage along creeks, etc. On the way to the forests, the bats started to forage within buildings, in open spaces where aggregations of insects were present, and around or within the foliage of various types of trees at the level of tree tops or the upper third of the foliage. At these transient foraging areas close to the maternity roost, M. emarginatus displayed flexible foraging strategies: (1) They gleaned prey (mainly flies and spiders) from the substrate, (2) seized insects in aerial pursuit, and (3) occasionally hovered in front of foliage and walls.

In Myotis emarginatus, the patterns of echolocation sounds vary with different foraging habitats: In commuting flights the echolocation sounds are linearly frequency modulated sweeps that start at about 100 kHz, terminate at 40 kHz, and have a duration of 1–3 ms. They consist of a loud first harmonic. The second and third harmonics are at least 15 dB fainter than the first one and often undetectable. A distinctly different type of sound is emitted when the bats search for flying insects in open spaces. The sounds are reduced in bandwidth and elongated by a constant frequency component that follows the initial frequency modulated part. Typically, sounds start at about 94 kHz and terminate in a constant frequency component at about 40–45 kHz. The average duration of the constant frequency tail is 2.8 ms; this approximately doubles the length of the pulse, with the longest recorded sound lasting 7.2 ms. When bats are foraging near and within foliage, and gleaning prey from foliage, echolocation sounds are brief (average 1 ms) frequency modulated pulses with a broad bandwidth. The pulses start at about 105 kHz and sweep down to 25 kHz. During gleaning within a building, the frequency range of the sounds is shifted to higher frequencies and extends from 124 to 52 kHz. When the bats forage for aireal insects in a confined area that creates echo-clutter, they emit sounds similar to those used during gleaning within buildings except that sound durations are extended to about 1.8 ms. In each foraging area, the echolocation sounds emitted during the search for and approach to prey are similar in structure. Sound and pause durations are reduced in the approach phase. Irrespective of foraging style and habitat, immediately before capture the bat emits a rapid and stereotyped sequence of 2-10 echolocation pulses (final buzz). These pulses are brief (0.2–0.5 ms), frequency modulated sounds with a reduced bandwidth. The sounds start at 45 kHz and sweep down to 35–20 kHz. The repetition rate is increased up to 200 pulses/s.

articleAuditory adaptations for prey capture in echolocating batsG. NeuweilerG. NeuweilerZoologisches Institut, Universitat Munchen, Federal Republic ofGermany.Published Online:01 Jul 1990https://doi.org/10.1152/physrev.1990.70.3.615MoreSectionsPDF (8 MB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformation Cited ByRobustness of cortical and subcortical processing in the presence of natural masking sounds1 May 2018 | Scientific Reports, Vol. 8, No. 1Echolocation and flight behavior of the bat Hipposideros armiger terasensis in a structured corridorThe Journal of the Acoustical Society of America, Vol. 144, No. 2In-flight social calls: a primer for biologists and managers studying echolocationCanadian Journal of Zoology, Vol. 96, No. 8It’s not all about the Soprano: Rhinolophid bats use multiple acoustic components in echolocation pulses to discriminate between conspecifics and heterospecifics18 July 2018 | PLOS ONE, Vol. 13, No. 7Brazilian free-tailed bats ( Tadarida brasiliensis ) adjust foraging behaviour in response to migratory mothsCanadian Journal of Zoology, Vol. 96, No. 6Specialization of the auditory system for the processing of bio-sonar information in the frequency domain: Mustached batsHearing Research, Vol. 361Don’t believe the mike: behavioural, directional, and environmental impacts on recorded bat echolocation call measuresCanadian Journal of Zoology, Vol. 96, No. 4Illuminating prey selection in an insectivorous bat community exposed to artificial light at night29 November 2017 | Journal of Applied Ecology, Vol. 55, No. 2Bats are still not birds in the digital era: echolocation call variation and why it matters for bat species identificationCanadian Journal of Zoology, Vol. 96, No. 2The organization of melanopsin-immunoreactive cells in microbat retina5 January 2018 | PLOS ONE, Vol. 13, No. 1Bat Neuroethology ☆Adaptations for Substrate Gleaning in Bats: The Pallid Bat as a Case Study6 June 2018 | Brain, Behavior and Evolution, Vol. 91, No. 2Echolocating bats rely on audiovocal feedback to adapt sonar signal design25 September 2017 | Proceedings of the National Academy of Sciences, Vol. 114, No. 41Stereotypy of group flight in Brazilian free-tailed batsAnimal Behaviour, Vol. 131To seek or speak? Dual function of an acoustic signal limits its versatility in communicationAnimal Behaviour, Vol. 127Evolutionary escalation: the bat–moth arms race1 June 2016 | The Journal of Experimental Biology, Vol. 219, No. 11Big brown bats ( Eptesicus fuscus ) emit intense search calls and fly in stereotyped flight paths as they forage in the wild23 November 2015 | The Journal of Experimental Biology, Vol. 219, No. 3Decoding stimulus duration from neural responses in the auditory midbrainBrandon Aubie, Riziq Sayegh, Thane Fremouw, Ellen Covey, and Paul A. Faure15 November 2014 | Journal of Neurophysiology, Vol. 112, No. 10Shifted encoding strategy in retinal luminance adaptation: from firing rate to neural correlationLei Xiao, Mingsha Zhang, Dajun Xing, Pei-Ji Liang*, and Si Wu*15 October 2013 | Journal of Neurophysiology, Vol. 110, No. 8Duration tuning in the inferior colliculus of the mustached batSilvio Macías, Emanuel C. Mora, Julio C. Hechavarría, and Manfred Kössl1 December 2011 | Journal of Neurophysiology, Vol. 106, No. 6Behavioral Evidence for Community‐Wide Species Discrimination from Echolocation Calls in BatsThe American Naturalist, Vol. 176, No. 1Duration-Sensitive Neurons in the Inferior Colliculus of Horseshoe Bats: Adaptations for Using CF-FM Echolocation PulsesFeng Luo, Walter Metzner, Feijian J. Wu, Shuyi Y. Zhang*, and Qicai C. Chen*1 January 2008 | Journal of Neurophysiology, Vol. 99, No. 1A Comparative Analysis of Specialization and Extinction Risk in Temperate-Zone BatsConservation Biology, Vol. 18, No. 5Echolocation signals reflect niche differentiation in five sympatric congeneric bat species10 June 2004 | Nature, Vol. 429, No. 6992Ambiguities in Sound-Duration Selectivity by Neurons in the Inferior Colliculus of the Bat Molossus molossus From CubaEmanuel C. Mora, and Manfred Kössl1 May 2004 | Journal of Neurophysiology, Vol. 91, No. 5Neural Processing of Amplitude-Modulated SoundsP. X. JORIS, C. E. SCHREINER, and A. REES1 April 2004 | Physiological Reviews, Vol. 84, No. 2Neurobiology of echolocation in batsCurrent Opinion in Neurobiology, Vol. 13, No. 6Development of Echolocation Calls in the Mustached Bat, Pteronotus parnelliiM. Vater, M. Kössl, E. Foeller, F. Coro, E. Mora, and I. J. 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Casseday1 November 2001 | Journal of Neurophysiology, Vol. 86, No. 5PHYLOGENETIC RELATIONSHIPS OF MORMOOPID BATS (CHIROPTERA: MORMOOPIDAE) BASED ON MORPHOLOGICAL DATABulletin of the American Museum of Natural History, Vol. 258, No. 1Neural Measurement of Sound Duration: Control by Excitatory-Inhibitory Interactions in the Inferior ColliculusJohn H. Casseday, Daphna Ehrlich, and Ellen Covey1 September 2000 | Journal of Neurophysiology, Vol. 84, No. 3Micromechanical Responses to Tones in the Auditory Fovea of the Greater Mustached Bat’s CochleaI. J. Russell, and M. Kössl1 August 1999 | Journal of Neurophysiology, Vol. 82, No. 2The postnatal development of frequency-place code and tuning characteristics in the auditory midbrain of the phyllostomid bat, Carollia perspicillataHearing Research, Vol. 76, No. 1-2Otoacoustic emissions from the cochlea of the ‘constant frequency’ bats, Pteronotus parnellii and Rhinolophus rouxiHearing Research, Vol. 72, No. 1-2Audition in echolocating batsCurrent Opinion in Neurobiology, Vol. 3, No. 4Psychophysical frequency modulation thresholds in a FM-bat, Tadarida brasiliensisHearing Research, Vol. 67, No. 1-2The organ of Corti in the bat Hipposideros bicolorHearing Research, Vol. 53, No. 2Computational representations of sonar images in batsCurrent Biology, Vol. 1, No. 3Audition in vampire bats, Desmodus rotundusJournal of Comparative Physiology A, Vol. 168, No. 1 More from this issue > Volume 70Issue 3July 1990Pages 615-641 Copyright & PermissionsCopyright © 1990 the American Physiological Societyhttps://doi.org/10.1152/physrev.1990.70.3.615PubMed2194220History Published online 1 July 1990 Published in print 1 July 1990 Metrics

The postnatal development of midbrain tonotopy was investigated in the inferior colliculus (IC) of the south Indian CF-FM batHipposideros speoris. The developmental progress of the three-dimensional frequency representation was determined by systematic stereotaxic recordings of multiunit clusters from the 1st up to the 7th postnatal week. Additional developmental measures included the tuning characteristics of single units (Figs. 3f; 4f; 5f), the analysis of the vocalised pulse repertoire (Figs. 3e, 4e, 5e), and morphometric reconstructions of the brains of all experimental animals (Fig. 1).

The diets of Rhinolophus rouxi and Hipposideros lankadiva were studied during October 1984 in Sri Lanka, by analysing the faeces collected from individuals. As a comparison, insects were collected with a light trap at different sites in the study area.Rhinolophus rouxi showed no specialization for any particular insect prey. The diet composition in this species shows a good correspondence to the composition in dry weight of insects collected by light traps. Dipterans were under‐represented in the faeces compared to the numbers trapped. This suggests that R. rouxi forages unselectively on prey larger than the generally very small dipterans. After the first monsoon showers, the remains of beetles, especially scarabaeids, and termites were more common in the faeces of R. rouxi. Bats caught at hourly intervals during one night showed an increase in the proportion of moths consumed.In contrast, H. lankadiva was found to feed mainly on beetles, particularly scarabaeids, together with large, slow‐flying insects such as bugs or nuptial ants. The proportion of beetles (79%‐100%) in the faeces of this species was about three times higher than their representation in the insect collections. This suggests that H. lankudiuu forages selectively.

The tonotopic organization of the inferior colliculus (IC) in two echolocating bats,Hipposideros speoris andMegaderma lyra, was studied by multiunit recordings.

The response of the echolocating bat,Megaderma lyra, was tested to different kinds of prey in an outdoor cage. The bats caught larger flying insects (moths, beetles, grasshoppers, and cockroaches) on the wing and also picked up arthropods (solifugid spiders, beetles and cockroaches) and small vertebrates (mice, fishes, frogs and geckoes) from the ground. After touching the prey with the muzzle, the bats were able to differentiate between species. Scorpions and toads were not taken byM. lyra.

In October 1984 foraging areas and foraging behaviour of the rufous horseshoe bat, Rhinolophus rouxi, were studied around a nursery colony on the hill slopes of Sri Lanka. The bats only foraged in dense forest and were not found in open woodlands (Fig. 1). This strongly supports the hypothesis that detection of fluttering prey is by pure tone echolocation within or close to echo-cluttering foliage. During a first activity period after sunset for about 30–60 min, the bats mainly caught insects on the wing. This was followed by a period of inactivity for another 60–120 min. Thereafter the bats resumed foraging throughout the night. They mainly alighted on specific twigs and foraged in flycatcher style. Individual bats maintained individual foraging areas of about 20x20 m. They stayed in this area throughout the night and returned to the same area on subsequent nights. Within this area the bats generally alighted on twigs at the same spots. Foraging areas were not defended against intruders. The bats echolocated throughout the night at an average repetition rate of 9.6±1.4 sounds/s. While hanging on twigs they scanned the surrounding area for flying prey by turning their bodies continuously around their legs. On average they performed one brief catching flight every 2 min and immediately returned to one of their favourite vantage points. Echolocation sounds may consist of up to three parts, a brief initial frequency-modulated (FM) component, a long constant frequency (CF) part lasting for about 40–50 ms, and a final FM part again (Fig. 4b, c). Adult males and females emitted pure tone frequencies in separate bands, the males from 73.5–77 kHz and the females from 76.5–79 kHz (Fig. 5). During scanning for prey from vantage points, the bats mostly emitted pure tones without any FM component (Fig. 4a). The last few pure tones emitted before take-off were prolonged to about 60 ms duration. The final FM part was therefore not an obligatory component of the echolocation signals in horseshoe bats. During flight and especially during emergence from the cave, most sounds consisted of a pure tone and loud initial and final FM sweeps. We therefore suggest that the initial FM part might also be relevant for echolocation. From our observations we conclude that the FM components are especially important during obstacle avoidance. In most sounds emitted in the field a fainter first harmonic was present. It was usually up to 30 dB fainter than the second harmonic, but in some instances it was as loud or even distinctly louder than the second one (Fig. 6a). Even within one sound the intensity relationship between the two harmonics may be reversed. We therefore suggest that the first harmonic is an integral part of the signal and relevant for information analysis in echolocation.