'Compromise' in Echolocation Calls between Different Colonies of the Intermediate Leaf-Nosed Bat (Hipposideros larvatus).

PubMed

Chen, Yi; Liu, Qi; Su, Qianqian; Sun, Yunxiao; Peng, Xingwen; He, Xiangyang; Zhang, Libiao

2016-01-01

Each animal population has its own acoustic signature which facilitates identification, communication and reproduction. The sonar signals of bats can convey social information, such as species identity and contextual information. The goal of this study was to determine whether bats adjust their echolocation call structures to mutually recognize and communicate when they encounter the bats from different colonies. We used the intermediate leaf-nosed bats (Hipposideros larvatus) as a case study to investigate the variations of echolocation calls when bats from one colony were introduced singly into the home cage of a new colony or two bats from different colonies were cohabitated together for one month. Our experiments showed that the single bat individual altered its peak frequency of echolocation calls to approach the call of new colony members and two bats from different colonies adjusted their call frequencies toward each other to a similar frequency after being chronically cohabitated. These results indicate that the 'compromise' in echolocation calls might be used to ensure effective mutual communication among bats.

‘Compromise’ in Echolocation Calls between Different Colonies of the Intermediate Leaf-Nosed Bat (Hipposideros larvatus)

PubMed Central

Chen, Yi; Liu, Qi; Su, Qianqian; Sun, Yunxiao; Peng, Xingwen; He, Xiangyang; Zhang, Libiao

2016-01-01

Each animal population has its own acoustic signature which facilitates identification, communication and reproduction. The sonar signals of bats can convey social information, such as species identity and contextual information. The goal of this study was to determine whether bats adjust their echolocation call structures to mutually recognize and communicate when they encounter the bats from different colonies. We used the intermediate leaf-nosed bats (Hipposideros larvatus) as a case study to investigate the variations of echolocation calls when bats from one colony were introduced singly into the home cage of a new colony or two bats from different colonies were cohabitated together for one month. Our experiments showed that the single bat individual altered its peak frequency of echolocation calls to approach the call of new colony members and two bats from different colonies adjusted their call frequencies toward each other to a similar frequency after being chronically cohabitated. These results indicate that the ‘compromise’ in echolocation calls might be used to ensure effective mutual communication among bats. PMID:27029005

The evolution of bat vestibular systems in the face of potential antagonistic selection pressures for flight and echolocation.

PubMed

Davies, Kalina T J; Bates, Paul J J; Maryanto, Ibnu; Cotton, James A; Rossiter, Stephen J

2013-01-01

The vestibular system maintains the body's sense of balance and, therefore, was probably subject to strong selection during evolutionary transitions in locomotion. Among mammals, bats possess unique traits that place unusual demands on their vestibular systems. First, bats are capable of powered flight, which in birds is associated with enlarged semicircular canals. Second, many bats have enlarged cochleae associated with echolocation, and both cochleae and semicircular canals share a space within the petrosal bone. To determine how bat vestibular systems have evolved in the face of these pressures, we used micro-CT scans to compare canal morphology across species with contrasting flight and echolocation capabilities. We found no increase in canal radius in bats associated with the acquisition of powered flight, but canal radius did correlate with body mass in bat species from the suborder Yangochiroptera, and also in non-echolocating Old World fruit bats from the suborder Yinpterochiroptera. No such trend was seen in members of the Yinpterochiroptera that use laryngeal echolocation, although canal radius was associated with wing-tip roundedness in this group. We also found that the vestibular system scaled with cochlea size, although the relationship differed in species that use constant frequency echolocation. Across all bats, the shape of the anterior and lateral canals was associated with large cochlea size and small body size respectively, suggesting differential spatial constraints on each canal depending on its orientation within the skull. Thus in many echolocating bats, it seems that the combination of small body size and enlarged cochlea together act as a principal force on the vestibular system. The two main groups of echolocating bats displayed different canal morphologies, in terms of size and shape in relation to body mass and cochlear size, thus suggesting independent evolutionary pathways and offering tentative support for multiple acquisitions of echolocation.

The Evolution of Bat Vestibular Systems in the Face of Potential Antagonistic Selection Pressures for Flight and Echolocation

PubMed Central

Davies, Kalina T. J.; Bates, Paul J. J.; Maryanto, Ibnu; Cotton, James A.; Rossiter, Stephen J.

2013-01-01

The vestibular system maintains the body’s sense of balance and, therefore, was probably subject to strong selection during evolutionary transitions in locomotion. Among mammals, bats possess unique traits that place unusual demands on their vestibular systems. First, bats are capable of powered flight, which in birds is associated with enlarged semicircular canals. Second, many bats have enlarged cochleae associated with echolocation, and both cochleae and semicircular canals share a space within the petrosal bone. To determine how bat vestibular systems have evolved in the face of these pressures, we used micro-CT scans to compare canal morphology across species with contrasting flight and echolocation capabilities. We found no increase in canal radius in bats associated with the acquisition of powered flight, but canal radius did correlate with body mass in bat species from the suborder Yangochiroptera, and also in non-echolocating Old World fruit bats from the suborder Yinpterochiroptera. No such trend was seen in members of the Yinpterochiroptera that use laryngeal echolocation, although canal radius was associated with wing-tip roundedness in this group. We also found that the vestibular system scaled with cochlea size, although the relationship differed in species that use constant frequency echolocation. Across all bats, the shape of the anterior and lateral canals was associated with large cochlea size and small body size respectively, suggesting differential spatial constraints on each canal depending on its orientation within the skull. Thus in many echolocating bats, it seems that the combination of small body size and enlarged cochlea together act as a principal force on the vestibular system. The two main groups of echolocating bats displayed different canal morphologies, in terms of size and shape in relation to body mass and cochlear size, thus suggesting independent evolutionary pathways and offering tentative support for multiple acquisitions of echolocation. PMID:23637943

Vocalization of echolocation-like pulses for interindividual interaction in horseshoe bats (Rhinolophus ferrumequinum).

PubMed

Kobayasi, Kohta I; Hiryu, Shizuko; Shimozawa, Ryota; Riquimaroux, Hiroshi

2012-11-01

Although much is known about the echolocation of horseshoe bats (Rhinolophus spp.), little is known about the characteristics and function of their communication calls. This study focused on a stereotyped behavior of a bat approaching a companion animal in the colony, and examined their interaction and vocalization during this behavior. The bats emit echolocation-like vocalizations when approaching each other and these vocalizations contain a "buildup" pulse sequence, in which the frequency of the pulse increases gradually to normal echolocation pulse frequencies. The results suggest that the echolocation-like pulses serve an important role in communication within the colony.

Finding flowers in the dark: nectar-feeding bats integrate olfaction and echolocation while foraging for nectar

PubMed Central

Gonzalez-Terrazas, Tania P.; Martel, Carlos; Milet-Pinheiro, Paulo; Ayasse, Manfred; Kalko, Elisabeth K. V.; Tschapka, Marco

2016-01-01

Nectar-feeding bats depend mainly on floral nectar to fulfil their energetic requirements. Chiropterophilous flowers generally present strong floral scents and provide conspicuous acoustic echoes to attract bats. While floral scents are assumed to attract bats over long distances, acoustic properties of flower structures may provide detailed information, thus supporting the localization of a flower at close ranges. So far, to our knowledge, there is no study trying to understand the relative importance as well as the combination of these generally coupled cues for detection (presence) and localization (exact position) of open flowers in nature. For a better comprehension of the significance of olfaction and echolocation in the foraging behaviour of nectar-feeding bats, we conducted two-choice experiments with Leptonycteris yerbabuenae. We tested the bats' behaviour in three experimental scenarios with different cues: (i) olfaction versus echolocation, (ii) echolocation versus echolocation and olfaction, and (iii) olfaction versus echolocation and olfaction. We used the floral scent of the bat-pollinated cactus Pachycereus pringlei as olfactory cue and an acrylic paraboloid as acoustic cue. Additionally, we recorded the echolocation behaviour of the bats and analysed the floral scent of P. pringlei. When decoupled cues were offered, bats displayed no preference in choice for any of the two cues. However, bats reacted first to and chose more often the coupled cues. All bats echolocated continuously and broadcast a long terminal group before a successful visit. The floral scent bouquet of P. pringlei is composed of 20 compounds, some of which (e.g. methyl benzoate) were already reported from chiropterophilous plants. Our investigation demonstrates for the first time to our knowledge, that nectar-feeding bats integrate over different sensory modes for detection and precise localization of open flowers. The combined information from olfactory and acoustic cues allows bats to forage more efficiently. PMID:27853595

An aerial-hawking bat uses stealth echolocation to counter moth hearing.

PubMed

Goerlitz, Holger R; ter Hofstede, Hannah M; Zeale, Matt R K; Jones, Gareth; Holderied, Marc W

2010-09-14

Ears evolved in many nocturnal insects, including some moths, to detect bat echolocation calls and evade capture [1, 2]. Although there is evidence that some bats emit echolocation calls that are inconspicuous to eared moths, it is difficult to determine whether this was an adaptation to moth hearing or originally evolved for a different purpose [2, 3]. Aerial-hawking bats generally emit high-amplitude echolocation calls to maximize detection range [4, 5]. Here we present the first example of an echolocation counterstrategy to overcome prey hearing at the cost of reduced detection distance. We combined comparative bat flight-path tracking and moth neurophysiology with fecal DNA analysis to show that the barbastelle, Barbastella barbastellus, emits calls that are 10 to 100 times lower in amplitude than those of other aerial-hawking bats, remains undetected by moths until close, and captures mainly eared moths. Model calculations demonstrate that only bats emitting such low-amplitude calls hear moth echoes before their calls are conspicuous to moths. This stealth echolocation allows the barbastelle to exploit food resources that are difficult to catch for other aerial-hawking bats emitting calls of greater amplitude. Copyright © 2010 Elsevier Ltd. All rights reserved.

Bats aloft: Variation in echolocation call structure at high altitudes

USDA-ARS?s Scientific Manuscript database

Bats alter their echolocation calls in response to changes in ecological and behavioral conditions, but little is known about how they adjust their call structure in response to changes in altitude. This study examines altitudinal variation in the echolocation calls of Brazilian free-tailed bats, T...

Time-frequency and advanced frequency estimation techniques for the investigation of bat echolocation calls.

PubMed

Kopsinis, Yannis; Aboutanios, Elias; Waters, Dean A; McLaughlin, Steve

2010-02-01

In this paper, techniques for time-frequency analysis and investigation of bat echolocation calls are studied. Particularly, enhanced resolution techniques are developed and/or used in this specific context for the first time. When compared to traditional time-frequency representation methods, the proposed techniques are more capable of showing previously unseen features in the structure of bat echolocation calls. It should be emphasized that although the study is focused on bat echolocation recordings, the results are more general and applicable to many other types of signal.

It's not black or white—on the range of vision and echolocation in echolocating bats

PubMed Central

Boonman, Arjan; Bar-On, Yinon; Cvikel, Noam; Yovel, Yossi

2013-01-01

Around 1000 species of bats in the world use echolocation to navigate, orient, and detect insect prey. Many of these bats emerge from their roost at dusk and start foraging when there is still light available. It is however unclear in what way and to which extent navigation, or even prey detection in these bats is aided by vision. Here we compare the echolocation and visual detection ranges of two such species of bats which rely on different foraging strategies (Rhinopoma microphyllum and Pipistrellus kuhlii). We find that echolocation is better than vision for detecting small insects even in intermediate light levels (1–10 lux), while vision is advantageous for monitoring far-away landscape elements in both species. We thus hypothesize that, bats constantly integrate information acquired by the two sensory modalities. We suggest that during evolution, echolocation was refined to detect increasingly small targets in conjunction with using vision. To do so, the ability to hear ultrasonic sound is a prerequisite which was readily available in small mammals, but absent in many other animal groups. The ability to exploit ultrasound to detect very small targets, such as insects, has opened up a large nocturnal niche to bats and may have spurred diversification in both echolocation and foraging tactics. PMID:24065924

When echolocating bats do not echolocate

PubMed Central

Chiu, Chen

2008-01-01

Echolocating bats are known to continuously generate high frequency sonar pulses and listen to the reflecting echoes to localize objects and orient in the environment. However, silent behavior has been reported in a recent paper, which demonstrated that the big brown bat (Eptesicus fuscus) can fly a relative long distant (0.6 to 8 m) without echolocating when flying with another conspecific in a large flight room.1 Methodology and conclusion developed in this study have the potential for further experimental design to answer the question of how millions of bats navigate and orient in cohesive groups. In addition, the discovery of silent behavior suggests the possible use of cooperative sonar in echolocating animals. PMID:19704880

Assessing bat detectability and occupancy with multiple automated echolocation detectors

Treesearch

Marcos P. Gorresen; Adam C. Miles; Christopher M. Todd; Frank J. Bonaccorso; Theodore J. Weller

2008-01-01

Occupancy analysis and its ability to account for differential detection probabilities is important for studies in which detecting echolocation calls is used as a measure of bat occurrence and activity. We examined the feasibility of remotely acquiring bat encounter histories to estimate detection probability and occupancy. We used echolocation detectors coupled o...

Patterns and causes of geographic variation in bat echolocation pulses.

PubMed

Jiang, Tinglei; Wu, Hui; Feng, Jiang

2015-05-01

Evolutionary biologists have a long-standing interest in how acoustic signals in animals vary geographically, because divergent ecology and sensory perception play an important role in speciation. Geographic comparisons are valuable in determining the factors that influence divergence of acoustic signals. Bats are social mammals and they depend mainly on echolocation pulses to locate prey, to navigate and to communicate. Mounting evidence shows that geographic variation of bat echolocation pulses is common, with a mean 5-10 kHz differences in peak frequency, and a high level of individual variation may be nested in this geographical variation. However, understanding the geographic variation of echolocation pulses in bats is very difficult, because of differences in sample and statistical analysis techniques as well as the variety of factors shaping the vocal geographic evolution. Geographic differences in echolocation pulses of bats generally lack latitudinal, longitudinal and elevational patterns, and little is known about vocal dialects. Evidence is accumulating to support the fact that geographic variation in echolocation pulses of bats may be caused by genetic drift, cultural drift, ecological selection, sexual selection and social selection. Future studies could relate geographic differences in echolocation pulses to social adaptation, vocal learning strategies and patterns of dispersal. In addition, new statistical techniques and acoustic playback experiments may help to illustrate the causes and consequences of the geographic evolution of echolocation pulse in bats. © 2015 International Society of Zoological Sciences, Institute of Zoology/Chinese Academy of Sciences and Wiley Publishing Asia Pty Ltd.

Independent Losses of Visual Perception Genes Gja10 and Rbp3 in Echolocating Bats (Order: Chiroptera)

PubMed Central

Shen, Bin; Fang, Tao; Dai, Mengyao; Jones, Gareth; Zhang, Shuyi

2013-01-01

A trade-off between the sensory modalities of vision and hearing is likely to have occurred in echolocating bats as the sophisticated mechanism of laryngeal echolocation requires considerable neural processing and has reduced the reliance of echolocating bats on vision for perceiving the environment. If such a trade-off exists, it is reasonable to hypothesize that some genes involved in visual function may have undergone relaxed selection or even functional loss in echolocating bats. The Gap junction protein, alpha 10 (Gja10, encoded by Gja10 gene) is expressed abundantly in mammal retinal horizontal cells and plays an important role in horizontal cell coupling. The interphotoreceptor retinoid-binding protein (Irbp, encoded by the Rbp3 gene) is mainly expressed in interphotoreceptor matrix and is known to be critical for normal functioning of the visual cycle. We sequenced Gja10 and Rbp3 genes in a taxonomically wide range of bats with divergent auditory characteristics (35 and 18 species for Gja10 and Rbp3, respectively). Both genes have became pseudogenes in species from the families Hipposideridae and Rhinolophidae that emit constant frequency echolocation calls with Doppler shift compensation at high-duty-cycles (the most sophisticated form of biosonar known), and in some bat species that emit echolocation calls at low-duty-cycles. Our study thus provides further evidence for the hypothesis that a trade-off occurs at the genetic level between vision and echolocation in bats. PMID:23874796

Independent losses of visual perception genes Gja10 and Rbp3 in echolocating bats (Order: Chiroptera).

PubMed

Shen, Bin; Fang, Tao; Dai, Mengyao; Jones, Gareth; Zhang, Shuyi

2013-01-01

A trade-off between the sensory modalities of vision and hearing is likely to have occurred in echolocating bats as the sophisticated mechanism of laryngeal echolocation requires considerable neural processing and has reduced the reliance of echolocating bats on vision for perceiving the environment. If such a trade-off exists, it is reasonable to hypothesize that some genes involved in visual function may have undergone relaxed selection or even functional loss in echolocating bats. The Gap junction protein, alpha 10 (Gja10, encoded by Gja10 gene) is expressed abundantly in mammal retinal horizontal cells and plays an important role in horizontal cell coupling. The interphotoreceptor retinoid-binding protein (Irbp, encoded by the Rbp3 gene) is mainly expressed in interphotoreceptor matrix and is known to be critical for normal functioning of the visual cycle. We sequenced Gja10 and Rbp3 genes in a taxonomically wide range of bats with divergent auditory characteristics (35 and 18 species for Gja10 and Rbp3, respectively). Both genes have became pseudogenes in species from the families Hipposideridae and Rhinolophidae that emit constant frequency echolocation calls with Doppler shift compensation at high-duty-cycles (the most sophisticated form of biosonar known), and in some bat species that emit echolocation calls at low-duty-cycles. Our study thus provides further evidence for the hypothesis that a trade-off occurs at the genetic level between vision and echolocation in bats.

Evolutionary origins of ultrasonic hearing and laryngeal echolocation in bats inferred from morphological analyses of the inner ear

PubMed Central

2013-01-01

Introduction Many mammals have evolved highly adapted hearing associated with ecological specialisation. Of these, bats possess the widest frequency range of vocalisations and associated hearing sensitivities, with frequencies of above 200 kHz in some lineages that use laryngeal echolocation. High frequency hearing in bats appears to have evolved via structural modifications of the inner ear, however, studying these minute features presents considerable challenges and hitherto few such attempts have been made. To understand these adaptations more fully, as well as gain insights into the evolutionary origins of ultrasonic hearing and echolocation in bats, we undertook micro-computed tomography (μCT) scans of the cochleae of representative bat species from 16 families, encompassing their broad range of ecological diversity. To characterise cochlear gross morphology, we measured the relative basilar membrane length and number of turns, and compared these values between echolocating and non-echolocating bats, as well as other mammals. Results We found that hearing and echolocation call frequencies in bats correlated with both measures of cochlear morphology. In particular, relative basilar membrane length was typically longer in echolocating species, and also correlated positively with the number of cochlear turns. Ancestral reconstructions of these parameters suggested that the common ancestor of all extant bats was probably capable of ultrasonic hearing; however, we also found evidence of a significant decrease in the rate of morphological evolution of the basilar membrane in multiple ancestral branches within the Yangochiroptera suborder. Within the echolocating Yinpterochiroptera, there was some evidence of an increase in the rate of basilar membrane evolution in some tips of the tree, possibly associated with reported shifts in call frequency associated with recent speciation events. Conclusions The two main groups of echolocating bat were found to display highly variable inner ear morphologies. Ancestral reconstructions and rate shift analyses of ear morphology point to a complex evolutionary history, with the former supporting ultrasonic hearing in the common bat ancestor but the latter suggesting that morphological changes associated with echolocation might have occurred later. These findings are consistent with theories that sophisticated laryngeal echolocation, as seen in modern lineages, evolved following the divergence of the two main suborders. PMID:23360746

A biologically inspired model of bat echolocation in a cluttered environment with inputs designed from field Recordings

NASA Astrophysics Data System (ADS)

Loncich, Kristen Teczar

Bat echolocation strategies and neural processing of acoustic information, with a focus on cluttered environments, is investigated in this study. How a bat processes the dense field of echoes received while navigating and foraging in the dark is not well understood. While several models have been developed to describe the mechanisms behind bat echolocation, most are based in mathematics rather than biology, and focus on either peripheral or neural processing---not exploring how these two levels of processing are vitally connected. Current echolocation models also do not use habitat specific acoustic input, or account for field observations of echolocation strategies. Here, a new approach to echolocation modeling is described capturing the full picture of echolocation from signal generation to a neural picture of the acoustic scene. A biologically inspired echolocation model is developed using field research measurements of the interpulse interval timing used by a frequency modulating (FM) bat in the wild, with a whole method approach to modeling echolocation including habitat specific acoustic inputs, a biologically accurate peripheral model of sound processing by the outer, middle, and inner ear, and finally a neural model incorporating established auditory pathways and neuron types with echolocation adaptations. Field recordings analyzed underscore bat sonar design differences observed in the laboratory and wild, and suggest a correlation between interpulse interval groupings and increased clutter. The scenario model provides habitat and behavior specific echoes and is a useful tool for both modeling and behavioral studies, and the peripheral and neural model show that spike-time information and echolocation specific neuron types can produce target localization in the midbrain.

High duty cycle to low duty cycle: echolocation behaviour of the hipposiderid bat Coelops frithii.

PubMed

Ho, Ying-Yi; Fang, Yin-Ping; Chou, Cheng-Han; Cheng, Hsi-Chi; Chang, Hsueh-Wen

2013-01-01

Laryngeally echolocating bats avoid self-deafening (forward masking) by separating pulse and echo either in time using low duty cycle (LDC) echolocation, or in frequency using high duty cycle (HDC) echolocation. HDC echolocators are specialized to detect fluttering targets in cluttered environments. HDC echolocation is found only in the families Rhinolophidae and Hipposideridae in the Old World and in the New World mormoopid, Pteronotus parnellii. Here we report that the hipposiderid Coelops frithii, ostensibly an HDC bat, consistently uses an LDC echolocation strategy whether roosting, flying, or approaching a fluttering target rotating at 50 to 80 Hz. We recorded the echolocation calls of free-flying C. frithii in the field in various situations, including presenting bats with a mechanical fluttering target. The echolocation calls of C. frithii consisted of an initial narrowband component (0.5±0.3 ms, 90.6±2.0 kHz) followed immediately by a frequency modulated (FM) sweep (194 to 113 kHz). This species emitted echolocation calls at duty cycles averaging 7.7±2.8% (n = 87 sequences). Coelops frithii approached fluttering targets more frequently than did LDC bats (C.frithii, approach frequency  = 40.4%, n = 80; Myotis spp., approach frequency  = 0%, n = 13), and at the same frequency as sympatrically feeding HDC species (Hipposideros armiger, approach rate  = 53.3%, n = 15; Rhinolophus monoceros, approach rate  = 56.7%, n = 97). We propose that the LDC echolocation strategy used by C. frithii is derived from HDC ancestors, that this species adjusts the harmonic contents of its echolocation calls, and that it may use both the narrowband component and the FM sweep of echolocations calls to detect fluttering targets.

High Duty Cycle to Low Duty Cycle: Echolocation Behaviour of the Hipposiderid Bat Coelops frithii

PubMed Central

Ho, Ying-Yi; Fang, Yin-Ping; Chou, Cheng-Han; Cheng, Hsi-Chi; Chang, Hsueh-Wen

2013-01-01

Laryngeally echolocating bats avoid self-deafening (forward masking) by separating pulse and echo either in time using low duty cycle (LDC) echolocation, or in frequency using high duty cycle (HDC) echolocation. HDC echolocators are specialized to detect fluttering targets in cluttered environments. HDC echolocation is found only in the families Rhinolophidae and Hipposideridae in the Old World and in the New World mormoopid, Pteronotus parnellii. Here we report that the hipposiderid Coelops frithii, ostensibly an HDC bat, consistently uses an LDC echolocation strategy whether roosting, flying, or approaching a fluttering target rotating at 50 to 80 Hz. We recorded the echolocation calls of free-flying C. frithii in the field in various situations, including presenting bats with a mechanical fluttering target. The echolocation calls of C. frithii consisted of an initial narrowband component (0.5±0.3 ms, 90.6±2.0 kHz) followed immediately by a frequency modulated (FM) sweep (194 to 113 kHz). This species emitted echolocation calls at duty cycles averaging 7.7±2.8% (n = 87 sequences). Coelops frithii approached fluttering targets more frequently than did LDC bats (C.frithii, approach frequency  = 40.4%, n = 80; Myotis spp., approach frequency  = 0%, n = 13), and at the same frequency as sympatrically feeding HDC species (Hipposideros armiger, approach rate  = 53.3%, n = 15; Rhinolophus monoceros, approach rate  = 56.7%, n = 97). We propose that the LDC echolocation strategy used by C. frithii is derived from HDC ancestors, that this species adjusts the harmonic contents of its echolocation calls, and that it may use both the narrowband component and the FM sweep of echolocations calls to detect fluttering targets. PMID:23717396

A novel biomimetic sonarhead using beamforming technology to mimic bat echolocation.

PubMed

Steckel, Jan; Peremans, Herbert

2012-07-01

A novel biomimetic sonarhead has been developed to allow researchers of bat echolocation behavior and biomimetic sonar to perform experiments with a system similar to the bat¿s sensory system. The bat's echolocation-related transfer function (ERTF) is implemented using an array of receivers to implement the head-related transfer function (HRTF), and an array of emitters mounted on a cylindrical manifold to implement the emission pattern of the bat. The complete system is controlled by a field-programmable gate array (FPGA) based embedded system connected through a USB interface.

Modeling perspectives on echolocation strategies inspired by bats flying in groups.

PubMed

Lin, Yuan; Abaid, Nicole

2015-12-21

Bats navigating with echolocation - which is a type of active sensing achieved by interpreting echoes resulting from self-generated ultrasonic pulses - exhibit unique behaviors during group flight. While bats may benefit from eavesdropping on their peers׳ echolocation, they also potentially suffer from confusion between their own and peers׳ pulses, caused by an effect called frequency jamming. This hardship of group flight is supported by experimental observations of bats simplifying their sound-scape by shifting their pulse frequencies or suppressing echolocation altogether. Here, we investigate eavesdropping and varying pulse emission rate from a modeling perspective to understand these behaviors׳ potential benefits and detriments. We define an agent-based model of echolocating bats avoiding collisions in a three-dimensional tunnel. Through simulation, we show that bats with reasonably accurate eavesdropping can reduce collisions compared to those neglecting information from peers. In large populations, bats minimize frequency jamming by decreasing pulse emission rate, while collision risk increases; conversely, increasing pulse emission rate minimizes collisions by allowing more sensing information generated per bat. These strategies offer benefits for both biological and engineered systems, since frequency jamming is a concern in systems using active sensing. Copyright © 2015 Elsevier Ltd. All rights reserved.

Driving factors for the evolution of species-specific echolocation call design in new world free-tailed bats (molossidae).

PubMed

Jung, Kirsten; Molinari, Jesús; Kalko, Elisabeth K V

2014-01-01

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.

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

PubMed Central

Jung, Kirsten; Molinari, Jesús

2014-01-01

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. PMID:24454833

Neurophysiological analysis of echolocation in bats

NASA Technical Reports Server (NTRS)

Suga, N.

1972-01-01

An analysis of echolocation and signal processing in brown bats is presented. Data cover echo detection, echo ranging, echolocalization, and echo analysis. Efforts were also made to identify the part of the brain that carries out the most essential processing function for echolocation. Results indicate the inferior colliculus and the auditory nuclei function together to process this information.

Interaction of vestibular, echolocation, and visual modalities guiding flight by the big brown bat, Eptesicus fuscus.

PubMed

Horowitz, Seth S; Cheney, Cheryl A; Simmons, James A

2004-01-01

The big brown bat (Eptesicus fuscus) is an aerial-feeding insectivorous species that relies on echolocation to avoid obstacles and to detect flying insects. Spatial perception in the dark using echolocation challenges the vestibular system to function without substantial visual input for orientation. IR thermal video recordings show the complexity of bat flights in the field and suggest a highly dynamic role for the vestibular system in orientation and flight control. To examine this role, we carried out laboratory studies of flight behavior under illuminated and dark conditions in both static and rotating obstacle tests while administering heavy water (D2O) to impair vestibular inputs. Eptesicus carried out complex maneuvers through both fixed arrays of wires and a rotating obstacle array using both vision and echolocation, or when guided by echolocation alone. When treated with D2O in combination with lack of visual cues, bats showed considerable decrements in performance. These data indicate that big brown bats use both vision and echolocation to provide spatial registration for head position information generated by the vestibular system.

Postnatal ontogeny of the cochlea and flight ability in Jamaican fruit bats (Phyllostomidae) with implications for the evolution of echolocation.

PubMed

Carter, Richard T; Adams, Rick A

2015-04-01

Recent evidence has shown that the developmental emergence of echolocation calls in young bats follow an independent developmental pathway from other vocalizations and that adult-like echolocation call structure significantly precedes flight ability. These data in combination with new insights into the echolocation ability of some shrews suggest that the evolution of echolocation in bats may involve inheritance of a primitive sonar system that was modified to its current state, rather than the ad hoc evolution of echolocation in the earliest bats. Because the cochlea is crucial in the sensation of echoes returning from sonar pulses, we tracked changes in cochlear morphology during development that included the basilar membrane (BM) and secondary spiral lamina (SSL) along the length of the cochlea in relation to stages of flight ability in young bats. Our data show that the morphological prerequisite for sonar sensitivity of the cochlea significantly precedes the onset of flight in young bats and, in fact, development of this prerequisite is complete before parturition. In addition, there were no discernible changes in cochlear morphology with stages of flight development, demonstrating temporal asymmetry between the development of morphology associated with echo-pulse return sensitivity and volancy. These data further corroborate and support the hypothesis that adaptations for sonar and echolocation evolved before flight in mammals. © 2015 Anatomical Society.

Tight coordination of aerial flight maneuvers and sonar call production in insectivorous bats

PubMed Central

Falk, Benjamin; Kasnadi, Joseph; Moss, Cynthia F.

2015-01-01

ABSTRACT Echolocating bats face the challenge of coordinating flight kinematics with the production of echolocation signals used to guide navigation. Previous studies of bat flight have focused on kinematics of fruit and nectar-feeding bats, often in wind tunnels with limited maneuvering, and without analysis of echolocation behavior. In this study, we engaged insectivorous big brown bats in a task requiring simultaneous turning and climbing flight, and used synchronized high-speed motion-tracking cameras and audio recordings to quantify the animals' coordination of wing kinematics and echolocation. Bats varied flight speed, turn rate, climb rate and wingbeat rate as they navigated around obstacles, and they adapted their sonar signals in patterning, duration and frequency in relation to the timing of flight maneuvers. We found that bats timed the emission of sonar calls with the upstroke phase of the wingbeat cycle in straight flight, and that this relationship changed when bats turned to navigate obstacles. We also characterized the unsteadiness of climbing and turning flight, as well as the relationship between speed and kinematic parameters. Adaptations in the bats' echolocation call frequency suggest changes in beam width and sonar field of view in relation to obstacles and flight behavior. By characterizing flight and sonar behaviors in an insectivorous bat species, we find evidence of exquisitely tight coordination of sensory and motor systems for obstacle navigation and insect capture. PMID:26582935

Echolocation call intensity and directionality in flying short-tailed fruit bats, Carollia perspicillata (Phyllostomidae).

PubMed

Brinkløv, Signe; Jakobsen, Lasse; Ratcliffe, John M; Kalko, Elisabeth K V; Surlykke, Annemarie

2011-01-01

The directionality of bat echolocation calls defines the width of bats' sonar "view," while call intensity directly influences detection range since adequate sound energy must impinge upon objects to return audible echoes. Both are thus crucial parameters for understanding biosonar signal design. Phyllostomid bats have been classified as low intensity or "whispering bats," but recent data indicate that this designation may be inaccurate. Echolocation beam directionality in phyllostomids has only been measured through electrode brain-stimulation of restrained bats, presumably excluding active beam control via the noseleaf. Here, a 12-microphone array was used to measure echolocation call intensity and beam directionality in the frugivorous phyllostomid, Carollia perspicillata, echolocating in flight. The results showed a considerably narrower beam shape (half-amplitude beam angles of approximately 16° horizontally and 14° vertically) and louder echolocation calls [source levels averaging 99 dB sound pressure level (SPL) root mean square] for C. perspicillata than was found for this species when stationary. This suggests that naturally behaving phyllostomids shape their sound beam to achieve a longer and narrower sonar range than previously thought. C. perspicillata orient and forage in the forest interior and the narrow beam might be adaptive in clutter, by reducing the number and intensity of off-axis echoes.

Adaptations for Substrate Gleaning in Bats: The Pallid Bat as a Case Study.

PubMed

Razak, Khaleel A

2018-06-06

Substrate gleaning is a foraging strategy in which bats use a mixture of echolocation, prey-generated sounds, and vision to localize and hunt surface-dwelling prey. Many substrate-gleaning species depend primarily on prey-generated noise to hunt. Use of echolocation is limited to general orientation and obstacle avoidance. This foraging strategy involves a different set of selective pressures on morphology, behavior, and auditory system organization of bats compared to the use of echolocation for both hunting and navigation. Gleaning likely evolved to hunt in cluttered environments and/or as a counterstrategy to reduce detection by eared prey. Gleaning bats simultaneously receive streams of echoes from obstacles and prey-generated noise, and have to segregate these acoustic streams to attend to one or both. Not only do these bats have to be exquisitely sensitive to the soft, low frequency sounds produced by walking/rustling prey, they also have to precisely localize these sounds. Gleaners typically use low intensity echolocation calls. Such stealth echolocation requires a nervous system that is attuned to low intensity sound processing. In addition, landing on the ground to hunt may bring gleaners in close proximity to venomous prey. In fact, at least 2 gleaning bat species are known to hunt highly venomous scorpions. While a number of studies have addressed adaptations for echolocation in bats that hunt in the air, very little is known about the morphological, behavioral, and neural specializations for gleaning in bats. This review highlights the novel insights gleaning bats provide into bat evolution, particularly auditory pathway organization and ion channel structure/function relationships. Gleaning bats are found in multiple families, suggesting convergent evolution of specializations for gleaning as a foraging strategy. However, most of this review is based on recent work on a single species - the pallid bat (Antrozous palli dus) - symptomatic of the fact that more comparative work is needed to identify the mechanisms that facilitate gleaning behavior. © 2018 S. Karger AG, Basel.

Early milestones in the understanding of echolocation in bats.

PubMed

Grinnell, Alan D

2018-04-23

Almost 80 years ago, Griffin and Galambos discovered the phenomenon of echolocation in bats. Since then, the field has grown exponentially as new generations of investigators have joined the chase and technological advances have revolutionized working with ultrasound in the laboratory and in the field. Today our understanding of the diversity of behavioral and neural adaptations for echolocation constitutes one of the paramount triumphs of neuroethology. At the invitation of the editor in chief, I here review some of the important milestones in the discovery and early understanding of echolocation in bats through about the mid-1980s.

Spike Neuromorphic VLSI-Based Bat Echolocation for Micro-Aerial Vehicle Guidance

DTIC Science & Technology

2007-03-31

IFinal 03/01/04 - 02/28/07 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Neuromorphic VLSI-based Bat Echolocation for Micro-aerial 5b.GRANTNUMBER Vehicle...uncovered interesting new issues in our choice for representing the intensity of signals. We have just finished testing the first chip version of an echo...timing-based algorithm (’openspace’) for sonar-guided navigation amidst multiple obstacles. 15. SUBJECT TERMS Neuromorphic VLSI, bat echolocation

Tight coordination of aerial flight maneuvers and sonar call production in insectivorous bats.

PubMed

Falk, Benjamin; Kasnadi, Joseph; Moss, Cynthia F

2015-11-01

Echolocating bats face the challenge of coordinating flight kinematics with the production of echolocation signals used to guide navigation. Previous studies of bat flight have focused on kinematics of fruit and nectar-feeding bats, often in wind tunnels with limited maneuvering, and without analysis of echolocation behavior. In this study, we engaged insectivorous big brown bats in a task requiring simultaneous turning and climbing flight, and used synchronized high-speed motion-tracking cameras and audio recordings to quantify the animals' coordination of wing kinematics and echolocation. Bats varied flight speed, turn rate, climb rate and wingbeat rate as they navigated around obstacles, and they adapted their sonar signals in patterning, duration and frequency in relation to the timing of flight maneuvers. We found that bats timed the emission of sonar calls with the upstroke phase of the wingbeat cycle in straight flight, and that this relationship changed when bats turned to navigate obstacles. We also characterized the unsteadiness of climbing and turning flight, as well as the relationship between speed and kinematic parameters. Adaptations in the bats' echolocation call frequency suggest changes in beam width and sonar field of view in relation to obstacles and flight behavior. By characterizing flight and sonar behaviors in an insectivorous bat species, we find evidence of exquisitely tight coordination of sensory and motor systems for obstacle navigation and insect capture. © 2015. Published by The Company of Biologists Ltd.

Comparisons of MRI images, and auditory-related and vocal-related protein expressions in the brain of echolocation bats and rodents.

PubMed

Hsiao, Chun-Jen; Hsu, Chih-Hsiang; Lin, Ching-Lung; Wu, Chung-Hsin; Jen, Philip Hung-Sun

2016-08-17

Although echolocating bats and other mammals share the basic design of laryngeal apparatus for sound production and auditory system for sound reception, they have a specialized laryngeal mechanism for ultrasonic sound emissions as well as a highly developed auditory system for processing species-specific sounds. Because the sounds used by bats for echolocation and rodents for communication are quite different, there must be differences in the central nervous system devoted to producing and processing species-specific sounds between them. The present study examines the difference in the relative size of several brain structures and expression of auditory-related and vocal-related proteins in the central nervous system of echolocation bats and rodents. Here, we report that bats using constant frequency-frequency-modulated sounds (CF-FM bats) and FM bats for echolocation have a larger volume of midbrain nuclei (inferior and superior colliculi) and cerebellum relative to the size of the brain than rodents (mice and rats). However, the former have a smaller volume of the cerebrum and olfactory bulb, but greater expression of otoferlin and forkhead box protein P2 than the latter. Although the size of both midbrain colliculi is comparable in both CF-FM and FM bats, CF-FM bats have a larger cerebrum and greater expression of otoferlin and forkhead box protein P2 than FM bats. These differences in brain structure and protein expression are discussed in relation to their biologically relevant sounds and foraging behavior.

Bat guilds, a concept to classify the highly diverse foraging and echolocation behaviors of microchiropteran bats

PubMed Central

Denzinger, Annette; Schnitzler, Hans-Ulrich

2013-01-01

Throughout evolution the foraging and echolocation behaviors as well as the motor systems of bats have been adapted to the tasks they have to perform while searching and acquiring food. When bats exploit the same class of environmental resources in a similar way, they perform comparable tasks and thus share similar adaptations independent of their phylogeny. Species with similar adaptations are assigned to guilds or functional groups. Habitat type and foraging mode mainly determine the foraging tasks and thus the adaptations of bats. Therefore, we use habitat type and foraging mode to define seven guilds. The habitat types open, edge and narrow space are defined according to the bats' echolocation behavior in relation to the distance between bat and background or food item and background. Bats foraging in the aerial, trawling, flutter detecting, or active gleaning mode use only echolocation to acquire their food. When foraging in the passive gleaning mode bats do not use echolocation but rely on sensory cues from the food item to find it. Bat communities often comprise large numbers of species with a high diversity in foraging areas, foraging modes, and diets. The assignment of species living under similar constraints into guilds identifies patterns of community structure and helps to understand the factors that underlie the organization of highly diverse bat communities. Bat species from different guilds do not compete for food as they differ in their foraging behavior and in the environmental resources they use. However, sympatric living species belonging to the same guild often exploit the same class of resources. To avoid competition they should differ in their niche dimensions. The fine grain structure of bat communities below the rather coarse classification into guilds is determined by mechanisms that result in niche partitioning. PMID:23840190

The adaptive function of tiger moth clicks against echolocating bats: an experimental and synthetic approach.

PubMed

Ratcliffe, John M; Fullard, James H

2005-12-01

We studied the efficiency and effects of the multiple sensory cues of tiger moths on echolocating bats. We used the northern long-eared bat, Myotis septentrionalis, a purported moth specialist that takes surface-bound prey (gleaning) and airborne prey (aerial hawking), and the dogbane tiger moth, Cycnia tenera, an eared species unpalatable to bats that possesses conspicuous colouration and sound-producing organs (tymbals). This is the first study to investigate the interaction of tiger moths and wild-caught bats under conditions mimicking those found in nature and to demand the use of both aerial hawking and gleaning strategies by bats. Further, it is the first to report spectrograms of the sounds produced by tiger moths while under aerial attack by echolocating bats. During both aerial hawking and gleaning trials, all muted C. tenera and perched intact C. tenera were attacked by M. septentrionalis, indicating that M. septentrionalis did not discriminate C. tenera from palatable moths based on potential echoic and/or non-auditory cues. Intact C. tenera were attacked significantly less often than muted C. tenera during aerial hawking attacks: tymbal clicks were therefore an effective deterrent in an aerial hawking context. During gleaning attacks, intact and muted C. tenera were always attacked and suffered similar mortality rates, suggesting that while handling prey this bat uses primarily chemical signals. Our results also show that C. tenera temporally matches the onset of click production to the ;approach phase' echolocation calls produced by aerial hawking attacking bats and that clicks themselves influence the echolocation behaviour of attacking bats. In the context of past research, these findings support the hypotheses that the clicks of arctiid moths are both an active defence (through echolocation disruption) and a reliable indicator of chemical defence against aerial-hawking bats. We suggest these signals are specialized for an aerial context.

Parallel sites implicate functional convergence of the hearing gene prestin among echolocating mammals.

PubMed

Liu, Zhen; Qi, Fei-Yan; Zhou, Xin; Ren, Hai-Qing; Shi, Peng

2014-09-01

Echolocation is a sensory system whereby certain mammals navigate and forage using sound waves, usually in environments where visibility is limited. Curiously, echolocation has evolved independently in bats and whales, which occupy entirely different environments. Based on this phenotypic convergence, recent studies identified several echolocation-related genes with parallel sites at the protein sequence level among different echolocating mammals, and among these, prestin seems the most promising. Although previous studies analyzed the evolutionary mechanism of prestin, the functional roles of the parallel sites in the evolution of mammalian echolocation are not clear. By functional assays, we show that a key parameter of prestin function, 1/α, is increased in all echolocating mammals and that the N7T parallel substitution accounted for this functional convergence. Moreover, another parameter, V1/2, was shifted toward the depolarization direction in a toothed whale, the bottlenose dolphin (Tursiops truncatus) and a constant-frequency (CF) bat, the Stoliczka's trident bat (Aselliscus stoliczkanus). The parallel site of I384T between toothed whales and CF bats was responsible for this functional convergence. Furthermore, the two parameters (1/α and V1/2) were correlated with mammalian high-frequency hearing, suggesting that the convergent changes of the prestin function in echolocating mammals may play important roles in mammalian echolocation. To our knowledge, these findings present the functional patterns of echolocation-related genes in echolocating mammals for the first time and rigorously demonstrate adaptive parallel evolution at the protein sequence level, paving the way to insights into the molecular mechanism underlying mammalian echolocation. © The Author 2014. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Testing Convergent Evolution in Auditory Processing Genes between Echolocating Mammals and the Aye-Aye, a Percussive-Foraging Primate.

PubMed

Bankoff, Richard J; Jerjos, Michael; Hohman, Baily; Lauterbur, M Elise; Kistler, Logan; Perry, George H

2017-07-01

Several taxonomically distinct mammalian groups-certain microbats and cetaceans (e.g., dolphins)-share both morphological adaptations related to echolocation behavior and strong signatures of convergent evolution at the amino acid level across seven genes related to auditory processing. Aye-ayes (Daubentonia madagascariensis) are nocturnal lemurs with a specialized auditory processing system. Aye-ayes tap rapidly along the surfaces of trees, listening to reverberations to identify the mines of wood-boring insect larvae; this behavior has been hypothesized to functionally mimic echolocation. Here we investigated whether there are signals of convergence in auditory processing genes between aye-ayes and known mammalian echolocators. We developed a computational pipeline (Basic Exon Assembly Tool) that produces consensus sequences for regions of interest from shotgun genomic sequencing data for nonmodel organisms without requiring de novo genome assembly. We reconstructed complete coding region sequences for the seven convergent echolocating bat-dolphin genes for aye-ayes and another lemur. We compared sequences from these two lemurs in a phylogenetic framework with those of bat and dolphin echolocators and appropriate nonecholocating outgroups. Our analysis reaffirms the existence of amino acid convergence at these loci among echolocating bats and dolphins; some methods also detected signals of convergence between echolocating bats and both mice and elephants. However, we observed no significant signal of amino acid convergence between aye-ayes and echolocating bats and dolphins, suggesting that aye-aye tap-foraging auditory adaptations represent distinct evolutionary innovations. These results are also consistent with a developing consensus that convergent behavioral ecology does not reliably predict convergent molecular evolution. © The Author 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

Acoustic behavior of echolocating bats in complex environments

NASA Astrophysics Data System (ADS)

Moss, Cynthia; Ghose, Kaushik; Jensen, Marianne; Surlykke, Annemarie

2004-05-01

The echolocating bat controls the direction of its sonar beam, just as visually dominant animals control the movement of their eyes to foveate targets of interest. The sonar beam aim of the echolocating bat can therefore serve as an index of the animal's attention to objects in the environment. Until recently, spatial attention has not been studied in the context of echolocation, perhaps due to the difficulty in obtaining an objective measure. Here, we describe measurements of the bat's sonar beam aim, serving as an index of acoustic gaze and attention to objects, in tasks that require localization of obstacles and insect prey. Measurements of the bat's sonar beam aim are taken from microphone array recordings of vocal signals produced by a free-flying bat under experimentally controlled conditions. In some situations, the animal relies on spatial memory over reflected sounds, perhaps because its perceptual system cannot easily organize cascades of echoes from obstacles and prey. This highlights the complexity of the bat's orientation behavior, which can alternate between active sensing and spatial memory systems. The bat's use of spatial memory for orientation also will be addressed in this talk. [Work supported by NSF-IBN-0111973 and the Danish Research Council.

Female Mate Choice Can Drive the Evolution of High Frequency Echolocation in Bats: A Case Study with Rhinolophus mehelyi

PubMed Central

Puechmaille, Sébastien J.; Borissov, Ivailo M.; Zsebok, Sándor; Allegrini, Benjamin; Hizem, Mohammed; Kuenzel, Sven; Schuchmann, Maike; Teeling, Emma C.

2014-01-01

Animals employ an array of signals (i.e. visual, acoustic, olfactory) for communication. Natural selection favours signals, receptors, and signalling behaviour that optimise the received signal relative to background noise. When the signal is used for more than one function, antagonisms amongst the different signalling functions may constrain the optimisation of the signal for any one function. Sexual selection through mate choice can strongly modify the effects of natural selection on signalling systems ultimately causing maladaptive signals to evolve. Echolocating bats represent a fascinating group in which to study the evolution of signalling systems as unlike bird songs or frog calls, echolocation has a dual role in foraging and communication. The function of bat echolocation is to generate echoes that the calling bat uses for orientation and food detection with call characteristics being directly related to the exploitation of particular ecological niches. Therefore, it is commonly assumed that echolocation has been shaped by ecology via natural selection. Here we demonstrate for the first time using a novel combined behavioural, ecological and genetic approach that in a bat species, Rhinolophus mehelyi: (1) echolocation peak frequency is an honest signal of body size; (2) females preferentially select males with high frequency calls during the mating season; (3) high frequency males sire more off-spring, providing evidence that echolocation calls may play a role in female mate choice. Our data refute the sole role of ecology in the evolution of echolocation and highlight the antagonistic interplay between natural and sexual selection in shaping acoustic signals. PMID:25075972

Female mate choice can drive the evolution of high frequency echolocation in bats: a case study with Rhinolophus mehelyi.

PubMed

Puechmaille, Sébastien J; Borissov, Ivailo M; Zsebok, Sándor; Allegrini, Benjamin; Hizem, Mohammed; Kuenzel, Sven; Schuchmann, Maike; Teeling, Emma C; Siemers, Björn M

2014-01-01

Animals employ an array of signals (i.e. visual, acoustic, olfactory) for communication. Natural selection favours signals, receptors, and signalling behaviour that optimise the received signal relative to background noise. When the signal is used for more than one function, antagonisms amongst the different signalling functions may constrain the optimisation of the signal for any one function. Sexual selection through mate choice can strongly modify the effects of natural selection on signalling systems ultimately causing maladaptive signals to evolve. Echolocating bats represent a fascinating group in which to study the evolution of signalling systems as unlike bird songs or frog calls, echolocation has a dual role in foraging and communication. The function of bat echolocation is to generate echoes that the calling bat uses for orientation and food detection with call characteristics being directly related to the exploitation of particular ecological niches. Therefore, it is commonly assumed that echolocation has been shaped by ecology via natural selection. Here we demonstrate for the first time using a novel combined behavioural, ecological and genetic approach that in a bat species, Rhinolophus mehelyi: (1) echolocation peak frequency is an honest signal of body size; (2) females preferentially select males with high frequency calls during the mating season; (3) high frequency males sire more off-spring, providing evidence that echolocation calls may play a role in female mate choice. Our data refute the sole role of ecology in the evolution of echolocation and highlight the antagonistic interplay between natural and sexual selection in shaping acoustic signals.

The influence of bat echolocation call duration and timing on auditory encoding of predator distance in noctuoid moths.

PubMed

Gordon, Shira D; Ter Hofstede, Hannah M

2018-03-22

Animals co-occur with multiple predators, making sensory systems that can encode information about diverse predators advantageous. Moths in the families Noctuidae and Erebidae have ears with two auditory receptor cells (A1 and A2) used to detect the echolocation calls of predatory bats. Bat communities contain species that vary in echolocation call duration, and the dynamic range of A1 is limited by the duration of sound, suggesting that A1 provides less information about bats with shorter echolocation calls. To test this hypothesis, we obtained intensity-response functions for both receptor cells across many moth species for sound pulse durations representing the range of echolocation call durations produced by bat species in northeastern North America. We found that the threshold and dynamic range of both cells varied with sound pulse duration. The number of A1 action potentials per sound pulse increases linearly with increasing amplitude for long-duration pulses, saturating near the A2 threshold. For short sound pulses, however, A1 saturates with only a few action potentials per pulse at amplitudes far lower than the A2 threshold for both single sound pulses and pulse sequences typical of searching or approaching bats. Neural adaptation was only evident in response to approaching bat sequences at high amplitudes, not search-phase sequences. These results show that, for short echolocation calls, a large range of sound levels cannot be coded by moth auditory receptor activity, resulting in no information about the distance of a bat, although differences in activity between ears might provide information about direction. © 2018. Published by The Company of Biologists Ltd.

Active acoustic interference elicits echolocation changes in heterospecific bats.

PubMed

Jones, Te K; Wohlgemuth, Melville J; Conner, William E

2018-06-27

Echolocating bats often forage in the presence of both conspecific and heterospecific individuals who have the potential to produce acoustic interference. Recent studies have shown that at least one bat species, the Brazilian free-tailed bat ( Tadarida brasiliensis ), produces specialized social signals that disrupt the sonar of conspecific competitors. We herein discuss the differences between passive and active jamming signals and test whether heterospecific jamming occurs in species overlapping spatiotemporally as well as whether such interference elicits a jamming avoidance response (JAR). We compare the capture rates of tethered moths and the echolocation parameters of big brown bats ( Eptesicus fuscus ) challenged with the playback of the jamming signal normally produced by Brazilian free-tailed bats and playback of deconstructed versions of this signal. There were no differences in the capture rates of targets with and without the jamming signal although significant changes in both spectral and temporal features of the bats' echolocation were observed. These changes are consistent with improvements of the signal-to-noise ratio in the presence of acoustic interference. Accordingly, we propose to expand the traditional definition of the JAR, stating that echolocation changes in response to interference should decrease similarity between the two signals, to include any change that increases the ability to separate returning echoes from active jamming stimuli originating from conspecific and heterospecific organisms. Flexibility in echolocation is an important characteristic for overcoming various forms of acoustic interference and may serve a purpose in interspecific interactions as well as intraspecific ones. © 2018. Published by The Company of Biologists Ltd.

Allen's big-eared bat (Idionycteris phyllotis) documented in colorado based on recordings of its distinctive echolocation call

USGS Publications Warehouse

Hayes, M.A.; Navo, K.W.; Bonewell, L.; Mosch, C.J.; Adams, Rick A.

2009-01-01

Allen's big-eared bat (Idionycteris phyllotis) inhabits much of the southwestern USA, but has not been documented in Colorado. We recorded echolocation calls consistent with I. phyllotis near La Sal Creek, Montrose County, Colorado. Based on characteristics of echolocation calls and flight behavior, we conclude that the echolocation calls described here were emitted by I. phyllotis and that they represent the first documentation of this species in Colorado.

Behavioral evidence for community-wide species discrimination from echolocation calls in bats.

PubMed

Schuchmann, Maike; Siemers, Björn M

2010-07-01

Recognizing species identity is crucial for many aspects of animal life and is often mediated by acoustic signals. Although most animals are able to distinguish acoustic signals of their own species from other sympatrically occurring species, it is yet unknown whether animals can distinguish among acoustic signals of different closely related sympatric species. In this context, echolocating bats are a particularly interesting model system: their echolocation system evolved primarily for spatial orientation and foraging, but recent studies indicate that echolocation also has an important communicative function. Yet, the role of echolocation calls for species discrimination and thus potentially for interspecific communication has not been investigated. Using a behavioral discrimination assay, we found that two species of wild horseshoe bats could discriminate calls of their own species from those of three sympatric congeneric species. We further show that the bats were able to discriminate between echolocation calls of different congeneric species from the local community. In both cases, discrimination ability was high despite strong overlap of species' call frequency bands. This study provides the first experimental evidence for species discrimination based on echolocation calls. On a more general level, it shows for the first time that animals can distinguish among acoustic signals of different closely related and ecologically similar species from their local community.

Perception of silent and motionless prey on vegetation by echolocation in the gleaning bat Micronycteris microtis.

PubMed

Geipel, Inga; Jung, Kirsten; Kalko, Elisabeth K V

2013-03-07

Gleaning insectivorous bats that forage by using echolocation within dense forest vegetation face the sensorial challenge of acoustic masking effects. Active perception of silent and motionless prey in acoustically cluttered environments by echolocation alone has thus been regarded impossible. The gleaning insectivorous bat Micronycteris microtis however, forages in dense understory vegetation and preys on insects, including dragonflies, which rest silent and motionless on vegetation. From behavioural experiments, we show that M. microtis uses echolocation as the sole sensorial modality for successful prey perception within a complex acoustic environment. All individuals performed a stereotypical three-dimensional hovering flight in front of prey items, while continuously emitting short, multi-harmonic, broadband echolocation calls. We observed a high precision in target localization which suggests that M. microtis perceives a detailed acoustic image of the prey based on shape, surface structure and material. Our experiments provide, to our knowledge, the first evidence that a gleaning bat uses echolocation alone for successful detection, classification and precise localization of silent and motionless prey in acoustic clutter. Overall, we conclude that the three-dimensional hovering flight of M. microtis in combination with a frequent emission of short, high-frequency echolocation calls is the key for active prey perception in acoustically highly cluttered environments.

Perception of silent and motionless prey on vegetation by echolocation in the gleaning bat Micronycteris microtis

PubMed Central

Geipel, Inga; Jung, Kirsten; Kalko, Elisabeth K. V.

2013-01-01

Gleaning insectivorous bats that forage by using echolocation within dense forest vegetation face the sensorial challenge of acoustic masking effects. Active perception of silent and motionless prey in acoustically cluttered environments by echolocation alone has thus been regarded impossible. The gleaning insectivorous bat Micronycteris microtis however, forages in dense understory vegetation and preys on insects, including dragonflies, which rest silent and motionless on vegetation. From behavioural experiments, we show that M. microtis uses echolocation as the sole sensorial modality for successful prey perception within a complex acoustic environment. All individuals performed a stereotypical three-dimensional hovering flight in front of prey items, while continuously emitting short, multi-harmonic, broadband echolocation calls. We observed a high precision in target localization which suggests that M. microtis perceives a detailed acoustic image of the prey based on shape, surface structure and material. Our experiments provide, to our knowledge, the first evidence that a gleaning bat uses echolocation alone for successful detection, classification and precise localization of silent and motionless prey in acoustic clutter. Overall, we conclude that the three-dimensional hovering flight of M. microtis in combination with a frequent emission of short, high-frequency echolocation calls is the key for active prey perception in acoustically highly cluttered environments. PMID:23325775

Innate recognition of water bodies in echolocating bats.

PubMed

Greif, Stefan; Siemers, Björn M

2010-11-02

In the course of their lives, most animals must find different specific habitat and microhabitat types for survival and reproduction. Yet, in vertebrates, little is known about the sensory cues that mediate habitat recognition. In free flying bats the echolocation of insect-sized point targets is well understood, whereas how they recognize and classify spatially extended echo targets is currently unknown. In this study, we show how echolocating bats recognize ponds or other water bodies that are crucial for foraging, drinking and orientation. With wild bats of 15 different species (seven genera from three phylogenetically distant, large bat families), we found that bats perceived any extended, echo-acoustically smooth surface to be water, even in the presence of conflicting information from other sensory modalities. In addition, naive juvenile bats that had never before encountered a water body showed spontaneous drinking responses from smooth plates. This provides the first evidence for innate recognition of a habitat cue in a mammal.

Sensorimotor Model of Obstacle Avoidance in Echolocating Bats

PubMed Central

Vanderelst, Dieter; Holderied, Marc W.; Peremans, Herbert

2015-01-01

Bat echolocation is an ability consisting of many subtasks such as navigation, prey detection and object recognition. Understanding the echolocation capabilities of bats comes down to isolating the minimal set of acoustic cues needed to complete each task. For some tasks, the minimal cues have already been identified. However, while a number of possible cues have been suggested, little is known about the minimal cues supporting obstacle avoidance in echolocating bats. In this paper, we propose that the Interaural Intensity Difference (IID) and travel time of the first millisecond of the echo train are sufficient cues for obstacle avoidance. We describe a simple control algorithm based on the use of these cues in combination with alternating ear positions modeled after the constant frequency bat Rhinolophus rouxii. Using spatial simulations (2D and 3D), we show that simple phonotaxis can steer a bat clear from obstacles without performing a reconstruction of the 3D layout of the scene. As such, this paper presents the first computationally explicit explanation for obstacle avoidance validated in complex simulated environments. Based on additional simulations modelling the FM bat Phyllostomus discolor, we conjecture that the proposed cues can be exploited by constant frequency (CF) bats and frequency modulated (FM) bats alike. We hypothesize that using a low level yet robust cue for obstacle avoidance allows bats to comply with the hard real-time constraints of this basic behaviour. PMID:26502063

Parallel evolution of auditory genes for echolocation in bats and toothed whales.

PubMed

Shen, Yong-Yi; Liang, Lu; Li, Gui-Sheng; Murphy, Robert W; Zhang, Ya-Ping

2012-06-01

The ability of bats and toothed whales to echolocate is a remarkable case of convergent evolution. Previous genetic studies have documented parallel evolution of nucleotide sequences in Prestin and KCNQ4, both of which are associated with voltage motility during the cochlear amplification of signals. Echolocation involves complex mechanisms. The most important factors include cochlear amplification, nerve transmission, and signal re-coding. Herein, we screen three genes that play different roles in this auditory system. Cadherin 23 (Cdh23) and its ligand, protocadherin 15 (Pcdh15), are essential for bundling motility in the sensory hair. Otoferlin (Otof) responds to nerve signal transmission in the auditory inner hair cell. Signals of parallel evolution occur in all three genes in the three groups of echolocators--two groups of bats (Yangochiroptera and Rhinolophoidea) plus the dolphin. Significant signals of positive selection also occur in Cdh23 in the Rhinolophoidea and dolphin, and Pcdh15 in Yangochiroptera. In addition, adult echolocating bats have higher levels of Otof expression in the auditory cortex than do their embryos and non-echolocation bats. Cdh23 and Pcdh15 encode the upper and lower parts of tip-links, and both genes show signals of convergent evolution and positive selection in echolocators, implying that they may co-evolve to optimize cochlear amplification. Convergent evolution and expression patterns of Otof suggest the potential role of nerve and brain in echolocation. Our synthesis of gene sequence and gene expression analyses reveals that positive selection, parallel evolution, and perhaps co-evolution and gene expression affect multiple hearing genes that play different roles in audition, including voltage and bundle motility in cochlear amplification, nerve transmission, and brain function.

Auditory cortex of newborn bats is prewired for echolocation.

PubMed

Kössl, Manfred; Voss, Cornelia; Mora, Emanuel C; Macias, Silvio; Foeller, Elisabeth; Vater, Marianne

2012-04-10

Neuronal computation of object distance from echo delay is an essential task that echolocating bats must master for spatial orientation and the capture of prey. In the dorsal auditory cortex of bats, neurons specifically respond to combinations of short frequency-modulated components of emitted call and delayed echo. These delay-tuned neurons are thought to serve in target range calculation. It is unknown whether neuronal correlates of active space perception are established by experience-dependent plasticity or by innate mechanisms. Here we demonstrate that in the first postnatal week, before onset of echolocation and flight, dorsal auditory cortex already contains functional circuits that calculate distance from the temporal separation of a simulated pulse and echo. This innate cortical implementation of a purely computational processing mechanism for sonar ranging should enhance survival of juvenile bats when they first engage in active echolocation behaviour and flight.

Testing Convergent Evolution in Auditory Processing Genes between Echolocating Mammals and the Aye-Aye, a Percussive-Foraging Primate

PubMed Central

Jerjos, Michael; Hohman, Baily; Lauterbur, M. Elise; Kistler, Logan

2017-01-01

Abstract Several taxonomically distinct mammalian groups—certain microbats and cetaceans (e.g., dolphins)—share both morphological adaptations related to echolocation behavior and strong signatures of convergent evolution at the amino acid level across seven genes related to auditory processing. Aye-ayes (Daubentonia madagascariensis) are nocturnal lemurs with a specialized auditory processing system. Aye-ayes tap rapidly along the surfaces of trees, listening to reverberations to identify the mines of wood-boring insect larvae; this behavior has been hypothesized to functionally mimic echolocation. Here we investigated whether there are signals of convergence in auditory processing genes between aye-ayes and known mammalian echolocators. We developed a computational pipeline (Basic Exon Assembly Tool) that produces consensus sequences for regions of interest from shotgun genomic sequencing data for nonmodel organisms without requiring de novo genome assembly. We reconstructed complete coding region sequences for the seven convergent echolocating bat–dolphin genes for aye-ayes and another lemur. We compared sequences from these two lemurs in a phylogenetic framework with those of bat and dolphin echolocators and appropriate nonecholocating outgroups. Our analysis reaffirms the existence of amino acid convergence at these loci among echolocating bats and dolphins; some methods also detected signals of convergence between echolocating bats and both mice and elephants. However, we observed no significant signal of amino acid convergence between aye-ayes and echolocating bats and dolphins, suggesting that aye-aye tap-foraging auditory adaptations represent distinct evolutionary innovations. These results are also consistent with a developing consensus that convergent behavioral ecology does not reliably predict convergent molecular evolution. PMID:28810710

Fast sensory–motor reactions in echolocating bats to sudden changes during the final buzz and prey intercept

PubMed Central

Geberl, Cornelia; Brinkløv, Signe; Wiegrebe, Lutz; Surlykke, Annemarie

2015-01-01

Echolocation is an active sense enabling bats and toothed whales to orient in darkness through echo returns from their ultrasonic signals. Immediately before prey capture, both bats and whales emit a buzz with such high emission rates (≥180 Hz) and overall duration so short that its functional significance remains an enigma. To investigate sensory–motor control during the buzz of the insectivorous bat Myotis daubentonii, we removed prey, suspended in air or on water, before expected capture. The bats responded by shortening their echolocation buzz gradually; the earlier prey was removed down to approximately 100 ms (30 cm) before expected capture, after which the full buzz sequence was emitted both in air and over water. Bats trawling over water also performed the full capture behavior, but in-air capture motions were aborted, even at very late prey removals (<20 ms = 6 cm before expected contact). Thus, neither the buzz nor capture movements are stereotypical, but dynamically adapted based on sensory feedback. The results indicate that echolocation is controlled mainly by acoustic feedback, whereas capture movements are adjusted according to both acoustic and somatosensory feedback, suggesting separate (but coordinated) central motor control of the two behaviors based on multimodal input. Bat echolocation, especially the terminal buzz, provides a unique window to extremely fast decision processes in response to sensory feedback and modulation through attention in a naturally behaving animal. PMID:25775538

Adaptive echolocation behavior in bats for the analysis of auditory scenes

PubMed Central

Chiu, Chen; Xian, Wei; Moss, Cynthia F.

2009-01-01

Summary Echolocating bats emit sonar pulses and listen to returning echoes to probe their surroundings. Bats adapt their echolocation call design to cope with dynamic changes in the acoustic environment, including habitat change or the presence of nearby conspecifics/heterospecifics. Seven pairs of big brown bats, Eptesicus fuscus, were tested in this study to examine how they adjusted their echolocation calls when flying and competing with a conspecific for food. Results showed that differences in five call parameters, start/end frequencies, duration, bandwidth and sweep rate, significantly increased in the two-bat condition compared with the baseline data. In addition, the magnitude of spectral separation of calls was negatively correlated with the baseline call design differences in individual bats. Bats with small baseline call frequency differences showed larger increases in call frequency separation when paired than those with large baseline call frequency differences, suggesting that bats actively change their sonar call structure if pre-existing differences in call design are small. Call design adjustments were also influenced by physical spacing between two bats. Calls of paired bats exhibited the largest design separations when inter-bat distance was shorter than 0.5 m, and the separation decreased as the spacing increased. All individuals modified at least one baseline call parameter in response to the presence of another conspecific. We propose that dissimilarity between the time–frequency features of sonar calls produced by different bats aids each individual in segregating echoes of its own sonar vocalizations from the acoustic signals of neighboring bats. PMID:19376960

Flexible echolocation behavior of trawling bats during approach of continuous or transient prey cues

PubMed Central

Übernickel, Kirstin; Tschapka, Marco; Kalko, Elisabeth K. V.

2013-01-01

Trawling bats use echolocation not only to detect and classify acoustically continuous cues originated from insects at and above water surfaces, but also to detect small water-dwelling prey items breaking the water surface for a very short time, producing only transient cues to be perceived acoustically. Generally, bats need to adjust their echolocation behavior to the specific task on hand, and because of the diversity of prey cues they use in hunting, trawling bats should be highly flexible in their echolocation behavior. We studied the adaptations in the behavior of Noctilio leporinus when approaching either a continuous cue or a transient cue that disappeared during the approach of the bat. Normally the bats reacted by dipping their feet in the water at the cue location. We found that the bats typically started to adapt their calling behavior at approximately 410 ms before prey contact in continuous cue trials, but were also able to adapt their approach behavior to stimuli onsets as short as 177 ms before contact, within a minimum reaction time of 50.9 ms in response to transient cues. In both tasks the approach phase ended between 32 and 53 ms before prey contact. Call emission always continued after the end of the approach phase until around prey contact. In some failed capture attempts, call emission did not cease at all after prey contact. Probably bats used spatial memory to dip at the original location of the transient cue after its disappearance. The duration of the pointed dips was significantly longer in transient cue trials than in continuous cue trials. Our results suggest that trawling bats possess the ability to modify their generally rather stereotyped echolocation behavior during approaches within very short reaction times depending on the sensory information available. PMID:23675352

Context-dependent effects of noise on echolocation pulse characteristics in free-tailed bats

PubMed Central

Smotherman, Michael S.

2010-01-01

Background noise evokes a similar suite of adaptations in the acoustic structure of communication calls across a diverse range of vertebrates. Echolocating bats may have evolved specialized vocal strategies for echolocating in noise, but also seem to exhibit generic vertebrate responses such as the ubiquitous Lombard response. We wondered how bats balance generic and echolocation-specific vocal responses to noise. To address this question, we first characterized the vocal responses of flying free-tailed bats (Tadarida brasiliensis) to broadband noises varying in amplitude. Secondly, we measured the bats’ responses to band-limited noises that varied in the extent of overlap with their echolocation pulse bandwidth. We hypothesized that the bats’ generic responses to noise would be graded proportionally with noise amplitude, total bandwidth and frequency content, and consequently that more selective responses to band-limited noise such as the jamming avoidance response could be explained by a linear decomposition of the response to broadband noise. Instead, the results showed that both the nature and the magnitude of the vocal responses varied with the acoustic structure of the outgoing pulse as well as non-linearly with noise parameters. We conclude that free-tailed bats utilize separate generic and specialized vocal responses to noise in a context-dependent fashion. PMID:19672604

Adaptive changes in echolocation sounds by Pipistrellus abramus in response to artificial jamming sounds.

PubMed

Takahashi, Eri; Hyomoto, Kiri; Riquimaroux, Hiroshi; Watanabe, Yoshiaki; Ohta, Tetsuo; Hiryu, Shizuko

2014-08-15

The echolocation behavior of Pipistrellus abramus during exposure to artificial jamming sounds during flight was investigated. Echolocation pulses emitted by the bats were recorded using a telemetry microphone mounted on the bats' backs, and their adaptation based on acoustic characteristics of emitted pulses was assessed in terms of jamming-avoidance responses (JARs). In experiment 1, frequency-modulated jamming sounds (3 ms duration) mimicking echolocation pulses of P. abramus were prepared. All bats showed significant increases in the terminal frequency of the frequency-modulated pulse by an average of 2.1-4.5 kHz when the terminal frequency of the jamming sounds was lower than the bats' own pulses. This frequency shift was not observed using jamming frequencies that overlapped with or were higher than the bats' own pulses. These findings suggest that JARs in P. abramus are sensitive to the terminal frequency of jamming pulses and that the bats' response pattern was dependent on the slight difference in stimulus frequency. In experiment 2, when bats were repeatedly exposed to a band-limited noise of 70 ms duration, the bats in flight more frequently emitted pulses during silent periods between jamming sounds, suggesting that the bats could actively change the timing of pulse emissions, even during flight, to avoid temporal overlap with jamming sounds. Our findings demonstrate that bats could adjust their vocalized frequency and emission timing during flight in response to acoustic jamming stimuli. © 2014. Published by The Company of Biologists Ltd.

Gleaning bat echolocation calls do not elicit antipredator behaviour in the Pacific field cricket, Teleogryllus oceanicus (Orthoptera: Gryllidae).

PubMed

ter Hofstede, Hannah M; Killow, Joanne; Fullard, James H

2009-08-01

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.

Listening for bats: the hearing range of the bushcricket Phaneroptera falcata for bat echolocation calls measured in the field.

PubMed Central

Schul, J; Matt, F; von Helversen, O

2000-01-01

The hearing range of the tettigoniid Phaneropterafalcata for the echolocation calls of freely flying mouseeared bats (Myotis myotis) was determined in the field. The hearing of the insect was monitored using hook electrode recordings from an auditory interneuron, which is as sensitive as the hearing organ for frequencies above 16 kHz. The flight path of the bat relative to the insect's position was tracked by recording the echolocation calls with two microphone arrays, and calculating the bat's position from the arrival time differences of the calls at each microphone. The hearing distances ranged from 13 to 30 m. The large variability appeared both between different insects and between different bat approaches to an individual insect. The escape time of the bushcricket, calculated from the detection distance of the insect and the instantaneous flight speed of the bat, ranged from 1.5 to more than 4s. The hearing ranges of bushcrickets suggest that the insect hears the approaching bat long before the bat can detect an echo from the flying insect. PMID:12233766

Adaptive beam-width control of echolocation sounds by CF-FM bats, Rhinolophus ferrumequinum nippon, during prey-capture flight.

PubMed

Matsuta, Naohiro; Hiryu, Shizuko; Fujioka, Emyo; Yamada, Yasufumi; Riquimaroux, Hiroshi; Watanabe, Yoshiaki

2013-04-01

The echolocation sounds of Japanese CF-FM bats (Rhinolophus ferrumequinum nippon) were measured while the bats pursued a moth (Goniocraspidum pryeri) in a flight chamber. Using a 31-channel microphone array system, we investigated how CF-FM bats adjust pulse direction and beam width according to prey position. During the search and approach phases, the horizontal and vertical beam widths were ±22±5 and ±13±5 deg, respectively. When bats entered the terminal phase approximately 1 m from a moth, distinctive evasive flight by G. pryeri was sometimes observed. Simultaneously, the bats broadened the beam widths of some emissions in both the horizontal (44% of emitted echolocation pulses) and vertical planes (71%). The expanded beam widths were ±36±7 deg (horizontal) and ±30±9 deg (vertical). When moths began evasive flight, the tracking accuracy decreased compared with that during the approach phase. However, in 97% of emissions during the terminal phase, the beam width was wider than the misalignment (the angular difference between the pulse and target directions). These findings indicate that bats actively adjust their beam width to retain the moving target within a spatial echolocation window during the final capture stages.

Flight and echolocation behaviour of three vespertilionid bat species while commuting on flyways.

PubMed

Schaub, Andrea; Schnitzler, Hans-Ulrich

2007-12-01

This study compares the flight and echolocation behaviour of three vespertilionid bat species while they commute on flyways. We measured the bats' spatial position relative to vertical background contours and relative to the ground while recording their echolocation behaviour. In Myotis daubentonii, we found a significant influence of spatial context on the position and dimensions of flyways as well as on echolocation behaviour. In gap situations, flyways tended to be narrower and located closer to background structures, flight speeds were lower and the bandwidth of echolocation signals was larger than in edge situations. Differences in background structure did not affect flight and echolocation behaviour. When commuting in the same gap situation flyway positions and dimensions for M. daubentonii and Myotis brandtii were similar but differed from those of Pipistrellus pipistrellus, which were slightly higher and further out than those used by the Myotis species. In M. brandtii, flyway positions and dimensions remained constant over 3 years. We found species-dependent differences in signal structure, but pulse interval and flight speed were similar across all species. The influence of available space on the position of flyways, on flight speed and on echolocation behaviour is discussed.

Echolocation in Oilbirds and swiftlets.

PubMed

Brinkløv, Signe; Fenton, M Brock; Ratcliffe, John M

2013-01-01

The discovery of ultrasonic bat echolocation prompted a wide search for other animal biosonar systems, which yielded, among few others, two avian groups. One, the South American Oilbird (Steatornis caripensis: Caprimulgiformes), is nocturnal and eats fruit. The other is a selection of diurnal, insect-eating swiftlets (species in the genera Aerodramus and Collocalia: Apodidae) from across the Indo-Pacific. Bird echolocation is restricted to lower frequencies audible to humans, implying a system of poorer resolution than the ultrasonic (>20 kHz) biosonar of most bats and toothed whales. As such, bird echolocation has been labeled crude or rudimentary. Yet, echolocation is found in at least 16 extant bird species and has evolved several times in avian lineages. Birds use their syringes to produce broadband click-type biosonar signals that allow them to nest in dark caves and tunnels, probably with less predation pressure. There are ongoing discrepancies about several details of bird echolocation, from signal design to the question about whether echolocation is used during foraging. It remains to be seen if bird echolocation is as sophisticated as that of tongue-clicking rousette bats. Bird echolocation performance appears to be superior to that of blind humans using signals of notable similarity. However, no apparent specializations have been found so far in the birds' auditory system (from middle ear to higher processing centers). The advent of light-weight recording equipment and custom software for examining signals and reconstructing flight paths now provides the potential to study the echolocation behavior of birds in more detail and resolve such issues.

Dynamics of the echolocation beam during prey pursuit in aerial hawking bats.

PubMed

Jakobsen, Lasse; Olsen, Mads Nedergaard; Surlykke, Annemarie

2015-06-30

In the evolutionary arms race between prey and predator, measures and countermeasures continuously evolve to increase survival on both sides. Bats and moths are prime examples. When exposed to intense ultrasound, eared moths perform dramatic escape behaviors. Vespertilionid and rhinolophid bats broaden their echolocation beam in the final stage of pursuit, presumably as a countermeasure to keep evading moths within their "acoustic field of view." In this study, we investigated if dynamic beam broadening is a general property of echolocation when catching moving prey. We recorded three species of emballonurid bats, Saccopteryx bilineata, Saccopteryx leptura, and Rhynchonycteris naso, catching airborne insects in the field. The study shows that S. bilineata and S. leptura maintain a constant beam shape during the entire prey pursuit, whereas R. naso broadens the beam by lowering the peak call frequency from 100 kHz during search and approach to 67 kHz in the buzz. Surprisingly, both Saccopteryx bats emit calls with very high energy throughout the pursuit, up to 60 times more than R. naso and Myotis daubentonii (a similar sized vespertilionid), providing them with as much, or more, peripheral "vision" than the vespertilionids, but ensonifying objects far ahead suggesting more clutter. Thus, beam broadening is not a fundamental property of the echolocation system. However, based on the results, we hypothesize that increased peripheral detection is crucial to all aerial hawking bats in the final stages of prey pursuit and speculate that beam broadening is a feature characterizing more advanced echolocation.

Cloud Model Bat Algorithm

PubMed Central

Zhou, Yongquan; Xie, Jian; Li, Liangliang; Ma, Mingzhi

2014-01-01

Bat algorithm (BA) is a novel stochastic global optimization algorithm. Cloud model is an effective tool in transforming between qualitative concepts and their quantitative representation. Based on the bat echolocation mechanism and excellent characteristics of cloud model on uncertainty knowledge representation, a new cloud model bat algorithm (CBA) is proposed. This paper focuses on remodeling echolocation model based on living and preying characteristics of bats, utilizing the transformation theory of cloud model to depict the qualitative concept: “bats approach their prey.” Furthermore, Lévy flight mode and population information communication mechanism of bats are introduced to balance the advantage between exploration and exploitation. The simulation results show that the cloud model bat algorithm has good performance on functions optimization. PMID:24967425

Development of echolocation calls and neural selectivity for echolocation calls in the pallid bat.

PubMed

Razak, Khaleel A; Fuzessery, Zoltan M

2015-10-01

Studies of birdsongs and neural selectivity for songs have provided important insights into principles of concurrent behavioral and auditory system development. Relatively little is known about mammalian auditory system development in terms of vocalizations or other behaviorally relevant sounds. This review suggests echolocating bats are suitable mammalian model systems to understand development of auditory behaviors. The simplicity of echolocation calls with known behavioral relevance and strong neural selectivity provides a platform to address how natural experience shapes cortical receptive field (RF) mechanisms. We summarize recent studies in the pallid bat that followed development of echolocation calls and cortical processing of such calls. We also discuss similar studies in the mustached bat for comparison. These studies suggest: (1) there are different developmental sensitive periods for different acoustic features of the same vocalization. The underlying basis is the capacity for some components of the RF to be modified independent of others. Some RF computations and maps involved in call processing are present even before the cochlea is mature and well before use of echolocation in flight. Others develop over a much longer time course. (2) Normal experience is required not just for refinement, but also for maintenance, of response properties that develop in an experience independent manner. (3) Experience utilizes millisecond range changes in timing of inhibitory and excitatory RF components as substrates to shape vocalization selectivity. We suggest that bat species and call diversity provide a unique opportunity to address developmental constraints in the evolution of neural mechanisms of vocalization processing. © 2014 Wiley Periodicals, Inc.

Ontogeny of the larynx and flight ability in Jamaican fruit bats (Phyllostomidae) with considerations for the evolution of echolocation.

PubMed

Carter, Richard T; Adams, Rick A

2014-07-01

Echolocating bats have adaptations of the larynx such as hypertrophied intrinsic musculature and calcified or ossified cartilages to support sonar emission. We examined growth and development of the larynx relative to developing flight ability in Jamaican fruit bats to assess how changes in sonar production are coordinated with the onset of flight during ontogeny as a window for understanding the evolutionary relationships between these systems. In addition, we compare the extent of laryngeal calcification in an echolocating shrew species (Sorex vagrans) and the house mouse (Mus musculus), to assess what laryngeal chiropteran adaptations are associated with flight versus echolocation. Individuals were categorized into one of five developmental flight stages (flop, flutter, flap, flight, and adult) determined by drop-tests. Larynges were cleared and stained with alcian blue and alizarin red, or sectioned and stained with hematoxylin and eosin. Our results showed calcification of the cricoid cartilage in bats, represented during the flap stage and this increased significantly in individuals at the flight stage. Thyroid and arytenoid cartilages showed no evidence of calcification and neither cricoid nor thyroid showed significant increases in rate of growth relative to the larynx as a whole. The physiological cross-sectional area of the cricothyroid muscles increased significantly at the flap stage. Shrew larynges showed signs of calcification along the margins of the cricoid and thyroid cartilages, while the mouse larynx did not. These data suggest the larynx of echolocating bats becomes stronger and sturdier in tandem with flight development, indicating possible developmental integration between flight and echolocation. © 2014 Wiley Periodicals, Inc.

Development of echolocation calls and neural selectivity for echolocation calls in the pallid bat

PubMed Central

Razak, Khaleel A.; Fuzessery, Zoltan M.

2014-01-01

Studies of birdsongs and neural selectivity for songs have provided important insights into principles of concurrent behavioral and auditory system development. Relatively little is known about mammalian auditory system development in terms of vocalizations, or other behaviorally relevant sounds. This review suggests echolocating bats are suitable mammalian model systems to understand development of auditory behaviors. The simplicity of echolocation calls with known behavioral relevance and strong neural selectivity provides a platform to address how natural experience shapes cortical receptive field (RF) mechanisms. We summarize recent studies in the pallid bat that followed development of echolocation calls and cortical processing of such calls. We also discuss similar studies in the mustached bat for comparison. These studies suggest: (1) there are different developmental sensitive periods for different acoustic features of the same vocalization. The underlying basis is the capacity for some components of the RF to be modified independent of others. Some RF computations and maps involved in call processing are present even before the cochlea is mature and well before use of echolocation in flight. Others develop over a much longer time course. (2) Normal experience is required not just for refinement, but also for maintenance, of response properties that develop in an experience independent manner. (3) Experience utilizes millisecond range changes in timing of inhibitory and excitatory RF components as substrates to shape vocalization selectivity. We suggest that bat species and call diversity provide a unique opportunity to address developmental constraints in the evolution of neural mechanisms of vocalization processing. PMID:25142131

Hearing diversity in moths confronting a neotropical bat assemblage.

PubMed

Cobo-Cuan, Ariadna; Kössl, Manfred; Mora, Emanuel C

2017-09-01

The tympanal ear is an evolutionary acquisition which helps moths survive predation from bats. The greater diversity of bats and echolocation strategies in the Neotropics compared with temperate zones would be expected to impose different sensory requirements on the neotropical moths. However, even given some variability among moth assemblages, the frequencies of best hearing of moths from different climate zones studied to date have been roughly the same: between 20 and 60 kHz. We have analyzed the auditory characteristics of tympanate moths from Cuba, a neotropical island with high levels of bat diversity and a high incidence of echolocation frequencies above those commonly at the upper limit of moths' hearing sensitivity. Moths of the superfamilies Noctuoidea, Geometroidea and Pyraloidea were examined. Audiograms were determined by non-invasively measuring distortion-product otoacoustic emissions. We also quantified the frequency spectrum of the echolocation sounds to which this moth community is exposed. The hearing ranges of moths in our study showed best frequencies between 36 and 94 kHz. High sensitivity to frequencies above 50 kHz suggests that the auditory sensitivity of moths is suited to the sounds used by sympatric echolocating bat fauna. Biodiversity characterizes predators and prey in the Neotropics, but the bat-moth acoustic interaction keeps spectrally matched.

Global warming alters sound transmission: differential impact on the prey detection ability of echolocating bats

PubMed Central

Luo, Jinhong; Koselj, Klemen; Zsebők, Sándor; Siemers, Björn M.; Goerlitz, Holger R.

2014-01-01

Climate change impacts the biogeography and phenology of plants and animals, yet the underlying mechanisms are little known. Here, we present a functional link between rising temperature and the prey detection ability of echolocating bats. The maximum distance for echo-based prey detection is physically determined by sound attenuation. Attenuation is more pronounced for high-frequency sound, such as echolocation, and is a nonlinear function of both call frequency and ambient temperature. Hence, the prey detection ability, and thus possibly the foraging efficiency, of echolocating bats and susceptible to rising temperatures through climate change. Using present-day climate data and projected temperature rises, we modelled this effect for the entire range of bat call frequencies and climate zones around the globe. We show that depending on call frequency, the prey detection volume of bats will either decrease or increase: species calling above a crossover frequency will lose and species emitting lower frequencies will gain prey detection volume, with crossover frequency and magnitude depending on the local climatic conditions. Within local species assemblages, this may cause a change in community composition. Global warming can thus directly affect the prey detection ability of individual bats and indirectly their interspecific interactions with competitors and prey. PMID:24335559

Global warming alters sound transmission: differential impact on the prey detection ability of echolocating bats.

PubMed

Luo, Jinhong; Koselj, Klemen; Zsebok, Sándor; Siemers, Björn M; Goerlitz, Holger R

2014-02-06

Climate change impacts the biogeography and phenology of plants and animals, yet the underlying mechanisms are little known. Here, we present a functional link between rising temperature and the prey detection ability of echolocating bats. The maximum distance for echo-based prey detection is physically determined by sound attenuation. Attenuation is more pronounced for high-frequency sound, such as echolocation, and is a nonlinear function of both call frequency and ambient temperature. Hence, the prey detection ability, and thus possibly the foraging efficiency, of echolocating bats and susceptible to rising temperatures through climate change. Using present-day climate data and projected temperature rises, we modelled this effect for the entire range of bat call frequencies and climate zones around the globe. We show that depending on call frequency, the prey detection volume of bats will either decrease or increase: species calling above a crossover frequency will lose and species emitting lower frequencies will gain prey detection volume, with crossover frequency and magnitude depending on the local climatic conditions. Within local species assemblages, this may cause a change in community composition. Global warming can thus directly affect the prey detection ability of individual bats and indirectly their interspecific interactions with competitors and prey.

Rapid jamming avoidance in biosonar.

PubMed

Gillam, Erin H; Ulanovsky, Nachum; McCracken, Gary F

2007-03-07

The sonar systems of bats and dolphins are in many ways superior to man-made sonar and radar systems, and considerable effort has been devoted to understanding the signal-processing strategies underlying these capabilities. A major feature determining the efficiency of sonar systems is the sensitivity to noise and jamming signals. Previous studies indicated that echolocating bats may adjust their signal structure to avoid jamming ('jamming avoidance response'; JAR). However, these studies relied on behavioural correlations and not controlled experiments. Here, we provide the first experimental evidence for JAR in bats. We presented bats (Tadarida brasiliensis) with 'playback stimuli' consisting of recorded echolocation calls at one of six frequencies. The bats exhibited a JAR by shifting their call frequency away from the presented playback frequency. When the approaching bats were challenged by an abrupt change in the playback stimulus, they responded by shifting their call frequencies upwards, away from the playback. Interestingly, even bats initially calling below the playback's frequency shifted their frequencies upwards, 'jumping' over the playback frequency. These spectral shifts in the bats' calls occurred often within less than 200 ms, in the first echolocation call emitted after the stimulus switch-suggesting that rapid jamming avoidance is important for the bat.

Echolocation behavior in big brown bats is not impaired after intense broadband noise exposures.

PubMed

Hom, Kelsey N; Linnenschmidt, Meike; Simmons, James A; Simmons, Andrea Megela

2016-10-15

Echolocating bats emit trains of intense ultrasonic biosonar pulses and listen to weaker echoes returning from objects in their environment. Identification and categorization of echoes are crucial for orientation and prey capture. Bats are social animals and often fly in groups in which they are exposed to their own emissions and to those from other bats, as well as to echoes from multiple surrounding objects. Sound pressure levels in these noisy conditions can exceed 110 dB, with no obvious deleterious effects on echolocation performance. Psychophysical experiments show that big brown bats (Eptesicus fuscus) do not experience temporary threshold shifts after exposure to intense broadband ultrasonic noise, but it is not known if they make fine-scale adjustments in their pulse emissions to compensate for any effects of the noise. We investigated whether big brown bats adapt the number, temporal patterning or relative amplitude of their emitted pulses while flying through an acoustically cluttered corridor after exposure to intense broadband noise (frequency range 10-100 kHz; sound exposure level 152 dB). Under these conditions, four bats made no significant changes in navigation errors or in pulse number, timing and amplitude 20 min, 24 h or 48 h after noise exposure. These data suggest that big brown bats remain able to perform difficult echolocation tasks after exposure to ecologically realistic levels of broadband noise. © 2016. Published by The Company of Biologists Ltd.

Calling louder and longer: how bats use biosonar under severe acoustic interference from other bats.

PubMed

Amichai, Eran; Blumrosen, Gaddi; Yovel, Yossi

2015-12-22

Active-sensing systems such as echolocation provide animals with distinct advantages in dark environments. For social animals, however, like many bat species, active sensing can present problems as well: when many individuals emit bio-sonar calls simultaneously, detecting and recognizing the faint echoes generated by one's own calls amid the general cacophony of the group becomes challenging. This problem is often termed 'jamming' and bats have been hypothesized to solve it by shifting the spectral content of their calls to decrease the overlap with the jamming signals. We tested bats' response in situations of extreme interference, mimicking a high density of bats. We played-back bat echolocation calls from multiple speakers, to jam flying Pipistrellus kuhlii bats, simulating a naturally occurring situation of many bats flying in proximity. We examined behavioural and echolocation parameters during search phase and target approach. Under severe interference, bats emitted calls of higher intensity and longer duration, and called more often. Slight spectral shifts were observed but they did not decrease the spectral overlap with jamming signals. We also found that pre-existing inter-individual spectral differences could allow self-call recognition. Results suggest that the bats' response aimed to increase the signal-to-noise ratio and not to avoid spectral overlap. © 2015 The Author(s).

Delayed response and biosonar perception explain movement coordination in trawling bats.

PubMed

Giuggioli, Luca; McKetterick, Thomas J; Holderied, Marc

2015-03-01

Animal coordinated movement interactions are commonly explained by assuming unspecified social forces of attraction, repulsion and alignment with parameters drawn from observed movement data. Here we propose and test a biologically realistic and quantifiable biosonar movement interaction mechanism for echolocating bats based on spatial perceptual bias, i.e. actual sound field, a reaction delay, and observed motor constraints in speed and acceleration. We found that foraging pairs of bats flying over a water surface swapped leader-follower roles and performed chases or coordinated manoeuvres by copying the heading a nearby individual has had up to 500 ms earlier. Our proposed mechanism based on the interplay between sensory-motor constraints and delayed alignment was able to recreate the observed spatial actor-reactor patterns. Remarkably, when we varied model parameters (response delay, hearing threshold and echolocation directionality) beyond those observed in nature, the spatio-temporal interaction patterns created by the model only recreated the observed interactions, i.e. chases, and best matched the observed spatial patterns for just those response delays, hearing thresholds and echolocation directionalities found to be used by bats. This supports the validity of our sensory ecology approach of movement coordination, where interacting bats localise each other by active echolocation rather than eavesdropping.

Tiger moths and the threat of bats: decision-making based on the activity of a single sensory neuron.

PubMed

Ratcliffe, John M; Fullard, James H; Arthur, Benjamin J; Hoy, Ronald R

2009-06-23

Echolocating bats and eared moths are a model system of predator-prey interaction within an almost exclusively auditory world. Through selective pressures from aerial-hawking bats, noctuoid moths have evolved simple ears that contain one to two auditory neurons and function to detect bat echolocation calls and initiate defensive flight behaviours. Among these moths, some chemically defended and mimetic tiger moths also produce ultrasonic clicks in response to bat echolocation calls; these defensive signals are effective warning signals and may interfere with bats' ability to process echoic information. Here, we demonstrate that the activity of a single auditory neuron (the A1 cell) provides sufficient information for the toxic dogbane tiger moth, Cycnia tenera, to decide when to initiate defensive sound production in the face of bats. Thus, despite previous suggestions to the contrary, these moths' only other auditory neuron, the less sensitive A2 cell, is not necessary for initiating sound production. However, we found a positive linear relationship between combined A1 and A2 activity and the number of clicks the dogbane tiger moth produces.

The cochlear size of bats and rodents derived from MRI images and histology.

PubMed

Hsiao, Chun Jen; Jen, Philip Hung-Sun; Wu, Chung Hsin

2015-05-27

From the evolutionary perspective, the ear of each animal species is built for effective processing of the biologically relevant signals used for communication and acoustically guided orientation. Because the sound pulses used by echolocating bats for orientation and rodents for communication are quite different, the basic design of the mammalian auditory system commonly shared by echolocating bats must be specialized in some manner to effectively process their species-specific sounds. The present study examines the difference in the cochlea of these animal species using MRI images and histological techniques. We report here that, although all these animal species share a similar cochlear structure, they vary in their cochlear size and turns. Bats using constant frequency-frequency-modulated pulses (CF-FM bats) and frequency-modulated pulses (FM bats) for echolocation have a larger cochlear size and more cochlear turns than rodents (mice and rats). However, CF-FM bats have the largest cochlear size and most cochlear turns. This difference in cochlear size and turns of these animal species is discussed in relation to their biologically relevant sounds and acoustic behavior.

Echolocation in Oilbirds and swiftlets

PubMed Central

Brinkløv, Signe; Fenton, M. Brock; Ratcliffe, John M.

2013-01-01

The discovery of ultrasonic bat echolocation prompted a wide search for other animal biosonar systems, which yielded, among few others, two avian groups. One, the South American Oilbird (Steatornis caripensis: Caprimulgiformes), is nocturnal and eats fruit. The other is a selection of diurnal, insect-eating swiftlets (species in the genera Aerodramus and Collocalia: Apodidae) from across the Indo-Pacific. Bird echolocation is restricted to lower frequencies audible to humans, implying a system of poorer resolution than the ultrasonic (>20 kHz) biosonar of most bats and toothed whales. As such, bird echolocation has been labeled crude or rudimentary. Yet, echolocation is found in at least 16 extant bird species and has evolved several times in avian lineages. Birds use their syringes to produce broadband click-type biosonar signals that allow them to nest in dark caves and tunnels, probably with less predation pressure. There are ongoing discrepancies about several details of bird echolocation, from signal design to the question about whether echolocation is used during foraging. It remains to be seen if bird echolocation is as sophisticated as that of tongue-clicking rousette bats. Bird echolocation performance appears to be superior to that of blind humans using signals of notable similarity. However, no apparent specializations have been found so far in the birds' auditory system (from middle ear to higher processing centers). The advent of light-weight recording equipment and custom software for examining signals and reconstructing flight paths now provides the potential to study the echolocation behavior of birds in more detail and resolve such issues. PMID:23755019

Dynamics of the echolocation beam during prey pursuit in aerial hawking bats

PubMed Central

Jakobsen, Lasse; Olsen, Mads Nedergaard; Surlykke, Annemarie

2015-01-01

In the evolutionary arms race between prey and predator, measures and countermeasures continuously evolve to increase survival on both sides. Bats and moths are prime examples. When exposed to intense ultrasound, eared moths perform dramatic escape behaviors. Vespertilionid and rhinolophid bats broaden their echolocation beam in the final stage of pursuit, presumably as a countermeasure to keep evading moths within their “acoustic field of view.” In this study, we investigated if dynamic beam broadening is a general property of echolocation when catching moving prey. We recorded three species of emballonurid bats, Saccopteryx bilineata, Saccopteryx leptura, and Rhynchonycteris naso, catching airborne insects in the field. The study shows that S. bilineata and S. leptura maintain a constant beam shape during the entire prey pursuit, whereas R. naso broadens the beam by lowering the peak call frequency from 100 kHz during search and approach to 67 kHz in the buzz. Surprisingly, both Saccopteryx bats emit calls with very high energy throughout the pursuit, up to 60 times more than R. naso and Myotis daubentonii (a similar sized vespertilionid), providing them with as much, or more, peripheral “vision” than the vespertilionids, but ensonifying objects far ahead suggesting more clutter. Thus, beam broadening is not a fundamental property of the echolocation system. However, based on the results, we hypothesize that increased peripheral detection is crucial to all aerial hawking bats in the final stages of prey pursuit and speculate that beam broadening is a feature characterizing more advanced echolocation. PMID:26080398

Dynamic Echo Information Guides Flight in the Big Brown Bat

PubMed Central

Warnecke, Michaela; Lee, Wu-Jung; Krishnan, Anand; Moss, Cynthia F.

2016-01-01

Animals rely on sensory feedback from their environment to guide locomotion. For instance, visually guided animals use patterns of optic flow to control their velocity and to estimate their distance to objects (e.g., Srinivasan et al., 1991, 1996). In this study, we investigated how acoustic information guides locomotion of animals that use hearing as a primary sensory modality to orient and navigate in the dark, where visual information is unavailable. We studied flight and echolocation behaviors of big brown bats as they flew under infrared illumination through a corridor with walls constructed from a series of individual vertical wooden poles. The spacing between poles on opposite walls of the corridor was experimentally manipulated to create dense/sparse and balanced/imbalanced spatial structure. The bats’ flight trajectories and echolocation signals were recorded with high-speed infrared motion-capture cameras and ultrasound microphones, respectively. As bats flew through the corridor, successive biosonar emissions returned cascades of echoes from the walls of the corridor. The bats flew through the center of the corridor when the pole spacing on opposite walls was balanced and closer to the side with wider pole spacing when opposite walls had an imbalanced density. Moreover, bats produced shorter duration echolocation calls when they flew through corridors with smaller spacing between poles, suggesting that clutter density influences features of the bat’s sonar signals. Flight speed and echolocation call rate did not, however, vary with dense and sparse spacing between the poles forming the corridor walls. Overall, these data demonstrate that bats adapt their flight and echolocation behavior dynamically when flying through acoustically complex environments. PMID:27199690

The anti-bat strategy of ultrasound absorption: the wings of nocturnal moths (Bombycoidea: Saturniidae) absorb more ultrasound than the wings of diurnal moths (Chalcosiinae: Zygaenoidea: Zygaenidae).

PubMed

Ntelezos, Athanasios; Guarato, Francesco; Windmill, James F C

2017-01-15

The selection pressure from echolocating bats has driven the development of a diverse range of anti-bat strategies in insects. For instance, several studies have proposed that the wings of some moths absorb a large portion of the sound energy contained in a bat's ultrasonic cry; as a result, the bat receives a dampened echo, and the moth becomes invisible to the bat. To test the hypothesis that greater exposure to bat predation drives the development of higher ultrasound absorbance, we used a small reverberation chamber to measure the ultrasound absorbance of the wings of nocturnal (Bombycoidea: Saturniidae) and diurnal moths (Chalcosiinae: Zygaenoidea: Zygaenidae). The absorption factor of the nocturnal saturniids peaks significantly higher than the absorption factor of the diurnal chalcosiines. However, the wings of the chalcosiines absorb more ultrasound than the wings of some diurnal butterflies. Following a phylogenetic analysis on the character state of diurnality/ nocturnality in the Zygaenidae, we propose that diurnality in the Chalcosiinae is plesiomorphic (retained); hence, the absorbance of their wings is probably not a vestigial trait from an ancestral, nocturnal form but an adaptation to bat activity that overlaps their own. On a within-species level, females of the saturniids Argema mittrei and Samia cynthia ricini have significantly higher absorption factors than the males. In the female S. c. ricini, the higher absorption factor corresponds to a detection distance by bats that is at best 20-30% shorter than that of the male. © 2017. Published by The Company of Biologists Ltd.

The anti-bat strategy of ultrasound absorption: the wings of nocturnal moths (Bombycoidea: Saturniidae) absorb more ultrasound than the wings of diurnal moths (Chalcosiinae: Zygaenoidea: Zygaenidae)

PubMed Central

Guarato, Francesco; Windmill, James F. C.

2017-01-01

ABSTRACT The selection pressure from echolocating bats has driven the development of a diverse range of anti-bat strategies in insects. For instance, several studies have proposed that the wings of some moths absorb a large portion of the sound energy contained in a bat's ultrasonic cry; as a result, the bat receives a dampened echo, and the moth becomes invisible to the bat. To test the hypothesis that greater exposure to bat predation drives the development of higher ultrasound absorbance, we used a small reverberation chamber to measure the ultrasound absorbance of the wings of nocturnal (Bombycoidea: Saturniidae) and diurnal moths (Chalcosiinae: Zygaenoidea: Zygaenidae). The absorption factor of the nocturnal saturniids peaks significantly higher than the absorption factor of the diurnal chalcosiines. However, the wings of the chalcosiines absorb more ultrasound than the wings of some diurnal butterflies. Following a phylogenetic analysis on the character state of diurnality/ nocturnality in the Zygaenidae, we propose that diurnality in the Chalcosiinae is plesiomorphic (retained); hence, the absorbance of their wings is probably not a vestigial trait from an ancestral, nocturnal form but an adaptation to bat activity that overlaps their own. On a within-species level, females of the saturniids Argema mittrei and Samia cynthia ricini have significantly higher absorption factors than the males. In the female S. c. ricini, the higher absorption factor corresponds to a detection distance by bats that is at best 20-30% shorter than that of the male. PMID:27913454

Temporal tuning in the bat auditory cortex is sharper when studied with natural echolocation sequences.

PubMed

Beetz, M Jerome; Hechavarría, Julio C; Kössl, Manfred

2016-06-30

Precise temporal coding is necessary for proper acoustic analysis. However, at cortical level, forward suppression appears to limit the ability of neurons to extract temporal information from natural sound sequences. Here we studied how temporal processing can be maintained in the bats' cortex in the presence of suppression evoked by natural echolocation streams that are relevant to the bats' behavior. We show that cortical neurons tuned to target-distance actually profit from forward suppression induced by natural echolocation sequences. These neurons can more precisely extract target distance information when they are stimulated with natural echolocation sequences than during stimulation with isolated call-echo pairs. We conclude that forward suppression does for time domain tuning what lateral inhibition does for selectivity forms such as auditory frequency tuning and visual orientation tuning. When talking about cortical processing, suppression should be seen as a mechanistic tool rather than a limiting element.

From the ultrasonic to the infrared: molecular evolution and the sensory biology of bats

PubMed Central

Jones, Gareth; Teeling, Emma C.; Rossiter, Stephen J.

2013-01-01

Great advances have been made recently in understanding the genetic basis of the sensory biology of bats. Research has focused on the molecular evolution of candidate sensory genes, genes with known functions [e.g., olfactory receptor (OR) genes] and genes identified from mutations associated with sensory deficits (e.g., blindness and deafness). For example, the FoxP2 gene, underpinning vocal behavior and sensorimotor coordination, has undergone diversification in bats, while several genes associated with audition show parallel amino acid substitutions in unrelated lineages of echolocating bats and, in some cases, in echolocating dolphins, representing a classic case of convergent molecular evolution. Vision genes encoding the photopigments rhodopsin and the long-wave sensitive opsin are functional in bats, while that encoding the short-wave sensitive opsin has lost functionality in rhinolophoid bats using high-duty cycle laryngeal echolocation, suggesting a sensory trade-off between investment in vision and echolocation. In terms of olfaction, bats appear to have a distinctive OR repertoire compared with other mammals, and a gene involved in signal transduction in the vomeronasal system has become non-functional in most bat species. Bitter taste receptors appear to have undergone a “birth-and death” evolution involving extensive gene duplication and loss, unlike genes coding for sweet and umami tastes that show conservation across most lineages but loss in vampire bats. Common vampire bats have also undergone adaptations for thermoperception, via alternative splicing resulting in the evolution of a novel heat-sensitive channel. The future for understanding the molecular basis of sensory biology is promising, with great potential for comparative genomic analyses, studies on gene regulation and expression, exploration of the role of alternative splicing in the generation of proteomic diversity, and linking genetic mechanisms to behavioral consequences. PMID:23755015

Does similarity in call structure or foraging ecology explain interspecific information transfer in wild Myotis bats?

PubMed

Hügel, Theresa; van Meir, Vincent; Muñoz-Meneses, Amanda; Clarin, B-Markus; Siemers, Björn M; Goerlitz, Holger R

2017-01-01

Animals can gain important information by attending to the signals and cues of other animals in their environment, with acoustic information playing a major role in many taxa. Echolocation call sequences of bats contain information about the identity and behaviour of the sender which is perceptible to close-by receivers. Increasing evidence supports the communicative function of echolocation within species, yet data about its role for interspecific information transfer is scarce. Here, we asked which information bats extract from heterospecific echolocation calls during foraging. In three linked playback experiments, we tested in the flight room and field if foraging Myotis bats approached the foraging call sequences of conspecifics and four heterospecifics that were similar in acoustic call structure only (acoustic similarity hypothesis), in foraging ecology only (foraging similarity hypothesis), both, or none. Compared to the natural prey capture rate of 1.3 buzzes per minute of bat activity, our playbacks of foraging sequences with 23-40 buzzes/min simulated foraging patches with significantly higher profitability. In the flight room, M. capaccinii only approached call sequences of conspecifics and of the heterospecific M. daubentonii with similar acoustics and foraging ecology. In the field, M. capaccinii and M. daubentonii only showed a weak positive response to those two species. Our results confirm information transfer across species boundaries and highlight the importance of context on the studied behaviour, but cannot resolve whether information transfer in trawling Myotis is based on acoustic similarity only or on a combination of similarity in acoustics and foraging ecology. Animals transfer information, both voluntarily and inadvertently, and within and across species boundaries. In echolocating bats, acoustic call structure and foraging ecology are linked, making echolocation calls a rich source of information about species identity, ecology and activity of the sender, which receivers might exploit to find profitable foraging grounds. We tested in three lab and field experiments if information transfer occurs between bat species and if bats obtain information about ecology from echolocation calls. Myotis capaccinii/daubentonii bats approached call playbacks, but only those from con- and heterospecifics with similar call structure and foraging ecology, confirming interspecific information transfer. Reactions differed between lab and field, emphasising situation-dependent differences in animal behaviour, the importance of field research, and the need for further studies on the underlying mechanism of information transfer and the relative contributions of acoustic and ecological similarity.

How Nectar-Feeding Bats Localize their Food: Echolocation Behavior of Leptonycteris yerbabuenae Approaching Cactus Flowers

PubMed Central

Koblitz, Jens C.; Fleming, Theodore H.; Medellín, Rodrigo A.; Kalko, Elisabeth K. V.; Schnitzler, Hans-Ulrich; Tschapka, Marco

2016-01-01

Nectar-feeding bats show morphological, physiological, and behavioral adaptations for feeding on nectar. How they find and localize flowers is still poorly understood. While scent cues alone allow no precise localization of a floral target, the spatial properties of flower echoes are very precise and could play a major role, particularly at close range. The aim of this study is to understand the role of echolocation for classification and localization of flowers. We compared the approach behavior of Leptonycteris yerbabuenae to flowers of a columnar cactus, Pachycereus pringlei, to that to an acrylic hollow hemisphere that is acoustically conspicuous to bats, but has different acoustic properties and, contrary to the cactus flower, present no scent. For recording the flight and echolocation behaviour we used two infrared video cameras under stroboscopic illumination synchronized with ultrasound recordings. During search flights all individuals identified both targets as a possible food source and initiated an approach flight; however, they visited only the cactus flower. In experiments with the acrylic hemisphere bats aborted the approach at ca. 40–50 cm. In the last instant before the flower visit the bats emitted a long terminal group of 10–20 calls. This is the first report of this behaviour for a nectar-feeding bat. Our findings suggest that L. yerbabuenae use echolocation for classification and localization of cactus flowers and that the echo-acoustic characteristics of the flower guide the bats directly to the flower opening. PMID:27684373

Broadband noise exposure does not affect hearing sensitivity in big brown bats (Eptesicus fuscus).

PubMed

Simmons, Andrea Megela; Hom, Kelsey N; Warnecke, Michaela; Simmons, James A

2016-04-01

In many vertebrates, exposure to intense sounds under certain stimulus conditions can induce temporary threshold shifts that reduce hearing sensitivity. Susceptibility to these hearing losses may reflect the relatively quiet environments in which most of these species have evolved. Echolocating big brown bats (Eptesicus fuscus) live in extremely intense acoustic environments in which they navigate and forage successfully, both alone and in company with other bats. We hypothesized that bats may have evolved a mechanism to minimize noise-induced hearing losses that otherwise could impair natural echolocation behaviors. The hearing sensitivity of seven big brown bats was measured in active echolocation and passive hearing tasks, before and after exposure to broadband noise spanning their audiometric range (10-100 kHz, 116 dB SPL re. 20 µPa rms, 1 h duration; sound exposure level 152 dB). Detection thresholds measured 20 min, 2 h or 24 h after exposure did not vary significantly from pre-exposure thresholds or from thresholds in control (sham exposure) conditions. These results suggest that big brown bats may be less susceptible to temporary threshold shifts than are other terrestrial mammals after exposure to similarly intense broadband sounds. These experiments provide fertile ground for future research on possible mechanisms employed by echolocating bats to minimize hearing losses while orienting effectively in noisy biological soundscapes. © 2016. Published by The Company of Biologists Ltd.

Recording animal vocalizations from a UAV: bat echolocation during roost re-entry.

PubMed

Kloepper, Laura N; Kinniry, Morgan

2018-05-17

Unmanned aerial vehicles (UAVs) are rising in popularity for wildlife monitoring, but direct recordings of animal vocalizations have not yet been accomplished, likely due to the noise generated by the UAV. Echolocating bats, especially Tadarida brasiliensis, are good candidates for UAV recording due to their high-speed, high-altitude flight. Here, we use a UAV to record the signals of bats during morning roost re-entry. We designed a UAV to block the noise of the propellers from the receiving microphone, and report on the characteristics of bioacoustic recordings from a UAV. We report the first published characteristics of echolocation signals from bats during group flight and cave re-entry. We found changes in inter-individual time-frequency shape, suggesting that bats may use differences in call design when sensing in complex groups. Furthermore, our first documented successful recordings of animals in their natural habitat demonstrate that UAVs can be important tools for bioacoustic monitoring, and we discuss the ethical considerations for such monitoring.

Calling louder and longer: how bats use biosonar under severe acoustic interference from other bats

PubMed Central

Amichai, Eran; Blumrosen, Gaddi; Yovel, Yossi

2015-01-01

Active-sensing systems such as echolocation provide animals with distinct advantages in dark environments. For social animals, however, like many bat species, active sensing can present problems as well: when many individuals emit bio-sonar calls simultaneously, detecting and recognizing the faint echoes generated by one's own calls amid the general cacophony of the group becomes challenging. This problem is often termed ‘jamming’ and bats have been hypothesized to solve it by shifting the spectral content of their calls to decrease the overlap with the jamming signals. We tested bats’ response in situations of extreme interference, mimicking a high density of bats. We played-back bat echolocation calls from multiple speakers, to jam flying Pipistrellus kuhlii bats, simulating a naturally occurring situation of many bats flying in proximity. We examined behavioural and echolocation parameters during search phase and target approach. Under severe interference, bats emitted calls of higher intensity and longer duration, and called more often. Slight spectral shifts were observed but they did not decrease the spectral overlap with jamming signals. We also found that pre-existing inter-individual spectral differences could allow self-call recognition. Results suggest that the bats’ response aimed to increase the signal-to-noise ratio and not to avoid spectral overlap. PMID:26702045

Bat detective-Deep learning tools for bat acoustic signal detection.

PubMed

Mac Aodha, Oisin; Gibb, Rory; Barlow, Kate E; Browning, Ella; Firman, Michael; Freeman, Robin; Harder, Briana; Kinsey, Libby; Mead, Gary R; Newson, Stuart E; Pandourski, Ivan; Parsons, Stuart; Russ, Jon; Szodoray-Paradi, Abigel; Szodoray-Paradi, Farkas; Tilova, Elena; Girolami, Mark; Brostow, Gabriel; Jones, Kate E

2018-03-01

Passive acoustic sensing has emerged as a powerful tool for quantifying anthropogenic impacts on biodiversity, especially for echolocating bat species. To better assess bat population trends there is a critical need for accurate, reliable, and open source tools that allow the detection and classification of bat calls in large collections of audio recordings. The majority of existing tools are commercial or have focused on the species classification task, neglecting the important problem of first localizing echolocation calls in audio which is particularly problematic in noisy recordings. We developed a convolutional neural network based open-source pipeline for detecting ultrasonic, full-spectrum, search-phase calls produced by echolocating bats. Our deep learning algorithms were trained on full-spectrum ultrasonic audio collected along road-transects across Europe and labelled by citizen scientists from www.batdetective.org. When compared to other existing algorithms and commercial systems, we show significantly higher detection performance of search-phase echolocation calls with our test sets. As an example application, we ran our detection pipeline on bat monitoring data collected over five years from Jersey (UK), and compared results to a widely-used commercial system. Our detection pipeline can be used for the automatic detection and monitoring of bat populations, and further facilitates their use as indicator species on a large scale. Our proposed pipeline makes only a small number of bat specific design decisions, and with appropriate training data it could be applied to detecting other species in audio. A crucial novelty of our work is showing that with careful, non-trivial, design and implementation considerations, state-of-the-art deep learning methods can be used for accurate and efficient monitoring in audio.

Bat detective—Deep learning tools for bat acoustic signal detection

PubMed Central

Barlow, Kate E.; Firman, Michael; Freeman, Robin; Harder, Briana; Kinsey, Libby; Mead, Gary R.; Newson, Stuart E.; Pandourski, Ivan; Russ, Jon; Szodoray-Paradi, Abigel; Tilova, Elena; Girolami, Mark; Jones, Kate E.

2018-01-01

Passive acoustic sensing has emerged as a powerful tool for quantifying anthropogenic impacts on biodiversity, especially for echolocating bat species. To better assess bat population trends there is a critical need for accurate, reliable, and open source tools that allow the detection and classification of bat calls in large collections of audio recordings. The majority of existing tools are commercial or have focused on the species classification task, neglecting the important problem of first localizing echolocation calls in audio which is particularly problematic in noisy recordings. We developed a convolutional neural network based open-source pipeline for detecting ultrasonic, full-spectrum, search-phase calls produced by echolocating bats. Our deep learning algorithms were trained on full-spectrum ultrasonic audio collected along road-transects across Europe and labelled by citizen scientists from www.batdetective.org. When compared to other existing algorithms and commercial systems, we show significantly higher detection performance of search-phase echolocation calls with our test sets. As an example application, we ran our detection pipeline on bat monitoring data collected over five years from Jersey (UK), and compared results to a widely-used commercial system. Our detection pipeline can be used for the automatic detection and monitoring of bat populations, and further facilitates their use as indicator species on a large scale. Our proposed pipeline makes only a small number of bat specific design decisions, and with appropriate training data it could be applied to detecting other species in audio. A crucial novelty of our work is showing that with careful, non-trivial, design and implementation considerations, state-of-the-art deep learning methods can be used for accurate and efficient monitoring in audio. PMID:29518076

Drinking and Flying: Does Alcohol Consumption Affect the Flight and Echolocation Performance of Phyllostomid Bats?

PubMed Central

Orbach, Dara N.; Veselka, Nina; Dzal, Yvonne; Lazure, Louis; Fenton, M. Brock

2010-01-01

Background In the wild, frugivorous and nectarivorous bats often eat fermenting fruits and nectar, and thus may consume levels of ethanol that could induce inebriation. To understand if consumption of ethanol by bats alters their access to food and general survival requires examination of behavioural responses to its ingestion, as well as assessment of interspecific variation in those responses. We predicted that bats fed ethanol would show impaired flight and echolocation behaviour compared to bats fed control sugar water, and that there would be behavioural differences among species. Methodology/Principal Findings We fed wild caught Artibeus jamaicensis, A. lituratus, A. phaeotis, Carollia sowelli, Glossophaga soricina, and Sturnira lilium (Chiroptera, Phyllostomidae) sugar water (44 g of table sugar in 500 ml of water) or sugar water with ethanol before challenging them to fly through an obstacle course while we simultaneously recorded their echolocation calls. We used bat saliva, a non-invasive proxy, to measure blood ethanol concentrations ranging from 0 to >0.3% immediately before flight trials. Flight performance and echolocation behaviour were not significantly affected by consumption of ethanol, but species differed in their blood alcohol concentrations after consuming it. Conclusions/Significance The bats we studied display a tolerance for ethanol that could have ramifications for the adaptive radiation of frugivorous and nectarivorous bats by allowing them to use ephemeral food resources over a wide span of time. By sampling across phyllostomid genera, we show that patterns of apparent ethanol tolerance in New World bats are broad, and thus may have been an important early step in the evolution of frugivory and nectarivory in these animals. PMID:20126552

Echolocating Big Brown Bats, Eptesicus fuscus, Modulate Pulse Intervals to Overcome Range Ambiguity in Cluttered Surroundings

PubMed Central

Wheeler, Alyssa R.; Fulton, Kara A.; Gaudette, Jason E.; Simmons, Ryan A.; Matsuo, Ikuo; Simmons, James A.

2016-01-01

Big brown bats (Eptesicus fuscus) emit trains of brief, wideband frequency-modulated (FM) echolocation sounds and use echoes of these sounds to orient, find insects, and guide flight through vegetation. They are observed to emit sounds that alternate between short and long inter-pulse intervals (IPIs), forming sonar sound groups. The occurrence of these strobe groups has been linked to flight in cluttered acoustic environments, but how exactly bats use sonar sound groups to orient and navigate is still a mystery. Here, the production of sound groups during clutter navigation was examined. Controlled flight experiments were conducted where the proximity of the nearest obstacles was systematically decreased while the extended scene was kept constant. Four bats flew along a corridor of varying widths (100, 70, and 40 cm) bounded by rows of vertically hanging plastic chains while in-flight echolocation calls were recorded. Bats shortened their IPIs for more rapid spatial sampling and also grouped their sounds more tightly when flying in narrower corridors. Bats emitted echolocation calls with progressively shorter IPIs over the course of a flight, and began their flights by emitting shorter starting IPI calls when clutter was denser. The percentage of sound groups containing 3 or more calls increased with increasing clutter proximity. Moreover, IPI sequences having internal structure become more pronounced when corridor width narrows. A novel metric for analyzing the temporal organization of sound sequences was developed, and the results indicate that the time interval between echolocation calls depends heavily on the preceding time interval. The occurrence of specific IPI patterns were dependent upon clutter, which suggests that sonar sound grouping may be an adaptive strategy for coping with pulse-echo ambiguity in cluttered surroundings. PMID:27445723

Delayed Response and Biosonar Perception Explain Movement Coordination in Trawling Bats

PubMed Central

Giuggioli, Luca; McKetterick, Thomas J.; Holderied, Marc

2015-01-01

Animal coordinated movement interactions are commonly explained by assuming unspecified social forces of attraction, repulsion and alignment with parameters drawn from observed movement data. Here we propose and test a biologically realistic and quantifiable biosonar movement interaction mechanism for echolocating bats based on spatial perceptual bias, i.e. actual sound field, a reaction delay, and observed motor constraints in speed and acceleration. We found that foraging pairs of bats flying over a water surface swapped leader-follower roles and performed chases or coordinated manoeuvres by copying the heading a nearby individual has had up to 500 ms earlier. Our proposed mechanism based on the interplay between sensory-motor constraints and delayed alignment was able to recreate the observed spatial actor-reactor patterns. Remarkably, when we varied model parameters (response delay, hearing threshold and echolocation directionality) beyond those observed in nature, the spatio-temporal interaction patterns created by the model only recreated the observed interactions, i.e. chases, and best matched the observed spatial patterns for just those response delays, hearing thresholds and echolocation directionalities found to be used by bats. This supports the validity of our sensory ecology approach of movement coordination, where interacting bats localise each other by active echolocation rather than eavesdropping. PMID:25811627

Classification of communication signals of the little brown bat

NASA Astrophysics Data System (ADS)

Melendez, Karla V.; Jones, Douglas L.; Feng, Albert S.

2005-09-01

Little brown bats, Myotis lucifugus, are known for their ability to echolocate and utilize their echolocation system to navigate, locate, and identify prey. Their echolocation signals have been characterized in detail, but their communication signals are poorly understood despite their widespread use during the social interactions. The goal of this study was to characterize the communication signals of little brown bats. Sound recordings were made overnight on five individual bats (housed separately from a large group of captive bats) for 7 nights, using a Pettersson ultrasound detector D240x bat detector and Nagra ARES-BB digital recorder. The spectral and temporal characteristics of recorded sounds were first analyzed using BATSOUND software from Pettersson. Sounds were first classified by visual observation of calls' temporal pattern and spectral composition, and later using an automatic classification scheme based on multivariate statistical parameters in MATLAB. Human- and machine-based analysis revealed five discrete classes of bat's communication signals: downward frequency-modulated calls, constant frequency calls, broadband noise bursts, broadband chirps, and broadband click trains. Future studies will focus on analysis of calls' spectrotemporal modulations to discriminate any subclasses that may exist. [Research supported by Grant R01-DC-04998 from the National Institute for Deafness and Communication Disorders.

Light-emitting diode street lights reduce last-ditch evasive manoeuvres by moths to bat echolocation calls

PubMed Central

Wakefield, Andrew; Stone, Emma L.; Jones, Gareth; Harris, Stephen

2015-01-01

The light-emitting diode (LED) street light market is expanding globally, and it is important to understand how LED lights affect wildlife populations. We compared evasive flight responses of moths to bat echolocation calls experimentally under LED-lit and -unlit conditions. Significantly, fewer moths performed ‘powerdive’ flight manoeuvres in response to bat calls (feeding buzz sequences from Nyctalus spp.) under an LED street light than in the dark. LED street lights reduce the anti-predator behaviour of moths, shifting the balance in favour of their predators, aerial hawking bats. PMID:26361558

Echolocating bats rely on audiovocal feedback to adapt sonar signal design.

PubMed

Luo, Jinhong; Moss, Cynthia F

2017-10-10

Many species of bat emit acoustic signals and use information carried by echoes reflecting from nearby objects to navigate and forage. It is widely documented that echolocating bats adjust the features of sonar calls in response to echo feedback; however, it remains unknown whether audiovocal feedback contributes to sonar call design. Audiovocal feedback refers to the monitoring of one's own vocalizations during call production and has been intensively studied in nonecholocating animals. Audiovocal feedback not only is a necessary component of vocal learning but also guides the control of the spectro-temporal structure of vocalizations. Here, we show that audiovocal feedback is directly involved in the echolocating bat's control of sonar call features. As big brown bats tracked targets from a stationary position, we played acoustic jamming signals, simulating calls of another bat, timed to selectively perturb audiovocal feedback or echo feedback. We found that the bats exhibited the largest call-frequency adjustments when the jamming signals occurred during vocal production. By contrast, bats did not show sonar call-frequency adjustments when the jamming signals coincided with the arrival of target echoes. Furthermore, bats rapidly adapted sonar call design in the first vocalization following the jamming signal, revealing a response latency in the range of 66 to 94 ms. Thus, bats, like songbirds and humans, rely on audiovocal feedback to structure sonar signal design.

Bat use of a high-plains urban wildlife refuge

USGS Publications Warehouse

Everette, A.L.; O'Shea, T.J.; Ellison, L.E.; Stone, L.A.; McCance, J.L.

2001-01-01

Bats are significant components of mammalian diversity and in many areas are of management concern. However, little attention has been given to bats in urban or prairie landscapes. In 1997 and 1998, we determined species richness, relative abundance, roosting habits, and echolocation activity of bats at Rocky Mountain Arsenal National Wildlife Refuge (RMA), the largest urban unit in the United States refuge system, located on the high plains near Denver, Colorado. An inventory using mist nets revealed 3 species foraging at this site: big brown bats (Eptesicus fuscus), hoary bats (Lasiurus cinereus), and silver-haired bats (Lasionycteris noctivagans). Big brown bats comprised 86% of captures (n=176). This pattern was consistent with continental-scale predictions of bat species richness and evenness based on availability of potential roosts. Relative abundance based on captures was similar to that revealed by echolocation detector surveys, except that the latter revealed the likely presence of at least 2 additional species (Myotis spp. and red bats [Lasiurus borealis]). Echolocation activity was significantly greater (P=0.009) in areas with tree or water habitat edges than in open prairie, suggesting that maintaining such features is important for bats. Big brown bats commuted greater distances (9.2-18.8 km) from roosts in urban core areas to foraging sites on the refuge than typically reported for this species elsewhere, emphasizing the value of the site to these bats. Urban refuges can provide habitat of importance to bat populations, but may be characterized by abundant bats that roost in buildings if a variety of other kinds of roosting habitats are unavailable.

Variability in echolocation call intensity in a community of horseshoe bats: a role for resource partitioning or communication?

PubMed

Schuchmann, Maike; Siemers, Björn M

2010-09-17

Only recently data on bat echolocation call intensities is starting to accumulate. Yet, intensity is an ecologically crucial parameter, as it determines the extent of the bats' perceptual space and, specifically, prey detection distance. Interspecifically, we thus asked whether sympatric, congeneric bat species differ in call intensities and whether differences play a role for niche differentiation. Specifically, we investigated whether R. mehelyi that calls at a frequency clearly above what is predicted by allometry, compensates for frequency-dependent loss in detection distance by using elevated call intensity. Maximum echolocation call intensities might depend on body size or condition and thus be used as an honest signal of quality for intraspecific communication. We for the first time investigated whether a size-intensity relation is present in echolocating bats. We measured maximum call intensities and frequencies for all five European horseshoe bat species. Maximum intensity differed among species largely due to R. euryale. Furthermore, we found no compensation for frequency-dependent loss in detection distance in R. mehelyi. Intraspecifically, there is a negative correlation between forearm lengths and intensity in R. euryale and a trend for a negative correlation between body condition index and intensity in R. ferrumequinum. In R. hipposideros, females had 8 dB higher intensities than males. There were no correlations with body size or sex differences and intensity for the other species. Based on call intensity and frequency measurements, we estimated echolocation ranges for our study community. These suggest that intensity differences result in different prey detection distances and thus likely play some role for resource access. It is interesting and at first glance counter-intuitive that, where a correlation was found, smaller bats called louder than large individuals. Such negative relationship between size or condition and vocal amplitude may indicate an as yet unknown physiological or sexual selection pressure.

Variability in Echolocation Call Intensity in a Community of Horseshoe Bats: A Role for Resource Partitioning or Communication?

PubMed Central

Schuchmann, Maike; Siemers, Björn M.

2010-01-01

Background Only recently data on bat echolocation call intensities is starting to accumulate. Yet, intensity is an ecologically crucial parameter, as it determines the extent of the bats' perceptual space and, specifically, prey detection distance. Interspecifically, we thus asked whether sympatric, congeneric bat species differ in call intensities and whether differences play a role for niche differentiation. Specifically, we investigated whether R. mehelyi that calls at a frequency clearly above what is predicted by allometry, compensates for frequency-dependent loss in detection distance by using elevated call intensity. Maximum echolocation call intensities might depend on body size or condition and thus be used as an honest signal of quality for intraspecific communication. We for the first time investigated whether a size-intensity relation is present in echolocating bats. Methodology/Principal Findings We measured maximum call intensities and frequencies for all five European horseshoe bat species. Maximum intensity differed among species largely due to R. euryale. Furthermore, we found no compensation for frequency-dependent loss in detection distance in R. mehelyi. Intraspecifically, there is a negative correlation between forearm lengths and intensity in R. euryale and a trend for a negative correlation between body condition index and intensity in R. ferrumequinum. In R. hipposideros, females had 8 dB higher intensities than males. There were no correlations with body size or sex differences and intensity for the other species. Conclusions/Significance Based on call intensity and frequency measurements, we estimated echolocation ranges for our study community. These suggest that intensity differences result in different prey detection distances and thus likely play some role for resource access. It is interesting and at first glance counter-intuitive that, where a correlation was found, smaller bats called louder than large individuals. Such negative relationship between size or condition and vocal amplitude may indicate an as yet unknown physiological or sexual selection pressure. PMID:20862252

Extremely high frequency sensitivity in a 'simple' ear.

PubMed

Moir, Hannah M; Jackson, Joseph C; Windmill, James F C

2013-08-23

An evolutionary war is being played out between the bat, which uses ultrasonic calls to locate insect prey, and the moth, which uses microscale ears to listen for the approaching bat. While the highest known frequency of bat echolocation calls is 212 kHz, the upper limit of moth hearing is considered much lower. Here, we show that the greater wax moth, Galleria mellonella, is capable of hearing ultrasonic frequencies approaching 300 kHz; the highest frequency sensitivity of any animal. With auditory frequency sensitivity that is unprecedented in the animal kingdom, the greater wax moth is ready and armed for any echolocation call adaptations made by the bat in the on-going bat-moth evolutionary war.

Morphology suggests noseleaf and pinnae cooperate to enhance bat echolocation.

PubMed

Kuc, Roman

2010-11-01

A protruding noseleaf and concave pinna structures suggest that some bats may use these to enhance their echolocation capabilities. This paper considers two possible mechanisms that each exploit the combination of direct and delayed acoustic paths to achieve more complex emission or sensitivity echolocation patterns. The first is an emission mechanism, in which the protruding noseleaf vibrates to emit sound in both the forward and backward directions, and pinna structures reflect the backward emission to enhance the forward beam. The second is a reception mechanism, which has a direct echo path to the ear canal and a delayed path involving pinna structures reflecting onto the noseleaf and then into the ear canal. A model using Davis' Round-eared Bat illustrates that such direct and delayed acoustic paths provide target elevation cues. The model demonstrates the delayed pinna component can increase the on-axis emission strength, narrow the beam width, and sculpt frequency-dependent beam patterns useful for echolocation.

Bats in Agroecosytems around California's Central Coast

NASA Astrophysics Data System (ADS)

Wayne, A.

2014-12-01

Bats in agroecosystems around California's Central Coast: A full quarter of California's land area is farmland. Crops account for 32.5 billion of California's GDP. Insect control is a big problem for farmers, and California bats eat only insects, saving farmers an estimated 3 to $53 billion a year. As farmers maximize crop yield, they use more pesticides, herbicides, and fertilizers, which contaminate runoff streams that bats drink from. Also, pesticide use kills bats' sole food source: insects. My research objective was to find out how farm management practices and landscape complexity affect bat diversity and activity, and to see which one affects bat activity more. We monitored 18 sites, including conventional, organic, and low and high-complexity landscapes. We noted more bat activity at sites with high complexity landscapes and organic practices than at sites with either low-complexity landscapes or conventional farming practices. I captured and processed bats and recorded data. I also classified insects collected from light traps. I learned how to handle bats and measure forearm length and weight, as well as how to indentify their gender. I took hair clippings and fecal samples, which yield data about the bats' diet. Their diet, in turn, gives us data about which pests they eat and therefore help control. I also learned about bats' echolocation: they have a special muscle over their ears that closes when they echolocate so that they don't burst their own eardrum. Also, some insects have evolved a special call that will disrupt bats echolocation so bats can't track it.

Sensory biology: echolocation from click to call, mouth to wing.

PubMed

Fenton, M Brock; Ratcliffe, John M

2014-12-15

Echolocators use echoes of sounds they produce, clicks or calls, to detect objects. Usually, these signals originate from the head. New work reveals that three species of bats use their wings to generate echolocation signals. Copyright © 2014 Elsevier Ltd. All rights reserved.

Biosonar performance of foraging Blainvilles beaked whales (Mesoplodon densirostris)

NASA Astrophysics Data System (ADS)

Madsen, Peter T.; Johnson, Mark; Tyack, Peter L.; Aguilar de Soto, Natacha; Zimmer, Walter M. X.

2004-05-01

Echolocating animals like bats and toothed whales navigate and locate food by means of echoes from sounds transmitted by the animals themselves. Toothed whale echolocation has been studied intensively in captivity, but little information exists on how echolocation is used by wild animals for orientation and prey location. To expand on this issue, a noninvasive, acoustic Dtag (96-kHz sampling, 16-bit resolution) was deployed on two Blainvilles beaked whales. The tagged whales only clicked at depths below 200 m during deep foraging dives. The echolocation clicks are directional, 250-ms transients with peak energy in the 30-40-kHz band. Echoes from the seafloor and from prey items were recorded. The regular click rate is not adjusted to the decreasing echo delay from incoming prey until the target is within an approximate body length of the whale after which the click rate is increased rapidly akin to the buzz phase of echolocating bats. This suggests that the whales use different sonar strategies for operating in near versus far field modes. Changes in received echo intensities from prey targets during approaches are compared to the active gain control in the receiving system of bats and in the transmitting system of dolphins.

Assessing bat detectability and occupancy with multiple automated echolocation detectors

USGS Publications Warehouse

Gorresen, P.M.; Miles, A.C.; Todd, C.M.; Bonaccorso, F.J.; Weller, T.J.

2008-01-01

Occupancy analysis and its ability to account for differential detection probabilities is important for studies in which detecting echolocation calls is used as a measure of bat occurrence and activity. We examined the feasibility of remotely acquiring bat encounter histories to estimate detection probability and occupancy. We used echolocation detectors coupled to digital recorders operating at a series of proximate sites on consecutive nights in 2 trial surveys for the Hawaiian hoary bat (Lasiurus cinereus semotus). Our results confirmed that the technique is readily amenable for use in occupancy analysis. We also conducted a simulation exercise to assess the effects of sampling effort on parameter estimation. The results indicated that the precision and bias of parameter estimation were often more influenced by the number of sites sampled than number of visits. Acceptable accuracy often was not attained until at least 15 sites or 15 visits were used to estimate detection probability and occupancy. The method has significant potential for use in monitoring trends in bat activity and in comparative studies of habitat use. ?? 2008 American Society of Mammalogists.

Bat mortality and activity at a Northern Iowa wind resource area

USGS Publications Warehouse

Jain, A.A.; Koford, Rolf R.; Hancock, A.W.; Zenner, G.G.

2011-01-01

We examined bat collision mortality, activity and species composition at an 89-turbine wind resource area in farmland of north-central Iowa from mid-Apr. to mid-Dec., 2003 and mid-Mar. to mid-Dec., 2004. We found 30 bats beneath turbines on cleared ground and gravel access areas in 2003 and 45 bats in 2004. After adjusting for search probability, search efficiency and scavenging rate, we estimated total bat mortality at 396 ?? 72 (95 ci) in 2003 and 636 ?? 112 (95 ci) in 2004. Although carcasses were mostly migratory tree bats, we found a considerable proportion of little brown bats (Myotis lucifugus). We recorded 1465 bat echolocation call files at turbine sites ( 34.88 call files/detector-night) and 1536 bat call files at adjacent non-turbine sites ( 36.57 call files/detector-night). Bat activity did not differ significantly between turbine and non-turbine sites. A large proportion of recorded call files were made by Myotis sp. but this may be because we detected activity at ground level only. There was no relationship between types of turbine lights and either collision mortality or echolocation activity. The highest levels of bat echolocation activity and collision mortality were recorded during Jul. and Aug. during the autumn dispersal and migration period. The fatality rates for bats in general and little brown bats in particular were higher at the Top of Iowa Wind Resource Area than at other, comparable studies in the region. Future efforts to study behavior of bats in flight around turbines as well as cumulative impact studies should not ignore non-tree dwelling bats, generally regarded as minimally affected. ?? 2011, American Midland Naturalist.

Sensing in a noisy world: lessons from auditory specialists, echolocating bats.

PubMed

Corcoran, Aaron J; Moss, Cynthia F

2017-12-15

All animals face the essential task of extracting biologically meaningful sensory information from the 'noisy' backdrop of their environments. Here, we examine mechanisms used by echolocating bats to localize objects, track small prey and communicate in complex and noisy acoustic environments. Bats actively control and coordinate both the emission and reception of sound stimuli through integrated sensory and motor mechanisms that have evolved together over tens of millions of years. We discuss how bats behave in different ecological scenarios, including detecting and discriminating target echoes from background objects, minimizing acoustic interference from competing conspecifics and overcoming insect noise. Bats tackle these problems by deploying a remarkable array of auditory behaviors, sometimes in combination with the use of other senses. Behavioral strategies such as ceasing sonar call production and active jamming of the signals of competitors provide further insight into the capabilities and limitations of echolocation. We relate these findings to the broader topic of how animals extract relevant sensory information in noisy environments. While bats have highly refined abilities for operating under noisy conditions, they face the same challenges encountered by many other species. We propose that the specialized sensory mechanisms identified in bats are likely to occur in analogous systems across the animal kingdom. © 2017. Published by The Company of Biologists Ltd.

Acoustic mirror effect increases prey detection distance in trawling bats

NASA Astrophysics Data System (ADS)

Siemers, Björn M.; Baur, Eric; Schnitzler, Hans-Ulrich

2005-06-01

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.

Acoustic mirror effect increases prey detection distance in trawling bats.

PubMed

Siemers, Björn M; Baur, Eric; Schnitzler, Hans-Ulrich

2005-06-01

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.

Directionality of nose-emitted echolocation calls from bats without a nose leaf (Plecotus auritus).

PubMed

Jakobsen, Lasse; Hallam, John; Moss, Cynthia F; Hedenström, Anders

2018-02-13

All echolocating bats and whales measured to date emit a directional bio-sonar beam that affords them a number of advantages over an omni-directional beam, i.e. reduced clutter, increased source level and inherent directional information. In this study, we investigated the importance of directional sound emission for navigation through echolocation by measuring the sonar beam of brown long-eared bats, Plecotus auritus Plecotus auritus emits sound through the nostrils but has no external appendages to readily facilitate a directional sound emission as found in most nose emitters. The study shows that P. auritus , despite lacking an external focusing apparatus, emits a directional echolocation beam (directivity index=13 dB) and that the beam is more directional vertically (-6 dB angle at 22 deg) than horizontally (-6 dB angle at 35 deg). Using a simple numerical model, we found that the recorded emission pattern is achievable if P. auritus emits sound through the nostrils as well as the mouth. The study thus supports the hypothesis that a directional echolocation beam is important for perception through echolocation and we propose that animals with similarly non-directional emitter characteristics may facilitate a directional sound emission by emitting sound through both the nostrils and the mouth. © 2018. Published by The Company of Biologists Ltd.

Regulation of bat echolocation pulse acoustics by striatal dopamine.

PubMed

Tressler, Jedediah; Schwartz, Christine; Wellman, Paul; Hughes, Samuel; Smotherman, Michael

2011-10-01

The ability to control the bandwidth, amplitude and duration of echolocation pulses is a crucial aspect of echolocation performance but few details are known about the neural mechanisms underlying the control of these voice parameters in any mammal. The basal ganglia (BG) are a suite of forebrain nuclei centrally involved in sensory-motor control and are characterized by their dependence on dopamine. We hypothesized that pharmacological manipulation of brain dopamine levels could reveal how BG circuits might influence the acoustic structure of bat echolocation pulses. A single intraperitoneal injection of a low dose (5 mg kg(-1)) of the neurotoxin 1-methyl-4-phenylpyridine (MPTP), which selectively targets dopamine-producing cells of the substantia nigra, produced a rapid degradation in pulse acoustic structure and eliminated the bat's ability to make compensatory changes in pulse amplitude in response to background noise, i.e. the Lombard response. However, high-performance liquid chromatography (HPLC) measurements of striatal dopamine concentrations revealed that the main effect of MPTP was a fourfold increase rather than the predicted decrease in striatal dopamine levels. After first using autoradiographic methods to confirm the presence and location of D(1)- and D(2)-type dopamine receptors in the bat striatum, systemic injections of receptor subtype-specific agonists showed that MPTP's effects on pulse acoustics were mimicked by a D(2)-type dopamine receptor agonist (Quinpirole) but not by a D(1)-type dopamine receptor agonist (SKF82958). The results suggest that BG circuits have the capacity to influence echolocation pulse acoustics, particularly via D(2)-type dopamine receptor-mediated pathways, and may therefore represent an important mechanism for vocal control in bats.

Regulation of bat echolocation pulse acoustics by striatal dopamine

PubMed Central

Tressler, Jedediah; Schwartz, Christine; Wellman, Paul; Hughes, Samuel; Smotherman, Michael

2011-01-01

SUMMARY The ability to control the bandwidth, amplitude and duration of echolocation pulses is a crucial aspect of echolocation performance but few details are known about the neural mechanisms underlying the control of these voice parameters in any mammal. The basal ganglia (BG) are a suite of forebrain nuclei centrally involved in sensory-motor control and are characterized by their dependence on dopamine. We hypothesized that pharmacological manipulation of brain dopamine levels could reveal how BG circuits might influence the acoustic structure of bat echolocation pulses. A single intraperitoneal injection of a low dose (5 mg kg–1) of the neurotoxin 1-methyl-4-phenylpyridine (MPTP), which selectively targets dopamine-producing cells of the substantia nigra, produced a rapid degradation in pulse acoustic structure and eliminated the bat's ability to make compensatory changes in pulse amplitude in response to background noise, i.e. the Lombard response. However, high-performance liquid chromatography (HPLC) measurements of striatal dopamine concentrations revealed that the main effect of MPTP was a fourfold increase rather than the predicted decrease in striatal dopamine levels. After first using autoradiographic methods to confirm the presence and location of D1- and D2-type dopamine receptors in the bat striatum, systemic injections of receptor subtype-specific agonists showed that MPTP's effects on pulse acoustics were mimicked by a D2-type dopamine receptor agonist (Quinpirole) but not by a D1-type dopamine receptor agonist (SKF82958). The results suggest that BG circuits have the capacity to influence echolocation pulse acoustics, particularly via D2-type dopamine receptor-mediated pathways, and may therefore represent an important mechanism for vocal control in bats. PMID:21900471

[Dietary composition, echolocation pulses and morphological measurements of the long-fingered bat Miniopterus fuliginosus (Chiroptera: Vespertilioninae)].

PubMed

Hu, Kai-Liang; Wei, Li; Zhu, Teng-Teng; Wang, Xu-Zhong; Zhang, Li-Biao

2011-04-01

We investigated food (insect) availability in foraging areas utilized by the long-fingered bat Miniopterus fuliginosus using light traps, fish netting and fecal analysis. The dominant preys of M. fuliginosus were Lepidoptera (55%, by volume percent) and Coleoptera (38%) of a relatively large body size. M. fuliginosus has relatively long, narrow wings and a wing span of 6.58+/-0.12 and high wing loading of 9.85+/-0.83 N/m2. The echolocation calls of free flying M. fuliginosus were FM signals, with a pulse duration of 1.45+/-0.06 ms, interpulse interval of 63.08+/-21.55 ms, and low dominant frequency of 44.50+/-2.26 kHz. This study shows that the morphological characteristics and echolocation calls of long-fingered bats are closely linked to their predatory behavior.

The influence of feeding on the evolution of sensory signals: a comparative test of an evolutionary trade-off between masticatory and sensory functions of skulls in southern African horseshoe bats (Rhinolophidae).

PubMed

Jacobs, D S; Bastian, A; Bam, L

2014-12-01

The skulls of animals have to perform many functions. Optimization for one function may mean another function is less optimized, resulting in evolutionary trade-offs. Here, we investigate whether a trade-off exists between the masticatory and sensory functions of animal skulls using echolocating bats as model species. Several species of rhinolophid bats deviate from the allometric relationship between body size and echolocation frequency. Such deviation may be the result of selection for increased bite force, resulting in a decrease in snout length which could in turn lead to higher echolocation frequencies. If so, there should be a positive relationship between bite force and echolocation frequency. We investigated this relationship in several species of southern African rhinolophids using phylogenetically informed analyses of the allometry of their bite force and echolocation frequency and of the three-dimensional shape of their skulls. As predicted, echolocation frequency was positively correlated with bite force, suggesting that its evolution is influenced by a trade-off between the masticatory and sensory functions of the skull. In support of this, variation in skull shape was explained by both echolocation frequency (80%) and bite force (20%). Furthermore, it appears that selection has acted on the nasal capsules, which have a frequency-specific impedance matching function during vocalization. There was a negative correlation between echolocation frequency and capsule volume across species. Optimization of the masticatory function of the skull may have been achieved through changes in the shape of the mandible and associated musculature, elements not considered in this study. © 2014 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2014 European Society For Evolutionary Biology.

Bat Facts and Fun.

ERIC Educational Resources Information Center

McKee, Judith A.

1992-01-01

Describes a unit of study for elementary school science on bats. Students investigate the different types of bats; examine their behavior; find facts that other students are unlikely to know; write stories about bats; and examine the concept of echolocation, the means by which bats navigate. Suggests integrated activities for mathematics…

Bats aggregate to improve prey search but might be impaired when their density becomes too high.

PubMed

Cvikel, Noam; Egert Berg, Katya; Levin, Eran; Hurme, Edward; Borissov, Ivailo; Boonman, Arjan; Amichai, Eran; Yovel, Yossi

2015-01-19

Social foraging is a very common yet extremely complex behavior. Numerous studies attempted to model it with little supporting evidence. Studying it in the wild is difficult because it requires monitoring the animal's movement, its foraging success, and its interactions with conspecifics. We present a novel system that enables full night ultrasonic recording of freely foraging bats, in addition to GPS tracking. As they rely on echolocation, audio recordings of bats allow tapping into their sensory acquisition of the world. Rapid changes in echolocation allowed us to reveal the bats' dynamic reactions in response to prey or conspecifics—two key behaviors that are extremely difficult to assess in most animals. We found that bats actively aggregate and forage as a group. However, we also found that when the group became too dense, bats were forced to devote sensory attention to conspecifics that frequently entered their biosonar "field of view," impairing the bats' prey detection performance. Why then did bats fly in such high densities? By emitting echolocation calls, bats constantly provide public information about their detection of prey. Bats could therefore benefit from intentionally flying at a distance that enables eavesdropping on conspecifics. Group foraging, therefore, probably allowed bats to effectively operate as an array of sensors, increasing their searching efficiency. We suggest that two opposing forces are at play in determining the efficient foraging density: on the one hand, higher densities improve prey detection, but on the other hand, they increase conspecific interference. Copyright © 2015 Elsevier Ltd. All rights reserved.

Pliocene bats (Chiroptera) from Kanapoi, Turkana Basin, Kenya.

PubMed

Gunnell, Gregg F; Manthi, Fredrick K

2018-04-05

Fossil bats from the Pliocene of Africa are extremely rare, especially in East Africa where meager records have been reported only from two localities in the Omo River Basin Shungura Formation and from a scattering of localities in the Afar Depression, both in Ethiopia. Here we report on a diverse assemblage of bats from Kanapoi in the Turkana Basin that date to approximately 4.19 million years ago. The Kanapoi bat community consists of four different species of fruit bats including a new genus and two new species as well as five species of echolocating bats, the most common of which are two new species of the molossid genus Mops. Additionally, among the echolocating bats, a new species of the emballonurid Saccolaimus is documented at Kanapoi along with an additional Saccolaimus species and a potentially new species of the nycterid Nycteris. Compared to other East African Pliocene bat assemblages, the Kanapoi bat community is unique in preserving molossids and curiously lacks any evidence of cave dwelling bats like rhinolophids or hipposiderids, which are both common at other East African sites. The bats making up the Kanapoi community all typically roost in trees, with some preferring deeper forests and larger trees (molossids), while the others (pteropodids, nycterids and emballonurids) roost in trees near open areas. Living fruit bats that are related to Kanapoi species typically forage for fruits along the margins of forests and in open savannah. The echolocating forms from Kanapoi consist of groups that aerially hawk for insects in open areas between patches of forest and along water courses. The habitats preferred by living relatives of the Kanapoi bats are in agreement with those constructed for Kanapoi based on other lines of evidence. Copyright © 2018. Published by Elsevier Ltd.

Adaptive evolution of the myo6 gene in old world fruit bats (family: pteropodidae).

PubMed

Shen, Bin; Han, Xiuqun; Jones, Gareth; Rossiter, Stephen J; Zhang, Shuyi

2013-01-01

Myosin VI (encoded by the Myo6 gene) is highly expressed in the inner and outer hair cells of the ear, retina, and polarized epithelial cells such as kidney proximal tubule cells and intestinal enterocytes. The Myo6 gene is thought to be involved in a wide range of physiological functions such as hearing, vision, and clathrin-mediated endocytosis. Bats (Chiroptera) represent one of the most fascinating mammal groups for molecular evolutionary studies of the Myo6 gene. A diversity of specialized adaptations occur among different bat lineages, such as echolocation and associated high-frequency hearing in laryngeal echolocating bats, large eyes and a strong dependence on vision in Old World fruit bats (Pteropodidae), and specialized high-carbohydrate but low-nitrogen diets in both Old World and New World fruit bats (Phyllostomidae). To investigate what role(s) the Myo6 gene might fulfill in bats, we sequenced the coding region of the Myo6 gene in 15 bat species and used molecular evolutionary analyses to detect evidence of positive selection in different bat lineages. We also conducted real-time PCR assays to explore the expression levels of Myo6 in a range of tissues from three representative bat species. Molecular evolutionary analyses revealed that the Myo6 gene, which was widely considered as a hearing gene, has undergone adaptive evolution in the Old World fruit bats which lack laryngeal echolocation and associated high-frequency hearing. Real-time PCR showed the highest expression level of the Myo6 gene in the kidney among ten tissues examined in three bat species, indicating an important role for this gene in kidney function. We suggest that Myo6 has undergone adaptive evolution in Old World fruit bats in relation to receptor-mediated endocytosis for the preservation of protein and essential nutrients.

Processing of Natural Echolocation Sequences in the Inferior Colliculus of Seba’s Fruit Eating Bat, Carollia perspicillata

PubMed Central

Kordes, Sebastian; Kössl, Manfred

2017-01-01

Abstract For the purpose of orientation, echolocating bats emit highly repetitive and spatially directed sonar calls. Echoes arising from call reflections are used to create an acoustic image of the environment. The inferior colliculus (IC) represents an important auditory stage for initial processing of echolocation signals. The present study addresses the following questions: (1) how does the temporal context of an echolocation sequence mimicking an approach flight of an animal affect neuronal processing of distance information to echo delays? (2) how does the IC process complex echolocation sequences containing echo information from multiple objects (multiobject sequence)? Here, we conducted neurophysiological recordings from the IC of ketamine-anaesthetized bats of the species Carollia perspicillata and compared the results from the IC with the ones from the auditory cortex (AC). Neuronal responses to an echolocation sequence was suppressed when compared to the responses to temporally isolated and randomized segments of the sequence. The neuronal suppression was weaker in the IC than in the AC. In contrast to the cortex, the time course of the acoustic events is reflected by IC activity. In the IC, suppression sharpens the neuronal tuning to specific call-echo elements and increases the signal-to-noise ratio in the units’ responses. When presenting multiple-object sequences, despite collicular suppression, the neurons responded to each object-specific echo. The latter allows parallel processing of multiple echolocation streams at the IC level. Altogether, our data suggests that temporally-precise neuronal responses in the IC could allow fast and parallel processing of multiple acoustic streams. PMID:29242823

Processing of Natural Echolocation Sequences in the Inferior Colliculus of Seba's Fruit Eating Bat, Carollia perspicillata.

PubMed

Beetz, M Jerome; Kordes, Sebastian; García-Rosales, Francisco; Kössl, Manfred; Hechavarría, Julio C

2017-01-01

For the purpose of orientation, echolocating bats emit highly repetitive and spatially directed sonar calls. Echoes arising from call reflections are used to create an acoustic image of the environment. The inferior colliculus (IC) represents an important auditory stage for initial processing of echolocation signals. The present study addresses the following questions: (1) how does the temporal context of an echolocation sequence mimicking an approach flight of an animal affect neuronal processing of distance information to echo delays? (2) how does the IC process complex echolocation sequences containing echo information from multiple objects (multiobject sequence)? Here, we conducted neurophysiological recordings from the IC of ketamine-anaesthetized bats of the species Carollia perspicillata and compared the results from the IC with the ones from the auditory cortex (AC). Neuronal responses to an echolocation sequence was suppressed when compared to the responses to temporally isolated and randomized segments of the sequence. The neuronal suppression was weaker in the IC than in the AC. In contrast to the cortex, the time course of the acoustic events is reflected by IC activity. In the IC, suppression sharpens the neuronal tuning to specific call-echo elements and increases the signal-to-noise ratio in the units' responses. When presenting multiple-object sequences, despite collicular suppression, the neurons responded to each object-specific echo. The latter allows parallel processing of multiple echolocation streams at the IC level. Altogether, our data suggests that temporally-precise neuronal responses in the IC could allow fast and parallel processing of multiple acoustic streams.

Guide to the BATS Resource Trunk.

ERIC Educational Resources Information Center

Arizona Game and Fish Dept., Phoenix.

This guide provides detailed information, resources, and activities to teach students about the bats of Arizona. Chapters include: (1) "What is a Bat?"; (2) "Megabat or Microbat?"; (3) "Bat Anatomy"; (4) Diet and Feeding"; (5) Echolocation"; (6) Reproduction and Lifespan"; (7) "Flight"; (8)…

Coordinated Control of Acoustical Field of View and Flight in Three-Dimensional Space for Consecutive Capture by Echolocating Bats during Natural Foraging.

PubMed

Sumiya, Miwa; Fujioka, Emyo; Motoi, Kazuya; Kondo, Masaru; Hiryu, Shizuko

2017-01-01

Echolocating bats prey upon small moving insects in the dark using sophisticated sonar techniques. The direction and directivity pattern of the ultrasound broadcast of these bats are important factors that affect their acoustical field of view, allowing us to investigate how the bats control their acoustic attention (pulse direction) for advanced flight maneuvers. The purpose of this study was to understand the behavioral strategies of acoustical sensing of wild Japanese house bats Pipistrellus abramus in three-dimensional (3D) space during consecutive capture flights. The results showed that when the bats successively captured multiple airborne insects in short time intervals (less than 1.5 s), they maintained not only the immediate prey but also the subsequent one simultaneously within the beam widths of the emitted pulses in both horizontal and vertical planes before capturing the immediate one. This suggests that echolocating bats maintain multiple prey within their acoustical field of view by a single sensing using a wide directional beam while approaching the immediate prey, instead of frequently shifting acoustic attention between multiple prey. We also numerically simulated the bats' flight trajectories when approaching two prey successively to investigate the relationship between the acoustical field of view and the prey direction for effective consecutive captures. This simulation demonstrated that acoustically viewing both the immediate and the subsequent prey simultaneously increases the success rate of capturing both prey, which is considered to be one of the basic axes of efficient route planning for consecutive capture flight. The bat's wide sonar beam can incidentally cover multiple prey while the bat forages in an area where the prey density is high. Our findings suggest that the bats then keep future targets within their acoustical field of view for effective foraging. In addition, in both the experimental results and the numerical simulations, the acoustic sensing and flights of the bats showed narrower vertical ranges than horizontal ranges. This suggests that the bats control their acoustic sensing according to different schemes in the horizontal and vertical planes according to their surroundings. These findings suggest that echolocating bats coordinate their control of the acoustical field of view and flight for consecutive captures in 3D space during natural foraging.

Active listening for spatial orientation in a complex auditory scene.

PubMed

Moss, Cynthia F; Bohn, Kari; Gilkenson, Hannah; Surlykke, Annemarie

2006-04-01

To successfully negotiate a complex environment, an animal must control the timing of motor behaviors in coordination with dynamic sensory information. Here, we report on adaptive temporal control of vocal-motor behavior in an echolocating bat, Eptesicus fuscus, as it captured tethered insects close to background vegetation. Recordings of the bat's sonar vocalizations were synchronized with high-speed video images that were used to reconstruct the bat's three-dimensional flight path and the positions of target and vegetation. When the bat encountered the difficult task of taking insects as close as 10-20 cm from the vegetation, its behavior changed significantly from that under open room conditions. Its success rate decreased by about 50%, its time to initiate interception increased by a factor of ten, and its high repetition rate "terminal buzz" decreased in duration by a factor of three. Under all conditions, the bat produced prominent sonar "strobe groups," clusters of echolocation pulses with stable intervals. In the final stages of insect capture, the bat produced strobe groups at a higher incidence when the insect was positioned near clutter. Strobe groups occurred at all phases of the wingbeat (and inferred respiration) cycle, challenging the hypothesis of strict synchronization between respiration and sound production in echolocating bats. The results of this study provide a clear demonstration of temporal vocal-motor control that directly impacts the signals used for perception.

Active Listening for Spatial Orientation in a Complex Auditory Scene

PubMed Central

Bohn, Kari; Gilkenson, Hannah; Surlykke, Annemarie

2006-01-01

To successfully negotiate a complex environment, an animal must control the timing of motor behaviors in coordination with dynamic sensory information. Here, we report on adaptive temporal control of vocal–motor behavior in an echolocating bat, Eptesicus fuscus, as it captured tethered insects close to background vegetation. Recordings of the bat's sonar vocalizations were synchronized with high-speed video images that were used to reconstruct the bat's three-dimensional flight path and the positions of target and vegetation. When the bat encountered the difficult task of taking insects as close as 10–20 cm from the vegetation, its behavior changed significantly from that under open room conditions. Its success rate decreased by about 50%, its time to initiate interception increased by a factor of ten, and its high repetition rate “terminal buzz” decreased in duration by a factor of three. Under all conditions, the bat produced prominent sonar “strobe groups,” clusters of echolocation pulses with stable intervals. In the final stages of insect capture, the bat produced strobe groups at a higher incidence when the insect was positioned near clutter. Strobe groups occurred at all phases of the wingbeat (and inferred respiration) cycle, challenging the hypothesis of strict synchronization between respiration and sound production in echolocating bats. The results of this study provide a clear demonstration of temporal vocal–motor control that directly impacts the signals used for perception. PMID:16509770

Bats adjust their mouth gape to zoom their biosonar field of view.

PubMed

Kounitsky, Pavel; Rydell, Jens; Amichai, Eran; Boonman, Arjan; Eitan, Ofri; Weiss, Anthony J; Yovel, Yossi

2015-05-26

Active sensing, where sensory acquisition is actively modulated, is an inherent component of almost all sensory systems. Echolocating bats are a prime example of active sensing. They can rapidly adjust many of their biosonar parameters to optimize sensory acquisition. They dynamically adjust pulse design, pulse duration, and pulse rate within dozens of milliseconds according to the sensory information that is required for the task that they are performing. The least studied and least understood degree of freedom in echolocation is emission beamforming--the ability to change the shape of the sonar sound beam in a functional way. Such an ability could have a great impact on the bat's control over its sensory perception. On the one hand, the bat could direct more energy into a narrow sector to zoom its biosonar field of view, and on the other hand, it could widen the beam to increase the space that it senses. We show that freely behaving bats constantly control their biosonar field of view in natural situations by rapidly adjusting their emitter aperture--the mouth gape. The bats dramatically narrowed the beam when entering a confined space, and they dramatically widened it within dozens of milliseconds when flying toward open space. Hence, mouth-emitting bats dynamically adjust their mouth gape to optimize the area that they sense with their echolocation system.

A neural mechanism for detecting the distance of a selected target by modulating the FM sweep rate of biosonar in echolocation of bat.

PubMed

Kamata, Eigo; Inoue, Satoru; Zheng, MeiHong; Kashimori, Yoshiki; Kambara, Takeshi

2004-01-01

Most species of bats making echolocation use frequency modulated (FM) ultrasonic pulses to measure the distance to targets. These bats detect with a high accuracy the arrival time differences between emitted pulses and their echoes generated by targets. In order to clarify the neural mechanism for echolocation, we present neural model of inferior colliculus (IC), medial geniculate body (MGB) and auditory cortex (AC) along which information of echo delay times is processed. The bats increase the downward frequency sweep rate of emitted FM pulse as they approach the target. The functional role of this modulation of sweep rate is not yet clear. In order to investigate the role, we calculated the response properties of our models of IC, MGB, and AC changing the target distance and the sweep rate. We found based on the simulations that the distance of a target in various ranges may be encoded the most clearly into the activity pattern of delay time map network in AC, when the sweep rate of FM pulse used is coincided with the observed value which the bats adopt for each range of target distance.

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

NASA Astrophysics Data System (ADS)

Boonman, Arjan M.; Parsons, Stuart; Jones, Gareth

2003-01-01

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.

Congruent representation of visual and acoustic space in the superior colliculus of the echolocating bat Phyllostomus discolor.

PubMed

Hoffmann, Susanne; Vega-Zuniga, Tomas; Greiter, Wolfgang; Krabichler, Quirin; Bley, Alexandra; Matthes, Mariana; Zimmer, Christiane; Firzlaff, Uwe; Luksch, Harald

2016-11-01

The midbrain superior colliculus (SC) commonly features a retinotopic representation of visual space in its superficial layers, which is congruent with maps formed by multisensory neurons and motor neurons in its deep layers. Information flow between layers is suggested to enable the SC to mediate goal-directed orienting movements. While most mammals strongly rely on vision for orienting, some species such as echolocating bats have developed alternative strategies, which raises the question how sensory maps are organized in these animals. We probed the visual system of the echolocating bat Phyllostomus discolor and found that binocular high acuity vision is frontally oriented and thus aligned with the biosonar system, whereas monocular visual fields cover a large area of peripheral space. For the first time in echolocating bats, we could show that in contrast with other mammals, visual processing is restricted to the superficial layers of the SC. The topographic representation of visual space, however, followed the general mammalian pattern. In addition, we found a clear topographic representation of sound azimuth in the deeper collicular layers, which was congruent with the superficial visual space map and with a previously documented map of orienting movements. Especially for bats navigating at high speed in densely structured environments, it is vitally important to transfer and coordinate spatial information between sensors and motor systems. Here, we demonstrate first evidence for the existence of congruent maps of sensory space in the bat SC that might serve to generate a unified representation of the environment to guide motor actions. © 2016 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Doppler-shift compensation in the Taiwanese leaf-nosed bat (Hipposideros terasensis) recorded with a telemetry microphone system during flight

NASA Astrophysics Data System (ADS)

Hiryu, Shizuko; Katsura, Koji; Lin, Liang-Kong; Riquimaroux, Hiroshi; Watanabe, Yoshiaki

2005-12-01

Biosonar behavior was examined in Taiwanese leaf-nosed bats (Hipposideros terasensis; CF-FM bats) during flight. Echolocation sounds were recorded using a telemetry microphone mounted on the bat's head. Flight speed and three-dimensional trajectory of the bat were reconstructed from images taken with a dual high-speed video camera system. Bats were observed to change the intensity and emission rate of pulses depending on the distance from the landing site. Frequencies of the dominant second harmonic constant frequency component (CF2) of calls estimated from the bats' flight speed agreed strongly with observed values. Taiwanese leaf-nosed bats changed CF2 frequencies depending on flight speed, which caused the CF2 frequencies of the Doppler-shifted echoes to remain constant. Pulse frequencies were also estimated using echoes returning directly ahead of the bat and from its sides for two different flight conditions: landing and U-turn. Bats in flight may periodically alter their attended angles from the front to the side when emitting echolocation pulses.

Echolocation calls and communication calls are controlled differentially in the brainstem of the bat Phyllostomus discolor

PubMed Central

Fenzl, Thomas; Schuller, Gerd

2005-01-01

Background Echolocating bats emit vocalizations that can be classified either as echolocation calls or communication calls. Neural control of both types of calls must govern the same pool of motoneurons responsible for vocalizations. Electrical microstimulation in the periaqueductal gray matter (PAG) elicits both communication and echolocation calls, whereas stimulation of the paralemniscal area (PLA) induces only echolocation calls. In both the PAG and the PLA, the current thresholds for triggering natural vocalizations do not habituate to stimuli and remain low even for long stimulation periods, indicating that these structures have relative direct access to the final common pathway for vocalization. This study intended to clarify whether echolocation calls and communication calls are controlled differentially below the level of the PAG via separate vocal pathways before converging on the motoneurons used in vocalization. Results Both structures were probed simultaneously in a single experimental approach. Two stimulation electrodes were chronically implanted within the PAG in order to elicit either echolocation or communication calls. Blockade of the ipsilateral PLA site with iontophoretically application of the glutamate antagonist kynurenic acid did not impede either echolocation or communication calls elicited from the PAG. However, blockade of the contralateral PLA suppresses PAG-elicited echolocation calls but not communication calls. In both cases the blockade was reversible. Conclusion The neural control of echolocation and communication calls seems to be differentially organized below the level of the PAG. The PLA is an essential functional unit for echolocation call control before the descending pathways share again the final common pathway for vocalization. PMID:16053533

Ambient noise causes independent changes in distinct spectro-temporal features of echolocation calls in horseshoe bats.

PubMed

Hage, Steffen R; Jiang, Tinglei; Berquist, Sean W; Feng, Jiang; Metzner, Walter

2014-07-15

One of the most efficient mechanisms to optimize signal-to-noise ratios is the Lombard effect - an involuntary rise in call amplitude due to ambient noise. It is often accompanied by changes in the spectro-temporal composition of calls. We examined the effects of broadband-filtered noise on the spectro-temporal composition of horseshoe bat echolocation calls, which consist of a constant-frequency component and initial and terminal frequency-modulated components. We found that the frequency-modulated components became larger for almost all noise conditions, whereas the bandwidth of the constant-frequency component increased only when broadband-filtered noise was centered on or above the calls' dominant or fundamental frequency. This indicates that ambient noise independently modifies the associated acoustic parameters of the Lombard effect, such as spectro-temporal features, and could significantly affect the bat's ability to detect and locate targets. Our findings may be of significance in evaluating the impact of environmental noise on echolocation behavior in bats. © 2014. Published by The Company of Biologists Ltd.

Divergence of dim-light vision among bats (order: Chiroptera) as estimated by molecular and electrophysiological methods.

PubMed

Liu, He-Qun; Wei, Jing-Kuan; Li, Bo; Wang, Ming-Shan; Wu, Rui-Qi; Rizak, Joshua D; Zhong, Li; Wang, Lu; Xu, Fu-Qiang; Shen, Yong-Yi; Hu, Xin-Tian; Zhang, Ya-Ping

2015-06-23

Dim-light vision is present in all bats, but is divergent among species. Old-World fruit bats (Pteropodidae) have fully developed eyes; the eyes of insectivorous bats are generally degraded, and these bats rely on well-developed echolocation. An exception is the Emballonuridae, which are capable of laryngeal echolocation but prefer to use vision for navigation and have normal eyes. In this study, integrated methods, comprising manganese-enhanced magnetic resonance imaging (MEMRI), f-VEP and RNA-seq, were utilized to verify the divergence. The results of MEMRI showed that Pteropodidae bats have a much larger superior colliculus (SC)/ inferior colliculus (IC) volume ratio (3:1) than insectivorous bats (1:7). Furthermore, the absolute visual thresholds (log cd/m(2)•s) of Pteropodidae (-6.30 and -6.37) and Emballonuridae (-3.71) bats were lower than those of other insectivorous bats (-1.90). Finally, genes related to the visual pathway showed signs of positive selection, convergent evolution, upregulation and similar gene expression patterns in Pteropodidae and Emballonuridae bats. Different results imply that Pteropodidae and Emballonuridae bats have more developed vision than the insectivorous bats and suggest that further research on bat behavior is warranted.

Extremely high frequency sensitivity in a ‘simple’ ear

PubMed Central

Moir, Hannah M.; Jackson, Joseph C.; Windmill, James F. C.

2013-01-01

An evolutionary war is being played out between the bat, which uses ultrasonic calls to locate insect prey, and the moth, which uses microscale ears to listen for the approaching bat. While the highest known frequency of bat echolocation calls is 212 kHz, the upper limit of moth hearing is considered much lower. Here, we show that the greater wax moth, Galleria mellonella, is capable of hearing ultrasonic frequencies approaching 300 kHz; the highest frequency sensitivity of any animal. With auditory frequency sensitivity that is unprecedented in the animal kingdom, the greater wax moth is ready and armed for any echolocation call adaptations made by the bat in the on-going bat–moth evolutionary war. PMID:23658005

Bat noseleaf model: echolocation function, design considerations, and experimental verification.

PubMed

Kuc, Roman

2011-05-01

This paper describes a possible bat noseleaf echolocation function that improves target elevation resolution. Bats with a protruding noseleaf can rotate the lancet to act as an acoustic mirror that reflects the nostril emission, modeled as a virtual nostril that produces a delayed emission. The cancellation of the nostril and virtual nostril components at a target produces a sharp spectral notch whose frequency location relates to target elevation. This notch can be observed directly from the swept-frequency emission waveform, suggesting cochlear processing capabilities. Physical acoustic principles indicate the design considerations and trade-offs that a bat can accomplish through noseleaf shape and emission characteristics. An experimental model verifies the analysis and exhibits an elevation versus notch frequency sensitivity of approximately 1°/kHz.

Coordinated Control of Acoustical Field of View and Flight in Three-Dimensional Space for Consecutive Capture by Echolocating Bats during Natural Foraging

PubMed Central

Sumiya, Miwa; Fujioka, Emyo; Motoi, Kazuya; Kondo, Masaru; Hiryu, Shizuko

2017-01-01

Echolocating bats prey upon small moving insects in the dark using sophisticated sonar techniques. The direction and directivity pattern of the ultrasound broadcast of these bats are important factors that affect their acoustical field of view, allowing us to investigate how the bats control their acoustic attention (pulse direction) for advanced flight maneuvers. The purpose of this study was to understand the behavioral strategies of acoustical sensing of wild Japanese house bats Pipistrellus abramus in three-dimensional (3D) space during consecutive capture flights. The results showed that when the bats successively captured multiple airborne insects in short time intervals (less than 1.5 s), they maintained not only the immediate prey but also the subsequent one simultaneously within the beam widths of the emitted pulses in both horizontal and vertical planes before capturing the immediate one. This suggests that echolocating bats maintain multiple prey within their acoustical field of view by a single sensing using a wide directional beam while approaching the immediate prey, instead of frequently shifting acoustic attention between multiple prey. We also numerically simulated the bats’ flight trajectories when approaching two prey successively to investigate the relationship between the acoustical field of view and the prey direction for effective consecutive captures. This simulation demonstrated that acoustically viewing both the immediate and the subsequent prey simultaneously increases the success rate of capturing both prey, which is considered to be one of the basic axes of efficient route planning for consecutive capture flight. The bat’s wide sonar beam can incidentally cover multiple prey while the bat forages in an area where the prey density is high. Our findings suggest that the bats then keep future targets within their acoustical field of view for effective foraging. In addition, in both the experimental results and the numerical simulations, the acoustic sensing and flights of the bats showed narrower vertical ranges than horizontal ranges. This suggests that the bats control their acoustic sensing according to different schemes in the horizontal and vertical planes according to their surroundings. These findings suggest that echolocating bats coordinate their control of the acoustical field of view and flight for consecutive captures in 3D space during natural foraging. PMID:28085936

Robustness of cortical and subcortical processing in the presence of natural masking sounds.

PubMed

Beetz, M Jerome; García-Rosales, Francisco; Kössl, Manfred; Hechavarría, Julio C

2018-05-01

Processing of ethologically relevant stimuli could be interfered by non-relevant stimuli. Animals have behavioral adaptations to reduce signal interference. It is largely unexplored whether the behavioral adaptations facilitate neuronal processing of relevant stimuli. Here, we characterize behavioral adaptations in the presence of biotic noise in the echolocating bat Carollia perspicillata and we show that the behavioral adaptations could facilitate neuronal processing of biosonar information. According to the echolocation behavior, bats need to extract their own signals in the presence of vocalizations from conspecifics. With playback experiments, we demonstrate that C. perspicillata increases the sensory acquisition rate by emitting groups of echolocation calls when flying in noisy environments. Our neurophysiological results from the auditory midbrain and cortex show that the high sensory acquisition rate does not vastly increase neuronal suppression and that the response to an echolocation sequence is partially preserved in the presence of biosonar signals from conspecifics.

A blind climber: The first evidence of ultrasonic echolocation in arboreal mammals.

PubMed

Panyutina, Aleksandra A; Kuznetsov, Alexander N; Volodin, Ilya A; Abramov, Alexei V; Soldatova, Irina B

2017-03-01

The means of orientation is studied in the Vietnamese pygmy dormouse Typhlomys chapensis, a poorly known enigmatic semi-fossorial semi-arboreal rodent. Data on eye structure are presented, which prove that Typhlomys (translated as "the blind mouse") is incapable of object vision: the retina is folded and retains no more than 2500 ganglion cells in the focal plane, and the optic nerve is subject to gliosis. Hence, Typhlomys has no other means for rapid long-range orientation among tree branches other than echolocation. Ultrasonic vocalization recordings at the frequency range of 50-100 kHz support this hypothesis. The vocalizations are represented by bouts of up to 7 more or less evenly-spaced and uniform frequency-modulated sweep-like pulses in rapid succession. Structurally, these sweeps are similar to frequency-modulated ultrasonic echolocation calls of some bat species, but they are too faint to be revealed with a common bat detector. When recording video simultaneously with the ultrasonic audio, a significantly greater pulse rate during locomotion compared to that of resting animals has been demonstrated. Our findings of locomotion-associated ultrasonic vocalization in a fast-climbing but weakly-sighted small mammal ecotype add support to the "echolocation-first theory" of pre-flight origin of echolocation in bats. © 2016 International Society of Zoological Sciences, Institute of Zoology/Chinese Academy of Sciences and John Wiley & Sons Australia, Ltd.

Action Enhances Acoustic Cues for 3-D Target Localization by Echolocating Bats

PubMed Central

Wohlgemuth, Melville J.

2016-01-01

Under natural conditions, animals encounter a barrage of sensory information from which they must select and interpret biologically relevant signals. Active sensing can facilitate this process by engaging motor systems in the sampling of sensory information. The echolocating bat serves as an excellent model to investigate the coupling between action and sensing because it adaptively controls both the acoustic signals used to probe the environment and movements to receive echoes at the auditory periphery. We report here that the echolocating bat controls the features of its sonar vocalizations in tandem with the positioning of the outer ears to maximize acoustic cues for target detection and localization. The bat’s adaptive control of sonar vocalizations and ear positioning occurs on a millisecond timescale to capture spatial information from arriving echoes, as well as on a longer timescale to track target movement. Our results demonstrate that purposeful control over sonar sound production and reception can serve to improve acoustic cues for localization tasks. This finding also highlights the general importance of movement to sensory processing across animal species. Finally, our discoveries point to important parallels between spatial perception by echolocation and vision. PMID:27608186

Cortical neurons of bats respond best to echoes from nearest targets when listening to natural biosonar multi-echo streams.

PubMed

Beetz, M Jerome; Hechavarría, Julio C; Kössl, Manfred

2016-10-27

Bats orientate in darkness by listening to echoes from their biosonar calls, a behaviour known as echolocation. Recent studies showed that cortical neurons respond in a highly selective manner when stimulated with natural echolocation sequences that contain echoes from single targets. However, it remains unknown how cortical neurons process echolocation sequences containing echo information from multiple objects. In the present study, we used echolocation sequences containing echoes from three, two or one object separated in the space depth as stimuli to study neuronal activity in the bat auditory cortex. Neuronal activity was recorded with multi-electrode arrays placed in the dorsal auditory cortex, where neurons tuned to target-distance are found. Our results show that target-distance encoding neurons are mostly selective to echoes coming from the closest object, and that the representation of echo information from distant objects is selectively suppressed. This suppression extends over a large part of the dorsal auditory cortex and may override possible parallel processing of multiple objects. The presented data suggest that global cortical suppression might establish a cortical "default mode" that allows selectively focusing on close obstacle even without active attention from the animals.

Cortical neurons of bats respond best to echoes from nearest targets when listening to natural biosonar multi-echo streams

PubMed Central

Beetz, M. Jerome; Hechavarría, Julio C.; Kössl, Manfred

2016-01-01

Bats orientate in darkness by listening to echoes from their biosonar calls, a behaviour known as echolocation. Recent studies showed that cortical neurons respond in a highly selective manner when stimulated with natural echolocation sequences that contain echoes from single targets. However, it remains unknown how cortical neurons process echolocation sequences containing echo information from multiple objects. In the present study, we used echolocation sequences containing echoes from three, two or one object separated in the space depth as stimuli to study neuronal activity in the bat auditory cortex. Neuronal activity was recorded with multi-electrode arrays placed in the dorsal auditory cortex, where neurons tuned to target-distance are found. Our results show that target-distance encoding neurons are mostly selective to echoes coming from the closest object, and that the representation of echo information from distant objects is selectively suppressed. This suppression extends over a large part of the dorsal auditory cortex and may override possible parallel processing of multiple objects. The presented data suggest that global cortical suppression might establish a cortical “default mode” that allows selectively focusing on close obstacle even without active attention from the animals. PMID:27786252

Matched Behavioral and Neural Adaptations for Low Sound Level Echolocation in a Gleaning Bat, Antrozous pallidus.

PubMed

Measor, Kevin R; Leavell, Brian C; Brewton, Dustin H; Rumschlag, Jeffrey; Barber, Jesse R; Razak, Khaleel A

2017-01-01

In active sensing, animals make motor adjustments to match sensory inputs to specialized neural circuitry. Here, we describe an active sensing system for sound level processing. The pallid bat uses downward frequency-modulated (FM) sweeps as echolocation calls for general orientation and obstacle avoidance. The bat's auditory cortex contains a region selective for these FM sweeps (FM sweep-selective region, FMSR). We show that the vast majority of FMSR neurons are sensitive and strongly selective for relatively low levels (30-60 dB SPL). Behavioral testing shows that when a flying bat approaches a target, it reduces output call levels to keep echo levels between ∼30 and 55 dB SPL. Thus, the pallid bat behaviorally matches echo levels to an optimized neural representation of sound levels. FMSR neurons are more selective for sound levels of FM sweeps than tones, suggesting that across-frequency integration enhances level tuning. Level-dependent timing of high-frequency sideband inhibition in the receptive field shapes increased level selectivity for FM sweeps. Together with previous studies, these data indicate that the same receptive field properties shape multiple filters (sweep direction, rate, and level) for FM sweeps, a sound common in multiple vocalizations, including human speech. The matched behavioral and neural adaptations for low-intensity echolocation in the pallid bat will facilitate foraging with reduced probability of acoustic detection by prey.

Bats adjust their mouth gape to zoom their biosonar field of view

PubMed Central

Rydell, Jens; Amichai, Eran; Boonman, Arjan; Eitan, Ofri; Weiss, Anthony J.; Yovel, Yossi

2015-01-01

Active sensing, where sensory acquisition is actively modulated, is an inherent component of almost all sensory systems. Echolocating bats are a prime example of active sensing. They can rapidly adjust many of their biosonar parameters to optimize sensory acquisition. They dynamically adjust pulse design, pulse duration, and pulse rate within dozens of milliseconds according to the sensory information that is required for the task that they are performing. The least studied and least understood degree of freedom in echolocation is emission beamforming—the ability to change the shape of the sonar sound beam in a functional way. Such an ability could have a great impact on the bat’s control over its sensory perception. On the one hand, the bat could direct more energy into a narrow sector to zoom its biosonar field of view, and on the other hand, it could widen the beam to increase the space that it senses. We show that freely behaving bats constantly control their biosonar field of view in natural situations by rapidly adjusting their emitter aperture—the mouth gape. The bats dramatically narrowed the beam when entering a confined space, and they dramatically widened it within dozens of milliseconds when flying toward open space. Hence, mouth-emitting bats dynamically adjust their mouth gape to optimize the area that they sense with their echolocation system. PMID:25941395

Evolutionary escalation: the bat-moth arms race.

PubMed

Ter Hofstede, Hannah M; Ratcliffe, John M

2016-06-01

Echolocation in bats and high-frequency hearing in their insect prey make bats and insects an ideal system for studying the sensory ecology and neuroethology of predator-prey interactions. Here, we review the evolutionary history of bats and eared insects, focusing on the insect order Lepidoptera, and consider the evidence for antipredator adaptations and predator counter-adaptations. Ears evolved in a remarkable number of body locations across insects, with the original selection pressure for ears differing between groups. Although cause and effect are difficult to determine, correlations between hearing and life history strategies in moths provide evidence for how these two variables influence each other. We consider life history variables such as size, sex, circadian and seasonal activity patterns, geographic range and the composition of sympatric bat communities. We also review hypotheses on the neural basis for anti-predator behaviours (such as evasive flight and sound production) in moths. It is assumed that these prey adaptations would select for counter-adaptations in predatory bats. We suggest two levels of support for classifying bat traits as counter-adaptations: traits that allow bats to eat more eared prey than expected based on their availability in the environment provide a low level of support for counter-adaptations, whereas traits that have no other plausible explanation for their origination and maintenance than capturing defended prey constitute a high level of support. Specific predator counter-adaptations include calling at frequencies outside the sensitivity range of most eared prey, changing the pattern and frequency of echolocation calls during prey pursuit, and quiet, or 'stealth', echolocation. © 2016. Published by The Company of Biologists Ltd.

Adaptive Evolution of the Myo6 Gene in Old World Fruit Bats (Family: Pteropodidae)

PubMed Central

Shen, Bin; Han, Xiuqun; Jones, Gareth; Rossiter, Stephen J.; Zhang, Shuyi

2013-01-01

Myosin VI (encoded by the Myo6 gene) is highly expressed in the inner and outer hair cells of the ear, retina, and polarized epithelial cells such as kidney proximal tubule cells and intestinal enterocytes. The Myo6 gene is thought to be involved in a wide range of physiological functions such as hearing, vision, and clathrin-mediated endocytosis. Bats (Chiroptera) represent one of the most fascinating mammal groups for molecular evolutionary studies of the Myo6 gene. A diversity of specialized adaptations occur among different bat lineages, such as echolocation and associated high-frequency hearing in laryngeal echolocating bats, large eyes and a strong dependence on vision in Old World fruit bats (Pteropodidae), and specialized high-carbohydrate but low-nitrogen diets in both Old World and New World fruit bats (Phyllostomidae). To investigate what role(s) the Myo6 gene might fulfill in bats, we sequenced the coding region of the Myo6 gene in 15 bat species and used molecular evolutionary analyses to detect evidence of positive selection in different bat lineages. We also conducted real-time PCR assays to explore the expression levels of Myo6 in a range of tissues from three representative bat species. Molecular evolutionary analyses revealed that the Myo6 gene, which was widely considered as a hearing gene, has undergone adaptive evolution in the Old World fruit bats which lack laryngeal echolocation and associated high-frequency hearing. Real-time PCR showed the highest expression level of the Myo6 gene in the kidney among ten tissues examined in three bat species, indicating an important role for this gene in kidney function. We suggest that Myo6 has undergone adaptive evolution in Old World fruit bats in relation to receptor-mediated endocytosis for the preservation of protein and essential nutrients. PMID:23620821

Functional Organization and Dynamic Activity in the Superior Colliculus of the Echolocating Bat, Eptesicus fuscus.

PubMed

Wohlgemuth, Melville J; Kothari, Ninad B; Moss, Cynthia F

2018-01-03

Sensory-guided behaviors require the transformation of sensory information into task-specific motor commands. Prior research on sensorimotor integration has emphasized visuomotor processes in the context of simplified orienting movements in controlled laboratory tasks rather than an animal's more complete, natural behavioral repertoire. Here, we conducted a series of neural recording experiments in the midbrain superior colliculus (SC) of echolocating bats engaged in a sonar target-tracking task that invoked dynamic active sensing behaviors. We hypothesized that SC activity in freely behaving animals would reveal dynamic shifts in neural firing patterns within and across sensory, sensorimotor, and premotor layers. We recorded neural activity in the SC of freely echolocating bats (three females and one male) and replicated the general trends reported in other species with sensory responses in the dorsal divisions and premotor activity in ventral divisions of the SC. However, within this coarse functional organization, we discovered that sensory and motor neurons are comingled within layers throughout the volume of the bat SC. In addition, as the bat increased pulse rate adaptively to increase resolution of the target location with closing distance, the activity of sensory and vocal premotor neurons changed such that auditory response times decreased, and vocal premotor lead times shortened. This finding demonstrates that SC activity can be modified dynamically in concert with adaptive behaviors and suggests that an integrated functional organization within SC laminae supports rapid and local integration of sensory and motor signals for natural, adaptive behaviors. SIGNIFICANCE STATEMENT Natural sensory-guided behaviors involve the rapid integration of information from the environment to direct flexible motor actions. The vast majority of research on sensorimotor integration has used artificial stimuli and simplified behaviors, leaving open questions about nervous system function in the context of natural tasks. Our work investigated mechanisms of dynamic sensorimotor feedback control by analyzing patterns of neural activity in the midbrain superior colliculus (SC) of an echolocating bat tracking and intercepting moving prey. Recordings revealed that sensory and motor neurons comingle within laminae of the SC to support rapid sensorimotor integration. Further, we discovered that neural activity in the bat SC changes with dynamic adaptations in the animal's echolocation behavior. Copyright © 2018 the authors 0270-6474/18/380245-12$15.00/0.

Automatic gain control in the echolocation system of dolphins

NASA Astrophysics Data System (ADS)

Au, Whitlow W. L.; Benoit-Bird, Kelly J.

2003-06-01

In bats and technological sonars, the gain of the receiver is progressively increased with time after the transmission of a signal to compensate for acoustic propagation loss. The current understanding of dolphin echolocation indicates that automatic gain control is not a part of their sonar system. In order to test this understanding, we have performed field measurements of free-ranging echolocating dolphins. Here we show that dolphins do possess an automatic gain control mechanism, but that it is implemented in the transmission phase rather than the receiving phase of a sonar cycle. We find that the amplitude of the dolphins' echolocation signals are highly range dependent; this amplitude increases with increasing target range, R, in a 20log(R) fashion to compensate for propagation loss. If the echolocation target is a fish school with many sound scatterers, the echoes from the school will remain nearly constant with range as the dolphin closes in on it. This characteristic has the same effect as time-varying gain in bats and technological sonar when considered from a sonar system perspective.

Scaling of echolocation call parameters in bats.

PubMed

Jones, G

1999-12-01

I investigated the scaling of echolocation call parameters (frequency, duration and repetition rate) in bats in a functional context. Low-duty-cycle bats operate with search phase cycles of usually less than 20 %. They process echoes in the time domain and are therefore intolerant of pulse-echo overlap. High-duty-cycle (>30 %) species use Doppler shift compensation, and they separate pulse and echo in the frequency domain. Call frequency scales negatively with body mass in at least five bat families. Pulse duration scales positively with mass in low-duty-cycle quasi-constant-frequency (QCF) species because the large aerial-hawking species that emit these signals fly fast in open habitats. They therefore detect distant targets and experience pulse-echo overlap later than do smaller bats. Pulse duration also scales positively with mass in the Hipposideridae, which show at least partial Doppler shift compensation. Pulse repetition rate corresponds closely with wingbeat frequency in QCF bat species that fly relatively slowly. Larger, fast-flying species often skip pulses when detecting distant targets. There is probably a trade-off between call intensity and repetition rate because 'whispering' bats (and hipposiderids) produce several calls per predicted wingbeat and because batches of calls are emitted per wingbeat during terminal buzzes. Severe atmospheric attenuation at high frequencies limits the range of high-frequency calls. Low-duty-cycle bats that call at high frequencies must therefore use short pulses to avoid pulse-echo overlap. Rhinolophids escape this constraint by Doppler shift compensation and, importantly, can exploit advantages associated with the emission of both high-frequency and long-duration calls. Low frequencies are unsuited for the detection of small prey, and low repetition rates may limit prey detection rates. Echolocation parameters may therefore constrain maximum body size in aerial-hawking bats.

Divergence of dim-light vision among bats (order: Chiroptera) as estimated by molecular and electrophysiological methods

PubMed Central

Liu, He-Qun; Wei, Jing-Kuan; Li, Bo; Wang, Ming-Shan; Wu, Rui-Qi; Rizak, Joshua D.; Zhong, Li; Wang, Lu; Xu, Fu-Qiang; Shen, Yong-Yi; Hu, Xin-Tian; Zhang, Ya-Ping

2015-01-01

Dim-light vision is present in all bats, but is divergent among species. Old-World fruit bats (Pteropodidae) have fully developed eyes; the eyes of insectivorous bats are generally degraded, and these bats rely on well-developed echolocation. An exception is the Emballonuridae, which are capable of laryngeal echolocation but prefer to use vision for navigation and have normal eyes. In this study, integrated methods, comprising manganese-enhanced magnetic resonance imaging (MEMRI), f-VEP and RNA-seq, were utilized to verify the divergence. The results of MEMRI showed that Pteropodidae bats have a much larger superior colliculus (SC)/ inferior colliculus (IC) volume ratio (3:1) than insectivorous bats (1:7). Furthermore, the absolute visual thresholds (log cd/m2•s) of Pteropodidae (−6.30 and −6.37) and Emballonuridae (−3.71) bats were lower than those of other insectivorous bats (−1.90). Finally, genes related to the visual pathway showed signs of positive selection, convergent evolution, upregulation and similar gene expression patterns in Pteropodidae and Emballonuridae bats. Different results imply that Pteropodidae and Emballonuridae bats have more developed vision than the insectivorous bats and suggest that further research on bat behavior is warranted. PMID:26100095

High levels of activity of bats at gold mining water bodies: implications for compliance with the International Cyanide Management Code.

PubMed

Griffiths, Stephen R; Donato, David B; Coulson, Graeme; Lumsden, Linda F

2014-06-01

Wildlife and livestock are known to visit and interact with tailings dam and other wastewater impoundments at gold mines. When cyanide concentrations within these water bodies exceed a critical toxicity threshold, significant cyanide-related mortality events can occur in wildlife. Highly mobile taxa such as birds are particularly susceptible to cyanide toxicosis. Nocturnally active bats have similar access to uncovered wastewater impoundments as birds; however, cyanide toxicosis risks to bats remain ambiguous. This study investigated activity of bats in the airspace above two water bodies at an Australian gold mine, to assess the extent to which bats use these water bodies and hence are at potential risk of exposure to cyanide. Bat activity was present on most nights sampled during the 16-month survey period, although it was highly variable across nights and months. Therefore, despite the artificial nature of wastewater impoundments at gold mines, these structures present attractive habitats to bats. As tailings slurry and supernatant pooling within the tailings dam were consistently well below the industry protective concentration limit of 50 mg/L weak acid dissociable (WAD) cyanide, wastewater solutions stored within the tailings dam posed a minimal risk of cyanide toxicosis for wildlife, including bats. This study showed that passively recorded bat echolocation call data provides evidence of the presence and relative activity of bats above water bodies at mine sites. Furthermore, echolocation buzz calls recorded in the airspace directly above water provide indirect evidence of foraging and/or drinking. Both echolocation monitoring and systematic sampling of cyanide concentration in open wastewater impoundments can be incorporated into a gold mine risk-assessment model in order to evaluate the risk of bat exposure to cyanide. In relation to risk minimisation management practices, the most effective mechanism for preventing cyanide toxicosis to wildlife, including bats, is capping the concentration of cyanide in tailings discharged to open impoundments at 50 mg/L WAD.

PRINCIPLES AND PATTERNS OF BAT MOVEMENTS: FROM AERODYNAMICS TO ECOLOGY

PubMed Central

Voigt, Christian C.; Frick, Winifred F.; Holderied, Marc W.; Holland, Richard; Kerth, Gerald; Mello, Marco A. R.; Plowright, Raina K.; Swartz, Sharon; Yovel, Yossi

2018-01-01

Movement ecology as an integrative discipline has advanced associated fields because it presents not only a conceptual framework for understanding movement principles but also helps formulate predictions about the consequences of movements for animals and their environments. Here, we synthesize recent studies on principles and patterns of bat movements in context of the movement ecology paradigm. The motion capacity of bats is defined by their highly articulated, flexible wings. Power production during flight follows a U-shaped curve in relation to speed in bats yet, in contrast to birds, bats use mostly exogenous nutrients for sustained flight. The navigation capacity of most bats is dominated by the echolocation system, yet other sensory modalities, including an iron-based magnetic sense, may contribute to navigation depending on a bat’s familiarity with the terrain. Patterns derived from these capacities relate to antagonistic and mutualistic interactions with food items. The navigation capacity of bats may influence their sociality, in particular, the extent of group foraging based on eavesdropping on conspecifics’ echolocation calls. We infer that understanding the movement ecology of bats within the framework of the movement ecology paradigm provides new insights into ecological processes mediated by bats, from ecosystem services to diseases. PMID:29861509

Place recognition using batlike sonar.

PubMed

Vanderelst, Dieter; Steckel, Jan; Boen, Andre; Peremans, Herbert; Holderied, Marc W

2016-08-02

Echolocating bats have excellent spatial memory and are able to navigate to salient locations using bio-sonar. Navigating and route-following require animals to recognize places. Currently, it is mostly unknown how bats recognize places using echolocation. In this paper, we propose template based place recognition might underlie sonar-based navigation in bats. Under this hypothesis, bats recognize places by remembering their echo signature - rather than their 3D layout. Using a large body of ensonification data collected in three different habitats, we test the viability of this hypothesis assessing two critical properties of the proposed echo signatures: (1) they can be uniquely classified and (2) they vary continuously across space. Based on the results presented, we conclude that the proposed echo signatures satisfy both criteria. We discuss how these two properties of the echo signatures can support navigation and building a cognitive map.

Hawkmoths produce anti-bat ultrasound

PubMed Central

Barber, Jesse R.; Kawahara, Akito Y.

2013-01-01

Bats and moths have been engaged in aerial warfare for nearly 65 Myr. This arms race has produced a suite of counter-adaptations in moths, including bat-detecting ears. One set of defensive strategies involves the active production of sound; tiger moths' ultrasonic replies to bat attack have been shown to startle bats, warn the predators of bad taste and jam their biosonar. Here, we report that hawkmoths in the Choerocampina produce entirely ultrasonic sounds in response to tactile stimulation and the playback of biosonar attack sequences. Males do so by grating modified scraper scales on the outer surface of the genital valves against the inner margin of the last abdominal tergum. Preliminary data indicate that females also produce ultrasound to touch and playback of echolocation attack, but they do so with an entirely different mechanism. The anti-bat function of these sounds is unknown but might include startling, cross-family acoustic mimicry, warning of unprofitability or physical defence and/or jamming of echolocation. Hawkmoths present a novel and tractable system to study both the function and evolution of anti-bat defences. PMID:23825084

The role of ecological factors in shaping bat cone opsin evolution.

PubMed

Gutierrez, Eduardo de A; Schott, Ryan K; Preston, Matthew W; Loureiro, Lívia O; Lim, Burton K; Chang, Belinda S W

2018-04-11

Bats represent one of the largest and most striking nocturnal mammalian radiations, exhibiting many visual system specializations for performance in light-limited environments. Despite representing the greatest ecological diversity and species richness in Chiroptera, Neotropical lineages have been undersampled in molecular studies, limiting the potential for identifying signatures of selection on visual genes associated with differences in bat ecology. Here, we investigated how diverse ecological pressures mediate long-term shifts in selection upon long-wavelength ( Lws ) and short-wavelength ( Sws1 ) opsins, photosensitive cone pigments that form the basis of colour vision in most mammals, including bats. We used codon-based likelihood clade models to test whether ecological variables associated with reliance on visual information (e.g. echolocation ability and diet) or exposure to varying light environments (e.g. roosting behaviour and foraging habitat) mediated shifts in evolutionary rates in bat cone opsin genes. Using additional cone opsin sequences from newly sequenced eye transcriptomes of six Neotropical bat species, we found significant evidence for different ecological pressures influencing the evolution of the cone opsins. While Lws is evolving under significantly lower constraint in highly specialized high-duty cycle echolocating lineages, which have enhanced sonar ability to detect and track targets, variation in Sws1 constraint was significantly associated with foraging habitat, exhibiting elevated rates of evolution in species that forage among vegetation. This suggests that increased reliance on echolocation as well as the spectral environment experienced by foraging bats may differentially influence the evolution of different cone opsins. Our study demonstrates that different ecological variables may underlie contrasting evolutionary patterns in bat visual opsins, and highlights the suitability of clade models for testing ecological hypotheses of visual evolution. © 2018 The Author(s).

Active Listening in a Bat Cocktail Party: Adaptive Echolocation and Flight Behaviors of Big Brown Bats, Eptesicus fuscus, Foraging in a Cluttered Acoustic Environment.

PubMed

Warnecke, Michaela; Chiu, Chen; Engelberg, Jonathan; Moss, Cynthia F

2015-09-01

In their natural environment, big brown bats forage for small insects in open spaces, as well as in vegetation and in the presence of acoustic clutter. While searching and hunting for prey, bats experience sonar interference, not only from densely cluttered environments, but also from calls of conspecifics foraging in close proximity. Previous work has shown that when two bats compete for a single prey item in a relatively open environment, one of the bats may go silent for extended periods of time, which can serve to minimize sonar interference between conspecifics. Additionally, pairs of big brown bats have been shown to adjust frequency characteristics of their vocalizations to avoid acoustic interference in echo processing. In this study, we extended previous work by examining how the presence of conspecifics and environmental clutter influence the bat's echolocation behavior. By recording multichannel audio and video data of bats engaged in insect capture in open and cluttered spaces, we quantified the bats' vocal and flight behaviors. Big brown bats flew individually and in pairs in an open and cluttered room, and the results of this study shed light on the different strategies that this species employs to negotiate a complex and dynamic environment. © 2015 S. Karger AG, Basel.

Effects of competitive prey capture on flight behavior and sonar beam pattern in paired big brown bats, Eptesicus fuscus.

PubMed

Chiu, Chen; Reddy, Puduru Viswanadha; Xian, Wei; Krishnaprasad, Perinkulam S; Moss, Cynthia F

2010-10-01

Foraging and flight behavior of echolocating bats were quantitatively analyzed in this study. Paired big brown bats, Eptesicus fuscus, competed for a single food item in a large laboratory flight room. Their sonar beam patterns and flight paths were recorded by a microphone array and two high-speed cameras, respectively. Bats often remained in nearly classical pursuit (CP) states when one bat is following another bat. A follower can detect and anticipate the movement of the leader, while the leader has the advantage of gaining access to the prey first. Bats in the trailing position throughout the trial were more successful in accessing the prey. In this study, bats also used their sonar beam to monitor the conspecific's movement and to track the prey. Each bat tended to use its sonar beam to track the prey when it was closer to the worm than to another bat. The trailing bat often directed its sonar beam toward the leading bat in following flight. When two bats flew towards each other, they tended to direct their sonar beam axes away from each other, presumably to avoid signal jamming. This study provides a new perspective on how echolocating bats use their biosonar system to coordinate their flight with conspecifics in a group and how they compete for the same food source with conspecifics.

Sensory Biology: Acoustic Reflectors Attract Bats to Roost in Pitcher Plants.

PubMed

Jones, Gareth

2015-07-20

A new study shows that a carnivorous plant attracts bats by possessing modified pitfall taps that increase the reflectivity of echolocation calls. Bats benefit by finding roosting sites, and the plants gain by receiving nitrogen from guano. Copyright © 2015 Elsevier Ltd. All rights reserved.

Matched Behavioral and Neural Adaptations for Low Sound Level Echolocation in a Gleaning Bat, Antrozous pallidus

PubMed Central

Measor, Kevin R.; Leavell, Brian C.; Brewton, Dustin H.; Rumschlag, Jeffrey; Barber, Jesse R.

2017-01-01

Abstract In active sensing, animals make motor adjustments to match sensory inputs to specialized neural circuitry. Here, we describe an active sensing system for sound level processing. The pallid bat uses downward frequency-modulated (FM) sweeps as echolocation calls for general orientation and obstacle avoidance. The bat’s auditory cortex contains a region selective for these FM sweeps (FM sweep-selective region, FMSR). We show that the vast majority of FMSR neurons are sensitive and strongly selective for relatively low levels (30-60 dB SPL). Behavioral testing shows that when a flying bat approaches a target, it reduces output call levels to keep echo levels between ∼30 and 55 dB SPL. Thus, the pallid bat behaviorally matches echo levels to an optimized neural representation of sound levels. FMSR neurons are more selective for sound levels of FM sweeps than tones, suggesting that across-frequency integration enhances level tuning. Level-dependent timing of high-frequency sideband inhibition in the receptive field shapes increased level selectivity for FM sweeps. Together with previous studies, these data indicate that the same receptive field properties shape multiple filters (sweep direction, rate, and level) for FM sweeps, a sound common in multiple vocalizations, including human speech. The matched behavioral and neural adaptations for low-intensity echolocation in the pallid bat will facilitate foraging with reduced probability of acoustic detection by prey. PMID:28275715

The role of tragus on echolocating bat, Eptesicus fuscus

NASA Astrophysics Data System (ADS)

Chiu, Chen; Moss, Cynthia

2005-04-01

Echolocating bats produce ultrasonic vocal signals and utilize the returning echoes to detect, localize and track prey, and also to avoid obstacles. The pinna and tragus, two major components of the bats external ears, play important roles in filtering returning echoes. The tragus is generally believed to play a role in vertical sound localization. The purpose of this study is to further examine how manipulation of the tragus affects a free-flying bat's prey capture and obstacle avoidance behavior. The first part of this study involved a prey capture experiment, and the bat was trained to catch the tethered mealworms in a large room. The second experiment involved obstacle avoidance, and the bat's task was to fly through the largest opening from a horizontal wire array without touching the wires. In both experiments, the bat performed the tasks under three different conditions: with intact tragus, tragus-deflection and recovery from tragus-deflection. Significantly lower performance was observed in both experiments when tragi were glued down. However, the bat adjusted quickly and returned to baseline performance a few days after the manipulation. The results suggest that tragus-deflection does have effects on both the prey capture and obstacle avoidance behavior. [Work supported by NSF.

Wind turbines and bat mortality: Doppler shift profiles and ultrasonic bat-like pulse reflection from moving turbine blades.

PubMed

Long, Chloe V; Flint, James A; Lepper, Paul A

2010-10-01

Bat mortality resulting from actual or near-collision with operational wind turbine rotors is a phenomenon that is widespread but not well understood. Because bats rely on information contained in high-frequency echoes to determine the nature and movement of a target, it is important to consider how ultrasonic pulses similar to those used by bats for echolocation may be interacting with operational turbine rotor blades. By assessing the characteristics of reflected ultrasonic echoes, moving turbine blades operating under low wind speed conditions (<6 m s(-1)) were found to produce distinct Doppler shift profiles at different angles to the rotor. Frequency shifts of up to ±700-800 Hz were produced, which may not be perceptible by some bat species. Monte Carlo simulation of bat-like sampling by echolocation revealed that over 50 rotor echoes could be required by species such as Pipistrellus pipistrellus for accurate interpretation of blade movement, which may not be achieved in the bat's approach time-window. In summary, it was found that echoes returned from moving blades had features which could render them attractive to bats or which might make it difficult for the bat to accurately detect and locate blades in sufficient time to avoid a collision.

Morphological correlates of echolocation frequency in the endemic Cape horseshoe bat, Rhinolophus capensis (Chiroptera: Rhinolophidae).

PubMed

Odendaal, Lizelle J; Jacobs, David S

2011-05-01

We investigated intraspecific variation in echolocation calls of the Cape horseshoe bat, Rhinolophus capensis, by comparing echolocation and associated morphological parameters among individuals from three populations of this species. The populations were situated in the center and at the western and eastern limits of the distribution of R. capensis. The latter two populations were situated in ecotones between vegetation biomes. Ecotone populations deviated slightly from the allometric relationship between body size and peak frequency for the genus, and there was no relationship between these variables within R. capensis. Nasal chamber length was the best predictor of peak frequency but not correlated with body size. The evolution of echolocation thus appears to have been uncoupled from body size in R. capensis. Furthermore, females used higher frequencies than males, which imply a potential social role for peak frequency. The differences in peak frequency may have originated from random founder effects and then compounded by genetic drift and/or natural selection. The latter may have acted directly on peak frequency altering skull parameters involved in echolocation independently of body size, resulting in the evolution of local acoustic signatures.

Do you hear what I see? Vocalization relative to visual detection rates of Hawaiian hoary bats (Lasiurus cinereus semotus)

USGS Publications Warehouse

Gorresen, Paulo Marcos; Cryan, Paul; Montoya-Aiona, Kristina; Bonaccorso, Frank

2017-01-01

Bats vocalize during flight as part of the sensory modality called echolocation, but very little is known about whether flying bats consistently call. Occasional vocal silence during flight when bats approach prey or conspecifics has been documented for relatively few species and situations. Bats flying alone in clutter-free airspace are not known to forgo vocalization, yet prior observations suggested possible silent behavior in certain, unexpected situations. Determining when, why, and where silent behavior occurs in bats will help evaluate major assumptions of a primary monitoring method for bats used in ecological research, management, and conservation. In this study, we recorded flight activity of Hawaiian hoary bats (Lasiurus cinereus semotus) under seminatural conditions using both thermal video cameras and acoustic detectors. Simultaneous video and audio recordings from 20 nights of observation at 10 sites were analyzed for correspondence between detection methods, with a focus on video observations in three distance categories for which accompanying vocalizations were detected. Comparison of video and audio detections revealed that a high proportion of Hawaiian hoary bats “seen” on video were not simultaneously “heard.” On average, only about one in three visual detections within a night had an accompanying call detection, but this varied greatly among nights. Bats flying on curved flight paths and individuals nearer the cameras were more likely to be detected by both methods. Feeding and social calls were detected, but no clear pattern emerged from the small number of observations involving closely interacting bats. These results may indicate that flying Hawaiian hoary bats often forgo echolocation, or do not always vocalize in a way that is detectable with common sampling and monitoring methods. Possible reasons for the low correspondence between visual and acoustic detections range from methodological to biological and include a number of biases associated with the propagation and detection of sound, cryptic foraging strategies, or conspecific presence. Silent flight behavior may be more prevalent in echolocating bats than previously appreciated, has profound implications for ecological research, and deserves further characterization and study.

Place recognition using batlike sonar

PubMed Central

Vanderelst, Dieter; Steckel, Jan; Boen, Andre; Peremans, Herbert; Holderied, Marc W

2016-01-01

Echolocating bats have excellent spatial memory and are able to navigate to salient locations using bio-sonar. Navigating and route-following require animals to recognize places. Currently, it is mostly unknown how bats recognize places using echolocation. In this paper, we propose template based place recognition might underlie sonar-based navigation in bats. Under this hypothesis, bats recognize places by remembering their echo signature - rather than their 3D layout. Using a large body of ensonification data collected in three different habitats, we test the viability of this hypothesis assessing two critical properties of the proposed echo signatures: (1) they can be uniquely classified and (2) they vary continuously across space. Based on the results presented, we conclude that the proposed echo signatures satisfy both criteria. We discuss how these two properties of the echo signatures can support navigation and building a cognitive map. DOI: http://dx.doi.org/10.7554/eLife.14188.001 PMID:27481189

Dynamic adjustment of echolocation pulse structure of big-footed myotis (Myotis macrodactylus) in response to different habitats.

PubMed

Wang, Lei; Luo, Jinhong; Wang, Hongna; Ou, Wei; Jiang, Tinglei; Liu, Ying; Lyle, Dennis; Feng, Jiang

2014-02-01

Studying relationships between characteristics of sonar pulses and habitat clutter level is important for the understanding of signal design in bat echolocation. However, most studies have focused on overall spectral and temporal parameters of such vocalizations, with focus less on potential variation in frequency modulation rates (MRs) occurring within each pulse. In the current study, frequency modulation (FM) characteristics were examined in echolocation pulses recorded from big-footed myotis (Myotis macrodactylus) bats as these animals searched for prey in five habitats differing in relative clutter level. Pulses were analyzed using ten parameters, including four structure-related characters which were derived by dividing each pulse into three elements based on two knees in the FM sweep. Results showed that overall frequency, pulse duration, and MR all varied across habitat. The strongest effects were found for MR in the body of the pulse, implying that this particular component plays a major role as M. macrodactylus, and potentially other bat species, adjust to varying clutter levels in their foraging habitats.

Multi-component separation and analysis of bat echolocation calls.

PubMed

DiCecco, John; Gaudette, Jason E; Simmons, James A

2013-01-01

The vast majority of animal vocalizations contain multiple frequency modulated (FM) components with varying amounts of non-linear modulation and harmonic instability. This is especially true of biosonar sounds where precise time-frequency templates are essential for neural information processing of echoes. Understanding the dynamic waveform design by bats and other echolocating animals may help to improve the efficacy of man-made sonar through biomimetic design. Bats are known to adapt their call structure based on the echolocation task, proximity to nearby objects, and density of acoustic clutter. To interpret the significance of these changes, a method was developed for component separation and analysis of biosonar waveforms. Techniques for imaging in the time-frequency plane are typically limited due to the uncertainty principle and interference cross terms. This problem is addressed by extending the use of the fractional Fourier transform to isolate each non-linear component for separate analysis. Once separated, empirical mode decomposition can be used to further examine each component. The Hilbert transform may then successfully extract detailed time-frequency information from each isolated component. This multi-component analysis method is applied to the sonar signals of four species of bats recorded in-flight by radiotelemetry along with a comparison of other common time-frequency representations.

A deterministic compressive sensing model for bat biosonar.

PubMed

Hague, David A; Buck, John R; Bilik, Igal

2012-12-01

The big brown bat (Eptesicus fuscus) uses frequency modulated (FM) echolocation calls to accurately estimate range and resolve closely spaced objects in clutter and noise. They resolve glints spaced down to 2 μs in time delay which surpasses what traditional signal processing techniques can achieve using the same echolocation call. The Matched Filter (MF) attains 10-12 μs resolution while the Inverse Filter (IF) achieves higher resolution at the cost of significantly degraded detection performance. Recent work by Fontaine and Peremans [J. Acoustic. Soc. Am. 125, 3052-3059 (2009)] demonstrated that a sparse representation of bat echolocation calls coupled with a decimating sensing method facilitates distinguishing closely spaced objects over realistic SNRs. Their work raises the intriguing question of whether sensing approaches structured more like a mammalian auditory system contains the necessary information for the hyper-resolution observed in behavioral tests. This research estimates sparse echo signatures using a gammatone filterbank decimation sensing method which loosely models the processing of the bat's auditory system. The decimated filterbank outputs are processed with [script-l](1) minimization. Simulations demonstrate that this model maintains higher resolution than the MF and significantly better detection performance than the IF for SNRs of 5-45 dB while undersampling the return signal by a factor of six.

The effect of climate on acoustic signals: does atmospheric sound absorption matter for bird song and bat echolocation?

PubMed

Snell-Rood, Emilie C

2012-02-01

The divergence of signals along ecological gradients may lead to speciation. The current research tests the hypothesis that variation in sound absorption selects for divergence in acoustic signals along climatic gradients, which has implications for understanding not only diversification, but also how organisms may respond to climate change. Because sound absorption varies with temperature, humidity, and the frequency of sound, individuals or species may vary signal structure with changes in climate over space or time. In particular, signals of lower frequency, narrower bandwidth, and longer duration should be more detectable in environments with high sound absorption. Using both North American wood warblers (Parulidae) and bats of the American Southwest, this work found evidence of associations between signal structure and sound absorption. Warbler species with higher mean absorption across their range were more likely to have narrow bandwidth songs. Bat species found in higher absorption habitats were more likely to have lower frequency echolocation calls. In addition, bat species changed echolocation call structure across seasons, using longer duration, lower frequency calls in the higher absorption rainy season. These results suggest that signals may diverge along climatic gradients due to variation in sound absorption, although the effects of absorption are modest. © 2012 Acoustical Society of America

Correlated evolution between hearing sensitivity and social calls in bats

PubMed Central

Bohn, Kirsten M; Moss, Cynthia F; Wilkinson, Gerald S

2006-01-01

Echolocating bats are auditory specialists, with exquisite hearing that spans several octaves. In the ultrasonic range, bat audiograms typically show highest sensitivity in the spectral region of their species-specific echolocation calls. Well-developed hearing in the audible range has been commonly attributed to a need to detect sounds produced by prey. However, bat pups often emit isolation calls with low-frequency components that facilitate mother–young reunions. In this study, we examine whether low-frequency hearing in bats exhibits correlated evolution with (i) body size; (ii) high-frequency hearing sensitivity or (iii) pup isolation call frequency. Using published audiograms, we found that low-frequency hearing sensitivity is not dependent on body size but is related to high-frequency hearing. After controlling for high-frequency hearing, we found that low-frequency hearing exhibits correlated evolution with isolation call frequency. We infer that detection and discrimination of isolation calls have favoured enhanced low-frequency hearing because accurate parental investment is critical: bats have low reproductive rates, non-volant altricial young and must often identify their pups within large crèches. PMID:17148288

Neurodynamics for auditory stream segregation: tracking sounds in the mustached bat's natural environment.

PubMed

Kanwal, Jagmeet S; Medvedev, Andrei V; Micheyl, Christophe

2003-08-01

During navigation and the search phase of foraging, mustached bats emit approximately 25 ms long echolocation pulses (at 10-40 Hz) that contain multiple harmonics of a constant frequency (CF) component followed by a short (3 ms) downward frequency modulation. In the context of auditory stream segregation, therefore, bats may either perceive a coherent pulse-echo sequence (PEPE...), or segregated pulse and echo streams (P-P-P... and E-E-E...). To identify the neural mechanisms for stream segregation in bats, we developed a simple yet realistic neural network model with seven layers and 420 nodes. Our model required recurrent and lateral inhibition to enable output nodes in the network to 'latch-on' to a single tone (corresponding to a CF component in either the pulse or echo), i.e., exhibit differential suppression by the alternating two tones presented at a high rate (> 10 Hz). To test the applicability of our model to echolocation, we obtained neurophysiological data from the primary auditory cortex of awake mustached bats. Event-related potentials reliably reproduced the latching behaviour observed at output nodes in the network. Pulse as well as nontarget (clutter) echo CFs facilitated this latching. Individual single unit responses were erratic, but when summed over several recording sites, they also exhibited reliable latching behaviour even at 40 Hz. On the basis of these findings, we propose that a neural correlate of auditory stream segregation is present within localized synaptic activity in the mustached bat's auditory cortex and this mechanism may enhance the perception of echolocation sounds in the natural environment.

Adaptive evolution of tight junction protein claudin-14 in echolocating whales.

PubMed

Xu, Huihui; Liu, Yang; He, Guimei; Rossiter, Stephen J; Zhang, Shuyi

2013-11-10

Toothed whales and bats have independently evolved specialized ultrasonic hearing for echolocation. Recent findings have suggested that several genes including Prestin, Tmc1, Pjvk and KCNQ4 appear to have undergone molecular adaptations associated with the evolution of this ultrasonic hearing in mammals. Here we studied the hearing gene Cldn14, which encodes the claudin-14 protein and is a member of tight junction proteins that functions in the organ of Corti in the inner ear to maintain a cationic gradient between endolymph and perilymph. Particular mutations in human claudin-14 give rise to non-syndromic deafness, suggesting an essential role in hearing. Our results uncovered two bursts of positive selection, one in the ancestral branch of all toothed whales and a second in the branch leading to the delphinid, phocoenid and ziphiid whales. These two branches are the same as those previously reported to show positive selection in the Prestin gene. Furthermore, as with Prestin, the estimated hearing frequencies of whales significantly correlate with numbers of branch-wise non-synonymous substitutions in Cldn14, but not with synonymous changes. However, in contrast to Prestin, we found no evidence of positive selection in bats. Our findings from Cldn14, and comparisons with Prestin, strongly implicate multiple loci in the acquisition of echolocation in cetaceans, but also highlight possible differences in the evolutionary route to echolocation taken by whales and bats. © 2013.

Timing matters: sonar call groups facilitate target localization in bats.

PubMed

Kothari, Ninad B; Wohlgemuth, Melville J; Hulgard, Katrine; Surlykke, Annemarie; Moss, Cynthia F

2014-01-01

To successfully negotiate a cluttered environment, an echolocating bat must control the timing of motor behaviors in response to dynamic sensory information. Here we detail the big brown bat's adaptive temporal control over sonar call production for tracking prey, moving predictably or unpredictably, under different experimental conditions. We studied the adaptive control of vocal-motor behaviors in free-flying big brown bats, Eptesicus fuscus, as they captured tethered and free-flying insects, in open and cluttered environments. We also studied adaptive sonar behavior in bats trained to track moving targets from a resting position. In each of these experiments, bats adjusted the features of their calls to separate target and clutter. Under many task conditions, flying bats produced prominent sonar sound groups identified as clusters of echolocation pulses with relatively stable intervals, surrounded by longer pulse intervals. In experiments where bats tracked approaching targets from a resting position, bats also produced sonar sound groups, and the prevalence of these sonar sound groups increased when motion of the target was unpredictable. We hypothesize that sonar sound groups produced during flight, and the sonar call doublets produced by a bat tracking a target from a resting position, help the animal resolve dynamic target location and represent the echo scene in greater detail. Collectively, our data reveal adaptive temporal control over sonar call production that allows the bat to negotiate a complex and dynamic environment.

Timing matters: sonar call groups facilitate target localization in bats

PubMed Central

Kothari, Ninad B.; Wohlgemuth, Melville J.; Hulgard, Katrine; Surlykke, Annemarie; Moss, Cynthia F.

2014-01-01

To successfully negotiate a cluttered environment, an echolocating bat must control the timing of motor behaviors in response to dynamic sensory information. Here we detail the big brown bat's adaptive temporal control over sonar call production for tracking prey, moving predictably or unpredictably, under different experimental conditions. We studied the adaptive control of vocal-motor behaviors in free-flying big brown bats, Eptesicus fuscus, as they captured tethered and free-flying insects, in open and cluttered environments. We also studied adaptive sonar behavior in bats trained to track moving targets from a resting position. In each of these experiments, bats adjusted the features of their calls to separate target and clutter. Under many task conditions, flying bats produced prominent sonar sound groups identified as clusters of echolocation pulses with relatively stable intervals, surrounded by longer pulse intervals. In experiments where bats tracked approaching targets from a resting position, bats also produced sonar sound groups, and the prevalence of these sonar sound groups increased when motion of the target was unpredictable. We hypothesize that sonar sound groups produced during flight, and the sonar call doublets produced by a bat tracking a target from a resting position, help the animal resolve dynamic target location and represent the echo scene in greater detail. Collectively, our data reveal adaptive temporal control over sonar call production that allows the bat to negotiate a complex and dynamic environment. PMID:24860509

Vespertilionid bats control the width of their biosonar sound beam dynamically during prey pursuit

PubMed Central

Jakobsen, Lasse; Surlykke, Annemarie

2010-01-01

Animals using sound for communication emit directional signals, focusing most acoustic energy in one direction. Echolocating bats are listening for soft echoes from insects. Therefore, a directional biosonar sound beam greatly increases detection probability in the forward direction and decreases off-axis echoes. However, high directionality has context-specific disadvantages: at close range the detection space will be vastly reduced, making a broad beam favorable. Hence, a flexible system would be very advantageous. We investigated whether bats can dynamically change directionality of their biosonar during aerial pursuit of insects. We trained five Myotis daubentonii and one Eptesicus serotinus to capture tethered mealworms and recorded their echolocation signals with a multimicrophone array. The results show that the bats broaden the echolocation beam drastically in the terminal phase of prey pursuit. M. daubentonii increased the half-amplitude angle from approximately 40° to approximately 90° horizontally and from approximately 45° to more than 90° vertically. The increase in beam width is achieved by lowering the frequency by roughly one octave from approximately 55 kHz to approximately 27.5 kHz. The E. serotinus showed beam broadening remarkably similar to that of M. daubentonii. Our results demonstrate dynamic control of beam width in both species. Hence, we propose directionality as an explanation for the frequency decrease observed in the buzz of aerial hawking vespertilionid bats. We predict that future studies will reveal dynamic control of beam width in a broad range of acoustically communicating animals. PMID:20643943

Vespertilionid bats control the width of their biosonar sound beam dynamically during prey pursuit.

PubMed

Jakobsen, Lasse; Surlykke, Annemarie

2010-08-03

Animals using sound for communication emit directional signals, focusing most acoustic energy in one direction. Echolocating bats are listening for soft echoes from insects. Therefore, a directional biosonar sound beam greatly increases detection probability in the forward direction and decreases off-axis echoes. However, high directionality has context-specific disadvantages: at close range the detection space will be vastly reduced, making a broad beam favorable. Hence, a flexible system would be very advantageous. We investigated whether bats can dynamically change directionality of their biosonar during aerial pursuit of insects. We trained five Myotis daubentonii and one Eptesicus serotinus to capture tethered mealworms and recorded their echolocation signals with a multimicrophone array. The results show that the bats broaden the echolocation beam drastically in the terminal phase of prey pursuit. M. daubentonii increased the half-amplitude angle from approximately 40 degrees to approximately 90 degrees horizontally and from approximately 45 degrees to more than 90 degrees vertically. The increase in beam width is achieved by lowering the frequency by roughly one octave from approximately 55 kHz to approximately 27.5 kHz. The E. serotinus showed beam broadening remarkably similar to that of M. daubentonii. Our results demonstrate dynamic control of beam width in both species. Hence, we propose directionality as an explanation for the frequency decrease observed in the buzz of aerial hawking vespertilionid bats. We predict that future studies will reveal dynamic control of beam width in a broad range of acoustically communicating animals.

No evidence for spectral jamming avoidance in echolocation behavior of foraging pipistrelle bats

PubMed Central

Götze, Simone; Koblitz, Jens C.; Denzinger, Annette; Schnitzler, Hans-Ulrich

2016-01-01

Frequency shifts in signals of bats flying near conspecifics have been interpreted as a spectral jamming avoidance response (JAR). However, several prerequisites supporting a JAR hypothesis have not been controlled for in previous studies. We recorded flight and echolocation behavior of foraging Pipistrellus pipistrellus while flying alone and with a conspecific and tested whether frequency changes were due to a spectral JAR with an increased frequency difference, or whether changes could be explained by other reactions. P. pipistrellus reacted to conspecifics with a reduction of sound duration and often also pulse interval, accompanied by an increase in terminal frequency. This reaction is typical of behavioral situations where targets of interest have captured the bat’s attention and initiated a more detailed exploration. All observed frequency changes were predicted by the attention reaction alone, and do not support the JAR hypothesis of increased frequency separation. Reaction distances of 1–11 m suggest that the attention response may be elicited either by detection of the conspecific by short range active echolocation or by long range passive acoustic detection of echolocation calls. PMID:27502900

Effects of Orientation and Weatherproofing on the Detection of Bat Echolocation Calls

Treesearch

E. Britzke; B. Slack; M Armstrong; S. Loeb

2010-01-01

Ultrasonic detectors are powerful tools for the study of bat ecology. Many options are available for deploying acoustic detectors including various weatherproofing designs and microphone orientations, but the impacts of these options on the quantity and quality of the bat calls that are recorded are unknown. We compared the impacts of three microphone orientations (...

Insight on how fishing bats discern prey and adjust their mechanic and sensorial features during the attack sequence

PubMed Central

Aizpurua, Ostaizka; Alberdi, Antton; Aihartza, Joxerra; Garin, Inazio

2015-01-01

Several insectivorous bats have included fish in their diet, yet little is known about the processes underlying this trophic shift. We performed three field experiments with wild fishing bats to address how they manage to discern fish from insects and adapt their hunting technique to capture fish. We show that bats react only to targets protruding above the water and discern fish from insects based on prey disappearance patterns. Stationary fish trigger short and shallow dips and a terminal echolocation pattern with an important component of the narrowband and low frequency calls. When the fish disappears during the attack process, bats regulate their attack increasing the number of broadband and high frequency calls in the last phase of the echolocation as well as by lengthening and deepening their dips. These adjustments may allow bats to obtain more valuable sensorial information and to perform dips adjusted to the level of uncertainty on the location of the submerged prey. The observed ultrafast regulation may be essential for enabling fishing to become cost-effective in bats, and demonstrates the ability of bats to rapidly modify and synchronise their sensorial and motor features as a response to last minute stimulus variations. PMID:26196094

Sound localization by echolocating bats

NASA Astrophysics Data System (ADS)

Aytekin, Murat

Echolocating bats emit ultrasonic vocalizations and listen to echoes reflected back from objects in the path of the sound beam to build a spatial representation of their surroundings. Important to understanding the representation of space through echolocation are detailed studies of the cues used for localization, the sonar emission patterns and how this information is assembled. This thesis includes three studies, one on the directional properties of the sonar receiver, one on the directional properties of the sonar transmitter, and a model that demonstrates the role of action in building a representation of auditory space. The general importance of this work to a broader understanding of spatial localization is discussed. Investigations of the directional properties of the sonar receiver reveal that interaural level difference and monaural spectral notch cues are both dependent on sound source azimuth and elevation. This redundancy allows flexibility that an echolocating bat may need when coping with complex computational demands for sound localization. Using a novel method to measure bat sonar emission patterns from freely behaving bats, I show that the sonar beam shape varies between vocalizations. Consequently, the auditory system of a bat may need to adapt its computations to accurately localize objects using changing acoustic inputs. Extra-auditory signals that carry information about pinna position and beam shape are required for auditory localization of sound sources. The auditory system must learn associations between extra-auditory signals and acoustic spatial cues. Furthermore, the auditory system must adapt to changes in acoustic input that occur with changes in pinna position and vocalization parameters. These demands on the nervous system suggest that sound localization is achieved through the interaction of behavioral control and acoustic inputs. A sensorimotor model demonstrates how an organism can learn space through auditory-motor contingencies. The model also reveals how different aspects of sound localization, such as experience-dependent acquisition, adaptation, and extra-auditory influences, can be brought together under a comprehensive framework. This thesis presents a foundation for understanding the representation of auditory space that builds upon acoustic cues, motor control, and learning dynamic associations between action and auditory inputs.

Environmental acoustic cues guide the biosonar attention of a highly specialised echolocator.

PubMed

Lattenkamp, Ella Z; Kaiser, Samuel; Kaučič, Rožle; Großmann, Martina; Koselj, Klemen; Goerlitz, Holger R

2018-04-23

Sensory systems experience a trade-off between maximizing the detail and amount of sampled information. This trade-off is particularly pronounced in sensory systems that are highly specialised for a single task and thus experience limitations in other tasks. We hypothesised that combining sensory input from multiple streams of information may resolve this trade-off and improve detection and sensing reliability. Specifically, we predicted that perceptive limitations experienced by animals reliant on specialised active echolocation can be compensated for by the phylogenetically older and less specialised process of passive hearing. We tested this hypothesis in greater horseshoe bats, which possess morphological and neural specialisations allowing them to identify fluttering prey in dense vegetation using echolocation only. At the same time, their echolocation system is both spatially and temporally severely limited. Here, we show that greater horseshoe bats employ passive hearing to initially detect and localise prey-generated and other environmental sounds, and then raise vocalisation level and concentrate the scanning movements of their sonar beam on the sound source for further investigation with echolocation. These specialised echolocators thus supplement echo-acoustic information with environmental acoustic cues, enlarging perceived space beyond their biosonar range. Contrary to our predictions, we did not find consistent preferences for prey-related acoustic stimuli, indicating the use of passive acoustic cues also for detection of non-prey objects. Our findings suggest that even specialised echolocators exploit a wide range of environmental information, and that phylogenetically older sensory systems can support the evolution of sensory specialisations by compensating for their limitations. © 2018. Published by The Company of Biologists Ltd.

Divergent evolutionary rates in vertebrate and mammalian specific conserved non-coding elements (CNEs) in echolocating mammals.

PubMed

Davies, Kalina T J; Tsagkogeorga, Georgia; Rossiter, Stephen J

2014-12-19

The majority of DNA contained within vertebrate genomes is non-coding, with a certain proportion of this thought to play regulatory roles during development. Conserved Non-coding Elements (CNEs) are an abundant group of putative regulatory sequences that are highly conserved across divergent groups and thus assumed to be under strong selective constraint. Many CNEs may contain regulatory factor binding sites, and their frequent spatial association with key developmental genes - such as those regulating sensory system development - suggests crucial roles in regulating gene expression and cellular patterning. Yet surprisingly little is known about the molecular evolution of CNEs across diverse mammalian taxa or their role in specific phenotypic adaptations. We examined 3,110 vertebrate-specific and ~82,000 mammalian-specific CNEs across 19 and 9 mammalian orders respectively, and tested for changes in the rate of evolution of CNEs located in the proximity of genes underlying the development or functioning of auditory systems. As we focused on CNEs putatively associated with genes underlying the development/functioning of auditory systems, we incorporated echolocating taxa in our dataset because of their highly specialised and derived auditory systems. Phylogenetic reconstructions of concatenated CNEs broadly recovered accepted mammal relationships despite high levels of sequence conservation. We found that CNE substitution rates were highest in rodents and lowest in primates, consistent with previous findings. Comparisons of CNE substitution rates from several genomic regions containing genes linked to auditory system development and hearing revealed differences between echolocating and non-echolocating taxa. Wider taxonomic sampling of four CNEs associated with the homeobox genes Hmx2 and Hmx3 - which are required for inner ear development - revealed family-wise variation across diverse bat species. Specifically within one family of echolocating bats that utilise frequency-modulated echolocation calls varying widely in frequency and intensity high levels of sequence divergence were found. Levels of selective constraint acting on CNEs differed both across genomic locations and taxa, with observed variation in substitution rates of CNEs among bat species. More work is needed to determine whether this variation can be linked to echolocation, and wider taxonomic sampling is necessary to fully document levels of conservation in CNEs across diverse taxa.

Determinants of echolocation call frequency variation in the Formosan lesser horseshoe bat (Rhinolophus monoceros)

PubMed Central

Chen, Shiang-Fan; Jones, Gareth; Rossiter, Stephen J.

2009-01-01

The origin and maintenance of intraspecific variation in vocal signals is important for population divergence and speciation. Where vocalizations are transmitted by vertical cultural inheritance, similarity will reflect co-ancestry, and thus vocal divergence should reflect genetic structure. Horseshoe bats are characterized by echolocation calls dominated by a constant frequency component that is partly determined by maternal imprinting. Although previous studies showed that constant frequency calls are also influenced by some non-genetic factors, it is not known how frequency relates to genetic structure. To test this, we related constant frequency variation to genetic and non-genetic variables in the Formosan lesser horseshoe bat (Rhinolophus monoceros). Recordings of bats from across Taiwan revealed that females called at higher frequencies than males; however, we found no effect of environmental or morphological factors on call frequency. By comparison, variation showed clear population structure, with frequencies lower in the centre and east, and higher in the north and south. Within these regions, frequency divergence was directional and correlated with geographical distance, suggesting that call frequencies are subject to cultural drift. However, microsatellite clustering analysis showed that broad differences in constant frequency among populations corresponded to discontinuities in allele frequencies resulting from vicariant events. Our results provide evidence that the processes shaping genetic subdivision have concomitant consequences for divergence in echolocation call frequency. PMID:19692399

Neural Processing of Target Distance by Echolocating Bats: Functional Roles of the Auditory Midbrain

PubMed Central

Wenstrup, Jeffrey J.; Portfors, Christine V.

2011-01-01

Using their biological sonar, bats estimate distance to avoid obstacles and capture moving prey. The primary distance cue is the delay between the bat's emitted echolocation pulse and the return of an echo. The mustached bat's auditory midbrain (inferior colliculus, IC) is crucial to the analysis of pulse-echo delay. IC neurons are selective for certain delays between frequency modulated (FM) elements of the pulse and echo. One role of the IC is to create these “delay-tuned”, “FM-FM” response properties through a series of spectro-temporal integrative interactions. A second major role of the midbrain is to project target distance information to many parts of the brain. Pathways through auditory thalamus undergo radical reorganization to create highly ordered maps of pulse-echo delay in auditory cortex, likely contributing to perceptual features of target distance analysis. FM-FM neurons in IC also project strongly to pre-motor centers including the pretectum and the pontine nuclei. These pathways may contribute to rapid adjustments in flight, body position, and sonar vocalizations that occur as a bat closes in on a target. PMID:21238485

Echolocating bats use a nearly time-optimal strategy to intercept prey.

PubMed

Ghose, Kaushik; Horiuchi, Timothy K; Krishnaprasad, P S; Moss, Cynthia F

2006-05-01

Acquisition of food in many animal species depends on the pursuit and capture of moving prey. Among modern humans, the pursuit and interception of moving targets plays a central role in a variety of sports, such as tennis, football, Frisbee, and baseball. Studies of target pursuit in animals, ranging from dragonflies to fish and dogs to humans, have suggested that they all use a constant bearing (CB) strategy to pursue prey or other moving targets. CB is best known as the interception strategy employed by baseball outfielders to catch ballistic fly balls. CB is a time-optimal solution to catch targets moving along a straight line, or in a predictable fashion--such as a ballistic baseball, or a piece of food sinking in water. Many animals, however, have to capture prey that may make evasive and unpredictable maneuvers. Is CB an optimum solution to pursuing erratically moving targets? Do animals faced with such erratic prey also use CB? In this paper, we address these questions by studying prey capture in an insectivorous echolocating bat. Echolocating bats rely on sonar to pursue and capture flying insects. The bat's prey may emerge from foliage for a brief time, fly in erratic three-dimensional paths before returning to cover. Bats typically take less than one second to detect, localize and capture such insects. We used high speed stereo infra-red videography to study the three dimensional flight paths of the big brown bat, Eptesicus fuscus, as it chased erratically moving insects in a dark laboratory flight room. We quantified the bat's complex pursuit trajectories using a simple delay differential equation. Our analysis of the pursuit trajectories suggests that bats use a constant absolute target direction strategy during pursuit. We show mathematically that, unlike CB, this approach minimizes the time it takes for a pursuer to intercept an unpredictably moving target. Interestingly, the bat's behavior is similar to the interception strategy implemented in some guided missiles. We suggest that the time-optimal strategy adopted by the bat is in response to the evolutionary pressures of having to capture erratic and fast moving insects.

Echolocating bats use future-target information for optimal foraging.

PubMed

Fujioka, Emyo; Aihara, Ikkyu; Sumiya, Miwa; Aihara, Kazuyuki; Hiryu, Shizuko

2016-04-26

When seeing or listening to an object, we aim our attention toward it. While capturing prey, many animal species focus their visual or acoustic attention toward the prey. However, for multiple prey items, the direction and timing of attention for effective foraging remain unknown. In this study, we adopted both experimental and mathematical methodology with microphone-array measurements and mathematical modeling analysis to quantify the attention of echolocating bats that were repeatedly capturing airborne insects in the field. Here we show that bats select rational flight paths to consecutively capture multiple prey items. Microphone-array measurements showed that bats direct their sonar attention not only to the immediate prey but also to the next prey. In addition, we found that a bat's attention in terms of its flight also aims toward the next prey even when approaching the immediate prey. Numerical simulations revealed a possibility that bats shift their flight attention to control suitable flight paths for consecutive capture. When a bat only aims its flight attention toward its immediate prey, it rarely succeeds in capturing the next prey. These findings indicate that bats gain increased benefit by distributing their attention among multiple targets and planning the future flight path based on additional information of the next prey. These experimental and mathematical studies allowed us to observe the process of decision making by bats during their natural flight dynamics.

The Genomes of Two Bat Species with Long Constant Frequency Echolocation Calls.

PubMed

Dong, Dong; Lei, Ming; Hua, Panyu; Pan, Yi-Hsuan; Mu, Shuo; Zheng, Guantao; Pang, Erli; Lin, Kui; Zhang, Shuyi

2017-01-01

Bats can perceive the world by using a wide range of sensory systems, and some of the systems have become highly specialized, such as auditory sensory perception. Among bat species, the Old World leaf-nosed bats and horseshoe bats (rhinolophoid bats) possess the most sophisticated echolocation systems. Here, we reported the whole-genome sequencing and de novo assembles of two rhinolophoid bats-the great leaf-nosed bat (Hipposideros armiger) and the Chinese rufous horseshoe bat (Rhinolophus sinicus). Comparative genomic analyses revealed the adaptation of auditory sensory perception in the rhinolophoid bat lineages, probably resulting from the extreme selectivity used in the auditory processing by these bats. Pseudogenization of some vision-related genes in rhinolophoid bats was observed, suggesting that these genes have undergone relaxed natural selection. An extensive contraction of olfactory receptor gene repertoires was observed in the lineage leading to the common ancestor of bats. Further extensive gene contractions can be observed in the branch leading to the rhinolophoid bats. Such concordance suggested that molecular changes at one sensory gene might have direct consequences for genes controlling for other sensory modalities. To characterize the population genetic structure and patterns of evolution, we re-sequenced the genome of 20 great leaf-nosed bats from four different geographical locations of China. The result showed similar sequence diversity values and little differentiation among populations. Moreover, evidence of genetic adaptations to high altitudes in the great leaf-nosed bats was observed. Taken together, our work provided a useful resource for future research on the evolution of bats. © The Author 2016. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Big brown bats (Eptesicus fuscus) reveal diverse strategies for sonar target tracking in clutter.

PubMed

Mao, Beatrice; Aytekin, Murat; Wilkinson, Gerald S; Moss, Cynthia F

2016-09-01

Bats actively adjust the acoustic features of their sonar calls to control echo information specific to a given task and environment. A previous study investigated how bats adapted their echolocation behavior when tracking a moving target in the presence of a stationary distracter at different distances and angular offsets. The use of only one distracter, however, left open the possibility that a bat could reduce the interference of the distracter by turning its head. Here, bats tracked a moving target in the presence of one or two symmetrically placed distracters to investigate adaptive echolocation behavior in a situation where vocalizing off-axis would result in increased interference from distracter echoes. Both bats reduced bandwidth and duration but increased sweep rate in more challenging distracter conditions, and surprisingly, made more head turns in the two-distracter condition compared to one, but only when distracters were placed at large angular offsets. However, for most variables examined, subjects showed distinct strategies to reduce clutter interference, either by (1) changing spectral or temporal features of their calls, or (2) producing large numbers of sonar sound groups and consistent head-turning behavior. The results suggest that individual bats can use different strategies for target tracking in cluttered environments.

Clutter and conspecifics: a comparison of their influence on echolocation and flight behaviour in Daubenton's bat, Myotis daubentonii.

PubMed

Fawcett, Kayleigh; Ratcliffe, John M

2015-03-01

We compared the influence of conspecifics and clutter on echolocation and flight speed in the bat Myotis daubentonii. In a large room, actual pairs of bats exhibited greater disparity in peak frequency (PF), minimum frequency (F MIN) and call period compared to virtual pairs of bats, each flying alone. Greater inter-individual disparity in PF and F MIN may reduce acoustic interference and/or increase signal self-recognition in the presence of conspecifics. Bats flying alone in a smaller flight room, to simulate a more cluttered habitat as compared to the large flight room, produced calls of shorter duration and call period, lower intensity, and flew at lower speeds. In cluttered space, shorter call duration should reduce masking, while shorter call period equals more updates to the bat's auditory scene. Lower intensity likely reflects reduced range detection requirements, reduced speed the demands of flying in clutter. Our results show that some changes (e.g. PF separation) are associated with conspecifics, others with closed habitat (e.g. reduced call intensity). However, we demonstrate that call duration, period, and flight speed appear similarly influenced by conspecifics and clutter. We suggest that some changes reduce conspecific interference and/or improve self-recognition, while others demonstrate that bats experience each other like clutter.

Fine-tuned echolocation and capture-flight of Myotis capaccinii when facing different-sized insect and fish prey.

PubMed

Aizpurua, Ostaizka; Aihartza, Joxerra; Alberdi, Antton; Baagøe, Hans J; Garin, Inazio

2014-09-15

Formerly thought to be a strictly insectivorous trawling bat, recent studies have shown that Myotis capaccinii also preys on fish. To determine whether differences exist in bat flight behaviour, prey handling and echolocation characteristics when catching fish and insects of different size, we conducted a field experiment focused on the last stage of prey capture. We used synchronized video and ultrasound recordings to measure several flight and dip features as well as echolocation characteristics, focusing on terminal buzz phase I, characterized by a call rate exceeding 100 Hz, and buzz phase II, characterized by a drop in the fundamental well below 20 kHz and a repetition rate exceeding 150 Hz. When capturing insects, bats used both parts of the terminal phase to the same extent, and performed short and superficial drags on the water surface. In contrast, when preying on fish, buzz I was longer and buzz II shorter, and the bats made longer and deeper dips. These variations suggest that lengthening buzz I and shortening buzz II when fishing is beneficial, probably because buzz I gives better discrimination ability and the broader sonar beam provided by buzz II is useless when no evasive flight of the prey is expected. Additionally, bats continued emitting calls beyond the theoretical signal-overlap zone, suggesting that they might obtain information even when they have surpassed that threshold, at least initially. This study shows that M. capaccinii can regulate the temporal components of its feeding buzzes and modify prey capture technique according to the target. © 2014. Published by The Company of Biologists Ltd.

Tongue-driven sonar beam steering by a lingual-echolocating fruit bat

PubMed Central

Falk, Benjamin; Chiu, Chen; Krishnan, Anand; Arbour, Jessica H.; Moss, Cynthia F.

2017-01-01

Animals enhance sensory acquisition from a specific direction by movements of head, ears, or eyes. As active sensing animals, echolocating bats also aim their directional sonar beam to selectively “illuminate” a confined volume of space, facilitating efficient information processing by reducing echo interference and clutter. Such sonar beam control is generally achieved by head movements or shape changes of the sound-emitting mouth or nose. However, lingual-echolocating Egyptian fruit bats, Rousettus aegyptiacus, which produce sound by clicking their tongue, can dramatically change beam direction at very short temporal intervals without visible morphological changes. The mechanism supporting this capability has remained a mystery. Here, we measured signals from free-flying Egyptian fruit bats and discovered a systematic angular sweep of beam focus across increasing frequency. This unusual signal structure has not been observed in other animals and cannot be explained by the conventional and widely-used “piston model” that describes the emission pattern of other bat species. Through modeling, we show that the observed beam features can be captured by an array of tongue-driven sound sources located along the side of the mouth, and that the sonar beam direction can be steered parsimoniously by inducing changes to the pattern of phase differences through moving tongue location. The effects are broadly similar to those found in a phased array—an engineering design widely found in human-made sonar systems that enables beam direction changes without changes in the physical transducer assembly. Our study reveals an intriguing parallel between biology and human engineering in solving problems in fundamentally similar ways. PMID:29244805

Tongue-driven sonar beam steering by a lingual-echolocating fruit bat.

PubMed

Lee, Wu-Jung; Falk, Benjamin; Chiu, Chen; Krishnan, Anand; Arbour, Jessica H; Moss, Cynthia F

2017-12-01

Animals enhance sensory acquisition from a specific direction by movements of head, ears, or eyes. As active sensing animals, echolocating bats also aim their directional sonar beam to selectively "illuminate" a confined volume of space, facilitating efficient information processing by reducing echo interference and clutter. Such sonar beam control is generally achieved by head movements or shape changes of the sound-emitting mouth or nose. However, lingual-echolocating Egyptian fruit bats, Rousettus aegyptiacus, which produce sound by clicking their tongue, can dramatically change beam direction at very short temporal intervals without visible morphological changes. The mechanism supporting this capability has remained a mystery. Here, we measured signals from free-flying Egyptian fruit bats and discovered a systematic angular sweep of beam focus across increasing frequency. This unusual signal structure has not been observed in other animals and cannot be explained by the conventional and widely-used "piston model" that describes the emission pattern of other bat species. Through modeling, we show that the observed beam features can be captured by an array of tongue-driven sound sources located along the side of the mouth, and that the sonar beam direction can be steered parsimoniously by inducing changes to the pattern of phase differences through moving tongue location. The effects are broadly similar to those found in a phased array-an engineering design widely found in human-made sonar systems that enables beam direction changes without changes in the physical transducer assembly. Our study reveals an intriguing parallel between biology and human engineering in solving problems in fundamentally similar ways.

No genome-wide protein sequence convergence for echolocation.

PubMed

Zou, Zhengting; Zhang, Jianzhi

2015-05-01

Toothed whales and two groups of bats independently acquired echolocation, the ability to locate and identify objects by reflected sound. Echolocation requires physiologically complex and coordinated vocal, auditory, and neural functions, but the molecular basis of the capacity for echolocation is not well understood. A recent study suggested that convergent amino acid substitutions widespread in the proteins of echolocators underlay the convergent origins of mammalian echolocation. Here, we show that genomic signatures of molecular convergence between echolocating lineages are generally no stronger than those between echolocating and comparable nonecholocating lineages. The same is true for the group of 29 hearing-related proteins claimed to be enriched with molecular convergence. Reexamining the previous selection test reveals several flaws and invalidates the asserted evidence for adaptive convergence. Together, these findings indicate that the reported genomic signatures of convergence largely reflect the background level of sequence convergence unrelated to the origins of echolocation. © The Author 2015. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Forest structure affects trophic linkages: How silvicultural disturbance impacts bats and their insect prey

USGS Publications Warehouse

Dodd, L.E.; Lacki, M.J.; Britzke, E.R.; Buehler, D.A.; Keyser, P.D.; Larkin, J.L.; Rodewald, A.D.; Wigley, T.B.; Wood, P.B.; Rieske, L.K.

2012-01-01

Vertebrate insectivores such as bats are a pervasive top-down force on prey populations in forest ecosystems. Conservation focusing on forest-dwelling bats requires understanding of community-level interactions between these predators and their insect prey. Our study assessed bat activity and insect occurrence (abundance and diversity) across a gradient of forest disturbance and structure (silvicultural treatments) in the Central Appalachian region of North America. We conducted acoustic surveys of bat echolocation concurrent with insect surveys using blacklight and malaise traps over 2 years. Predator activity, prey occurrence and prey biomass varied seasonally and across the region. The number of bat echolocation pulses was positively related with forest disturbance, whereas prey demonstrated varied trends. Lepidopteran abundance was negatively related with disturbance, while dipteran abundance and diversity was positively related with disturbance. Coleoptera were unaffected. Neither bat nor insect response variables differed between plot interiors and edges. Correlations between bat activity and vegetative structure reflected differences in foraging behavior among ensembles. Activity of myotine bats was correlated with variables describing sub-canopy vegetation, whereas activity of lasiurine bats was more closely correlated with canopy-level vegetation. Lepidopteran abundance was correlated with variables describing canopy and sub-canopy vegetation, whereas coleopteran and dipteran occurrence were more closely correlated with canopy-level vegetative structure. Our study demonstrates regional variation in bat activity and prey occurrence across a forested disturbance gradient. Land management and conservation efforts should consider the importance of vegetation structure and plant species richness to sustain forest-dwelling bats and their insect prey.

Single-click beam patterns suggest dynamic changes to the field of view of echolocating Atlantic spotted dolphins (Stenella frontalis) in the wild.

PubMed

Jensen, Frants H; Wahlberg, Magnus; Beedholm, Kristian; Johnson, Mark; de Soto, Natacha Aguilar; Madsen, Peter T

2015-05-01

Echolocating animals exercise an extensive control over the spectral and temporal properties of their biosonar signals to facilitate perception of their actively generated auditory scene when homing in on prey. The intensity and directionality of the biosonar beam defines the field of view of echolocating animals by affecting the acoustic detection range and angular coverage. However, the spatial relationship between an echolocating predator and its prey changes rapidly, resulting in different biosonar requirements throughout prey pursuit and capture. Here, we measured single-click beam patterns using a parametric fit procedure to test whether free-ranging Atlantic spotted dolphins (Stenella frontalis) modify their biosonar beam width. We recorded echolocation clicks using a linear array of receivers and estimated the beam width of individual clicks using a parametric spectral fit, cross-validated with well-established composite beam pattern estimates. The dolphins apparently increased the biosonar beam width, to a large degree without changing the signal frequency, when they approached the recording array. This is comparable to bats that also expand their field of view during prey capture, but achieve this by decreasing biosonar frequency. This behaviour may serve to decrease the risk that rapid escape movements of prey take them outside the biosonar beam of the predator. It is likely that shared sensory requirements have resulted in bats and toothed whales expanding their acoustic field of view at close range to increase the likelihood of successfully acquiring prey using echolocation, representing a case of convergent evolution of echolocation behaviour between these two taxa. © 2015. Published by The Company of Biologists Ltd.

The Acuity of Echolocation: Spatial Resolution in Sighted Persons Compared to the Performance of an Expert Who Is Blind

ERIC Educational Resources Information Center

Teng, Santani; Whitney, David

2011-01-01

Echolocation is a specialized application of spatial hearing that uses reflected auditory information to localize objects and represent the external environment. Although it has been documented extensively in nonhuman species, such as bats and dolphins, its use by some persons who are blind as a navigation and object-identification aid has…

Bats coordinate sonar and flight behavior as they forage in open and cluttered environments.

PubMed

Falk, Benjamin; Jakobsen, Lasse; Surlykke, Annemarie; Moss, Cynthia F

2014-12-15

Echolocating bats use active sensing as they emit sounds and listen to the returning echoes to probe their environment for navigation, obstacle avoidance and pursuit of prey. The sensing behavior of bats includes the planning of 3D spatial trajectory paths, which are guided by echo information. In this study, we examined the relationship between active sonar sampling and flight motor output as bats changed environments from open space to an artificial forest in a laboratory flight room. Using high-speed video and audio recordings, we reconstructed and analyzed 3D flight trajectories, sonar beam aim and acoustic sonar emission patterns as the bats captured prey. We found that big brown bats adjusted their sonar call structure, temporal patterning and flight speed in response to environmental change. The sonar beam aim of the bats predicted the flight turn rate in both the open room and the forest. However, the relationship between sonar beam aim and turn rate changed in the forest during the final stage of prey pursuit, during which the bat made shallower turns. We found flight stereotypy developed over multiple days in the forest, but did not find evidence for a reduction in active sonar sampling with experience. The temporal patterning of sonar sound groups was related to path planning around obstacles in the forest. Together, these results contribute to our understanding of how bats coordinate echolocation and flight behavior to represent and navigate their environment. © 2014. Published by The Company of Biologists Ltd.

Bats coordinate sonar and flight behavior as they forage in open and cluttered environments

PubMed Central

Falk, Benjamin; Jakobsen, Lasse; Surlykke, Annemarie; Moss, Cynthia F.

2014-01-01

Echolocating bats use active sensing as they emit sounds and listen to the returning echoes to probe their environment for navigation, obstacle avoidance and pursuit of prey. The sensing behavior of bats includes the planning of 3D spatial trajectory paths, which are guided by echo information. In this study, we examined the relationship between active sonar sampling and flight motor output as bats changed environments from open space to an artificial forest in a laboratory flight room. Using high-speed video and audio recordings, we reconstructed and analyzed 3D flight trajectories, sonar beam aim and acoustic sonar emission patterns as the bats captured prey. We found that big brown bats adjusted their sonar call structure, temporal patterning and flight speed in response to environmental change. The sonar beam aim of the bats predicted the flight turn rate in both the open room and the forest. However, the relationship between sonar beam aim and turn rate changed in the forest during the final stage of prey pursuit, during which the bat made shallower turns. We found flight stereotypy developed over multiple days in the forest, but did not find evidence for a reduction in active sonar sampling with experience. The temporal patterning of sonar sound groups was related to path planning around obstacles in the forest. Together, these results contribute to our understanding of how bats coordinate echolocation and flight behavior to represent and navigate their environment. PMID:25394632

Active control of acoustic field-of-view in a biosonar system.

PubMed

Yovel, Yossi; Falk, Ben; Moss, Cynthia F; Ulanovsky, Nachum

2011-09-01

Active-sensing systems abound in nature, but little is known about systematic strategies that are used by these systems to scan the environment. Here, we addressed this question by studying echolocating bats, animals that have the ability to point their biosonar beam to a confined region of space. We trained Egyptian fruit bats to land on a target, under conditions of varying levels of environmental complexity, and measured their echolocation and flight behavior. The bats modulated the intensity of their biosonar emissions, and the spatial region they sampled, in a task-dependant manner. We report here that Egyptian fruit bats selectively change the emission intensity and the angle between the beam axes of sequentially emitted clicks, according to the distance to the target, and depending on the level of environmental complexity. In so doing, they effectively adjusted the spatial sector sampled by a pair of clicks-the "field-of-view." We suggest that the exact point within the beam that is directed towards an object (e.g., the beam's peak, maximal slope, etc.) is influenced by three competing task demands: detection, localization, and angular scanning-where the third factor is modulated by field-of-view. Our results suggest that lingual echolocation (based on tongue clicks) is in fact much more sophisticated than previously believed. They also reveal a new parameter under active control in animal sonar-the angle between consecutive beams. Our findings suggest that acoustic scanning of space by mammals is highly flexible and modulated much more selectively than previously recognized.

Navigation: bat orientation using Earth's magnetic field.

PubMed

Holland, Richard A; Thorup, Kasper; Vonhof, Maarten J; Cochran, William W; Wikelski, Martin

2006-12-07

Bats famously orientate at night by echolocation, but this works over only a short range, and little is known about how they navigate over longer distances. Here we show that the homing behaviour of Eptesicus fuscus, known as the big brown bat, can be altered by artificially shifting the Earth's magnetic field, indicating that these bats rely on a magnetic compass to return to their home roost. This finding adds to the impressive array of sensory abilities possessed by this animal for navigation in the dark.

Sensory Ecology of Water Detection by Bats: A Field Experiment

PubMed Central

Russo, Danilo; Cistrone, Luca; Jones, Gareth

2012-01-01

Bats face a great risk of dehydration, so sensory mechanisms for water recognition are crucial for their survival. In the laboratory, bats recognized any smooth horizontal surface as water because these provide analogous reflections of echolocation calls. We tested whether bats also approach smooth horizontal surfaces other than water to drink in nature by partly covering watering troughs used by hundreds of bats with a Perspex layer mimicking water. We aimed 1) to confirm that under natural conditions too bats mistake any horizontal smooth surface for water by testing this on large numbers of individuals from a range of species and 2) to assess the occurrence of learning effects. Eleven bat species mistook Perspex for water relying chiefly on echoacoustic information. Using black instead of transparent Perspex did not deter bats from attempting to drink. In Barbastella barbastellus no echolocation differences occurred between bats approaching the water and the Perspex surfaces respectively, confirming that bats perceive water and Perspex to be acoustically similar. The drinking attempt rates at the fake surface were often lower than those recorded in the laboratory: bats then either left the site or moved to the control water surface. This suggests that bats modified their behaviour as soon as the lack of drinking reward had overridden the influence of echoacoustic information. Regardless of which of two adjoining surfaces was covered, bats preferentially approached and attempted to drink from the first surface encountered, probably because they followed a common route, involving spatial memory and perhaps social coordination. Overall, although acoustic recognition itself is stereotyped and its importance in the drinking process overwhelming, our findings point at the role of experience in increasing behavioural flexibility under natural conditions. PMID:23133558

Effect of echolocation behavior-related constant frequency-frequency modulation sound on the frequency tuning of inferior collicular neurons in Hipposideros armiger.

PubMed

Tang, Jia; Fu, Zi-Ying; Wei, Chen-Xue; Chen, Qi-Cai

2015-08-01

In constant frequency-frequency modulation (CF-FM) bats, the CF-FM echolocation signals include both CF and FM components, yet the role of such complex acoustic signals in frequency resolution by bats remains unknown. Using CF and CF-FM echolocation signals as acoustic stimuli, the responses of inferior collicular (IC) neurons of Hipposideros armiger were obtained by extracellular recordings. We tested the effect of preceding CF or CF-FM sounds on the shape of the frequency tuning curves (FTCs) of IC neurons. Results showed that both CF-FM and CF sounds reduced the number of FTCs with tailed lower-frequency-side of IC neurons. However, more IC neurons experienced such conversion after adding CF-FM sound compared with CF sound. We also found that the Q 20 value of the FTC of IC neurons experienced the largest increase with the addition of CF-FM sound. Moreover, only CF-FM sound could cause an increase in the slope of the neurons' FTCs, and such increase occurred mainly in the lower-frequency edge. These results suggested that CF-FM sound could increase the accuracy of frequency analysis of echo and cut-off low-frequency elements from the habitat of bats more than CF sound.

Bidirectional Echolocation in the Bat Barbastella barbastellus: Different Signals of Low Source Level Are Emitted Upward through the Nose and Downward through the Mouth

PubMed Central

Seibert, Anna-Maria; Koblitz, Jens C.; Denzinger, Annette; Schnitzler, Hans-Ulrich

2015-01-01

The Barbastelle bat (Barbastella barbastellus) preys almost exclusively on tympanate moths. While foraging, this species alternates between two different signal types. We investigated whether these signals differ in emission direction or source level (SL) as assumed from earlier single microphone recordings. We used two different settings of a 16-microphone array to determine SL and sonar beam direction at various locations in the field. Both types of search signals had low SLs (81 and 82 dB SPL rms re 1 m) as compared to other aerial-hawking bats. These two signal types were emitted in different directions; type 1 signals were directed downward and type 2 signals upward. The angle between beam directions was approximately 70°. Barbastelle bats are able to emit signals through both the mouth and the nostrils. As mouth and nostrils are roughly perpendicular to each other, we conclude that type 1 signals are emitted through the mouth while type 2 signals and approach signals are emitted through the nose. We hypothesize that the “stealth” echolocation system of B. barbastellus is bifunctional. The more upward directed nose signals may be mainly used for search and localization of prey. Their low SL prevents an early detection by eared moths but comes at the expense of a strongly reduced detection range for the environment below the bat. The more downward directed mouth signals may have evolved to compensate for this disadvantage and may be mainly used for spatial orientation. We suggest that the possibly bifunctional echolocation system of B. barbastellus has been adapted to the selective foraging of eared moths and is an excellent example of a sophisticated sensory arms race between predator and prey. PMID:26352271

Bidirectional Echolocation in the Bat Barbastella barbastellus: Different Signals of Low Source Level Are Emitted Upward through the Nose and Downward through the Mouth.

PubMed

Seibert, Anna-Maria; Koblitz, Jens C; Denzinger, Annette; Schnitzler, Hans-Ulrich

2015-01-01

The Barbastelle bat (Barbastella barbastellus) preys almost exclusively on tympanate moths. While foraging, this species alternates between two different signal types. We investigated whether these signals differ in emission direction or source level (SL) as assumed from earlier single microphone recordings. We used two different settings of a 16-microphone array to determine SL and sonar beam direction at various locations in the field. Both types of search signals had low SLs (81 and 82 dB SPL rms re 1 m) as compared to other aerial-hawking bats. These two signal types were emitted in different directions; type 1 signals were directed downward and type 2 signals upward. The angle between beam directions was approximately 70°. Barbastelle bats are able to emit signals through both the mouth and the nostrils. As mouth and nostrils are roughly perpendicular to each other, we conclude that type 1 signals are emitted through the mouth while type 2 signals and approach signals are emitted through the nose. We hypothesize that the "stealth" echolocation system of B. barbastellus is bifunctional. The more upward directed nose signals may be mainly used for search and localization of prey. Their low SL prevents an early detection by eared moths but comes at the expense of a strongly reduced detection range for the environment below the bat. The more downward directed mouth signals may have evolved to compensate for this disadvantage and may be mainly used for spatial orientation. We suggest that the possibly bifunctional echolocation system of B. barbastellus has been adapted to the selective foraging of eared moths and is an excellent example of a sophisticated sensory arms race between predator and prey.

The sonar aperture and its neural representation in bats.

PubMed

Heinrich, Melina; Warmbold, Alexander; Hoffmann, Susanne; Firzlaff, Uwe; Wiegrebe, Lutz

2011-10-26

As opposed to visual imaging, biosonar imaging of spatial object properties represents a challenge for the auditory system because its sensory epithelium is not arranged along space axes. For echolocating bats, object width is encoded by the amplitude of its echo (echo intensity) but also by the naturally covarying spread of angles of incidence from which the echoes impinge on the bat's ears (sonar aperture). It is unclear whether bats use the echo intensity and/or the sonar aperture to estimate an object's width. We addressed this question in a combined psychophysical and electrophysiological approach. In three virtual-object playback experiments, bats of the species Phyllostomus discolor had to discriminate simple reflections of their own echolocation calls differing in echo intensity, sonar aperture, or both. Discrimination performance for objects with physically correct covariation of sonar aperture and echo intensity ("object width") did not differ from discrimination performances when only the sonar aperture was varied. Thus, the bats were able to detect changes in object width in the absence of intensity cues. The psychophysical results are reflected in the responses of a population of units in the auditory midbrain and cortex that responded strongest to echoes from objects with a specific sonar aperture, regardless of variations in echo intensity. Neurometric functions obtained from cortical units encoding the sonar aperture are sufficient to explain the behavioral performance of the bats. These current data show that the sonar aperture is a behaviorally relevant and reliably encoded cue for object size in bat sonar.

Development of echolocation and communication vocalizations in the big brown bat, Eptesicus fuscus.

PubMed

Monroy, Jenna A; Carter, Matthew E; Miller, Kimberly E; Covey, Ellen

2011-05-01

Big brown bats form large maternity colonies of up to 200 mothers and their pups. If pups are separated from their mothers, they can locate each other using vocalizations. The goal of this study was to systematically characterize the development of echolocation and communication calls from birth through adulthood to determine whether they develop from a common precursor at the same or different rates, or whether both types are present initially. Three females and their six pups were isolated from our captive breeding colony. We recorded vocal activity from postnatal day 1 to 35, both when the pups were isolated and when they were reunited with their mothers. At birth, pups exclusively emitted isolation calls, with a fundamental frequency range <20 kHz, and duration >30 ms. By the middle of week 1, different types of vocalizations began to emerge. Starting in week 2, pups in the presence of their mothers emitted sounds that resembled adult communication vocalizations, with a lower frequency range and longer durations than isolation calls or echolocation signals. During weeks 2 and 3, these vocalizations were extremely heterogeneous, suggesting that the pups went through a babbling stage before establishing a repertoire of stereotyped adult vocalizations around week 4. By week 4, vocalizations emitted when pups were alone were identical to adult echolocation signals. Echolocation and communication signals both appear to develop from the isolation call, diverging during week 2 and continuing to develop at different rates for several weeks until the adult vocal repertoire is established.

Tempo and mode of antibat ultrasound production and sonar jamming in the diverse hawkmoth radiation.

PubMed

Kawahara, Akito Y; Barber, Jesse R

2015-05-19

The bat-moth arms race has existed for over 60 million y, with moths evolving ultrasonically sensitive ears and ultrasound-producing organs to combat bat predation. The evolution of these defenses has never been thoroughly examined because of limitations in simultaneously conducting behavioral and phylogenetic analyses across an entire group. Hawkmoths include >1,500 species worldwide, some of which produce ultrasound using genital stridulatory structures. However, the function and evolution of this behavior remain largely unknown. We built a comprehensive behavioral dataset of hawkmoth hearing and ultrasonic reply to sonar attack using high-throughput field assays. Nearly half of the species tested (57 of 124 species) produced ultrasound to tactile stimulation or playback of bat echolocation attack. To test the function of ultrasound, we pitted big brown bats (Eptesicus fuscus) against hawkmoths over multiple nights and show that hawkmoths jam bat sonar. Ultrasound production was immediately and consistently effective at thwarting attack and bats regularly performed catching behavior without capturing moths. We also constructed a fossil-calibrated, multigene phylogeny to study the evolutionary history and divergence times of these antibat strategies across the entire family. We show that ultrasound production arose in multiple groups, starting in the late Oligocene (∼ 26 Ma) after the emergence of insectivorous bats. Sonar jamming and bat-detecting ears arose twice, independently, in the Miocene (18-14 Ma) either from earless hawkmoths that produced ultrasound in response to physical contact only, or from species that did not respond to touch or bat echolocation attack.

Migratory bats respond to artificial green light with positive phototaxis.

PubMed

Voigt, Christian C; Roeleke, Manuel; Marggraf, Lara; Pētersons, Gunārs; Voigt-Heucke, Silke L

2017-01-01

Artificial light at night is spreading worldwide at unprecedented rates, exposing strictly nocturnal animals such as bats to a novel anthropogenic stressor. Previous studies about the effect of artificial light on bats focused almost exclusively on non-migratory species, yet migratory animals such as birds are known to be largely affected by light pollution. Thus, we conducted a field experiment to evaluate if bat migration is affected by artificial light at night. In late summer, we presented artificial green light of 520 nm wavelength to bats that were migrating south along the shoreline of the Baltic Sea. Using a light on-off treatment, we observed that the activity of Pipistrellus nathusii and P. pygmaeus, the two most abundant migratory species at our site, increased by more than 50% in the light-on compared to the light-off treatment. We observed an increased number of feeding buzzes during the light-on compared to the light-off treatment for P. nathusii. However, feeding activity was low in general and did not increase disproportionately during the light-on treatment in relation to the overall echolocation call activity of bats. Further, P. nathusii were attracted towards the green light at a distance of about 23 m, which is way beyond the echolocation detection range for insects of Nathusius' bats. We therefore infer that migratory bats were not attracted to artificial green light because of high insect densities, but instead by positive phototaxis. We conclude that artificial light at night may potentially impact bat migration in a yet unrecognized way.

Active Control of Acoustic Field-of-View in a Biosonar System

PubMed Central

Yovel, Yossi; Falk, Ben; Moss, Cynthia F.; Ulanovsky, Nachum

2011-01-01

Active-sensing systems abound in nature, but little is known about systematic strategies that are used by these systems to scan the environment. Here, we addressed this question by studying echolocating bats, animals that have the ability to point their biosonar beam to a confined region of space. We trained Egyptian fruit bats to land on a target, under conditions of varying levels of environmental complexity, and measured their echolocation and flight behavior. The bats modulated the intensity of their biosonar emissions, and the spatial region they sampled, in a task-dependant manner. We report here that Egyptian fruit bats selectively change the emission intensity and the angle between the beam axes of sequentially emitted clicks, according to the distance to the target, and depending on the level of environmental complexity. In so doing, they effectively adjusted the spatial sector sampled by a pair of clicks—the “field-of-view.” We suggest that the exact point within the beam that is directed towards an object (e.g., the beam's peak, maximal slope, etc.) is influenced by three competing task demands: detection, localization, and angular scanning—where the third factor is modulated by field-of-view. Our results suggest that lingual echolocation (based on tongue clicks) is in fact much more sophisticated than previously believed. They also reveal a new parameter under active control in animal sonar—the angle between consecutive beams. Our findings suggest that acoustic scanning of space by mammals is highly flexible and modulated much more selectively than previously recognized. PMID:21931535

Dynamic representation of 3D auditory space in the midbrain of the free-flying echolocating bat

PubMed Central

2018-01-01

Essential to spatial orientation in the natural environment is a dynamic representation of direction and distance to objects. Despite the importance of 3D spatial localization to parse objects in the environment and to guide movement, most neurophysiological investigations of sensory mapping have been limited to studies of restrained subjects, tested with 2D, artificial stimuli. Here, we show for the first time that sensory neurons in the midbrain superior colliculus (SC) of the free-flying echolocating bat encode 3D egocentric space, and that the bat’s inspection of objects in the physical environment sharpens tuning of single neurons, and shifts peak responses to represent closer distances. These findings emerged from wireless neural recordings in free-flying bats, in combination with an echo model that computes the animal’s instantaneous stimulus space. Our research reveals dynamic 3D space coding in a freely moving mammal engaged in a real-world navigation task. PMID:29633711

Range-dependent flexibility in the acoustic field of view of echolocating porpoises (Phocoena phocoena)

PubMed Central

Wisniewska, Danuta M; Ratcliffe, John M; Beedholm, Kristian; Christensen, Christian B; Johnson, Mark; Koblitz, Jens C; Wahlberg, Magnus; Madsen, Peter T

2015-01-01

Toothed whales use sonar to detect, locate, and track prey. They adjust emitted sound intensity, auditory sensitivity and click rate to target range, and terminate prey pursuits with high-repetition-rate, low-intensity buzzes. However, their narrow acoustic field of view (FOV) is considered stable throughout target approach, which could facilitate prey escape at close-range. Here, we show that, like some bats, harbour porpoises can broaden their biosonar beam during the terminal phase of attack but, unlike bats, maintain the ability to change beamwidth within this phase. Based on video, MRI, and acoustic-tag recordings, we propose this flexibility is modulated by the melon and implemented to accommodate dynamic spatial relationships with prey and acoustic complexity of surroundings. Despite independent evolution and different means of sound generation and transmission, whales and bats adaptively change their FOV, suggesting that beamwidth flexibility has been an important driver in the evolution of echolocation for prey tracking. DOI: http://dx.doi.org/10.7554/eLife.05651.001 PMID:25793440

Range-dependent flexibility in the acoustic field of view of echolocating porpoises (Phocoena phocoena).

PubMed

Wisniewska, Danuta M; Ratcliffe, John M; Beedholm, Kristian; Christensen, Christian B; Johnson, Mark; Koblitz, Jens C; Wahlberg, Magnus; Madsen, Peter T

2015-03-20

Toothed whales use sonar to detect, locate, and track prey. They adjust emitted sound intensity, auditory sensitivity and click rate to target range, and terminate prey pursuits with high-repetition-rate, low-intensity buzzes. However, their narrow acoustic field of view (FOV) is considered stable throughout target approach, which could facilitate prey escape at close-range. Here, we show that, like some bats, harbour porpoises can broaden their biosonar beam during the terminal phase of attack but, unlike bats, maintain the ability to change beamwidth within this phase. Based on video, MRI, and acoustic-tag recordings, we propose this flexibility is modulated by the melon and implemented to accommodate dynamic spatial relationships with prey and acoustic complexity of surroundings. Despite independent evolution and different means of sound generation and transmission, whales and bats adaptively change their FOV, suggesting that beamwidth flexibility has been an important driver in the evolution of echolocation for prey tracking.

Can the elongated hindwing tails of fluttering moths serve as false sonar targets to divert bat attacks?

PubMed

Lee, Wu-Jung; Moss, Cynthia F

2016-05-01

It has long been postulated that the elongated hindwing tails of many saturniid moths have evolved to create false sonar targets to divert the attack of echolocation-guided bat predators. However, rigorous echo-acoustic evidence to support this hypothesis has been lacking. In this study, fluttering luna moths (Actias luna), a species with elongated hindwing tails, were ensonified with frequency modulated chirp signals from all angles of orientation and across the wingbeat cycle. High-speed stereo videography was combined with pulse compression sonar processing to characterize the echo information available to foraging bats. Contrary to previous suggestions, the results show that the tail echoes are weak and do not dominate the sonar returns, compared to the large, planar wings and the moth body. However, the distinctive twisted morphology of the tails create persistent echoes across all angles of orientation, which may induce erroneous sonar target localization and disrupt accurate tracking by echolocating bats. These findings thus suggest a refinement of the false target hypothesis to emphasize sonar localization errors induced by the twisted tails, and highlight the importance of physics-based approaches to study the sensory information involved in the evolutionary arms race between moths and their bat predators.

Acoustic surveys of Hawaiian Hoary Bats in Kahikinui Forest Reserve and Nakula Natural Area Reserve on the Island of Maui

USGS Publications Warehouse

Todd, Christopher M.; Pinzari, Corinna A.; Bonaccorso, Frank

2016-01-01

The Kahikinui Forest Reserve and the adjoining Nakula Natural Area Reserve (KFR-NNAR) was established in 2011 as a conservation area on the leeward slope of Haleakalā Volcano on the island of Maui to protect unique natural features and endangered species including the Hawaiian hoary bat, Lasiurus cinereus semotus. We recorded bat vocalizations from July 2012 to November 2014 using automated echolocation detectors at 14 point locations in the KFRNNAR. Our study area included remnants of recovering mesic montane forest with interspersed grasses (1,250‒1,850 m elevation, hereafter called “forest”) and xeric subalpine shrubland plant communities (1,860‒2,800 m, hereafter called “shrubland”). Monthly detections of Hawaiian hoary bats, Lasiurus cinereus semotus, within the KFR-NNAR identified areas of high and low detection probability as well as foraging activity. Sixty per cent of all detector-nights had confirmed bat vocalizations and included detections in every month of the study. Monthly detection probability values were highest from July to November 2012; these values were significantly greater than values measured in any month thereafter. Pooled values of detection probabilities, mean pulses/night, percentage of nights with feeding activity, and acoustic detections all were greater in the recovering forest zone than corresponding values from the shrublands. Our data provide baseline levels of hoary bat echolocation activity that may be compared with future studies in the KFR-NNAR relative to success criteria for Hawaiian hoary bat habitat restoration.

Spike Train Similarity Space (SSIMS) Method Detects Effects of Obstacle Proximity and Experience on Temporal Patterning of Bat Biosonar

PubMed Central

Accomando, Alyssa W.; Vargas-Irwin, Carlos E.; Simmons, James A.

2018-01-01

Bats emit biosonar pulses in complex temporal patterns that change to accommodate dynamic surroundings. Efforts to quantify these patterns have included analyses of inter-pulse intervals, sonar sound groups, and changes in individual signal parameters such as duration or frequency. Here, the similarity in temporal structure between trains of biosonar pulses is assessed. The spike train similarity space (SSIMS) algorithm, originally designed for neural activity pattern analysis, was applied to determine which features of the environment influence temporal patterning of pulses emitted by flying big brown bats, Eptesicus fuscus. In these laboratory experiments, bats flew down a flight corridor through an obstacle array. The corridor varied in width (100, 70, or 40 cm) and shape (straight or curved). Using a relational point-process framework, SSIMS was able to discriminate between echolocation call sequences recorded from flights in each of the corridor widths. SSIMS was also able to tell the difference between pulse trains recorded during flights where corridor shape through the obstacle array matched the previous trials (fixed, or expected) as opposed to those recorded from flights with randomized corridor shape (variable, or unexpected), but only for the flight path shape in which the bats had previous training. The results show that experience influences the temporal patterns with which bats emit their echolocation calls. It is demonstrated that obstacle proximity to the bat affects call patterns more dramatically than flight path shape. PMID:29472848

Spike Train Similarity Space (SSIMS) Method Detects Effects of Obstacle Proximity and Experience on Temporal Patterning of Bat Biosonar.

PubMed

Accomando, Alyssa W; Vargas-Irwin, Carlos E; Simmons, James A

2018-01-01

Bats emit biosonar pulses in complex temporal patterns that change to accommodate dynamic surroundings. Efforts to quantify these patterns have included analyses of inter-pulse intervals, sonar sound groups, and changes in individual signal parameters such as duration or frequency. Here, the similarity in temporal structure between trains of biosonar pulses is assessed. The spike train similarity space (SSIMS) algorithm, originally designed for neural activity pattern analysis, was applied to determine which features of the environment influence temporal patterning of pulses emitted by flying big brown bats, Eptesicus fuscus . In these laboratory experiments, bats flew down a flight corridor through an obstacle array. The corridor varied in width (100, 70, or 40 cm) and shape (straight or curved). Using a relational point-process framework, SSIMS was able to discriminate between echolocation call sequences recorded from flights in each of the corridor widths. SSIMS was also able to tell the difference between pulse trains recorded during flights where corridor shape through the obstacle array matched the previous trials (fixed, or expected) as opposed to those recorded from flights with randomized corridor shape (variable, or unexpected), but only for the flight path shape in which the bats had previous training. The results show that experience influences the temporal patterns with which bats emit their echolocation calls. It is demonstrated that obstacle proximity to the bat affects call patterns more dramatically than flight path shape.

Object localization using a biosonar beam: how opening your mouth improves localization.

PubMed

Arditi, G; Weiss, A J; Yovel, Y

2015-08-01

Determining the location of a sound source is crucial for survival. Both predators and prey usually produce sound while moving, revealing valuable information about their presence and location. Animals have thus evolved morphological and neural adaptations allowing precise sound localization. Mammals rely on the temporal and amplitude differences between the sound signals arriving at their two ears, as well as on the spectral cues available in the signal arriving at a single ear to localize a sound source. Most mammals rely on passive hearing and are thus limited by the acoustic characteristics of the emitted sound. Echolocating bats emit sound to perceive their environment. They can, therefore, affect the frequency spectrum of the echoes they must localize. The biosonar sound beam of a bat is directional, spreading different frequencies into different directions. Here, we analyse mathematically the spatial information that is provided by the beam and could be used to improve sound localization. We hypothesize how bats could improve sound localization by altering their echolocation signal design or by increasing their mouth gape (the size of the sound emitter) as they, indeed, do in nature. Finally, we also reveal a trade-off according to which increasing the echolocation signal's frequency improves the accuracy of sound localization but might result in undesired large localization errors under low signal-to-noise ratio conditions.

Object localization using a biosonar beam: how opening your mouth improves localization

PubMed Central

Arditi, G.; Weiss, A. J.; Yovel, Y.

2015-01-01

Determining the location of a sound source is crucial for survival. Both predators and prey usually produce sound while moving, revealing valuable information about their presence and location. Animals have thus evolved morphological and neural adaptations allowing precise sound localization. Mammals rely on the temporal and amplitude differences between the sound signals arriving at their two ears, as well as on the spectral cues available in the signal arriving at a single ear to localize a sound source. Most mammals rely on passive hearing and are thus limited by the acoustic characteristics of the emitted sound. Echolocating bats emit sound to perceive their environment. They can, therefore, affect the frequency spectrum of the echoes they must localize. The biosonar sound beam of a bat is directional, spreading different frequencies into different directions. Here, we analyse mathematically the spatial information that is provided by the beam and could be used to improve sound localization. We hypothesize how bats could improve sound localization by altering their echolocation signal design or by increasing their mouth gape (the size of the sound emitter) as they, indeed, do in nature. Finally, we also reveal a trade-off according to which increasing the echolocation signal's frequency improves the accuracy of sound localization but might result in undesired large localization errors under low signal-to-noise ratio conditions. PMID:26361552

Echolocation behaviour of the big brown bat (Eptesicus fuscus) in an obstacle avoidance task of increasing difficulty.

PubMed

Sändig, Sonja; Schnitzler, Hans-Ulrich; Denzinger, Annette

2014-08-15

Four big brown bats (Eptesicus fuscus) were challenged in an obstacle avoidance experiment to localize vertically stretched wires requiring progressively greater accuracy by diminishing the wire-to-wire distance from 50 to 10 cm. The performance of the bats decreased with decreasing gap size. The avoidance task became very difficult below a wire separation of 30 cm, which corresponds to the average wingspan of E. fuscus. Two of the bats were able to pass without collisions down to a gap size of 10 cm in some of the flights. The other two bats only managed to master gap sizes down to 20 and 30 cm, respectively. They also performed distinctly worse at all other gap sizes. With increasing difficulty of the task, the bats changed their flight and echolocation behaviour. Especially at gap sizes of 30 cm and below, flight paths increased in height and flight speed was reduced. In addition, the bats emitted approach signals that were arranged in groups. At all gap sizes, the largest numbers of pulses per group were observed in the last group before passing the obstacle. The more difficult the obstacle avoidance task, the more pulses there were in the groups and the shorter the within-group pulse intervals. In comparable situations, the better-performing bats always emitted groups with more pulses than the less well-performing individuals. We hypothesize that the accuracy of target localization increases with the number of pulses per group and that each group is processed as a package. © 2014. Published by The Company of Biologists Ltd.

Dynamic behavioral strategies during sonar signal emission in roundleaf bats.

PubMed

Feng, Lin; Li, Yitan; Lu, Hongwang

2013-10-02

For echolocating bats which emit biosonar pulses nasally, their nostrils are surrounded by fleshy appendages that diffract the outgoing ultrasonic waves. The posterior leaf, as a prominent part of the noseleaf, was mentioned in previous preliminary observations to move during flight in some species of bats, yet the detailed motion patterns and thus the possible functional role of the posterior leaf movement in biosonar systems remain unclear. In the current work, the motion of the posterior leaf of living pratt's roundleaf bats has been investigated quantitatively. Temporal characterizations of the noseleaf movement and the ultrasonic pulse emission were performed by virtue of synchronized laser vibrometry and sound recording. The results showed that the posterior leaf tilted forwards and restored to original position within tens of milliseconds. Noseleaf motions were temporally correlated with the emitted ultrasonic pulses. The surfaces of the posterior leaf were moving in the anterior direction in most of the pulse duration. The bats were able to switch the motions on or off. From the comparison with the previously reported noseleaf dynamics in horseshoe bat, we find similar ratio sizes and displacements of the noseleaves compared to the used wavelengths, implying that similar behavioral strategies are utilized by species of bats and it may be applied to different components of the signal emitting apparatus. It suggests that the dynamic sensing principles may widely play a role in the biosonar systems and the investigation on time-variant mechanisms is of capital importance to understand the biosonar sensing strategies used by echolocating bats. © 2013.

Bat predation on nocturnally migrating birds

PubMed Central

Ibáñez, Carlos; Juste, Javier; García-Mudarra, Juan L.; Agirre-Mendi, Pablo T.

2001-01-01

Bat predation on birds is a very rare phenomenon in nature. Most documented reports of bird-eating bats refer to tropical bats that occasionally capture resting birds. Millions of small birds concentrate and cross over the world's temperate regions during migration, mainly at night, but no nocturnal predators are known to benefit from this enormous food resource. An analysis of 14,000 fecal pellets of the greater noctule bat (Nyctalus lasiopterus) reveals that this species captures and eats large numbers of migrating passerines, making it the only bat species so far known that regularly preys on birds. The echolocation characteristics and wing morphology of this species strongly suggest that it captures birds in flight. PMID:11493689

Morphology-Induced Information Transfer in Bat Sonar

NASA Astrophysics Data System (ADS)

Reijniers, Jonas; Vanderelst, Dieter; Peremans, Herbert

2010-10-01

It has been argued that an important part of understanding bat echolocation comes down to understanding the morphology of the bat sound processing apparatus. In this Letter we present a method based on information theory that allows us to assess target localization performance of bat sonar, without a priori knowledge on the position, size, or shape of the reflecting target. We demonstrate this method using simulated directivity patterns of the frequency-modulated bat Micronycteris microtis. The results of this analysis indicate that the morphology of this bat’s sound processing apparatus has evolved to be a compromise between sensitivity and accuracy with the pinnae and the noseleaf playing different roles.

Trawling bats exploit an echo-acoustic ground effect

PubMed Central

Zsebok, Sandor; Kroll, Ferdinand; Heinrich, Melina; Genzel, Daria; Siemers, Björn M.; Wiegrebe, Lutz

2013-01-01

A water surface acts not only as an optic mirror but also as an acoustic mirror. Echolocation calls emitted by bats at low heights above water are reflected away from the bat, and hence the background clutter is reduced. Moreover, targets on the surface create an enhanced echo. Here, we formally quantified the effect of the surface and target height on both target detection and -discrimination in a combined laboratory and field approach with Myotis daubentonii. In a two-alternative, forced-choice paradigm, the bats had to detect a mealworm and discriminate it from an inedible dummy (20 mm PVC disc). Psychophysical performance was measured as a function of height above either smooth surfaces (water or PVC) or above a clutter surface (artificial grass). At low heights above the clutter surface (10, 20, or 35 cm), the bats' detection performance was worse than above a smooth surface. At a height of 50 cm, the surface structure had no influence on target detection. Above the clutter surface, also target discrimination was significantly impaired with decreasing target height. A detailed analysis of the bats' echolocation calls during target approach shows that above the clutter surface, the bats produce calls with significantly higher peak frequency. Flight-path reconstruction revealed that the bats attacked an target from below over water but from above over a clutter surface. These results are consistent with the hypothesis that trawling bats exploit an echo-acoustic ground effect, in terms of a spatio-temporal integration of direct reflections with indirect reflections from the water surface, to optimize prey detection and -discrimination not only for prey on the water but also for some range above. PMID:23576990

Middle ear muscle contractions and their relation to pulse and echo evoked potentials in the bat

NASA Technical Reports Server (NTRS)

Henson, O. W., Jr.; Henson, M. M.

1972-01-01

An analysis is made of pulse and echo orientation cries of the Mustache Bat. That bat's cries are characterized by a long, 60 to 30 msec, pure tone component and brief beginning and terminal FM sweeps. In addition to obvious echo overlap and middle ear muscle contractions, the following are examined: (1) characteristics of pulse- and echo-evoked potential under various conditions, (2) evidence of changes in hearing sensitivity during and after pulse emission, and (3) the role of the middle ear muscles in bringing about these changes.

Energy spectrum analysis - A model of echolocation processing. [in animals

NASA Technical Reports Server (NTRS)

Johnson, R. A.; Titlebaum, E. L.

1976-01-01

The paper proposes a frequency domain approach based on energy spectrum analysis of the combination of a signal and its echoes as the processing mechanism for the echolocation process used by bats and other animals. The mechanism is a generalized wide-band one and can account for the large diversity of wide-band signals used for orientation. The coherency in the spectrum of the signal-echo combination is shown to be equivalent to correlation.

Acoustic Scattering of Broadband Echolocation Signals from Prey of Blainville’s Beaked Whales: Modeling and Analysis

DTIC Science & Technology

2006-09-01

biosonar , summarized in the following paragraphs, provides context for this study. 1.1.1 Echolocation in bats Researchers have debated for over two...centuries the capabilities of certain species of animals to use biosonar in orientation, communication, and prey capture. As early as 1793 Italian...marine organisms In complement to the research on the biosonar systems of these capable predators, a concurrent body of research has been conducted on

Mosquito Consumption by Insectivorous Bats: Does Size Matter?

PubMed Central

Gonsalves, Leroy; Bicknell, Brian; Law, Brad; Webb, Cameron; Monamy, Vaughan

2013-01-01

Insectivorous bats have often been touted as biological control for mosquito populations. However, mosquitoes generally represent only a small proportion of bat diet. Given the small size of mosquitoes, restrictions imposed on prey detectability by low frequency echolocation, and variable field metabolic rates (FMR), mosquitoes may not be available to or profitable for all bats. This study investigated whether consumption of mosquitoes was influenced by bat size, which is negatively correlated with echolocation frequency but positively correlated with bat FMR. To assess this, we investigated diets of five eastern Australian bat species (Vespadelus vulturnus Thomas, V. pumilus Gray, Miniopterus australis Tomes, Nyctophilus gouldi Tomes and Chalinolobus gouldii Gray) ranging in size from 4-14 g in coastal forest, using molecular analysis of fecal DNA. Abundances of potential mosquito and non-mosquito prey were concurrently measured to provide data on relative prey abundance. Aedes vigilax was locally the most abundant mosquito species, while Lepidoptera the most abundant insect order. A diverse range of prey was detected in bat feces, although members of Lepidoptera dominated, reflecting relative abundance at trap sites. Consumption of mosquitoes was restricted to V. vulturnus and V. pumilus, two smaller sized bats (4 and 4.5 g). Although mosquitoes were not commonly detected in feces of V. pumilus, they were present in feces of 55 % of V. vulturnus individuals. To meet nightly FMR requirements, Vespadelus spp. would need to consume ~600-660 mosquitoes on a mosquito-only diet, or ~160-180 similar sized moths on a moth-only diet. Lower relative profitability of mosquitoes may provide an explanation for the low level of mosquito consumption among these bats and the absence of mosquitoes in feces of larger bats. Smaller sized bats, especially V. vulturnus, are likely to be those most sensitive to reductions in mosquito abundance and should be monitored during mosquito control activities. PMID:24130851

Biosonar navigation above water I: estimating flight height.

PubMed

Hoffmann, Susanne; Genzel, Daria; Prosch, Selina; Baier, Leonie; Weser, Sabrina; Wiegrebe, Lutz; Firzlaff, Uwe

2015-02-15

Locomotion and foraging on the wing require precise navigation in more than just the horizontal plane. Navigation in three dimensions and, specifically, precise adjustment of flight height are essential for flying animals. Echolocating bats drink from water surfaces in flight, which requires an exceptionally precise vertical navigation. Here, we exploit this behavior in the bat, Phyllostomus discolor, to understand the biophysical and neural mechanisms that allow for sonar-guided navigation in the vertical plane. In a set of behavioral experiments, we show that for echolocating bats, adjustment of flight height depends on the tragus in their outer ears. Specifically, the tragus imposes elevation-specific spectral interference patterns on the echoes of the bats' sonar emissions. Head-related transfer functions of our bats show that these interference patterns are most conspicuous in the frequency range ∼55 kHz. This conspicuousness is faithfully preserved in the frequency tuning and spatial receptive fields of cortical single and multiunits recorded from anesthetized animals. In addition, we recorded vertical spatiotemporal response maps that describe neural tuning in elevation over time. One class of units that were very sharply tuned to frequencies ∼55 kHz showed unusual spatiotemporal response characteristics with a preference for paired echoes where especially the first echo originates from very low elevations. These behavioral and neural data provide the first insight into biosonar-based processing and perception of acoustic elevation cues that are essential for bats to navigate in three-dimensional space. Copyright © 2015 the American Physiological Society.

Steering by hearing: a bat's acoustic gaze is linked to its flight motor output by a delayed, adaptive linear law.

PubMed

Ghose, Kaushik; Moss, Cynthia F

2006-02-08

Adaptive behaviors require sensorimotor computations that convert information represented initially in sensory coordinates to commands for action in motor coordinates. Fundamental to these computations is the relationship between the region of the environment sensed by the animal (gaze) and the animal's locomotor plan. Studies of visually guided animals have revealed an anticipatory relationship between gaze direction and the locomotor plan during target-directed locomotion. Here, we study an acoustically guided animal, an echolocating bat, and relate acoustic gaze (direction of the sonar beam) to flight planning as the bat searches for and intercepts insect prey. We show differences in the relationship between gaze and locomotion as the bat progresses through different phases of insect pursuit. We define acoustic gaze angle, theta(gaze), to be the angle between the sonar beam axis and the bat's flight path. We show that there is a strong linear linkage between acoustic gaze angle at time t [theta(gaze)(t)] and flight turn rate at time t + tau into the future [theta(flight) (t + tau)], which can be expressed by the formula theta(flight) (t + tau) = ktheta(gaze)(t). The gain, k, of this linkage depends on the bat's behavioral state, which is indexed by its sonar pulse rate. For high pulse rates, associated with insect attacking behavior, k is twice as high compared with low pulse rates, associated with searching behavior. We suggest that this adjustable linkage between acoustic gaze and motor output in a flying echolocating bat simplifies the transformation of auditory information to flight motor commands.

Mechanisms underlying intensity-dependent changes in cortical selectivity for frequency-modulated sweeps.

PubMed

Razak, K A

2012-04-01

Frequency-modulated (FM) sweeps are common components of species-specific vocalizations. The intensity of FM sweeps can cover a wide range in the natural environment, but whether intensity affects neural selectivity for FM sweeps is unclear. Bats, such as the pallid bat, which use FM sweeps for echolocation, are suited to address this issue, because the intensity of echoes will vary with target distance. In this study, FM sweep rate selectivity of pallid bat auditory cortex neurons was measured using downward sweeps at different intensities. Neurons became more selective for FM sweep rates present in the bat's echolocation calls as intensity increased. Increased selectivity resulted from stronger inhibition of responses to slower sweep rates. The timing and bandwidth of inhibition generated by frequencies on the high side of the excitatory tuning curve [sideband high-frequency inhibition (HFI)] shape rate selectivity in cortical neurons in the pallid bat. To determine whether intensity-dependent changes in FM rate selectivity were due to altered inhibition, the timing and bandwidth of HFI were quantified at multiple intensities using the two-tone inhibition paradigm. HFI arrived faster relative to excitation as sound intensity increased. The bandwidth of HFI also increased with intensity. The changes in HFI predicted intensity-dependent changes in FM rate selectivity. These data suggest that neural selectivity for a sweep parameter is not static but shifts with intensity due to changes in properties of sideband inhibition.

Dynamics of hippocampal spatial representation in echolocating bats

PubMed Central

Ulanovsky, Nachum; Moss, Cynthia F.

2009-01-01

The ‘place fields‘ of hippocampal pyramidal neurons are not static. For example, upon a contextual change in the environment, place-fields may ‘remap‘ within typical timescales of ~1 minute. A few studies have shown more rapid dynamics in hippocampal activity, linked to internal processes, such as switches between spatial reference frames or changes within the theta cycle. However, little is known about rapid hippocampal place-field dynamics in response to external, sensory stimuli. Here, we studied this question in big brown bats, echolocating mammals in which we can readily measure rapid changes in sensory dynamics (sonar signals), as well as rapid behavioral switches between distal and proximal exploratory modes. First, we show that place-field size was modulated by the availability of sensory information, on a timescale of ~300-milliseconds: Bat hippocampal place-fields were smallest immediately after an echolocation call, but place-fields ‘diffused’ with the passage of time after the call, when echo information was no longer arriving. Second, we show rapid modulation of hippocampal place-fields as the animal switched between two exploratory modes. Third, we compared place fields and spatial-view fields of individual neurons and found that place tuning was much more pronounced than spatial-view tuning. In addition, dynamic fluctuations in spatial-view tuning were stronger than fluctuations in place tuning. Taken together, these results suggest that spatial representation in mammalian hippocampus can be very rapidly modulated by external sensory and behavioral events. PMID:20014379

Localization and tracking of moving objects in two-dimensional space by echolocation.

PubMed

Matsuo, Ikuo

2013-02-01

Bats use frequency-modulated echolocation to identify and capture moving objects in real three-dimensional space. Experimental evidence indicates that bats are capable of locating static objects with a range accuracy of less than 1 μs. A previously introduced model estimates ranges of multiple, static objects using linear frequency modulation (LFM) sound and Gaussian chirplets with a carrier frequency compatible with bat emission sweep rates. The delay time for a single object was estimated with an accuracy of about 1.3 μs by measuring the echo at a low signal-to-noise ratio (SNR). The range accuracy was dependent not only on the SNR but also the Doppler shift, which was dependent on the movements. However, it was unclear whether this model could estimate the moving object range at each timepoint. In this study, echoes were measured from the rotating pole at two receiving points by intermittently emitting LFM sounds. The model was shown to localize moving objects in two-dimensional space by accurately estimating the object's range at each timepoint.

Bat activity in harvested and intact forest stands in the allegheny mountains

USGS Publications Warehouse

Owen, S.F.; Menzel, M.A.; Edwards, J.W.; Ford, W.M.; Menzel, J.M.; Chapman, B.R.; Wood, P.B.; Miller, K.V.

2004-01-01

We used Anabat acoustical monitoring devices to examine bat activity in intact canopy forests, complex canopy forests with gaps, forests subjected to diameter-limit harvests, recent deferment harvests, clearcuts and unmanaged forested riparian areas in the Allegheny Mountains of West Virginia in the summer of 1999. We detected eight species of bats, including the endangered Indiana bat (Myotis sodalis). Most bat activity was concentrated in forested riparian areas. Among upland habitats, activity of silver-haired bats (Lasionycteris noctivagans) and hoary bats (Lasiurus cinereus) was higher in open, less cluttered vegetative types such as recent deferment harvests and clearcuts. Our results suggest that bat species in the central Appalachians partially segregate themselves among vegetative conditions based on differences in body morphology and echolocation call characteristics. From the standpoint of conserving bat foraging habitat for the maximum number of species in the central Appalachians, special emphasis should be placed on protecting forested riparian areas.

Comments on "Killer whale (Orcinus orca) behavioral audiograms" [J. Acoust. Soc. Am. 141, 2387-2398 (2017)].

PubMed

Heffner, Henry E; Heffner, Rickye S

2018-01-01

Branstetter and his colleagues present the audiograms of eight killer whales and provide a comprehensive review of previous killer whale audiograms. In their paper, they say that the present authors have reported a relationship between size and high-frequency hearing but that echolocating cetaceans might be a special case. The purpose of these comments is to clarify that the relationship of a species' high-frequency hearing is not to its size (mass) but to its "functional interaural distance" (a measure of the availability of sound-localization cues). Moreover, it has previously been noted that echolocating animals, cetaceans as well as bats, have extended their high-frequency hearing somewhat beyond the frequencies used by comparable non-echolocators for passive localization.

Duration-sensitive neurons in the inferior colliculus of horseshoe bats: adaptations for using CF-FM echolocation pulses.

PubMed

Luo, Feng; Metzner, Walter; Wu, Feijian; Wu, Feijian J; Zhang, Shuyi; Zhang, Shuyi Y; Chen, Qicai; Chen, Qicai C

2008-01-01

The present study examines duration-sensitive neurons in the inferior colliculus (IC) of the least horseshoe bat, Rhinolophus pusillus, from China. In contrast to other bat species tested for duration selectivity so far, echolocation pulses emitted by horseshoe bats are generally longer and composed of a long constant-frequency (CF) component followed by a short downward frequency-modulated (FM) sweep (CF-FM pulse). We used combined CF-FM pulses to analyze the differential effects that these two pulse components had on the duration tuning in neurons of the horseshoe bat's IC. Consistent with results from other mammals, duration-sensitive neurons found in the least horseshoe bat fall into three main classes: short-pass, band-pass, and long-pass. Using a CF stimulus alone, 54% (51/95) of all IC neurons showed at least one form of duration selectivity at one or more stimulus intensities. In 65 of the 95 IC neurons tested with CF pulses, we were also able to test their duration selectivity for a combined CF-FM pulse, which increased the ratio of duration-sensitive neurons to 66% (43/65). Seven to 15 neurons that failed to show duration tuning for CF bursts became duration sensitive for CF-FM pulses, with most of them exhibiting short-pass (depending on stimulus intensity, between 4 and 8 neurons) or band-pass tuning (1-3 neurons). Increasing stimulus intensities did not affect the duration tuning in 53% (23/43) of duration-sensitive neurons for CF bursts and in about 26% (7/27) for CF-FM stimuli. In the remaining neurons, increasing sound levels generally reduced the ratio of duration-sensitive neurons to 33% for CF and 37% for CF-FM stimulation. In those that remained duration sensitive, louder CF bursts shortened best durations in band-pass neurons and cutoff durations in short- and long-pass neurons, whereas louder CF-FM stimuli reduced the cutoff durations only in short-pass neurons. Bandwidths of band-pass neurons were not significantly affected by any stimulus configuration, with only a slight trend for increasing bandwidths for louder CF bursts (but not CF-FM stimuli). Best durations and cutoff durations reached higher values than those in the other bat species examined so far and roughly match the longer durations of echolocation pulses emitted by horseshoe bats. Therefore presentation of a CF-FM stimulus improved the duration sensitivity in IC neurons by increasing the ratio of duration-tuned neurons and making them less susceptible to changes in signal intensity.

Biosonar navigation above water II: exploiting mirror images.

PubMed

Genzel, Daria; Hoffmann, Susanne; Prosch, Selina; Firzlaff, Uwe; Wiegrebe, Lutz

2015-02-15

As in vision, acoustic signals can be reflected by a smooth surface creating an acoustic mirror image. Water bodies represent the only naturally occurring horizontal and acoustically smooth surfaces. Echolocating bats flying over smooth water bodies encounter echo-acoustic mirror images of objects above the surface. Here, we combined an electrophysiological approach with a behavioral experimental paradigm to investigate whether bats can exploit echo-acoustic mirror images for navigation and how these mirrorlike echo-acoustic cues are encoded in their auditory cortex. In an obstacle-avoidance task where the obstacles could only be detected via their echo-acoustic mirror images, most bats spontaneously exploited these cues for navigation. Sonar ensonifications along the bats' flight path revealed conspicuous changes of the reflection patterns with slightly increased target strengths at relatively long echo delays corresponding to the longer acoustic paths from the mirrored obstacles. Recordings of cortical spatiotemporal response maps (STRMs) describe the tuning of a unit across the dimensions of elevation and time. The majority of cortical single and multiunits showed a special spatiotemporal pattern of excitatory areas in their STRM indicating a preference for echoes with (relative to the setup dimensions) long delays and, interestingly, from low elevations. This neural preference could effectively encode a reflection pattern as it would be perceived by an echolocating bat detecting an object mirrored from below. The current study provides both behavioral and neurophysiological evidence that echo-acoustic mirror images can be exploited by bats for obstacle avoidance. This capability effectively supports echo-acoustic navigation in highly cluttered natural habitats. Copyright © 2015 the American Physiological Society.

Biosonar resolving power: echo-acoustic perception of surface structures in the submillimeter range.

PubMed

Simon, Ralph; Knörnschild, Mirjam; Tschapka, Marco; Schneider, Annkathrin; Passauer, Nadine; Kalko, Elisabeth K V; von Helversen, Otto

2014-01-01

The minimum distance for which two points still can be separated from each other defines the resolving power of a visual system. In an echo-acoustic context, the resolving power is usually measured as the smallest perceivable distance of two reflecting surfaces on the range axis and is found to be around half a millimeter for bats employing frequency modulated (FM) echolocation calls. Only few studies measured such thresholds with physical objects, most often bats were trained on virtual echoes i.e., echoes generated and played back by a computer; moreover, bats were sitting while they received the stimuli. In these studies differences in structure depth between 200 and 340 μm were found. However, these low thresholds were never verified for free-flying bats and real physical objects. Here, we show behavioral evidence that the echo-acoustic resolving power for surface structures in fact can be as low as measured for computer generated echoes and even lower, sometimes below 100 μm. We found this exceptional fine discrimination ability only when one of the targets showed spectral interferences in the frequency range of the bats' echolocation call while the other target did not. This result indicates that surface structure is likely to be perceived as a spectral quality rather than being perceived strictly in the time domain. Further, it points out that sonar resolving power directly depends on the highest frequency/shortest wavelength of the signal employed.

Sonar sound groups and increased terminal buzz duration reflect task complexity in hunting bats.

PubMed

Hulgard, Katrine; Ratcliffe, John M

2016-02-09

More difficult tasks are generally regarded as such because they demand greater attention. Echolocators provide rare insight into this relationship because biosonar signals can be monitored. Here we show that bats produce longer terminal buzzes and more sonar sound groups during their approach to prey under presumably more difficult conditions. Specifically, we found Daubenton's bats, Myotis daubentonii, produced longer buzzes when aerial-hawking versus water-trawling prey, but that bats taking revolving air- and water-borne prey produced more sonar sound groups than did the bats when taking stationary prey. Buzz duration and sonar sound groups have been suggested to be independent means by which bats attend to would-be targets and other objects of interest. We suggest that for attacking bats both should be considered as indicators of task difficulty and that the buzz is, essentially, an extended sonar sound group.

Auditory fovea and Doppler shift compensation: adaptations for flutter detection in echolocating bats using CF-FM signals.

PubMed

Schnitzler, Hans-Ulrich; Denzinger, Annette

2011-05-01

Rhythmical modulations in insect echoes caused by the moving wings of fluttering insects are behaviourally relevant information for bats emitting CF-FM signals with a high duty cycle. Transmitter and receiver of the echolocation system in flutter detecting foragers are especially adapted for the processing of flutter information. The adaptations of the transmitter are indicated by a flutter induced increase in duty cycle, and by Doppler shift compensation (DSC) that keeps the carrier frequency of the insect echoes near a reference frequency. An adaptation of the receiver is the auditory fovea on the basilar membrane, a highly expanded frequency representation centred to the reference frequency. The afferent projections from the fovea lead to foveal areas with an overrepresentation of sharply tuned neurons with best frequencies near the reference frequency throughout the entire auditory pathway. These foveal neurons are very sensitive to stimuli with natural and simulated flutter information. The frequency range of the foveal areas with their flutter processing neurons overlaps exactly with the frequency range where DS compensating bats most likely receive echoes from fluttering insects. This tight match indicates that auditory fovea and DSC are adaptations for the detection and evaluation of insects flying in clutter.

A summary of research investigating echolocation abilities of blind and sighted humans.

PubMed

Kolarik, Andrew J; Cirstea, Silvia; Pardhan, Shahina; Moore, Brian C J

2014-04-01

There is currently considerable interest in the consequences of loss in one sensory modality on the remaining senses. Much of this work has focused on the development of enhanced auditory abilities among blind individuals, who are often able to use sound to navigate through space. It has now been established that many blind individuals produce sound emissions and use the returning echoes to provide them with information about objects in their surroundings, in a similar manner to bats navigating in the dark. In this review, we summarize current knowledge regarding human echolocation. Some blind individuals develop remarkable echolocation abilities, and are able to assess the position, size, distance, shape, and material of objects using reflected sound waves. After training, normally sighted people are also able to use echolocation to perceive objects, and can develop abilities comparable to, but typically somewhat poorer than, those of blind people. The underlying cues and mechanisms, operable range, spatial acuity and neurological underpinnings of echolocation are described. Echolocation can result in functional real life benefits. It is possible that these benefits can be optimized via suitable training, especially among those with recently acquired blindness, but this requires further study. Areas for further research are identified. Copyright © 2014 Elsevier B.V. All rights reserved.

A comparison of survey methods for documenting presence of Myotis leibii (Eastern Small-Footed Bats) at roosting areas in Western Virginia

USGS Publications Warehouse

Huth, John K.; Silvis, Alexander; Moosman, Paul R.; Ford, W. Mark; Sweeten, Sara E.

2015-01-01

Many aspects of foraging and roosting habitat of Myotis leibii (Eastern Small-Footed Bat), an emergent rock roosting-obligate, are poorly described. Previous comparisons of effectiveness of acoustic sampling and mist-net captures have not included Eastern Small-Footed Bat. Habitat requirements of this species differ from congeners in the region, and it is unclear whether survey protocols developed for other species are applicable. Using data from three overlapping studies at two sampling sites in western Virginia’s central Appalachian Mountains, detection probabilities were examined for three survey methods (acoustic surveys with automated identification of calls, visual searches of rock crevices, and mist-netting) for use in the development of “best practices” for future surveys and monitoring. Observer effects were investigated using an expanded version of visual search data. Results suggested that acoustic surveys with automated call identification are not effective for documenting presence of Eastern Small-Footed Bats on talus slopes (basal detection rate of 0%) even when the species is known to be present. The broadband, high frequency echolocation calls emitted by Eastern Small-Footed Bat may be prone to attenuation by virtue of their high frequencies, and these factors, along with signal reflection, lower echolocation rates or possible misidentification to other bat species over talus slopes may all have contributed to poor acoustic survey success. Visual searches and mist-netting of emergent rock had basal detection probabilities of 91% and 75%, respectively. Success of visual searches varied among observers, but detection probability improved with practice. Additionally, visual searches were considerably more economical than mist-netting.

Sequential assessment of prey through the use of multiple sensory cues by an eavesdropping bat

NASA Astrophysics Data System (ADS)

Page, Rachel A.; Schnelle, Tanja; Kalko, Elisabeth K. V.; Bunge, Thomas; Bernal, Ximena E.

2012-06-01

Predators are often confronted with a broad diversity of potential prey. They rely on cues associated with prey quality and palatability to optimize their hunting success and to avoid consuming toxic prey. Here, we investigate a predator's ability to assess prey cues during capture, handling, and consumption when confronted with conflicting information about prey quality. We used advertisement calls of a preferred prey item (the túngara frog) to attract fringe-lipped bats, Trachops cirrhosus, then offered palatable, poisonous, and chemically manipulated anurans as prey. Advertisement calls elicited an attack response, but as bats approached, they used additional sensory cues in a sequential manner to update their information about prey size and palatability. While both palatable and poisonous small anurans were readily captured, large poisonous toads were approached but not contacted suggesting the use of echolocation for assessment of prey size at close range. Once prey was captured, bats used chemical cues to make final, post-capture decisions about whether to consume the prey. Bats dropped small, poisonous toads as well as palatable frogs coated in toad toxins either immediately or shortly after capture. Our study suggests that echolocation and chemical cues obtained at close range supplement information obtained from acoustic cues at long range. Updating information about prey quality minimizes the occurrence of costly errors and may be advantageous in tracking temporal and spatial fluctuations of prey and exploiting novel food sources. These findings emphasize the sequential, complex nature of prey assessment that may allow exploratory and flexible hunting behaviors.

Testing the Sensory Drive Hypothesis: Geographic variation in echolocation frequencies of Geoffroy's horseshoe bat (Rhinolophidae: Rhinolophus clivosus)

PubMed Central

Catto, Sarah; Mutumi, Gregory L.; Finger, Nikita; Webala, Paul W.

2017-01-01

Geographic variation in sensory traits is usually influenced by adaptive processes because these traits are involved in crucial life-history aspects including orientation, communication, lineage recognition and mate choice. Studying this variation can therefore provide insights into lineage diversification. According to the Sensory Drive Hypothesis, lineage diversification may be driven by adaptation of sensory systems to local environments. It predicts that acoustic signals vary in association with local climatic conditions so that atmospheric attenuation is minimized and transmission of the signals maximized. To test this prediction, we investigated the influence of climatic factors (specifically relative humidity and temperature) on geographic variation in the resting frequencies of the echolocation pulses of Geoffroy’s horseshoe bat, Rhinolophus clivosus. If the evolution of phenotypic variation in this lineage tracks climate variation, human induced climate change may lead to decreases in detection volumes and a reduction in foraging efficiency. A complex non-linear interaction between relative humidity and temperature affects atmospheric attenuation of sound and principal components composed of these correlated variables were, therefore, used in a linear mixed effects model to assess their contribution to observed variation in resting frequencies. A principal component composed predominantly of mean annual temperature (factor loading of -0.8455) significantly explained a proportion of the variation in resting frequency across sites (P < 0.05). Specifically, at higher relative humidity (around 60%) prevalent across the distribution of R. clivosus, increasing temperature had a strong negative effect on resting frequency. Climatic factors thus strongly influence acoustic signal divergence in this lineage, supporting the prediction of the Sensory Drive Hypothesis. The predicted future increase in temperature due to climate change is likely to decrease the detection volume in echolocating bats and adversely impact their foraging efficiency. PMID:29186147

Testing the Sensory Drive Hypothesis: Geographic variation in echolocation frequencies of Geoffroy's horseshoe bat (Rhinolophidae: Rhinolophus clivosus).

PubMed

Jacobs, David S; Catto, Sarah; Mutumi, Gregory L; Finger, Nikita; Webala, Paul W

2017-01-01

Geographic variation in sensory traits is usually influenced by adaptive processes because these traits are involved in crucial life-history aspects including orientation, communication, lineage recognition and mate choice. Studying this variation can therefore provide insights into lineage diversification. According to the Sensory Drive Hypothesis, lineage diversification may be driven by adaptation of sensory systems to local environments. It predicts that acoustic signals vary in association with local climatic conditions so that atmospheric attenuation is minimized and transmission of the signals maximized. To test this prediction, we investigated the influence of climatic factors (specifically relative humidity and temperature) on geographic variation in the resting frequencies of the echolocation pulses of Geoffroy's horseshoe bat, Rhinolophus clivosus. If the evolution of phenotypic variation in this lineage tracks climate variation, human induced climate change may lead to decreases in detection volumes and a reduction in foraging efficiency. A complex non-linear interaction between relative humidity and temperature affects atmospheric attenuation of sound and principal components composed of these correlated variables were, therefore, used in a linear mixed effects model to assess their contribution to observed variation in resting frequencies. A principal component composed predominantly of mean annual temperature (factor loading of -0.8455) significantly explained a proportion of the variation in resting frequency across sites (P < 0.05). Specifically, at higher relative humidity (around 60%) prevalent across the distribution of R. clivosus, increasing temperature had a strong negative effect on resting frequency. Climatic factors thus strongly influence acoustic signal divergence in this lineage, supporting the prediction of the Sensory Drive Hypothesis. The predicted future increase in temperature due to climate change is likely to decrease the detection volume in echolocating bats and adversely impact their foraging efficiency.

Echolocation of insects using intermittent frequency-modulated sounds.

PubMed

Matsuo, Ikuo; Takanashi, Takuma

2015-09-01

Using echolocation influenced by Doppler shift, bats can capture flying insects in real three-dimensional space. On the basis of this principle, a model that estimates object locations using frequency modulated (FM) sound was proposed. However, no investigation was conducted to verify whether the model can localize flying insects from their echoes. This study applied the model to estimate the range and direction of flying insects by extracting temporal changes from the time-frequency pattern and interaural range difference, respectively. The results obtained confirm that a living insect's position can be estimated using this model with echoes measured while emitting intermittent FM sounds.

Evolution of deceptive and true courtship songs in moths

PubMed Central

Nakano, Ryo; Takanashi, Takuma; Surlykke, Annemarie; Skals, Niels; Ishikawa, Yukio

2013-01-01

Ultrasonic mating signals in moths are argued to have evolved via exploitation of the receivers' sensory bias towards bat echolocation calls. We have demonstrated that female moths of the Asian corn borer are unable to distinguish between the male courtship song and bat calls. Females react to both the male song and bat calls by “freezing”, which males take advantage of in mating (deceptive courtship song). In contrast, females of the Japanese lichen moth are able to distinguish between the male song and bat calls by the structure of the sounds; females emit warning clicks against bats, but accept males (true courtship song). Here, we propose a hypothesis that deceptive and true signals evolved independently from slightly different precursory sounds; deceptive/true courtship songs in moths evolved from the sounds males incidentally emitted in a sexual context, which females could not/could distinguish, respectively, from bat calls. PMID:23788180

Echolocation in humans: an overview.

PubMed

Thaler, Lore; Goodale, Melvyn A

2016-11-01

Bats and dolphins are known for their ability to use echolocation. They emit bursts of sounds and listen to the echoes that bounce back to detect the objects in their environment. What is not as well-known is that some blind people have learned to do the same thing, making mouth clicks, for example, and using the returning echoes from those clicks to sense obstacles and objects of interest in their surroundings. The current review explores some of the research that has examined human echolocation and the changes that have been observed in the brains of echolocation experts. We also discuss potential applications and assistive technology based on echolocation. Blind echolocation experts can sense small differences in the location of objects, differentiate between objects of various sizes and shapes, and even between objects made of different materials, just by listening to the reflected echoes from mouth clicks. It is clear that echolocation may enable some blind people to do things that are otherwise thought to be impossible without vision, potentially providing them with a high degree of independence in their daily lives and demonstrating that echolocation can serve as an effective mobility strategy in the blind. Neuroimaging has shown that the processing of echoes activates brain regions in blind echolocators that would normally support vision in the sighted brain, and that the patterns of these activations are modulated by the information carried by the echoes. This work is shedding new light on just how plastic the human brain is. WIREs Cogn Sci 2016, 7:382-393. doi: 10.1002/wcs.1408 For further resources related to this article, please visit the WIREs website. © 2016 Wiley Periodicals, Inc.

Human Exploration of Enclosed Spaces through Echolocation.

PubMed

Flanagin, Virginia L; Schörnich, Sven; Schranner, Michael; Hummel, Nadine; Wallmeier, Ludwig; Wahlberg, Magnus; Stephan, Thomas; Wiegrebe, Lutz

2017-02-08

Some blind humans have developed echolocation, as a method of navigation in space. Echolocation is a truly active sense because subjects analyze echoes of dedicated, self-generated sounds to assess space around them. Using a special virtual space technique, we assess how humans perceive enclosed spaces through echolocation, thereby revealing the interplay between sensory and vocal-motor neural activity while humans perform this task. Sighted subjects were trained to detect small changes in virtual-room size analyzing real-time generated echoes of their vocalizations. Individual differences in performance were related to the type and number of vocalizations produced. We then asked subjects to estimate virtual-room size with either active or passive sounds while measuring their brain activity with fMRI. Subjects were better at estimating room size when actively vocalizing. This was reflected in the hemodynamic activity of vocal-motor cortices, even after individual motor and sensory components were removed. Activity in these areas also varied with perceived room size, although the vocal-motor output was unchanged. In addition, thalamic and auditory-midbrain activity was correlated with perceived room size; a likely result of top-down auditory pathways for human echolocation, comparable with those described in echolocating bats. Our data provide evidence that human echolocation is supported by active sensing, both behaviorally and in terms of brain activity. The neural sensory-motor coupling complements the fundamental acoustic motor-sensory coupling via the environment in echolocation. SIGNIFICANCE STATEMENT Passive listening is the predominant method for examining brain activity during echolocation, the auditory analysis of self-generated sounds. We show that sighted humans perform better when they actively vocalize than during passive listening. Correspondingly, vocal motor and cerebellar activity is greater during active echolocation than vocalization alone. Motor and subcortical auditory brain activity covaries with the auditory percept, although motor output is unchanged. Our results reveal behaviorally relevant neural sensory-motor coupling during echolocation. Copyright © 2017 the authors 0270-6474/17/371614-14$15.00/0.

Behavioural and neurobiological implications of linear and non-linear features in larynx phonations of horseshoe bats

PubMed Central

Kobayasi, Kohta I.; Hage, Steffen R.; Berquist, Sean; Feng, Jiang; Zhang, Shuyi; Metzner, Walter

2012-01-01

Mammalian vocalizations exhibit large variations in their spectrotemporal features, although it is still largely unknown which result from intrinsic biomechanical properties of the larynx and which are under direct neuromuscular control. Here we show that mere changes in laryngeal air flow yield several non-linear effects on sound production, in an isolated larynx preparation from horseshoe bats. Most notably, there are sudden jumps between two frequency bands used for either echolocation or communication in natural vocalizations. These jumps resemble changes in “registers” as in yodelling. In contrast, simulated contractions of the main larynx muscle produce linear frequency changes, but are limited to echolocation or communication frequencies. Only by combining non-linear and linear properties can this larynx therefore produce sounds covering the entire frequency range of natural calls. This may give behavioural meaning to yodelling-like vocal behaviour and reshape our thinking about how the brain controls the multitude of spectral vocal features in mammals. PMID:23149729

Stimulation of the basal and central amygdala in the mustached bat triggers echolocation and agonistic vocalizations within multimodal output

PubMed Central

Ma, Jie; Kanwal, Jagmeet S.

2014-01-01

The neural substrate for the perception of vocalizations is relatively well described, but how their timing and specificity are tightly coupled with accompanying physiological changes and context-appropriate behaviors remains unresolved. We hypothesized that temporally integrated vocal and emotive responses, especially the expression of fear, vigilance and aggression, originate within the amygdala. To test this hypothesis, we performed electrical microstimulation at 461 highly restricted loci within the basal and central amygdala in awake mustached bats. At a subset of these sites, high frequency stimulation with weak constant current pulses presented at near-threshold levels triggered vocalization of either echolocation pulses or social calls. At the vast majority of locations, microstimulation produced a constellation of changes in autonomic and somatomotor outputs. These changes included widespread co-activation of significant tachycardia and hyperventilation and/or rhythmic ear pinna movements (PMs). In a few locations, responses were constrained to vocalization and/or PMs despite increases in the intensity of stimulation. The probability of eliciting echolocation pulses vs. social calls decreased in a medial-posterior to anterolateral direction within the centrobasal amygdala. Microinjections of kainic acid (KA) at stimulation sites confirmed the contribution of cellular activity rather than fibers-of-passage in the control of multimodal outputs. The results suggest that localized clusters of neurons may simultaneously modulate the activity of multiple central pattern generators (CPGs) present within the brainstem. PMID:24624089

Stimulation of the basal and central amygdala in the mustached bat triggers echolocation and agonistic vocalizations within multimodal output.

PubMed

Ma, Jie; Kanwal, Jagmeet S

2014-01-01

The neural substrate for the perception of vocalizations is relatively well described, but how their timing and specificity are tightly coupled with accompanying physiological changes and context-appropriate behaviors remains unresolved. We hypothesized that temporally integrated vocal and emotive responses, especially the expression of fear, vigilance and aggression, originate within the amygdala. To test this hypothesis, we performed electrical microstimulation at 461 highly restricted loci within the basal and central amygdala in awake mustached bats. At a subset of these sites, high frequency stimulation with weak constant current pulses presented at near-threshold levels triggered vocalization of either echolocation pulses or social calls. At the vast majority of locations, microstimulation produced a constellation of changes in autonomic and somatomotor outputs. These changes included widespread co-activation of significant tachycardia and hyperventilation and/or rhythmic ear pinna movements (PMs). In a few locations, responses were constrained to vocalization and/or PMs despite increases in the intensity of stimulation. The probability of eliciting echolocation pulses vs. social calls decreased in a medial-posterior to anterolateral direction within the centrobasal amygdala. Microinjections of kainic acid (KA) at stimulation sites confirmed the contribution of cellular activity rather than fibers-of-passage in the control of multimodal outputs. The results suggest that localized clusters of neurons may simultaneously modulate the activity of multiple central pattern generators (CPGs) present within the brainstem.

Biosonar resolving power: echo-acoustic perception of surface structures in the submillimeter range

PubMed Central

Simon, Ralph; Knörnschild, Mirjam; Tschapka, Marco; Schneider, Annkathrin; Passauer, Nadine; Kalko, Elisabeth K. V.; von Helversen, Otto

2014-01-01

The minimum distance for which two points still can be separated from each other defines the resolving power of a visual system. In an echo-acoustic context, the resolving power is usually measured as the smallest perceivable distance of two reflecting surfaces on the range axis and is found to be around half a millimeter for bats employing frequency modulated (FM) echolocation calls. Only few studies measured such thresholds with physical objects, most often bats were trained on virtual echoes i.e., echoes generated and played back by a computer; moreover, bats were sitting while they received the stimuli. In these studies differences in structure depth between 200 and 340 μm were found. However, these low thresholds were never verified for free-flying bats and real physical objects. Here, we show behavioral evidence that the echo-acoustic resolving power for surface structures in fact can be as low as measured for computer generated echoes and even lower, sometimes below 100 μm. We found this exceptional fine discrimination ability only when one of the targets showed spectral interferences in the frequency range of the bats′ echolocation call while the other target did not. This result indicates that surface structure is likely to be perceived as a spectral quality rather than being perceived strictly in the time domain. Further, it points out that sonar resolving power directly depends on the highest frequency/shortest wavelength of the signal employed. PMID:24616703

Target representation of naturalistic echolocation sequences in single unit responses from the inferior colliculus of big brown bats

NASA Astrophysics Data System (ADS)

Sanderson, Mark I.; Simmons, James A.

2005-11-01

Echolocating big brown bats (Eptesicus fuscus) emit trains of frequency-modulated (FM) biosonar signals whose duration, repetition rate, and sweep structure change systematically during interception of prey. When stimulated with a 2.5-s sequence of 54 FM pulse-echo pairs that mimic sounds received during search, approach, and terminal stages of pursuit, single neurons (N=116) in the bat's inferior colliculus (IC) register the occurrence of a pulse or echo with an average of <1 spike/sound. Individual IC neurons typically respond to only a segment of the search or approach stage of pursuit, with fewer neurons persisting to respond in the terminal stage. Composite peristimulus-time-histogram plots of responses assembled across the whole recorded population of IC neurons depict the delay of echoes and, hence, the existence and distance of the simulated biosonar target, entirely as on-response latencies distributed across time. Correlated changes in pulse duration, repetition rate, and pulse or echo amplitude do modulate the strength of responses (probability of the single spike actually occurring for each sound), but registration of the target itself remains confined exclusively to the latencies of single spikes across cells. Modeling of echo processing in FM biosonar should emphasize spike-time algorithms to explain the content of biosonar images.

An echolocation model for the restoration of an acoustic image from a single-emission echo

NASA Astrophysics Data System (ADS)

Matsuo, Ikuo; Yano, Masafumi

2004-12-01

Bats can form a fine acoustic image of an object using frequency-modulated echolocation sound. The acoustic image is an impulse response, known as a reflected-intensity distribution, which is composed of amplitude and phase spectra over a range of frequencies. However, bats detect only the amplitude spectrum due to the low-time resolution of their peripheral auditory system, and the frequency range of emission is restricted. It is therefore necessary to restore the acoustic image from limited information. The amplitude spectrum varies with the changes in the configuration of the reflected-intensity distribution, while the phase spectrum varies with the changes in its configuration and location. Here, by introducing some reasonable constraints, a method is proposed for restoring an acoustic image from the echo. The configuration is extrapolated from the amplitude spectrum of the restricted frequency range by using the continuity condition of the amplitude spectrum at the minimum frequency of the emission and the minimum phase condition. The determination of the location requires extracting the amplitude spectra, which vary with its location. For this purpose, the Gaussian chirplets with a carrier frequency compatible with bat emission sweep rates were used. The location is estimated from the temporal changes of the amplitude spectra. .

Pursuit, Avoidance, and Cohesion in Flight: Multi-Purpose Control Laws and Neuromorphic VLSI

DTIC Science & Technology

2010-10-01

34 Binaural Spectral Cues for Ultrasonic Localization," Proc. International Symposium on Circuits and Systems, pp. 2110 - 2113, 2008 (DOI:10.1109/ISCAS...T. K. Horiuchi, C. Bansal, and T. M. Massoud (2009), " Binaural Intensity Comparison in the Echolocating Bat Using Synaptic Conductance," Proc

Optimal Predator Risk Assessment by the Sonar-Jamming Arctiine Moth Bertholdia trigona

PubMed Central

Corcoran, Aaron J.; Wagner, Ryan D.; Conner, William E.

2013-01-01

Nearly all animals face a tradeoff between seeking food and mates and avoiding predation. Optimal escape theory holds that an animal confronted with a predator should only flee when benefits of flight (increased survival) outweigh the costs (energetic costs, lost foraging time, etc.). We propose a model for prey risk assessment based on the predator's stage of attack. Risk level should increase rapidly from when the predator detects the prey to when it commits to the attack. We tested this hypothesis using a predator – the echolocating bat – whose active biosonar reveals its stage of attack. We used a prey defense – clicking used for sonar jamming by the tiger moth Bertholdia trigona– that can be readily studied in the field and laboratory and is enacted simultaneously with evasive flight. We predicted that prey employ defenses soon after being detected and targeted, and that prey defensive thresholds discriminate between legitimate predatory threats and false threats where a nearby prey is attacked. Laboratory and field experiments using playbacks of ultrasound signals and naturally behaving bats, respectively, confirmed our predictions. Moths clicked soon after bats detected and targeted them. Also, B. trigona clicking thresholds closely matched predicted optimal thresholds for discriminating legitimate and false predator threats for bats using search and approach phase echolocation – the period when bats are searching for and assessing prey. To our knowledge, this is the first quantitative study to correlate the sensory stimuli that trigger defensive behaviors with measurements of signals provided by predators during natural attacks in the field. We propose theoretical models for explaining prey risk assessment depending on the availability of cues that reveal a predator's stage of attack. PMID:23671686

Ultraviolet vision may be widespread in bats

USGS Publications Warehouse

Gorresen, P. Marcos; Cryan, Paul; Dalton, David C.; Wolf, Sandy; Bonaccorso, Frank

2015-01-01

Insectivorous bats are well known for their abilities to find and pursue flying insect prey at close range using echolocation, but they also rely heavily on vision. For example, at night bats use vision to orient across landscapes, avoid large obstacles, and locate roosts. Although lacking sharp visual acuity, the eyes of bats evolved to function at very low levels of illumination. Recent evidence based on genetics, immunohistochemistry, and laboratory behavioral trials indicated that many bats can see ultraviolet light (UV), at least at illumination levels similar to or brighter than those before twilight. Despite this growing evidence for potentially widespread UV vision in bats, the prevalence of UV vision among bats remains unknown and has not been studied outside of the laboratory. We used a Y-maze to test whether wild-caught bats could see reflected UV light and whether such UV vision functions at the dim lighting conditions typically experienced by night-flying bats. Seven insectivorous species of bats, representing five genera and three families, showed a statistically significant ‘escape-toward-the-light’ behavior when placed in the Y-maze. Our results provide compelling evidence of widespread dim-light UV vision in bats.

High-frequency modulated signals of killer whales (Orcinus orca) in the North Pacific.

PubMed

Simonis, Anne E; Baumann-Pickering, Simone; Oleson, Erin; Melcón, Mariana L; Gassmann, Martin; Wiggins, Sean M; Hildebrand, John A

2012-04-01

Killer whales in the North Pacific, similar to Atlantic populations, produce high-frequency modulated signals, based on acoustic recordings from ship-based hydrophone arrays and autonomous recorders at multiple locations. The median peak frequency of these signals ranged from 19.6-36.1 kHz and median duration ranged from 50-163 ms. Source levels were 185-193 dB peak-to-peak re: 1 μPa at 1 m. These uniform, repetitive, down-swept signals are similar to bat echolocation signals and possibly could have echolocation functionality. A large geographic range of occurrence suggests that different killer whale ecotypes may utilize these signals.

Topography of sound level representation in the FM sweep selective region of the pallid bat auditory cortex.

PubMed

Measor, Kevin; Yarrow, Stuart; Razak, Khaleel A

2018-05-26

Sound level processing is a fundamental function of the auditory system. To determine how the cortex represents sound level, it is important to quantify how changes in level alter the spatiotemporal structure of cortical ensemble activity. This is particularly true for echolocating bats that have control over, and often rapidly adjust, call level to actively change echo level. To understand how cortical activity may change with sound level, here we mapped response rate and latency changes with sound level in the auditory cortex of the pallid bat. The pallid bat uses a 60-30 kHz downward frequency modulated (FM) sweep for echolocation. Neurons tuned to frequencies between 30 and 70 kHz in the auditory cortex are selective for the properties of FM sweeps used in echolocation forming the FM sweep selective region (FMSR). The FMSR is strongly selective for sound level between 30 and 50 dB SPL. Here we mapped the topography of level selectivity in the FMSR using downward FM sweeps and show that neurons with more monotonic rate level functions are located in caudomedial regions of the FMSR overlapping with high frequency (50-60 kHz) neurons. Non-monotonic neurons dominate the FMSR, and are distributed across the entire region, but there is no evidence for amplitopy. We also examined how first spike latency of FMSR neurons change with sound level. The majority of FMSR neurons exhibit paradoxical latency shift wherein the latency increases with sound level. Moreover, neurons with paradoxical latency shifts are more strongly level selective and are tuned to lower sound level than neurons in which latencies decrease with level. These data indicate a clustered arrangement of neurons according to monotonicity, with no strong evidence for finer scale topography, in the FMSR. The latency analysis suggests mechanisms for strong level selectivity that is based on relative timing of excitatory and inhibitory inputs. Taken together, these data suggest how the spatiotemporal spread of cortical activity may represent sound level. Copyright © 2018. Published by Elsevier B.V.

Suppression of emission rates improves sonar performance by flying bats.

PubMed

Adams, Amanda M; Davis, Kaylee; Smotherman, Michael

2017-01-31

Echolocating bats face the challenge of actively sensing their environment through their own emissions, while also hearing calls and echoes of nearby conspecifics. How bats mitigate interference is a long-standing question that has both ecological and technological implications, as biosonar systems continue to outperform man-made sonar systems in noisy, cluttered environments. We recently showed that perched bats decreased calling rates in groups, displaying a behavioral strategy resembling the back-off algorithms used in artificial communication networks to optimize information throughput at the group level. We tested whether free-tailed bats (Tadarida brasiliensis) would employ such a coordinated strategy while performing challenging flight maneuvers, and report here that bats navigating obstacles lowered emission rates when hearing artificial playback of another bat's calls. We measured the impact of acoustic interference on navigation performance and show that the calculated reductions in interference rates are sufficient to reduce interference and improve obstacle avoidance. When bats flew in pairs, each bat responded to the presence of the other as an obstacle by increasing emissions, but hearing the sonar emissions of the nearby bat partially suppressed this response. This behavior supports social cohesion by providing a key mechanism for minimizing mutual interference.

Sensory trait variation in an echolocating bat suggests roles for both selection and plasticity

PubMed Central

2014-01-01

Background Across heterogeneous environments selection and gene flow interact to influence the rate and extent of adaptive trait evolution. This complex relationship is further influenced by the rarely considered role of phenotypic plasticity in the evolution of adaptive population variation. Plasticity can be adaptive if it promotes colonization and survival in novel environments and in doing so may increase the potential for future population differentiation via selection. Gene flow between selectively divergent environments may favour the evolution of phenotypic plasticity or conversely, plasticity itself may promote gene flow, leading to a pattern of trait differentiation in the presence of gene flow. Variation in sensory traits is particularly informative in testing the role of environment in trait and population differentiation. Here we test the hypothesis of ‘adaptive differentiation with minimal gene flow’ in resting echolocation frequencies (RF) of Cape horseshoe bats (Rhinolophus capensis) across a gradient of increasingly cluttered habitats. Results Our analysis reveals a geographically structured pattern of increasing RF from open to highly cluttered habitats in R. capensis; however genetic drift appears to be a minor player in the processes influencing this pattern. Although Bayesian analysis of population structure uncovered a number of spatially defined mitochondrial groups and coalescent methods revealed regional-scale gene flow, phylogenetic analysis of mitochondrial sequences did not correlate with RF differentiation. Instead, habitat discontinuities between biomes, and not genetic and geographic distances, best explained echolocation variation in this species. We argue that both selection for increased detection distance in relatively less cluttered habitats and adaptive phenotypic plasticity may have influenced the evolution of matched echolocation frequencies and habitats across different populations. Conclusions Our study reveals significant sensory trait differentiation in the presence of historical gene flow and suggests roles for both selection and plasticity in the evolution of echolocation variation in R. capensis. These results highlight the importance of population level analyses to i) illuminate the subtle interplay between selection, plasticity and gene flow in the evolution of adaptive traits and ii) demonstrate that evolutionary processes may act simultaneously and that their relative influence may vary across different environments. PMID:24674227

Sensory trait variation in an echolocating bat suggests roles for both selection and plasticity.

PubMed

Odendaal, Lizelle J; Jacobs, David S; Bishop, Jacqueline M

2014-03-27

Across heterogeneous environments selection and gene flow interact to influence the rate and extent of adaptive trait evolution. This complex relationship is further influenced by the rarely considered role of phenotypic plasticity in the evolution of adaptive population variation. Plasticity can be adaptive if it promotes colonization and survival in novel environments and in doing so may increase the potential for future population differentiation via selection. Gene flow between selectively divergent environments may favour the evolution of phenotypic plasticity or conversely, plasticity itself may promote gene flow, leading to a pattern of trait differentiation in the presence of gene flow. Variation in sensory traits is particularly informative in testing the role of environment in trait and population differentiation. Here we test the hypothesis of 'adaptive differentiation with minimal gene flow' in resting echolocation frequencies (RF) of Cape horseshoe bats (Rhinolophus capensis) across a gradient of increasingly cluttered habitats. Our analysis reveals a geographically structured pattern of increasing RF from open to highly cluttered habitats in R. capensis; however genetic drift appears to be a minor player in the processes influencing this pattern. Although Bayesian analysis of population structure uncovered a number of spatially defined mitochondrial groups and coalescent methods revealed regional-scale gene flow, phylogenetic analysis of mitochondrial sequences did not correlate with RF differentiation. Instead, habitat discontinuities between biomes, and not genetic and geographic distances, best explained echolocation variation in this species. We argue that both selection for increased detection distance in relatively less cluttered habitats and adaptive phenotypic plasticity may have influenced the evolution of matched echolocation frequencies and habitats across different populations. Our study reveals significant sensory trait differentiation in the presence of historical gene flow and suggests roles for both selection and plasticity in the evolution of echolocation variation in R. capensis. These results highlight the importance of population level analyses to i) illuminate the subtle interplay between selection, plasticity and gene flow in the evolution of adaptive traits and ii) demonstrate that evolutionary processes may act simultaneously and that their relative influence may vary across different environments.

Echolocation with bat buzz emissions: model and biomimetic sonar for elevation estimation.

PubMed

Kuc, Roman

2012-01-01

Just prior to capture the Buzz II emissions of some mouth-emitting bats, such as Eptesicus fuscus, are observed to exhibit spectra having multiple peaks. This paper proposes an echolocation strategy that uses such spectra with energy concentrated in specific frequency bands for determining target elevation. A biomimetic sonar was implemented to produce a tri-modal spectrum by driving a speaker with a signal rich in harmonics. The emission magnitudes at these harmonic frequencies measured as a function of elevation in the zero-azimuth plane form distinct beams. A template was formed from the ratio of the first harmonic and fundamental magnitudes to determine elevation. The elevation estimator exhibited a sub-degree accuracy (SD = 0.4° over a 20° interval centered at the elevation at which these two beams intersect in the zero-azimuth plane. Spectral cues from -40° to +10° elevation allow a qualitative non-linear control of sonar orientation to drive the target to the beam-intersection point where quantitative elevation estimates are available. © 2012 Acoustical Society of America.

Ambient noise induces independent shifts in call frequency and amplitude within the Lombard effect in echolocating bats

PubMed Central

Hage, Steffen R.; Jiang, Tinglei; Berquist, Sean W.; Feng, Jiang; Metzner, Walter

2013-01-01

The Lombard effect, an involuntary rise in call amplitude in response to masking ambient noise, represents one of the most efficient mechanisms to optimize signal-to-noise ratio. The Lombard effect occurs in birds and mammals, including humans, and is often associated with several other vocal changes, such as call frequency and duration. Most studies, however, have focused on noise-dependent changes in call amplitude. It is therefore still largely unknown how the adaptive changes in call amplitude relate to associated vocal changes such as frequency shifts, how the underlying mechanisms are linked, and if auditory feedback from the changing vocal output is needed. Here, we examined the Lombard effect and the associated changes in call frequency in a highly vocal mammal, echolocating horseshoe bats. We analyzed how bandpass-filtered noise (BFN; bandwidth 20 kHz) affected their echolocation behavior when BFN was centered on different frequencies within their hearing range. Call amplitudes increased only when BFN was centered on the dominant frequency component of the bats’ calls. In contrast, call frequencies increased for all but one BFN center frequency tested. Both amplitude and frequency rises were extremely fast and occurred in the first call uttered after noise onset, suggesting that no auditory feedback was required. The different effects that varying the BFN center frequency had on amplitude and frequency rises indicate different neural circuits and/or mechanisms underlying these changes. PMID:23431172

Suppression of emission rates improves sonar performance by flying bats

PubMed Central

Adams, Amanda M.; Davis, Kaylee; Smotherman, Michael

2017-01-01

Echolocating bats face the challenge of actively sensing their environment through their own emissions, while also hearing calls and echoes of nearby conspecifics. How bats mitigate interference is a long-standing question that has both ecological and technological implications, as biosonar systems continue to outperform man-made sonar systems in noisy, cluttered environments. We recently showed that perched bats decreased calling rates in groups, displaying a behavioral strategy resembling the back-off algorithms used in artificial communication networks to optimize information throughput at the group level. We tested whether free-tailed bats (Tadarida brasiliensis) would employ such a coordinated strategy while performing challenging flight maneuvers, and report here that bats navigating obstacles lowered emission rates when hearing artificial playback of another bat’s calls. We measured the impact of acoustic interference on navigation performance and show that the calculated reductions in interference rates are sufficient to reduce interference and improve obstacle avoidance. When bats flew in pairs, each bat responded to the presence of the other as an obstacle by increasing emissions, but hearing the sonar emissions of the nearby bat partially suppressed this response. This behavior supports social cohesion by providing a key mechanism for minimizing mutual interference. PMID:28139707

How the bat got its buzz

PubMed Central

Ratcliffe, John M.; Elemans, Coen P. H.; Jakobsen, Lasse; Surlykke, Annemarie

2013-01-01

Since the discovery of echolocation in bats, the final phase of an attack on a flying insect, the ‘terminal buzz’, has proved enigmatic. During the buzz, bats increase information update rates by producing vocalizations up to 220 times s−1. The buzz's ubiquity in hawking and trawling bats implies its importance for hunting success. Superfast muscles, previously unknown in mammals, are responsible for the extreme vocalization rate. Some bats produce a second phase—buzz II—defined by a large drop in the fundamental frequency (F0) of their calls. By doing so, bats broaden their acoustic field of view and should thereby reduce the likelihood of insect escape. We make the case that the buzz was a critical adaptation for capturing night-flying insects, and suggest that the drop in F0 during buzz II requires novel, unidentified laryngeal mechanisms in order to counteract increasing muscle tension. Furthermore, we propose that buzz II represents a countermeasure against the evasive flight of eared prey in the evolutionary arms-race that saw the independent evolution of bat-detecting ears in various groups of night-flying insects. PMID:23302868

Neural Computations for Biosonar Imaging in the Big Brown Bat

NASA Astrophysics Data System (ADS)

Saillant, Prestor Augusto

1995-11-01

The study of the intimate relationship between space and time has taken many forms, ranging from the Theory of Relativity down to the problem of avoiding traffic jams. However, nowhere has this relationship been more fully developed and exploited than in dolphins and bats, which have the ability to utilize biosonar. This thesis describes research on the behavioral and computational basis of echolocation carried out in order to explore the neural mechanisms which may account for the space-time constructs which are of psychological importance to the big brown bat. The SCAT (Spectrogram Correlation and Transformation) computational model was developed to provide a framework for understanding the computational requirements of FM echolocation as determined from psychophysical experiments (i.e., high resolution imaging) and neurobiological constraints (Saillant et al., 1993). The second part of the thesis consisted in developing a new behavioral paradigm for simultaneously studying acoustic behavior and flight behavior of big brown bats in pursuit of stationary or moving targets. In the third part of the thesis a complete acoustic "artificial bat" was constructed, making use of the SCAT process. The development of the artificial bat allowed us to begin experimentation with real world echoes from various targets, in order to gain a better appreciation for the additional complexities and sources of information encountered by bats in flight. Finally, the continued development of the SCAT model has allowed a deeper understanding of the phenomenon of "time expansion" and of the phenomenon of phase sensitivity in the ultrasonic range. Time expansion, first predicted through the use of the SCAT model, and later found in auditory local evoked potential recordings, opens up a new realm of information processing and representation in the brain which as of yet has not been considered. It seems possible, from the work in the auditory system, that time expansion may provide a novel perceptual substrate, such that information processed at higher speeds than typically accepted in the brain, is not perceived (or perhaps remembered) until it is represented in time expanded form. This phenomenon can be described as a "temporal zoom lens" effect.

Aerial hawking and landing: approach behaviour in Natterer's bats, Myotis nattereri (Kuhl 1818).

PubMed

Melcón, Mariana L; Denzinger, Annette; Schnitzler, Hans-Ulrich

2007-12-01

We compared the flight and echolocation behaviour of a vespertilionid bat (Myotis nattereri) approaching a large stationary or a small moving target. Bats were trained to either land on a landing grid or to catch a moving tethered mealworm. When closing in on these two targets, the bats emitted groups of sounds with increasing number of signals and decreasing pulse interval and duration. When pursuing the mealworm, the approach phase always ended with a terminal group consisting of buzz I and buzz II. When landing, the bats emitted either a terminal group consisting of buzz I alone, with one or two extra pulses, or a group consisting of buzz I and buzz II. In all situations, buzz I ended on average between 47-63 ms prior to contact with the target of interest, which is approximately the reaction time of bats. Therefore, the information collected in buzz II does not guide the bats to the target. The relevant part of the approach phase to reach the target ends with buzz I. The basic sound pattern of this part is rather similar and independent of whether the bats approach the large stationary or the small moving target.

Prey pursuit strategy of Japanese horseshoe bats during an in-flight target-selection task.

PubMed

Kinoshita, Yuki; Ogata, Daiki; Watanabe, Yoshiaki; Riquimaroux, Hiroshi; Ohta, Tetsuo; Hiryu, Shizuko

2014-09-01

The prey pursuit behavior of Japanese horseshoe bats (Rhinolophus ferrumequinum nippon) was investigated by tasking bats during flight with choosing between two tethered fluttering moths. Echolocation pulses were recorded using a telemetry microphone mounted on the bat combined with a 17-channel horizontal microphone array to measure pulse directions. Flight paths of the bat and moths were monitored using two high-speed video cameras. Acoustical measurements of returning echoes from fluttering moths were first collected using an ultrasonic loudspeaker, turning the head direction of the moth relative to the loudspeaker from 0° (front) to 180° (back) in the horizontal plane. The amount of acoustical glints caused by moth fluttering varied with the sound direction, reaching a maximum at 70°-100° in the horizontal plane. In the flight experiment, moths chosen by the bat fluttered within or moved across these angles relative to the bat's pulse direction, which would cause maximum dynamic changes in the frequency and amplitude of acoustical glints during flight. These results suggest that echoes with acoustical glints containing the strongest frequency and amplitude modulations appear to attract bats for prey selection.

Buzzing during biosonar-based interception of prey in the delphinids Tursiops truncatus and Pseudorca crassidens.

PubMed

Wisniewska, Danuta M; Johnson, Mark; Nachtigall, Paul E; Madsen, Peter T

2014-12-15

Echolocating bats and toothed whales probe their environment with ultrasonic sound pulses, using returning echoes to navigate and find prey in a process that appears to have resulted from a remarkable convergence of the two taxa. Here, we report the first detailed quantification of echolocation behaviour during prey capture in the most studied delphinid species, a false killer whale and a bottlenose dolphin. Using acoustic DTAGs, we demonstrate that just prior to prey interception these delphinids change their acoustic gaze dramatically by reducing inter-click intervals and output >10-fold in a high repetition rate, low output buzz. Buzz click rates of 250-500 Hz for large but agile animals suggest that sampling rates during capture are scaled with the whale's manoeuvrability. These observations support the growing notion that fast sonar sampling accompanied by a low output level is critical for high rate feedback to inform motor patterns during prey interception in all echolocating toothed whales. © 2014. Published by The Company of Biologists Ltd.

Behavioral responses of big brown bats to dives by praying mantises.

PubMed

Ghose, Kaushik; Triblehorn, Jeffrey D; Bohn, Kari; Yager, David D; Moss, Cynthia F

2009-03-01

Insectivorous echolocating bats face a formidable array of defenses employed by their airborne prey. One such insect defense is the ultrasound-triggered dive, which is a sudden, rapid drop in altitude, sometimes all the way to the ground. Although many previous studies have investigated the dynamics of such dives and their effect on insect survival rate, there has been little work on how bats may adapt to such an insect defense employed in the middle of pursuit. In this study we investigated how big brown bats (Eptesicus fuscus) adjust their pursuit strategy when flying praying mantises (Parasphendale agrionina) execute evasive, ultrasound-triggered dives. Although the mantis dive occasionally forced the bat to completely abort its chase (25% trials), in a number of cases (75% trials) the bat followed the mantis into the dive. In such cases the bat kept its sonar beam locked onto the target and maneuvered to maintain the same time efficient strategy it adopted during level flight pursuit, though it was ultimately defeated by the dive. This study suggests that although the mantis dive can be effective in evading the bat, it does not always deter the bat from continuing pursuit and, given enough altitude, the bat can potentially capture diving prey using the same flight strategy it employs to intercept prey in level flight.

A Biomimetic Ultrasonic Whistle for Use as a Bat Deterrent on Wind Turbines

NASA Astrophysics Data System (ADS)

Sievert, Paul; Seyed-Aghazadeh, Banafsheh; Carlson, Daniel; Dowling, Zara; Modarres-Sadeghi, Yahya

2016-11-01

As wind energy continues to gain worldwide prominence, more and more turbines are detrimentally influencing bat colonies. In 2012 alone, an estimated 600,000 bats were killed by wind turbines in the United States. Bats show a tendency to fly towards turbines. The objective of this work is to deter bats from the proximity of the swept area of operational wind turbine blades. Established field studies have shown that bats avoid broadband ultrasonic noise on the same frequency spectrum as their echolocation chirps. A biomimetic ultrasonic pulse generator for use as a bat deterrent on wind turbines is designed and studied experimentally. This device, which works based on the fundamentals of flow-induced oscillations of a flexible sheet is a whistle-like device inspired by a bat larynx, mechanically powered via air flow on a wind turbine blade. Current device prototypes have proven robust at producing ultrasound across the 20 - 70 kHz range for flow inlet velocities of 4 - 14 m/s. Ultimately, a deterrent as described here could provide a reliable, cost-effective means of alerting bats to the presence of moving turbine blades, reducing bat mortality at wind facilities, and reducing regulatory uncertainty for wind facility developers. The financial support provided by the US Department of Energy, and the Massachusetts Clean Energy center is acknowledged.

A Sensory-Motor Control Model of Animal Flight Explains Why Bats Fly Differently in Light Versus Dark

PubMed Central

Bar, Nadav S.; Skogestad, Sigurd; Marçal, Jose M.; Ulanovsky, Nachum; Yovel, Yossi

2015-01-01

Animal flight requires fine motor control. However, it is unknown how flying animals rapidly transform noisy sensory information into adequate motor commands. Here we developed a sensorimotor control model that explains vertebrate flight guidance with high fidelity. This simple model accurately reconstructed complex trajectories of bats flying in the dark. The model implies that in order to apply appropriate motor commands, bats have to estimate not only the angle-to-target, as was previously assumed, but also the angular velocity (“proportional-derivative” controller). Next, we conducted experiments in which bats flew in light conditions. When using vision, bats altered their movements, reducing the flight curvature. This change was explained by the model via reduction in sensory noise under vision versus pure echolocation. These results imply a surprising link between sensory noise and movement dynamics. We propose that this sensory-motor link is fundamental to motion control in rapidly moving animals under different sensory conditions, on land, sea, or air. PMID:25629809

Proceedings of the International Conference on Sensory Devices for the Blind (London, England, June, 1966).

ERIC Educational Resources Information Center

Dufton, Richard, Ed.

The conference proceedings include papers on sensory aids for visually handicapped mobility and reading. Two papers each treat mobility as a general problem, sociocultural surveys on mobility and reading, and echolocation in man and bats. Five papers concern reports and evaluations of practical trials of the sonic monaural aid; one deals with…

Descriptive analysis and comparison of strategic incremental rehearsal to "Business as Usual" sight-word instruction for an adult nonreader with intellectual disability.

PubMed

Richman, David M; Grubb, Laura; Thompson, Samuel

2018-01-01

Strategic Incremental Rehearsal (SIR) is an effective method for teaching sight-word acquisition, but has neither been evaluated for use in adults with an intellectual disability, nor directly compared to the ongoing instruction in the natural environment. Experimental analysis of sight word acquisition via an alternating treatment design was conducted with a 23-year-old woman with Down syndrome. SIR was compared to the current reading instruction (CRI) in a classroom for young adults with intellectual disabilities. CRI procedures included non-contingent praise, receptive touch prompts ("touch the word bat"), echoic prompts ("say bat"), textual prompts ("read the word"), and pre-determined introduction of new words. SIR procedures included textual prompts on flash cards, contingent praise, corrective feedback, and mastery-based introduction of new words. The results indicated that SIR was associated with more rapid acquisition of sight words than CRI. Directions for future research could include systematic comparisons to other procedures, and evaluations of procedural permutations of SIR.

Ultrasonic predator-prey interactions in water-convergent evolution with insects and bats in air?

PubMed

Wilson, Maria; Wahlberg, Magnus; Surlykke, Annemarie; Madsen, Peter Teglberg

2013-01-01

Toothed whales and bats have independently evolved biosonar systems to navigate and locate and catch prey. Such active sensing allows them to operate in darkness, but with the potential cost of warning prey by the emission of intense ultrasonic signals. At least six orders of nocturnal insects have independently evolved ears sensitive to ultrasound and exhibit evasive maneuvers when exposed to bat calls. Among aquatic prey on the other hand, the ability to detect and avoid ultrasound emitting predators seems to be limited to only one subfamily of Clupeidae: the Alosinae (shad and menhaden). These differences are likely rooted in the different physical properties of air and water where cuticular mechanoreceptors have been adapted to serve as ultrasound sensitive ears, whereas ultrasound detection in water have called for sensory cells mechanically connected to highly specialized gas volumes that can oscillate at high frequencies. In addition, there are most likely differences in the risk of predation between insects and fish from echolocating predators. The selection pressure among insects for evolving ultrasound sensitive ears is high, because essentially all nocturnal predation on flying insects stems from echolocating bats. In the interaction between toothed whales and their prey the selection pressure seems weaker, because toothed whales are by no means the only marine predators placing a selection pressure on their prey to evolve specific means to detect and avoid them. Toothed whales can generate extremely intense sound pressure levels, and it has been suggested that they may use these to debilitate prey. Recent experiments, however, show that neither fish with swim bladders, nor squid are debilitated by such signals. This strongly suggests that the production of high amplitude ultrasonic clicks serve the function of improving the detection range of the toothed whale biosonar system rather than debilitation of prey.

Effects of sound intensity on temporal properties of inhibition in the pallid bat auditory cortex.

PubMed

Razak, Khaleel A

2013-01-01

Auditory neurons in bats that use frequency modulated (FM) sweeps for echolocation are selective for the behaviorally-relevant rates and direction of frequency change. Such selectivity arises through spectrotemporal interactions between excitatory and inhibitory components of the receptive field. In the pallid bat auditory system, the relationship between FM sweep direction/rate selectivity and spectral and temporal properties of sideband inhibition have been characterized. Of note is the temporal asymmetry in sideband inhibition, with low-frequency inhibition (LFI) exhibiting faster arrival times compared to high-frequency inhibition (HFI). Using the two-tone inhibition over time (TTI) stimulus paradigm, this study investigated the interactions between two sound parameters in shaping sideband inhibition: intensity and time. Specifically, the impact of changing relative intensities of the excitatory and inhibitory tones on arrival time of inhibition was studied. Using this stimulation paradigm, single unit data from the auditory cortex of pentobarbital-anesthetized cortex show that the threshold for LFI is on average ~8 dB lower than HFI. For equal intensity tones near threshold, LFI is stronger than HFI. When the inhibitory tone intensity is increased further from threshold, the strength asymmetry decreased. The temporal asymmetry in LFI vs. HFI arrival time is strongest when the excitatory and inhibitory tones are of equal intensities or if excitatory tone is louder. As inhibitory tone intensity is increased, temporal asymmetry decreased suggesting that the relative magnitude of excitatory and inhibitory inputs shape arrival time of inhibition and FM sweep rate and direction selectivity. Given that most FM bats use downward sweeps as echolocation calls, a similar asymmetry in threshold and strength of LFI vs. HFI may be a general adaptation to enhance direction selectivity while maintaining sweep-rate selective responses to downward sweeps.

Unique Turbinal Morphology in Horseshoe Bats (Chiroptera: Rhinolophidae).

PubMed

Curtis, Abigail A; Simmons, Nancy B

2017-02-01

The mammalian nasal fossa contains a set of delicate and often structurally complex bones called turbinals. Turbinals and associated mucosae function in regulating respiratory heat and water loss, increasing surface area for olfactory tissue, and directing airflow within the nasal fossa. We used high-resolution micro-CT scanning to investigate a unique maxilloturbinal morphology in 37 species from the bat family Rhinolophidae, which we compared with those of families Hipposideridae, Megadermatidae, and Pteropodidae. Rhinolophids exhibit numerous structural modifications along the nasopharyngeal tract associated with emission of high duty cycle echolocation calls via the nostrils. In rhinolophids, we found that the maxilloturbinals and a portion of ethmoturbinal I form a pair of strand-like bony structures on each side of the nasal chamber. These structures project anteriorly from the transverse lamina and complete a hairpin turn to project posteriorly down the nasopharyngeal duct, and vary in length among species. The strand-like maxilloturbinals in Rhinolophidae were not observed in our outgroups and represent a synapomorphy for this family, and are unique in form among mammals. Within Rhinolophidae, maxilloturbinal size and cross-sectional shape were correlated with phylogeny. We hypothesize that strand-shaped maxilloturbinals may function to reduce respiratory heat and water loss without greatly impacting echolocation call transmission since they provide increased mucosal surface area for heat and moisture exchange but occupy minimal space. Alternatively, they may play a role in transmission of echolocation calls since they are located directly along the path sound travels between the larynx and nostrils during call emission. Anat Rec, 300:309-325, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Moth tails divert bat attack: evolution of acoustic deflection.

PubMed

Barber, Jesse R; Leavell, Brian C; Keener, Adam L; Breinholt, Jesse W; Chadwell, Brad A; McClure, Christopher J W; Hill, Geena M; Kawahara, Akito Y

2015-03-03

Adaptations to divert the attacks of visually guided predators have evolved repeatedly in animals. Using high-speed infrared videography, we show that luna moths (Actias luna) generate an acoustic diversion with spinning hindwing tails to deflect echolocating bat attacks away from their body and toward these nonessential appendages. We pit luna moths against big brown bats (Eptesicus fuscus) and demonstrate a survival advantage of ∼ 47% for moths with tails versus those that had their tails removed. The benefit of hindwing tails is equivalent to the advantage conferred to moths by bat-detecting ears. Moth tails lured bat attacks to these wing regions during 55% of interactions between bats and intact luna moths. We analyzed flight kinematics of moths with and without hindwing tails and suggest that tails have a minimal role in flight performance. Using a robust phylogeny, we find that long spatulate tails have independently evolved four times in saturniid moths, further supporting the selective advantage of this anti-bat strategy. Diversionary tactics are perhaps more common than appreciated in predator-prey interactions. Our finding suggests that focusing on the sensory ecologies of key predators will reveal such countermeasures in prey.

First encounter of European bat lyssavirus type 2 (EBLV-2) in a bat in Finland.

PubMed

Jakava-Viljanen, M; Lilley, T; Kyheröinen, E-M; Huovilainen, A

2010-11-01

In Finland, rabies in bats was suspected for the first time in 1985 when a bat researcher, who had multiple bat bites, died in Helsinki. The virus isolated from the researcher proved to be antigenically related to rabies viruses previously detected in German bats. Later, the virus was typed as EBLV-2b. Despite an epidemiological study in bats 1986 and subsequent rabies surveillance, rabies in bats was not detected in Finland until the first case in a Daubenton's bat (Myotis daubentonii) was confirmed in August 2009. The bat was paralysed, occasionally crying, and biting when approached; it subsequently tested positive for rabies. The virus was genetically typed as EBLV-2. This is the northernmost case of bat rabies ever detected in Europe. Phylogenetic analyses showed that the EBLV-2b isolate from the human case in 1985 and the isolate from the bat in 2009 were genetically closely related, demonstrating that EBLV-2 may have been circulating in Finland for many years.

Bat Biology, Genomes, and the Bat1K Project: To Generate Chromosome-Level Genomes for All Living Bat Species.

PubMed

Teeling, Emma C; Vernes, Sonja C; Dávalos, Liliana M; Ray, David A; Gilbert, M Thomas P; Myers, Eugene

2018-02-15

Bats are unique among mammals, possessing some of the rarest mammalian adaptations, including true self-powered flight, laryngeal echolocation, exceptional longevity, unique immunity, contracted genomes, and vocal learning. They provide key ecosystem services, pollinating tropical plants, dispersing seeds, and controlling insect pest populations, thus driving healthy ecosystems. They account for more than 20% of all living mammalian diversity, and their crown-group evolutionary history dates back to the Eocene. Despite their great numbers and diversity, many species are threatened and endangered. Here we announce Bat1K, an initiative to sequence the genomes of all living bat species (n∼1,300) to chromosome-level assembly. The Bat1K genome consortium unites bat biologists (>148 members as of writing), computational scientists, conservation organizations, genome technologists, and any interested individuals committed to a better understanding of the genetic and evolutionary mechanisms that underlie the unique adaptations of bats. Our aim is to catalog the unique genetic diversity present in all living bats to better understand the molecular basis of their unique adaptations; uncover their evolutionary history; link genotype with phenotype; and ultimately better understand, promote, and conserve bats. Here we review the unique adaptations of bats and highlight how chromosome-level genome assemblies can uncover the molecular basis of these traits. We present a novel sequencing and assembly strategy and review the striking societal and scientific benefits that will result from the Bat1K initiative.

Acoustic communication in plant-animal interactions.

PubMed

Schöner, Michael G; Simon, Ralph; Schöner, Caroline R

2016-08-01

Acoustic communication is widespread and well-studied in animals but has been neglected in other organisms such as plants. However, there is growing evidence for acoustic communication in plant-animal interactions. While knowledge about active acoustic signalling in plants (i.e. active sound production) is still in its infancy, research on passive acoustic signalling (i.e. reflection of animal sounds) revealed that bat-dependent plants have adapted to the bats' echolocation systems by providing acoustic reflectors to attract their animal partners. Understanding the proximate mechanisms and ultimate causes of acoustic communication will shed light on an underestimated dimension of information transfer between plants and animals. Copyright © 2016 Elsevier Ltd. All rights reserved.

Behavioral responses of big brown bats to dives by praying mantises

PubMed Central

Ghose, Kaushik; Triblehorn, Jeffrey D.; Bohn, Kari; Yager, David D.; Moss, Cynthia F.

2009-01-01

Summary Insectivorous echolocating bats face a formidable array of defenses employed by their airborne prey. One such insect defense is the ultrasound-triggered dive, which is a sudden, rapid drop in altitude, sometimes all the way to the ground. Although many previous studies have investigated the dynamics of such dives and their effect on insect survival rate, there has been little work on how bats may adapt to such an insect defense employed in the middle of pursuit. In this study we investigated how big brown bats (Eptesicus fuscus) adjust their pursuit strategy when flying praying mantises (Parasphendale agrionina) execute evasive, ultrasound-triggered dives. Although the mantis dive occasionally forced the bat to completely abort its chase (25% trials), in a number of cases (75% trials) the bat followed the mantis into the dive. In such cases the bat kept its sonar beam locked onto the target and maneuvered to maintain the same time efficient strategy it adopted during level flight pursuit, though it was ultimately defeated by the dive. This study suggests that although the mantis dive can be effective in evading the bat, it does not always deter the bat from continuing pursuit and, given enough altitude, the bat can potentially capture diving prey using the same flight strategy it employs to intercept prey in level flight. PMID:19218521

Effect of light intensity on food detection in captive great fruit-eating bats, Artibeus lituratus (Chiroptera: Phyllostomidae).

PubMed

Gutierrez, Eduardo de A; Pessoa, Valdir F; Aguiar, Ludmilla M S; Pessoa, Daniel M A

2014-11-01

Bats are known for their well-developed echolocation. However, several experiments focused on the bat visual system have shown evidence of the importance of visual cues under specific luminosity for different aspects of bat biology, including foraging behavior. This study examined the foraging abilities of five female great fruit-eating bats, Artibeus lituratus, under different light intensities. Animals were given a series of tasks to test for discrimination between a food target against an inedible background, under light levels similar to the twilight illumination (18lx), the full moon (2lx) and complete darkness (0lx). We found that the bats required a longer time frame to detect targets under a light intensity similar to twilight, possibly due to inhibitory effects present under a more intense light level. Additionally, bats were more efficient at detecting and capturing targets under light conditions similar to the luminosity of a full moon, suggesting that visual cues were important for target discrimination. These results demonstrate that light intensity affects foraging behavior and enables the use of visual cues for food detection in frugivorous bats. This article is part of a Special Issue entitled: Neotropical Behaviour. Copyright © 2014 Elsevier B.V. All rights reserved.

Relaxed evolution in the tyrosine aminotransferase gene tat in old world fruit bats (Chiroptera: Pteropodidae).

PubMed

Shen, Bin; Fang, Tao; Yang, Tianxiao; Jones, Gareth; Irwin, David M; Zhang, Shuyi

2014-01-01

Frugivorous and nectarivorous bats fuel their metabolism mostly by using carbohydrates and allocate the restricted amounts of ingested proteins mainly for anabolic protein syntheses rather than for catabolic energy production. Thus, it is possible that genes involved in protein (amino acid) catabolism may have undergone relaxed evolution in these fruit- and nectar-eating bats. The tyrosine aminotransferase (TAT, encoded by the Tat gene) is the rate-limiting enzyme in the tyrosine catabolic pathway. To test whether the Tat gene has undergone relaxed evolution in the fruit- and nectar-eating bats, we obtained the Tat coding region from 20 bat species including four Old World fruit bats (Pteropodidae) and two New World fruit bats (Phyllostomidae). Phylogenetic reconstructions revealed a gene tree in which all echolocating bats (including the New World fruit bats) formed a monophyletic group. The phylogenetic conflict appears to stem from accelerated TAT protein sequence evolution in the Old World fruit bats. Our molecular evolutionary analyses confirmed a change in the selection pressure acting on Tat, which was likely caused by a relaxation of the evolutionary constraints on the Tat gene in the Old World fruit bats. Hepatic TAT activity assays showed that TAT activities in species of the Old World fruit bats are significantly lower than those of insectivorous bats and omnivorous mice, which was not caused by a change in TAT protein levels in the liver. Our study provides unambiguous evidence that the Tat gene has undergone relaxed evolution in the Old World fruit bats in response to changes in their metabolism due to the evolution of their special diet.

Acoustic shadows help gleaning bats find prey, but may be defeated by prey acoustic camouflage on rough surfaces.

PubMed

Clare, Elizabeth L; Holderied, Marc W

2015-09-01

Perceptual abilities of animals, like echolocating bats, are difficult to study because they challenge our understanding of non-visual senses. We used novel acoustic tomography to convert echoes into visual representations and compare these cues to traditional echo measurements. We provide a new hypothesis for the echo-acoustic basis of prey detection on surfaces. We propose that bats perceive a change in depth profile and an 'acoustic shadow' cast by prey. The shadow is more salient than prey echoes and particularly strong on smooth surfaces. This may explain why bats look for prey on flat surfaces like leaves using scanning behaviour. We propose that rather than forming search images for prey, whose characteristics are unpredictable, predators may look for disruptions to the resting surface (acoustic shadows). The fact that the acoustic shadow is much fainter on rougher resting surfaces provides the first empirical evidence for 'acoustic camouflage' as an anti-predator defence mechanism.

Biological characters of bats in relation to natural reservoir of emerging viruses.

PubMed

Omatsu, Tsutomu; Watanabe, Shumpei; Akashi, Hiroomi; Yoshikawa, Yasuhiro

2007-09-01

Many investigators focused on bats (Chiroptera) for their specific character, i.e. echolocation system, phylogenic tree, food practice and unique reproduction. However, most of basic information about the vital functions related to anti-viral activity has been unclear. For evaluating some animals as a natural reservoir or host of infectious pathogens, it is necessary that not only their immune system but also their biology, the environment of their living, food habits and physiological features should be clarified and they should be analyzed from these multi-view points. The majority of current studies on infectious diseases have been conducted for the elucidation of viral virulence using experimental animals or viral gene function in vitro, but in a few case, researchers focused on wild animal itself. In this paper, we described basic information about bats as follows; genetic background, character of the immunological factors, histological character of immune organs, the physiological function and sensitivity of bat cells to viral infection.

The use of ultrasound for communication by the big brown bat (Eptesicus fuscus)

NASA Astrophysics Data System (ADS)

Grilliot, Matthew E.

2007-12-01

Communication signals are important regulators of mating behavior in many animals. Various pre- and post-copulatory mechanisms have been suggested to play a role in the reproductive success and mating strategies of many mammals. Recent studies have cited sperm competition as a possible post-copulatory mechanism of selection in bats, but few studies have examined which pre-copulatory mechanisms influence mate selection. Although it is generally accepted that bats emit vocalizations that function for communication purposes as well as the more universally recognized echolocation function, there is lack of actual empirical support for this idea. In this dissertation, I test the hypothesis that ultrasonic vocalizations of big brown bats are sexually dimorphic and differ contextually in the mating season. I used playback experiments to test the response of male and female big brown bats to variations in ultrasonic vocalizations of the opposite sex and to determine if ultrasonic vocalizations are used for mate selection. My data suggest that males were likely to select ultrasonic vocalization of frequently copulating females, but females did not select ultrasonic vocalizations of frequently copulating males over infrequently copulating males. These results suggest that mate selection of male big brown bats is influenced by ultrasonic vocalizations of females.

Mouth-clicks used by blind expert human echolocators - signal description and model based signal synthesis.

PubMed

Thaler, Lore; Reich, Galen M; Zhang, Xinyu; Wang, Dinghe; Smith, Graeme E; Tao, Zeng; Abdullah, Raja Syamsul Azmir Bin Raja; Cherniakov, Mikhail; Baker, Christopher J; Kish, Daniel; Antoniou, Michail

2017-08-01

Echolocation is the ability to use sound-echoes to infer spatial information about the environment. Some blind people have developed extraordinary proficiency in echolocation using mouth-clicks. The first step of human biosonar is the transmission (mouth click) and subsequent reception of the resultant sound through the ear. Existing head-related transfer function (HRTF) data bases provide descriptions of reception of the resultant sound. For the current report, we collected a large database of click emissions with three blind people expertly trained in echolocation, which allowed us to perform unprecedented analyses. Specifically, the current report provides the first ever description of the spatial distribution (i.e. beam pattern) of human expert echolocation transmissions, as well as spectro-temporal descriptions at a level of detail not available before. Our data show that transmission levels are fairly constant within a 60° cone emanating from the mouth, but levels drop gradually at further angles, more than for speech. In terms of spectro-temporal features, our data show that emissions are consistently very brief (~3ms duration) with peak frequencies 2-4kHz, but with energy also at 10kHz. This differs from previous reports of durations 3-15ms and peak frequencies 2-8kHz, which were based on less detailed measurements. Based on our measurements we propose to model transmissions as sum of monotones modulated by a decaying exponential, with angular attenuation by a modified cardioid. We provide model parameters for each echolocator. These results are a step towards developing computational models of human biosonar. For example, in bats, spatial and spectro-temporal features of emissions have been used to derive and test model based hypotheses about behaviour. The data we present here suggest similar research opportunities within the context of human echolocation. Relatedly, the data are a basis to develop synthetic models of human echolocation that could be virtual (i.e. simulated) or real (i.e. loudspeaker, microphones), and which will help understanding the link between physical principles and human behaviour.

Mouth-clicks used by blind expert human echolocators – signal description and model based signal synthesis

PubMed Central

Zhang, Xinyu; Wang, Dinghe; Tao, Zeng; Abdullah, Raja Syamsul Azmir Bin. Raja; Cherniakov, Mikhail; Kish, Daniel

2017-01-01

Echolocation is the ability to use sound-echoes to infer spatial information about the environment. Some blind people have developed extraordinary proficiency in echolocation using mouth-clicks. The first step of human biosonar is the transmission (mouth click) and subsequent reception of the resultant sound through the ear. Existing head-related transfer function (HRTF) data bases provide descriptions of reception of the resultant sound. For the current report, we collected a large database of click emissions with three blind people expertly trained in echolocation, which allowed us to perform unprecedented analyses. Specifically, the current report provides the first ever description of the spatial distribution (i.e. beam pattern) of human expert echolocation transmissions, as well as spectro-temporal descriptions at a level of detail not available before. Our data show that transmission levels are fairly constant within a 60° cone emanating from the mouth, but levels drop gradually at further angles, more than for speech. In terms of spectro-temporal features, our data show that emissions are consistently very brief (~3ms duration) with peak frequencies 2-4kHz, but with energy also at 10kHz. This differs from previous reports of durations 3-15ms and peak frequencies 2-8kHz, which were based on less detailed measurements. Based on our measurements we propose to model transmissions as sum of monotones modulated by a decaying exponential, with angular attenuation by a modified cardioid. We provide model parameters for each echolocator. These results are a step towards developing computational models of human biosonar. For example, in bats, spatial and spectro-temporal features of emissions have been used to derive and test model based hypotheses about behaviour. The data we present here suggest similar research opportunities within the context of human echolocation. Relatedly, the data are a basis to develop synthetic models of human echolocation that could be virtual (i.e. simulated) or real (i.e. loudspeaker, microphones), and which will help understanding the link between physical principles and human behaviour. PMID:28859082

Biosonar performance of foraging beaked whales (Mesoplodon densirostris).

PubMed

Madsen, P T; Johnson, M; de Soto, N Aguilar; Zimmer, W M X; Tyack, P

2005-01-01

Toothed whales (Cetacea, odontoceti) emit sound pulses to probe their surroundings by active echolocation. Non-invasive, acoustic Dtags were placed on deep-diving Blainville's beaked whales (Mesoplodon densirostris) to record their ultrasonic clicks and the returning echoes from prey items, providing a unique view on how a whale operates its biosonar during foraging in the wild. The process of echolocation during prey capture in this species can be divided into search, approach and terminal phases, as in echolocating bats. The approach phase, defined by the onset of detectable echoes recorded on the tag for click sequences terminated by a buzz, has interclick intervals (ICI) of 300-400 ms. These ICIs are more than a magnitude longer than the decreasing two-way travel time to the targets, showing that ICIs are not given by the two-way-travel times plus a fixed, short lag time. During the approach phase, the received echo energy increases by 10.4(+/-2) dB when the target range is halved, demonstrating that the whales do not employ range-compensating gain control of the transmitter, as has been implicated for some bats and dolphins. The terminal/buzz phase with ICIs of around 10 ms is initiated when one or more targets are within approximately a body length of the whale (2-5 m), so that strong echo returns in the approach phase are traded for rapid updates in the terminal phase. It is suggested that stable ICIs in the search and approach phases facilitate auditory scene analysis in a complex multi-target environment, and that a concomitant low click rate allows the whales to maintain high sound pressure outputs for prey detection and discrimination with a pneumatically driven, bi-modal sound generator.

Genome-wide signatures of convergent evolution in echolocating mammals

PubMed Central

Parker, Joe; Tsagkogeorga, Georgia; Cotton, James A.; Liu, Yuan; Provero, Paolo; Stupka, Elia; Rossiter, Stephen J.

2013-01-01

Evolution is typically thought to proceed through divergence of genes, proteins, and ultimately phenotypes1-3. However, similar traits might also evolve convergently in unrelated taxa due to similar selection pressures4,5. Adaptive phenotypic convergence is widespread in nature, and recent results from a handful of genes have suggested that this phenomenon is powerful enough to also drive recurrent evolution at the sequence level6-9. Where homoplasious substitutions do occur these have long been considered the result of neutral processes. However, recent studies have demonstrated that adaptive convergent sequence evolution can be detected in vertebrates using statistical methods that model parallel evolution9,10 although the extent to which sequence convergence between genera occurs across genomes is unknown. Here we analyse genomic sequence data in mammals that have independently evolved echolocation and show for the first time that convergence is not a rare process restricted to a handful of loci but is instead widespread, continuously distributed and commonly driven by natural selection acting on a small number of sites per locus. Systematic analyses of convergent sequence evolution in 805,053 amino acids within 2,326 orthologous coding gene sequences compared across 22 mammals (including four new bat genomes) revealed signatures consistent with convergence in nearly 200 loci. Strong and significant support for convergence among bats and the dolphin was seen in numerous genes linked to hearing or deafness, consistent with an involvement in echolocation. Surprisingly we also found convergence in many genes linked to vision: the convergent signal of many sensory genes was robustly correlated with the strength of natural selection. This first attempt to detect genome-wide convergent sequence evolution across divergent taxa reveals the phenomenon to be much more pervasive than previously recognised. PMID:24005325

Bats of Mesa Verde National Park, Colorado: composition, reproduction, and roosting habits.

USGS Publications Warehouse

O'Shea, Thomas J.; Cryan, Paul M.; Snider, E. Apple; Valdez, Ernest W.; Ellison, Laura E.; Neubaum, Daniel J.

2011-01-01

We determined the bat fauna at Mesa Verde National Park (Mesa Verde) in 2006 and 2007, characterized bat elevational distribution and reproduction, and investigated roosting habits of selected species. We captured 1996 bats of 15 species in mist nets set over water during 120 nights of sampling and recorded echolocation calls of an additional species. The bat fauna at Mesa Verde included every species of bat known west of the Great Plains in Colorado, except the little brown bat (Myotis lucifugus). Some species showed skewed sex ratios, primarily due to a preponderance of males. Thirteen species of bats reproduced at Mesa Verde. Major differences in spring precipitation between the 2 years of our study were associated with differences in reproductive rates and, in some species, with numbers of juveniles captured. Reduced reproductive effort during spring drought will have a greater impact on bat populations with the forecasted increase in aridity in much of western North America by models of global climate change. We radiotracked 46 bats of 5 species to roosts and describe the first-known maternity colonies of spotted bats (Euderma maculatum) in Colorado. All 5 species that we tracked to diurnal roosts relied almost exclusively on rock crevices rather than trees or snags, despite the presence of mature forests at Mesa Verde and the use of trees for roosts in similar forests elsewhere by some of these species. Comparisons with past bat surveys at Mesa Verde and in surrounding areas suggest no dramatic evidence for effects of recent stand-replacing fires on the composition of the bat community.

Echo-level compensation and delay tuning in the auditory cortex of the mustached bat.

PubMed

Macías, Silvio; Mora, Emanuel C; Hechavarría, Julio C; Kössl, Manfred

2016-06-01

During echolocation, bats continuously perform audio-motor adjustments to optimize detection efficiency. It has been demonstrated that bats adjust the amplitude of their biosonar vocalizations (known as 'pulses') to stabilize the amplitude of the returning echo. Here, we investigated this echo-level compensation behaviour by swinging mustached bats on a pendulum towards a reflective surface. In such a situation, the bats lower the amplitude of their emitted pulses to maintain the amplitude of incoming echoes at a constant level as they approach a target. We report that cortical auditory neurons that encode target distance have receptive fields that are optimized for dealing with echo-level compensation. In most cortical delay-tuned neurons, the echo amplitude eliciting the maximum response matches the echo amplitudes measured from the bats' biosonar vocalizations while they are swung in a pendulum. In addition, neurons tuned to short target distances are maximally responsive to low pulse amplitudes while neurons tuned to long target distances respond maximally to high pulse amplitudes. Our results suggest that bats dynamically adjust biosonar pulse amplitude to match the encoding of target range and to keep the amplitude of the returning echo within the bounds of the cortical map of echo delays. © 2016 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Ear-body lift and a novel thrust generating mechanism revealed by the complex wake of brown long-eared bats (Plecotus auritus)

NASA Astrophysics Data System (ADS)

Johansson, L. Christoffer; Håkansson, Jonas; Jakobsen, Lasse; Hedenström, Anders

2016-04-01

Large ears enhance perception of echolocation and prey generated sounds in bats. However, external ears likely impair aerodynamic performance of bats compared to birds. But large ears may generate lift on their own, mitigating the negative effects. We studied flying brown long-eared bats, using high resolution, time resolved particle image velocimetry, to determine the aerodynamics of flying with large ears. We show that the ears and body generate lift at medium to cruising speeds (3-5 m/s), but at the cost of an interaction with the wing root vortices, likely reducing inner wing performance. We also propose that the bats use a novel wing pitch mechanism at the end of the upstroke generating thrust at low speeds, which should provide effective pitch and yaw control. In addition, the wing tip vortices show a distinct spiraling pattern. The tip vortex of the previous wingbeat remains into the next wingbeat and rotates together with a newly formed tip vortex. Several smaller vortices, related to changes in circulation around the wing also spiral the tip vortex. Our results thus show a new level of complexity in bat wakes and suggest large eared bats are less aerodynamically limited than previous wake studies have suggested.

Situational and Age-Dependent Decision Making during Life Threatening Distress in Myotis macrodactylus.

PubMed

Huang, Xiaobin; Kanwal, Jagmeet S; Jiang, Tinglei; Long, Zhenyu; Luo, Bo; Yue, Xinke; Gu, Yongbo; Feng, Jiang

2015-01-01

Echolocation and audiovocal communication have been studied extensively in bats. The manner in which these abilities are incorporated within escape behaviors during life-threatening distress is largely unknown. Here we tested the hypothesis that behavioral response profiles expressed during distress are relatively stereotypic given their evolutionary adaptations to avoid predators. We subjected juvenile and adult big-footed myotis (Myotis macrodactylus) to a sequence of three types of life threatening distress: 1) trapping them in a mist-net (environmental threat), 2) approaching them when trapped (predator threat), and 3) partially restraining their freedom to move (arrest), and recorded their escape behavior in each of the three conditions. Response profiles differed across individuals and with the context in which they were expressed. During environmental and predator threat, bats displayed significantly more biting and wing-flapping behaviors and emitted more echolocation pulses than during arrest. Response profiles also varied with age. During arrest, juveniles were more likely than adults to emit distress calls and vice-versa for biting and wing flapping during environmental and predator threat. Overall, individualized response profiles were classified into ten clusters that were aligned along two divergent response trajectories when viewed within two-dimensional, multifactorial decision space. Juvenile behaviors tended to follow a predominantly "social-dependence" trajectory, whereas adult behaviors were mostly aligned along a "self-reliance" trajectory. We conclude that bats modify their vocal behavior and make age-appropriate and contextually adaptive decisions when distressed. This decision-making ability is consistent with observations in other social species, including humans.

Situational and Age-Dependent Decision Making during Life Threatening Distress in Myotis macrodactylus

PubMed Central

Huang, Xiaobin; Kanwal, Jagmeet S.; Jiang, Tinglei; Long, Zhenyu; Luo, Bo; Yue, Xinke; Gu, Yongbo; Feng, Jiang

2015-01-01

Echolocation and audiovocal communication have been studied extensively in bats. The manner in which these abilities are incorporated within escape behaviors during life-threatening distress is largely unknown. Here we tested the hypothesis that behavioral response profiles expressed during distress are relatively stereotypic given their evolutionary adaptations to avoid predators. We subjected juvenile and adult big-footed myotis (Myotis macrodactylus) to a sequence of three types of life threatening distress: 1) trapping them in a mist-net (environmental threat), 2) approaching them when trapped (predator threat), and 3) partially restraining their freedom to move (arrest), and recorded their escape behavior in each of the three conditions. Response profiles differed across individuals and with the context in which they were expressed. During environmental and predator threat, bats displayed significantly more biting and wing-flapping behaviors and emitted more echolocation pulses than during arrest. Response profiles also varied with age. During arrest, juveniles were more likely than adults to emit distress calls and vice-versa for biting and wing flapping during environmental and predator threat. Overall, individualized response profiles were classified into ten clusters that were aligned along two divergent response trajectories when viewed within two-dimensional, multifactorial decision space. Juvenile behaviors tended to follow a predominantly “social-dependence” trajectory, whereas adult behaviors were mostly aligned along a “self-reliance” trajectory. We conclude that bats modify their vocal behavior and make age-appropriate and contextually adaptive decisions when distressed. This decision-making ability is consistent with observations in other social species, including humans. PMID:26181328

Do Bat Gantries and Underpasses Help Bats Cross Roads Safely?

PubMed Central

Berthinussen, Anna; Altringham, John

2012-01-01

Major roads can reduce bat abundance and diversity over considerable distances. To mitigate against these effects and comply with environmental law, many European countries install bridges, gantries or underpasses to make roads permeable and safer to cross. However, through lack of appropriate monitoring, there is little evidence to support their effectiveness. Three underpasses and four bat gantries were investigated in northern England. Echolocation call recordings and observations were used to determine the number of bats using underpasses in preference to crossing the road above, and the height at which bats crossed. At gantries, proximity to the gantry and height of crossing bats were measured. Data were compared to those from adjacent, severed commuting routes that had no crossing structure. At one underpass 96% of bats flew through it in preference to crossing the road. This underpass was located on a pre-construction commuting route that allowed bats to pass without changing flight height or direction. At two underpasses attempts to divert bats from their original commuting routes were unsuccessful and bats crossed the road at the height of passing vehicles. Underpasses have the potential to allow bats to cross roads safely if built on pre-construction commuting routes. Bat gantries were ineffective and used by a very small proportion of bats, even up to nine years after construction. Most bats near gantries crossed roads along severed, pre-construction commuting routes at heights that put them in the path of vehicles. Crossing height was strongly correlated with verge height, suggesting that elevated verges may have some value in mitigation, but increased flight height may be at the cost of reduced permeability. Green bridges should be explored as an alternative form of mitigation. Robust monitoring is essential to assess objectively the case for mitigation and to ensure effective mitigation. PMID:22719941

Clicking in a Killer Whale Habitat: Narrow-Band, High-Frequency Biosonar Clicks of Harbour Porpoise (Phocoena phocoena) and Dall’s Porpoise (Phocoenoides dalli)

PubMed Central

Kyhn, Line A.; Tougaard, Jakob; Beedholm, Kristian; Jensen, Frants H.; Ashe, Erin; Williams, Rob; Madsen, Peter T.

2013-01-01

Odontocetes produce a range of different echolocation clicks but four groups in different families have converged on producing the same stereotyped narrow band high frequency (NBHF) click. In microchiropteran bats, sympatric species have evolved the use of different acoustic niches and subtly different echolocation signals to avoid competition among species. In this study, we examined whether similar adaptations are at play among sympatric porpoise species that use NBHF echolocation clicks. We used a six-element hydrophone array to record harbour and Dall’s porpoises in British Columbia (BC), Canada, and harbour porpoises in Denmark. The click source properties of all porpoise groups were remarkably similar and had an average directivity index of 25 dB. Yet there was a small, but consistent and significant 4 kHz difference in centroid frequency between sympatric Dall’s (137±3 kHz) and Canadian harbour porpoises (141±2 kHz). Danish harbour porpoise clicks (136±3 kHz) were more similar to Dall’s porpoise than to their conspecifics in Canada. We suggest that the spectral differences in echolocation clicks between the sympatric porpoises are consistent with evolution of a prezygotic isolating barrier (i.e., character displacement) to avoid hybridization of sympatric species. In practical terms, these spectral differences have immediate application to passive acoustic monitoring. PMID:23723996

Clicking in a killer whale habitat: narrow-band, high-frequency biosonar clicks of harbour porpoise (Phocoena phocoena) and Dall's porpoise (Phocoenoides dalli).

PubMed

Kyhn, Line A; Tougaard, Jakob; Beedholm, Kristian; Jensen, Frants H; Ashe, Erin; Williams, Rob; Madsen, Peter T

2013-01-01

Odontocetes produce a range of different echolocation clicks but four groups in different families have converged on producing the same stereotyped narrow band high frequency (NBHF) click. In microchiropteran bats, sympatric species have evolved the use of different acoustic niches and subtly different echolocation signals to avoid competition among species. In this study, we examined whether similar adaptations are at play among sympatric porpoise species that use NBHF echolocation clicks. We used a six-element hydrophone array to record harbour and Dall's porpoises in British Columbia (BC), Canada, and harbour porpoises in Denmark. The click source properties of all porpoise groups were remarkably similar and had an average directivity index of 25 dB. Yet there was a small, but consistent and significant 4 kHz difference in centroid frequency between sympatric Dall's (137±3 kHz) and Canadian harbour porpoises (141±2 kHz). Danish harbour porpoise clicks (136±3 kHz) were more similar to Dall's porpoise than to their conspecifics in Canada. We suggest that the spectral differences in echolocation clicks between the sympatric porpoises are consistent with evolution of a prezygotic isolating barrier (i.e., character displacement) to avoid hybridization of sympatric species. In practical terms, these spectral differences have immediate application to passive acoustic monitoring.

Building a Virtual Model of a Baleen Whale: Phase 2

DTIC Science & Technology

2015-09-30

example, the biosonar signal generation mechanism and the formation of an acoustic transmission beam, or to measure the amplitude differences and...from simulations with published results from live animal biosonar research (Cranford and Krysl, 2013). Collectively, our research results butress the...2004). " Biosonar pulse production in odontocetes: The state of our knowledge," in Echolocation in bats and dolphins, edited by J. A. Thomas, C. F

Control of Biosonar Behavior by the Auditory Cortex

DTIC Science & Technology

1988-11-28

TITLE (include Security Classification) Control of Biosonar Behavior by the Auditory Cortex 12. PERSONAL AUTHOR(S) Nobuo Suga and Stephen Gaioni 13a...NOTATION 17. COSATI CODES IS SUBJECT TERMS (Continue on reverse if necessary and identify by block number) FIELD GROUP1 SUB-GROUP - biosonar ; echolocation...SLesion experiments were conducted to examine whether the functional organization of the mustached bat’s auditory cortex is related to biosonar

Building a Virtual Model of a Baleen Whale: Phase 2

DTIC Science & Technology

2013-09-30

valid by comparing results gleaned from live animals involved in biosonar tasks (Cranford and Krysl, 2013) and have begun the process of...Cranford, T. W., and Amundin, M. E. (2003). " Biosonar pulse production in odontocetes: The state of our knowledge," in Echolocation in bats and...Krysl, P. (2014). "Validation of a vibroacoustic finite element model using bottlenose dolphin simulations: The dolphin biosonar beam is focused in

Horseshoe bats make adaptive prey-selection decisions, informed by echo cues

PubMed Central

Koselj, Klemen; Schnitzler, Hans-Ulrich; Siemers, Björn M.

2011-01-01

Foragers base their prey-selection decisions on the information acquired by the sensory systems. In bats that use echolocation to find prey in darkness, it is not clear whether the specialized diet, as sometimes found by faecal analysis, is a result of active decision-making or rather of biased sensory information. Here, we tested whether greater horseshoe bats decide economically when to attack a particular prey item and when not. This species is known to recognize different insects based on their wing-beat pattern imprinted in the echoes. We built a simulation of the natural foraging process in the laboratory, where the bats scanned for prey from a perch and, upon reaching the decision to attack, intercepted the prey in flight. To fully control echo information available to the bats and assure its unambiguity, we implemented computer-controlled propellers that produced echoes resembling those from natural insects of differing profitability. The bats monitored prey arrivals to sample the supply of prey categories in the environment and to inform foraging decisions. The bats adjusted selectivity for the more profitable prey to its inter-arrival intervals as predicted by foraging theory (an economic strategy known to benefit fitness). Moreover, unlike in previously studied vertebrates, foraging performance of horseshoe bats was not limited by costly rejections of the profitable prey. This calls for further research into the evolutionary selection pressures that sharpened the species's decision-making capacity. PMID:21367788

Acoustic divergence in two cryptic Hipposideros species: a role for social selection?

PubMed Central

Kingston, T.; Lara, M. C.; Jones, G.; Akbar, Z.; Kunz, T. H.; Schneider, C. J.

2001-01-01

We present evidence that a relatively widespread and common bat from South East Asia comprises two morphologically cryptic but acoustically divergent species. A population of the bicoloured leaf-nosed bat (Hipposideros bicolor) from Peninsular Malaysia exhibits a bimodal distribution of echolocation call frequencies, with peaks in the frequency of maximum energy at ca. 131 and 142 kHz. The two phonic types are genetically distinct, with a cytochrome b sequence divergence of just under 7%. We consider the mechanisms by which acoustic divergence in these species might arise. Differences in call frequency are not likely to effect resource partitioning by detectable prey size or functional range. However, ecological segregation may be achieved by differences in microhabitat use; the 131kHz H. bicolor is characterized by significantly longer forearms, lower wing loading, a lower aspect ratio and a more rounded wingtip, features that are associated with greater manoeuvrability in flight that may enable it to forage in more cluttered environments relative to the 142 kHz phonic type. We suggest that acoustic divergence in these species is a consequence of social selection for a clear communication channel, which is mediated by the close link between the acoustic signal and receptor systems imposed by the highly specialized nature of the hipposiderid and rhinolophid echolocation system. PMID:11429138

Relaxed Evolution in the Tyrosine Aminotransferase Gene Tat in Old World Fruit Bats (Chiroptera: Pteropodidae)

PubMed Central

Shen, Bin; Fang, Tao; Yang, Tianxiao; Jones, Gareth; Irwin, David M.; Zhang, Shuyi

2014-01-01

Frugivorous and nectarivorous bats fuel their metabolism mostly by using carbohydrates and allocate the restricted amounts of ingested proteins mainly for anabolic protein syntheses rather than for catabolic energy production. Thus, it is possible that genes involved in protein (amino acid) catabolism may have undergone relaxed evolution in these fruit- and nectar-eating bats. The tyrosine aminotransferase (TAT, encoded by the Tat gene) is the rate-limiting enzyme in the tyrosine catabolic pathway. To test whether the Tat gene has undergone relaxed evolution in the fruit- and nectar-eating bats, we obtained the Tat coding region from 20 bat species including four Old World fruit bats (Pteropodidae) and two New World fruit bats (Phyllostomidae). Phylogenetic reconstructions revealed a gene tree in which all echolocating bats (including the New World fruit bats) formed a monophyletic group. The phylogenetic conflict appears to stem from accelerated TAT protein sequence evolution in the Old World fruit bats. Our molecular evolutionary analyses confirmed a change in the selection pressure acting on Tat, which was likely caused by a relaxation of the evolutionary constraints on the Tat gene in the Old World fruit bats. Hepatic TAT activity assays showed that TAT activities in species of the Old World fruit bats are significantly lower than those of insectivorous bats and omnivorous mice, which was not caused by a change in TAT protein levels in the liver. Our study provides unambiguous evidence that the Tat gene has undergone relaxed evolution in the Old World fruit bats in response to changes in their metabolism due to the evolution of their special diet. PMID:24824435

Ultrasonic predator–prey interactions in water–convergent evolution with insects and bats in air?

PubMed Central

Wilson, Maria; Wahlberg, Magnus; Surlykke, Annemarie; Madsen, Peter Teglberg

2013-01-01

Toothed whales and bats have independently evolved biosonar systems to navigate and locate and catch prey. Such active sensing allows them to operate in darkness, but with the potential cost of warning prey by the emission of intense ultrasonic signals. At least six orders of nocturnal insects have independently evolved ears sensitive to ultrasound and exhibit evasive maneuvers when exposed to bat calls. Among aquatic prey on the other hand, the ability to detect and avoid ultrasound emitting predators seems to be limited to only one subfamily of Clupeidae: the Alosinae (shad and menhaden). These differences are likely rooted in the different physical properties of air and water where cuticular mechanoreceptors have been adapted to serve as ultrasound sensitive ears, whereas ultrasound detection in water have called for sensory cells mechanically connected to highly specialized gas volumes that can oscillate at high frequencies. In addition, there are most likely differences in the risk of predation between insects and fish from echolocating predators. The selection pressure among insects for evolving ultrasound sensitive ears is high, because essentially all nocturnal predation on flying insects stems from echolocating bats. In the interaction between toothed whales and their prey the selection pressure seems weaker, because toothed whales are by no means the only marine predators placing a selection pressure on their prey to evolve specific means to detect and avoid them. Toothed whales can generate extremely intense sound pressure levels, and it has been suggested that they may use these to debilitate prey. Recent experiments, however, show that neither fish with swim bladders, nor squid are debilitated by such signals. This strongly suggests that the production of high amplitude ultrasonic clicks serve the function of improving the detection range of the toothed whale biosonar system rather than debilitation of prey. PMID:23781206

Hippocampal neurogenesis and cortical cellular plasticity in Wahlberg's epauletted fruit bat: a qualitative and quantitative study.

PubMed

Gatome, Catherine W; Mwangi, Deter K; Lipp, Hans-Peter; Amrein, Irmgard

2010-01-01

Species-specific characteristics of neuronal plasticity emerging from comparative studies can address the functional relevance of hippocampal or cortical plasticity in the light of ecological adaptation and evolutionary history of a given species. Here, we present a quantitative and qualitative analysis of neurogenesis in young and adult free-living Wahlberg's epauletted fruit bats. Using the markers for proliferating cell nuclear antigen (PCNA), bromodeoxyuridine (BrdU), doublecortin (DCX) and polysialic acid neural cell adhesion molecule (PSA-NCAM), our findings in the hippocampus, olfactory bulb and cortical regions are described and compared to reports in other mammals. Expressed as a percentage of the total number of granule cells, PCNA- and BrdU-positive cells accounted for 0.04 in young to 0.01% in adult animals; DCX-positive cells for 0.05 (young) to 0.01% (adult); PSA-NCAM-positive cells for 0.1 (young) to 0.02% (adult), and pyknotic cells for 0.007 (young) to 0.005% (adult). The numbers were comparable to other long-lived, late-maturing mammals such as primates. A significant increase in the total granule cell number from young to adult animals demonstrated the successful formation and integration of new cells. In adulthood, granule cell number appeared stable and was surprisingly low in comparison to other species. Observations in the olfactory bulb and rostral migratory stream were qualitatively similar to descriptions in other species. In the ventral horn of the lateral ventricle, we noted prominent expression of DCX and PSA-NCAM forming a temporal migratory stream targeting the piriform cortex, possibly reflecting the importance of olfaction to these species. Low, but persistent hippocampal neurogenesis in non-echolocating fruit bats contrasted the findings in echolocating microbats, in which hippocampal neurogenesis was largely absent. Together with the observed intense cortical plasticity in the olfactory system of fruit bats we suggest a differential influence of sensory modalities on hippocampal and cortical plasticity in this mammalian order. Copyright © 2010 S. Karger AG, Basel.

Entropy analysis of frequency and shape change in horseshoe bat biosonar

NASA Astrophysics Data System (ADS)

Gupta, Anupam K.; Webster, Dane; Müller, Rolf

2018-06-01

Echolocating bats use ultrasonic pulses to collect information about their environments. Some of this information is encoded at the baffle structures—noseleaves (emission) and pinnae (reception)—that act as interfaces between the bats' biosonar systems and the external world. The baffle beam patterns encode the direction-dependent sensory information as a function of frequency and hence represent a view of the environment. To generate diverse views of the environment, the bats can vary beam patterns by changes to (1) the wavelengths of the pulses or (2) the baffle geometries. Here we compare the variability in sensory information encoded by just the use of frequency or baffle shape dynamics in horseshoe bats. For this, we use digital and physical prototypes of both noseleaf and pinnae. The beam patterns for all prototypes were either measured or numerically predicted. Entropy was used as a measure to compare variability as a measure of sensory information encoding capacity. It was found that new information was acquired as a result of shape dynamics. Furthermore, the overall variability available for information encoding was similar in the case of frequency or shape dynamics. Thus, shape dynamics allows the horseshoe bats to generate diverse views of the environment in the absence of broadband biosonar signals.

Evolution of the heteroharmonic strategy for target-range computation in the echolocation of Mormoopidae

PubMed Central

Mora, Emanuel C.; Macías, Silvio; Hechavarría, Julio; Vater, Marianne; Kössl, Manfred

2013-01-01

Echolocating bats use the time elapsed from biosonar pulse emission to the arrival of echo (defined as echo-delay) to assess target-distance. Target-distance is represented in the brain by delay-tuned neurons that are classified as either “heteroharmonic” or “homoharmormic.” Heteroharmonic neurons respond more strongly to pulse-echo pairs in which the timing of the pulse is given by the fundamental biosonar harmonic while the timing of echoes is provided by one (or several) of the higher order harmonics. On the other hand, homoharmonic neurons are tuned to the echo delay between similar harmonics in the emitted pulse and echo. It is generally accepted that heteroharmonic computations are advantageous over homoharmonic computations; i.e., heteroharmonic neurons receive information from call and echo in different frequency-bands which helps to avoid jamming between pulse and echo signals. Heteroharmonic neurons have been found in two species of the family Mormoopidae (Pteronotus parnellii and Pteronotus quadridens) and in Rhinolophus rouxi. Recently, it was proposed that heteroharmonic target-range computations are a primitive feature of the genus Pteronotus that was preserved in the evolution of the genus. Here, we review recent findings on the evolution of echolocation in Mormoopidae, and try to link those findings to the evolution of the heteroharmonic computation strategy (HtHCS). We stress the hypothesis that the ability to perform heteroharmonic computations evolved separately from the ability of using long constant-frequency echolocation calls, high duty cycle echolocation, and Doppler Shift Compensation. Also, we present the idea that heteroharmonic computations might have been of advantage for categorizing prey size, hunting eared insects, and living in large conspecific colonies. We make five testable predictions that might help future investigations to clarify the evolution of the heteroharmonic echolocation in Mormoopidae and other families. PMID:23781209

Effects of selective logging on bat communities in the southeastern Amazon.

PubMed

Peters, Sandra L; Malcolm, Jay R; Zimmerman, Barbara L

2006-10-01

Although extensive areas of tropical forest are selectively logged each year, the responses of bat communities to this form of disturbance have rarely been examined. Our objectives were to (1) compare bat abundance, species composition, and feeding guild structure between unlogged and low-intensity selectively logged (1-4 logged stems/ha) sampling grids in the southeastern Amazon and (2) examine correlations between logging-induced changes in bat communities and forest structure. We captured bats in understory and canopy mist nets set in five 1-ha study grids in both logged and unlogged forest. We captured 996 individuals, representing 5 families, 32 genera, and 49 species. Abundances of nectarivorous and frugivorous taxa (Glossophaginae, Lonchophyllinae, Stenodermatinae, and Carolliinae) were higher at logged sites, where canopy openness and understory foliage density were greatest. In contrast, insectivorous and omnivorous species (Emballonuridae, Mormoopidae, Phyllostominae, and Vespertilionidae) were more abundant in unlogged sites, where canopy foliage density and variability in the understory stratum were greatest. Multivariate analyses indicated that understory bat species composition differed strongly between logged and unlogged sites but provided little evidence of logging effects for the canopy fauna. Different responses among feeding guilds and taxonomic groups appeared to be related to foraging and echolocation strategies and to changes in canopy cover and understory foliage densities. Our results suggest that even low-intensity logging modifies habitat structure, leading to changes in bat species composition.

Plant Classification from Bat-Like Echolocation Signals

PubMed Central

Yovel, Yossi; Franz, Matthias Otto; Stilz, Peter; Schnitzler, Hans-Ulrich

2008-01-01

Classification of plants according to their echoes is an elementary component of bat behavior that plays an important role in spatial orientation and food acquisition. Vegetation echoes are, however, highly complex stochastic signals: from an acoustical point of view, a plant can be thought of as a three-dimensional array of leaves reflecting the emitted bat call. The received echo is therefore a superposition of many reflections. In this work we suggest that the classification of these echoes might not be such a troublesome routine for bats as formerly thought. We present a rather simple approach to classifying signals from a large database of plant echoes that were created by ensonifying plants with a frequency-modulated bat-like ultrasonic pulse. Our algorithm uses the spectrogram of a single echo from which it only uses features that are undoubtedly accessible to bats. We used a standard machine learning algorithm (SVM) to automatically extract suitable linear combinations of time and frequency cues from the spectrograms such that classification with high accuracy is enabled. This demonstrates that ultrasonic echoes are highly informative about the species membership of an ensonified plant, and that this information can be extracted with rather simple, biologically plausible analysis. Thus, our findings provide a new explanatory basis for the poorly understood observed abilities of bats in classifying vegetation and other complex objects. PMID:18369425

Development of a frequency-modulated ultrasonic sensor inspired by bat echolocation

NASA Astrophysics Data System (ADS)

Kepa, Krzysztof; Abaid, Nicole

2015-03-01

Bats have evolved to sense using ultrasonic signals with a variety of different frequency signatures which interact with their environment. Among these signals, those with time-varying frequencies may enable the animals to gather more complex information for obstacle avoidance and target tracking. Taking inspiration from this system, we present the development of a sonar sensor capable of generating frequency-modulated ultrasonic signals. The device is based on a miniature mobile computer, with on board data capture and processing capabilities, which is designed for eventual autonomous operation in a robotic swarm. The hardware and software components of the sensor are detailed, as well their integration. Preliminary results for target detection using both frequency-modulated and constant frequency signals are discussed.

Advances on molecular mechanism of the adaptive evolution of Chiroptera (bats).

PubMed

Yunpeng, Liang; Li, Yu

2015-01-01

As the second biggest animal group in mammals, Chiroptera (bats) demonstrates many unique adaptive features in terms of flight, echolocation, auditory acuity, feeding habit, hibernation and immune defense, providing an excellent system for understanding the molecular basis of how organisms adapt to the living environments encountered. In this review, we summarize the researches on the molecular mechanism of the adaptive evolution of Chiroptera, especially the recent researches at the genome levels, suggesting a far more complex evolutionary pattern and functional diversity than previously thought. In the future, along with the increasing numbers of Chiroptera species genomes available, new evolutionary patterns and functional divergence will be revealed, which can promote the further understanding of this animal group and the molecular mechanism of adaptive evolution.

Winter distribution and use of high elevation caves as foraging sites by the endangered Hawaiian hoary bat, Lasiurus cinereus semotus

USGS Publications Warehouse

Bonaccorso, Frank; Montoya-Aiona, Kristina; Pinzari, Corinna A.; Todd, Christopher M.

2016-01-01

We examine altitudinal movements involving unusual use of caves by Hawaiian hoary bats, Lasiurus cinereus semotus, during winter and spring in the Mauna Loa Forest Reserve (MLFR), Hawai‘i Island. Acoustic detection of hoary bat vocalizations, were recorded with regularity outside 13 lava tube cave entrances situated between 2,200 to 3,600 m asl from November 2012 to April 2013. Vocalizations were most numerous in November and December with the number of call events and echolocation pulses decreasing through the following months. Bat activity was positively correlated with air temperature and negatively correlated with wind speed. Visual searches found no evidence of hibernacula nor do Hawaiian hoary bats appear to shelter by day in these caves. Nevertheless, bats fly deep into caves as evidenced by numerous carcasses found in cave interiors. The occurrence of feeding buzzes around cave entrances and visual observations of bats flying in acrobatic fashion in cave interiors point to the use of these spaces as foraging sites. Peridroma moth species (Noctuidae), the only abundant nocturnal, flying insect sheltering in large numbers in rock rubble and on cave walls in the MLFR, apparently serve as the principal prey attracting hoary bats during winter to lava tube caves in the upper MLFR. Caves above 3,000 m on Mauna Loa harbor temperatures suitable for Pseudogymnoascus destructansfungi, the causative agent of White-nose Syndrome that is highly lethal to some species of North American cave-dwelling bats. We discuss the potential for White-nose Syndrome to establish and affect Hawaiian hoary bats.

Using sounds for making decisions: greater tube-nosed bats prefer antagonistic calls over non-communicative sounds when feeding

PubMed Central

Jiang, Tinglei; Long, Zhenyu; Ran, Xin; Zhao, Xue; Xu, Fei; Qiu, Fuyuan; Kanwal, Jagmeet S.

2016-01-01

ABSTRACT Bats vocalize extensively within different social contexts. The type and extent of information conveyed via their vocalizations and their perceptual significance, however, remains controversial and difficult to assess. Greater tube-nosed bats, Murina leucogaster, emit calls consisting of long rectangular broadband noise burst (rBNBl) syllables during aggression between males. To experimentally test the behavioral impact of these sounds for feeding, we deployed an approach and place-preference paradigm. Two food trays were placed on opposite sides and within different acoustic microenvironments, created by sound playback, within a specially constructed tent. Specifically, we tested whether the presence of rBNBl sounds at a food source effectively deters the approach of male bats in comparison to echolocation sounds and white noise. In each case, contrary to our expectation, males preferred to feed at a location where rBNBl sounds were present. We propose that the species-specific rBNBl provides contextual information, not present within non-communicative sounds, to facilitate approach towards a food source. PMID:27815241

Big brown bats (Eptesicus fuscus) maintain hearing sensitivity after exposure to intense band-limited noise.

PubMed

Simmons, Andrea Megela; Hom, Kelsey N; Simmons, James A

2017-03-01

Thresholds to short-duration narrowband frequency-modulated (FM) sweeps were measured in six big brown bats (Eptesicus fuscus) in a two-alternative forced choice passive listening task before and after exposure to band-limited noise (lower and upper frequencies between 10 and 50 kHz, 1 h, 116-119 dB sound pressure level root mean square; sound exposure level 152 dB). At recovery time points of 2 and 5 min post-exposure, thresholds varied from -4 to +4 dB from pre-exposure threshold estimates. Thresholds after sham (control) exposures varied from -6 to +2 dB from pre-exposure estimates. The small differences in thresholds after noise and sham exposures support the hypothesis that big brown bats do not experience significant temporary threshold shifts under these experimental conditions. These results confirm earlier findings showing stability of thresholds to broadband FM sweeps at longer recovery times after exposure to broadband noise. Big brown bats may have evolved a lessened susceptibility to noise-induced hearing losses, related to the special demands of echolocation.

Examining patterns of bat activity in Bandelier National Monument, New Mexico, using walking point transects

USGS Publications Warehouse

Ellison, L.E.; Everette, A.L.; Bogan, M.A.

2005-01-01

We conducted a preliminary study using small field crews, a single Anabat II detector coupled with a laptop computer, and point transects to examine patterns of bat activity at a scale of interest to local resource managers. The study was conducted during summers of 1996–1998 in Bandelier National Monument in the Jemez Mountains of northern New Mexico, a landscape with distinct vegetation zones and high species richness of bats. We developed simple models that described general patterns of acoustic activity within 4 vegetation zones based primarily on nightly variation and a qualitative index of habitat complexity. Bat acoustic activity (number of bat passes&sol point) did not vary dramatically among a limited sample of transects within a vegetation zone during 1996. In 1997 and 1998, single transects within each vegetation zone were established, and bat activity did not vary annually within these zones. Acoustic activity differed among the 4 vegetation zones of interest, with the greatest activity occurring in riparian canyon bottomland, intermediate activity in coniferous forest and a 1977 burned zone, and lowest activity in piñon-juniper woodlands. We identified 68.5% of 2,529 bat passes recorded during point-transect surveys to species using an echolocation call reference library we established for the area and qualitative characteristics of bat calls. Bat species richness and composition differed among vegetation zones. Results of these efforts were consistent with general knowledge of where different bat species typically forage and with the natural history of bats of New Mexico, suggesting such a method might have value for drawing inferences about bat activity in different vegetation zones.

Heard but not seen: Comparing bat assemblages and study methods in a mosaic landscape in the Western Ghats of India.

PubMed

Wordley, Claire F R; Sankaran, Mahesh; Mudappa, Divya; Altringham, John D

2018-04-01

We used capture (mist-netting) and acoustic methods to compare the species richness, abundance, and composition of a bat assemblage in different habitats in the Western Ghats of India. In the tropics, catching bats has been more commonly used as a survey method than acoustic recordings. In our study, acoustic methods based on recording echolocation calls detected greater bat activity and more species than mist-netting. However, some species were detected more frequently or exclusively by capture. Ideally, the two methods should be used together to compensate for the biases in each. Using combined capture and acoustic data, we found that protected forests, forest fragments, and shade coffee plantations hosted similar and diverse species assemblages, although some species were recorded more frequently in protected forests. Tea plantations contained very few species from the overall bat assemblage. In riparian habitats, a strip of forested habitat on the river bank improved the habitat for bats compared to rivers with tea planted up to each bank. Our results show that shade coffee plantations are better bat habitat than tea plantations in biodiversity hotspots. However, if tea is to be the dominant land use, forest fragments and riparian corridors can improve the landscape considerably for bats. We encourage coffee growers to retain traditional plantations with mature native trees, rather than reverting to sun grown coffee or coffee shaded by a few species of timber trees.

Single-locus species delimitation: a test of the mixed Yule-coalescent model, with an empirical application to Philippine round-leaf bats.

PubMed

Esselstyn, Jacob A; Evans, Ben J; Sedlock, Jodi L; Anwarali Khan, Faisal Ali; Heaney, Lawrence R

2012-09-22

Prospects for a comprehensive inventory of global biodiversity would be greatly improved by automating methods of species delimitation. The general mixed Yule-coalescent (GMYC) was recently proposed as a potential means of increasing the rate of biodiversity exploration. We tested this method with simulated data and applied it to a group of poorly known bats (Hipposideros) from the Philippines. We then used echolocation call characteristics to evaluate the plausibility of species boundaries suggested by GMYC. In our simulations, GMYC performed relatively well (errors in estimated species diversity less than 25%) when the product of the haploid effective population size (N(e)) and speciation rate (SR; per lineage per million years) was less than or equal to 10(5), while interspecific variation in N(e) was twofold or less. However, at higher but also biologically relevant values of N(e) × SR and when N(e) varied tenfold among species, performance was very poor. GMYC analyses of mitochondrial DNA sequences from Philippine Hipposideros suggest actual diversity may be approximately twice the current estimate, and available echolocation call data are mostly consistent with GMYC delimitations. In conclusion, we consider the GMYC model useful under some conditions, but additional information on N(e), SR and/or corroboration from independent character data are needed to allow meaningful interpretation of results.

Robust design of multiple trailing edge flaps for helicopter vibration reduction: A multi-objective bat algorithm approach

NASA Astrophysics Data System (ADS)

Mallick, Rajnish; Ganguli, Ranjan; Seetharama Bhat, M.

2015-09-01

The objective of this study is to determine an optimal trailing edge flap configuration and flap location to achieve minimum hub vibration levels and flap actuation power simultaneously. An aeroelastic analysis of a soft in-plane four-bladed rotor is performed in conjunction with optimal control. A second-order polynomial response surface based on an orthogonal array (OA) with 3-level design describes both the objectives adequately. Two new orthogonal arrays called MGB2P-OA and MGB4P-OA are proposed to generate nonlinear response surfaces with all interaction terms for two and four parameters, respectively. A multi-objective bat algorithm (MOBA) approach is used to obtain the optimal design point for the mutually conflicting objectives. MOBA is a recently developed nature-inspired metaheuristic optimization algorithm that is based on the echolocation behaviour of bats. It is found that MOBA inspired Pareto optimal trailing edge flap design reduces vibration levels by 73% and flap actuation power by 27% in comparison with the baseline design.

Habitat occupancy and detection of the pacific sheath-tailed bat (emballonura semicaudata) on aguiguan, commonwealth of the northern Mariana Islands

USGS Publications Warehouse

Gorresen, P.M.; Bonaccorso, F.J.; Pinzari, C.A.

2009-01-01

Occupancy analysis was used to quantify Pacific sheath-tailed bat (Emballonura semicaudata) foraging activity and its relationship to forest structure and proximity to cave roosts on Aguiguan Island in the Commonwealth of the Northern Mariana Islands. Bat occurrence was most closely associated with canopy cover, vegetation stature and distance to known roosts. The metrics generated by this study can serve as a quantitative baseline for future assessments of the status of this endangered species following changes in habitat due to management activities (e.g., feral goat control) or other factors (e.g., typhoon impacts). Additionally, we provide quantitative descriptions of the echolocation calls of E. semicaudata. Search-phase calls were characterized by a relatively narrow bandwidth and short pulse duration typical of insectivores that forage within vegetative clutter. Two distinctly characteristic frequencies were recorded: 30.97 ?? 1.08 kHz and 63.15 ?? 2.20 kHz ?? Museum and Institute of Zoology PAS.

Groups of bats improve sonar efficiency through mutual suppression of pulse emissions.

PubMed

Jarvis, Jenna; Jackson, William; Smotherman, Michael

2013-01-01

How bats adapt their sonar behavior to accommodate the noisiness of a crowded day roost is a mystery. Some bats change their pulse acoustics to enhance the distinction between theirs and another bat's echoes, but additional mechanisms are needed to explain the bat sonar system's exceptional resilience to jamming by conspecifics. Variable pulse repetition rate strategies offer one potential solution to this dynamic problem, but precisely how changes in pulse rate could improve sonar performance in social settings is unclear. Here we show that bats decrease their emission rates as population density increases, following a pattern that reflects a cumulative mutual suppression of each other's pulse emissions. Playback of artificially-generated echolocation pulses similarly slowed emission rates, demonstrating that suppression was mediated by hearing the pulses of other bats. Slower emission rates did not support an antiphonal emission strategy but did reduce the relative proportion of emitted pulses that overlapped with another bat's emissions, reducing the relative rate of mutual interference. The prevalence of acoustic interferences occurring amongst bats was empirically determined to be a linear function of population density and mean emission rates. Consequently as group size increased, small reductions in emission rates spread across the group partially mitigated the increase in interference rate. Drawing on lessons learned from communications networking theory we show how modest decreases in pulse emission rates can significantly increase the net information throughput of the shared acoustic space, thereby improving sonar efficiency for all individuals in a group. We propose that an automated acoustic suppression of pulse emissions triggered by bats hearing each other's emissions dynamically optimizes sonar efficiency for the entire group.

Parallel and convergent evolution of the dim-light vision gene RH1 in bats (Order: Chiroptera).

PubMed

Shen, Yong-Yi; Liu, Jie; Irwin, David M; Zhang, Ya-Ping

2010-01-21

Rhodopsin, encoded by the gene Rhodopsin (RH1), is extremely sensitive to light, and is responsible for dim-light vision. Bats are nocturnal mammals that inhabit poor light environments. Megabats (Old-World fruit bats) generally have well-developed eyes, while microbats (insectivorous bats) have developed echolocation and in general their eyes were degraded, however, dramatic differences in the eyes, and their reliance on vision, exist in this group. In this study, we examined the rod opsin gene (RH1), and compared its evolution to that of two cone opsin genes (SWS1 and M/LWS). While phylogenetic reconstruction with the cone opsin genes SWS1 and M/LWS generated a species tree in accord with expectations, the RH1 gene tree united Pteropodidae (Old-World fruit bats) and Yangochiroptera, with very high bootstrap values, suggesting the possibility of convergent evolution. The hypothesis of convergent evolution was further supported when nonsynonymous sites or amino acid sequences were used to construct phylogenies. Reconstructed RH1 sequences at internal nodes of the bat species phylogeny showed that: (1) Old-World fruit bats share an amino acid change (S270G) with the tomb bat; (2) Miniopterus share two amino acid changes (V104I, M183L) with Rhinolophoidea; (3) the amino acid replacement I123V occurred independently on four branches, and the replacements L99M, L266V and I286V occurred each on two branches. The multiple parallel amino acid replacements that occurred in the evolution of bat RH1 suggest the possibility of multiple convergences of their ecological specialization (i.e., various photic environments) during adaptation for the nocturnal lifestyle, and suggest that further attention is needed on the study of the ecology and behavior of bats.

Groups of bats improve sonar efficiency through mutual suppression of pulse emissions

PubMed Central

Jarvis, Jenna; Jackson, William; Smotherman, Michael

2013-01-01

How bats adapt their sonar behavior to accommodate the noisiness of a crowded day roost is a mystery. Some bats change their pulse acoustics to enhance the distinction between theirs and another bat's echoes, but additional mechanisms are needed to explain the bat sonar system's exceptional resilience to jamming by conspecifics. Variable pulse repetition rate strategies offer one potential solution to this dynamic problem, but precisely how changes in pulse rate could improve sonar performance in social settings is unclear. Here we show that bats decrease their emission rates as population density increases, following a pattern that reflects a cumulative mutual suppression of each other's pulse emissions. Playback of artificially-generated echolocation pulses similarly slowed emission rates, demonstrating that suppression was mediated by hearing the pulses of other bats. Slower emission rates did not support an antiphonal emission strategy but did reduce the relative proportion of emitted pulses that overlapped with another bat's emissions, reducing the relative rate of mutual interference. The prevalence of acoustic interferences occurring amongst bats was empirically determined to be a linear function of population density and mean emission rates. Consequently as group size increased, small reductions in emission rates spread across the group partially mitigated the increase in interference rate. Drawing on lessons learned from communications networking theory we show how modest decreases in pulse emission rates can significantly increase the net information throughput of the shared acoustic space, thereby improving sonar efficiency for all individuals in a group. We propose that an automated acoustic suppression of pulse emissions triggered by bats hearing each other's emissions dynamically optimizes sonar efficiency for the entire group. PMID:23781208

Parallel and Convergent Evolution of the Dim-Light Vision Gene RH1 in Bats (Order: Chiroptera)

PubMed Central

Shen, Yong-Yi; Liu, Jie; Irwin, David M.; Zhang, Ya-Ping

2010-01-01

Rhodopsin, encoded by the gene Rhodopsin (RH1), is extremely sensitive to light, and is responsible for dim-light vision. Bats are nocturnal mammals that inhabit poor light environments. Megabats (Old-World fruit bats) generally have well-developed eyes, while microbats (insectivorous bats) have developed echolocation and in general their eyes were degraded, however, dramatic differences in the eyes, and their reliance on vision, exist in this group. In this study, we examined the rod opsin gene (RH1), and compared its evolution to that of two cone opsin genes (SWS1 and M/LWS). While phylogenetic reconstruction with the cone opsin genes SWS1 and M/LWS generated a species tree in accord with expectations, the RH1 gene tree united Pteropodidae (Old-World fruit bats) and Yangochiroptera, with very high bootstrap values, suggesting the possibility of convergent evolution. The hypothesis of convergent evolution was further supported when nonsynonymous sites or amino acid sequences were used to construct phylogenies. Reconstructed RH1 sequences at internal nodes of the bat species phylogeny showed that: (1) Old-World fruit bats share an amino acid change (S270G) with the tomb bat; (2) Miniopterus share two amino acid changes (V104I, M183L) with Rhinolophoidea; (3) the amino acid replacement I123V occurred independently on four branches, and the replacements L99M, L266V and I286V occurred each on two branches. The multiple parallel amino acid replacements that occurred in the evolution of bat RH1 suggest the possibility of multiple convergences of their ecological specialization (i.e., various photic environments) during adaptation for the nocturnal lifestyle, and suggest that further attention is needed on the study of the ecology and behavior of bats. PMID:20098620

Directional Receiver for Biomimetic Sonar System

NASA Astrophysics Data System (ADS)

Guarato, Francesco; Andrews, Heather; Windmill, James F.; Jackson, Joseph; Gachagan, Anthony

An ultrasonic localization method for a sonar system equipped with an emitter and two directional receivers and inspired by bat echolocation uses knowledge of the beam pattern of the receivers to estimate target orientation. Rousettus leschenaultii's left ear constitutes the model for the design of the optimal receiver for this sonar system and 3D printing was used to fabricate receiver structures comprising of two truncated cones with an elliptical external perimeter and a parabolic flare rate in the upper part. Measurements show one receiver has a predominant lobe in the same region and with similar attenuation values as the bat ear model. The final sonar system is to be mounted on vehicular and aerial robots which require remote control for motion and sensors for estimation of each robot's location.

Molecular cloning and evolutionary analysis of the GJA1 (connexin43) gene from bats (Chiroptera).

PubMed

Wang, Li; Li, Gang; Wang, Jinhong; Ye, Shaohui; Jones, Gareth; Zhang, Shuyi

2009-04-01

Gap junction protein connexin43 (Cx43), encoded by the GJA1 gene, is the most abundant connexin in the cardiovascular system and was reported as a crucial factor maintaining cardiac electrical conduction, as well as having a very important function in facilitating the recycling of potassium ions from hair cells in the cochlea back into the cochlear endolymph during auditory transduction processes. In mammals, bats are the only taxon possessing powered flight, placing exceptional demand on many organismal processes. To meet the demands of flying, the hearts of bats show many specialties. Moreover, ultrasonic echolocation allows bat species to orientate and often detect and locate food in darkness. In this study, we cloned the full-length coding region of GJA1 gene from 12 different species of bats and obtained orthologous sequences from other mammals. We used the maximum likelihood method to analyse the evolution of GJA1 gene in mammals and the lineage of bats. Our results showed this gene is much conserved in mammals, as well as in bats' lineage. Compared with other mammals, we found one private amino acid substitution shared by bats, which is located on the inner loop domain, as well as some species-specific amino acid substitutions. The evolution rate analyses showed the signature of purifying selection on not only different classification level lineages but also the different domains and amino acid residue sites of this gene. Also, we suggested that GJA1 gene could be used as a good molecular marker to do the phylogenetic reconstruction.

The simple ears of noctuoid moths are tuned to the calls of their sympatric bat community.

PubMed

ter Hofstede, Hannah M; Goerlitz, Holger R; Ratcliffe, John M; Holderied, Marc W; Surlykke, Annemarie

2013-11-01

Insects with bat-detecting ears are ideal animals for investigating sensory system adaptations to predator cues. Noctuid moths have two auditory receptors (A1 and A2) sensitive to the ultrasonic echolocation calls of insectivorous bats. Larger moths are detected at greater distances by bats than smaller moths. Larger moths also have lower A1 best thresholds, allowing them to detect bats at greater distances and possibly compensating for their increased conspicuousness. Interestingly, the sound frequency at the lowest threshold is lower in larger than in smaller moths, suggesting that the relationship between threshold and size might vary across frequencies used by different bat species. Here, we demonstrate that the relationships between threshold and size in moths were only significant at some frequencies, and these frequencies differed between three locations (UK, Canada and Denmark). The relationships were more likely to be significant at call frequencies used by proportionately more bat species in the moths' specific bat community, suggesting an association between the tuning of moth ears and the cues provided by sympatric predators. Additionally, we found that the best threshold and best frequency of the less sensitive A2 receptor are also related to size, and that these relationships hold when controlling for evolutionary relationships. The slopes of best threshold versus size differ, however, such that the difference in threshold between A1 and A2 is greater for larger than for smaller moths. The shorter time from A1 to A2 excitation in smaller than in larger moths could potentially compensate for shorter absolute detection distances in smaller moths.

Does nasal echolocation influence the modularity of the mammal skull?

PubMed

Santana, S E; Lofgren, S E

2013-11-01

In vertebrates, changes in cranial modularity can evolve rapidly in response to selection. However, mammals have apparently maintained their pattern of cranial integration throughout their evolutionary history and across tremendous morphological and ecological diversity. Here, we use phylogenetic, geometric morphometric and comparative analyses to test the hypothesis that the modularity of the mammalian skull has been remodelled in rhinolophid bats due to the novel and critical function of the nasal cavity in echolocation. We predicted that nasal echolocation has resulted in the evolution of a third cranial module, the 'nasal dome', in addition to the braincase and rostrum modules, which are conserved across mammals. We also test for similarities in the evolution of skull shape in relation to habitat across rhinolophids. We find that, despite broad variation in the shape of the nasal dome, the integration of the rhinolophid skull is highly consistent with conserved patterns of modularity found in other mammals. Across their broad geographical distribution, cranial shape in rhinolophids follows two major divisions that could reflect adaptations to dietary and environmental differences in African versus South Asian distributions. Our results highlight the potential of a relatively simple modular template to generate broad morphological and functional variation in mammals. © 2013 The Authors. Journal of Evolutionary Biology © 2013 European Society For Evolutionary Biology.

Ignoring the irrelevant: auditory tolerance of audible but innocuous sounds in the bat-detecting ears of moths

NASA Astrophysics Data System (ADS)

Fullard, James H.; Ratcliffe, John M.; Jacobs, David S.

2008-03-01

Noctuid moths listen for the echolocation calls of hunting bats and respond to these predator cues with evasive flight. The African bollworm moth, Helicoverpa armigera, feeds at flowers near intensely singing cicadas, Platypleura capensis, yet does not avoid them. We determined that the moth can hear the cicada by observing that both of its auditory receptors (A1 and A2 cells) respond to the cicada’s song. The firing response of the A1 cell rapidly adapts to the song and develops spike periods in less than a second that are in excess of those reported to elicit avoidance flight to bats in earlier studies. The possibility also exists that for at least part of the day, sensory input in the form of olfaction or vision overrides the moth’s auditory responses. While auditory tolerance appears to allow H. armigera to exploit a food resource in close proximity to acoustic interference, it may render their hearing defence ineffective and make them vulnerable to predation by bats during the evening when cicadas continue to sing. Our study describes the first field observation of an eared insect ignoring audible but innocuous sounds.

Insectivorous bats respond to vegetation complexity in urban green spaces.

PubMed

Suarez-Rubio, Marcela; Ille, Christina; Bruckner, Alexander

2018-03-01

Structural complexity is known to determine habitat quality for insectivorous bats, but how bats respond to habitat complexity in highly modified areas such as urban green spaces has been little explored. Furthermore, it is uncertain whether a recently developed measure of structural complexity is as effective as field-based surveys when applied to urban environments. We assessed whether image-derived structural complexity (MIG) was as/more effective than field-based descriptors in this environment and evaluated the response of insectivorous bats to structural complexity in urban green spaces. Bat activity and species richness were assessed with ultrasonic devices at 180 locations within green spaces in Vienna, Austria. Vegetation complexity was assessed using 17 field-based descriptors and by calculating the mean information gain (MIG) using digital images. Total bat activity and species richness decreased with increasing structural complexity of canopy cover, suggesting maneuverability and echolocation (sensorial) challenges for bat species using the canopy for flight and foraging. The negative response of functional groups to increased complexity was stronger for open-space foragers than for edge-space foragers. Nyctalus noctula , a species foraging in open space, showed a negative response to structural complexity, whereas Pipistrellus pygmaeus , an edge-space forager, was positively influenced by the number of trees. Our results show that MIG is a useful, time- and cost-effective tool to measure habitat complexity that complemented field-based descriptors. Response of insectivorous bats to structural complexity was group- and species-specific, which highlights the need for manifold management strategies (e.g., increasing or reinstating the extent of ground vegetation cover) to fulfill different species' requirements and to conserve insectivorous bats in urban green spaces.

Bats Can Use Magnetic Compass in Foraging Behavior

NASA Astrophysics Data System (ADS)

Tian, L.; Zhang, B.; Pan, Y.; Zhu, R.

2016-12-01

Foraging plays an important role in an animal's ability to survive and reproduce. It is widely recognized that many animals and microorganisms can use geomagnetic compass in migration or homing orientation. Among them, bats, the only flying mammals, can use the magnetic compass in migrating orientations. For instance, we found the migratory microbat, Nyctalus plancyi, could use the magnetic polarity compass in roosting orientation under the strength range at least from a much weaker magnetic field than the present-day geomagnetic field (as low as 10 μT) to up to stronger magnetic field (100 μT). This high sensitivity to magnetic fields intensity may explain how magnetic orientation could have long-term evolved in bats even as the Earth's magnetic field strength varied as the polarity reversed many times in the past. Recently, we carried out foraging behavioral experiments on N. plancyi under various magnetic field conditions. Interestingly, it has shown that, although the auditory including echolocation, or olfactory sense may be the primary methods for seeking food under totally dark circumstance, the bats showed preferred foraging orientations at the magnetic north-south directions when any other sensory cues are insufficient for location of the food. It confirmed that bats could optimally use multiple directional cues including the geomagnetic field in their foraging in field. When bats foraging, they would navigate along the magnetic field direction if there were no direct sensory cues. As it gets close, the direct cues from food would guide them to the food.

The evolution of sensory divergence in the context of limited gene flow in the bumblebee bat

PubMed Central

Puechmaille, Sébastien J.; Gouilh, Meriadeg Ar; Piyapan, Piyathip; Yokubol, Medhi; Mie, Khin Mie; Bates, Paul J.; Satasook, Chutamas; Nwe, Tin; Bu, Si Si Hla; Mackie, Iain J.; Petit, Eric J.; Teeling, Emma C.

2011-01-01

The sensory drive theory of speciation predicts that populations of the same species inhabiting different environments can differ in sensory traits, and that this sensory difference can ultimately drive speciation. However, even in the best-known examples of sensory ecology driven speciation, it is uncertain whether the variation in sensory traits is the cause or the consequence of a reduction in levels of gene flow. Here we show strong genetic differentiation, no gene flow and large echolocation differences between the allopatric Myanmar and Thai populations of the world's smallest mammal, Craseonycteris thonglongyai, and suggest that geographic isolation most likely preceded sensory divergence. Within the geographically continuous Thai population, we show that geographic distance has a primary role in limiting gene flow rather than echolocation divergence. In line with sensory-driven speciation models, we suggest that in C. thonglongyai, limited gene flow creates the suitable conditions that favour the evolution of sensory divergence via local adaptation. PMID:22146392

The Complexity of Background Clutter Affects Nectar Bat Use of Flower Odor and Shape Cues.

PubMed

Muchhala, Nathan; Serrano, Diana

2015-01-01

Given their small size and high metabolism, nectar bats need to be able to quickly locate flowers during foraging bouts. Chiropterophilous plants depend on these bats for their reproduction, thus they also benefit if their flowers can be easily located, and we would expect that floral traits such as odor and shape have evolved to maximize detection by bats. However, relatively little is known about the importance of different floral cues during foraging bouts. In the present study, we undertook a set of flight cage experiments with two species of nectar bats (Anoura caudifer and A. geoffroyi) and artificial flowers to compare the importance of shape and scent cues in locating flowers. In a training phase, a bat was presented an artificial flower with a given shape and scent, whose position was constantly shifted to prevent reliance on spatial memory. In the experimental phase, two flowers were presented, one with the training-flower scent and one with the training-flower shape. For each experimental repetition, we recorded which flower was located first, and then shifted flower positions. Additionally, experiments were repeated in a simple environment, without background clutter, or a complex environment, with a background of leaves and branches. Results demonstrate that bats visit either flower indiscriminately with simple backgrounds, with no significant difference in terms of whether they visit the training-flower odor or training-flower shape first. However, in a complex background olfaction was the most important cue; scented flowers were consistently located first. This suggests that for well-exposed flowers, without obstruction from clutter, vision and/or echolocation are sufficient in locating them. In more complex backgrounds, nectar bats depend more heavily on olfaction during foraging bouts.

The Complexity of Background Clutter Affects Nectar Bat Use of Flower Odor and Shape Cues

PubMed Central

Muchhala, Nathan; Serrano, Diana

2015-01-01

Given their small size and high metabolism, nectar bats need to be able to quickly locate flowers during foraging bouts. Chiropterophilous plants depend on these bats for their reproduction, thus they also benefit if their flowers can be easily located, and we would expect that floral traits such as odor and shape have evolved to maximize detection by bats. However, relatively little is known about the importance of different floral cues during foraging bouts. In the present study, we undertook a set of flight cage experiments with two species of nectar bats (Anoura caudifer and A. geoffroyi) and artificial flowers to compare the importance of shape and scent cues in locating flowers. In a training phase, a bat was presented an artificial flower with a given shape and scent, whose position was constantly shifted to prevent reliance on spatial memory. In the experimental phase, two flowers were presented, one with the training-flower scent and one with the training-flower shape. For each experimental repetition, we recorded which flower was located first, and then shifted flower positions. Additionally, experiments were repeated in a simple environment, without background clutter, or a complex environment, with a background of leaves and branches. Results demonstrate that bats visit either flower indiscriminately with simple backgrounds, with no significant difference in terms of whether they visit the training-flower odor or training-flower shape first. However, in a complex background olfaction was the most important cue; scented flowers were consistently located first. This suggests that for well-exposed flowers, without obstruction from clutter, vision and/or echolocation are sufficient in locating them. In more complex backgrounds, nectar bats depend more heavily on olfaction during foraging bouts. PMID:26445216

Size Constancy in Bat Biosonar? Perceptual Interaction of Object Aperture and Distance

PubMed Central

Heinrich, Melina; Wiegrebe, Lutz

2013-01-01

Perception and encoding of object size is an important feature of sensory systems. In the visual system object size is encoded by the visual angle (visual aperture) on the retina, but the aperture depends on the distance of the object. As object distance is not unambiguously encoded in the visual system, higher computational mechanisms are needed. This phenomenon is termed “size constancy”. It is assumed to reflect an automatic re-scaling of visual aperture with perceived object distance. Recently, it was found that in echolocating bats, the ‘sonar aperture’, i.e., the range of angles from which sound is reflected from an object back to the bat, is unambiguously perceived and neurally encoded. Moreover, it is well known that object distance is accurately perceived and explicitly encoded in bat sonar. Here, we addressed size constancy in bat biosonar, recruiting virtual-object techniques. Bats of the species Phyllostomus discolor learned to discriminate two simple virtual objects that only differed in sonar aperture. Upon successful discrimination, test trials were randomly interspersed using virtual objects that differed in both aperture and distance. It was tested whether the bats spontaneously assigned absolute width information to these objects by combining distance and aperture. The results showed that while the isolated perceptual cues encoding object width, aperture, and distance were all perceptually well resolved by the bats, the animals did not assign absolute width information to the test objects. This lack of sonar size constancy may result from the bats relying on different modalities to extract size information at different distances. Alternatively, it is conceivable that familiarity with a behaviorally relevant, conspicuous object is required for sonar size constancy, as it has been argued for visual size constancy. Based on the current data, it appears that size constancy is not necessarily an essential feature of sonar perception in bats. PMID:23630598

Size constancy in bat biosonar? Perceptual interaction of object aperture and distance.

PubMed

Heinrich, Melina; Wiegrebe, Lutz

2013-01-01

Perception and encoding of object size is an important feature of sensory systems. In the visual system object size is encoded by the visual angle (visual aperture) on the retina, but the aperture depends on the distance of the object. As object distance is not unambiguously encoded in the visual system, higher computational mechanisms are needed. This phenomenon is termed "size constancy". It is assumed to reflect an automatic re-scaling of visual aperture with perceived object distance. Recently, it was found that in echolocating bats, the 'sonar aperture', i.e., the range of angles from which sound is reflected from an object back to the bat, is unambiguously perceived and neurally encoded. Moreover, it is well known that object distance is accurately perceived and explicitly encoded in bat sonar. Here, we addressed size constancy in bat biosonar, recruiting virtual-object techniques. Bats of the species Phyllostomus discolor learned to discriminate two simple virtual objects that only differed in sonar aperture. Upon successful discrimination, test trials were randomly interspersed using virtual objects that differed in both aperture and distance. It was tested whether the bats spontaneously assigned absolute width information to these objects by combining distance and aperture. The results showed that while the isolated perceptual cues encoding object width, aperture, and distance were all perceptually well resolved by the bats, the animals did not assign absolute width information to the test objects. This lack of sonar size constancy may result from the bats relying on different modalities to extract size information at different distances. Alternatively, it is conceivable that familiarity with a behaviorally relevant, conspicuous object is required for sonar size constancy, as it has been argued for visual size constancy. Based on the current data, it appears that size constancy is not necessarily an essential feature of sonar perception in bats.

Fishing Technique of Long-Fingered Bats Was Developed from a Primary Reaction to Disappearing Target Stimuli.

PubMed

Aizpurua, Ostaizka; Alberdi, Antton; Aihartza, Joxerra; Garin, Inazio

2016-01-01

Behavioral plasticity is a key feature allowing animals to broaden their dietary niche when novel food resources become available, and long-fingered bats provide an appropriate model system to study the underpinnings of behavioral plasticity, since although generally being an insectivorous species, some individuals have been reported to catch fish. Aiming to get insight into the origin of fishing behavior in long-fingered bats, we studied in the field the differences in sensorial and mechanical reactions to insect-like (stationary) and fish-like (temporary) prey stimuli between well-known piscivorous and strictly insectivorous individuals. Both piscivorous and insectivorous individuals exhibited a qualitatively similar reaction to temporary target stimuli (longer and deeper dips and terminal echolocation phase skewed towards buzz I compared to stationary stimuli). Nevertheless, the quantitative differences observed in the sensorial and mechanical features (the intensity of the shift was significantly greater in piscivorous than in insectivorous individuals) show that piscivorous individuals have honed their capture technique likely enhancing the fishing success. Thus, our results suggest that the fishing technique was developed from a primary reaction shared by all long-fingered bats. All individuals seem to be mechanically and sensorially adapted to detect and capture fish, although under appropriate environmental conditions, they would further improve their technique by experience and/or social learning.

Spontaneous, generalized lipidosis in captive greater horseshoe bats (Rhinolophus ferrumequinum).

PubMed

Gozalo, Alfonso S; Schwiebert, Rebecca S; Metzner, Walter; Lawson, Gregory W

2005-11-01

During a routine 6-month quarantine period, 3 of 34 greater horseshoe bats (Rhinolophus ferrumequinum) captured in mainland China and transported to the United States for use in echolocation studies were found dead with no prior history of illness. All animals were in good body condition at the time of death. At necropsy, a large amount of white fat was found within the subcutis, especially in the sacrolumbar region. The liver, kidneys, and heart were diffusely tan in color. Microscopic examination revealed that hepatocytes throughout the liver were filled with lipid, and in some areas, lipid granulomas were present. renal lesions included moderate amounts of lipid in the cortical tubular epithelium and large amounts of protein and lipid within Bowman's capsules in the glomeruli. In addition, one bat had large lipid vacuoles diffusely distributed throughout the myocardium. The exact pathologic mechanism inducing the hepatic, renal, and cardiac lipidosis is unknown. The horseshoe bats were captured during hibernation and immediately transported to the United States. It is possible that the large amount of fat stored coupled with changes in photoperiod, lack of exercise, and/or the stress of captivity might have contributed to altering the normal metabolic processes, leading to anorexia and consequently lipidosis in these animals.

Ultrasound avoidance behaviour in the bushcricket Tettigonia viridissima (Orthoptera: Tettigoniidae).

PubMed

Schulze, W; Schul, J

2001-02-01

The responses of female Tettigonia viridissima to simulated bat echolocation calls were examined during tethered flight. The insects responded with three distinct behaviours, which occurred at graded stimulus intensities. At low intensities (threshold 54 dB SPL), T. viridissima responded by steering away from the sound source (negative phonotaxis). At intensities approximately 10 dB higher, beating of the hindwing was interrupted, although the insect remained in the flight posture. A diving response (cessation of the wingbeat, closure of the forewings and alignment of the legs against the body) occurred with a threshold of 76 dB SPL. Considering these thresholds, we estimate that the diving response occurs at approximately the sound amplitude at which many aerial-hawking bats first receive echoes from the insect. The other behaviours probably occur before the bat detects the insect and should therefore be interpreted as early avoidance behaviours. The repertoire of startle responses in T. viridissima, with directional and non-directional components, is similar to those of crickets and moths, but quite different from those described for another bushcricket (Neoconocephalus ensiger), which shows only a non-directional response. This supports the conclusion that bat-evasive behaviours are not conserved within the Tettigoniidae, but instead are shaped by the ecological constraints of the insects.

Simple syllabic calls accompany discrete behavior patterns in captive Pteronotus parnellii: an illustration of the motivation-structure hypothesis.

PubMed

Clement, Matthew J; Kanwal, Jagmeet S

2012-01-01

Mustached bats, Pteronotus parnellii, are highly social and vocal. Individuals of this species roost in tight clusters, and emit an acoustically rich repertoire of calls whose behavioral significance is largely unknown. We recorded their social and vocal behaviors within a colony housed under semi-natural conditions. We also quantified the spatial spread of each bat's roosting location and discovered that this was relatively fixed and roughly confined to an individual's body width. The spatial precision in roosting was accompanied by an equally remarkable match between specific vocalizations and well-timed, discrete, identifiable postures/behaviors, as revealed by logistic regression analysis. The bodily behaviors included crouching, marking, yawning, nipping, flicking, fighting, kissing, inspecting, and fly-bys. Two echolocation-like calls were used to maintain spacing in the colony, two noisy broadband calls were emitted during fights, two tonal calls conveyed fear, and another tonal call signaled appeasement. Overall, the results establish that mustached bats exhibit complex social interactions common to other social mammals. The correspondence of relatively low frequency and noisy, broadband calls with aggression, and of tonal, high frequency calls with fear supports Morton's Motivation-Structure hypothesis, and establishes a link between motivation and the acoustic structure of social calls emitted by mustached bats.

Simple Syllabic Calls Accompany Discrete Behavior Patterns in Captive Pteronotus parnellii: An Illustration of the Motivation-Structure Hypothesis

PubMed Central

Clement, Matthew J.; Kanwal, Jagmeet S.

2012-01-01

Mustached bats, Pteronotus parnellii, are highly social and vocal. Individuals of this species roost in tight clusters, and emit an acoustically rich repertoire of calls whose behavioral significance is largely unknown. We recorded their social and vocal behaviors within a colony housed under semi-natural conditions. We also quantified the spatial spread of each bat's roosting location and discovered that this was relatively fixed and roughly confined to an individual's body width. The spatial precision in roosting was accompanied by an equally remarkable match between specific vocalizations and well-timed, discrete, identifiable postures/behaviors, as revealed by logistic regression analysis. The bodily behaviors included crouching, marking, yawning, nipping, flicking, fighting, kissing, inspecting, and fly-bys. Two echolocation-like calls were used to maintain spacing in the colony, two noisy broadband calls were emitted during fights, two tonal calls conveyed fear, and another tonal call signaled appeasement. Overall, the results establish that mustached bats exhibit complex social interactions common to other social mammals. The correspondence of relatively low frequency and noisy, broadband calls with aggression, and of tonal, high frequency calls with fear supports Morton's Motivation-Structure hypothesis, and establishes a link between motivation and the acoustic structure of social calls emitted by mustached bats. PMID:22693429

Listening in Pheromone Plumes: Disruption of Olfactory-Guided Mate Attraction in a Moth by a Bat-Like Ultrasound

PubMed Central

Svenssona, Glenn P.; Löfstedt, Christer; Skals, Niels

2007-01-01

Nocturnal moths often use sex pheromones to find mates and ultrasonic hearing to evade echolocating bat predators. Male moths, when confronted with both pheromones and sound, thus have to trade off reproduction and predator avoidance depending on the relative strengths of the perceived conflicting stimuli. The ultrasonic hearing of Plodia interpunctella was investigated. A threshold curve for evasive reaction to ultrasound of tethered moths was established, and the frequency of best hearing was found to be between 40 and 70 kHz. Flight tunnel experiments were performed where males orienting in a sex pheromone plume were stimulated with 50 kHz pulses of different intensities. Pheromone-stimulated males showed increased defensive response with increased intensity of the sound stimulus, and the acoustic cue had long-lasting effects on their pheromone-mediated flight, revealing a cost associated with vital evasive behaviours. PMID:20331396

Bat Response to Differing Fire Severity in Mixed-Conifer Forest California, USA

PubMed Central

Heady, Paul A.; Hayes, John P.; Frick, Winifred F.

2013-01-01

Wildlife response to natural disturbances such as fire is of conservation concern to managers, policy makers, and scientists, yet information is scant beyond a few well-studied groups (e.g., birds, small mammals). We examined the effects of wildfire severity on bats, a taxon of high conservation concern, at both the stand (<1 ha) and landscape scale in response to the 2002 McNally fire in the Sierra Nevada region of California, USA. One year after fire, we conducted surveys of echolocation activity at 14 survey locations, stratified in riparian and upland habitat, in mixed-conifer forest habitats spanning three levels of burn severity: unburned, moderate, and high. Bat activity in burned areas was either equivalent or higher than in unburned stands for all six phonic groups measured, with four groups having significantly greater activity in at least one burn severity level. Evidence of differentiation between fire severities was observed with some Myotis species having higher levels of activity in stands of high-severity burn. Larger-bodied bats, typically adapted to more open habitat, showed no response to fire. We found differential use of riparian and upland habitats among the phonic groups, yet no interaction of habitat type by fire severity was found. Extent of high-severity fire damage in the landscape had no effect on activity of bats in unburned sites suggesting no landscape effect of fire on foraging site selection and emphasizing stand-scale conditions driving bat activity. Results from this fire in mixed-conifer forests of California suggest that bats are resilient to landscape-scale fire and that some species are preferentially selecting burned areas for foraging, perhaps facilitated by reduced clutter and increased post-fire availability of prey and roosts. PMID:23483936

Narrow sound pressure level tuning in the auditory cortex of the bats Molossus molossus and Macrotus waterhousii.

PubMed

Macías, Silvio; Hechavarría, Julio C; Cobo, Ariadna; Mora, Emanuel C

2014-03-01

In the auditory system, tuning to sound level appears in the form of non-monotonic response-level functions that depict the response of a neuron to changing sound levels. Neurons with non-monotonic response-level functions respond best to a particular sound pressure level (defined as "best level" or level evoking the maximum response). We performed a comparative study on the location and basic functional organization of the auditory cortex in the gleaning bat, Macrotus waterhousii, and the aerial-hawking bat, Molossus molossus. Here, we describe the response-level function of cortical units in these two species. In the auditory cortices of M. waterhousii and M. molossus, the characteristic frequency of the units increased from caudal to rostral. In M. waterhousii, there was an even distribution of characteristic frequencies while in M. molossus there was an overrepresentation of frequencies present within echolocation pulses. In both species, most of the units showed best levels in a narrow range, without an evident topography in the amplitopic organization, as described in other species. During flight, bats decrease the intensity of their emitted pulses when they approach a prey item or an obstacle resulting in maintenance of perceived echo intensity. Narrow level tuning likely contributes to the extraction of echo amplitudes facilitating echo-intensity compensation. For aerial-hawking bats, like M. molossus, receiving echoes within the optimal sensitivity range can help the bats to sustain consistent analysis of successive echoes without distortions of perception caused by changes in amplitude. Copyright © 2013 Elsevier B.V. All rights reserved.

The foraging ecology of the mountain long-eared bat Plecotus macrobullaris revealed with DNA mini-barcodes.

PubMed

Alberdi, Antton; Garin, Inazio; Aizpurua, Ostaizka; Aihartza, Joxerra

2012-01-01

Molecular analysis of diet overcomes the considerable limitations of traditional techniques for identifying prey remains in bat faeces. We collected faeces from individual Mountain Long-eared Bats Plecotus macrobullaris trapped using mist nets during the summers of 2009 and 2010 in the Pyrenees. We analysed their diet using DNA mini-barcodes to identify prey species. In addition, we inferred some basic features of the bat's foraging ecology that had not yet been addressed. P. macrobullaris fed almost exclusively on moths (97.8%). As prey we detected one dipteran genus (Tipulidae) and 29 moth taxa: 28 were identified at species level (23 Noctuidae, 1 Crambidae, 1 Geometridae, 1 Pyralidae, 1 Sphingidae, 1 Tortricidae), and one at genus level (Rhyacia sp., Noctuidae). Known ecological information about the prey species allowed us to determine that bats had foraged at elevations between 1,500 and 2,500 m amsl (above mean sea level), mostly in subalpine meadows, followed by other open habitats such as orophilous grasslands and alpine meadows. No forest prey species were identified in the diet. As 96.4% of identified prey species were tympanate moths and no evidence of gleaning behaviour was revealed, we suggest P. macrobullaris probably forages by aerial hawking using faint echolocation pulses to avoid detection by hearing moths. As we could identify 87.8% of the analysed sequences (64.1% of the MOTUs, Molecular Operational Taxonomic Units) at species level, we conclude that DNA mini-barcodes are a very useful tool to analyse the diet of moth-specialist bats.

Noise interference with echo delay discrimination in bat biosonar.

PubMed

Simmons, J A

2017-11-01

Echolocating big brown bats (Eptesicus fuscus) were trained in a two-choice task to discriminate differences in the delay of electronic echoes at 1.7 ms delay (30 cm simulated range). Difference thresholds (∼45 μs) were comparable to previously published results. At selected above-threshold differences (116 and 232 μs delay), performance was measured in the presence of wideband random noise at increasing amplitudes in 10-dB steps to determine the noise level that prevented discrimination. Performance eventually failed, but the bats increased the amplitude and duration of their broadcasts to compensate for increasing noise, which allowed performance to persist at noise levels about 25 dB higher than without compensation. In the 232-μs delay discrimination condition, echo signal-to-noise ratio (2E/N 0 ) was 8-10 dB at the noise level that depressed performance to chance. Predicted echo-delay accuracy using big brown bat signals follows the Cramér-Rao bound for signal-to-noise ratios above 15 dB, but worsens below 15 dB due to side-peak ambiguity. At 2E/N 0  = 7-10 dB, predicted Cramér-Rao delay accuracy would be about 1 μs; considering side-peak ambiguity it would be about 200-300 μs. The bats' 232 μs performance reflects the intrusion of side-peak ambiguity into delay accuracy at low signal-to-noise ratios.

Stereotypical rapid source level regulation in the harbour porpoise biosonar

NASA Astrophysics Data System (ADS)

Linnenschmidt, Meike; Kloepper, Laura N.; Wahlberg, Magnus; Nachtigall, Paul E.

2012-09-01

Some odontocetes and bats vary both click intensity and receiver sensitivity during echolocation, depending on target range. It is not known how this so-called automatic gain control is regulated by the animal. The source level of consecutive echolocation clicks from a harbour porpoise was measured with a hydrophone array while the animal detected an aluminium cylinder at 2, 4 or 8 m distance in a go/no-go paradigm. On-axis clicks had source levels of 145-174 dB re 1 μPa peak-to-peak. During target-present trials the click trains reached comparable source levels independent of the range to the target after three clicks. After an additional click, the source level was reduced for the 2 and 4 m trials until it equalled the one-way transmission loss. During target-absent trials, the source level remained high throughout the entire click train. Given typical values of harbour porpoise inter-click intervals, the source level reduction commenced within a few 100 ms from the first click in the click train. This may indicate a sub-cortically regulated source level regulation in the harbour porpoise.

Blood miRNomes and transcriptomes reveal novel longevity mechanisms in the long-lived bat, Myotis myotis.

PubMed

Huang, Zixia; Jebb, David; Teeling, Emma C

2016-11-10

Chiroptera, the bats, are the only order of mammals capable of true self-powered flight. Bats exhibit a number of other exceptional traits such as echolocation, viral tolerance and, perhaps most puzzlingly, extreme longevity given their body size. Little is known about the molecular mechanisms driving their extended longevity particularly at the levels of gene expression and post-transcriptional regulation. To elucidate the molecular mechanisms that may underlie their unusual longevity, we have deep sequenced 246.5 million small RNA reads from whole blood of the long-lived greater mouse-eared bats, Myotis myotis, and conducted a series of genome-wide comparative analyses between bat and non-bat mammals (human, pig and cow) in both blood miRNomes and transcriptomes, for the first time. We identified 539 miRNA gene candidates from bats, of which 468 unique mature miRNA were obtained. More than half of these miRNA (65.1 %) were regarded as bat-specific, regulating genes involved in the immune, ageing and tumorigenesis pathways. We have also developed a stringent pipeline for genome-wide miRNome comparisons across species, and identified 37 orthologous miRNA groups shared with bat, human, pig and cow, 6 of which were differentially expressed. For bats, 3 out of 4 up-regulated miRNA (miR-101-3p, miR-16-5p, miR-143-3p) likely function as tumor suppressors against various kinds of cancers, while one down-regulated miRNA (miR-221-5p) acts as a tumorigenesis promoter in human breast and pancreatic cancers. Additionally, a genome-wide comparison of mRNA transcriptomes across species also revealed specific gene expression patterns in bats. 127 up-regulated genes were enriched mainly in mitotic cell cycle and DNA repair mechanisms, while 364 down-regulated genes were involved primarily in mitochondrial activity. Our comprehensive and integrative analyses revealed bat-specific and differentially expressed miRNA and mRNA that function in key longevity pathways, producing a distinct bat gene expression pattern. For the first time, we show that bats may possess unique regulatory mechanisms for resisting tumorigenesis, repairing cellular damage and preventing oxidative stresses, all of which likely contribute to the extraordinary lifespan of Myotis myotis.

Determining biosonar images using sparse representations.

PubMed

Fontaine, Bertrand; Peremans, Herbert

2009-05-01

Echolocating bats are thought to be able to create an image of their environment by emitting pulses and analyzing the reflected echoes. In this paper, the theory of sparse representations and its more recent further development into compressed sensing are applied to this biosonar image formation task. Considering the target image representation as sparse allows formulation of this inverse problem as a convex optimization problem for which well defined and efficient solution methods have been established. The resulting technique, referred to as L1-minimization, is applied to simulated data to analyze its performance relative to delay accuracy and delay resolution experiments. This method performs comparably to the coherent receiver for the delay accuracy experiments, is quite robust to noise, and can reconstruct complex target impulse responses as generated by many closely spaced reflectors with different reflection strengths. This same technique, in addition to reconstructing biosonar target images, can be used to simultaneously localize these complex targets by interpreting location cues induced by the bat's head related transfer function. Finally, a tentative explanation is proposed for specific bat behavioral experiments in terms of the properties of target images as reconstructed by the L1-minimization method.

Hypersalinity reduces the risk of cyanide toxicosis to insectivorous bats interacting with wastewater impoundments at gold mines.

PubMed

Griffiths, Stephen R; Donato, David B; Lumsden, Linda F; Coulson, Graeme

2014-01-01

Wildlife and livestock that ingest bioavailable cyanide compounds in gold mining tailings dams are known to experience cyanide toxicosis. Elevated levels of salinity in open impoundments have been shown to prevent wildlife cyanide toxicosis by reducing drinking and foraging. This finding appears to be consistent for diurnal wildlife interacting with open impoundments, however the risks to nocturnal wildlife of cyanide exposure are unknown. We investigated the activity of insectivorous bats in the airspace above both fresh (potable to wildlife) and saline water bodies at two gold mines in the goldfields of Western Australian. During this study, cyanide-bearing solutions stored in open impoundments at both mine sites were hypersaline (range=57,000-295,000 mg/L total dissolved solids (TDS)), well above known physiological tolerance of any terrestrial vertebrate. Bats used the airspace above each water body monitored, but were more active at fresh than saline water bodies. In addition, considerably more terminal echolocation buzz calls were recorded in the airspace above fresh than saline water bodies at both mine sites. However, it was not possible to determine whether these buzz calls corresponded to foraging or drinking bouts. No drinking bouts were observed in 33 h of thermal video footage recorded at one hypersaline tailings dam, suggesting that this water is not used for drinking. There is no information on salinity tolerances of bats, but it could be assumed that bats would not tolerate salinity in drinking water at concentrations greater than those documented as toxic for saline-adapted terrestrial wildlife. Therefore, when managing wastewater impoundments at gold mines to avoid wildlife mortalities, adopting a precautionary principle, bats are unlikely to drink solutions at salinity levels ≥50,000 mg/L TDS. © 2013 Published by Elsevier Inc.

RELAX: detecting relaxed selection in a phylogenetic framework.

PubMed

Wertheim, Joel O; Murrell, Ben; Smith, Martin D; Kosakovsky Pond, Sergei L; Scheffler, Konrad

2015-03-01

Relaxation of selective strength, manifested as a reduction in the efficiency or intensity of natural selection, can drive evolutionary innovation and presage lineage extinction or loss of function. Mechanisms through which selection can be relaxed range from the removal of an existing selective constraint to a reduction in effective population size. Standard methods for estimating the strength and extent of purifying or positive selection from molecular sequence data are not suitable for detecting relaxed selection, because they lack power and can mistake an increase in the intensity of positive selection for relaxation of both purifying and positive selection. Here, we present a general hypothesis testing framework (RELAX) for detecting relaxed selection in a codon-based phylogenetic framework. Given two subsets of branches in a phylogeny, RELAX can determine whether selective strength was relaxed or intensified in one of these subsets relative to the other. We establish the validity of our test via simulations and show that it can distinguish between increased positive selection and a relaxation of selective strength. We also demonstrate the power of RELAX in a variety of biological scenarios where relaxation of selection has been hypothesized or demonstrated previously. We find that obligate and facultative γ-proteobacteria endosymbionts of insects are under relaxed selection compared with their free-living relatives and obligate endosymbionts are under relaxed selection compared with facultative endosymbionts. Selective strength is also relaxed in asexual Daphnia pulex lineages, compared with sexual lineages. Endogenous, nonfunctional, bornavirus-like elements are found to be under relaxed selection compared with exogenous Borna viruses. Finally, selection on the short-wavelength sensitive, SWS1, opsin genes in echolocating and nonecholocating bats is relaxed only in lineages in which this gene underwent pseudogenization; however, selection on the functional medium/long-wavelength sensitive opsin, M/LWS1, is found to be relaxed in all echolocating bats compared with nonecholocating bats. © The Author 2014. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Reduction of emission level in approach signals of greater mouse-eared bats (Myotis myotis): No evidence for a closed loop control system for intensity compensation.

PubMed

Budenz, Tobias; Denzinger, Annette; Schnitzler, Hans-Ulrich

2018-01-01

Bats lower the emission SPL when approaching a target. The SPL reduction has been explained by intensity compensation which implies that bats adjust the emission SPL to perceive the retuning echoes at the same level. For a better understanding of this control mechanism we recorded the echolocation signals of four Myotis myotis with an onboard microphone when foraging in the passive mode for rustling mealworms offered in two feeding dishes with different target strength, and determined the reduction rate for the emission SPL and the increase rate for the SPL of the returning echoes. When approaching the dish with higher target strength bats started the reduction of the emission SPL at a larger reaction distance (1.05 ± 0.21 m) and approached it with a lower reduction rate of 7.2 dB/halving of distance (hd), thus producing a change of echo rate at the ears of + 4 dB/hd. At the weaker target reaction distance was shorter (0.71 ± 0.24 m) and the reduction rate (9.1 dB/hd) was higher, producing a change of echo rate of-1.2 dB/hd. Independent of dish type, bats lowered the emission SPL by about 26 dB on average. In one bat where the echo SPL from both targets could be measured, the reduction of emission SPL was triggered when the echo SPL surpassed a similar threshold value around 41-42 dB. Echo SPL was not adjusted at a constant value indicating that Myotis myotis and most likely all other bats do not use a closed loop system for intensity compensation when approaching a target of interest. We propose that bats lower the emission SPL to adjust the SPL of the perceived pulse-echo-pairs to the optimal auditory range for the processing of range information and hypothesize that bats use flow field information not only to control the reduction of the approach speed to the target but also to control the reduction of emission SPL.

Stereotypical rapid source level regulation in the harbour porpoise biosonar.

PubMed

Linnenschmidt, Meike; Kloepper, Laura N; Wahlberg, Magnus; Nachtigall, Paul E

2012-09-01

Some odontocetes and bats vary both click intensity and receiver sensitivity during echolocation, depending on target range. It is not known how this so-called automatic gain control is regulated by the animal. The source level of consecutive echolocation clicks from a harbour porpoise was measured with a hydrophone array while the animal detected an aluminium cylinder at 2, 4 or 8 m distance in a go/no-go paradigm. On-axis clicks had source levels of 145-174 dB re 1 μPa peak-to-peak. During target-present trials the click trains reached comparable source levels independent of the range to the target after three clicks. After an additional click, the source level was reduced for the 2 and 4 m trials until it equalled the one-way transmission loss. During target-absent trials, the source level remained high throughout the entire click train. Given typical values of harbour porpoise inter-click intervals, the source level reduction commenced within a few 100 ms from the first click in the click train. This may indicate a sub-cortically regulated source level regulation in the harbour porpoise.

Sensory-based niche partitioning in a multiple predator - multiple prey community.

PubMed

Falk, Jay J; ter Hofstede, Hannah M; Jones, Patricia L; Dixon, Marjorie M; Faure, Paul A; Kalko, Elisabeth K V; Page, Rachel A

2015-06-07

Many predators and parasites eavesdrop on the communication signals of their prey. Eavesdropping is typically studied as dyadic predator-prey species interactions; yet in nature, most predators target multiple prey species and most prey must evade multiple predator species. The impact of predator communities on prey signal evolution is not well understood. Predators could converge in their preferences for conspicuous signal properties, generating competition among predators and natural selection on particular prey signal features. Alternatively, predator species could vary in their preferences for prey signal properties, resulting in sensory-based niche partitioning of prey resources. In the Neotropics, many substrate-gleaning bats use the mate-attraction songs of male katydids to locate them as prey. We studied mechanisms of niche partitioning in four substrate-gleaning bat species and found they are similar in morphology, echolocation signal design and prey-handling ability, but each species preferred different acoustic features of male song in 12 sympatric katydid species. This divergence in predator preference probably contributes to the coexistence of many substrate-gleaning bat species in the Neotropics, and the substantial diversity in the mate-attraction signals of katydids. Our results provide insight into how multiple eavesdropping predator species might influence prey signal evolution through sensory-based niche partitioning. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Optimal design of a smart post-buckled beam actuator using bat algorithm: simulations and experiments

NASA Astrophysics Data System (ADS)

Mallick, Rajnish; Ganguli, Ranjan; Kumar, Ravi

2017-05-01

The optimized design of a smart post-buckled beam actuator (PBA) is performed in this study. A smart material based piezoceramic stack actuator is used as a prime-mover to drive the buckled beam actuator. Piezoceramic actuators are high force, small displacement devices; they possess high energy density and have high bandwidth. In this study, bench top experiments are conducted to investigate the angular tip deflections due to the PBA. A new design of a linear-to-linear motion amplification device (LX-4) is developed to circumvent the small displacement handicap of piezoceramic stack actuators. LX-4 enhances the piezoceramic actuator mechanical leverage by a factor of four. The PBA model is based on dynamic elastic stability and is analyzed using the Mathieu-Hill equation. A formal optimization is carried out using a newly developed meta-heuristic nature inspired algorithm, named as the bat algorithm (BA). The BA utilizes the echolocation capability of bats. An optimized PBA in conjunction with LX-4 generates end rotations of the order of 15° at the output end. The optimized PBA design incurs less weight and induces large end rotations, which will be useful in development of various mechanical and aerospace devices, such as helicopter trailing edge flaps, micro and nano aerial vehicles and other robotic systems.

A biologically inspired approach to modeling unmanned vehicle teams

NASA Astrophysics Data System (ADS)

Cortesi, Roger S.; Galloway, Kevin S.; Justh, Eric W.

2008-04-01

Cooperative motion control of teams of agile unmanned vehicles presents modeling challenges at several levels. The "microscopic equations" describing individual vehicle dynamics and their interaction with the environment may be known fairly precisely, but are generally too complicated to yield qualitative insights at the level of multi-vehicle trajectory coordination. Interacting particle models are suitable for coordinating trajectories, but require care to ensure that individual vehicles are not driven in a "costly" manner. From the point of view of the cooperative motion controller, the individual vehicle autopilots serve to "shape" the microscopic equations, and we have been exploring the interplay between autopilots and cooperative motion controllers using a multivehicle hardware-in-the-loop simulator. Specifically, we seek refinements to interacting particle models in order to better describe observed behavior, without sacrificing qualitative understanding. A recent analogous example from biology involves introducing a fixed delay into a curvature-control-based feedback law for prey capture by an echolocating bat. This delay captures both neural processing time and the flight-dynamic response of the bat as it uses sensor-driven feedback. We propose a comparable approach for unmanned vehicle modeling; however, in contrast to the bat, with unmanned vehicles we have an additional freedom to modify the autopilot. Simulation results demonstrate the effectiveness of this biologically guided modeling approach.

The cost of assuming the life history of a host: acoustic startle in the parasitoid fly Ormia ochracea

PubMed Central

Rosen, M. J.; Levin, E. C.; Hoy, R. R.

2009-01-01

In the obligatory reproductive dependence of a parasite on its host, the parasite must trade the benefit of ‘outsourcing’ functions like reproduction for the risk of assuming hazards associated with the host. In the present study, we report behavioral adaptations of a parasitic fly, Ormia ochracea, that resemble those of its cricket hosts. Ormia females home in on the male cricket's songs and deposit larvae, which burrow into the cricket, feed and emerge to pupate. Because male crickets call at night, gravid female Ormia in search of hosts are subject to bat predation, in much the same way as female crickets are when responding to male song. We show that Ormia has evolved the same evasive behavior as have crickets: an acoustic startle response to bat-like ultrasound that manifests clearly only during flight. Furthermore, like crickets, Ormia has a sharp response boundary between the frequencies of song and bat cries, resembling categorical perception first described in the context of human speech. PMID:19946084

The cost of assuming the life history of a host: acoustic startle in the parasitoid fly Ormia ochracea.

PubMed

Rosen, M J; Levin, E C; Hoy, R R

2009-12-01

In the obligatory reproductive dependence of a parasite on its host, the parasite must trade the benefit of 'outsourcing' functions like reproduction for the risk of assuming hazards associated with the host. In the present study, we report behavioral adaptations of a parasitic fly, Ormia ochracea, that resemble those of its cricket hosts. Ormia females home in on the male cricket's songs and deposit larvae, which burrow into the cricket, feed and emerge to pupate. Because male crickets call at night, gravid female Ormia in search of hosts are subject to bat predation, in much the same way as female crickets are when responding to male song. We show that Ormia has evolved the same evasive behavior as have crickets: an acoustic startle response to bat-like ultrasound that manifests clearly only during flight. Furthermore, like crickets, Ormia has a sharp response boundary between the frequencies of song and bat cries, resembling categorical perception first described in the context of human speech.

A cellular automata based FPGA realization of a new metaheuristic bat-inspired algorithm

NASA Astrophysics Data System (ADS)

Progias, Pavlos; Amanatiadis, Angelos A.; Spataro, William; Trunfio, Giuseppe A.; Sirakoulis, Georgios Ch.

2016-10-01

Optimization algorithms are often inspired by processes occuring in nature, such as animal behavioral patterns. The main concern with implementing such algorithms in software is the large amounts of processing power they require. In contrast to software code, that can only perform calculations in a serial manner, an implementation in hardware, exploiting the inherent parallelism of single-purpose processors, can prove to be much more efficient both in speed and energy consumption. Furthermore, the use of Cellular Automata (CA) in such an implementation would be efficient both as a model for natural processes, as well as a computational paradigm implemented well on hardware. In this paper, we propose a VHDL implementation of a metaheuristic algorithm inspired by the echolocation behavior of bats. More specifically, the CA model is inspired by the metaheuristic algorithm proposed earlier in the literature, which could be considered at least as efficient than other existing optimization algorithms. The function of the FPGA implementation of our algorithm is explained in full detail and results of our simulations are also demonstrated.

Sex-dependent hemispheric asymmetries for processing frequency-modulated sounds in the primary auditory cortex of the mustached bat

PubMed Central

Washington, Stuart D.

2012-01-01

Species-specific vocalizations of mammals, including humans, contain slow and fast frequency modulations (FMs) as well as tone and noise bursts. In this study, we established sex-specific hemispheric differences in the tonal and FM response characteristics of neurons in the Doppler-shifted constant-frequency processing area in the mustached bat's primary auditory cortex (A1). We recorded single-unit cortical activity from the right and left A1 in awake bats in response to the presentation of tone bursts and linear FM sweeps that are contained within their echolocation and/or communication sounds. Peak response latencies to neurons' preferred or best FMs were significantly longer on the right compared with the left in both sexes, and in males this right-left difference was also present for the most excitatory tone burst. Based on peak response magnitudes, right hemispheric A1 neurons in males preferred low-rate, narrowband FMs, whereas those on the left were less selective, responding to FMs with a variety of rates and bandwidths. The distributions of parameters for best FMs in females were similar on the two sides. Together, our data provide the first strong physiological support of a sex-specific, spectrotemporal hemispheric asymmetry for the representation of tones and FMs in a nonhuman mammal. Specifically, our results demonstrate a left hemispheric bias in males for the representation of a diverse array of FMs differing in rate and bandwidth. We propose that these asymmetries underlie lateralized processing of communication sounds and are common to species as divergent as bats and humans. PMID:22649207

Lancet Dynamics in Greater Horseshoe Bats, Rhinolophus ferrumequinum

PubMed Central

He, Weikai; Pedersen, Scott C.; Gupta, Anupam K.; Simmons, James A.; Müller, Rolf

2015-01-01

Echolocating greater horseshoe bats (Rhinolophus ferrumequinum) emit their biosonar pulses nasally, through nostrils surrounded by fleshy appendages (‘noseleaves’) that diffract the outgoing ultrasonic waves. Movements of one noseleaf part, the lancet, were measured in live bats using two synchronized high speed video cameras with 3D stereo reconstruction, and synchronized with pulse emissions recorded by an ultrasonic microphone. During individual broadcasts, the lancet briefly flicks forward (flexion) and is then restored to its original position. This forward motion lasts tens of milliseconds and increases the curvature of the affected noseleaf surfaces. Approximately 90% of the maximum displacements occurred within the duration of individual pulses, with 70% occurring towards the end. Similar lancet motions were not observed between individual pulses in a sequence of broadcasts. Velocities of the lancet motion were too small to induce Doppler shifts of a biologically-meaningful magnitude, but the maximum displacements were significant in comparison with the overall size of the lancet and the ultrasonic wavelengths. Three finite element models were made from micro-CT scans of the noseleaf post mortem to investigate the acoustic effects of lancet displacement. The broadcast beam shapes were found to be altered substantially by the observed small lancet movements. These findings demonstrate that—in addition to the previously described motions of the anterior leaf and the pinna—horseshoe bat biosonar has a third degree of freedom for fast changes that can happen on the time scale of the emitted pulses or the returning echoes and could provide a dynamic mechanism for the encoding of sensory information. PMID:25853738

Perception of echo delay is disrupted by small temporal misalignment of echo harmonics in bat sonar

PubMed Central

Bates, Mary E.; Simmons, James A.

2011-01-01

Echolocating big brown bats emit ultrasonic frequency-modulated (FM) biosonar sounds containing two prominent downward-sweeping harmonics (FM1 and FM2) and perceive target distance from echo delay. In naturally occurring echoes, FM1 and FM2 are delayed by the same amount. Even though echoes from targets located off-axis or far away are lowpass filtered, which weakens FM2 relative to FM1, their delays remain the same. We show here that misalignment of FM2 with FM1 by only 2.6 μs is sufficient to significantly disrupt acuity, which then persists for larger misalignments up to 300 μs. However, when FM2 is eliminated entirely rather than just misaligned, acuity is effectively restored. For naturally occurring, lowpass-filtered echoes, neuronal responses to weakened FM2 are retarded relative to FM1 because of amplitude-latency trading, which misaligns the harmonics in the bat's internal auditory representations. Electronically delaying FM2 relative to FM1 mimics the retarded neuronal responses for FM2 relative to FM1 caused by amplitude-latency trading. Echoes with either electronically or physiologically misaligned harmonics are not perceived as having a clearly defined delay. This virtual collapse of delay acuity may suppress interference from off-axis or distant clutter through degradation of delay images for clutter in contrast to sharp images for nearer, frontal targets. PMID:21228198

Perception of echo delay is disrupted by small temporal misalignment of echo harmonics in bat sonar.

PubMed

Bates, Mary E; Simmons, James A

2011-02-01

Echolocating big brown bats emit ultrasonic frequency-modulated (FM) biosonar sounds containing two prominent downward-sweeping harmonics (FM1 and FM2) and perceive target distance from echo delay. In naturally occurring echoes, FM1 and FM2 are delayed by the same amount. Even though echoes from targets located off-axis or far away are lowpass filtered, which weakens FM2 relative to FM1, their delays remain the same. We show here that misalignment of FM2 with FM1 by only 2.6 μs is sufficient to significantly disrupt acuity, which then persists for larger misalignments up to 300 μs. However, when FM2 is eliminated entirely rather than just misaligned, acuity is effectively restored. For naturally occurring, lowpass-filtered echoes, neuronal responses to weakened FM2 are retarded relative to FM1 because of amplitude-latency trading, which misaligns the harmonics in the bat's internal auditory representations. Electronically delaying FM2 relative to FM1 mimics the retarded neuronal responses for FM2 relative to FM1 caused by amplitude-latency trading. Echoes with either electronically or physiologically misaligned harmonics are not perceived as having a clearly defined delay. This virtual collapse of delay acuity may suppress interference from off-axis or distant clutter through degradation of delay images for clutter in contrast to sharp images for nearer, frontal targets.

On the taxonomic status and distribution of African species of Otomops (Chiroptera: Molossidae).

PubMed

Patterson, Bruce D; Webala, Paul W; Bartonjo, Michael; Nziza, Julius; Dick, Carl W; Demos, Terrence C

2018-01-01

Free-tailed bats of the genus Otomops are poorly known, and most species are documented from a handful of widely scattered localities. Recently, two allopatric species of Otomops were recognized in continental Africa: Otomops martiensseni (Matschie, 1897) in southern, central and western Africa, and the new species O. harrisoni Ralph et al., 2015 in the northeast and in Yemen. We collected additional samples of Otomops in Kenya and Rwanda where the ranges of these taxa approach one another to clarify their geographic ranges and taxonomic status. Mitochondrial and nuclear intron sequences served to identify and delimit species; we also documented their echolocation call variation and ectoparasite complements. Otomops martiensseni , the southern African species, was documented in northern Kenya in Marsabit National Park. O. harrisoni , the northeastern African-Arabian species, was documented in southern Kenya and in a cave in Musanze District, Rwanda. Moreover, individuals of both species were found together at the Musanze cave, establishing them in precise spatial and temporal sympatry. Analyses of mitochondrial and nuclear loci identify no evidence of admixture between these forms, although available samples limit the power of this analysis. Echolocation call differences are also apparent among the three localities we analyzed. Three orders of insects and two families of mites are newly reported as ectoparasites of O. harrisoni. Our results corroborate species rank for O. harrisoni and establish a zone of potential geographic overlap with O. martiensseni spanning at least 800 km of latitude. The new records establish the species in sympatry in northern Rwanda and add an additional species to the bat faunas of both Kenya and Rwanda. Future studies are needed to understand Otomops roosting requirements and movements, thereby explaining the paucity of known colonies and yielding better estimates of their conservation status. The discovery of mixed roosting associations in Rwanda invites further investigation.

Keeping returns optimal: gain control exerted through sensitivity adjustments in the harbour porpoise auditory system

PubMed Central

Linnenschmidt, Meike; Beedholm, Kristian; Wahlberg, Magnus; Højer-Kristensen, Jakob; Nachtigall, Paul E.

2012-01-01

Animals that use echolocation (biosonar) listen to acoustic signals with a large range of intensities, because echo levels vary with the fourth power of the animal's distance to the target. In man-made sonar, engineers apply automatic gain control to stabilize the echo energy levels, thereby rendering them independent of distance to the target. Both toothed whales and bats vary the level of their echolocation clicks to compensate for the distance-related energy loss. By monitoring the auditory brainstem response (ABR) during a psychophysical task, we found that a harbour porpoise (Phocoena phocoena), in addition to adjusting the sound level of the outgoing signals up to 5.4 dB, also reduces its ABR threshold by 6 dB when the target distance doubles. This self-induced threshold shift increases the dynamic range of the biosonar system and compensates for half of the variation of energy that is caused by changes in the distance to the target. In combination with an increased source level as a function of target range, this helps the porpoise to maintain a stable echo-evoked ABR amplitude irrespective of target range, and is therefore probably an important tool enabling porpoises to efficiently analyse and classify received echoes. PMID:22279169

The Origin of High-Frequency Hearing in Whales.

PubMed

Churchill, Morgan; Martinez-Caceres, Manuel; de Muizon, Christian; Mnieckowski, Jessica; Geisler, Jonathan H

2016-08-22

Odontocetes (toothed whales) rely upon echoes of their own vocalizations to navigate and find prey underwater [1]. This sensory adaptation, known as echolocation, operates most effectively when using high frequencies, and odontocetes are rivaled only by bats in their ability to perceive ultrasonic sound greater than 100 kHz [2]. Although features indicative of ultrasonic hearing are present in the oldest known odontocetes [3], the significance of this finding is limited by the methods employed and taxa sampled. In this report, we describe a new xenorophid whale (Echovenator sandersi, gen. et sp. nov.) from the Oligocene of South Carolina that, as a member of the most basal clade of odontocetes, sheds considerable light on the evolution of ultrasonic hearing. By placing high-resolution CT data from Echovenator sandersi, 2 hippos, and 23 fossil and extant whales in a phylogenetic context, we conclude that ultrasonic hearing, albeit in a less specialized form, evolved at the base of the odontocete radiation. Contrary to the hypothesis that odontocetes evolved from low-frequency specialists [4], we find evidence that stem cetaceans, the archaeocetes, were more sensitive to high-frequency sound than their terrestrial ancestors. This indicates that selection for high-frequency hearing predates the emergence of Odontoceti and the evolution of echolocation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Old World frog and bird vocalizations contain prominent ultrasonic harmonics

NASA Astrophysics Data System (ADS)

Narins, Peter M.; Feng, Albert S.; Lin, Wenyu; Schnitzler, Hans-Ulrich; Denzinger, Annette; Suthers, Roderick A.; Xu, Chunhe

2004-02-01

Several groups of mammals such as bats, dolphins and whales are known to produce ultrasonic signals which are used for navigation and hunting by means of echolocation, as well as for communication. In contrast, frogs and birds produce sounds during night- and day-time hours that are audible to humans; their sounds are so pervasive that together with those of insects, they are considered the primary sounds of nature. Here we show that an Old World frog (Amolops tormotus) and an oscine songbird (Abroscopus albogularis) living near noisy streams reliably produce acoustic signals that contain prominent ultrasonic harmonics. Our findings provide the first evidence that anurans and passerines are capable of generating tonal ultrasonic call components and should stimulate the quest for additional ultrasonic species.

The noseleaf of Rhinolophus formosae focuses the Frequency Modulated (FM) component of the calls

PubMed Central

Vanderelst, Dieter; Lee, Ya-Fu; Geipel, Inga; Kalko, Elisabeth K. V.; Kuo, Yen-Min; Peremans, Herbert

2013-01-01

Bats of the family Rhinolophidae emit their echolocation calls through their nostrils and feature elaborate noseleaves shaping the directionality of the emissions. The calls of these bats consist of a long constant-frequency component preceded and/or followed by short frequency-modulated sweeps. While Rhinolophidae are known for their physiological specializations for processing the constant frequency part of the calls, previous evidence suggests that the noseleaves of these animals are tuned to the frequencies in the frequency modulated components of the calls. In this paper, we seek further support for this hypothesis by simulating the emission beam pattern of the bat Rhinolophus formosae. Filling the furrows of lancet and removing the basal lappets (i.e., two flaps on the noseleaf) we find that these conspicuous features of the noseleaf focus the emitted energy mostly for frequencies in the frequency-modulated components. Based on the assumption that this component of the call is used by the bats for ranging, we develop a qualitative model to assess the increase in performance due to the furrows and/or the lappets. The model confirms that both structures decrease the ambiguity in selecting relevant targets for ranging. The lappets and the furrows shape the emission beam for different spatial regions and frequency ranges. Therefore, we conclude that the presented evidence is in line with the hypothesis that different parts of the noseleaves of Rhinolophidae are tuned to different frequency ranges with at least some of the most conspicuous ones being tuned to the frequency modulated components of the calls—thus yielding strong evidence for the sensory importance of the component. PMID:23882226

The effect of call libraries and acoustic filters on the identification of bat echolocation.

PubMed

Clement, Matthew J; Murray, Kevin L; Solick, Donald I; Gruver, Jeffrey C

2014-09-01

Quantitative methods for species identification are commonly used in acoustic surveys for animals. While various identification models have been studied extensively, there has been little study of methods for selecting calls prior to modeling or methods for validating results after modeling. We obtained two call libraries with a combined 1556 pulse sequences from 11 North American bat species. We used four acoustic filters to automatically select and quantify bat calls from the combined library. For each filter, we trained a species identification model (a quadratic discriminant function analysis) and compared the classification ability of the models. In a separate analysis, we trained a classification model using just one call library. We then compared a conventional model assessment that used the training library against an alternative approach that used the second library. We found that filters differed in the share of known pulse sequences that were selected (68 to 96%), the share of non-bat noises that were excluded (37 to 100%), their measurement of various pulse parameters, and their overall correct classification rate (41% to 85%). Although the top two filters did not differ significantly in overall correct classification rate (85% and 83%), rates differed significantly for some bat species. In our assessment of call libraries, overall correct classification rates were significantly lower (15% to 23% lower) when tested on the second call library instead of the training library. Well-designed filters obviated the need for subjective and time-consuming manual selection of pulses. Accordingly, researchers should carefully design and test filters and include adequate descriptions in publications. Our results also indicate that it may not be possible to extend inferences about model accuracy beyond the training library. If so, the accuracy of acoustic-only surveys may be lower than commonly reported, which could affect ecological understanding or management decisions based on acoustic surveys.

The effect of call libraries and acoustic filters on the identification of bat echolocation

PubMed Central

Clement, Matthew J; Murray, Kevin L; Solick, Donald I; Gruver, Jeffrey C

2014-01-01

Quantitative methods for species identification are commonly used in acoustic surveys for animals. While various identification models have been studied extensively, there has been little study of methods for selecting calls prior to modeling or methods for validating results after modeling. We obtained two call libraries with a combined 1556 pulse sequences from 11 North American bat species. We used four acoustic filters to automatically select and quantify bat calls from the combined library. For each filter, we trained a species identification model (a quadratic discriminant function analysis) and compared the classification ability of the models. In a separate analysis, we trained a classification model using just one call library. We then compared a conventional model assessment that used the training library against an alternative approach that used the second library. We found that filters differed in the share of known pulse sequences that were selected (68 to 96%), the share of non-bat noises that were excluded (37 to 100%), their measurement of various pulse parameters, and their overall correct classification rate (41% to 85%). Although the top two filters did not differ significantly in overall correct classification rate (85% and 83%), rates differed significantly for some bat species. In our assessment of call libraries, overall correct classification rates were significantly lower (15% to 23% lower) when tested on the second call library instead of the training library. Well-designed filters obviated the need for subjective and time-consuming manual selection of pulses. Accordingly, researchers should carefully design and test filters and include adequate descriptions in publications. Our results also indicate that it may not be possible to extend inferences about model accuracy beyond the training library. If so, the accuracy of acoustic-only surveys may be lower than commonly reported, which could affect ecological understanding or management decisions based on acoustic surveys. PMID:25535563

Context-dependent flight speed: evidence for energetically optimal flight speed in the bat Pipistrellus kuhlii?

PubMed

Grodzinski, Uri; Spiegel, Orr; Korine, Carmi; Holderied, Marc W

2009-05-01

1. Understanding the causes and consequences of animal flight speed has long been a challenge in biology. Aerodynamic theory is used to predict the most economical flight speeds, minimizing energy expenditure either per distance (maximal range speed, Vmr) or per time (minimal power speed, Vmp). When foraging in flight, flight speed also affects prey encounter and energy intake rates. According to optimal flight speed theory, such effects may shift the energetically optimal foraging speed to above Vmp. 2. Therefore, we predicted that if energetic considerations indeed have a substantial effect on flight speed of aerial-hawking bats, they will use high speed (close to Vmr) to commute from their daily roost to the foraging sites, while a slower speed (but still above Vmp) will be preferred during foraging. To test these predictions, echolocation calls of commuting and foraging Pipistrellus kuhlii were recorded and their flight tracks were reconstructed using an acoustic flight path tracking system. 3. Confirming our qualitative prediction, commuting flight was found to be significantly faster than foraging flight (9.3 vs. 6.7 m s(-1)), even when controlling for its lower tortuosity. 4. In order to examine our quantitative prediction, we compared observed flight speeds with Vmp and Vmr values generated for the study population using two alternative aerodynamic models, based on mass and wing morphology variables measured from bats we captured while commuting. The Vmp and Vmr values generated by one of the models were much lower than our measured flight speed. According to the other model used, however, measured foraging flight was faster than Vmp and commuting flight slightly slower than Vmr, which is in agreement with the predictions of optimal flight speed theory. 5. Thus, the second aerodynamic model we used seems to be a reasonable predictor of the different flight speeds used by the bats while foraging and while commuting. This supports the hypothesis that bats fly at a context-dependent, energetically optimal flight speed.

The effect of call libraries and acoustic filters on the identification of bat echolocation

USGS Publications Warehouse

Clement, Matthew; Murray, Kevin L; Solick, Donald I; Gruver, Jeffrey C

2014-01-01

Quantitative methods for species identification are commonly used in acoustic surveys for animals. While various identification models have been studied extensively, there has been little study of methods for selecting calls prior to modeling or methods for validating results after modeling. We obtained two call libraries with a combined 1556 pulse sequences from 11 North American bat species. We used four acoustic filters to automatically select and quantify bat calls from the combined library. For each filter, we trained a species identification model (a quadratic discriminant function analysis) and compared the classification ability of the models. In a separate analysis, we trained a classification model using just one call library. We then compared a conventional model assessment that used the training library against an alternative approach that used the second library. We found that filters differed in the share of known pulse sequences that were selected (68 to 96%), the share of non-bat noises that were excluded (37 to 100%), their measurement of various pulse parameters, and their overall correct classification rate (41% to 85%). Although the top two filters did not differ significantly in overall correct classification rate (85% and 83%), rates differed significantly for some bat species. In our assessment of call libraries, overall correct classification rates were significantly lower (15% to 23% lower) when tested on the second call library instead of the training library. Well-designed filters obviated the need for subjective and time-consuming manual selection of pulses. Accordingly, researchers should carefully design and test filters and include adequate descriptions in publications. Our results also indicate that it may not be possible to extend inferences about model accuracy beyond the training library. If so, the accuracy of acoustic-only surveys may be lower than commonly reported, which could affect ecological understanding or management decisions based on acoustic surveys.

Social communication in bats.

PubMed

Chaverri, Gloriana; Ancillotto, Leonardo; Russo, Danilo

2018-05-15

Bats represent one of the most diverse mammalian orders, not only in terms of species numbers, but also in their ecology and life histories. Many species are known to use ephemeral and/or unpredictable resources that require substantial investment to find and defend, and also engage in social interactions, thus requiring significant levels of social coordination. To accomplish these tasks, bats must be able to communicate; there is now substantial evidence that demonstrates the complexity of bat communication and the varied ways in which bats solve some of the problems associated with their unique life histories. However, while the study of communication in bats is rapidly growing, it still lags behind other taxa. Here we provide a comprehensive overview of communication in bats, from the reasons why they communicate to the diversity and application of different signal modalities. The most widespread form of communication is the transmission of a signaller's characteristics, such as species identity, sex, individual identity, group membership, social status and body condition, and because many species of bats can rely little on vision due to their nocturnal lifestyles, it is assumed that sound and olfaction are particularly important signalling modes. For example, research suggests that secretions from specialized glands, often in combination with urine and saliva, are responsible for species recognition in several species. These olfactory signals may also convey information about sex and colony membership. Olfaction may be used in combination with sound, particularly in species that emit constant frequency (CF) echolocation calls, to recognize conspecifics from heterospecifics, yet their simple structure and high frequency do not allow much information of individual identity to be conveyed over long distances. By contrast, social calls may encode a larger number of cues of individual identity, and their lower frequencies increase their range of detection. Social calls are also known to deter predators, repel competitors from foraging patches, attract group mates to roost sites, coordinate foraging activities, and are used during courtship. In addition to sound, visual displays such as wing flapping or hovering may be used during courtship, and swarming around roost sites may serve as a visual cue of roost location. However, visual communication in bats still remains a poorly studied signal modality. Finally, the most common form of tactile communication known in bats is social grooming, which may be used to signal reproductive condition, but also to facilitate and strengthen cooperative interactions. Overall, this review demonstrates the rapid advances made in the study of bat social communication during recent years, and also identifies topics that require further study, particularly those that may allow us to understand adaptation to rapidly changing environmental conditions. © 2018 Cambridge Philosophical Society.

Stereotypy and variability of social calls among clustering female big-footed myotis (Myotis macrodactylus).

PubMed

Xiao, Yan-Hong; Wang, Lei; Hoyt, Joseph R; Jiang, Ting-Lei; Lin, Ai-Qing; Feng, Jiang

2018-03-18

Echolocating bats have developed advanced auditory perception systems, predominantly using acoustic signaling to communicate with each other. They can emit a diverse range of social calls in complex behavioral contexts. This study examined the vocal repertoire of five pregnant big-footed myotis bats (Myotis macrodactylus). In the process of clustering, the last individual to return to the colony (LI) emitted social calls that correlated with behavior, as recorded on a PC-based digital recorder. These last individuals could emit 10 simple monosyllabic and 27 complex multisyllabic types of calls, constituting four types of syllables. The social calls were composed of highly stereotyped syllables, hierarchically organized by a common set of syllables. However, intra-specific variation was also found in the number of syllables, syllable order and patterns of syllable repetition across call renditions. Data were obtained to characterize the significant individual differences that existed in the maximum frequency and duration of calls. Time taken to return to the roost was negatively associated with the diversity of social calls. Our findings indicate that variability in social calls may be an effective strategy taken by individuals during reintegration into clusters of female M. macrodactylus.

Low-cost synchronization of high-speed audio and video recordings in bio-acoustic experiments.

PubMed

Laurijssen, Dennis; Verreycken, Erik; Geipel, Inga; Daems, Walter; Peremans, Herbert; Steckel, Jan

2018-02-27

In this paper, we present a method for synchronizing high-speed audio and video recordings of bio-acoustic experiments. By embedding a random signal into the recorded video and audio data, robust synchronization of a diverse set of sensor streams can be performed without the need to keep detailed records. The synchronization can be performed using recording devices without dedicated synchronization inputs. We demonstrate the efficacy of the approach in two sets of experiments: behavioral experiments on different species of echolocating bats and the recordings of field crickets. We present the general operating principle of the synchronization method, discuss its synchronization strength and provide insights into how to construct such a device using off-the-shelf components. © 2018. Published by The Company of Biologists Ltd.

Application of ultrasonic sensor for measuring distances in robotics

NASA Astrophysics Data System (ADS)

Zhmud, V. A.; Kondratiev, N. O.; Kuznetsov, K. A.; Trubin, V. G.; Dimitrov, L. V.

2018-05-01

Ultrasonic sensors allow us to equip robots with a means of perceiving surrounding objects, an alternative to technical vision. Humanoid robots, like robots of other types, are, first, equipped with sensory systems similar to the senses of a human. However, this approach is not enough. All possible types and kinds of sensors should be used, including those that are similar to those of other animals and creations (in particular, echolocation in dolphins and bats), as well as sensors that have no analogues in the wild. This paper discusses the main issues that arise when working with the HC-SR04 ultrasound rangefinder based on the STM32VLDISCOVERY evaluation board. The characteristics of similar modules for comparison are given. A subroutine for working with the sensor is given.

Amazon river dolphins (Inia geoffrensis) use a high-frequency short-range biosonar.

PubMed

Ladegaard, Michael; Jensen, Frants Havmand; de Freitas, Mafalda; Ferreira da Silva, Vera Maria; Madsen, Peter Teglberg

2015-10-01

Toothed whales produce echolocation clicks with source parameters related to body size; however, it may be equally important to consider the influence of habitat, as suggested by studies on echolocating bats. A few toothed whale species have fully adapted to river systems, where sonar operation is likely to result in higher clutter and reverberation levels than those experienced by most toothed whales at sea because of the shallow water and dense vegetation. To test the hypothesis that habitat shapes the evolution of toothed whale biosonar parameters by promoting simpler auditory scenes to interpret in acoustically complex habitats, echolocation clicks of wild Amazon river dolphins were recorded using a vertical seven-hydrophone array. We identified 404 on-axis biosonar clicks having a mean SLpp of 190.3 ± 6.1 dB re. 1 µPa, mean SLEFD of 132.1 ± 6.0 dB re. 1 µPa(2)s, mean Fc of 101.2 ± 10.5 kHz, mean BWRMS of 29.3 ± 4.3 kHz and mean ICI of 35.1 ± 17.9 ms. Piston fit modelling resulted in an estimated half-power beamwidth of 10.2 deg (95% CI: 9.6-10.5 deg) and directivity index of 25.2 dB (95% CI: 24.9-25.7 dB). These results support the hypothesis that river-dwelling toothed whales operate their biosonars at lower amplitude and higher sampling rates than similar-sized marine species without sacrificing high directivity, in order to provide high update rates in acoustically complex habitats and simplify auditory scenes through reduced clutter and reverberation levels. We conclude that habitat, along with body size, is an important evolutionary driver of source parameters in toothed whale biosonars. © 2015. Published by The Company of Biologists Ltd.

Time-of-Day Effects on Metabolic and Clock-Related Adjustments to Cold.

PubMed

Machado, Frederico Sander Mansur; Zhang, Zhi; Su, Yan; de Goede, Paul; Jansen, Remi; Foppen, Ewout; Coimbra, Cândido Celso; Kalsbeek, Andries

2018-01-01

Daily cyclic changes in environmental conditions are key signals for anticipatory and adaptive adjustments of most living species, including mammals. Lower ambient temperature stimulates the thermogenic activity of brown adipose tissue (BAT) and skeletal muscle. Given that the molecular components of the endogenous biological clock interact with thermal and metabolic mechanisms directly involved in the defense of body temperature, the present study evaluated the differential homeostatic responses to a cold stimulus at distinct time-windows of the light/dark-cycle. Male Wistar rats were subjected to a single episode of 3 h cold ambient temperature (4°C) at one of 6 time-points starting at Zeitgeber Times 3, 7, 11, 15, 19, and 23. Metabolic rate, core body temperature, locomotor activity (LA), feeding, and drinking behaviors were recorded during control and cold conditions at each time-point. Immediately after the stimulus, rats were euthanized and both the soleus and BAT were collected for real-time PCR. During the light phase (i.e., inactive phase), cold exposure resulted in a slight hyperthermia ( p  < 0.001). Light phase cold exposure also increased metabolic rate and LA ( p  < 0.001). In addition, the prevalence of fat oxidative metabolism was attenuated during the inactive phase ( p  < 0.001). These metabolic changes were accompanied by time-of-day and tissue-specific changes in core clock gene expression, such as DBP ( p  < 0.0001) and REV-ERBα ( p  < 0.01) in the BAT and CLOCK ( p  < 0.05), PER2 ( p  < 0.05), CRY1 ( p  < 0.05), CRY2 ( p  < 0.01), and REV-ERBα ( p  < 0.05) in the soleus skeletal muscle. Moreover, genes involved in substrate oxidation and thermogenesis were affected in a time-of-day and tissue-specific manner by cold exposure. The time-of-day modulation of substrate mobilization and oxidation during cold exposure provides a clear example of the circadian modulation of physiological and metabolic responses. Interestingly, after cold exposure, time-of-day mostly affected circadian clock gene expression in the soleus muscle, despite comparable changes in LA over the light-dark-cycle. The current findings add further evidence for tissue-specific actions of the internal clock in different peripheral organs such as skeletal muscle and BAT.

Learning to echolocate in sighted people: a correlational study on attention, working memory and spatial abilities.

PubMed

Ekkel, M R; van Lier, R; Steenbergen, B

2017-03-01

Echolocation can be beneficial for the orientation and mobility of visually impaired people. Research has shown considerable individual differences for acquiring this skill. However, individual characteristics that affect the learning of echolocation are largely unknown. In the present study, we examined individual factors that are likely to affect learning to echolocate: sustained and divided attention, working memory, and spatial abilities. To that aim, sighted participants with normal hearing performed an echolocation task that was adapted from a previously reported size-discrimination task. In line with existing studies, we found large individual differences in echolocation ability. We also found indications that participants were able to improve their echolocation ability. Furthermore, we found a significant positive correlation between improvement in echolocation and sustained and divided attention, as measured in the PASAT. No significant correlations were found with our tests regarding working memory and spatial abilities. These findings may have implications for the development of guidelines for training echolocation that are tailored to the individual with a visual impairment.

Island bat diets: does it matter more who you are or where you live?

PubMed

Sedlock, Jodi L; Krüger, Frauke; Clare, Elizabeth L

2014-08-01

Differences in body size, echolocation call frequency and location may result in diet partitioning among bat species. Comparisons between island populations are one way to evaluate these competing hypotheses. We conducted a species-level diet analysis of three Rhinolophus and one Hipposideros species on the Philippine islands of Cebu, Bohol and Siquijor. We identified 655 prey (MOTUs) in the guano from 77 individual bats. There was a high degree of overlap among species' diets despite differences in body size and call frequency. For example, the diet of the 3 g-Hipposideros pygmaeus (mean CF = 102 kHz) exhibited a diet overlap higher than expected by chance with all three Rhinolophus species, even the 13 g-Rhinolophus inops (mean CF = 54 kHz). We observed more convergence in diet between Rhinolophus species and H. pygmaeus than between Rhinolophus species themselves, which may be explained by the broad diet of H. pygmaeus. There was less dietary overlap between Rhinolophus virgo from two islands than between R. virgo and congeners from Cebu. These data suggest that location causes convergence in diet, but specific species characteristics may drive niche specialization. The complex interplay between location and the perceptual ability of each species leads to a situation where simple explanations, for example body size, do not translate into predictable prey partitioning. In particular, our observations raise interesting questions about the foraging strategy and adaptability of the tiny H. pygmaeus. © 2014 John Wiley & Sons Ltd.

Specialization of the auditory system for the processing of bio-sonar information in the frequency domain: Mustached bats.

PubMed

Suga, Nobuo

2018-04-01

For echolocation, mustached bats emit velocity-sensitive orientation sounds (pulses) containing a constant-frequency component consisting of four harmonics (CF 1-4 ). They show unique behavior called Doppler-shift compensation for Doppler-shifted echoes and hunting behavior for frequency and amplitude modulated echoes from fluttering insects. Their peripheral auditory system is highly specialized for fine frequency analysis of CF 2 (∼61.0 kHz) and detecting echo CF 2 from fluttering insects. In their central auditory system, lateral inhibition occurring at multiple levels sharpens V-shaped frequency-tuning curves at the periphery and creates sharp spindle-shaped tuning curves and amplitude tuning. The large CF 2 -tuned area of the auditory cortex systematically represents the frequency and amplitude of CF 2 in a frequency-versus-amplitude map. "CF/CF" neurons are tuned to a specific combination of pulse CF 1 and Doppler-shifted echo CF 2 or 3 . They are tuned to specific velocities. CF/CF neurons cluster in the CC ("C" stands for CF) and DIF (dorsal intrafossa) areas of the auditory cortex. The CC area has the velocity map for Doppler imaging. The DIF area is particularly for Dopper imaging of other bats approaching in cruising flight. To optimize the processing of behaviorally relevant sounds, cortico-cortical interactions and corticofugal feedback modulate the frequency tuning of cortical and sub-cortical auditory neurons and cochlear hair cells through a neural net consisting of positive feedback associated with lateral inhibition. Copyright © 2018 Elsevier B.V. All rights reserved.

The Auditory Skills Necessary for Echolocation: A New Explanation.

ERIC Educational Resources Information Center

Carlson-Smith, C.; Wiener, W. R.

1996-01-01

This study employed an audiometric test battery with nine blindfolded undergraduate students to explore success factors in echolocation. Echolocation performance correlated significantly with several specific auditory measures. No relationship was found between high-frequency sensitivity and echolocation performance. (Author/PB)

The relative contribution of drift and selection to phenotypic divergence: A test case using the horseshoe bats Rhinolophus simulator and Rhinolophus swinnyi.

PubMed

Mutumi, Gregory L; Jacobs, David S; Winker, Henning

2017-06-01

Natural selection and drift can act on populations individually, simultaneously or in tandem and our understanding of phenotypic divergence depends on our ability to recognize the contribution of each. According to the quantitative theory of evolution, if an organism has diversified through neutral evolutionary processes (mutation and drift), variation of phenotypic characteristics between different geographic localities ( B ) should be directly proportional to the variation within localities ( W ), that is, B  ∝  W . Significant deviations from this null model imply that non-neutral forces such as natural selection are acting on a phenotype. We investigated the relative contributions of drift and selection to intraspecific diversity using southern African horseshoe bats as a test case. We characterized phenotypic diversity across the distributional range of Rhinolophus simulator ( n =  101) and Rhinolophus swinnyi ( n =  125) using several traits associated with flight and echolocation. Our results suggest that geographic variation in both species was predominantly caused by disruptive natural selection ( B was not directly proportional to W ). Evidence for correlated selection (co-selection) among traits further confirmed that our results were not compatible with drift. Selection rather than drift is likely the predominant evolutionary process shaping intraspecific variation in traits that strongly impact fitness.

Tympanal mechanics and neural responses in the ears of a noctuid moth

NASA Astrophysics Data System (ADS)

Ter Hofstede, Hannah M.; Goerlitz, Holger R.; Montealegre-Z, Fernando; Robert, Daniel; Holderied, Marc W.

2011-12-01

Ears evolved in many groups of moths to detect the echolocation calls of predatory bats. Although the neurophysiology of bat detection has been intensively studied in moths for decades, the relationship between sound-induced movement of the noctuid tympanic membrane and action potentials in the auditory sensory cells (A1 and A2) has received little attention. Using laser Doppler vibrometry, we measured the velocity and displacement of the tympanum in response to pure tone pulses for moths that were intact or prepared for neural recording. When recording from the auditory nerve, the displacement of the tympanum at the neural threshold remained constant across frequencies, whereas velocity varied with frequency. This suggests that the key biophysical parameter for triggering action potentials in the sensory cells of noctuid moths is tympanum displacement, not velocity. The validity of studies on the neurophysiology of moth hearing rests on the assumption that the dissection and recording procedures do not affect the biomechanics of the ear. There were no consistent differences in tympanal velocity or displacement when moths were intact or prepared for neural recordings for sound levels close to neural threshold, indicating that this and other neurophysiological studies provide good estimates of what intact moths hear at threshold.

Processing and representation of social communication sounds in the brainstem auditory system of bats

NASA Astrophysics Data System (ADS)

Pollak, George D.

2003-10-01

While bats are best known for their abilities to orient and capture prey via echolocation, they are also highly social animals who use a rich repertoire of species-specific sounds for social communication. This talk explores how communication signals are progressively transformed and represented in the ascending auditory system. One principal transformation that distinguishes the inferior colliculus from lower nuclei is a change from processing that emphasizes response homogeneity among the neuronal population in each lower nucleus, to one that emphasizes heterogeneity and selectivity in the inferior colliculus. Collicular neurons are selective in that each neuron fails to respond to some, or even all calls, even though those calls have energy that encroaches upon their excitatory response regions, and are heterogeneous since each collicular neuron responds to a different subset of calls. The transformation from homogeneity to heterogeneity may largely be a consequence of the difference in the ways that the various excitatory and inhibitory inputs distribute along frequency contours in lower nuclei compared to the inferior colliculus. One important consequence is that those features endow the population in the inferior colliculus with the ability to respond to any signal with a unique and pronounced spatiotemporal pattern of activity. [Work supported by NIH Grant No. DC 00268.

Acoustic Sensors for Air and Surface Navigation Applications

PubMed Central

Kapoor, Rohan; Ramasamy, Subramanian; Schyndel, Ron Van

2018-01-01

This paper presents the state-of-the-art and reviews the state-of-research of acoustic sensors used for a variety of navigation and guidance applications on air and surface vehicles. In particular, this paper focuses on echolocation, which is widely utilized in nature by certain mammals (e.g., cetaceans and bats). Although acoustic sensors have been extensively adopted in various engineering applications, their use in navigation and guidance systems is yet to be fully exploited. This technology has clear potential for applications in air and surface navigation/guidance for intelligent transport systems (ITS), especially considering air and surface operations indoors and in other environments where satellite positioning is not available. Propagation of sound in the atmosphere is discussed in detail, with all potential attenuation sources taken into account. The errors introduced in echolocation measurements due to Doppler, multipath and atmospheric effects are discussed, and an uncertainty analysis method is presented for ranging error budget prediction in acoustic navigation applications. Considering the design challenges associated with monostatic and multi-static sensor implementations and looking at the performance predictions for different possible configurations, acoustic sensors show clear promises in navigation, proximity sensing, as well as obstacle detection and tracking. The integration of acoustic sensors in multi-sensor navigation systems is also considered towards the end of the paper and a low Size, Weight and Power, and Cost (SWaP-C) sensor integration architecture is presented for possible introduction in air and surface navigation systems. PMID:29414894

Enhanced auditory spatial localization in blind echolocators.

PubMed

Vercillo, Tiziana; Milne, Jennifer L; Gori, Monica; Goodale, Melvyn A

2015-01-01

Echolocation is the extraordinary ability to represent the external environment by using reflected sound waves from self-generated auditory pulses. Blind human expert echolocators show extremely precise spatial acuity and high accuracy in determining the shape and motion of objects by using echoes. In the current study, we investigated whether or not the use of echolocation would improve the representation of auditory space, which is severely compromised in congenitally blind individuals (Gori et al., 2014). The performance of three blind expert echolocators was compared to that of 6 blind non-echolocators and 11 sighted participants. Two tasks were performed: (1) a space bisection task in which participants judged whether the second of a sequence of three sounds was closer in space to the first or the third sound and (2) a minimum audible angle task in which participants reported which of two sounds presented successively was located more to the right. The blind non-echolocating group showed a severe impairment only in the space bisection task compared to the sighted group. Remarkably, the three blind expert echolocators performed both spatial tasks with similar or even better precision and accuracy than the sighted group. These results suggest that echolocation may improve the general sense of auditory space, most likely through a process of sensory calibration. Copyright © 2014 Elsevier Ltd. All rights reserved.

A computational model for biosonar echoes from foliage

PubMed Central

Gupta, Anupam Kumar; Lu, Ruijin; Zhu, Hongxiao

2017-01-01

Since many bat species thrive in densely vegetated habitats, echoes from foliage are likely to be of prime importance to the animals’ sensory ecology, be it as clutter that masks prey echoes or as sources of information about the environment. To better understand the characteristics of foliage echoes, a new model for the process that generates these signals has been developed. This model takes leaf size and orientation into account by representing the leaves as circular disks of varying diameter. The two added leaf parameters are of potential importance to the sensory ecology of bats, e.g., with respect to landmark recognition and flight guidance along vegetation contours. The full model is specified by a total of three parameters: leaf density, average leaf size, and average leaf orientation. It assumes that all leaf parameters are independently and identically distributed. Leaf positions were drawn from a uniform probability density function, sizes and orientations each from a Gaussian probability function. The model was found to reproduce the first-order amplitude statistics of measured example echoes and showed time-variant echo properties that depended on foliage parameters. Parameter estimation experiments using lasso regression have demonstrated that a single foliage parameter can be estimated with high accuracy if the other two parameters are known a priori. If only one parameter is known a priori, the other two can still be estimated, but with a reduced accuracy. Lasso regression did not support simultaneous estimation of all three parameters. Nevertheless, these results demonstrate that foliage echoes contain accessible information on foliage type and orientation that could play a role in supporting sensory tasks such as landmark identification and contour following in echolocating bats. PMID:28817631

A computational model for biosonar echoes from foliage.

PubMed

Ming, Chen; Gupta, Anupam Kumar; Lu, Ruijin; Zhu, Hongxiao; Müller, Rolf

2017-01-01

Since many bat species thrive in densely vegetated habitats, echoes from foliage are likely to be of prime importance to the animals' sensory ecology, be it as clutter that masks prey echoes or as sources of information about the environment. To better understand the characteristics of foliage echoes, a new model for the process that generates these signals has been developed. This model takes leaf size and orientation into account by representing the leaves as circular disks of varying diameter. The two added leaf parameters are of potential importance to the sensory ecology of bats, e.g., with respect to landmark recognition and flight guidance along vegetation contours. The full model is specified by a total of three parameters: leaf density, average leaf size, and average leaf orientation. It assumes that all leaf parameters are independently and identically distributed. Leaf positions were drawn from a uniform probability density function, sizes and orientations each from a Gaussian probability function. The model was found to reproduce the first-order amplitude statistics of measured example echoes and showed time-variant echo properties that depended on foliage parameters. Parameter estimation experiments using lasso regression have demonstrated that a single foliage parameter can be estimated with high accuracy if the other two parameters are known a priori. If only one parameter is known a priori, the other two can still be estimated, but with a reduced accuracy. Lasso regression did not support simultaneous estimation of all three parameters. Nevertheless, these results demonstrate that foliage echoes contain accessible information on foliage type and orientation that could play a role in supporting sensory tasks such as landmark identification and contour following in echolocating bats.

Unknown beaked whale echolocation signals recorded off eastern New Zealand.

PubMed

Giorli, Giacomo; Goetz, Kimberly T; Delarue, Julien; Maxner, Emily; Kowarski, Katie A; Bruce Martin, Steven; McPherson, Craig

2018-04-01

The echolocation signals of most beaked whale species are still unknown. In fact, out of the 22 species comprising the family Ziphiidae, only the echolocation pulses for 7 species have been clearly described. This study describes two distinct beaked whale echolocation signals recorded in the Cook Strait region using passive acoustic technology. These signals differ from previously described Ziphiid species clicks. A description of the time-frequency characteristics of the two signals is provided. Understanding the characteristics of these signals is necessary to correctly identify species from their echolocation signals and enables future monitoring of beaked whales using passive acoustics techniques.

A blind human expert echolocator shows size constancy for objects perceived by echoes.

PubMed

Milne, Jennifer L; Anello, Mimma; Goodale, Melvyn A; Thaler, Lore

2015-01-01

Some blind humans make clicking noises with their mouth and use the reflected echoes to perceive objects and surfaces. This technique can operate as a crude substitute for vision, allowing human echolocators to perceive silent, distal objects. Here, we tested if echolocation would, like vision, show size constancy. To investigate this, we asked a blind expert echolocator (EE) to echolocate objects of different physical sizes presented at different distances. The EE consistently identified the true physical size of the objects independent of distance. In contrast, blind and blindfolded sighted controls did not show size constancy, even when encouraged to use mouth clicks, claps, or other signals. These findings suggest that size constancy is not a purely visual phenomenon, but that it can operate via an auditory-based substitute for vision, such as human echolocation.

Application of the Biosonar Measurement Tool (BMT) and Instrumented Mine Simulators (IMS) to Exploration of Dolphin Echolocation During Free-Swimming, Bottom-Object Searches

DTIC Science & Technology

2003-09-01

0-933957-31-9 311 Application of the Biosonar Measurement Tool (BMT) and Instrumented...dolphin biosonar (echolocation). Research work conducted by the Navy has addressed the characteristics of echolocation clicks, mechanisms of...information on dolphin echolocation that can be data mined for biosonar search strategies under real-world conditions. Results can be applied to the

Amazon river dolphins (Inia geoffrensis) modify biosonar output level and directivity during prey interception in the wild.

PubMed

Ladegaard, Michael; Jensen, Frants Havmand; Beedholm, Kristian; da Silva, Vera Maria Ferreira; Madsen, Peter Teglberg

2017-07-15

Toothed whales have evolved to live in extremely different habitats and yet they all rely strongly on echolocation for finding and catching prey. Such biosonar-based foraging involves distinct phases of searching for, approaching and capturing prey, where echolocating animals gradually adjust sonar output to actively shape the flow of sensory information. Measuring those outputs in absolute levels requires hydrophone arrays centred on the biosonar beam axis, but this has never been done for wild toothed whales approaching and capturing prey. Rather, field studies make the assumption that toothed whales will adjust their biosonar in the same manner to arrays as they will when approaching prey. To test this assumption, we recorded wild botos ( Inia geoffrensis ) as they approached and captured dead fish tethered to a hydrophone in front of a star-shaped seven-hydrophone array. We demonstrate that botos gradually decrease interclick intervals and output levels during prey approaches, using stronger adjustment magnitudes than predicted from previous boto array data. Prey interceptions are characterised by high click rates, but although botos buzz during prey capture, they do so at lower click rates than marine toothed whales, resulting in a much more gradual transition from approach phase to buzzing. We also demonstrate for the first time that wild toothed whales broaden biosonar beamwidth when closing in on prey, as is also seen in captive toothed whales and bats, thus resulting in a larger ensonified volume around the prey, probably aiding prey tracking by decreasing the risk of prey evading ensonification. © 2017. Published by The Company of Biologists Ltd.

A beam based method for target localization: inspiration from bats' directivity and binaural reception for ultrasonic sonar.

PubMed

Guarato, Francesco; Windmill, James; Gachagan, Anthony

2013-06-01

The process of echolocation is accomplished by bats partly using the beam profiles associated with their ear shapes that allow for discrimination between different echo directions. Indeed, knowledge of the emitted signal characteristic and measurement of the echo travel time from a target make it possible to compensate for attenuation due to distance, and to focus on filtering through the receivers' beam profiles by comparing received echoes to the original signal at all frequencies in the spectrum of interest. From this basis, a beam profile method to localize a target in three-dimensional space for an ultrasonic sensor system equipped with an emitter and two receivers is presented. Simulations were conducted with different noise levels, and only the contribution of the receivers' beam profiles was considered to estimate the orientation of the target with respect to the receivers. The beam pattern of the Phyllostomus discolor's ear was adopted as that of a receiver. Analyses of beam resolution and frequency ranges were conducted to enhance the accuracy of orientation estimates. The choice of appropriate resolution and frequency ranges guarantee that error mean values for most of the orientations are within [0.5°, 1.5°], even in noisy situations: Signal-to-noise ratio values considered in this work are 35 and 50 dB.

Depth dependent variation of the echolocation pulse rate of bottlenose dolphins (Tursiops truncatus).

PubMed

Simard, Peter; Hibbard, Ashley L; McCallister, Kimberly A; Frankel, Adam S; Zeddies, David G; Sisson, Geoffrey M; Gowans, Shannon; Forys, Elizabeth A; Mann, David A

2010-01-01

Trained odontocetes appear to have good control over the timing (pulse rate) of their echolocation clicks; however, there is comparatively little information about how free-ranging odontocetes modify their echolocation in relation to their environment. This study investigates echolocation pulse rate in 14 groups of free-ranging bottlenose dolphins (Tursiops truncatus) at a variety of depths (2.4-30.1 m) in the Gulf of Mexico. Linear regression models indicated a significant decrease in mean pulse rate with mean water depth. Pulse rates for most groups were multi-modal. Distance to target estimates were as high as 91.8 m, assuming that echolocation was produced at a maximal rate for the target distance. A 5.29-ms processing lag time was necessary to explain the pulse rate modes observed. Although echolocation is likely reverberation limited, these results support the hypotheses that free-ranging bottlenose dolphins in this area are adapting their echolocation signals for a variety of target detection and ranging purposes, and that the target distance is a function of water depth.

Instrumenting free-swimming dolphins echolocating in open water.

PubMed

Martin, Stephen W; Phillips, Michael; Bauer, Eric J; Moore, Patrick W; Houser, Dorian S

2005-04-01

Dolphins within the Navy Marine Mammal Program use echolocation to effectively locate underwater mines. They currently outperform manmade systems at similar tasks, particularly in cluttered environments and on buried targets. In hopes of improving manmade mine-hunting sonar systems, two instrumentation packages were developed to monitor free-swimming dolphin motion and echolocation during open-water target detection tasks. The biosonar measurement tool (BMT) is carried by a dolphin and monitors underwater position and attitude while simultaneously recording echolocation clicks and returning echoes through high-gain binaural receivers. The instrumented mine simulator (IMS) is a modified bottom target that monitors echolocation signals arriving at the target during ensonification. Dolphin subjects were trained to carry the BMT in open-bay bottom-object target searches in which the IMS could serve as a bottom object. The instrumentation provides detailed data that reveal hereto-unavailable information on the search strategies of free-swimming dolphins conducting open-water, bottom-object search tasks with echolocation.

Instrumenting free-swimming dolphins echolocating in open water

NASA Astrophysics Data System (ADS)

Martin, Stephen W.; Phillips, Michael; Bauer, Eric J.; Moore, Patrick W.; Houser, Dorian S.

2005-04-01

Dolphins within the Navy Marine Mammal Program use echolocation to effectively locate underwater mines. They currently outperform manmade systems at similar tasks, particularly in cluttered environments and on buried targets. In hopes of improving manmade mine-hunting sonar systems, two instrumentation packages were developed to monitor free-swimming dolphin motion and echolocation during open-water target detection tasks. The biosonar measurement tool (BMT) is carried by a dolphin and monitors underwater position and attitude while simultaneously recording echolocation clicks and returning echoes through high-gain binaural receivers. The instrumented mine simulator (IMS) is a modified bottom target that monitors echolocation signals arriving at the target during ensonification. Dolphin subjects were trained to carry the BMT in open-bay bottom-object target searches in which the IMS could serve as a bottom object. The instrumentation provides detailed data that reveal hereto-unavailable information on the search strategies of free-swimming dolphins conducting open-water, bottom-object search tasks with echolocation. .

Marine Mammals: Hearing and Echolocation at Coconut Island

DTIC Science & Technology

2012-09-30

1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Marine Mammals: Hearing and Echolocation at Coconut ...REPORT DATE 2012 2. REPORT TYPE N/A 3. DATES COVERED - 4. TITLE AND SUBTITLE Marine Mammals: Hearing and Echolocation at Coconut Island

A false killer whale adjusts its hearing when it echolocates.

PubMed

Nachtigall, Paul E; Supin, Alexander Y

2008-06-01

The use of auditory evoked potential (AEP) measurements has added considerably to knowledge of the hearing mechanisms of marine mammals. We have recently measured the hearing of a stranded infant Risso's dolphin, the audiograms of white-beaked dolphins temporarily caught and released, and the hearing of anaesthetized polar bears. Most small toothed whales echolocate and hear very high frequency sounds underwater. While much has previously been learned about the echolocation performance and characteristics of the outgoing signals of echolocating dolphins and small whales, the hearing processes occurring while these animals actively echolocate have not previously been examined. Working with a well-trained echolocating false killer whale (Pseudorca crassidens) wearing latex surface suction cup electrodes, we have measured echolocation hearing AEPs in response to outgoing echolocation clicks, returning echoes, and comparable simulated whale clicks and echoes in a variety of situations. We have found that: (1) the whale may hear her loud outgoing clicks and much quieter returning echoes at comparable levels, (2) the whale has protective mechanisms that dampen the intensity of her outgoing signals - she hears her outgoing signals at a level about 40 dB lower than similar signals presented directly in front of her, (3) when echo return levels are lowered either by making the targets smaller or by placing the targets farther away - without changing the levels of her outgoing signals - the hearing of these echoes remains at almost the same level, (4) if targets are made much smaller and harder to echolocate, the animal will modify what she hears of her outgoing signal - as if to heighten overall hearing sensitivity to keep the echo level hearable, (5) the animal has an active 'automatic gain control' mechanism in her hearing based on both forward masking that balances outgoing pulse intensity and time between pulse and echo, and active hearing control. Overall, hearing during echolocation appears to be a very active process.

Single-lobed frequency-dependent beam shape in an echolocating false killer whale (Pseudorca crassidens).

PubMed

Kloepper, Laura N; Nachtigall, Paul E; Quintos, Christopher; Vlachos, Stephanie A

2012-01-01

Recent studies indicate some odontocetes may produce echolocation beams with a dual-lobed vertical structure. The shape of the odontocete echolocation beam was further investigated in a false killer whale performing an echolocation discrimination task. Clicks were recorded with an array of 16 hydrophones and frequency-dependent amplitude plots were constructed to assess beam shape. The majority of the echolocation clicks were single-lobed in structure with most energy located between 20 and 80 kHz. These data indicate the false killer whale does not produce a dual-lobed structure, as has been shown in bottlenose dolphins, which may be a function of lowered frequencies in the emitted signal due to hearing loss. © 2012 Acoustical Society of America.

Discovery Learning in Autonomous Agents Using Genetic Algorithms

DTIC Science & Technology

1993-12-01

Meyer and Wilson (47). 65. Roitblat , H. L., et al. "Biomimetic Sonar Processing: Prom Dolphin Echoloc-Ation to Artificial Neural Networks." In Meyer and...34 In Meyer and Wilson (47). 65. Roitblat , H. L., et al. "Biomimetic Sonar Processing: From Dolphin Echolocation to Artificial Neural Networks." In

A new fossil species supports an early origin for toothed whale echolocation.

PubMed

Geisler, Jonathan H; Colbert, Matthew W; Carew, James L

2014-04-17

Odontocetes (toothed whales, dolphins and porpoises) hunt and navigate through dark and turbid aquatic environments using echolocation; a key adaptation that relies on the same principles as sonar. Among echolocating vertebrates, odontocetes are unique in producing high-frequency vocalizations at the phonic lips, a constriction in the nasal passages just beneath the blowhole, and then using air sinuses and the melon to modulate their transmission. All extant odontocetes seem to echolocate; however, exactly when and how this complex behaviour--and its underlying anatomy--evolved is largely unknown. Here we report an odontocete fossil, Oligocene in age (approximately 28 Myr ago), from South Carolina (Cotylocara macei, gen. et sp. nov.) that has several features suggestive of echolocation: a dense, thick and downturned rostrum; air sac fossae; cranial asymmetry; and exceptionally broad maxillae. Our phylogenetic analysis places Cotylocara in a basal clade of odontocetes, leading us to infer that a rudimentary form of echolocation evolved in the early Oligocene, shortly after odontocetes diverged from the ancestors of filter-feeding whales (mysticetes). This was followed by enlargement of the facial muscles that modulate echolocation calls, which in turn led to marked, convergent changes in skull shape in the ancestors of Cotylocara, and in the lineage leading to extant odontocetes.

Neural Correlates of Natural Human Echolocation in Early and Late Blind Echolocation Experts

PubMed Central

Thaler, Lore; Arnott, Stephen R.; Goodale, Melvyn A.

2011-01-01

Background A small number of blind people are adept at echolocating silent objects simply by producing mouth clicks and listening to the returning echoes. Yet the neural architecture underlying this type of aid-free human echolocation has not been investigated. To tackle this question, we recruited echolocation experts, one early- and one late-blind, and measured functional brain activity in each of them while they listened to their own echolocation sounds. Results When we compared brain activity for sounds that contained both clicks and the returning echoes with brain activity for control sounds that did not contain the echoes, but were otherwise acoustically matched, we found activity in calcarine cortex in both individuals. Importantly, for the same comparison, we did not observe a difference in activity in auditory cortex. In the early-blind, but not the late-blind participant, we also found that the calcarine activity was greater for echoes reflected from surfaces located in contralateral space. Finally, in both individuals, we found activation in middle temporal and nearby cortical regions when they listened to echoes reflected from moving targets. Conclusions These findings suggest that processing of click-echoes recruits brain regions typically devoted to vision rather than audition in both early and late blind echolocation experts. PMID:21633496

Dolphins can maintain vigilant behavior through echolocation for 15 days without interruption or cognitive impairment.

PubMed

Branstetter, Brian K; Finneran, James J; Fletcher, Elizabeth A; Weisman, Brian C; Ridgway, Sam H

2012-01-01

In dolphins, natural selection has developed unihemispheric sleep where alternating hemispheres of their brain stay awake. This allows dolphins to maintain consciousness in response to respiratory demands of the ocean. Unihemispheric sleep may also allow dolphins to maintain vigilant states over long periods of time. Because of the relatively poor visibility in the ocean, dolphins use echolocation to interrogate their environment. During echolocation, dolphin produce clicks and listen to returning echoes to determine the location and identity of objects. The extent to which individual dolphins are able to maintain continuous vigilance through this active sense is unknown. Here we show that dolphins may continuously echolocate and accurately report the presence of targets for at least 15 days without interruption. During a total of three sessions, each lasting five days, two dolphins maintained echolocation behaviors while successfully detecting and reporting targets. Overall performance was between 75 to 86% correct for one dolphin and 97 to 99% correct for a second dolphin. Both animals demonstrated diel patterns in echolocation behavior. A 15-day testing session with one dolphin resulted in near perfect performance with no significant decrement over time. Our results demonstrate that dolphins can continuously monitor their environment and maintain long-term vigilant behavior through echolocation.

People's Ability to Detect Objects Using Click-Based Echolocation: A Direct Comparison between Mouth-Clicks and Clicks Made by a Loudspeaker.

PubMed

Thaler, Lore; Castillo-Serrano, Josefina

2016-01-01

Echolocation is the ability to use reflected sound to obtain information about the spatial environment. Echolocation is an active process that requires both the production of the emission as well as the sensory processing of the resultant sound. Appreciating the general usefulness of echo-acoustic cues for people, in particular those with vision impairments, various devices have been built that exploit the principle of echolocation to obtain and provide information about the environment. It is common to all these devices that they do not require the person to make a sound. Instead, the device produces the emission autonomously and feeds a resultant sound back to the user. Here we tested if echolocation performance in a simple object detection task was affected by the use of a head-mounted loudspeaker as compared to active clicking. We found that 27 sighted participants new to echolocation did generally better when they used a loudspeaker as compared to mouth-clicks, and that two blind participants with experience in echolocation did equally well with mouth clicks and the speaker. Importantly, performance of sighted participants' was not statistically different from performance of blind experts when they used the speaker. Based on acoustic click data collected from a subset of our participants, those participants whose mouth clicks were more similar to the speaker clicks, and thus had higher peak frequencies and sound intensity, did better. We conclude that our results are encouraging for the consideration and development of assistive devices that exploit the principle of echolocation.

People’s Ability to Detect Objects Using Click-Based Echolocation: A Direct Comparison between Mouth-Clicks and Clicks Made by a Loudspeaker

PubMed Central

Thaler, Lore; Castillo-Serrano, Josefina

2016-01-01

Echolocation is the ability to use reflected sound to obtain information about the spatial environment. Echolocation is an active process that requires both the production of the emission as well as the sensory processing of the resultant sound. Appreciating the general usefulness of echo-acoustic cues for people, in particular those with vision impairments, various devices have been built that exploit the principle of echolocation to obtain and provide information about the environment. It is common to all these devices that they do not require the person to make a sound. Instead, the device produces the emission autonomously and feeds a resultant sound back to the user. Here we tested if echolocation performance in a simple object detection task was affected by the use of a head-mounted loudspeaker as compared to active clicking. We found that 27 sighted participants new to echolocation did generally better when they used a loudspeaker as compared to mouth-clicks, and that two blind participants with experience in echolocation did equally well with mouth clicks and the speaker. Importantly, performance of sighted participants’ was not statistically different from performance of blind experts when they used the speaker. Based on acoustic click data collected from a subset of our participants, those participants whose mouth clicks were more similar to the speaker clicks, and thus had higher peak frequencies and sound intensity, did better. We conclude that our results are encouraging for the consideration and development of assistive devices that exploit the principle of echolocation. PMID:27135407

Chirplet Wigner-Ville distribution for time-frequency representation and its application

NASA Astrophysics Data System (ADS)

Chen, G.; Chen, J.; Dong, G. M.

2013-12-01

This paper presents a Chirplet Wigner-Ville Distribution (CWVD) that is free for cross-term that usually occurs in Wigner-Ville distribution (WVD). By transforming the signal with frequency rotating operators, several mono-frequency signals without intermittent are obtained, WVD is applied to the rotated signals that is cross-term free, then some frequency shift operators corresponding to the rotating operator are utilized to relocate the signal‧s instantaneous frequencies (IFs). The operators‧ parameters come from the estimation of the IFs which are approached with a polynomial functions or spline functions. What is more, by analysis of error, the main factors for the performance of the novel method have been discovered and an effective signal extending method based on the IFs estimation has been developed to improve the energy concentration of WVD. The excellent performance of the novel method was manifested by applying it to estimate the IFs of some numerical signals and the echolocation signal emitted by the Large Brown Bat.

Echolocation versus echo suppression in humans

PubMed Central

Wallmeier, Ludwig; Geßele, Nikodemus; Wiegrebe, Lutz

2013-01-01

Several studies have shown that blind humans can gather spatial information through echolocation. However, when localizing sound sources, the precedence effect suppresses spatial information of echoes, and thereby conflicts with effective echolocation. This study investigates the interaction of echolocation and echo suppression in terms of discrimination suppression in virtual acoustic space. In the ‘Listening’ experiment, sighted subjects discriminated between positions of a single sound source, the leading or the lagging of two sources, respectively. In the ‘Echolocation’ experiment, the sources were replaced by reflectors. Here, the same subjects evaluated echoes generated in real time from self-produced vocalizations and thereby discriminated between positions of a single reflector, the leading or the lagging of two reflectors, respectively. Two key results were observed. First, sighted subjects can learn to discriminate positions of reflective surfaces echo-acoustically with accuracy comparable to sound source discrimination. Second, in the Listening experiment, the presence of the leading source affected discrimination of lagging sources much more than vice versa. In the Echolocation experiment, however, the presence of both the lead and the lag strongly affected discrimination. These data show that the classically described asymmetry in the perception of leading and lagging sounds is strongly diminished in an echolocation task. Additional control experiments showed that the effect is owing to both the direct sound of the vocalization that precedes the echoes and owing to the fact that the subjects actively vocalize in the echolocation task. PMID:23986105

The Effects of Attenuating Returning Echolocation Signals at the Lower Jaw of a Dolphin (Tursiops Truncatus)

DTIC Science & Technology

1991-06-01

echolocation signals are guided to the inner ear of odonto - relatively little loss of energy. The biochemical composition cete cetaceans via areas of fatty...pool, on the range of useful al. (1986), and others have provided evidence that odonto - energy in the emitted clicks. cete cetaceans emit echolocation

Active echolocation beam focusing in the false killer whale, Pseudorca crassidens.

PubMed

Kloepper, Laura N; Nachtigall, Paul E; Donahue, Megan J; Breese, Marlee

2012-04-15

The odontocete sound production system is highly complex and produces intense, directional signals that are thought to be focused by the melon and the air sacs. Because odontocete echolocation signals are variable and the emitted click frequency greatly affects the echolocation beam shape, investigations of beam focusing must account for frequency-related beam changes. In this study we tested whether the echolocation beam of a false killer whale changed depending on target difficulty and distance while also accounting for frequency-related changes in the echolocation beam. The data indicate that the false killer whale changes its beam size according to target distance and difficulty, which may be a strategy of maximizing the energy of the target echo. We propose that the animal is using a strategy of changing the focal region according to target distance and that this strategy is under active control.

Recovery cycle times of inferior colliculus neurons in the awake bat measured with spike counts and latencies

PubMed Central

Sayegh, Riziq; Aubie, Brandon; Fazel-Pour, Siavosh; Faure, Paul A.

2012-01-01

Neural responses in the mammalian auditory midbrain (inferior colliculus; IC) arise from complex interactions of synaptic excitation, inhibition, and intrinsic properties of the cell. Temporally selective duration-tuned neurons (DTNs) in the IC are hypothesized to arise through the convergence of excitatory and inhibitory synaptic inputs offset in time. Synaptic inhibition can be inferred from extracellular recordings by presenting pairs of pulses (paired tone stimulation) and comparing the evoked responses of the cell to each pulse. We obtained single unit recordings from the IC of the awake big brown bat (Eptesicus fuscus) and used paired tone stimulation to measure the recovery cycle times of DTNs and non-temporally selective auditory neurons. By systematically varying the interpulse interval (IPI) of the paired tone stimulus, we determined the minimum IPI required for a neuron's spike count or its spike latency (first- or last-spike latency) in response to the second tone to recover to within ≥50% of the cell's baseline count or to within 1 SD of it's baseline latency in response to the first tone. Recovery times of shortpass DTNs were significantly shorter than those of bandpass DTNs, and recovery times of bandpass DTNs were longer than allpass neurons not selective for stimulus duration. Recovery times measured with spike counts were positively correlated with those measured with spike latencies. Recovery times were also correlated with first-spike latency (FSL). These findings, combined with previous studies on duration tuning in the IC, suggest that persistent inhibition is a defining characteristic of DTNs. Herein, we discuss measuring recovery times of neurons with spike counts and latencies. We also highlight how persistent inhibition could determine neural recovery times and serve as a potential mechanism underlying the precedence effect in humans. Finally, we explore implications of recovery times for DTNs in the context of bat hearing and echolocation. PMID:22933992

Four new bat species (Rhinolophus hildebrandtii complex) reflect Plio-Pleistocene divergence of dwarfs and giants across an Afromontane archipelago.

PubMed

Taylor, Peter J; Stoffberg, Samantha; Monadjem, Ara; Schoeman, Martinus Corrie; Bayliss, Julian; Cotterill, Fenton P D

2012-01-01

Gigantism and dwarfism evolve in vertebrates restricted to islands. We describe four new species in the Rhinolophus hildebrandtii species-complex of horseshoe bats, whose evolution has entailed adaptive shifts in body size. We postulate that vicissitudes of palaeoenvironments resulted in gigantism and dwarfism in habitat islands fragmented across eastern and southern Africa. Mitochondrial and nuclear DNA sequences recovered two clades of R. hildebrandtii senso lato which are paraphyletic with respect to a third lineage (R. eloquens). Lineages differ by 7.7 to 9.0% in cytochrome b sequences. Clade 1 includes R. hildebrandtii sensu stricto from the east African highlands and three additional vicariants that speciated across an Afromontane archipelago through the Plio-Pleistocene, extending from the Kenyan Highlands through the Eastern Arc, northern Mozambique and the Zambezi Escarpment to the eastern Great Escarpment of South Africa. Clade 2 comprises one species confined to lowland savanna habitats (Mozambique and Zimbabwe). A third clade comprises R. eloquens from East Africa. Speciation within Clade 1 is associated with fixed differences in echolocation call frequency, and cranial shape and size in populations isolated since the late Pliocene (ca 3.74 Mya). Relative to the intermediate-sized savanna population (Clade 2), these island-populations within Clade 1 are characterised by either gigantism (South African eastern Great Escarpment and Mts Mabu and Inago in Mozambique) or dwarfism (Lutope-Ngolangola Gorge, Zimbabwe and Soutpansberg Mountains, South Africa). Sympatry between divergent clades (Clade 1 and Clade 2) at Lutope-Ngolangola Gorge (NW Zimbabwe) is attributed to recent range expansions. We propose an "Allometric Speciation Hypothesis", which attributes the evolution of this species complex of bats to divergence in constant frequency (CF) sonar calls. The origin of species-specific peak frequencies (overall range = 32 to 46 kHz) represents the allometric effect of adaptive divergence in skull size, represented in the evolution of gigantism and dwarfism in habitat islands.

Four New Bat Species (Rhinolophus hildebrandtii Complex) Reflect Plio-Pleistocene Divergence of Dwarfs and Giants across an Afromontane Archipelago

PubMed Central

Taylor, Peter J.; Stoffberg, Samantha; Monadjem, Ara; Schoeman, Martinus Corrie; Bayliss, Julian; Cotterill, Fenton P. D.

2012-01-01

Gigantism and dwarfism evolve in vertebrates restricted to islands. We describe four new species in the Rhinolophus hildebrandtii species-complex of horseshoe bats, whose evolution has entailed adaptive shifts in body size. We postulate that vicissitudes of palaeoenvironments resulted in gigantism and dwarfism in habitat islands fragmented across eastern and southern Africa. Mitochondrial and nuclear DNA sequences recovered two clades of R. hildebrandtii senso lato which are paraphyletic with respect to a third lineage (R. eloquens). Lineages differ by 7.7 to 9.0% in cytochrome b sequences. Clade 1 includes R. hildebrandtii sensu stricto from the east African highlands and three additional vicariants that speciated across an Afromontane archipelago through the Plio-Pleistocene, extending from the Kenyan Highlands through the Eastern Arc, northern Mozambique and the Zambezi Escarpment to the eastern Great Escarpment of South Africa. Clade 2 comprises one species confined to lowland savanna habitats (Mozambique and Zimbabwe). A third clade comprises R. eloquens from East Africa. Speciation within Clade 1 is associated with fixed differences in echolocation call frequency, and cranial shape and size in populations isolated since the late Pliocene (ca 3.74 Mya). Relative to the intermediate-sized savanna population (Clade 2), these island-populations within Clade 1 are characterised by either gigantism (South African eastern Great Escarpment and Mts Mabu and Inago in Mozambique) or dwarfism (Lutope-Ngolangola Gorge, Zimbabwe and Soutpansberg Mountains, South Africa). Sympatry between divergent clades (Clade 1 and Clade 2) at Lutope-Ngolangola Gorge (NW Zimbabwe) is attributed to recent range expansions. We propose an “Allometric Speciation Hypothesis”, which attributes the evolution of this species complex of bats to divergence in constant frequency (CF) sonar calls. The origin of species-specific peak frequencies (overall range = 32 to 46 kHz) represents the allometric effect of adaptive divergence in skull size, represented in the evolution of gigantism and dwarfism in habitat islands. PMID:22984399

Echolocation behavior of franciscana dolphins (Pontoporia blainvillei) in the wild.

PubMed

Melcón, Mariana L; Failla, Mauricio; Iñíguez, Miguel A

2012-06-01

Franciscana dolphins are small odontocetes hard to study in the field. In particular, little is known on their echolocation behavior in the wild. In this study we recorded 357 min and analyzed 1019 echolocation signals in the Rio Negro Estuary, Argentina. The clicks had a peak frequency at 139 kHz, and a bandwidth of 19 kHz, ranging from 130 to 149 kHz. This is the first study describing echolocation signals of franciscana dolphins in the wild, showing the presence of narrow-band high frequency signals in these dolphins. Whether they use other vocalizations to communicate or not remains uncertain.

The size-weight illusion induced through human echolocation.

PubMed

Buckingham, Gavin; Milne, Jennifer L; Byrne, Caitlin M; Goodale, Melvyn A

2015-02-01

Certain blind individuals have learned to interpret the echoes of self-generated sounds to perceive the structure of objects in their environment. The current work examined how far the influence of this unique form of sensory substitution extends by testing whether echolocation-induced representations of object size could influence weight perception. A small group of echolocation experts made tongue clicks or finger snaps toward cubes of varying sizes and weights before lifting them. These echolocators experienced a robust size-weight illusion. This experiment provides the first demonstration of a sensory substitution technique whereby the substituted sense influences the conscious perception through an intact sense. © The Author(s) 2014.

Postnatal development of echolocation abilities in a bottlenose dolphin (Tursiops truncatus): temporal organization.

PubMed

Favaro, Livio; Gnone, Guido; Pessani, Daniela

2013-03-01

In spite of all the information available on adult bottlenose dolphin (Tursiops truncatus) biosonar, the ontogeny of its echolocation abilities has been investigated very little. Earlier studies have reported that neonatal dolphins can produce both whistles and burst-pulsed sounds just after birth and that early-pulsed sounds are probably a precursor of echolocation click trains. The aim of this research is to investigate the development of echolocation signals in a captive calf, born in the facilities of the Acquario di Genova. A set of 81 impulsive sounds were collected from birth to the seventh postnatal week and six additional echolocation click trains were recorded when the dolphin was 1 year old. Moreover, behavioral observations, concurring with sound production, were carried out by means of a video camera. For each sound we measured five acoustic parameters: click train duration (CTD), number of clicks per train, minimum, maximum, and mean click repetition rate (CRR). CTD and number of clicks per train were found to increase with age. Maximum and mean CRR followed a decreasing trend with dolphin growth starting from the second postnatal week. The calf's first head scanning movement was recorded 21 days after birth. Our data suggest that in the bottlenose dolphin the early postnatal weeks are essential for the development of echolocation abilities and that the temporal features of the echolocation click trains remain relatively stable from the seventh postnatal week up to the first year of life. © 2013 Wiley Periodicals, Inc.

Parahippocampal cortex is involved in material processing via echoes in blind echolocation experts.

PubMed

Milne, Jennifer L; Arnott, Stephen R; Kish, Daniel; Goodale, Melvyn A; Thaler, Lore

2015-04-01

Some blind humans use sound to navigate by emitting mouth-clicks and listening to the echoes that reflect from silent objects and surfaces in their surroundings. These echoes contain information about the size, shape, location, and material properties of objects. Here we present results from an fMRI experiment that investigated the neural activity underlying the processing of materials through echolocation. Three blind echolocation experts (as well as three blind and three sighted non-echolocating control participants) took part in the experiment. First, we made binaural sound recordings in the ears of each echolocator while he produced clicks in the presence of one of three different materials (fleece, synthetic foliage, or whiteboard), or while he made clicks in an empty room. During fMRI scanning these recordings were played back to participants. Remarkably, all participants were able to identify each of the three materials reliably, as well as the empty room. Furthermore, a whole brain analysis, in which we isolated the processing of just the reflected echoes, revealed a material-related increase in BOLD activation in a region of left parahippocampal cortex in the echolocating participants, but not in the blind or sighted control participants. Our results, in combination with previous findings about brain areas involved in material processing, are consistent with the idea that material processing by means of echolocation relies on a multi-modal material processing area in parahippocampal cortex. Copyright © 2014 Elsevier Ltd. All rights reserved.

Neurophysiological findings relevant to echolocation in marine animals

NASA Technical Reports Server (NTRS)

Bullock, T. H.; Ridgway, S. H.

1972-01-01

A review of echolocation mechanisms in marine mammals, chiefly porpoises, is given. Data cover peripheral auditory and central neurophysiological specializations favorable to the analysis of echolocating clicks and their echoes. Conclusions show (1) signals are received from 50 up to at least 135 kHz, (2) sound is received through the mandible skin, and (3) the midbrain sites are insensitive to low frequencies (below 6 kHz).

Blindness enhances auditory obstacle circumvention: Assessing echolocation, sensory substitution, and visual-based navigation

PubMed Central

Scarfe, Amy C.; Moore, Brian C. J.; Pardhan, Shahina

2017-01-01

Performance for an obstacle circumvention task was assessed under conditions of visual, auditory only (using echolocation) and tactile (using a sensory substitution device, SSD) guidance. A Vicon motion capture system was used to measure human movement kinematics objectively. Ten normally sighted participants, 8 blind non-echolocators, and 1 blind expert echolocator navigated around a 0.6 x 2 m obstacle that was varied in position across trials, at the midline of the participant or 25 cm to the right or left. Although visual guidance was the most effective, participants successfully circumvented the obstacle in the majority of trials under auditory or SSD guidance. Using audition, blind non-echolocators navigated more effectively than blindfolded sighted individuals with fewer collisions, lower movement times, fewer velocity corrections and greater obstacle detection ranges. The blind expert echolocator displayed performance similar to or better than that for the other groups using audition, but was comparable to that for the other groups using the SSD. The generally better performance of blind than of sighted participants is consistent with the perceptual enhancement hypothesis that individuals with severe visual deficits develop improved auditory abilities to compensate for visual loss, here shown by faster, more fluid, and more accurate navigation around obstacles using sound. PMID:28407000

Echolocation signals of foraging killer whales (Orcinus orca)

NASA Astrophysics Data System (ADS)

Au, Whitlow W. L.; Ford, John K. B.; Allman, Kelly A.

2002-05-01

Fish eating resident killer whales that frequent the coastal waters of Vancouver Island, Canada have a strong preference for chinook salmon. The whales in Johnston Strait often forage along the steep cliffs that extend into the water, echolocating their prey. Echolocation signals were measured with a four hydrophone symmetrical star array and the signals were simultaneous digitized at a sample rate of 500 kHz using a lunch-box PC. A portable VCR recorded the images from an underwater camera located close to the array center. Only signals emanated from close to the beam axis (1185 total) were chosen for a detailed analysis. Killer whales project very broad band echolocation signals (Q 1.3 to 1.5) that tend to have a bimodal frequency structure. Ninety seven percent of the signals had center frequencies between 45 and 80 kHz with a band-width between 35 and 50 kHz. The peak-to-peak source level of the echolocation signal decreased as a function of the one way transmission loss to the array. Source levels varied between 200 and 225 dB re 1 μPa. Using a model of target strength for chinook salmons, the echo levels from the echolocation signals are estimated for different ranges between whale and salmon.

Blindness enhances auditory obstacle circumvention: Assessing echolocation, sensory substitution, and visual-based navigation.

PubMed

Kolarik, Andrew J; Scarfe, Amy C; Moore, Brian C J; Pardhan, Shahina

2017-01-01

Performance for an obstacle circumvention task was assessed under conditions of visual, auditory only (using echolocation) and tactile (using a sensory substitution device, SSD) guidance. A Vicon motion capture system was used to measure human movement kinematics objectively. Ten normally sighted participants, 8 blind non-echolocators, and 1 blind expert echolocator navigated around a 0.6 x 2 m obstacle that was varied in position across trials, at the midline of the participant or 25 cm to the right or left. Although visual guidance was the most effective, participants successfully circumvented the obstacle in the majority of trials under auditory or SSD guidance. Using audition, blind non-echolocators navigated more effectively than blindfolded sighted individuals with fewer collisions, lower movement times, fewer velocity corrections and greater obstacle detection ranges. The blind expert echolocator displayed performance similar to or better than that for the other groups using audition, but was comparable to that for the other groups using the SSD. The generally better performance of blind than of sighted participants is consistent with the perceptual enhancement hypothesis that individuals with severe visual deficits develop improved auditory abilities to compensate for visual loss, here shown by faster, more fluid, and more accurate navigation around obstacles using sound.

Oilbirds produce echolocation signals beyond their best hearing range and adjust signal design to natural light conditions

PubMed Central

Brinkløv, Signe; Elemans, Coen P. H.

2017-01-01

Oilbirds are active at night, foraging for fruits using keen olfaction and extremely light-sensitive eyes, and echolocate as they leave and return to their cavernous roosts. We recorded the echolocation behaviour of wild oilbirds using a multi-microphone array as they entered and exited their roosts under different natural light conditions. During echolocation, the birds produced click bursts (CBs) lasting less than 10 ms and consisting of a variable number (2–8) of clicks at 2–3 ms intervals. The CBs have a bandwidth of 7–23 kHz at −6 dB from signal peak frequency. We report on two unique characteristics of this avian echolocation system. First, oilbirds reduce both the energy and number of clicks in their CBs under conditions of clear, moonlit skies, compared with dark, moonless nights. Second, we document a frequency mismatch between the reported best frequency of oilbird hearing (approx. 2 kHz) and the bandwidth of their echolocation CBs. This unusual signal-to-sensory system mismatch probably reflects avian constraints on high-frequency hearing but may still allow oilbirds fine-scale, close-range detail resolution at the upper extreme (approx. 10 kHz) of their presumed hearing range. Alternatively, oilbirds, by an as-yet unknown mechanism, are able to hear frequencies higher than currently appreciated. PMID:28573036

Change in echolocation signals with hearing loss in a false killer whale (Pseudorca crassidens).

PubMed

Kloepper, Laura N; Nachtigall, Paul E; Breese, Marlee

2010-10-01

The echolocation signals of a false killer whale (Pseudorca crassidens) were collected during a wall thickness discrimination task and compared to clicks recorded during an identical experiment in 1992. During the sixteen year time period, the subject demonstrated a loss of high frequency hearing of about 70 kHz. Clicks between the two experiments were compared to investigate the effect of hearing loss on echolocation signals. There was a significant reduction in the peak frequency, center frequency and source level of clicks between the two time periods. Additionally, the subject currently produces more signals with low frequency peaks and fewer signals with high frequency peaks than she did in 1992. These results indicate the subject changed its echolocation signals to match its range of best hearing.

Echolocation system of the bottlenose dolphin

NASA Astrophysics Data System (ADS)

Dubrovsky, N. A.

2004-05-01

The hypothesis put forward by Vel’min and Dubrovsky [1] is discussed. The hypothesis suggests that bottlenose dolphins possess two functionally separate auditory subsystems: one of them serves for analyzing extraneous sounds, as in nonecholocating terrestrial animals, and the other performs the analysis of echoes caused by the echolocation clicks of the animal itself. The first subsystem is called passive hearing, and the second, active hearing. The results of experimental studies of dolphin’s echolocation system are discussed to confirm the proposed hypothesis. For the active hearing of dolphins, the notion of a critical interval is considered as the interval of time within which the formation of a merged auditory image of the echolocation object is formed when all echo highlights of the echo from this object fall within the critical interval.

Scene analysis in the natural environment

PubMed Central

Lewicki, Michael S.; Olshausen, Bruno A.; Surlykke, Annemarie; Moss, Cynthia F.

2014-01-01

The problem of scene analysis has been studied in a number of different fields over the past decades. These studies have led to important insights into problems of scene analysis, but not all of these insights are widely appreciated, and there remain critical shortcomings in current approaches that hinder further progress. Here we take the view that scene analysis is a universal problem solved by all animals, and that we can gain new insight by studying the problems that animals face in complex natural environments. In particular, the jumping spider, songbird, echolocating bat, and electric fish, all exhibit behaviors that require robust solutions to scene analysis problems encountered in the natural environment. By examining the behaviors of these seemingly disparate animals, we emerge with a framework for studying scene analysis comprising four essential properties: (1) the ability to solve ill-posed problems, (2) the ability to integrate and store information across time and modality, (3) efficient recovery and representation of 3D scene structure, and (4) the use of optimal motor actions for acquiring information to progress toward behavioral goals. PMID:24744740

Listening to the environment: hearing differences from an epigenetic effect in solitarious and gregarious locusts.

PubMed

Gordon, Shira D; Jackson, Joseph C; Rogers, Stephen M; Windmill, James F C

2014-11-22

Locusts display a striking form of phenotypic plasticity, developing into either a lone-living solitarious phase or a swarming gregarious phase depending on population density. The two phases differ extensively in appearance, behaviour and physiology. We found that solitarious and gregarious locusts have clear differences in their hearing, both in their tympanal and neuronal responses. We identified significant differences in the shape of the tympana that may be responsible for the variations in hearing between locust phases. We measured the nanometre mechanical responses of the ear's tympanal membrane to sound, finding that solitarious animals exhibit greater displacement. Finally, neural experiments signified that solitarious locusts have a relatively stronger response to high frequencies. The enhanced response to high-frequency sounds in the nocturnally flying solitarious locusts suggests greater investment in detecting the ultrasonic echolocation calls of bats, to which they are more vulnerable than diurnally active gregarious locusts. This study highlights the importance of epigenetic effects set forth during development and begins to identify how animals are equipped to match their immediate environmental needs.

Decreased echolocation performance following high-frequency hearing loss in the false killer whale (Pseudorca crassidens).

PubMed

Kloepper, L N; Nachtigall, P E; Gisiner, R; Breese, M

2010-11-01

Toothed whales and dolphins possess a hypertrophied auditory system that allows for the production and hearing of ultrasonic signals. Although the fossil record provides information on the evolution of the auditory structures found in extant odontocetes, it cannot provide information on the evolutionary pressures leading to the hypertrophied auditory system. Investigating the effect of hearing loss may provide evidence for the reason for the development of high-frequency hearing in echolocating animals by demonstrating how high-frequency hearing assists in the functioning echolocation system. The discrimination abilities of a false killer whale (Pseudorca crassidens) were measured prior to and after documented high-frequency hearing loss. In 1992, the subject had good hearing and could hear at frequencies up to 100 kHz. In 2008, the subject had lost hearing at frequencies above 40 kHz. First in 1992, and then again in 2008, the subject performed an identical echolocation task, discriminating between machined hollow aluminum cylinder targets of differing wall thickness. Performances were recorded for individual target differences and compared between both experimental years. Performances on individual targets dropped between 1992 and 2008, with a maximum performance reduction of 36.1%. These data indicate that, with a loss in high-frequency hearing, there was a concomitant reduction in echolocation discrimination ability, and suggest that the development of a hypertrophied auditory system capable of hearing at ultrasonic frequencies evolved in response to pressures for fine-scale echolocation discrimination.

Dolphin hearing during echolocation: evoked potential responses in an Atlantic bottlenose dolphin (Tursiops truncatus).

PubMed

Li, Songhai; Nachtigall, Paul E; Breese, Marlee

2011-06-15

Auditory evoked potential (AEP) responses were recorded during echolocation in an Atlantic bottlenose dolphin (Tursiops truncatus) trained to accept suction-cup EEG electrodes and detect targets by echolocation. AEP recording was triggered by the echolocation clicks of the animal. Three targets with target strengths of -34, -28 and -22 dB were used at a target distance of 2 to 6.5 m for each target. The results demonstrated that the AEP appeared to both outgoing echolocation clicks and echoes during echolocation, with AEP complexes consisting of alternative positive and negative waves. The echo-related AEP amplitudes were obviously lower than the outgoing click-related AEP amplitudes for all the targets at the investigated target distances. However, for targets with target strengths of -22 and -28 dB, the peak-to-peak amplitudes of the echo-related AEPs were dependent on the target distances. The echo-related AEP response amplitudes increased at further target distances, demonstrating an overcompensation of echo attenuation with target distance in the echo-perception system of the dolphin biosonar. Measurement and analysis of outgoing click intensities showed that the click levels increased with target distance (R) by a factor of approximately 10 to 17.5 logR depending on target strength. The results demonstrated that a dual-component biosonar control system formed by intensity compensation behavior in both the transmission and receiving phases of a biosonar cycle exists synchronously in the dolphin biosonar system.

Dolphin "packet" use during long-range echolocation tasks.

PubMed

Finneran, James J

2013-03-01

When echolocating, dolphins typically emit a single broadband "click," then wait to receive the echo before emitting another click. However, previous studies have shown that during long-range echolocation tasks, they may instead emit a burst, or "packet," of several clicks, then wait for the packet of echoes to return before emitting another packet of clicks. The reasons for the use of packets are unknown. In this study, packet use was examined by having trained bottlenose dolphins perform long-range echolocation tasks. The tasks featured "phantom" echoes produced by capturing the dolphin's outgoing echolocation clicks, convolving the clicks with an impulse response to create an echo waveform, and then broadcasting the delayed, scaled echo to the dolphin. Dolphins were trained to report the presence of phantom echoes or a change in phantom echoes. Target range varied from 25 to 800 m. At ranges below 75 m, the dolphins rarely used packets. As the range increased beyond 75 m, two of the three dolphins increasingly produced packets, while the third dolphin instead utilized very high click repetition rates. The use of click packets appeared to be governed more by echo delay (target range) than echo amplitude.

Evoked potential application to study of echolocation in cetaceans

NASA Astrophysics Data System (ADS)

Supin, Alexander Ya.; Nactigall, Paul E.; Pawloski, Jeffrey; Au, Whitlow W. L.

2002-05-01

The evoked-potential (EP) method is effective in studies of hearing capabilities of cetaceans. However, until now EP studies in cetaceans were performed only in conditions of passive hearing by recording EP to external stimuli. Can this method be applied to study active echolocation in odontocetes? To answer this question, auditory brainstem evoked responses (ABR) were recorded in a false killer whale while the animal echolocated a target within an experiment in which the animal reported the target present or absent. The ABR collection was triggered by echolocation clicks. In these conditions, the recorded ABR pattern contained a duplicate set of waves. A comparison of ABR wave delays recorded during echolocation with those recorded during regular external stimulation has shown that the first set of waves is a response to the emitted click whereas the second one is a response to the echo. Both responses, to the emitted click and to the echo, were of comparable amplitude in spite of the intensity difference of these two sounds of more than 40 dB near the animal's head. This finding indicates some mechanisms releasing responses to echoes from masking by loud emitted clicks. The evoked-potential method may be productive to investigate these mechanisms.

Finite element simulation of broadband biosonar signal propagation in the near- and far-field of an echolocating Atlantic bottlenose dolphin (Tursiops truncatus).

PubMed

Wei, Chong; Au, Whitlow W L; Ketten, Darlene R; Zhang, Yu

2018-05-01

Bottlenose dolphins project broadband echolocation signals for detecting and locating prey and predators, and for spatial orientation. There are many unknowns concerning the specifics of biosonar signal production and propagation in the head of dolphins and this manuscript represents an effort to address this topic. A two-dimensional finite element model was constructed using high resolution CT scan data. The model simulated the acoustic processes in the vertical plane of the biosonar signal emitted from the phonic lips and propagated into the water through the animal's head. The acoustic field on the animal's forehead and the farfield transmission beam pattern of the echolocating dolphin were determined. The simulation results and prior acoustic measurements were qualitatively extremely consistent. The role of the main structures on the sound propagation pathway such as the air sacs, melon, and connective tissue was investigated. Furthermore, an investigation of the driving force at the phonic lips for dolphins that emit broadband echolocation signals and porpoises that emit narrowband echolocation signals suggested that the driving force is different for the two types of biosonar. Finally, the results provide a visual understanding of the sound transmission in dolphin's biosonar.

A dolphin lower jaw is a hydroacoustic antenna of the traveling wave

NASA Astrophysics Data System (ADS)

Ryabov, Vyacheslav A.

2003-10-01

The purpose of the work is the analysis of a possible function of mental foramens as channels through which the echo passes in the lower jaw fat body and the determination of a role of channels and a skull in formation of the directivity of the dolphin echolocation hearing. Concrete problems were studying of the lower jaw morphology, modeling and calculation of a dolphin, tursiops truncatus p., echolocation hearing beam pattern. The outcomes of the work indicate those morphological structures of the lower jaw; the left and right half represents two hydroacoustic receiving antennas of the traveling wave type, TWA farther. The mental foramens of a dolphin lower jaw represent nonequidistant array of waveguide delay lines, and determine the phase and amplitude distribution of each of the antenna's array. The beam pattern of the echolocation hearing was calculated with the usage of the TWA model, and the allowance of flat sound wave diffraction. The beam pattern shape is naturally determined by the echolocation hearing functionality. It is equally well adapted both for echolocation and for pulses echo detection. A steepness of the bearing characteristic is estimated; it reaches 0.7 dB per degree.

Vocal reporting of echolocation targets: dolphins often report before click trains end.

PubMed

Ridgway, S H; Elsberry, W R; Blackwood, D J; Kamolnick, T; Todd, M; Carder, D A; Chaplin, Monica; Cranford, T W

2012-01-01

Bottlenose dolphins (Tursiops truncatus) wore opaque suction cups over their eyes while stationing behind an acoustically opaque door. This put the dolphins in a known position and orientation. When the door opened, the dolphin clicked to detect targets. Trainers specified that Dolphin S emit a whistle if the target was a 7.5 cm water filled sphere, or a pulse burst if the target was a rock. S remained quiet if there was no target. Dolphin B whistled for the sphere. She remained quiet for rock and for no target. Thus, S had to choose between three different responses, whistle, pulse burst, or remain quiet. B had to choose between two different responses, whistle or remain quiet. S gave correct vocal responses averaging 114 ms after her last echolocation click (range 182 ms before and 219 ms after the last click). Average response for B was 21 ms before her last echolocation click (range 250 ms before and 95 ms after the last click in the train). More often than not, B began her whistle response before her echolocation train ended. The findings suggest separate neural pathways for generation of response vocalizations as opposed to echolocation clicks. © 2012 Acoustical Society of America.

Directional Selectivity for FM Sweeps in the Suprageniculate Nucleus of the Mustached Bat Medial Geniculate Body

PubMed Central

O’NEILL, WILLIAM E.; BRIMIJOIN, W. OWEN

2014-01-01

Mustached bats emit echolocation and communication calls containing both constant frequency (CF) and frequency-modulated (FM) components. Previously we found that 86% of neurons in the ventral division of the external nucleus of the inferior colliculus (ICXv) were directionally selective for linear FM sweeps and that selectivity was dependent on sweep rate. The ICXv projects to the suprageniculate nucleus (Sg) of the medial geniculate body. In this study, we isolated 37 single units in the Sg and measured their responses to best excitatory frequency (BEF) tones and linear 12-kHz upward and downward FM sweeps centered on the BEF. Sweeps were presented at durations of 30, 12, and 4 ms, yielding modulation rates of 400, 1,000, and 3,000 kHz/s. Spike count versus level functions were obtained at each modulation rate and compared with BEF controls. Sg units responded well to both tones and FM sweeps. BEFs clustered at 58 kHz, corresponding to the dominant CF component of the sonar signal. Spike count functions for both tones and sweeps were predominantly non-monotonic. FM directional selectivity was significant in 53–78% of the units, depending on modulation rate and level. Units were classified as up-selective (52%), down-selective (24%), or bi-directional (non-selective, 16%); a few units (8%) showed preferences that were either rate- or level-dependent. Most units showed consistent directional preferences at all SPLs and modulation rates tested, but typically showed stronger selectivity at lower sweep rates. Directional preferences were attributable to suppression of activity by sweeps in the non-preferred direction (~80% of units) and/or facilitation by sweeps in the preferred direction (~20–30%). Latencies for BEF tones ranged from 4.9 to 25.7 ms. Latencies for FM sweeps typically varied linearly with sweep duration. Most FM latency-duration functions had slopes ranging from 0.4 to 0.6, suggesting that the responses were triggered by the BEF. Latencies for BEF tones and FM sweeps were significantly correlated in most Sg units, i.e., the response to FM was temporally related to the occurrence of the BEF in the FM sweep. FM latency declined relative to BEF latency as modulation rate increased, suggesting that at higher rates response is triggered by frequencies in the sweep preceding the BEF. We conclude that Sg and ICXv units have similar, though not identical, response properties. Sg units are predominantly upsweep selective and could respond to either or both the CF and FM components in biosonar signals in a number of echolocation scenarios, as well as to a variety of communication sounds. PMID:12091543

Ranging in Human Sonar: Effects of Additional Early Reflections and Exploratory Head Movements

PubMed Central

Wallmeier, Ludwig; Wiegrebe, Lutz

2014-01-01

Many blind people rely on echoes from self-produced sounds to assess their environment. It has been shown that human subjects can use echolocation for directional localization and orientation in a room, but echo-acoustic distance perception - e.g. to determine one's position in a room - has received little scientific attention, and systematic studies on the influence of additional early reflections and exploratory head movements are lacking. This study investigates echo-acoustic distance discrimination in virtual echo-acoustic space, using the impulse responses of a real corridor. Six blindfolded sighted subjects and a blind echolocation expert had to discriminate between two positions in the virtual corridor, which differed by their distance to the front wall, but not to the lateral walls. To solve this task, participants evaluated echoes that were generated in real time from self-produced vocalizations. Across experimental conditions, we systematically varied the restrictions for head rotations, the subjects' orientation in virtual space and the reference position. Three key results were observed. First, all participants successfully solved the task with discrimination thresholds below 1 m for all reference distances (0.75–4 m). Performance was best for the smallest reference distance of 0.75 m, with thresholds around 20 cm. Second, distance discrimination performance was relatively robust against additional early reflections, compared to other echolocation tasks like directional localization. Third, free head rotations during echolocation can improve distance discrimination performance in complex environmental settings. However, head movements do not necessarily provide a benefit over static echolocation from an optimal single orientation. These results show that accurate distance discrimination through echolocation is possible over a wide range of reference distances and environmental conditions. This is an important functional benefit of human echolocation, which may also play a major role in the calibration of auditory space representations. PMID:25551226

Developing a Passive Acoustic Monitoring Network for Harbor Porpoise in California

NASA Astrophysics Data System (ADS)

Jacobson, Eiren Kate

Assessing the abundance of and trends in whale, dolphin, and porpoise (cetacean) populations using traditional visual methods can be challenging due primarily to their limited availability at the surface of the ocean. As a result, researchers are increasingly interested in incorporating non-visual and remote observations to improve cetacean population assessments. Passive acoustic monitoring (PAM) can complement or replace visual surveys for cetaceans that produce echolocation clicks, whistles, and other vocalizations. My doctoral dissertation is focused on developing methods to improve PAM of cetaceans. I used the Monterey Bay population of harbor porpoise (Phocoena phocoena ) as a case study for methods development. In Chapter 2, I used passive acoustic data to document that harbor porpoises avoid bottlenose dolphins (Tursiops truncatus) in nearshore Monterey Bay. In Chapter 3, I investigated whether different passive acoustic instruments could be used to monitor harbor porpoise. I recorded harbor porpoise echolocation clicks simultaneously on two different passive acoustic instruments and compared the number and peak frequency of echolocation signals recorded on the two instruments. I found that the number of echolocation clicks was highly correlated between instruments but that the peak frequency of echolocation clicks was not well-correlated, suggesting that some instruments may not be capable of discriminating harbor porpoise echolocation clicks in regions where multiple species with similar echolocation signals are present. In Chapter 4, I used paired visual and passive acoustic surveys to estimate the effective detection area of the passive acoustic sensors in a Bayesian framework. This approach resulted in a posterior distribution of the effective detection area that was consistent with previously published values. In Chapter 5, I used aerial survey and passive acoustic data in a simulation framework to investigate the statistical power of different passive acoustic network designs and hypothetical changes in harbor porpoise abundance. As a whole, this dissertation used an applied approach to methods development to advance the use of PAM for cetaceans.

Evoked potential recording during echolocation in a false killer whale Pseudorca crassidens (L)

NASA Astrophysics Data System (ADS)

Supin, Alexander Ya.; Nachtigall, Paul E.; Pawloski, Jeffrey; Au, Whitlow W. L.

2003-05-01

Auditory brainstem responses (ABRs) were recorded in a false killer whale while the animal echolocated a target. The ABR collection was triggered by echolocation clicks of the animal. In these conditions, the recorded ABR pattern contained a duplicate set of waves. A comparison of ABR wave delays recorded during echolocation with those recorded during regular external stimulation with experimenter generated clicks showed that the first set of waves may be a response to the emitted click whereas the second one may be a response to the echo. Both responses, to the emitted click and to the echo, were of comparable amplitude in spite of the intensity difference of these two sounds that may differ by more than 40 dB near the animal's head. This finding indicates the presence of some mechanism of releasing responses to echoes from masking by loud emitted clicks. The evoked-potential method may be productive to investigate these mechanisms.

Self-motion facilitates echo-acoustic orientation in humans

PubMed Central

Wallmeier, Ludwig; Wiegrebe, Lutz

2014-01-01

The ability of blind humans to navigate complex environments through echolocation has received rapidly increasing scientific interest. However, technical limitations have precluded a formal quantification of the interplay between echolocation and self-motion. Here, we use a novel virtual echo-acoustic space technique to formally quantify the influence of self-motion on echo-acoustic orientation. We show that both the vestibular and proprioceptive components of self-motion contribute significantly to successful echo-acoustic orientation in humans: specifically, our results show that vestibular input induced by whole-body self-motion resolves orientation-dependent biases in echo-acoustic cues. Fast head motions, relative to the body, provide additional proprioceptive cues which allow subjects to effectively assess echo-acoustic space referenced against the body orientation. These psychophysical findings clearly demonstrate that human echolocation is well suited to drive precise locomotor adjustments. Our data shed new light on the sensory–motor interactions, and on possible optimization strategies underlying echolocation in humans. PMID:26064556

Matching-to-sample by an echolocating dolphin (Tursiops truncatus).

PubMed

Roitblat, H L; Penner, R H; Nachtigall, P E

1990-01-01

An adult male dolphin was trained to perform a three-alternative delayed matching-to-sample task while wearing eyecups to occlude its vision. Sample and comparison stimuli consisted of a small and a large PVC plastic tube, a water-filled stainless steel sphere, and a solid aluminum cone. Stimuli were presented under water and the dolphin was allowed to identify the stimuli through echolocation. The echolocation clicks emitted by the dolphin to each sample and each comparison stimulus were recorded and analyzed. Over 48 sessions of testing, choice accuracy averaged 94.5% correct. This high level of accuracy was apparently achieved by varying the number of echolocation clicks emitted to various stimuli. Performance appeared to reflect a preexperimental stereotyped search pattern that dictated the order in which comparison items were examined and a complex sequential-sampling decision process. A model for the dolphin's decision-making processes is described.

Biosonar adjustments to target range of echolocating bottlenose dolphins (Tursiops sp.) in the wild.

PubMed

Jensen, F H; Bejder, L; Wahlberg, M; Madsen, P T

2009-04-01

Toothed whales use echolocation to locate and track prey. Most knowledge of toothed whale echolocation stems from studies on trained animals, and little is known about how toothed whales regulate and use their biosonar systems in the wild. Recent research suggests that an automatic gain control mechanism in delphinid biosonars adjusts the biosonar output to the one-way transmission loss to the target, possibly a consequence of pneumatic restrictions in how fast the sound generator can be actuated and still maintain high outputs. This study examines the relationships between target range (R), click intervals, and source levels of wild bottlenose dolphins (Tursiops sp.) by recording regular (non-buzz) echolocation clicks with a linear hydrophone array. Dolphins clicked faster with decreasing distance to the array, reflecting a decreasing delay between the outgoing echolocation click and the returning array echo. However, for interclick intervals longer than 30-40 ms, source levels were not limited by the repetition rate. Thus, pneumatic constraints in the sound-production apparatus cannot account for source level adjustments to range as a possible automatic gain control mechanism for target ranges longer than a few body lengths of the dolphin. Source level estimates drop with reducing range between the echolocating dolphins and the target as a function of 17 log(R). This may indicate either (1) an active form of time-varying gain in the biosonar independent of click intervals or (2) a bias in array recordings towards a 20 log(R) relationship for apparent source levels introduced by a threshold on received click levels included in the analysis.

Right-left asymmetry in the cortical processing of sounds for social communication vs. navigation in mustached bats.

PubMed

Kanwal, Jagmeet S

2012-01-01

In the Doppler-shifted constant frequency processing area in the primary auditory cortex of mustached bats, Pteronotus parnellii, neurons respond to both social calls and to echolocation signals. This multifunctional nature of cortical neurons creates a paradox for simultaneous processing of two behaviorally distinct categories of sound. To test the possibility of a stimulus-specific hemispheric bias, single-unit responses were obtained to both types of sounds, calls and pulse-echo tone pairs, from the right and left auditory cortex. Neurons on the left exhibited only slightly higher peak response magnitudes for their respective best calls, but they showed a significantly higher sensitivity (lower response thresholds) to calls than neurons on the right. On average, call-to-tone response ratios were significantly higher for neurons on the left than for those on the right. Neurons on the right responded significantly more strongly to pulse-echo tone pairs than those on the left. Overall, neurons in males responded to pulse-echo tone pairs with a much higher spike count compared to females, but this difference was less pronounced for calls. Multidimensional scaling of call responses yielded a segregated representation of call types only on the left. These data establish for the first time, a behaviorally directed right-left asymmetry at the level of single cortical neurons. It is proposed that a lateralized cortex emerges from multiparametric integration (e.g. combination-sensitivity) within a neuron and inhibitory interactions between neurons that come into play during the processing of complex sounds. © 2011 The Author. European Journal of Neuroscience © 2011 Federation of European Neuroscience Societies and Blackwell Publishing Ltd.

The interaction of outgoing echolocation pulses and echoes in the false killer whale's auditory system: Evoked-potential study

NASA Astrophysics Data System (ADS)

Supin, Alexander Ya.; Nachtigall, Paul E.; Au, Whitlow W. L.; Breese, Marlee

2004-06-01

Brain auditory evoked potentials (AEP) associated with echolocation were recorded in a false killer whale Pseudorca crassidens trained to accept suction-cup EEG electrodes and to detect targets by echolocation. AEP collection was triggered by echolocation pulses transmitted by the animal. The target was a hollow aluminum cylinder of strength of -22 dB at a distance from 1 to 8 m. Each AEP record was obtained by averaging more than 1000 individual records. All the records contained two AEP sets: the first one of a constant latency and a second one with a delay proportional to the distance. The timing of these two AEP sets was interpreted as responses to the transmitted echolocation pulse and echo, respectively. The echo-related AEP, although slightly smaller, was comparable to the outgoing click-related AEP in amplitude, even though at a target distance as far as 8 m the echo intensity was as low as -64 dB relative to the transmitted pulse in front of the head. The amplitude of the echo-related AEP was almost independent of distance, even though variation of target distance from 1 to 8 m influenced the echo intensity by as much as 36 dB.

The interaction of outgoing echolocation pulses and echoes in the false killer whale's auditory system: evoked-potential study.

PubMed

Supin, Alexander Ya; Nachtigall, Paul E; Au, Whitlow W L; Breese, Marlee

2004-06-01

Brain auditory evoked potentials (AEP) associated with echolocation were recorded in a false killer whale Pseudorca crassidens trained to accept suction-cup EEG electrodes and to detect targets by echolocation. AEP collection was triggered by echolocation pulses transmitted by the animal. The target was a hollow aluminum cylinder of strength of -22 dB at a distance from 1 to 8 m. Each AEP record was obtained by averaging more than 1000 individual records. All the records contained two AEP sets: the first one of a constant latency and a second one with a delay proportional to the distance. The timing of these two AEP sets was interpreted as responses to the transmitted echolocation pulse and echo, respectively. The echo-related AEP, although slightly smaller, was comparable to the outgoing click-related AEP in amplitude, even though at a target distance as far as 8 m the echo intensity was as low as -64 dB relative to the transmitted pulse in front of the head. The amplitude of the echo-related AEP was almost independent of distance, even though variation of target distance from 1 to 8 m influenced the echo intensity by as much as 36 dB.

Echolocation behaviour adapted to prey in foraging Blainville's beaked whale (Mesoplodon densirostris)

PubMed Central

Johnson, M; Hickmott, L.S; Aguilar Soto, N; Madsen, P.T

2007-01-01

Toothed whales echolocating in the wild generate clicks with low repetition rates to locate prey but then produce rapid sequences of clicks, called buzzes, when attempting to capture prey. However, little is known about the factors that determine clicking rates or how prey type and behaviour influence echolocation-based foraging. Here we study Blainville's beaked whales foraging in deep water using a multi-sensor DTAG that records both outgoing echolocation clicks and echoes returning from mesopelagic prey. We demonstrate that the clicking rate at the beginning of buzzes is related to the distance between whale and prey, supporting the presumption that whales focus on a specific prey target during the buzz. One whale showed a bimodal relationship between target range and clicking rate producing abnormally slow buzz clicks while attempting to capture large echoic targets, probably schooling prey, with echo duration indicating a school diameter of up to 4.3 m. These targets were only found when the whale performed tight circling manoeuvres spending up to five times longer in water volumes with large targets than with small targets. The result indicates that toothed whales in the wild can adjust their echolocation behaviour and movement for capture of different prey on the basis of structural echo information. PMID:17986434

Echolocation signals of free-ranging killer whales (Orcinus orca) and modeling of foraging for chinook salmon (Oncorhynchus tshawytscha)

NASA Astrophysics Data System (ADS)

Au, Whitlow W. L.; Ford, John K. B.; Horne, John K.; Allman, Kelly A. Newman

2004-02-01

Fish-eating ``resident''-type killer whales (Orcinus orca) that frequent the coastal waters off northeastern Vancouver Island, Canada have a strong preference for chinook salmon (Oncorhynchus tshawytscha). The whales in this region often forage along steep cliffs that extend into the water, echolocating their prey. Echolocation signals of resident killer whales were measured with a four-hydrophone symmetrical star array and the signals were simultaneously digitized at a sample rate of 500 kHz using a lunch-box PC. A portable VCR recorded the images from an underwater camera located adjacent to the array center. Only signals emanating from close to the beam axis (1185 total) were chosen for a detailed analysis. Killer whales project very broadband echolocation signals (Q equal 0.9 to 1.4) that tend to have bimodal frequency structure. Ninety-seven percent of the signals had center frequencies between 45 and 80 kHz with bandwidths between 35 and 50 kHz. The peak-to-peak source level of the echolocation signals decreased as a function of the one-way transmission loss to the array. Source levels varied between 195 and 224 dB re:1 μPa. Using a model of target strength for chinook salmon, the echo levels from the echolocation signals are estimated for different horizontal ranges between a whale and a salmon. At a horizontal range of 100 m, the echo level should exceed an Orcinus hearing threshold at 50 kHz by over 29 dB and should be greater than sea state 4 noise by at least 9 dB. In moderately heavy rain conditions, the detection range will be reduced substantially and the echo level at a horizontal range of 40 m would be close to the level of the rain noise.

Echolocation signals of free-ranging killer whales (Orcinus orca) and modeling of foraging for chinook salmon (Oncorhynchus tshawytscha).

PubMed

Au, Whitlow W L; Ford, John K B; Horne, John K; Allman, Kelly A Newman

2004-02-01

Fish-eating "resident"-type killer whales (Orcinus orca) that frequent the coastal waters off northeastern Vancouver Island, Canada have a strong preference for chinook salmon (Oncorhynchus tshawytscha). The whales in this region often forage along steep cliffs that extend into the water, echolocating their prey. Echolocation signals of resident killer whales were measured with a four-hydrophone symmetrical star array and the signals were simultaneously digitized at a sample rate of 500 kHz using a lunch-box PC. A portable VCR recorded the images from an underwater camera located adjacent to the array center. Only signals emanating from close to the beam axis (1185 total) were chosen for a detailed analysis. Killer whales project very broadband echolocation signals (Q equal 0.9 to 1.4) that tend to have bimodal frequency structure. Ninety-seven percent of the signals had center frequencies between 45 and 80 kHz with bandwidths between 35 and 50 kHz. The peak-to-peak source level of the echolocation signals decreased as a function of the one-way transmission loss to the array. Source levels varied between 195 and 224 dB re: 1 microPa. Using a model of target strength for chinook salmon, the echo levels from the echolocation signals are estimated for different horizontal ranges between a whale and a salmon. At a horizontal range of 100 m, the echo level should exceed an Orcinus hearing threshold at 50 kHz by over 29 dB and should be greater than sea state 4 noise by at least 9 dB. In moderately heavy rain conditions, the detection range will be reduced substantially and the echo level at a horizontal range of 40 m would be close to the level of the rain noise.

Baird's beaked whale echolocation signals.

PubMed

Baumann-Pickering, Simone; Yack, Tina M; Barlow, Jay; Wiggins, Sean M; Hildebrand, John A

2013-06-01

Echolocation signals from Baird's beaked whales were recorded during visual and acoustic shipboard surveys of cetaceans in the California Current ecosystem and with autonomous, long-term recorders in the Southern California Bight. The preliminary measurement of the visually validated Baird's beaked whale echolocation signals from towed array data were used as a basis for identifying Baird's signals in the autonomous recorder data. Two distinct signal types were found, one being a beaked whale-like frequency modulated (FM) pulse, the other being a dolphin-like broadband click. The median FM inter-pulse interval was 230 ms. Both signal types showed a consistent multi-peak structure in their spectra with peaks at ~9, 16, 25, and 40 kHz. Depending on signal type, as well as recording aspect and distance to the hydrophone, these peaks varied in relative amplitude. The description of Baird's echolocation signals will allow for studies of their distribution and abundance using towed array data without associated visual sightings and from autonomous seafloor hydrophones.

Male sperm whale acoustic behavior observed from multipaths at a single hydrophone

NASA Astrophysics Data System (ADS)

Laplanche, Christophe; Adam, Olivier; Lopatka, Maciej; Motsch, Jean-François

2005-10-01

Sperm whales generate transient sounds (clicks) when foraging. These clicks have been described as echolocation sounds, a result of having measured the source level and the directionality of these signals and having extrapolated results from biosonar tests made on some small odontocetes. The authors propose a passive acoustic technique requiring only one hydrophone to investigate the acoustic behavior of free-ranging sperm whales. They estimate whale pitch angles from the multipath distribution of click energy. They emphasize the close bond between the sperm whale's physical and acoustic activity, leading to the hypothesis that sperm whales might, like some small odontocetes, control click level and rhythm. An echolocation model estimating the range of the sperm whale's targets from the interclick interval is computed and tested during different stages of the whale's dive. Such a hypothesis on the echolocation process would indicate that sperm whales echolocate their prey layer when initiating their dives and follow a methodic technique when foraging.

Shared Midgut Binding Sites for Cry1A.105, Cry1Aa, Cry1Ab, Cry1Ac and Cry1Fa Proteins from Bacillus thuringiensis in Two Important Corn Pests, Ostrinia nubilalis and Spodoptera frugiperda

PubMed Central

Hernández-Rodríguez, Carmen Sara; Hernández-Martínez, Patricia; Van Rie, Jeroen; Escriche, Baltasar; Ferré, Juan

2013-01-01

First generation of insect-protected transgenic corn (Bt-corn) was based on the expression of Cry1Ab or Cry1Fa proteins. Currently, the trend is the combination of two or more genes expressing proteins that bind to different targets. In addition to broadening the spectrum of action, this strategy helps to delay the evolution of resistance in exposed insect populations. One of such examples is the combination of Cry1A.105 with Cry1Fa and Cry2Ab to control O. nubilalis and S. frugiperda. Cry1A.105 is a chimeric protein with domains I and II and the C-terminal half of the protein from Cry1Ac, and domain III almost identical to Cry1Fa. The aim of the present study was to determine whether the chimeric Cry1A.105 has shared binding sites either with Cry1A proteins, with Cry1Fa, or with both, in O. nubilalis and in S. frugiperda. Brush-border membrane vesicles (BBMV) from last instar larval midguts were used in competition binding assays with 125I-labeled Cry1A.105, Cry1Ab, and Cry1Fa, and unlabeled Cry1A.105, Cry1Aa, Cry1Ab, Cry1Ac, Cry1Fa, Cry2Ab and Cry2Ae. The results showed that Cry1A.105, Cry1Ab, Cry1Ac and Cry1Fa competed with high affinity for the same binding sites in both insect species. However, Cry2Ab and Cry2Ae did not compete for the binding sites of Cry1 proteins. Therefore, according to our results, the development of cross-resistance among Cry1Ab/Ac, Cry1A.105, and Cry1Fa proteins is possible in these two insect species if the alteration of shared binding sites occurs. Conversely, cross-resistance between these proteins and Cry2A proteins is very unlikely in such case. PMID:23861865

Bacillus thuringiensis delta-endotoxin binding to brush border membrane vesicles of rice stem borers.

PubMed

Alcantara, Edwin P; Aguda, Remedios M; Curtiss, April; Dean, Donald H; Cohen, Michael B

2004-04-01

The receptor binding step in the molecular mode of action of five delta-endotoxins (Cry1Ab, Cry1Ac, Cry1C, Cry2A, and Cry9C) from Bacillus thuringiensis was examined to find toxins with different receptor sites in the midgut of the striped stem borer (SSB) Chilo suppressalis (Walker) and yellow stem borer (YSB) Scirpophaga incertulas (Walker) (Lepidoptera: Pyralidae). Homologous competition assays were used to estimate binding affinities (K(com)) of (125)I-labelled toxins to brush border membrane vesicles (BBMV). The SSB BBMV affinities in decreasing order was: Cry1Ab = Cry1Ac > Cry9C > Cry2A > Cry1C. In YSB, the order of decreasing affinities was: Cry1Ac > Cry1Ab > Cry9C = Cry2A > Cry1C. The number of binding sites (B(max)) estimated by homologous competition binding among the Cry toxins did not affect toxin binding affinity (K(com)) to both insect midgut BBMVs. Results of the heterologous competition binding assays suggest that Cry1Ab and Cry1Ac compete for the same binding sites in SSB and YSB. Other toxins bind with weak (Cry1C, Cry2A) or no affinity (Cry9C) to Cry1Ab and Cry1Ac binding sites in both species. Cry2A had the lowest toxicity to 10-day-old SSB and Cry1Ab and Cry1Ac were the most toxic. Taken together, the results of this study show that Cry1Ab or Cry1Ac could be combined with either Cry1C, Cry2A, or Cry9C for more durable resistance in transgenic rice. Cry1Ab should not be used together with Cry1Ac because a mutation in one receptor site could diminish binding of both toxins. Copyright 2004 Wiley-Liss, Inc.

Recognition of aspect-dependent three-dimensional objects by an echolocating Atlantic bottlenose dolphin.

PubMed

Helweg, D A; Roitblat, H L; Nachtigall, P E; Hautus, M J

1996-01-01

We examined the ability of a bottlenose dolphin (Tursiops truncatus) to recognize aspect-dependent objects using echolocation. An aspect-dependent object such as a cube produces acoustically different echoes at different angles relative to the echolocation signal. The dolphin recognized the objects even though the objects were free to rotate and sway. A linear discriminant analysis and nearest centroid classifier could classify the objects using average amplitude, center frequency, and bandwidth of object echoes. The results show that dolphins can use varying acoustic properties to recognize constant objects and suggest that aspect-independent representations may be formed by combining information gleaned from multiple echoes.

Neuronal encoding of ultrasonic sound by a fish.

PubMed

Plachta, Dennis T T; Song, Jiakun; Halvorsen, Michele B; Popper, Arthur N

2004-06-01

Many species of odontocete cetaceans (toothed whales) use high-frequency clicks (60-170 kHz) to identify objects in their environment, including potential prey. Behavioral studies have shown that American shad, Alosa sapidissima, can detect ultrasonic signals similar to those of odontocetes that are potentially their predators. American shad also show strong escape behavior in response to ultrasonic pulses between 70 and 110 kHz and can determine the location of the sound source at least in the horizontal plane. The present study examines physiological aspects of ultrasound detection by American shad and provides the first insights into the neural encoding of ultrasound signals in any nonmammalian vertebrate. The recordings were obtained by penetration through the cerebellar surface. All but two units responded exclusively to ultrasound. Ultrasound-sensitive units did not phase-couple to any stimulus frequency. Some units resembled the response of constant latency neurons found in the ventral nucleus of the lateral lemniscus of bats. We suggest that ultrasonic and sonic signals are processed along different pathways in Alosa. The ultrasonic pathway in Alosa appears to be a feature detector that is likely to be adapted (e.g., frequency, intensity) to odontocete echolocation signals.

Screen of Bacillus thuringiensis toxins for transgenic rice to control Sesamia inferens and Chilo suppressalis.

PubMed

Gao, Yulin; Hu, Yang; Fu, Qiang; Zhang, Jie; Oppert, Brenda; Lai, Fengxiang; Peng, Yufa; Zhang, Zhitao

2010-09-01

Transgenic rice to control stem borer damage is under development in China. To assess the potential of Bacillus thuringiensis (Bt) transgenes in stem borer control, the toxicity of five Bt protoxins (Cry1Aa, Cry1Ab, Cry1Ac, Cry1Ba and Cry1Ca) against two rice stem borers, Sesamia inferens (pink stem borer) and Chilo suppressalis (striped stem borer), was evaluated in the laboratory by feeding neonate larvae on artificial diets containing Bt protoxins. The results indicated that Cry1Ca exhibited the highest level of toxicity to both stem borers, with an LC(50) of 0.24 and 0.30 microg/g for C. suppressalis and S. inferens, respectively. However, S. inferens was 4-fold lower in susceptibility to Cry1Aa, and 6- and 47-fold less susceptible to Cry1Ab and Cry1Ba, respectively, compared to C. suppressalis. To evaluate interactions among Bt protoxins in stem borer larvae, toxicity assays were performed with mixtures of Cry1Aa/Cry1Ab, Cry1Aa/Cry1Ca, Cry1Ac/Cry1Ca, Cry1Ac/Cry1Ba, Cry1Ab/Cry1Ac, Cry1Ab/Cry1Ba, and Cry1Ab/Cry1Ca at 1:1 (w/w) ratios. All protoxin mixtures demonstrated significant synergistic toxicity activity against C. suppressalis, with values of 1.6- to 11-fold higher toxicity than the theoretical additive effect. Surprisingly, all but one of the Bt protoxin mixtures were antagonistic in toxicity to S. inferens. In mortality-time response experiments, S. inferens demonstrated increased tolerance to Cry1Ab and Cry1Ac compared to C. suppressalis when treated with low or high protoxin concentrations. The data indicate the utility of Cry1Ca protoxin and a Cry1Ac/Cry1Ca mixture to control both stem borer populations. Copyright 2010 Elsevier Inc. All rights reserved.

The Use of Echolocation as a Mobility Aid for Blind Persons.

ERIC Educational Resources Information Center

Boehm, R.

1986-01-01

The value of echolocation for enhancing mobility of the blind was examined with five blind subjects and 11 sighted, blindfolded subjects. A hand held clicker provided the sounds for navigation through an unfamiliar hallway. Results indicated the blind subjects were better able to identify obstacles correctly using reflected sounds. (Author/DB)

Echolocation Reconsidered: Using Spatial Variations in the Ambient Sound Field To Guide Locomotion.

ERIC Educational Resources Information Center

Ashmead, Daniel H.; Wall, Robert S.; Eaton, Susan B.; Ebinger, Kiara A.; Snook-Hill, Mary-Maureen; And Others

1998-01-01

Presents an acoustical model and evidence from four experiments that children with visual impairments use the buildup of low-frequency sound along walls to guide locomotion. The model differs from the concept of echolocation by emphasizing sound that is ambient, rather than self-produced, and of low frequency. (Author/CR)

The energy ratio mapping algorithm: a tool to improve the energy-based detection of odontocete echolocation clicks.

PubMed

Klinck, Holger; Mellinger, David K

2011-04-01

The energy ratio mapping algorithm (ERMA) was developed to improve the performance of energy-based detection of odontocete echolocation clicks, especially for application in environments with limited computational power and energy such as acoustic gliders. ERMA systematically evaluates many frequency bands for energy ratio-based detection of echolocation clicks produced by a target species in the presence of the species mix in a given geographic area. To evaluate the performance of ERMA, a Teager-Kaiser energy operator was applied to the series of energy ratios as derived by ERMA. A noise-adaptive threshold was then applied to the Teager-Kaiser function to identify clicks in data sets. The method was tested for detecting clicks of Blainville's beaked whales while rejecting echolocation clicks of Risso's dolphins and pilot whales. Results showed that the ERMA-based detector correctly identified 81.6% of the beaked whale clicks in an extended evaluation data set. Average false-positive detection rate was 6.3% (3.4% for Risso's dolphins and 2.9% for pilot whales).

Spatial orientation of different frequencies within the echolocation beam of a Tursiops truncatus and Pseudorca crassidens.

PubMed

Ibsen, Stuart D; Nachtigall, Paul E; Krause-Nehring, Jacqueline; Kloepper, Laura; Breese, Marlee; Li, Songhai; Vlachos, Stephanie

2012-08-01

A two-dimensional array of 16 hydrophones was created to map the spatial distribution of different frequencies within the echolocation beam of a Tursiops truncatus and a Pseudorca crassidens. It was previously shown that both the Tursiops and Pseudorca only paid attention to frequencies between 29 and 42 kHz while echolocating. Both individuals tightly focused the 30 kHz frequency and the spatial location of the focus was consistently pointed toward the target. At 50 kHz the beam was less focused and less precisely pointed at the target. At 100 kHz the focus was often completely lost and was not pointed at the target. This indicates that these individuals actively focused the beam toward the target only in the frequency range they paid attention to. Frequencies outside this range were left unfocused and undirected. This focusing was probably achieved through sensorimotor control of the melon morphology and nasal air sacs. This indicates that both morphologically different species can control the spatial distribution of different frequency ranges within the echolocation beam to create consistent ensonation of desired targets.

Origin of the double- and multi-pulse structure of echolocation signals in Yangtze finless porpoise (Neophocaena phocaenoides asiaeorientialis)

NASA Astrophysics Data System (ADS)

Li, Songhai; Wang, Kexiong; Wang, Ding; Akamatsu, Tomonari

2005-12-01

The signals of dolphins and porpoises often exhibit a multi-pulse structure. Here, echolocation signal recordings were made from four geometrically distinct positions of seven Yangtze finless porpoises temporarily housed in a relatively small, enclosed area. Some clicks demonstrated double-pulse, and others multi-pulse, structure. The interpulse intervals between the first and second pulse of the double- and multi-pulse clicks were significantly different among data from the four different positions (p<0.01, one-way ANOVA). These results indicate that the interpulse interval and structure of the double- and multi-pulse echolocation signals depend on the hydrophone geometry of the animal, and that the double- and multi-pulse structure of echolocation signals in Yangtze finless porpoise is not caused by the phonating porpoise itself, but by the multipath propagation of the signal. Time delays in the 180° phase-shifted surface reflection pulse and the nonphase-shifted bottom reflection pulse of the multi-pulse structures, relative to the direct signal, can be used to calculate the distance to a phonating animal.

Efficacy of Genetically Modified Bt Toxins Alone and in Combinations Against Pink Bollworm Resistant to Cry1Ac and Cry2Ab

PubMed Central

Tabashnik, Bruce E.; Fabrick, Jeffrey A.; Unnithan, Gopalan C.; Yelich, Alex J.; Masson, Luke; Zhang, Jie; Bravo, Alejandra; Soberón, Mario

2013-01-01

Evolution of resistance in pests threatens the long-term efficacy of insecticidal proteins from Bacillus thuringiensis (Bt) used in sprays and transgenic crops. Previous work showed that genetically modified Bt toxins Cry1AbMod and Cry1AcMod effectively countered resistance to native Bt toxins Cry1Ab and Cry1Ac in some pests, including pink bollworm (Pectinophora gossypiella). Here we report that Cry1AbMod and Cry1AcMod were also effective against a laboratory-selected strain of pink bollworm resistant to Cry2Ab as well as to Cry1Ab and Cry1Ac. Resistance ratios based on the concentration of toxin killing 50% of larvae for the resistant strain relative to a susceptible strain were 210 for Cry2Ab, 270 for Cry1Ab, and 310 for Cry1Ac, but only 1.6 for Cry1AbMod and 2.1 for Cry1AcMod. To evaluate the interactions among toxins, we tested combinations of Cry1AbMod, Cry1Ac, and Cry2Ab. For both the resistant and susceptible strains, the net results across all concentrations tested showed slight but significant synergism between Cry1AbMod and Cry2Ab, whereas the other combinations of toxins did not show consistent synergism or antagonism. The results suggest that the modified toxins might be useful for controlling populations of pink bollworm resistant to Cry1Ac, Cry2Ab, or both. PMID:24244692

Target detection, shape discrimination, and signal characteristics of an echolocating false killer whale (Pseudorca crassidens).

PubMed

Brill, R L; Pawloski, J L; Helweg, D A; Au, W W; Moore, P W

1992-09-01

This study demonstrated the ability of a false killer whale (Pseudorca crassidens) to discriminate between two targets and investigated the parameters of the whale's emitted signals for changes related to test conditions. Target detection performance comparable to the bottlenose dolphin's (Tursiops truncatus) has previously been reported for echolocating false killer whales. No other echolocation capabilities have been reported. A false killer whale, naive to conditioned echolocation tasks, was initially trained to detect a cylinder in a "go/no-go" procedure over ranges of 3 to 8 m. The transition from a detection task to a discrimination task was readily achieved by introducing a spherical comparison target. Finally, the cylinder was successfully compared to spheres of two different sizes and target strengths. Multivariate analyses were used to evaluate the parameters of emitted signals. Duncan's multiple range tests showed significant decreases (df = 185, p less than 0.05) in both source level and bandwidth in the transition from detection to discrimination. Analysis of variance revealed a significant decrease in the number of clicks over test conditions [F(5.26) = 5.23, p less than 0.0001]. These data suggest that the whale relied on cues relevant to target shape as well as target strength, that changes in source level and bandwidth were task-related, that the decrease in clicks was associated with learning experience, and that Pseudorca's ability to discriminate shapes using echolocation may be comparable to that of Tursiops truncatus.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Yang; National Institute of Biological Sciences, Beijing 102206; Xiong, Wei

Although a deficiency in CRY1 or CRY2 correlates with a shorter or longer circadian period, the regulation of CRY proteins in the circadian period has not been well studied. In this study, we found that both CRY1 and CRY2 were able to rescue oscillation in CRY null cells and that they displayed different periods. Furthermore, we demonstrated that protein nuclear import rates, not protein stability, regulate the period-length at the cellular level. Co-transfection of CRY1 and CRY2 in various ratios in the same cells gives rise to the predicted period length in a dose-dependent manner. Given the distinct characteristics ofmore » the C-terminal tails of the CRY1 and CRY2 proteins, our study addresses a long-standing hypothesis that the ratio of these two CRY molecules affects the clock period. - Highlights: • Rhythmic CRY2, like CRY1, in the correct CRY1 phase is sufficient to rescue clock oscillation in CRY null cells. • The short-period mammalian CRY2 protein is more stable than the CRY1 protein. • The N-terminal polypeptide of CRY2 contributes to its stability and Per2 repression, but it does not affect the period. • The C-terminal tails of CRYs regulate their protein stability and nuclear import, but the import rate governs the period. • The ratio, rather than the absolute amounts of CRY1 and CRY2 proteins, determines the period in mammalian cells.« less

The beluga whale produces two pulses to form its sonar signal

PubMed Central

Lammers, Marc O.; Castellote, Manuel

2009-01-01

Odontocete cetaceans use biosonar clicks to acoustically probe their aquatic environment with an aptitude unmatched by man-made sonar. A cornerstone of this ability is their use of short, broadband pulses produced in the region of the upper nasal passages. Here we provide empirical evidence that a beluga whale (Delphinapterus leucas) uses two signal generators simultaneously when echolocating. We show that the pulses of the two generators are combined as they are transmitted through the melon to produce a single echolocation click emitted from the front of the animal. Generating two pulses probably offers the beluga the ability to control the energy and frequency distribution of the emitted click and may allow it to acoustically steer its echolocation beam. PMID:19324643

Toxin Gene Contents and Activity of Bacillus thuringiensis Strains Against Two Sugarcane Borer Species, Diatraea saccharalis (F.) and D. flavipennella (Box).

PubMed

Silva, L M; Silva, M C; Silva, S M F A; Alves, R C; Siqueira, H A A; Marques, E J

2018-04-01

Bacillus thuringiensis (Berliner) bears essential characteristics in the control of insect pests, such as its unique mode of action, which confers specificity and selectivity. This study assessed cry gene contents from Bt strains and their entomotoxicity against Diatraea saccharalis (F.) and Diatraea flavipennella (Box) (Lepidoptera: Crambidae). Bioassays with Bt strains were performed against neonates to evaluate their lethal and sublethal activities and were further analyzed by PCR, using primers to identify toxin genes. For D. saccharalis and D. flavipennella, 16 and 18 strains showed over 30% larval mortality in the 7th day, respectively. The LC 50 values of strains for D. saccharalis varied from 0.08 × 10 5 (LIIT-0105) to 4104 × 10 5 (LIIT-2707) spores + crystals mL -1 . For D. flavipennella, the LC 50 values of strains varied from 0.40 × 10 5 (LIIT-2707) to 542 × 10 5 (LIIT-2109) spores + crystals mL -1 . For the LIIT-0105 strain, which was the most toxic to D. saccharalis, the genes cry1Aa, cry1Ab, cry1Ac, cry1B, cry1C, cry1D, cry1F, cry1I, cry2Aa, cry2Ab, cry8, and cry9C were detected, whereas for the strain LIIT-2707, which was the most toxic to D. flavipennella, detected genes were cry1Aa, cry1Ab, cry1Ac, cry1B, cry1D, cry1F, cry1I, cry2Aa, cry2Ab, and cry9. The toxicity data and toxin gene content in these strains of Bt suggest a great variability of activity with potential to be used in the development of novel biopesticides or as source of resistance genes that can be expressed in plants to control pests.

Bt Proteins Have No Detrimental Effects on Larvae of the Green Lacewing, Chrysopa pallens (Rambur) (Neuroptera: Chrysopidae).

PubMed

Ali, I; Zhang, S; Muhammad, M S; Iqbal, M; Cui, J-J J-J

2018-06-01

Biosafety of a genetically modified crop is required to be assessed prior to its commercialization. For this, a suitable artificial diet was developed and used to establish a dietary exposure test for assessing the toxicity of midgut-active Bt insecticidal proteins on Chrysopa pallens (Rambur). Subsequently, this dietary exposure test was used to evaluate the toxicity of the proteins Cry1Ab, Cry1Ac, Cry1Ah, Cry1Ca, Cry1F, Cry2Aa, Cry2Ab, and Vip3Aa on C. pallens larvae. Temporal stability, bioactivity, and the intake of the insecticidal proteins were confirmed by enzyme-linked immunosorbent assay and a sensitive-insect bioassay. The life history characteristics, such as survival, pupation, adult emergence, 7-day larval weight, larval developmental time, and emerged male and female fresh weights remained unaffected, when C. pallens were fed the pure artificial diet (negative control) and the artificial diets containing 200 μg/g of each purified protein: Cry1Ab, Cry1Ac, Cry1Ah, Cry1Ca, Cry1F, Cry2Aa, Cry2Ab, or Vip3Aa. On the contrary, all of the life history characteristics of C. pallens larvae were adversely affected when fed artificial diet containing boric acid (positive control). The results demonstrate that diets containing the tested concentrations of Cry1Ab, Cry1Ac, Cry1Ah, Cry1Ca, Cry1F, Cry2Aa, Cry2Ab, and Vip3Aa have null effects on C. pallens larvae. The outcome indicates that genetically modified crops expressing the tested Bt proteins are safe for the lacewing, C. pallens.

Cross-resistance to purified Bt proteins, Bt corn and Bt cotton in a Cry2Ab2-corn resistant strain of Spodoptera frugiperda.

PubMed

Yang, Fei; Kerns, David L; Head, Graham P; Price, Paula; Huang, Fangneng

2017-12-01

Gene-pyramiding by combining two or more dissimilar Bacillus thuringiensis (Bt) proteins into a crop has been used to delay insect resistance. The durability of gene-pyramiding can be reduced by cross-resistance. Fall armyworm, Spodoptera frugiperda, is a major target pest of the Cry2Ab2 protein used in pyramided Bt corn and cotton. Here, we provide the first experimental evaluation of cross-resistance in S. frugiperda selected with Cry2Ab2 corn to multiple Bt sources including purified Bt proteins, Bt corn and Bt cotton. Concentration - response bioassays showed that resistance ratios for Cry2Ab2-resistant (RR) relative to Cry2Ab2-susceptible (SS) S. frugiperda were -1.4 for Cry1F, 1.2 for Cry1A.105, >26.7 for Cry2Ab2, >10.0 for Cry2Ae and -1.1 for Vip3A. Larvae of Cry2Ab2-heterozygous (RS), SS and RR S. frugiperda were all susceptible to Bt corn and Bt cotton containing Cry1 (Cry1F or Cry1A.105) and/or Vip3A proteins. Pyramided Bt cotton containing Cry1Ac + Cry2Ab2 or Cry1Ab + Cry2Ae were also effective against SS and RS, but not RR. These findings suggest that Cry2Ab2-corn-selected S. frugiperda is not cross-resistant to Cry1F, Cry1A.105 or Vip3A protein, or corn and cotton plants containing these Bt proteins, but it can cause strong cross-resistance to Cry2Ae and Bt crops expressing similar Bt proteins. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Toxicity and Binding Studies of Bacillus thuringiensis Cry1Ac, Cry1F, Cry1C, and Cry2A Proteins in the Soybean Pests Anticarsia gemmatalis and Chrysodeixis (Pseudoplusia) includens.

PubMed

Bel, Yolanda; Sheets, Joel J; Tan, Sek Yee; Narva, Kenneth E; Escriche, Baltasar

2017-06-01

Anticarsia gemmatalis (velvetbean caterpillar) and Chrysodeixis includens (soybean looper, formerly named Pseudoplusia includens ) are two important defoliating insects of soybeans. Both lepidopteran pests are controlled mainly with synthetic insecticides. Alternative control strategies, such as biopesticides based on the Bacillus thuringiensis (Bt) toxins or transgenic plants expressing Bt toxins, can be used and are increasingly being adopted. Studies on the insect susceptibilities and modes of action of the different Bt toxins are crucial to determine management strategies to control the pests and to delay outbreaks of insect resistance. In the present study, the susceptibilities of both soybean pests to the Bt toxins Cry1Ac, Cry1Fa, Cry1Ca, and Cry2Aa have been investigated. Bioassays performed in first-instar larvae showed that both insects are susceptible to all these toxins. Competition-binding studies carried out with Cry1Ac and Cry1Fa 125 -iodine labeled proteins demonstrated the presence of specific binding sites for both of them on the midgut brush border membrane vesicles (BBMVs) of both A. gemmatalis and C. includens Competition-binding experiments and specific-binding inhibition studies performed with selected sugars and lectins indicated that Cry1Ac and Cry1Fa share some, but not all, binding sites in the midguts of both insects. Also, the Cry1Ac- or Cry1Fa-binding sites were not shared with Cry1Ca or Cry2Aa in either soybean pest. This study contributes to the knowledge of Bt toxicity and midgut toxin binding sites in A. gemmatalis and C. includens and sheds light on the cross-resistance potential of Cry1Ac, Cry1Fa, Cry1Ca, and Cry2Aa Bt proteins as candidate proteins for Bt-pyramided crops. IMPORTANCE In the present study, the toxicity and the mode of action of the Bacillus thuringiensis (Bt) toxins Cry1Ac, Cry1Fa, Cry1Ca, and Cry2Aa in Anticarsia gemmatalis and Chrysodeixis includens (important defoliating pests of soybeans) have been investigated. These studies are crucial for determining management strategies for pest control. Bioassays showed that both insects were susceptible to the toxins. Competition-binding studies demonstrated the presence of Cry1Fa- and Cry1Ac-specific binding sites in the midguts of both pests. These results, together with the results from binding inhibition studies performed with sugars and lectins, indicated that Cry1Ac and Cry1Fa share some, but not all, binding sites, and that they were not shared with Cry1Ca or Cry2Aa in either soybean pest. This study contributes to the knowledge of Bt toxicity in A. gemmatalis and C. includens and sheds light on the cross-resistance potential of Cry1Ac, Cry1Fa, Cry1Ca, and Cry2Aa Bt proteins as candidate proteins for Bt-pyramided crops. Copyright © 2017 Bel et al.

Aural localization of silent objects by active human biosonar: neural representations of virtual echo-acoustic space.

PubMed

Wallmeier, Ludwig; Kish, Daniel; Wiegrebe, Lutz; Flanagin, Virginia L

2015-03-01

Some blind humans have developed the remarkable ability to detect and localize objects through the auditory analysis of self-generated tongue clicks. These echolocation experts show a corresponding increase in 'visual' cortex activity when listening to echo-acoustic sounds. Echolocation in real-life settings involves multiple reflections as well as active sound production, neither of which has been systematically addressed. We developed a virtualization technique that allows participants to actively perform such biosonar tasks in virtual echo-acoustic space during magnetic resonance imaging (MRI). Tongue clicks, emitted in the MRI scanner, are picked up by a microphone, convolved in real time with the binaural impulse responses of a virtual space, and presented via headphones as virtual echoes. In this manner, we investigated the brain activity during active echo-acoustic localization tasks. Our data show that, in blind echolocation experts, activations in the calcarine cortex are dramatically enhanced when a single reflector is introduced into otherwise anechoic virtual space. A pattern-classification analysis revealed that, in the blind, calcarine cortex activation patterns could discriminate left-side from right-side reflectors. This was found in both blind experts, but the effect was significant for only one of them. In sighted controls, 'visual' cortex activations were insignificant, but activation patterns in the planum temporale were sufficient to discriminate left-side from right-side reflectors. Our data suggest that blind and echolocation-trained, sighted subjects may recruit different neural substrates for the same active-echolocation task. © 2015 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Morphology of the Nasal Apparatus in Pygmy (Kogia Breviceps) and Dwarf (K. Sima) Sperm Whales.

PubMed

Thornton, Steven W; Mclellan, William A; Rommel, Sentiel A; Dillaman, Richard M; Nowacek, Douglas P; Koopman, Heather N; Pabst, D Ann

2015-07-01

Odontocete echolocation clicks are generated by pneumatically driven phonic lips within the nasal passage, and propagated through specialized structures within the forehead. This study investigated the highly derived echolocation structures of the pygmy (Kogia breviceps) and dwarf (K. sima) sperm whales through careful dissections (N = 18 K. breviceps, 6 K. sima) and histological examinations (N = 5 K. breviceps). This study is the first to show that the entire kogiid sound production and transmission pathway is acted upon by complex facial muscles (likely derivations of the m. maxillonasolabialis). Muscles appear capable of tensing and separating the solitary pair of phonic lips, which would control echolocation click frequencies. The phonic lips are enveloped by the "vocal cap," a morphologically complex, connective tissue structure unique to kogiids. Extensive facial muscles appear to control the position of this structure and its spatial relationship to the phonic lips. The vocal cap's numerous air crypts suggest that it may reflect sounds. Muscles encircling the connective tissue case that surrounds the spermaceti organ may change its shape and/or internal pressure. These actions may influence the acoustic energy transmitted from the phonic lips, through this lipid body, to the melon. Facial and rostral muscles act upon the length of the melon, suggesting that the sound "beam" can be focused as it travels through the melon and into the environment. This study suggests that the kogiid echolocation system is highly tunable. Future acoustic studies are required to test these hypotheses and gain further insight into the kogiid echolocation system. © 2015 Wiley Periodicals, Inc.

Classification of echolocation clicks from odontocetes in the Southern California Bight.

PubMed

Roch, Marie A; Klinck, Holger; Baumann-Pickering, Simone; Mellinger, David K; Qui, Simon; Soldevilla, Melissa S; Hildebrand, John A

2011-01-01

This study presents a system for classifying echolocation clicks of six species of odontocetes in the Southern California Bight: Visually confirmed bottlenose dolphins, short- and long-beaked common dolphins, Pacific white-sided dolphins, Risso's dolphins, and presumed Cuvier's beaked whales. Echolocation clicks are represented by cepstral feature vectors that are classified by Gaussian mixture models. A randomized cross-validation experiment is designed to provide conditions similar to those found in a field-deployed system. To prevent matched conditions from inappropriately lowering the error rate, echolocation clicks associated with a single sighting are never split across the training and test data. Sightings are randomly permuted before assignment to folds in the experiment. This allows different combinations of the training and test data to be used while keeping data from each sighting entirely in the training or test set. The system achieves a mean error rate of 22% across 100 randomized three-fold cross-validation experiments. Four of the six species had mean error rates lower than the overall mean, with the presumed Cuvier's beaked whale clicks showing the best performance (<2% error rate). Long-beaked common and bottlenose dolphins proved the most difficult to classify, with mean error rates of 53% and 68%, respectively.

Psychophysics of human echolocation.

PubMed

Schörnich, Sven; Wallmeier, Ludwig; Gessele, Nikodemus; Nagy, Andreas; Schranner, Michael; Kish, Daniel; Wiegrebe, Lutz

2013-01-01

The skills of some blind humans orienting in their environment through the auditory analysis of reflections from self-generated sounds have received only little scientific attention to date. Here we present data from a series of formal psychophysical experiments with sighted subjects trained to evaluate features of a virtual echo-acoustic space, allowing for rigid and fine-grain control of the stimulus parameters. The data show how subjects shape both their vocalisations and auditory analysis of the echoes to serve specific echo-acoustic tasks. First, we show that humans can echo-acoustically discriminate target distances with a resolution of less than 1 m for reference distances above 3.4 m. For a reference distance of 1.7 m, corresponding to an echo delay of only 10 ms, distance JNDs were typically around 0.5 m. Second, we explore the interplay between the precedence effect and echolocation. We show that the strong perceptual asymmetry between lead and lag is weakened during echolocation. Finally, we show that through the auditory analysis of self-generated sounds, subjects discriminate room-size changes as small as 10%.In summary, the current data confirm the practical efficacy of human echolocation, and they provide a rigid psychophysical basis for addressing its neural foundations.

Target distance-dependent variation of hearing sensitivity during echolocation in a false killer whale.

PubMed

Supin, Alexander Ya; Nachtigall, Paul E; Breese, Marlee

2010-06-01

Evidence of varying hearing sensitivity according to the target distance was obtained in a false killer whale Pseudorca crassidens during echolocation. Auditory evoked potentials (AEPs) triggered by echolocation clicks were recorded. The target distance varied from 1 to 6 m. The records contained AEPs to the self-heard emitted click and AEPs to the echoes. Mean level of echolocation clicks depended on distance (the longer the distance, the higher the click level), however, the effect of click level on AEP amplitude was eliminated by extracting AEPs to clicks of certain particular levels. The amplitude of the echo-provoked AEP was almost independent of distance, however, the amplitude of the AEP to the emitted click, did depend on distance within a range from 1 to 4 m: the longer the distance, the higher the amplitude. The latter result is interpreted as confirmational evidence that the animal is capable of varying hearing sensitivity according to target distance. The variation of hearing sensitivity may help to compensate for the echo attenuation with distance; as a secondary effect, this variation manifested itself in a variation of the amplitude of the AEP to emitted clicks.

Recording and quantification of ultrasonic echolocation clicks from free-ranging toothed whales

NASA Astrophysics Data System (ADS)

Madsen, P. T.; Wahlberg, M.

2007-08-01

Toothed whales produce short, ultrasonic clicks of high directionality and source level to probe their environment acoustically. This process, termed echolocation, is to a large part governed by the properties of the emitted clicks. Therefore derivation of click source parameters from free-ranging animals is of increasing importance to understand both how toothed whales use echolocation in the wild and how they may be monitored acoustically. This paper addresses how source parameters can be derived from free-ranging toothed whales in the wild using calibrated multi-hydrophone arrays and digital recorders. We outline the properties required of hydrophones, amplifiers and analog to digital converters, and discuss the problems of recording echolocation clicks on the axis of a directional sound beam. For accurate localization the hydrophone array apertures must be adapted and scaled to the behavior of, and the range to, the clicking animal, and precise information on hydrophone locations is critical. We provide examples of localization routines and outline sources of error that lead to uncertainties in localizing clicking animals in time and space. Furthermore we explore approaches to time series analysis of discrete versions of toothed whale clicks that are meaningful in a biosonar context.

Echolocation click rates and behavior of foraging Hawaiian spinner dolphins

NASA Astrophysics Data System (ADS)

Benoit-Bird, Kelly J.; Au, Whitlow W. L.

2004-05-01

Groups of spinner dolphins work together to actively aggregate small animals in the deep-scattering layer that serve as their prey. Detailed information on dolphin foraging behavior, obtained with a 200-kHz multibeam sonar (Simrad MS2000), made it possible to correlate echolocation and foraging. Fifty-six groups of spinner dolphins foraging at night within a midwater micronekton sound-scattering layer were observed with the sonar. During sonar surveys, the rates of whistles and echolocation clicks were measured using four hydrophones at 6-m depth intervals. Significant differences in click rates were found between depths and between the different stages of foraging. Groups of foraging dolphins ranged in size from 16 to 28 dolphins. Click rates were not significantly affected by the number of dolphins in a foraging group. Contrary to initial predictions, click rates were relatively low when sonar data indicated that pairs of dolphins were actively feeding. Highest echolocation rates occurred within the scattering layer, during transitions between foraging states. Whistles were only detected when dolphins were not in a foraging formation and when animals were surfacing. This suggests clicks may be used directly or indirectly to cue group movement during foraging.

Detection and classification of underwater targets by echolocating dolphins

NASA Astrophysics Data System (ADS)

Au, Whitlow

2003-10-01

Many experiments have been performed with echolocating dolphins to determine their target detection and discrimination capabilities. Target detection experiments have been performed in a naturally noisy environment, with masking noise and with both phantom echoes and masking noise, and in reverberation. The echo energy to rms noise spectral density for the Atlantic bottlenose dolphin (Tursiops truncatus) at the 75% correct response threshold is approximately 7.5 dB whereas for the beluga whale (Delphinapterus leucas) the threshold is approximately 1 dB. The dolphin's detection threshold in reverberation is approximately 2.5 dB vs 2 dB for the beluga. The difference in performance between species can probably be ascribed to differences in how both species perceived the task. The bottlenose dolphin may be performing a combination detection/discrimination task whereas the beluga may be performing a simple detection task. Echolocating dolphins also have the capability to make fine discriminate of target properties such as wall thickness difference of water-filled cylinders and material differences in metallic plates. The high resolution property of the animal's echolocation signals and the high dynamic range of its auditory system are important factors in their outstanding discrimination capabilities.

Multiple assays indicate varying levels of cross resistance of Cry3Bb1-selected field populations of the western corn rootworm to mCry3A, eCry3.1Ab, and Cry34/35Ab1

USDA-ARS?s Scientific Manuscript database

Minnesota populations of the western corn rootworm (WCR) surviving Cry3Bb1-expressing corn in the field and WCR populations assumed to be susceptible to all Bt proteins were evaluated for susceptibility to Cry3Bb1, mCry3A, eCry3.1Ab, and Cry34/35Ab1 in diet assays and three different plant-based ass...

Object representation in the bottlenose dolphin (Tursiops truncatus): integration of visual and echoic information.

PubMed

Harley, H E; Roitblat, H L; Nachtigall, P E

1996-04-01

A dolphin performed a 3-alternative matching-to-sample task in different modality conditions (visual/echoic, both vision and echolocation: visual, vision only; echoic, echolocation only). In Experiment 1, training occurred in the dual-modality (visual/echoic) condition. Choice accuracy in tests of all conditions was above chance without further training. In Experiment 2, unfamiliar objects with complementary similarity relations in vision and echolocation were presented in single-modality conditions until accuracy was about 70%. When tested in the visual/echoic condition, accuracy immediately rose (95%), suggesting integration across modalities. In Experiment 3, conditions varied between presentation of sample and alternatives. The dolphin successfully matched familiar objects in the cross-modal conditions. These data suggest that the dolphin has an object-based representational system.

Field Trial Performance of Herculex XTRA (Cry34Ab1/Cry35Ab1) and SmartStax (Cry34Ab1/Cry35Ab1 + Cry3Bb1) Hybrids and Soil Insecticides Against Western and Northern Corn Rootworms (Coleoptera: Chrysomelidae).

PubMed

Johnson, K D; Campbell, L A; Lepping, M D; Rule, D M

2017-06-01

Western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), and northern corn rootworm, Diabrotica barberi Smith and Lawrence (Coleoptera: Chrysomelidae), are important insect pests in corn, Zea mays L. For more than a decade, growers have been using transgenic plants expressing proteins from the bacterium Bacillus thuringiensis (Bt) to protect corn roots from feeding. In 2011, western corn rootworm populations were reported to have developed resistance to Bt hybrids expressing Cry3Bb1 and later found to be cross-resistant to hybrids expressing mCry3A and eCry3.1Ab. The identification of resistance to Cry3 (Cry3Bb1, mCry3A, and eCry3.1Ab) hybrids led to concerns about durability and efficacy of products with single traits and of products containing a pyramid of a Cry3 protein and the binary Bt proteins Cry34Ab1 and Cry35Ab1. From 2012 to 2014, 43 field trials were conducted across the central United States to estimate root protection provided by plants expressing Cry34Ab1/Cry35Ab1 alone (Herculex RW) or pyramided with Cry3Bb1 (SmartStax). These technologies were evaluated with and without soil-applied insecticides to determine if additional management measures provided benefit where Cry3 performance was reduced. Trials were categorized for analysis based on rootworm damage levels on Cry3-expressing hybrids and rootworm feeding pressure within each trial. Across scenarios, Cry34Ab1/Cry35Ab1 hybrids provided excellent root protection. Pyramided traits provided greater root and yield protection than non-Bt plus a soil-applied insecticide, and only in trials where larval feeding pressure exceeded two nodes of damage did Cry34Ab1/Cry35Ab1 single-trait hybrids and pyramided hybrids show greater root protection from the addition of soil-applied insecticides. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Evidence of Field-Evolved Resistance of Spodoptera frugiperda to Bt Corn Expressing Cry1F in Brazil That Is Still Sensitive to Modified Bt Toxins

PubMed Central

Monnerat, Rose; Martins, Erica; Macedo, Cristina; Queiroz, Paulo; Praça, Lilian; Soares, Carlos Marcelo; Moreira, Helio; Grisi, Isabella; Silva, Joseane; Soberon, Mario; Bravo, Alejandra

2015-01-01

Brazil ranked second only to the United States in hectares planted to genetically modified crops in 2013. Recently corn producers in the Cerrado region reported that the control of Spodoptera frugiperda with Bt corn expressing Cry1Fa has decreased, forcing them to use chemicals to reduce the damage caused by this insect pest. A colony of S. frugiperda was established from individuals collected in 2013 from Cry1Fa corn plants (SfBt) in Brazil and shown to have at least more than ten-fold higher resistance levels compared with a susceptible colony (Sflab). Laboratory assays on corn leaves showed that in contrast to SfLab population, the SfBt larvae were able to survive by feeding on Cry1Fa corn leaves. The SfBt population was maintained without selection for eight generations and shown to maintain high levels of resistance to Cry1Fa toxin. SfBt showed higher cross-resistance to Cry1Aa than to Cry1Ab or Cry1Ac toxins. As previously reported, Cry1A toxins competed the binding of Cry1Fa to brush border membrane vesicles (BBMV) from SfLab insects, explaining cross-resistance to Cry1A toxins. In contrast Cry2A toxins did not compete Cry1Fa binding to SfLab-BBMV and no cross-resistance to Cry2A was observed, although Cry2A toxins show low toxicity to S. frugiperda. Bioassays with Cry1AbMod and Cry1AcMod show that they are highly active against both the SfLab and the SfBt populations. The bioassay data reported here show that insects collected from Cry1Fa corn in the Cerrado region were resistant to Cry1Fa suggesting that resistance contributed to field failures of Cry1Fa corn to control S. frugiperda. PMID:25830928

Inheritance of Cry1F resistance, cross-resistance and frequency of resistant alleles in Spodoptera frugiperda (Lepidoptera: Noctuidae).

PubMed

Vélez, A M; Spencer, T A; Alves, A P; Moellenbeck, D; Meagher, R L; Chirakkal, H; Siegfried, B D

2013-12-01

Transgenic maize, Zea maize L., expressing the Cry1F protein from Bacillus thuringiensis has been registered for Spodoptera frugiperda (J. E. Smith) control since 2003. Unexpected damage to Cry1F maize was reported in 2006 in Puerto Rico and Cry1F resistance in S. frugiperda was documented. The inheritance of Cry1F resistance was characterized in a S. frugiperda resistant strain originating from Puerto Rico, which displayed >289-fold resistance to purified Cry1F. Concentration-response bioassays of reciprocal crosses of resistant and susceptible parental populations indicated that resistance is recessive and autosomal. Bioassays of the backcross of the F1 generation crossed with the resistant parental strain suggest that a single locus is responsible for resistance. In addition, cross-resistance to Cry1Aa, Cry1Ab, Cry1Ac, Cry1Ba, Cry2Aa and Vip3Aa was assessed in the Cry1F-resistant strain. There was no significant cross-resistance to Cry1Aa, Cry1Ba and Cry2Aa, although only limited effects were observed in the susceptible strain. Vip3Aa was highly effective against susceptible and resistant insects indicating no cross-resistance with Cry1F. In contrast, low levels of cross-resistance were observed for both Cry1Ab and Cry1Ac. Because the resistance is recessive and conferred by a single locus, an F1 screening assay was used to measure the frequency of Cry1F-resistant alleles from populations of Florida and Texas in 2010 and 2011. A total frequency of resistant alleles of 0.13 and 0.02 was found for Florida and Texas populations, respectively, indicating resistant alleles could be found in US populations, although there have been no reports of reduced efficacy of Cry1F-expressing plants.

Evidence of field-evolved resistance of Spodoptera frugiperda to Bt corn expressing Cry1F in Brazil that is still sensitive to modified Bt toxins.

PubMed

Monnerat, Rose; Martins, Erica; Macedo, Cristina; Queiroz, Paulo; Praça, Lilian; Soares, Carlos Marcelo; Moreira, Helio; Grisi, Isabella; Silva, Joseane; Soberon, Mario; Bravo, Alejandra

2015-01-01

Brazil ranked second only to the United States in hectares planted to genetically modified crops in 2013. Recently corn producers in the Cerrado region reported that the control of Spodoptera frugiperda with Bt corn expressing Cry1Fa has decreased, forcing them to use chemicals to reduce the damage caused by this insect pest. A colony of S. frugiperda was established from individuals collected in 2013 from Cry1Fa corn plants (SfBt) in Brazil and shown to have at least more than ten-fold higher resistance levels compared with a susceptible colony (Sflab). Laboratory assays on corn leaves showed that in contrast to SfLab population, the SfBt larvae were able to survive by feeding on Cry1Fa corn leaves. The SfBt population was maintained without selection for eight generations and shown to maintain high levels of resistance to Cry1Fa toxin. SfBt showed higher cross-resistance to Cry1Aa than to Cry1Ab or Cry1Ac toxins. As previously reported, Cry1A toxins competed the binding of Cry1Fa to brush border membrane vesicles (BBMV) from SfLab insects, explaining cross-resistance to Cry1A toxins. In contrast Cry2A toxins did not compete Cry1Fa binding to SfLab-BBMV and no cross-resistance to Cry2A was observed, although Cry2A toxins show low toxicity to S. frugiperda. Bioassays with Cry1AbMod and Cry1AcMod show that they are highly active against both the SfLab and the SfBt populations. The bioassay data reported here show that insects collected from Cry1Fa corn in the Cerrado region were resistant to Cry1Fa suggesting that resistance contributed to field failures of Cry1Fa corn to control S. frugiperda.

Crying in Middle Childhood: A Report on Gender Differences.

PubMed

Jellesma, Francine C; Vingerhoets, Ad J J M

2012-10-01

The aims of this study were (1) to confirm gender differences in crying in middle childhood and (2) to identify factors that may explain why girls cry more than boys in a Dutch sample (North Holland and Utrecht). We examined 186 children's (age: 9-13 years) self-reports on crying, catharsis, seeking support for feelings, and internalizing feelings. Girls reported a greater crying frequency and crying proneness, and more emotional and physical catharsis after crying. In addition, they more frequently sought support for feelings and more often experienced sadness and somatic complaints than boys. Seeking help for negative feelings and the experience of sadness and somatic complaints were positively associated with crying frequency and crying proneness. Emotional catharsis was positively linked to crying proneness. Support was found for the potential mediating role of sadness and somatic complaints with respect to the gender difference in crying frequency and for the potential mediating role of emotional catharsis and somatic complaints for crying proneness. This study demonstrates that gender differences in crying frequency already exist in middle childhood and the findings suggest a linkage between these gender differences in crying and psychosocial factors.

Specific PCR primers directed to identify cryI and cryIII genes within a Bacillus thuringiensis strain collection.

PubMed Central

Cerón, J; Ortíz, A; Quintero, R; Güereca, L; Bravo, A

1995-01-01

In this paper we describe a PCR strategy that can be used to rapidly identify Bacillus thuringiensis strains that harbor any of the known cryI or cryIII genes. Four general PCR primers which amplify DNA fragments from the known cryI or cryIII genes were selected from conserved regions. Once a strain was identified as an organism that contains a particular type of cry gene, it could be easily characterized by performing additional PCR with specific cryI and cryIII primers selected from variable regions. The method described in this paper can be used to identify the 10 different cryI genes and the five different cryIII genes. One feature of this screening method is that each cry gene is expected to produce a PCR product having a precise molecular weight. The genes which produce PCR products having different sizes probably represent strains that harbor a potentially novel cry gene. Finally, we present evidence that novel crystal genes can be identified by the method described in this paper. PMID:8526493