1
|
Jansen W, Steckel J. SonoNERFs: Neural Radiance Fields Applied to Biological Echolocation Systems Allow 3D Scene Reconstruction through Perceptual Prediction. Biomimetics (Basel) 2024; 9:321. [PMID: 38921202 PMCID: PMC11201853 DOI: 10.3390/biomimetics9060321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2024] [Revised: 05/24/2024] [Accepted: 05/25/2024] [Indexed: 06/27/2024] Open
Abstract
In this paper, we introduce SonoNERFs, a novel approach that adapts Neural Radiance Fields (NeRFs) to model and understand the echolocation process in bats, focusing on the challenges posed by acoustic data interpretation without phase information. Leveraging insights from the field of optical NeRFs, our model, termed SonoNERF, represents the acoustic environment through Neural Reflectivity Fields. This model allows us to reconstruct three-dimensional scenes from echolocation data, obtained by simulating how bats perceive their surroundings through sound. By integrating concepts from biological echolocation and modern computational models, we demonstrate the SonoNERF's ability to predict echo spectrograms for unseen echolocation poses and effectively reconstruct a mesh-based and energy-based representation of complex scenes. Our work bridges a gap in understanding biological echolocation and proposes a methodological framework that provides a first-order model of how scene understanding might arise in echolocating animals. We demonstrate the efficacy of the SonoNERF model on three scenes of increasing complexity, including some biologically relevant prey-predator interactions.
Collapse
Affiliation(s)
- Wouter Jansen
- Cosys-Lab, Faculty of Applied Engineering, University of Antwerp, 2020 Antwerpen, Belgium;
- Flanders Make Strategic Research Centre, 3920 Lommel, Belgium
| | - Jan Steckel
- Cosys-Lab, Faculty of Applied Engineering, University of Antwerp, 2020 Antwerpen, Belgium;
- Flanders Make Strategic Research Centre, 3920 Lommel, Belgium
| |
Collapse
|
2
|
Amichai E, Boerma DB, Page RA, Swartz SM, ter Hofstede HM. By a whisker: the sensory role of vibrissae in hovering flight in nectarivorous bats. Proc Biol Sci 2023; 290:20222085. [PMID: 36722088 PMCID: PMC9890094 DOI: 10.1098/rspb.2022.2085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Accepted: 12/23/2022] [Indexed: 02/02/2023] Open
Abstract
Whiskers are important tactile structures widely used across mammals for a variety of sensory functions, but it is not known how bats-representing about a fifth of all extant mammal species-use them. Nectar-eating bats typically have long vibrissae (long, stiff hairs) arranged in a forward-facing brush-like formation that is not present in most non-nectarivorous bats. They also commonly use a unique flight strategy to access their food-hovering flight. Here we investigated whether these species use their vibrissae to optimize their feeding by assisting fine flight control. We used behavioural experiments to test if bats' flight trajectory into the flower changed after vibrissa removal, and phylogenetic comparative methods to test whether vibrissa length is related to nectarivory. We found that bat flight trajectory was altered after vibrissae removal and that nectarivorous bats possess longer vibrissae than non-nectivorous species, providing evidence of an additional source of information in bats' diverse sensory toolkit.
Collapse
Affiliation(s)
- Eran Amichai
- Ecology, Evolution, Environment & Society Graduate Program, Dartmouth College, Hanover, NH 03755, USA
- Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA
| | - David B. Boerma
- Department of Mammalogy, Division of Vertebrate Zoology, American Museum of Natural History, New York, NY 10024, USA
| | - Rachel A. Page
- Smithsonian Tropical Research Institute, Balboa, Ancón, Apartado 0843-03092, Republic of Panama
| | - Sharon M. Swartz
- Department of Ecology, Evolution, and Organismal Biology, Brown University, Providence, RI 012912, USA
- School of Engineering, Brown University, Providence, RI 012912, USA
| | - Hannah M. ter Hofstede
- Ecology, Evolution, Environment & Society Graduate Program, Dartmouth College, Hanover, NH 03755, USA
- Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA
- Smithsonian Tropical Research Institute, Balboa, Ancón, Apartado 0843-03092, Republic of Panama
| |
Collapse
|
3
|
Zhu H, Gupta AK, Wu X, Goldsworthy M, Wang R, Mikkilineni M, Müller R. A validation study for a bat-inspired sonar sensing simulator. PLoS One 2023; 18:e0280631. [PMID: 36662796 PMCID: PMC9858711 DOI: 10.1371/journal.pone.0280631] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Accepted: 01/04/2023] [Indexed: 01/21/2023] Open
Abstract
Many species of bats rely on echoes to forage and navigate in densely vegetated environments. Foliage echoes in some cases can help bats gather information about the environment, whereas in others may generate clutter that can mask prey echoes during foraging. It is therefore important to study foliage echoes and their role in bat's sensory ecology. In our prior work, a foliage echo simulator has been developed; simulated echoes has been compared with field recordings using a biomimetic sonar head. In this work, we improve the existing simulator by allowing more flexible experimental setups and enabling a closer match with the experiments. Specifically, we add additional features into the simulator including separate directivity patterns for emitter and receiver, the ability to place emitter and receiver at distinct locations, and multiple options to orient the foliage to mimic natural conditions like strong wind. To study how accurately the simulator can replicate the real echo-generating process, we compare simulated echoes with experimental echoes measured by ensonifying a single leaf across four different species of trees. We further extend the prior work on estimating foliage parameters to estimating a map of the environment.
Collapse
Affiliation(s)
- Hongxiao Zhu
- Department of Statistics, Virginia Tech, Blacksburg, Virginia, United States of America
| | - Anupam Kumar Gupta
- Department of Engineering Maths and Bristol Robotics Laboratory, University of Bristol, Bristol, United Kingdom
| | - Xiaowei Wu
- Department of Statistics, Virginia Tech, Blacksburg, Virginia, United States of America
| | - Michael Goldsworthy
- Department of Computer Science, Virginia Tech, Blacksburg, Virginia, United States of America
| | - Ruihao Wang
- Department of Mechanical Engineering, Virginia Tech, Blacksburg, Virginia, United States of America
| | - Mohitha Mikkilineni
- Department of Electrical and Computer Engineering, Virginia Tech, Blacksburg, Virginia, United States of America
| | - Rolf Müller
- Department of Mechanical Engineering, Virginia Tech, Blacksburg, Virginia, United States of America
| |
Collapse
|
4
|
Smotherman MS, Croft T, Macias S. Biosonar discrimination of fine surface textures by echolocating free-tailed bats. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.969350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Echolocating bats are able to discriminate between different surface textures based on the spectral properties of returning echoes. This capability is likely to be important for recognizing prey and for finding suitably perching sites along smooth cave walls. Previous studies showed that bats may exploit echo spectral interference patterns in returning echoes to classify surface textures, but a systematic assessment of the limits of their discrimination performance is lacking and may provide important clues about the neural mechanisms by which bats reconstruct target features based on echo acoustic cues. We trained three Mexican free-tailed bats (Tadarida brasiliensis) on a Y-maze to discriminate between the surfaces of 10 different sheets of aluminum-oxide abrasive sandpapers differing in standardized grit sizes ranging from 40 grit (coarse, 425 μm mean particle diameter) to 240 grit (fine, 54 μm mean particle diameter). Bats were rewarded for choosing the coarsest of two choices. All three bats easily discriminated all abrasive surfaces from a smooth plexiglass control and between all sandpaper comparisons except the two with the smallest absolute difference in mean particle sizes, the 150 vs. 180 grit (92 vs. 82 μm) and the 220 vs. 240 grit (68 vs. 54 μm) surfaces. These results indicate that echolocating free-tailed bats can use slight variations in the echo spectral envelope to remotely classify very fine surface textures with an acuity of at least 23 μm, which rivals direct tactile discrimination performance of the human hand.
Collapse
|
5
|
Pulver CA, Celiker E, Woodrow C, Geipel I, Soulsbury CD, Cullen DA, Rogers SM, Veitch D, Montealegre-Z F. Ear pinnae in a neotropical katydid (Orthoptera: Tettigoniidae) function as ultrasound guides for bat detection. eLife 2022; 11:77628. [PMID: 36170144 PMCID: PMC9519150 DOI: 10.7554/elife.77628] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2022] [Accepted: 09/02/2022] [Indexed: 11/29/2022] Open
Abstract
Early predator detection is a key component of the predator-prey arms race and has driven the evolution of multiple animal hearing systems. Katydids (Insecta) have sophisticated ears, each consisting of paired tympana on each foreleg that receive sound both externally, through the air, and internally via a narrowing ear canal running through the leg from an acoustic spiracle on the thorax. These ears are pressure-time difference receivers capable of sensitive and accurate directional hearing across a wide frequency range. Many katydid species have cuticular pinnae which form cavities around the outer tympanal surfaces, but their function is unknown. We investigated pinnal function in the katydid Copiphora gorgonensis by combining experimental biophysics and numerical modelling using 3D ear geometries. We found that the pinnae in C. gorgonensis do not assist in directional hearing for conspecific call frequencies, but instead act as ultrasound detectors. Pinnae induced large sound pressure gains (20–30 dB) that enhanced sound detection at high ultrasonic frequencies (>60 kHz), matching the echolocation range of co-occurring insectivorous gleaning bats. These findings were supported by behavioural and neural audiograms and pinnal cavity resonances from live specimens, and comparisons with the pinnal mechanics of sympatric katydid species, which together suggest that katydid pinnae primarily evolved for the enhanced detection of predatory bats.
Collapse
Affiliation(s)
- Christian A Pulver
- University of Lincoln, School of Life & Environmental Sciences, Joseph Banks Laboratories, Green Lane, Lincoln, United Kingdom
| | - Emine Celiker
- University of Lincoln, School of Life & Environmental Sciences, Joseph Banks Laboratories, Green Lane, Lincoln, United Kingdom
| | - Charlie Woodrow
- University of Lincoln, School of Life & Environmental Sciences, Joseph Banks Laboratories, Green Lane, Lincoln, United Kingdom
| | - Inga Geipel
- Smithsonian Tropical Research Institute, Balboa, Panama.,CoSys Lab, Faculty of Applied Engineering, University of Antwerp, Antwerp, Belgium.,Flanders Make Strategic Research Centre, Lommel, Belgium
| | - Carl D Soulsbury
- University of Lincoln, School of Life & Environmental Sciences, Joseph Banks Laboratories, Green Lane, Lincoln, United Kingdom
| | - Darron A Cullen
- University of Lincoln, School of Life & Environmental Sciences, Joseph Banks Laboratories, Green Lane, Lincoln, United Kingdom
| | - Stephen M Rogers
- University of Lincoln, School of Life & Environmental Sciences, Joseph Banks Laboratories, Green Lane, Lincoln, United Kingdom
| | - Daniel Veitch
- University of Lincoln, School of Life & Environmental Sciences, Joseph Banks Laboratories, Green Lane, Lincoln, United Kingdom
| | - Fernando Montealegre-Z
- University of Lincoln, School of Life & Environmental Sciences, Joseph Banks Laboratories, Green Lane, Lincoln, United Kingdom
| |
Collapse
|
6
|
Weissflog A, Markesteijn L, Aiello A, Healey J, Geipel I. Do prey shape, time of day, and plant trichomes affect the predation rate on plasticine prey in tropical rainforests? Biotropica 2022. [DOI: 10.1111/btp.13150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Anita Weissflog
- School of Natural Sciences Bangor University Bangor, Gwynedd UK
- Smithsonian Tropical Research Institute Balboa Panama
| | - Lars Markesteijn
- School of Natural Sciences Bangor University Bangor, Gwynedd UK
- Smithsonian Tropical Research Institute Balboa Panama
- Area of Biodiversity and Conservation, Department of Biology and Geography, Physics and Inorganic Chemistry University Rey Juan Carlos Madrid Spain
| | | | - John Healey
- School of Natural Sciences Bangor University Bangor, Gwynedd UK
| | - Inga Geipel
- Smithsonian Tropical Research Institute Balboa Panama
- CoSys Lab, Faculty of Applied Engineering University of Antwerp Antwerpen Belgium
- Flanders Make Strategic Research Centre Lommel Belgium
| |
Collapse
|
7
|
Verreycken E, Simon R, Quirk-Royal B, Daems W, Barber J, Steckel J. Bio-acoustic tracking and localization using heterogeneous, scalable microphone arrays. Commun Biol 2021; 4:1275. [PMID: 34759372 PMCID: PMC8581004 DOI: 10.1038/s42003-021-02746-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Accepted: 10/04/2021] [Indexed: 11/09/2022] Open
Abstract
Microphone arrays are an essential tool in the field of bioacoustics as they provide a non-intrusive way to study animal vocalizations and monitor their movement and behavior. Microphone arrays can be used for passive localization and tracking of sound sources while analyzing beamforming or spatial filtering of the emitted sound. Studying free roaming animals usually requires setting up equipment over large areas and attaching a tracking device to the animal which may alter their behavior. However, monitoring vocalizing animals through arrays of microphones, spatially distributed over their habitat has the advantage that unrestricted/unmanipulated animals can be observed. Important insights have been achieved through the use of microphone arrays, such as the convergent acoustic field of view in echolocating bats or context-dependent functions of avian duets. Here we show the development and application of large flexible microphone arrays that can be used to localize and track any vocalizing animal and study their bio-acoustic behavior. In a first experiment with hunting pallid bats the acoustic data acquired from a dense array with 64 microphones revealed details of the bats' echolocation beam in previously unseen resolution. We also demonstrate the flexibility of the proposed microphone array system in a second experiment, where we used a different array architecture allowing to simultaneously localize several species of vocalizing songbirds in a radius of 75 m. Our technology makes it possible to do longer measurement campaigns over larger areas studying changing habitats and providing new insights for habitat conservation. The flexible nature of the technology also makes it possible to create dense microphone arrays that can enhance our understanding in various fields of bioacoustics and can help to tackle the analytics of complex behaviors of vocalizing animals.
Collapse
Affiliation(s)
- Erik Verreycken
- CoSys-Lab, University of Antwerp, Antwerp, Belgium.
- Flanders Make, Strategic Research Centre, Lommel, Belgium.
| | - Ralph Simon
- CoSys-Lab, University of Antwerp, Antwerp, Belgium
- Flanders Make, Strategic Research Centre, Lommel, Belgium
- Nuremberg Zoo, Am Tiergarten 30, 90480, Nürnberg, Germany
| | - Brandt Quirk-Royal
- Department of Biological Sciences, Boise State University, Boise, ID, USA
| | - Walter Daems
- CoSys-Lab, University of Antwerp, Antwerp, Belgium
- Flanders Make, Strategic Research Centre, Lommel, Belgium
| | - Jesse Barber
- Department of Biological Sciences, Boise State University, Boise, ID, USA
| | - Jan Steckel
- CoSys-Lab, University of Antwerp, Antwerp, Belgium
- Flanders Make, Strategic Research Centre, Lommel, Belgium
| |
Collapse
|
8
|
Muñoz MI, Halfwerk W. Amplification of frog calls by reflective leaf substrates: implications for terrestrial and arboreal species. BIOACOUSTICS 2021. [DOI: 10.1080/09524622.2021.1978319] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Matías I. Muñoz
- Department of Ecological Science, VU University, Amsterdam, The Netherlands
| | - Wouter Halfwerk
- Department of Ecological Science, VU University, Amsterdam, The Netherlands
| |
Collapse
|
9
|
Hearing sensitivity: An underlying mechanism for niche differentiation in gleaning bats. Proc Natl Acad Sci U S A 2021; 118:2024943118. [PMID: 34426521 DOI: 10.1073/pnas.2024943118] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Tropical ecosystems are known for high species diversity. Adaptations permitting niche differentiation enable species to coexist. Historically, research focused primarily on morphological and behavioral adaptations for foraging, roosting, and other basic ecological factors. Another important factor, however, is differences in sensory capabilities. So far, studies mainly have focused on the output of behavioral strategies of predators and their prey preference. Understanding the coexistence of different foraging strategies, however, requires understanding underlying cognitive and neural mechanisms. In this study, we investigate hearing in bats and how it shapes bat species coexistence. We present the hearing thresholds and echolocation calls of 12 different gleaning bats from the ecologically diverse Phyllostomid family. We measured their auditory brainstem responses to assess their hearing sensitivity. The audiograms of these species had similar overall shapes but differed substantially for frequencies below 9 kHz and in the frequency range of their echolocation calls. Our results suggest that differences among bats in hearing abilities contribute to the diversity in foraging strategies of gleaning bats. We argue that differences in auditory sensitivity could be important mechanisms shaping diversity in sensory niches and coexistence of species.
Collapse
|
10
|
Malinka CE, Rojano-Doñate L, Madsen PT. Directional biosonar beams allow echolocating harbour porpoises to actively discriminate and intercept closely spaced targets. J Exp Biol 2021; 224:271830. [PMID: 34387665 DOI: 10.1242/jeb.242779] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 06/28/2021] [Indexed: 10/20/2022]
Abstract
Echolocating toothed whales face the problem that high sound speeds in water mean that echoes from closely spaced targets will arrive at time delays within their reported auditory integration time of some 264 µs. Here, we test the hypothesis that echolocating harbour porpoises cannot resolve and discriminate targets within a clutter interference zone given by their integration time. To do this, we trained two harbour porpoises (Phocoena phocoena) to actively approach and choose between two spherical targets at four varying inter-target distances (13.5, 27, 56 and 108 cm) in a two-alternative forced-choice task. The free-swimming, blindfolded porpoises were tagged with a sound and movement tag (DTAG4) to record their echoic scene and acoustic outputs. The known ranges between targets and the porpoise, combined with the sound levels received on target-mounted hydrophones revealed how the porpoises controlled their acoustic gaze. When targets were close together, the discrimination task was more difficult because of smaller echo time delays and lower echo level ratios between the targets. Under these conditions, buzzes were longer and started from farther away, source levels were reduced at short ranges, and the porpoises clicked faster, scanned across the targets more, and delayed making their discrimination decision until closer to the target. We conclude that harbour porpoises can resolve and discriminate closely spaced targets, suggesting a clutter rejection zone much shorter than their auditory integration time, and that such clutter rejection is greatly aided by spatial filtering with their directional biosonar beam.
Collapse
Affiliation(s)
- Chloe E Malinka
- Zoophysiology, Department of Biology, Aarhus University, Aarhus 8000, Denmark
| | - Laia Rojano-Doñate
- Zoophysiology, Department of Biology, Aarhus University, Aarhus 8000, Denmark
| | - Peter T Madsen
- Zoophysiology, Department of Biology, Aarhus University, Aarhus 8000, Denmark
| |
Collapse
|
11
|
Prakash H, Greif S, Yovel Y, Balakrishnan R. Acoustically eavesdropping bat predators take longer to capture katydid prey signalling in aggregation. J Exp Biol 2021; 224:268371. [PMID: 34047777 DOI: 10.1242/jeb.233262] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 04/21/2021] [Indexed: 11/20/2022]
Abstract
Prey that are signalling in aggregation become more conspicuous with increasing numbers and tend to attract more predators. Such grouping may, however, benefit prey by lowering the risk of being captured because of the predator's difficulty in targeting individuals. Previous studies have investigated anti-predatory benefits of prey aggregation using visual predators, but it is unclear whether such benefits are gained in an auditory context. We investigated whether katydids of the genus Mecopoda gain protection from their acoustically eavesdropping bat predator Megaderma spasma when calling in aggregation. In a choice experiment, bats approached calls of prey aggregations more often than those of prey calling alone, indicating that prey calling in aggregation are at higher risk. In prey capture tasks, however, the average time taken and the number of flight passes made by bats before capturing a katydid were significantly higher for prey calling in aggregation than when calling alone, indicating that prey face lower predation risk when calling in aggregation. Another common anti-predatory strategy, calling from within vegetation, increased the time taken by bats to capture katydids calling alone but did not increase the time taken to capture prey calling from aggregations. The increased time taken to capture prey calling in aggregation compared with solitary calling prey offers an escape opportunity, thus providing prey that signal acoustically in aggregations with anti-predatory benefits. For bats, greater detectability of calling prey aggregations is offset by lower foraging efficiency, and this trade-off may shape predator foraging strategies in natural environments.
Collapse
Affiliation(s)
- Harish Prakash
- Centre for Ecological Sciences, Indian Institute of Science, Bangalore 560012, India
| | - Stefan Greif
- School of Zoology, Faculty of Life Sciences, Tel-Aviv University, Tel Aviv 69978, Israel.,Sagol School of Neuroscience, Tel-Aviv University, Tel Aviv 69978, Israel
| | - Yossi Yovel
- School of Zoology, Faculty of Life Sciences, Tel-Aviv University, Tel Aviv 69978, Israel.,Sagol School of Neuroscience, Tel-Aviv University, Tel Aviv 69978, Israel
| | - Rohini Balakrishnan
- Centre for Ecological Sciences, Indian Institute of Science, Bangalore 560012, India
| |
Collapse
|
12
|
Previšić A, Vilenica M, Vučković N, Petrović M, Rožman M. Aquatic Insects Transfer Pharmaceuticals and Endocrine Disruptors from Aquatic to Terrestrial Ecosystems. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:3736-3746. [PMID: 33650859 PMCID: PMC8031366 DOI: 10.1021/acs.est.0c07609] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
A wide range of pharmaceuticals and endocrine disrupting compounds enter freshwaters globally. As these contaminants are transported through aquatic food webs, understanding their impacts on both aquatic and terrestrial ecosystems remains a major challenge. Here, we provide the first direct evidence of the transfer of pharmaceuticals and endocrine disruptors through the aquatic-terrestrial habitat linkage by emerging aquatic insects. We also show that the type of insect metamorphosis and feeding behavior determine the bioaccumulation patterns of these contaminants. Adult Trichoptera, an important food source for riparian predators, showed an increased body burden of pharmaceuticals and endocrine disruptors. This implies that terrestrial predators, such as spiders, birds, and bats, are exposed to mixtures of pharmaceuticals and endocrine disruptors of aquatic origin, which may impact their physiology and population dynamics. Overall, our study provides valuable insights into the bioaccumulation patterns and trophic cross-ecosystem transfer of these contaminants, from aquatic primary producers to terrestrial predators.
Collapse
Affiliation(s)
- Ana Previšić
- Department
of Biology, Zoology, Faculty of Science, University of Zagreb, Rooseveltov Trg 6, 10000 Zagreb, Croatia
| | - Marina Vilenica
- Faculty
of Teacher Education, University of Zagreb, Trg Matice hrvatske 12, 44250 Petrinja, Croatia
| | - Natalija Vučković
- Department
of Biology, Zoology, Faculty of Science, University of Zagreb, Rooseveltov Trg 6, 10000 Zagreb, Croatia
| | - Mira Petrović
- Catalan
Institute for Water Research, Carrer Emili Grahit 101, 17003 Girona, Spain
- Catalan
Institution for Research and Advanced Studies (ICREA), Barcelona, Spain
| | - Marko Rožman
- Ruđer
Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia
| |
Collapse
|
13
|
Lewanzik D, Goerlitz HR. Task-dependent vocal adjustments to optimize biosonar-based information acquisition. J Exp Biol 2021; 224:jeb234815. [PMID: 33234681 DOI: 10.1242/jeb.234815] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 11/13/2020] [Indexed: 01/09/2023]
Abstract
Animals need to acquire adequate and sufficient information to guide movements, yet information acquisition and processing are costly. Animals thus face a trade-off between gathering too little and too much information and, accordingly, actively adapt sensory input through motor control. Echolocating animals provide a unique opportunity to study the dynamics of adaptive sensing in naturally behaving animals, as every change in the outgoing echolocation signal directly affects information acquisition and the perception of the dynamic acoustic scene. Here, we investigated the flexibility with which bats dynamically adapt information acquisition depending on a task. We recorded the echolocation signals of wild-caught Western barbastelle bats (Barbastella barbastellus) while they were flying through an opening, drinking on the wing, landing on a wall and capturing prey. We show that the echolocation signal sequences during target approach differed in a task-dependent manner; bats started the target approach earlier and increased the information update rate more when the task became increasingly difficult, and bats also adjusted the dynamics of call duration shortening and peak frequency shifts accordingly. These task-specific differences existed from the onset of object approach, implying that bats plan their sensory-motor programme for object approach exclusively based on information received from search call echoes. We provide insight into how echolocating animals deal with the constraints they face when sequentially sampling the world through sound by adjusting acoustic information flow from slow to extremely fast in a highly dynamic manner. Our results further highlight the paramount importance of high behavioural flexibility for acquiring information.
Collapse
Affiliation(s)
- Daniel Lewanzik
- Acoustic and Functional Ecology, Max Planck Institute for Ornithology, Eberhard-Gwinner-Straße, 82319 Seewiesen, Germany
| | - Holger R Goerlitz
- Acoustic and Functional Ecology, Max Planck Institute for Ornithology, Eberhard-Gwinner-Straße, 82319 Seewiesen, Germany
| |
Collapse
|
14
|
Wagenhäuser PA, Wiegrebe L, Baier AL. Biosonar spatial resolution along the distance axis: revisiting the clutter interference zone. J Exp Biol 2020; 223:jeb224311. [PMID: 32843361 DOI: 10.1242/jeb.224311] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Accepted: 08/18/2020] [Indexed: 11/20/2022]
Abstract
Many echolocating bats forage close to vegetation - a chaotic arrangement of prey and foliage where multiple targets are positioned behind one another. Bats excel at determining distance: they measure the delay between the outgoing call and the returning echo. In their auditory cortex, delay-sensitive neurons form a topographic map, suggesting that bats can resolve echoes of multiple targets along the distance axis - a skill crucial for the forage-amongst-foliage scenario. We tested this hypothesis combining an auditory virtual reality with formal psychophysics: we simulated a prey item embedded in two foliage elements, one in front of and one behind the prey. The simulated spacing between 'prey' (target) and 'foliage' (maskers) was defined by the inter-masker delay (IMD). We trained Phyllostomus discolor bats to detect the target in the presence of the maskers, systematically varying both loudness and spacing of the maskers. We show that target detection is impaired when maskers are closely spaced (IMD<1 ms), but remarkably improves when the spacing is increased: the release from masking is approximately 5 dB for intermediate IMDs (1-3 ms) and increases to over 15 dB for large IMDs (≥9 ms). These results are comparable to those from earlier work on the clutter interference zone of bats (Simmons et al., 1988). They suggest that prey would enjoy considerable acoustic protection from closely spaced foliage, but also that the range resolution of bats would let them 'peek into gaps'. Our study puts target ranging into a meaningful context and highlights the limitations of computational topographic maps.
Collapse
Affiliation(s)
- Peter A Wagenhäuser
- Department of Biology II, Ludwig Maximilians University Munich, Großhaderner Str. 2, 82152 Planegg-Martinsried, Germany
| | - Lutz Wiegrebe
- Department of Biology II, Ludwig Maximilians University Munich, Großhaderner Str. 2, 82152 Planegg-Martinsried, Germany
| | - A Leonie Baier
- Department of Biology II, Ludwig Maximilians University Munich, Großhaderner Str. 2, 82152 Planegg-Martinsried, Germany
- Chair of Zoology, Technical University Munich, Liesel-Beckmann-Str. 4, 85354 Freising-Weihenstephan, Germany
| |
Collapse
|
15
|
Galloway JAM, Green SD, Stevens M, Kelley LA. Finding a signal hidden among noise: how can predators overcome camouflage strategies? Philos Trans R Soc Lond B Biol Sci 2020; 375:20190478. [PMID: 32420842 PMCID: PMC7331011 DOI: 10.1098/rstb.2019.0478] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Substantial progress has been made in the past 15 years regarding how prey use a variety of visual camouflage types to exploit both predator visual processing and cognition, including background matching, disruptive coloration, countershading and masquerade. By contrast, much less attention has been paid to how predators might overcome these defences. Such strategies include the evolution of more acute senses, the co-opting of other senses not targeted by camouflage, changes in cognition such as forming search images, and using behaviours that change the relationship between the cryptic individual and the environment or disturb prey and cause movement. Here, we evaluate the methods through which visual camouflage prevents detection and recognition, and discuss if and how predators might evolve, develop or learn counter-adaptations to overcome these. This article is part of the theme issue ‘Signal detection theory in recognition systems: from evolving models to experimental tests'.
Collapse
Affiliation(s)
- James A M Galloway
- Centre for Ecology and Conservation, University of Exeter (Penryn Campus), Cornwall TR10 9FE, UK
| | - Samuel D Green
- Centre for Ecology and Conservation, University of Exeter (Penryn Campus), Cornwall TR10 9FE, UK
| | - Martin Stevens
- Centre for Ecology and Conservation, University of Exeter (Penryn Campus), Cornwall TR10 9FE, UK
| | - Laura A Kelley
- Centre for Ecology and Conservation, University of Exeter (Penryn Campus), Cornwall TR10 9FE, UK
| |
Collapse
|
16
|
Geipel I, Kernan CE, Litterer AS, Carter GG, Page RA, Ter Hofstede HM. Predation risks of signalling and searching: bats prefer moving katydids. Biol Lett 2020; 16:20190837. [PMID: 32315594 DOI: 10.1098/rsbl.2019.0837] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Males signalling their attractiveness to females are at risk from predators that exploit mating signals to detect and locate prey. Signalling, however, is not the only risky activity in sexual interactions: mate searching can incur risk as well. Male Neotropical pseudophylline katydids produce both acoustic and vibrational signals (tremulations). Females reply to male signals with tremulations of their own, and both sexes walk to find one another. We asked if movement increases predation risk, and whether tremulation or walking was more attractive to predators. We offered the Neotropical gleaning bat Micronycteris microtis a series of two-choice tests, presenting the bats with katydid models that were motionless or moved in a way to mimic either tremulating or walking. We found that prey movements do put prey at risk. Although M. microtis can detect motionless prey on leaves, they preferred moving prey. Our study shows that movement can put searching or signalling prey in danger, potentially explaining why silent female katydids are frequently consumed by gleaning bats.
Collapse
Affiliation(s)
- Inga Geipel
- Smithsonian Tropical Research Institute, Apartado 0843-03092, Balboa, Panama
| | - Ciara E Kernan
- Smithsonian Tropical Research Institute, Apartado 0843-03092, Balboa, Panama.,Department of Biological Sciences, Dartmouth College, 78 College Street, Hanover, NH 03755, USA
| | - Amber S Litterer
- Smithsonian Tropical Research Institute, Apartado 0843-03092, Balboa, Panama.,Department of Biological Sciences, Dartmouth College, 78 College Street, Hanover, NH 03755, USA
| | - Gerald G Carter
- Smithsonian Tropical Research Institute, Apartado 0843-03092, Balboa, Panama.,Department of Evolution, Ecology and Organismal Biology, The Ohio State University, Columbus, OH, USA
| | - Rachel A Page
- Smithsonian Tropical Research Institute, Apartado 0843-03092, Balboa, Panama
| | - Hannah M Ter Hofstede
- Smithsonian Tropical Research Institute, Apartado 0843-03092, Balboa, Panama.,Department of Biological Sciences, Dartmouth College, 78 College Street, Hanover, NH 03755, USA
| |
Collapse
|
17
|
Geipel I, Amin B, Page RA, Halfwerk W. Does bat response to traffic noise support the misleading cue hypothesis? Behav Ecol 2019. [DOI: 10.1093/beheco/arz148] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Abstract
The world has become a noisier place due to the increase in urbanization. Noise is generally considered an impediment, altering an animal’s behavior through masking or distraction. But noise can also provide useful information about the environment. For animals that rely on natural environmental noise as an indicator of favorable foraging conditions, increasing levels of anthropogenic noise might mislead informed decision-making. Bats use rain noise, a natural environmental cue, to delay their emergence from the roost, presumably to avoid sensory and metabolic costs associated with foraging in heavy rain. Here we tested the “misleading cue hypothesis,” asking whether traffic noise is mistaken for rain noise by bats. Given the acoustic similarity between rain noise and traffic noise, we predicted that bats would confuse the two. We conducted a playback experiment using rain, traffic, and ambient noise at natural roosts of common big-eared bats (Micronycteris microtis, Phyllostomidae) and recorded bat emergence behavior. In contrast to their response to rain noise, the bats did not delay roost emergence in response to traffic noise. Thus, we found that bats were able to discriminate between traffic noise and rain noise and were not misled by similarity in acoustic parameters in the two noise types, when emerging from their roost. Emerging bats did show more exploration flights during traffic noise than during rain noise, but not during ambient noise, suggesting that they perceive traffic noise as a novel acoustic cue. Our data provide new insights into perception of traffic noise by bats.
Collapse
Affiliation(s)
- Inga Geipel
- Smithsonian Tropical Research Institute, Apartado, Balboa, Panamá, República de Panamá
- Wissenschaftskolleg zu Berlin, Institute for Advanced Study, Wallotstraße, Berlin, Germany
| | - Bawan Amin
- Smithsonian Tropical Research Institute, Apartado, Balboa, Panamá, República de Panamá
- Institute of Biology, Leiden University, RA Leiden, the Netherlands
| | - Rachel A Page
- Smithsonian Tropical Research Institute, Apartado, Balboa, Panamá, República de Panamá
| | - Wouter Halfwerk
- Department of Ecological Science, Vrije Universiteit Amsterdam, De Boelelaan, HV Amsterdam, the Netherlands
| |
Collapse
|
18
|
|