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Pedersen MB, Beedholm K, Hubancheva A, Koseva K, Uebel AS, Hochradel K, Madsen PT, Stidsholt L. Clutter resilience via auditory stream segregation in echolocating greater mouse-eared bats. J Exp Biol 2024; 227:jeb246889. [PMID: 38841890 DOI: 10.1242/jeb.246889] [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: 10/16/2023] [Accepted: 05/21/2024] [Indexed: 06/07/2024]
Abstract
Bats use echolocation to navigate and hunt in darkness, and must in that process segregate target echoes from unwanted clutter echoes. Bats may do this by approaching a target at steep angles relative to the plane of the background, utilizing their directional transmission and receiving systems to minimize clutter from background objects, but it remains unknown how bats negotiate clutter that cannot be spatially avoided. Here, we tested the hypothesis that when movement no longer offers spatial release, echolocating bats mitigate clutter by calling at lower source levels and longer call intervals to ease auditory streaming. We trained five greater mouse-eared bats (Myotis myotis) to land on a spherical loudspeaker with two microphones attached. We used a phantom-echo setup, where the loudspeaker/target transmitted phantom clutter echoes by playing back the bats' own calls at time delays of 1, 3 and 5 ms with a virtual target strength 7 dB higher than the physical target. We show that the bats successfully landed on the target, irrespective of the clutter echo delays. Rather than decreasing their source levels, the bats used similar source level distributions in clutter and control trials. Similarly, the bats did not increase their call intervals, but instead used the same distribution of call intervals across control and clutter trials. These observations reject our hypothesis, leading us to conclude that bats display great resilience to clutter via short auditory integration times and acute auditory stream segregation rather than via biosonar adjustments.
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Affiliation(s)
- Michael B Pedersen
- Marine Bioacoustics Lab, Zoophysiology, Department of Biology, Aarhus University, 8000 Aarhus, Denmark
| | - Kristian Beedholm
- Marine Bioacoustics Lab, Zoophysiology, Department of Biology, Aarhus University, 8000 Aarhus, Denmark
| | - Antoniya Hubancheva
- Acoustic and Functional Ecology, Max Planck Institute for Biological Intelligence, 82319 Seewiesen, Germany
- National Museum of Natural History, Bulgarian Academy of Sciences, 1000 Sofia, Bulgaria
| | - Kaloyana Koseva
- Marine Bioacoustics Lab, Zoophysiology, Department of Biology, Aarhus University, 8000 Aarhus, Denmark
| | - Astrid S Uebel
- Marine Bioacoustics Lab, Zoophysiology, Department of Biology, Aarhus University, 8000 Aarhus, Denmark
| | - Klaus Hochradel
- Private University for Health Sciences, Medical Informatics and Technology GmbH, 6060 Hall Tirol, Austria
| | - Peter T Madsen
- Marine Bioacoustics Lab, Zoophysiology, Department of Biology, Aarhus University, 8000 Aarhus, Denmark
| | - Laura Stidsholt
- Marine Bioacoustics Lab, Zoophysiology, Department of Biology, Aarhus University, 8000 Aarhus, Denmark
- Department of Evolutionary Ecology, Leibniz Institute for Zoo and Wildlife Research, 10315 Berlin, Germany
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Macaulay JDJ, Rojano-Doñate L, Ladegaard M, Tougaard J, Teilmann J, Marques TA, Siebert U, Madsen PT. Implications of porpoise echolocation and dive behaviour on passive acoustic monitoring. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2023; 154:1982-1995. [PMID: 37782119 DOI: 10.1121/10.0021163] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Accepted: 09/06/2023] [Indexed: 10/03/2023]
Abstract
Harbour porpoises are visually inconspicuous but highly soniferous echolocating marine predators that are regularly studied using passive acoustic monitoring (PAM). PAM can provide quality data on animal abundance, human impact, habitat use, and behaviour. The probability of detecting porpoise clicks within a given area (P̂) is a key metric when interpreting PAM data. Estimates of P̂ can be used to determine the number of clicks per porpoise encounter that may have been missed on a PAM device, which, in turn, allows for the calculation of abundance and ideally non-biased comparison of acoustic data between habitats and time periods. However, P̂ is influenced by several factors, including the behaviour of the vocalising animal. Here, the common implicit assumption that changes in animal behaviour have a negligible effect on P̂ between different monitoring stations or across time is tested. Using a simulation-based approach informed by acoustic biologging data from 22 tagged harbour porpoises, it is demonstrated that porpoise behavioural states can have significant (up to 3× difference) effects on P̂. Consequently, the behavioural state of the animals must be considered in analysis of animal abundance to avoid substantial over- or underestimation of the true abundance, habitat use, or effects of human disturbance.
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Affiliation(s)
- Jamie Donald John Macaulay
- Department of Biology-Zoophysiology, Aarhus University, C. F. Møllers Allé 3, building 1131, 8000 Aarhus C, Denmark
| | - Laia Rojano-Doñate
- Department of Biology-Zoophysiology, Aarhus University, C. F. Møllers Allé 3, building 1131, 8000 Aarhus C, Denmark
| | - Michael Ladegaard
- Department of Biology-Zoophysiology, Aarhus University, C. F. Møllers Allé 3, building 1131, 8000 Aarhus C, Denmark
| | - Jakob Tougaard
- Department of Ecoscience-Marine Mammal Research, Aarhus University, Frederiksborgvej 399, 4000 Roskilde, Denmark
| | - Jonas Teilmann
- Department of Ecoscience-Marine Mammal Research, Aarhus University, Frederiksborgvej 399, 4000 Roskilde, Denmark
| | - Tiago A Marques
- Centre for Research into Ecological and Environmental Modelling, University of St. Andrews, St. Andrews, Scotland, United Kingdom
| | - Ursula Siebert
- Department of Ecoscience-Marine Mammal Research, Aarhus University, Frederiksborgvej 399, 4000 Roskilde, Denmark
| | - Peter Teglberg Madsen
- Department of Biology-Zoophysiology, Aarhus University, C. F. Møllers Allé 3, building 1131, 8000 Aarhus C, Denmark
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Harley HE, Fellner W, Frances C, Thomas A, Losch B, Newton K, Feuerbach D. Information-seeking across auditory scenes by an echolocating dolphin. Anim Cogn 2022; 25:1109-1131. [PMID: 36018473 DOI: 10.1007/s10071-022-01679-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2022] [Revised: 07/31/2022] [Accepted: 08/08/2022] [Indexed: 11/29/2022]
Abstract
Dolphins gain information through echolocation, a publicly accessible sensory system in which dolphins produce clicks and process returning echoes, thereby both investigating and contributing to auditory scenes. How their knowledge of these scenes contributes to their echoic information-seeking is unclear. Here, we investigate their top-down cognitive processes in an echoic matching-to-sample task in which targets and auditory scenes vary in their decipherability and shift from being completely unfamiliar to familiar. A blind-folded adult male dolphin investigated a target sample positioned in front of a hydrophone to allow recording of clicks, a measure of information-seeking and effort; the dolphin received fish for choosing an object identical to the sample from 3 alternatives. We presented 20 three-object sets, unfamiliar in the first five 18-trial sessions with each set. Performance accuracy and click counts varied widely across sets. Click counts of the four lowest-performance-accuracy/low-discriminability sets (X = 41%) and the four highest-performance-accuracy/high-discriminability sets (X = 91%) were similar at the first sessions' starts and then decreased for both kinds of scenes, although the decrease was substantially greater for low-discriminability sets. In four challenging-but-doable sets, number of clicks remained relatively steady across the 5 sessions. Reduced echoic effort with low-discriminability sets was not due to overall motivation: the differential relationship between click number and object-set discriminability was maintained when difficult and easy trials were interleaved and when objects from originally difficult scenes were grouped with more discriminable objects. These data suggest that dolphins calibrate their echoic information-seeking effort based on their knowledge and expectations of auditory scenes.
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Affiliation(s)
- Heidi E Harley
- Division of Social Sciences, New College of Florida, 5800 Bay Shore Road, Sarasota, FL, 34243, USA. .,The Seas, Epcot®, Walt Disney World® Resorts , Lake Buena Vista, FL, USA.
| | - Wendi Fellner
- The Seas, Epcot®, Walt Disney World® Resorts , Lake Buena Vista, FL, USA
| | - Candice Frances
- Division of Social Sciences, New College of Florida, 5800 Bay Shore Road, Sarasota, FL, 34243, USA.,Basque Center on Cognition, Brain and Language, Donostia, Spain
| | - Amber Thomas
- Division of Social Sciences, New College of Florida, 5800 Bay Shore Road, Sarasota, FL, 34243, USA.,The Seas, Epcot®, Walt Disney World® Resorts , Lake Buena Vista, FL, USA
| | - Barbara Losch
- The Seas, Epcot®, Walt Disney World® Resorts , Lake Buena Vista, FL, USA
| | - Katherine Newton
- Division of Social Sciences, New College of Florida, 5800 Bay Shore Road, Sarasota, FL, 34243, USA.,Department of Fisheries and Wildlife, Oregon State University, Corvallis, USA
| | - David Feuerbach
- The Seas, Epcot®, Walt Disney World® Resorts , Lake Buena Vista, FL, USA
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Branstetter BK, Brietenstein R, Goya G, Tormey M, Wu T, Finneran JJ. Spatial acuity of the bottlenose dolphin (Tursiops truncatus) biosonar system with a bat and human comparison. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2022; 151:3847. [PMID: 35778192 DOI: 10.1121/10.0011676] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Horizontal angular resolution was measured in two bottlenose dolphins using a two-alternative forced-choice, biosonar target discrimination paradigm. The task required a stationary dolphin positioned in a hoop to discriminate two physical targets at a range of 4 m. The angle separating the targets was manipulated to estimate an angular discrimination threshold of 1.5°. In a second experiment, a similar two-target biosonar discrimination task was conducted with one free-swimming dolphin, to test whether its emission beam was a critical factor in discriminating the targets. The spatial separation between two targets was manipulated to measure a discrimination threshold of 6.7 cm. There was a relationship between differences in acoustic signals received at each target and the dolphin's performance. The results of the angular resolution experiment were in good agreement with measures of the minimum audible angle of both dolphins and humans and remarkably similar to measures of angular difference discrimination in echolocating dolphins, bats, and humans. The results suggest that horizontal auditory spatial acuity may be a common feature of the mammalian auditory system rather than a specialized feature exclusive to echolocating auditory predators.
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Affiliation(s)
- Brian K Branstetter
- National Marine Mammal Foundation, 2240 Shelter Island Drive, #200, San Diego, California 92106, USA
| | - Rachel Brietenstein
- National Marine Mammal Foundation, 2240 Shelter Island Drive, #200, San Diego, California 92106, USA
| | - Gavin Goya
- National Marine Mammal Foundation, 2240 Shelter Island Drive, #200, San Diego, California 92106, USA
| | - Megan Tormey
- National Marine Mammal Foundation, 2240 Shelter Island Drive, #200, San Diego, California 92106, USA
| | - Teri Wu
- National Marine Mammal Foundation, 2240 Shelter Island Drive, #200, San Diego, California 92106, USA
| | - James J Finneran
- United States Navy Marine Mammal Program, Naval Information Warfare Center Pacific, San Diego, California 92152, USA
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Macaulay J, Kingston A, Coram A, Oswald M, Swift R, Gillespie D, Northridge S. Passive acoustic tracking of the three‐dimensional movements and acoustic behaviour of toothed whales in close proximity to static nets. Methods Ecol Evol 2022. [DOI: 10.1111/2041-210x.13828] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jamie Macaulay
- Sea Mammal Research Unit Scottish Oceans Institute Scotland, UK
| | - Al Kingston
- Sea Mammal Research Unit Scottish Oceans Institute Scotland, UK
| | - Alex Coram
- Sea Mammal Research Unit Scottish Oceans Institute Scotland, UK
| | - Michael Oswald
- Sea Mammal Research Unit Scottish Oceans Institute Scotland, UK
| | - René Swift
- Sea Mammal Research Unit Scottish Oceans Institute Scotland, UK
| | - Doug Gillespie
- Sea Mammal Research Unit Scottish Oceans Institute Scotland, UK
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Knight K. Porpoises adjust echolocation clicks to distinguish objects from clutter. J Exp Biol 2021. [DOI: 10.1242/jeb.243164] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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