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Taub M, Goldshtein A, Boonman A, Eitan O, Hurme E, Greif S, Yovel Y. What determines the information update rate in echolocating bats. Commun Biol 2023; 6:1187. [PMID: 37989853 PMCID: PMC10663583 DOI: 10.1038/s42003-023-05563-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Accepted: 11/09/2023] [Indexed: 11/23/2023] Open
Abstract
The rate of sensory update is one of the most important parameters of any sensory system. The acquisition rate of most sensory systems is fixed and has been optimized by evolution to the needs of the animal. Echolocating bats have the ability to adjust their sensory update rate which is determined by the intervals between emissions - the inter-pulse intervals (IPI). The IPI is routinely adjusted, but the exact factors driving its regulation are unknown. We use on-board audio recordings to determine how four species of echolocating bats with different foraging strategies regulate their sensory update rate during commute flights. We reveal strong correlations between the IPI and various echolocation and movement parameters. Specifically, the update rate increases when the signals' peak-energy frequency and intensity increases while the update rate decreases when flight speed and altitude increases. We suggest that bats control their information update rate according to the behavioral mode they are engaged in, while always maintaining sensory continuity. Specifically, we suggest that bats apply two modes of attention during commute flights. Our data moreover suggests that bats emit echolocation signals at accurate intervals without the need for external feedback.
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Affiliation(s)
- Mor Taub
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv, 6997801, Israel
| | - Aya Goldshtein
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv, 6997801, Israel
- Department of Collective Behaviour, Max Planck Institute of Animal Behaviour, Konstanz, 78464, Germany
- Centre for the Advanced Study of Collective Behaviour, University of Konstanz, Konstanz, Germany
- Department of Biology, University of Konstanz, Konstanz, Germany
| | - Arjan Boonman
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv, 6997801, Israel
| | - Ofri Eitan
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv, 6997801, Israel
| | - Edward Hurme
- Department of Migration, Max Planck Institute of Animal Behavior, Radolfzell, Germany
- Centre for the Advanced Study of Collective Behaviour, University of Konstanz, Konstanz, Germany
| | - Stefan Greif
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv, 6997801, Israel
| | - Yossi Yovel
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv, 6997801, Israel.
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, 6997801, Israel.
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2
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Eitan O, Taub M, Boonman A, Zviran A, Tourbabin V, Weiss AJ, Yovel Y. Echolocating bats rapidly adjust their mouth gape to control spatial acquisition when scanning a target. BMC Biol 2022; 20:282. [PMID: 36527053 PMCID: PMC9758934 DOI: 10.1186/s12915-022-01487-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Accepted: 11/30/2022] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND As well known to any photographer, controlling the "field of view" offers an extremely powerful mechanism by which to adjust target acquisition. Only a few natural sensory systems can actively control their field of view (e.g., dolphins, whales, and bats). Bats are known for their active sensing abilities and modify their echolocation signals by actively controlling their spectral and temporal characteristics. Less is known about bats' ability to actively modify their bio-sonar field of view. RESULTS We show that Pipistrellus kuhlii bats rapidly narrow their sensory field of view (i.e., their bio-sonar beam) when scanning a target. On-target vertical sonar beams were twofold narrower than off-target beams. Continuous measurements of the mouth gape of free-flying bats revealed that they control their bio-sonar beam by a ~3.6 mm widening of their mouth gape: namely, bats open their mouth to narrow the beam and vice versa. CONCLUSIONS Bats actively and rapidly control their echolocation vertical beam width by modifying their mouth gape. We hypothesize that narrowing their vertical beam narrows the zone of ensonification when estimating the elevation of a target. In other words, bats open their mouth to improve sensory localization.
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Affiliation(s)
- Ofri Eitan
- grid.12136.370000 0004 1937 0546School of Zoology, Faculty of Life Sciences, Tel Aviv University, 6997801 Tel Aviv, Israel
| | - Mor Taub
- grid.12136.370000 0004 1937 0546School of Zoology, Faculty of Life Sciences, Tel Aviv University, 6997801 Tel Aviv, Israel
| | - Arjan Boonman
- grid.12136.370000 0004 1937 0546School of Zoology, Faculty of Life Sciences, Tel Aviv University, 6997801 Tel Aviv, Israel
| | - Amir Zviran
- grid.12136.370000 0004 1937 0546School of Zoology, Faculty of Life Sciences, Tel Aviv University, 6997801 Tel Aviv, Israel ,grid.12136.370000 0004 1937 0546The School of Electrical Engineering, the Iby and Aladar Fleischman Faculty of Engineering, Tel Aviv University, 6997801 Tel Aviv, Israel
| | - Vladimir Tourbabin
- grid.7489.20000 0004 1937 0511Department of Electrical and Computer Engineering, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Anthony J. Weiss
- grid.12136.370000 0004 1937 0546The School of Electrical Engineering, the Iby and Aladar Fleischman Faculty of Engineering, Tel Aviv University, 6997801 Tel Aviv, Israel
| | - Yossi Yovel
- grid.12136.370000 0004 1937 0546School of Zoology, Faculty of Life Sciences, Tel Aviv University, 6997801 Tel Aviv, Israel ,grid.12136.370000 0004 1937 0546Sagol School of Neuroscience, Tel Aviv University, 6997801 Tel Aviv, Israel ,grid.12136.370000 0004 1937 0546School of Mechanical Engineering, the Iby and Aladar Fleischman Faculty of Engineering, Tel Aviv University, 6997801 Tel Aviv, Israel ,grid.12136.370000 0004 1937 0546The Steinhardt Museum of Natural History, National Research Center for Biodiversity Studies, Tel-Aviv University, Tel Aviv, Israel
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3
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Abstract
Bats rely on echolocation for operating in dim light or dark conditions. Accordingly, most research on echolocation is performed under dark conditions with a few exceptions. Bat species that emerge to forage before sunset have been shown to use echolocation even in relatively high light levels1-3. It has been argued that for insectivorous bats, as light levels decrease, echolocation rapidly becomes advantageous over vision for detecting tiny insects during dusk or dawn2 and that information from the two sensory modalities is integrated4,5. Functional use of echolocation in broad daylight in insectivorous bats has been scarcely reported6,7. Here, we report functional use of echolocation in broad daylight in highly visual fruit bats.
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Affiliation(s)
- Ofri Eitan
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv 6997801, Israel.
| | - Maya Weinberg
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Sasha Danilovich
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Yuval Barkai
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Reut Assa
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Yossi Yovel
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv 6997801, Israel; Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel; School of Mechanical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv 6997801, Israel
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4
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Zigelman R, Eitan O, Mazar O, Weiss A, Yovel Y. A bio-mimetic miniature drone for real-time audio based short-range tracking. PLoS Comput Biol 2022; 18:e1009936. [PMID: 35259156 PMCID: PMC8932603 DOI: 10.1371/journal.pcbi.1009936] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 03/18/2022] [Accepted: 02/18/2022] [Indexed: 11/29/2022] Open
Abstract
One of the most difficult sensorimotor behaviors exhibited by flying animals is the ability to track another flying animal based on its sound emissions. From insects to mammals, animals display this ability in order to localize and track conspecifics, mate or prey. The pursuing individual must overcome multiple non-trivial challenges including the detection of the sounds emitted by the target, matching the input received by its (mostly) two sensors, localizing the direction of the sound target in real time and then pursuing it. All this has to be done rapidly as the target is constantly moving. In this project, we set to mimic this ability using a physical bio-mimetic autonomous drone. We equipped a miniature commercial drone with our in-house 2D sound localization electronic circuit which uses two microphones (mimicking biological ears) to localize sound signals in real-time and steer the drone in the horizontal plane accordingly. We focus on bat signals because bats are known to eavesdrop on conspecifics and follow them, but our approach could be generalized to other biological signals and other man-made signals. Using two different experiments, we show that our fully autonomous aviator can track the position of a moving sound emitting target and pursue it in real-time. Building an actual robotic-agent, forced us to deal with real-life difficulties which also challenge animals. We thus discuss the similarities and differences between our and the biological approach. Animals solve problems that are considered very difficult for human engineers. In this study, we aimed to mimic animals’ ability to localize and track a moving sound source in real time. We do so using a bio-inspired approach by developing a miniature electronic circuit with two ear-like microphones and a micro-processor that is placed on a miniature drone. The circuit detects ultrasonic signals that are typical for echolocating bats and it uses its two ‘ears’ to estimate the azimuth of the sound source and to steer the drone accordingly. The system is completely autonomous without external human intervention. We focus on bat signals as a proof of concept, but we can alter the electronics to suit other biological signals. Future research will include groups of multiple drones moving together based on acoustic signals as bats and some birds can do in nature.
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Affiliation(s)
- Roei Zigelman
- Electrical Engineering Department, Tel Aviv University, Tel Aviv, Israel
| | - Ofri Eitan
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Omer Mazar
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Anthony Weiss
- Electrical Engineering Department, Tel Aviv University, Tel Aviv, Israel
| | - Yossi Yovel
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
- School of Mechanical Engineering, The Fleischman Faculty of Engineering, Tel Aviv University, Tel Aviv, Israel
- * E-mail:
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5
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Egert-Berg K, Handel M, Goldshtein A, Eitan O, Borissov I, Yovel Y. Fruit bats adjust their foraging strategies to urban environments to diversify their diet. BMC Biol 2021; 19:123. [PMID: 34134697 PMCID: PMC8210355 DOI: 10.1186/s12915-021-01060-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 05/30/2021] [Indexed: 11/18/2022] Open
Abstract
Background Urbanization is one of the most influential processes on our globe, putting a great number of species under threat. Some species learn to cope with urbanization, and a few even benefit from it, but we are only starting to understand how they do so. In this study, we GPS tracked Egyptian fruit bats from urban and rural populations to compare their movement and foraging in urban and rural environments. Because fruit trees are distributed differently in these two environments, with a higher diversity in urban environments, we hypothesized that foraging strategies will differ too. Results When foraging in urban environments, bats were much more exploratory than when foraging in rural environments, visiting more sites per hour and switching foraging sites more often on consecutive nights. By doing so, bats foraging in settlements diversified their diet in comparison to rural bats, as was also evident from their choice to often switch fruit species. Interestingly, the location of the roost did not dictate the foraging grounds, and we found that many bats choose to roost in the countryside but nightly commute to and forage in urban environments. Conclusions Bats are unique among small mammals in their ability to move far rapidly. Our study is an excellent example of how animals adjust to environmental changes, and it shows how such mobile mammals might exploit the new urban fragmented environment that is taking over our landscape. Supplementary Information The online version contains supplementary material available at 10.1186/s12915-021-01060-x.
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Affiliation(s)
- Katya Egert-Berg
- Sagol School of Neuroscience, Tel Aviv University, 6997801, Tel Aviv, Israel
| | - Michal Handel
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, 6997801, Tel Aviv, Israel
| | - Aya Goldshtein
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, 6997801, Tel Aviv, Israel
| | - Ofri Eitan
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, 6997801, Tel Aviv, Israel
| | - Ivailo Borissov
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, 6997801, Tel Aviv, Israel
| | - Yossi Yovel
- Sagol School of Neuroscience, Tel Aviv University, 6997801, Tel Aviv, Israel. .,School of Zoology, Faculty of Life Sciences, Tel Aviv University, 6997801, Tel Aviv, Israel. .,Wissenschaftskolleg zu Berlin, Berlin, Germany.
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6
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Krivoruchko K, Goldshtein A, Boonman A, Eitan O, Ben-Simon J, Thong VD, Yovel Y. Fireflies produce ultrasonic clicks during flight as a potential aposematic anti-bat signal. iScience 2021; 24:102194. [PMID: 33733061 PMCID: PMC7937554 DOI: 10.1016/j.isci.2021.102194] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 11/29/2020] [Accepted: 02/10/2021] [Indexed: 11/21/2022] Open
Abstract
Fireflies are known for emitting light signals for intraspecific communication. However, in doing so, they reveal themselves to many potential nocturnal predators from a large distance. Therefore, many fireflies evolved unpalatable compounds and probably use their light signals as anti-predator aposematic signals. Fireflies are occasionally attacked by predators despite their warning flashes. Bats are among the most substantial potential firefly predators. Using their echolocation, bats might detect a firefly from a short distance and attack it in between two flashes. We thus aimed to examine whether fireflies use additional measures of warning, specifically focusing on sound signals. We recorded four species from different genera of fireflies in Vietnam and Israel and found that all of them generated ultrasonic clicks centered around bats' hearing range. Clicks were synchronized with the wingbeat and are probably produced by the wings. We hypothesize that ultrasonic clicks can serve as part of a multimodal aposematic display.
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Affiliation(s)
- Ksenia Krivoruchko
- Department of Neuroscience, Rappaport Research Institute and Faculty of Medicine, Technion, Haifa, Israel
| | - Aya Goldshtein
- School of Zoology, Faculty of Life sciences, Tel Aviv University, Tel Aviv, Israel
| | - Arjan Boonman
- School of Zoology, Faculty of Life sciences, Tel Aviv University, Tel Aviv, Israel
| | - Ofri Eitan
- School of Zoology, Faculty of Life sciences, Tel Aviv University, Tel Aviv, Israel
| | - Jonathan Ben-Simon
- School of Zoology, Faculty of Life sciences, Tel Aviv University, Tel Aviv, Israel
| | - Vu Dinh Thong
- Institute of Ecology and Biological Resources, VAST, Cầu Giấy, Hà Nội, Vietnam
- Graduate University of Science and Technology, VAST, Cầu Giấy, Hà Nội, Vietnam
| | - Yossi Yovel
- School of Zoology, Faculty of Life sciences, Tel Aviv University, Tel Aviv, Israel
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
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7
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Boonman A, Rieger I, Amichai E, Greif S, Eitan O, Goldshtein A, Yovel Y. Echolocating bats can adjust sensory acquisition based on internal cues. BMC Biol 2020; 18:166. [PMID: 33167988 PMCID: PMC7654590 DOI: 10.1186/s12915-020-00904-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Accepted: 10/20/2020] [Indexed: 12/04/2022] Open
Abstract
Background Sensory systems acquire both external and internal information to guide behavior. Adjustments based on external input are much better documented and understood than internal-based sensory adaptations. When external input is not available, idiothetic—internal—cues become crucial for guiding behavior. Here, we take advantage of the rapid sensory adjustments exhibited by bats in order to study how animals rely on internal cues in the absence of external input. Constant frequency echolocating bats are renowned for their Doppler shift compensation response used to adjust their emission frequency in order to optimize sensing. Previous studies documented the importance of external echoes for this response. Results We show that the Doppler compensation system works even without external feedback. Bats experiencing accelerations in an echo-free environment exhibited an intact compensation response. Moreover, using on-board GPS tags on free-flying bats in the wild, we demonstrate that the ability to perform Doppler shift compensation response based on internal cues might be essential in real-life when echo feedback is not available. Conclusions We thus show an ecological need for using internal cues as well as an ability to do so. Our results illustrate the robustness of one particular sensory behavior; however, we suggest this ability to rely on different streams of information (i.e., internal or external) is probably relevant for many sensory behaviors.
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Affiliation(s)
- Arjan Boonman
- School of Zoology, Faculty of Life Sciences, Tel-Aviv University, 6997801, Tel Aviv, Israel
| | - Itai Rieger
- School of Zoology, Faculty of Life Sciences, Tel-Aviv University, 6997801, Tel Aviv, Israel
| | - Eran Amichai
- School of Zoology, Faculty of Life Sciences, Tel-Aviv University, 6997801, Tel Aviv, Israel. .,Ecology, Evolution, Environment and Society Graduate Program, Dartmouth College, Hanover, NH, 03755, USA.
| | - Stefan Greif
- School of Zoology, Faculty of Life Sciences, Tel-Aviv University, 6997801, Tel Aviv, Israel.,Sagol School of Neuroscience, Tel-Aviv University, 6997801, Tel Aviv, Israel
| | - Ofri Eitan
- School of Zoology, Faculty of Life Sciences, Tel-Aviv University, 6997801, Tel Aviv, Israel
| | - Aya Goldshtein
- School of Zoology, Faculty of Life Sciences, Tel-Aviv University, 6997801, Tel Aviv, Israel
| | - Yossi Yovel
- School of Zoology, Faculty of Life Sciences, Tel-Aviv University, 6997801, Tel Aviv, Israel. .,Sagol School of Neuroscience, Tel-Aviv University, 6997801, Tel Aviv, Israel. .,School of Mechanical Engineering, Faculty of Engineering, Tel-Aviv University, 6997801, Tel Aviv, Israel.
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8
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Goldshtein A, Handel M, Eitan O, Bonstein A, Shaler T, Collet S, Greif S, Medellín RA, Emek Y, Korman A, Yovel Y. Reinforcement Learning Enables Resource Partitioning in Foraging Bats. Curr Biol 2020; 30:4096-4102.e6. [PMID: 32822610 PMCID: PMC7575196 DOI: 10.1016/j.cub.2020.07.079] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 05/09/2020] [Accepted: 07/27/2020] [Indexed: 10/29/2022]
Abstract
Every evening, from late spring to mid-summer, tens of thousands of hungry lactating female lesser long-nosed bats (Leptonycteris yerbabuenae) emerge from their roost and navigate over the Sonoran Desert, seeking for nectar and pollen [1, 2]. The bats roost in a huge maternal colony that is far from the foraging grounds but allows their pups to thermoregulate [3] while the mothers are foraging. Thus, the mothers have to fly tens of kilometers to the foraging sites-fields with thousands of Saguaro cacti [4, 5]. Once at the field, they must compete with many other bats over the same flowering cacti. Several solutions have been suggested for this classical foraging task of exploiting a resource composed of many renewable food sources whose locations are fixed. Some animals randomly visit the food sources [6], and some actively defend a restricted foraging territory [7-11] or use simple forms of learning, such as "win-stay lose-switch" strategy [12]. Many species have been suggested to follow a trapline, that is, to revisit the food sources in a repeating ordered manner [13-22]. We thus hypothesized that lesser long-nosed bats would visit cacti in a sequenced manner. Using miniature GPS devices, aerial imaging, and video recordings, we tracked the full movement of the bats and all of their visits to their natural food sources. Based on real data and evolutionary simulations, we argue that the bats use a reinforcement learning strategy that requires minimal memory to create small, non-overlapping cacti-cores and exploit nectar efficiently, without social communication.
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Affiliation(s)
- Aya Goldshtein
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Michal Handel
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Ofri Eitan
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Afrine Bonstein
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Talia Shaler
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Simon Collet
- The Research Institute on the Foundations of Computer Science (IRIF), CNRS and University of Paris, Paris 75013, France
| | - Stefan Greif
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Rodrigo A Medellín
- Departamento de Ecología de la Biodiversidad, Instituto de Ecología, Universidad Nacional Autónoma de México, Ciudad de México 04510, México
| | - Yuval Emek
- Faculty of Industrial Engineering and Management, Technion - Israel Institute of Technology, Haifa 3200003, Israel
| | - Amos Korman
- The Research Institute on the Foundations of Computer Science (IRIF), CNRS and University of Paris, Paris 75013, France.
| | - Yossi Yovel
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv 6997801, Israel; Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel.
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9
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Abstract
Animal flight noise can serve as an inspiration to engineering solutions to wind-noise problems in planes or wind turbines. Here we investigate the acoustics of wingbeats in birds and bats by co-registering wing-movement in natural flight with acoustic noise. To understand the relationships between wing movement and acoustics, we conducted additional acoustic measurements of single moving wings and other moving surfaces with accurately tracked motion paths. We found a correlation between wing-surface area and the sound pressure level of wingbeats; with bats tending to produce lower levels than birds. Measuring moving wings in isolation showed that a downstroke toward a microphone causes negative sound pressure that flips back into positive pressure at the reversal to the upstroke. The flip back to positive pressure is unrelated to the action of the upstroke, but occurs when the downward motion is halted. If the microphone is positioned above the downward wingbeat, then sound pressure instead quickly rises during the downward motion of the wing. The phase pattern of the impulse created by the wingbeat varies systematically with recording-angle. The curvature of the wing appears to be a determinant of the average frequency of the acoustic impulse. Our findings can be used to predict the acoustics of smaller flying animals where repetition pitch of similar underlying impulses, repeated at much higher wingbeat-rates become dominant.
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Affiliation(s)
- Arjan Boonman
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Yossi Yovel
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel
- School of Mechanical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Ofri Eitan
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
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10
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Abstract
Sensing from a moving platform is challenging for both man-made machines and animals. Animals' heads jitter during movement, so if the sensors they carry are not stabilized, any spatial estimation might be biased. Flying animals, like bats, seriously suffer from this problem because flapping flight induces rapid changes in acceleration which moves the body up and down. For echolocating bats, the problem is crucial. Because they emit a sound to sense the world, an unstable head means sound energy pointed in the wrong direction. It is unknown how bats mitigate this problem. By tracking the head and body of flying fruit bats, we show that they stabilize their heads, accurately maintaining a fixed acoustic-gaze relative to a target. Bats can solve the stabilization task even in complete darkness using only echo-based information. Moreover, the bats point their echolocation beam below the target and not towards it, a strategy that should result in better estimations of target elevation.
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Affiliation(s)
- O Eitan
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
| | - G Kosa
- Intelligent Medical Micro/Nano Systems Group, University Hospital of Basel, Basel, Switzerland
| | - Y Yovel
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv 6997801, Israel.,Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel.,School of Mechanical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv 6997801, Israel
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11
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Egert-Berg K, Hurme ER, Greif S, Goldstein A, Harten L, Herrera M LG, Flores-Martínez JJ, Valdés AT, Johnston DS, Eitan O, Borissov I, Shipley JR, Medellin RA, Wilkinson GS, Goerlitz HR, Yovel Y. Resource Ephemerality Drives Social Foraging in Bats. Curr Biol 2018; 28:3667-3673.e5. [PMID: 30393034 DOI: 10.1016/j.cub.2018.09.064] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Revised: 08/08/2018] [Accepted: 09/26/2018] [Indexed: 11/18/2022]
Abstract
Observations of animals feeding in aggregations are often interpreted as events of social foraging, but it can be difficult to determine whether the animals arrived at the foraging sites after collective search [1-4] or whether they found the sites by following a leader [5, 6] or even independently, aggregating as an artifact of food availability [7, 8]. Distinguishing between these explanations is important, because functionally, they might have very different consequences. In the first case, the animals could benefit from the presence of conspecifics, whereas in the second and third, they often suffer from increased competition [3, 9-13]. Using novel miniature sensors, we recorded GPS tracks and audio of five species of bats, monitoring their movement and interactions with conspecifics, which could be inferred from the audio recordings. We examined the hypothesis that food distribution plays a key role in determining social foraging patterns [14-16]. Specifically, this hypothesis predicts that searching for an ephemeral resource (whose distribution in time or space is hard to predict) is more likely to favor social foraging [10, 13-15] than searching for a predictable resource. The movement and social interactions differed between bats foraging on ephemeral versus predictable resources. Ephemeral species changed foraging sites and showed large temporal variation nightly. They aggregated with conspecifics as was supported by playback experiments and computer simulations. In contrast, predictable species were never observed near conspecifics and showed high spatial fidelity to the same foraging sites over multiple nights. Our results suggest that resource (un)predictability influences the costs and benefits of social foraging.
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Affiliation(s)
- Katya Egert-Berg
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Edward R Hurme
- Department of Biology, University of Maryland, College Park, MD 20742, USA
| | - Stefan Greif
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv 6997801, Israel; Acoustic and Functional Ecology, Max Planck Institute for Ornithology, Seewiesen, Germany
| | - Aya Goldstein
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Lee Harten
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Luis Gerardo Herrera M
- Estación de Biología de Chamela, Instituto de Biología, Universidad Nacional Autónoma de México, San Patricio, Jalisco 48980, México
| | - José Juan Flores-Martínez
- Laboratorio de Sistemas de Información Geográfica, Instituto de Biología, Universidad Nacional Autónoma de México, Ciudad de México 04510, México
| | - Andrea T Valdés
- Posgrado en Ciencias Biológicas, Instituto de Biología, Universidad Nacional Autónoma de México, Ciudad de México 04510, México
| | - Dave S Johnston
- H.T. Harvey & Associates, Los Gatos, CA, USA; Department of Biology, San Jose State University, San Jose, CA, USA
| | - Ofri Eitan
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Ivo Borissov
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Jeremy Ryan Shipley
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, USA
| | - Rodrigo A Medellin
- Departamento de Ecología de la Biodiversidad, Instituto de Ecología, Universidad, Nacional Autónoma de México, Ciudad de México 04510, México
| | - Gerald S Wilkinson
- Department of Biology, University of Maryland, College Park, MD 20742, USA
| | - Holger R Goerlitz
- Acoustic and Functional Ecology, Max Planck Institute for Ornithology, Seewiesen, Germany
| | - Yossi Yovel
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel; School of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv 6997801, Israel.
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Danilovich S, Krishnan A, Lee WJ, Borrisov I, Eitan O, Kosa G, Moss CF, Yovel Y. Bats regulate biosonar based on the availability of visual information. Curr Biol 2016; 25:R1124-5. [PMID: 26654368 DOI: 10.1016/j.cub.2015.11.003] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Sasha Danilovich
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel.
| | - Anand Krishnan
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Wu-Jung Lee
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Ivailo Borrisov
- Department of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Ofri Eitan
- Department of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Gabor Kosa
- School of Mechanical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Cynthia F Moss
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD 21218, USA; Department of Neuroscience, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Yossi Yovel
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel; Department of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv 6997801, Israel.
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Kounitsky P, Rydell J, Amichai E, Boonman A, Eitan O, Weiss AJ, Yovel Y. Bats adjust their mouth gape to zoom their biosonar field of view. Proc Natl Acad Sci U S A 2015; 112:6724-9. [PMID: 25941395 PMCID: PMC4450403 DOI: 10.1073/pnas.1422843112] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
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.
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Affiliation(s)
- Pavel Kounitsky
- Department of Zoology, Faculty of Life Sciences, School of Electrical Engineering, The Iby and Aladar Fleischman Faculty of Engineering, and
| | - Jens Rydell
- Department of Zoology, Faculty of Life Sciences
| | | | | | - Ofri Eitan
- Department of Zoology, Faculty of Life Sciences
| | - Anthony J Weiss
- School of Electrical Engineering, The Iby and Aladar Fleischman Faculty of Engineering, and
| | - Yossi Yovel
- Department of Zoology, Faculty of Life Sciences, Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel
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