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Fernández Y, Dowdy NJ, Conner WE. High duty cycle moth sounds jam bat echolocation: bats counter with compensatory changes in buzz duration. J Exp Biol 2022; 225:jeb244187. [PMID: 36111562 PMCID: PMC9637272 DOI: 10.1242/jeb.244187] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Accepted: 08/23/2022] [Indexed: 10/05/2023]
Abstract
Tiger moth species vary greatly in the number of clicks they produce and the resultant duty cycle. Signals with higher duty cycles are expected to more effectively interfere with bat sonar. However, little is known about the minimum duty cycle of tiger moth signals for sonar jamming. Is there a threshold that allows us to classify moths as acoustically aposematic versus sonar jammers based on their duty cycles? We performed playback experiments with three wild-caught adult male bats, Eptesicus fuscus. Bat attacks on tethered moths were challenged using acoustic signals of Bertholdia trigona with modified duty cycles ranging from 0 to 46%. We did not find evidence for a duty cycle threshold; rather, the ability to jam the bat's sonar was a continuous function of duty cycle consistent with a steady increase in the number of clicks arriving during a critical signal processing time window just prior to the arrival of an echo. The proportion of successful captures significantly decreased as the moth duty cycle increased. Our findings suggest that moths cannot be unambiguously classified as acoustically aposematic or sonar jammers based solely on duty cycle. Bats appear to compensate for sonar jamming by lengthening the duration of their terminal buzz and they are more successful in capturing moths when they do so. In contrast to previous findings for bats performing difficult spatial tasks, the number of sonar sound groups decreased in response to high duty cycles and did not affect capture success.
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Affiliation(s)
- Yohami Fernández
- Department of Biology, Wake Forest University, 1834 Wake Forest Road, Winston-Salem, NC 27109, USA
| | - Nicolas J. Dowdy
- Department of Biology, Wake Forest University, 1834 Wake Forest Road, Winston-Salem, NC 27109, USA
- Department of Zoology, Milwaukee Public Museum, 800 West Wells Street, Milwaukee, WI 53233, USA
| | - William E. Conner
- Department of Biology, Wake Forest University, 1834 Wake Forest Road, Winston-Salem, NC 27109, USA
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2
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Knörnschild M, Fernandez AA. Do Bats Have the Necessary Prerequisites for Symbolic Communication? Front Psychol 2020; 11:571678. [PMID: 33262725 PMCID: PMC7688458 DOI: 10.3389/fpsyg.2020.571678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 10/12/2020] [Indexed: 11/20/2022] Open
Abstract
Training animals such as apes, gray parrots, or dolphins that communicate via arbitrary symbols with humans has revealed astonishing mental capacities that may have otherwise gone unnoticed. Albeit bats have not yet been trained to communicate via symbols with humans, we are convinced that some species, especially captive Pteropodid bats ("flying foxes"), show the potential to master this cognitive task. Here, we briefly review what is known about bats' cognitive skills that constitute relevant prerequisites for symbolic communication with humans. We focus on social learning in general, trainability by humans, associative learning from humans, imitation, vocal production learning and usage learning, and social knowledge. Moreover, we highlight potential training paradigms that could be used to elicit simple "symbolic" bat-human communication, i.e., training bats to select arbitrary symbols on a touchscreen to elicit a desired behavior of the human caregiver. Touchscreen-proficient bats could participate in cognition research, e.g., to study their numerical competence or categorical perception, to further elucidate how nonhuman animals learn and perceive the world.
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Affiliation(s)
- Mirjam Knörnschild
- Museum für Naturkunde, Leibniz-Institute for Evolution and Biodiversity Science, Berlin, Germany
- Animal Behavior Lab, Freie Universität, Berlin, Germany
- Smithsonian Tropical Research Institute, Ancón, Panama
| | - Ahana A. Fernandez
- Museum für Naturkunde, Leibniz-Institute for Evolution and Biodiversity Science, Berlin, Germany
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Hernández-Montero JR, Reusch C, Simon R, Schöner CR, Kerth G. Free-ranging bats combine three different cognitive processes for roost localization. Oecologia 2020; 192:979-988. [PMID: 32236689 PMCID: PMC7165157 DOI: 10.1007/s00442-020-04634-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Accepted: 03/12/2020] [Indexed: 01/02/2023]
Abstract
Animals have evolved different cognitive processes to localize crucial resources that are difficult to find. Relevant cognitive processes such as associative learning and spatial memory have commonly been studied in a foraging related context under controlled laboratory conditions. However, in natural environments, animals can use multiple cognitive processes to localize resources. In this field study, we used a pairwise choice experiment and automatic roost monitoring to assess how individually marked, free-ranging Bechstein’s bats belonging to two different colonies use associative learning, spatial memory and social information when localizing suitable day roosts. To our knowledge, this study tests for the first time how associative learning, spatial memory and social information are used in the process of roost localization in bats under the natural conditions. We show that, when searching for new roosts, bats used associative learning to discriminate between suitable and unsuitable roosts. For re-localizing previously occupied roosts, bats used spatial memory rather than associative learning. Moreover, bats significantly improved the localization of suitable unfamiliar roosts and tended to increase their accuracy to re-localize previously occupied day roosts using social information. Our field experiments suggest that Bechstein’s bats make hierarchical use of different cognitive processes when localizing day roosts. More generally, our study underlines that evaluating different cues under natural conditions is fundamental to understanding how natural selection has shaped the cognitive processes used for localizing resources.
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Affiliation(s)
- Jesús R Hernández-Montero
- Zoological Institute and Museum, Applied Zoology and Nature Conservation, Greifswald University, Loitzerstraße 26, 17489, Greifswald, Germany.
| | - Christine Reusch
- Zoological Institute and Museum, Applied Zoology and Nature Conservation, Greifswald University, Loitzerstraße 26, 17489, Greifswald, Germany
| | - Ralph Simon
- Department of Ecological Science/Animal Ecology, Faculty of Earth and Life Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Caroline Regina Schöner
- Zoological Institute and Museum, Applied Zoology and Nature Conservation, Greifswald University, Loitzerstraße 26, 17489, Greifswald, Germany
| | - Gerald Kerth
- Zoological Institute and Museum, Applied Zoology and Nature Conservation, Greifswald University, Loitzerstraße 26, 17489, Greifswald, Germany
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Abstract
Once a year about 15 million Mexican free-tailed bats (Tadarida brasiliensis) migrate up to 1,500 kilometers from wintering grounds, seamlessly flying over the Mexican border to enter the United States. Their destination is the Bracken Cave in southern Texas, which will be their summer home between the months of March through October. While residing there, these bats emerge every night at dusk from the narrow 100-foot-wide opening of this enormous cave and begin their nightly commute to foraging grounds located up to 50 kilometers away. Upon arrival, they will spend the night hunting for insects in mid-air while providing a valuable service to local farmers by keeping crop pests in check. Close to the break of dawn, as the night of hunting comes to an end, these bats will begin making their trip back to the roost.
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Affiliation(s)
- Daria Genzel
- Department of Bioengineering, UC Berkeley, Berkeley, CA 94708, United States; Helen Wills Neuroscience Institute, UC Berkeley, Berkeley, CA 94708, United States
| | - Yossi Yovel
- Department of Zoology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel; Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 69978, Israel
| | - Michael M Yartsev
- Department of Bioengineering, UC Berkeley, Berkeley, CA 94708, United States; Helen Wills Neuroscience Institute, UC Berkeley, Berkeley, CA 94708, United States.
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Yu C, Luo J, Wohlgemuth M, Moss CF. Echolocating bats inspect and discriminate landmark features to guide navigation. ACTA ACUST UNITED AC 2019; 222:jeb.191965. [PMID: 30936268 DOI: 10.1242/jeb.191965] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Accepted: 03/26/2019] [Indexed: 11/20/2022]
Abstract
Landmark-guided navigation is a common behavioral strategy for way-finding, yet prior studies have not examined how animals collect sensory information to discriminate landmark features. We investigated this question in animals that rely on active sensing to guide navigation. Four echolocating bats (Eptesicus fuscus) were trained to use an acoustic landmark to find and navigate through a net opening for a food reward. In experimental trials, an object serving as a landmark was placed adjacent to a net opening and an object serving as a distractor was placed next to a barrier (covered opening). The location of the opening, barrier and objects were moved between trials, but the spatial relationships between the landmark and opening, and between the distractor and barrier were maintained. In probe trials, the landmark was placed next to a barrier, while the distractor was placed next to the opening, to test whether the bats relied on the landmark to guide navigation. Vocal and flight behaviors were recorded with an array of ultrasound microphones and high-speed infrared motion-capture cameras. All bats successfully learned to use the landmark to guide navigation through the net opening. Probe trials yielded an increase in both the time to complete the task and the number of net crashes, confirming that the bats relied largely on the landmark to find the net opening. Further, landmark acoustic distinctiveness influenced performance in probe trials and sonar inspection behaviors. Analyses of the animals' vocal behaviors also revealed differences between call features of bats inspecting landmarks compared with distractors, suggesting increased sonar attention to objects used to guide navigation.
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Affiliation(s)
- Chao Yu
- Department of Psychological and Brain Sciences, Johns Hopkins University, 3400 N Charles Street, Baltimore, MD 21218, USA
| | - Jinhong Luo
- Department of Psychological and Brain Sciences, Johns Hopkins University, 3400 N Charles Street, Baltimore, MD 21218, USA
| | - Melville Wohlgemuth
- Department of Psychological and Brain Sciences, Johns Hopkins University, 3400 N Charles Street, Baltimore, MD 21218, USA
| | - Cynthia F Moss
- Department of Psychological and Brain Sciences, Johns Hopkins University, 3400 N Charles Street, Baltimore, MD 21218, USA
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Zimmer MR, Schmitz AE, Dietrich MO. Activation of Agrp neurons modulates memory-related cognitive processes in mice. Pharmacol Res 2019; 141:303-309. [PMID: 30610962 PMCID: PMC6400640 DOI: 10.1016/j.phrs.2018.12.024] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Revised: 12/27/2018] [Accepted: 12/27/2018] [Indexed: 01/05/2023]
Abstract
Hypothalamic Agrp neurons are critical regulators of food intake in adult mice. In addition to food intake, these neurons have been involved in other cognitive processes, such as the manifestation of stereotyped behaviors. Here, we evaluated the extent to which Agrp neurons modulate mouse behavior in spatial memory-related tasks. We found that activation of Agrp neurons did not affect spatial learning but altered behavioral flexibility using a modified version of the Barnes Maze task. Furthermore, using the Y-maze test to probe working memory, we found that chemogenetic activation of Agrp neurons reduced spontaneous alternation behavior mediated by the neuropeptide Y receptor-5 signaling. These findings suggest novel functional properties of Agrp neurons in memory-related cognitive processes.
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Affiliation(s)
- Marcelo R Zimmer
- Program in Integrative Cell Signaling and Neurobiology of Metabolism, Department of Comparative Medicine, Yale University School of Medicine, New Haven, CT, 06520, USA; Graduate Program in Biochemistry, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, 90035, Brazil
| | - Ariana E Schmitz
- Program in Integrative Cell Signaling and Neurobiology of Metabolism, Department of Comparative Medicine, Yale University School of Medicine, New Haven, CT, 06520, USA; Department of Biochemistry, Universidade Federal de Santa Catarina, Florianópolis, SC, 88040, Brazil
| | - Marcelo O Dietrich
- Program in Integrative Cell Signaling and Neurobiology of Metabolism, Department of Comparative Medicine, Yale University School of Medicine, New Haven, CT, 06520, USA; Department of Neuroscience, Yale University School of Medicine, New Haven, CT, 06520, USA; Graduate Program in Biochemistry, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, 90035, Brazil.
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Russo D, Ancillotto L, Jones G. Bats are still not birds in the digital era: echolocation call variation and why it matters for bat species identification. CAN J ZOOL 2018. [DOI: 10.1139/cjz-2017-0089] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The recording and analysis of echolocation calls are fundamental methods used to study bat distribution, ecology, and behavior. However, the goal of identifying bats in flight from their echolocation calls is not always possible. Unlike bird songs, bat calls show large variation that often makes identification challenging. The problem has not been fully overcome by modern digital-based hardware and software for bat call recording and analysis. Besides providing fundamental insights into bat physiology, ecology, and behavior, a better understanding of call variation is therefore crucial to best recognize limits and perspectives of call classification. We provide a comprehensive overview of sources of interspecific and intraspecific echolocation call variations, illustrating its adaptive significance and highlighting gaps in knowledge. We remark that further research is needed to better comprehend call variation and control for it more effectively in sound analysis. Despite the state-of-art technology in this field, combining acoustic surveys with capture and roost search, as well as limiting identification to species with distinctive calls, still represent the safest way of conducting bat surveys.
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Affiliation(s)
- Danilo Russo
- Wildlife Research Unit, Dipartimento di Agraria, Università degli Studi di Napoli Federico II, 80055 Portici, Italy
- School of Biological Sciences, University of Bristol, Bristol BS8 1TQ, United Kingdom
| | - Leonardo Ancillotto
- Wildlife Research Unit, Dipartimento di Agraria, Università degli Studi di Napoli Federico II, 80055 Portici, Italy
| | - Gareth Jones
- School of Biological Sciences, University of Bristol, Bristol BS8 1TQ, United Kingdom
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Hulgard K, Ratcliffe JM. Sonar sound groups and increased terminal buzz duration reflect task complexity in hunting bats. Sci Rep 2016; 6:21500. [PMID: 26857019 PMCID: PMC4746672 DOI: 10.1038/srep21500] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Accepted: 01/25/2016] [Indexed: 11/21/2022] Open
Abstract
More difficult tasks are generally regarded as such because they demand greater attention. Echolocators provide rare insight into this relationship because biosonar signals can be monitored. Here we show that bats produce longer terminal buzzes and more sonar sound groups during their approach to prey under presumably more difficult conditions. Specifically, we found Daubenton’s bats, Myotis daubentonii, produced longer buzzes when aerial-hawking versus water-trawling prey, but that bats taking revolving air- and water-borne prey produced more sonar sound groups than did the bats when taking stationary prey. Buzz duration and sonar sound groups have been suggested to be independent means by which bats attend to would-be targets and other objects of interest. We suggest that for attacking bats both should be considered as indicators of task difficulty and that the buzz is, essentially, an extended sonar sound group.
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Affiliation(s)
- Katrine Hulgard
- Department of Biology, University of Southern Denmark, 5230 Odense, Denmark
| | - John M Ratcliffe
- Department of Biology, University of Southern Denmark, 5230 Odense, Denmark.,Department of Biology, University of Toronto Mississauga, ON L5L 1C6, Canada
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To Scream or to Listen? Prey Detection and Discrimination in Animal-Eating Bats. BAT BIOACOUSTICS 2016. [DOI: 10.1007/978-1-4939-3527-7_4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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