1
|
O’Connell-Rodwell CE, Berezin JL, Dharmarajan A, Ravicz ME, Hu Y, Guan X, O’Connor KN, Puria S. The impact of size on middle-ear sound transmission in elephants, the largest terrestrial mammal. PLoS One 2024; 19:e0298535. [PMID: 38598472 PMCID: PMC11006165 DOI: 10.1371/journal.pone.0298535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Accepted: 01/25/2024] [Indexed: 04/12/2024] Open
Abstract
Elephants have a unique auditory system that is larger than any other terrestrial mammal. To quantify the impact of larger middle ear (ME) structures, we measured 3D ossicular motion and ME sound transmission in cadaveric temporal bones from both African and Asian elephants in response to air-conducted (AC) tonal pressure stimuli presented in the ear canal (PEC). Results were compared to similar measurements in humans. Velocities of the umbo (VU) and stapes (VST) were measured using a 3D laser Doppler vibrometer in the 7-13,000 Hz frequency range, stapes velocity serving as a measure of energy entering the cochlea-a proxy for hearing sensitivity. Below the elephant ME resonance frequency of about 300 Hz, the magnitude of VU/PEC was an order of magnitude greater than in human, and the magnitude of VST/PEC was 5x greater. Phase of VST/PEC above ME resonance indicated that the group delay in elephant was approximately double that of human, which may be related to the unexpectedly high magnitudes at high frequencies. A boost in sound transmission across the incus long process and stapes near 9 kHz was also observed. We discuss factors that contribute to differences in sound transmission between these two large mammals.
Collapse
Affiliation(s)
- Caitlin E. O’Connell-Rodwell
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Otolaryngology, Head & Neck Surgery, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Jodie L. Berezin
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Anbuselvan Dharmarajan
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Michael E. Ravicz
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Otolaryngology, Head & Neck Surgery, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Yihan Hu
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Xiying Guan
- School of Medicine, Wayne State University, Detroit, Michigan, United States of America
| | - Kevin N. O’Connor
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Sunil Puria
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Otolaryngology, Head & Neck Surgery, Harvard Medical School, Boston, Massachusetts, United States of America
- Graduate Program in Speech and Hearing and Biosciences and Technologies, Harvard Medical School, Boston, Massachusetts, United States of America
| |
Collapse
|
2
|
Beeck VC, Heilmann G, Kerscher M, Stoeger AS. Sound Visualization Demonstrates Velopharyngeal Coupling and Complex Spectral Variability in Asian Elephants. Animals (Basel) 2022; 12:2119. [PMID: 36009709 PMCID: PMC9404934 DOI: 10.3390/ani12162119] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 08/02/2022] [Accepted: 08/13/2022] [Indexed: 12/05/2022] Open
Abstract
Sound production mechanisms set the parameter space available for transmitting biologically relevant information in vocal signals. Low-frequency rumbles play a crucial role in coordinating social interactions in elephants' complex fission-fusion societies. By emitting rumbles through either the oral or the three-times longer nasal vocal tract, African elephants alter their spectral shape significantly. In this study, we used an acoustic camera to visualize the sound emission of rumbles in Asian elephants, which have received far less research attention than African elephants. We recorded nine adult captive females and analyzed the spectral parameters of 203 calls, including vocal tract resonances (formants). We found that the majority of rumbles (64%) were nasally emitted, 21% orally, and 13% simultaneously through the mouth and trunk, demonstrating velopharyngeal coupling. Some of the rumbles were combined with orally emitted roars. The nasal rumbles concentrated most spectral energy in lower frequencies exhibiting two formants, whereas the oral and mixed rumbles contained higher formants, higher spectral energy concentrations and were louder. The roars were the loudest, highest and broadest in frequency. This study is the first to demonstrate velopharyngeal coupling in a non-human animal. Our findings provide a foundation for future research into the adaptive functions of the elephant acoustic variability for information coding, localizability or sound transmission, as well as vocal flexibility across species.
Collapse
Affiliation(s)
- Veronika C. Beeck
- Department of Behavioural and Cognitive Biology, University of Vienna, 1030 Vienna, Austria
| | | | | | - Angela S. Stoeger
- Department of Behavioural and Cognitive Biology, University of Vienna, 1030 Vienna, Austria
| |
Collapse
|
3
|
Li LL, He R, Pansini R, Quan RC. Prolonged proximity to humans ensures better performance of semi-captive Asian elephants at discriminating between human individuals by voice. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.963052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
To avoid risks, organisms must recognize threatening heterospecies from non-threatening ones via acoustic cues from a distance. With land-use change, humans have encroached considerably into natural areas. Therefore, it is beneficial to animals to use acoustic cues to discriminate between different levels of threats posed by humans. Our study aims at testing this discriminatory ability in Asian elephants (Elephas maximus), animals that have been for long history subjected to human interaction. We tested whether eighteen semi-captive elephants could discriminate between voices of their own mahouts (i.e., who take care of the elephants exclusively) and of other mahouts (unfamiliar individuals). The results showed that elephants responded successfully to the commands from their own mahouts, with an average response rate as high as 78.8%. The more years the mahouts had been as their caretakers, the more the elephant showed active responses toward the commands. Female elephants responded to the commands more frequently and faster than males. Also younger elephants responded more frequently and faster than older elephants. We argue that Asian elephants can discriminate between familiar and unfamiliar humans by acoustic cues alone. Proximity with humans may be a factor, as fundamental as domestication, for animals to develop heterospecies discriminatory ability.
Collapse
|
4
|
Pokharel SS, Sharma N, Sukumar R. Viewing the rare through public lenses: insights into dead calf carrying and other thanatological responses in Asian elephants using YouTube videos. ROYAL SOCIETY OPEN SCIENCE 2022; 9:211740. [PMID: 35620003 PMCID: PMC9114935 DOI: 10.1098/rsos.211740] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Accepted: 04/19/2022] [Indexed: 05/03/2023]
Abstract
Documenting the behavioural repertoire of an animal species is important for understanding that species' natural history. Many behaviours such as mating, parturition and death may be observed only rarely in the wild due to the low frequency of occurrence, short duration and the species' elusiveness. Opportunistic documentation of rare behaviours is therefore valuable for deciphering the behavioural complexity in a species. In this context, digital platforms may serve as useful data sources for studying rare behaviours in animals. Using videos uploaded on YouTube, we document and construct a tentative repertoire of thanatological responses (death-related behaviours) in Asian elephants (Elephas maximus). The most frequently observed thanatological responses included postural changes, guarding/keeping vigil, touching, investigating the carcass, epimeletic behaviours and vocalizations. We also describe some infrequently observed behaviours, including carrying dead calves by adult females, re-assurance-like behaviours and attempts to support dying or dead conspecifics, some of which were only known anecdotally in Asian elephants. Our observations indicate the significance of open-source video data on digital platforms for gaining insights into rarely observed behaviours and support the accumulating evidence for higher cognitive abilities of Asian elephants in the context of comparative thanatology.
Collapse
Affiliation(s)
| | - Nachiketha Sharma
- Centre for Ecological Sciences, Indian Institute of Science, Bengaluru, India
| | - Raman Sukumar
- Centre for Ecological Sciences, Indian Institute of Science, Bengaluru, India
| |
Collapse
|
5
|
Acknowledging the Relevance of Elephant Sensory Perception to Human–Elephant Conflict Mitigation. Animals (Basel) 2022; 12:ani12081018. [PMID: 35454264 PMCID: PMC9031250 DOI: 10.3390/ani12081018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2022] [Revised: 04/11/2022] [Accepted: 04/12/2022] [Indexed: 02/05/2023] Open
Abstract
Simple Summary Elephants have a unique sensory perspective of the world, using their complex olfactory and auditory systems to make foraging and social decisions. All three species of elephants are endangered and inhabit environments, which are being affected rapidly by human development. Anthropogenic disturbances can have significant effects on elephants’ abilities to perceive sensory information and communicate with one another, potentially further endangering their survival. Conflicts over high-quality resources also arise from the overlapping habitation of humans and elephants. While many different methods have been employed to reduce this conflict, we propose that elephants’ unique olfactory and acoustic sensory strengths be considered in future mitigation strategies to achieve coexistence. Abstract Elephants are well known for their socio-cognitive abilities and capacity for multi-modal sensory perception and communication. Their highly developed olfactory and acoustic senses provide them with a unique non-visual perspective of their physical and social worlds. The use of these complex sensory signals is important not only for communication between conspecifics, but also for decisions about foraging and navigation. These decisions have grown increasingly risky given the exponential increase in unpredictable anthropogenic change in elephants’ natural habitats. Risk taking often develops from the overlap of human and elephant habitat in Asian and African range countries, where elephants forage for food in human habitat and crop fields, leading to conflict over high-quality resources. To mitigate this conflict, a better understanding of the elephants’ sensory world and its impact on their decision-making process should be considered seriously in the development of long-term strategies for promoting coexistence between humans and elephants. In this review, we explore the elephants’ sensory systems for audition and olfaction, their multi-modal capacities for communication, and the anthropogenic changes that are affecting their behavior, as well as the need for greater consideration of elephant behavior in elephant conservation efforts.
Collapse
|
6
|
Fuchs E, Beeck VC, Baotic A, Stoeger AS. Acoustic structure and information content of trumpets in female Asian elephants (Elephas maximus). PLoS One 2021; 16:e0260284. [PMID: 34813615 PMCID: PMC8610244 DOI: 10.1371/journal.pone.0260284] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2021] [Accepted: 11/05/2021] [Indexed: 12/02/2022] Open
Abstract
Most studies on elephant vocal communication have focused on the low-frequency rumble, with less effort on other vocalization types such as the most characteristic elephant call, the trumpet. Yet, a better and more complete understanding of the elephant vocal system requires investigating other vocalization types and their functioning in more detail as well. We recorded adult female Asian elephants (Elephas maximus) at a private facility in Nepal and analyzed 206 trumpets from six individuals regarding their frequency, temporal and contour shape, and related acoustic parameters of the fundamental frequency. We also tested for information content regarding individuality and context. Finally, we recorded the occurrence of non-linear phenomena such as bifurcation, biphonation, subharmonics and deterministic chaos. We documented a mean fundamental frequency ± SD of 474 ± 70 Hz and a mean duration ± SD of 1.38 ± 1.46 s (Nindiv. = 6, Ncalls = 206). Our study reveals that the contour of the fundamental frequency of trumpets encodes information about individuality, but we found no evidence for trumpet subtypes in greeting versus disturbance contexts. Non-linear phenomena prevailed and varied in abundance among individuals, suggesting that irregularities in trumpets might enhance the potential for individual recognition. We propose that trumpets in adult female Asian elephants serve to convey an individual's identity as well as to signal arousal and excitement to conspecifics.
Collapse
Affiliation(s)
- Evelyn Fuchs
- Mammal Communication Lab, Department of Behavioral and Cognitive Biology, University of Vienna, Vienna, Austria
| | - Veronika C. Beeck
- Mammal Communication Lab, Department of Behavioral and Cognitive Biology, University of Vienna, Vienna, Austria
| | - Anton Baotic
- Mammal Communication Lab, Department of Behavioral and Cognitive Biology, University of Vienna, Vienna, Austria
| | - Angela S. Stoeger
- Mammal Communication Lab, Department of Behavioral and Cognitive Biology, University of Vienna, Vienna, Austria
| |
Collapse
|
7
|
Stoeger AS, Baotic A, Heilmann G. Vocal Creativity in Elephant Sound Production. BIOLOGY 2021; 10:750. [PMID: 34439982 PMCID: PMC8389636 DOI: 10.3390/biology10080750] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Revised: 08/01/2021] [Accepted: 08/02/2021] [Indexed: 11/16/2022]
Abstract
How do elephants achieve their enormous vocal flexibility when communicating, imitating or creating idiosyncratic sounds? The mechanisms that underpin this trait combine motoric abilities with vocal learning processes. We demonstrate the unusual production techniques used by five African savanna elephants to create idiosyncratic sounds, which they learn to produce on cue by positive reinforcement training. The elephants generate these sounds by applying nasal tissue vibration via an ingressive airflow at the trunk tip, or by contracting defined superficial muscles at the trunk base. While the production mechanisms of the individuals performing the same sound categories are similar, they do vary in fine-tuning, revealing that each individual has its own specific sound-producing strategy. This plasticity reflects the creative and cognitive abilities associated with 'vocal' learning processes. The fact that these sounds were reinforced and cue-stimulated suggests that social feedback and positive reinforcement can facilitate vocal creativity and vocal learning behavior in elephants. Revealing the mechanism and the capacity for vocal learning and sound creativity is fundamental to understanding the eloquence within the elephants' communication system. This also helps to understand the evolution of human language and of open-ended vocal systems, which build upon similar cognitive processes.
Collapse
Affiliation(s)
- Angela S. Stoeger
- Mammal Communication Lab, Department of Behavioral and Cognitive Biology, University of Vienna, 1030 Vienna, Austria;
| | - Anton Baotic
- Mammal Communication Lab, Department of Behavioral and Cognitive Biology, University of Vienna, 1030 Vienna, Austria;
| | | |
Collapse
|
8
|
Beeck VC, Heilmann G, Kerscher M, Stoeger AS. A novel theory of Asian elephant high-frequency squeak production. BMC Biol 2021; 19:121. [PMID: 34134675 PMCID: PMC8210382 DOI: 10.1186/s12915-021-01026-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 04/14/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Anatomical and cognitive adaptations to overcome morpho-mechanical limitations of laryngeal sound production, where body size and the related vocal apparatus dimensions determine the fundamental frequency, increase vocal diversity across taxa. Elephants flexibly use laryngeal and trunk-based vocalizations to form a repertoire ranging from infrasonic rumbles to higher-pitched trumpets. Moreover, they are among the few evolutionarily distantly related animals (humans, pinnipeds, cetaceans, birds) capable of imitating species-atypical sounds. Yet, their vocal plasticity has so far not been related to functions within their natural communicative system, in part because not all call types have been systematically studied. Here, we reveal how Asian elephants (Elephas maximus) produce species-specific squeaks (F0 300-2300 Hz) by using acoustic camera recordings to visualize sound emission and examining this alongside acoustic, behavioral, and morphological data across seven captive groups. RESULTS We found that squeaks were emitted through the closed mouth in synchrony with cheek depression and retraction of the labial angles. The simultaneous emission of squeaks with nasal snorts (biphonation) in one individual confirmed that squeak production was independent of nasal passage involvement and this implicated oral sound production. The squeaks' spectral structure is incongruent with laryngeal sound production and aerodynamic whistles, pointing to tissue vibration as the sound source. Anatomical considerations suggest that the longitudinal closed lips function as the vibrators. Acoustic and temporal parameters exhibit high intra- and inter-individual variability that enables individual but no call-subtype classification. Only 19 of 56 study subjects were recorded to squeak, mostly during alarming contexts and social arousal but some also on command. CONCLUSION Our results strongly suggest that Asian elephants force air from the small oral cavity through the tensed lips, inducing self-sustained lip vibration. Besides human brass players, lip buzzing is not described elsewhere in the animal kingdom. Given the complexity of the proposed mechanism, the surprising absence of squeaking in most of the unrelated subjects and the indication for volitional control, we hypothesize that squeak production involves social learning. Our study offers new insights into how vocal and cognitive flexibility enables mammals to overcome size-related limitations of laryngeal sound production. This flexibility enables Asian elephants to exploit a frequency range spanning seven octaves within their communicative system.
Collapse
Affiliation(s)
- Veronika C Beeck
- Department of Behavioural and Cognitive Biology, Mammal Communication Lab, University of Vienna, Vienna, Austria.
| | | | | | - Angela S Stoeger
- Department of Behavioural and Cognitive Biology, Mammal Communication Lab, University of Vienna, Vienna, Austria.
| |
Collapse
|
9
|
Marasinghe MSLRP, Nilanthi RMR, Hathurusinghe HABM, Sooriyabandara MGC, Chandrasekara CHWMRB, Jayawardana KANC, Kodagoda MM, Rajapakse RC, Bandaranayake PCG. Revisiting traditional SSR based methodologies available for elephant genetic studies. Sci Rep 2021; 11:8718. [PMID: 33888797 PMCID: PMC8062488 DOI: 10.1038/s41598-021-88034-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Accepted: 03/30/2021] [Indexed: 02/02/2023] Open
Abstract
Asian elephant (Elephas maximus) plays a significant role in natural ecosystems and it is considered as an endangered animal. Molecular genetics studies on elephants' dates back to 1990s. Microsatellite markers have been the preferred choice and have played a major role in ecological, evolutionary and conservation research on elephants over the past 20 years. However, technical constraints especially related to the specificity of traditionally developed microsatellite markers have brought to question their application, specifically when degraded samples are utilized for analysis. Therefore, we analyzed the specificity of 24 sets of microsatellite markers frequently used for elephant molecular work. Comparative wet lab analysis was done with blood and dung DNA in parallel with in silico work. Our data suggest cross-amplification of unspecific products when field-collected dung samples are utilized in assays. The necessity of Asian elephant specific set of microsatellites and or better molecular techniques are highlighted.
Collapse
Affiliation(s)
- M S L R P Marasinghe
- Department of Wildlife Conservation, 811/A, Jayanthipura Road, Battaramulla, 10120, Sri Lanka
| | - R M R Nilanthi
- Department of Wildlife Conservation, 811/A, Jayanthipura Road, Battaramulla, 10120, Sri Lanka
| | - H A B M Hathurusinghe
- Agricultural Biotechnology Centre, Faculty of Agriculture, University of Peradeniya, Peradeniya, 20400, Sri Lanka
| | - M G C Sooriyabandara
- Department of Wildlife Conservation, 811/A, Jayanthipura Road, Battaramulla, 10120, Sri Lanka
| | - C H W M R B Chandrasekara
- Agricultural Biotechnology Centre, Faculty of Agriculture, University of Peradeniya, Peradeniya, 20400, Sri Lanka
| | - K A N C Jayawardana
- Department of Wildlife Conservation, 811/A, Jayanthipura Road, Battaramulla, 10120, Sri Lanka
| | - M M Kodagoda
- Agricultural Biotechnology Centre, Faculty of Agriculture, University of Peradeniya, Peradeniya, 20400, Sri Lanka
| | - R C Rajapakse
- Department of National Zoological Gardens, Anagarika Dharmapala Mawatha, Dehiwala, 10350, Sri Lanka
| | - P C G Bandaranayake
- Agricultural Biotechnology Centre, Faculty of Agriculture, University of Peradeniya, Peradeniya, 20400, Sri Lanka.
| |
Collapse
|
10
|
Linn SN, Schmidt S, Scheumann M. Individual distinctiveness across call types of the southern white rhinoceros ( Ceratotherium simum simum). J Mammal 2021; 102:440-456. [PMID: 34121952 PMCID: PMC8189687 DOI: 10.1093/jmammal/gyab007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Accepted: 01/21/2021] [Indexed: 01/04/2023] Open
Abstract
Individual distinctiveness in the acoustic structure of vocalizations provides a basis for individual recognition in mammals and plays an important role in social behavior. Within a species, call types can differ in individual distinctiveness, which can be explained by three factors, namely differences in the social function, the distance of the caller to the receiver, and the acoustic structure of the call. We explored the variation in individual distinctiveness across three call types (Grunt, Hiss, Snort) of the southern white rhinoceros (Ceratotherium simum simum) and investigated to what extent the abovementioned factors account for individual distinctiveness. Calls were recorded from 25 adult southern white rhinoceroses in six different zoos. We used three methods to compare the level of individual distinctiveness across call types, namely discriminant function analysis (DFA), potential for individual identity coding (PIC), and the information criterion (Hs). The three call types possessed an acoustic structure capable of showing individual variation to different extents. Individual distinctiveness was lowest for Snorts, intermediate for Hisses, and highest for Grunts. The level of individual distinctiveness of all three call types was lower than that previously reported for Pant calls of this species. Calls functioning to mediate intragroup social interactions had the highest individual distinctiveness. This highlights that a given communicative function and the need for individual discrimination during a social interaction have a major influence on the degree of individual distinctiveness.
Collapse
Affiliation(s)
| | - Sabine Schmidt
- Institute of Zoology, University of Veterinary Medicine Hannover, Bünteweg 17, D-30559 Hannover, Germany
| | - Marina Scheumann
- Institute of Zoology, University of Veterinary Medicine Hannover, Bünteweg 17, D-30559 Hannover, Germany
| |
Collapse
|
11
|
|
12
|
Behavioural responses of free-ranging Asian elephants (Elephas maximus) towards dying and dead conspecifics. Primates 2019; 61:129-138. [DOI: 10.1007/s10329-019-00739-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Accepted: 07/31/2019] [Indexed: 10/26/2022]
|
13
|
Pardo MA, Poole JH, Stoeger AS, Wrege PH, O’Connell-Rodwell CE, Padmalal UK, de Silva S. Differences in combinatorial calls among the 3 elephant species cannot be explained by phylogeny. Behav Ecol 2019. [DOI: 10.1093/beheco/arz018] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Michael A Pardo
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY, USA
| | | | - Angela S Stoeger
- Mammal Communication Lab, Department of Cognitive Biology, University of Vienna, Vienna, Austria
| | - Peter H Wrege
- Elephant Listening Project, Cornell Lab of Ornithology, Ithaca, NY, USA
| | - Caitlin E O’Connell-Rodwell
- Department of Otolargyngology, Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA, USA
| | | | - Shermin de Silva
- Division of Biological Sciences, UC San Diego, Ecology Behavior and Evolution Section, CA, USA
| |
Collapse
|
14
|
Affiliation(s)
- Saki Yasui
- Kyoto City Zoo, Okazaki Koen, Okazaki Houshojicho, Sakyo-Ku, Kyoto City, Kyoto 606-8333, Japan
| | - Gen’ichi Idani
- Wildlife Research Centre, Kyoto University, 2-24 Tanaka-Sekiden-cho, Sakyo-Ku, Kyoto 606-8203, Japan
| |
Collapse
|
15
|
Wijayagunawardane MPB, Short RV, Samarakone TS, Nishany KBM, Harrington H, Perera BVP, Rassool R, Bittner EP. The use of audio playback to deter crop-raiding Asian elephants. WILDLIFE SOC B 2016. [DOI: 10.1002/wsb.652] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Missaka P. B. Wijayagunawardane
- Department of Animal Science; University of Peradeniya; Peradeniya 20400 Sri Lanka
- Department of Zoology; University of Melbourne; Parkville VIC 3010 Australia
| | - Roger V. Short
- Department of Zoology; University of Melbourne; Parkville VIC 3010 Australia
| | | | | | - Helena Harrington
- Department of Zoology; University of Melbourne; Parkville VIC 3010 Australia
| | - B. V. P. Perera
- Elephant Transit Home; Department of Wildlife Conservation; Udewalawe Sri Lanka
| | - Roger Rassool
- School of Physics; University of Melbourne; Parkville VIC 3010 Australia
| | - Evan P. Bittner
- Faculty of Veterinary and Agricultural Sciences; University of Melbourne; Parkville VIC 3010 Australia
| |
Collapse
|
16
|
Dunlop RA. Changes in vocal parameters with social context in humpback whales: considering the effect of bystanders. Behav Ecol Sociobiol 2016; 70:857-870. [PMID: 27217614 PMCID: PMC4859862 DOI: 10.1007/s00265-016-2108-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Revised: 03/20/2016] [Accepted: 03/21/2016] [Indexed: 11/29/2022]
Abstract
Abstract Many theories and communication models developed from terrestrial studies focus on a simple dyadic exchange between a sender and receiver. During social interactions, the “frequency code” hypothesis suggests that frequency characteristics of vocal signals can simultaneously encode for static signaler attributes (size or sex) and dynamic information, such as motivation or emotional state. However, the additional presence of a bystander may result in a change of signaling behavior if the costs and benefits associated with the presence of this bystander are different from that of a simple dyad. In this study, two common humpback whale social calls (“wops” and “grumbles”) were tested for differences related to group social behavior and the presence of bystanders. “Wop” parameters were stable with group social behavior, but were emitted at lower (14 dB) levels in the presence of a nearby singing whale compared to when a singing whale was not in the area. “Grumbles” were emitted at lower (30–39 Hz) fundamental frequencies in affiliative compared to non-affiliative groups and, in the presence of a nearby singing whale, were also emitted at lower (14 dB) levels. Vocal rates did not significantly change. The results suggest that, in humpbacks, the frequency in certain sound types relates to the social behavior of the vocalizing group, implying a frequency code system. The presence of a nearby audible bystander (a singing whale) had no effect on this frequency code, but by reducing their acoustic level, the signal-to-noise ratio at the singer would have been below 0, making it difficult for the singer to audibly detect the group. Significance statement The frequency, duration, and amplitude parameters of humpback whale social vocalizations were tested between different social contexts: group social behavior (affiliating versus non-affiliating), the presence of a nearby singing whale, and the presence of a nearby non-singing group. “Grumbles” (commonly heard low-frequency unmodulated sounds) frequencies were lower in affiliating groups compared to non-affiliating groups, suggesting a change in group motivation (such as levels of aggression). “Wop” (another common sound type) structure (frequency and duration) was similar in affiliating and non-affiliating groups. In the presence of an audible bystander (a singing whale), both sound types were emitted at similar rates, but much lower amplitudes (14 dB), vastly reducing the detectability of these sounds by the singer. This suggests that these groups were acoustically avoiding the singing whale. They did not, however, acoustically respond to the presence of a nearby non-singing group.
Collapse
Affiliation(s)
- Rebecca A Dunlop
- Cetacean Ecology and Acoustics Laboratory, School of Veterinary Science, The University of Queensland, Gatton, Queensland 4343 Australia
| |
Collapse
|
17
|
Eskelinen HC, Winship KA, Jones BL, Ames AEM, Kuczaj SA. Acoustic behavior associated with cooperative task success in bottlenose dolphins (Tursiops truncatus). Anim Cogn 2016; 19:789-97. [PMID: 27022973 DOI: 10.1007/s10071-016-0978-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Revised: 03/10/2016] [Accepted: 03/18/2016] [Indexed: 01/06/2023]
Abstract
Although many species have proven capable of cooperating to achieve common goals, the role of communication in cooperation has received relatively little attention. Analysis of communication between partners is vital in determining whether actions are truly cooperative rather than serendipitous or learned via trial and error (Chalmeau and Gallo in Behav Process 35:101-111, 1996a. doi: 10.1016/0376-6357(95)00049-6 , Primates 37:39-47, 1996b. doi: 10.1007/BF02382918 ). Wild cetaceans often produce sounds during cooperative foraging, playing, and mating, but the role of these sounds in cooperative events is largely unknown. Here, we investigated acoustic communication between two male bottlenose dolphins while they cooperatively opened a container (Kuczaj et al. in Anim Cogn 18:543-550, 2015b. doi: 10.1007/s10071-014-0822-4 ). Analyses of whistles, burst pulses, and bi-phonations that occurred during four contexts (i.e., no container, no animals interacting with container, one animal interacting with container, and two animals interacting with container) revealed that overall sound production rate significantly increased during container interactions. Sound production rates were also significantly higher during cooperative successes than solo successes, suggesting that the coordination of efforts rather than the apparatus itself was responsible for the phonation increase. The most common sound type during cooperative successes was burst pulse signals, similar to past recordings of cooperative events in bottlenose dolphins (Bastian in Animal sonar systems. Laboratoire de Physiologie Acoustique, Jouy-en Josas, pp 803-873, 1967; Connor and Smolker 1996).
Collapse
Affiliation(s)
| | - Kelley A Winship
- Dolphins Plus, Inc., 31 Corinne Pl, Key Largo, FL, 33037, USA
- University of Southern Mississippi, 118 College Drive #5025, Hattiesburg, MS, 39406, USA
| | - Brittany L Jones
- Dolphins Plus, Inc., 31 Corinne Pl, Key Largo, FL, 33037, USA
- University of Southern Mississippi, 118 College Drive #5025, Hattiesburg, MS, 39406, USA
| | - Audra E M Ames
- University of Southern Mississippi, 118 College Drive #5025, Hattiesburg, MS, 39406, USA
| | - Stan A Kuczaj
- University of Southern Mississippi, 118 College Drive #5025, Hattiesburg, MS, 39406, USA
| |
Collapse
|
18
|
Garcia M, Gingras B, Bowling DL, Herbst CT, Boeckle M, Locatelli Y, Fitch WT. Structural Classification of Wild Boar ( Sus scrofa) Vocalizations. Ethology 2016; 122:329-342. [PMID: 27065507 PMCID: PMC4793927 DOI: 10.1111/eth.12472] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Revised: 07/20/2015] [Accepted: 12/28/2015] [Indexed: 11/28/2022]
Abstract
Determining whether a species' vocal communication system is graded or discrete requires definition of its vocal repertoire. In this context, research on domestic pig (Sus scrofa domesticus) vocalizations, for example, has led to significant advances in our understanding of communicative functions. Despite their close relation to domestic pigs, little is known about wild boar (Sus scrofa) vocalizations. The few existing studies, conducted in the 1970s, relied on visual inspections of spectrograms to quantify acoustic parameters and lacked statistical analysis. Here, we use objective signal processing techniques and advanced statistical approaches to classify 616 calls recorded from semi‐free ranging animals. Based on four spectral and temporal acoustic parameters—quartile Q25, duration, spectral flux, and spectral flatness—extracted from a multivariate analysis, we refine and extend the conclusions drawn from previous work and present a statistically validated classification of the wild boar vocal repertoire into four call types: grunts, grunt‐squeals, squeals, and trumpets. While the majority of calls could be sorted into these categories using objective criteria, we also found evidence supporting a graded interpretation of some wild boar vocalizations as acoustically continuous, with the extremes representing discrete call types. The use of objective criteria based on modern techniques and statistics in respect to acoustic continuity advances our understanding of vocal variation. Integrating our findings with recent studies on domestic pig vocal behavior and emotions, we emphasize the importance of grunt‐squeals for acoustic approaches to animal welfare and underline the need of further research investigating the role of domestication on animal vocal communication.
Collapse
Affiliation(s)
- Maxime Garcia
- Department of Cognitive Biology University of Vienna Vienna Austria
| | - Bruno Gingras
- Department of Cognitive Biology University of Vienna Vienna Austria
| | - Daniel L Bowling
- Department of Cognitive Biology University of Vienna Vienna Austria
| | - Christian T Herbst
- Voice Research Lab Department of Biophysics Faculty of Science Palacký University Olomouc Czech Republic
| | - Markus Boeckle
- Department of Cognitive Biology University of Vienna Vienna Austria; Department of Psychotherapy and Biopsychosocial Health Danube University Krems Krems Austria
| | - Yann Locatelli
- Réserve de la Haute Touche Muséum National d'Histoire Naturelle Obterre France; Equipe Interactions Cellulaires et Fertilité UMR0085 Physiologie de la Reproduction et des Comportements Institut National de la Recherche Agronomique Nouzilly France
| | - W Tecumseh Fitch
- Department of Cognitive Biology University of Vienna Vienna Austria
| |
Collapse
|
19
|
Comparative sequence analyses of genome and transcriptome reveal novel transcripts and variants in the Asian elephant Elephas maximus. J Biosci 2015; 40:891-907. [DOI: 10.1007/s12038-015-9580-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
20
|
Zeppelzauer M, Stoeger AS. Establishing the fundamentals for an elephant early warning and monitoring system. BMC Res Notes 2015; 8:409. [PMID: 26338528 PMCID: PMC4558827 DOI: 10.1186/s13104-015-1370-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Accepted: 08/18/2015] [Indexed: 11/25/2022] Open
Abstract
Background The decline of habitat for elephants due to expanding human activity is a serious conservation problem. This has continuously escalated the human–elephant conflict in Africa and Asia. Elephants make extensive use of powerful infrasonic calls (rumbles) that travel distances of up to several kilometers. This makes elephants well-suited for acoustic monitoring because it enables detecting elephants even if they are out of sight. In sight, their distinct visual appearance makes them a good candidate for visual monitoring. We provide an integrated overview of our interdisciplinary project that established the scientific fundamentals for a future early warning and monitoring system for humans who regularly experience serious conflict with elephants. We first draw the big picture of an early warning and monitoring system, then review the developed solutions for automatic acoustic and visual detection, discuss specific challenges and present open future work necessary to build a robust and reliable early warning and monitoring system that is able to operate in situ. Findings We present a method for the automated detection of elephant rumbles that is robust to the diverse noise sources present in situ. We evaluated the method on an extensive set of audio data recorded under natural field conditions. Results show that the proposed method outperforms existing approaches and accurately detects elephant rumbles. Our visual detection method shows that tracking elephants in wildlife videos (of different sizes and postures) is feasible and particularly robust at near distances. Discussion From our project results we draw a number of conclusions that are discussed and summarized. We clearly identified the most critical challenges and necessary improvements of the proposed detection methods and conclude that our findings have the potential to form the basis for a future automated early warning system for elephants. We discuss challenges that need to be solved and summarize open topics in the context of a future early warning and monitoring system. We conclude that a long-term evaluation of the presented methods in situ using real-time prototypes is the most important next step to transfer the developed methods into practical implementation.
Collapse
Affiliation(s)
- Matthias Zeppelzauer
- Media Computing Group, St. Pölten University of Applied Sciences, Matthias-Corvinus Strasse 15, 3100, St. Pölten, Austria.
| | - Angela S Stoeger
- Department of Cognitive Biology, University of Vienna, Althanstrasse 14, 1090, Vienna, Austria.
| |
Collapse
|
21
|
Chaverri G, Gillam EH. Repeatability in the contact calling system of Spix's disc-winged bat (Thyroptera tricolor). ROYAL SOCIETY OPEN SCIENCE 2015; 2:140197. [PMID: 26064578 PMCID: PMC4448792 DOI: 10.1098/rsos.140197] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Accepted: 12/22/2014] [Indexed: 06/04/2023]
Abstract
Spix's disc-winged bat (Thyroptera tricolor) forms cohesive groups despite using an extremely ephemeral roost, partly due to the use of two acoustic signals that help individuals locate roost sites and group members. While the calls that aid in group cohesion are commonly used, some bats rarely or never produce them. Here, we examine whether the differences observed in the contact calling behaviour of T. tricolor are repeatable; that is, whether individual differences are consistent. We recorded contact calls of individuals in the field and rates and patterns of vocalization. To determine whether measured variables were consistent within individuals, we estimated repeatability (R), which compares within-individual to among-individual variance in behavioural traits. Our results show that repeatability for call variables was moderate but significant, and that repeatability was highest for the average number of calls produced (R=0.46-0.49). Our results demonstrate important individual differences in the contact calling behaviour of T. tricolor; we discuss how these could be the result of mechanisms such as frequency-dependent selection that favour groups composed of individuals with diverse vocal strategies. Future work should address whether changes in social environment, specifically group membership and social status, affect vocal behaviour.
Collapse
Affiliation(s)
| | - Erin H. Gillam
- Department of Biological Sciences, North Dakota State University, Fargo, ND 58108, USA
| |
Collapse
|
22
|
Stoeger AS, Manger P. Vocal learning in elephants: neural bases and adaptive context. Curr Opin Neurobiol 2014; 28:101-7. [PMID: 25062469 PMCID: PMC4181794 DOI: 10.1016/j.conb.2014.07.001] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Revised: 06/28/2014] [Accepted: 07/01/2014] [Indexed: 10/28/2022]
Abstract
In the last decade clear evidence has accumulated that elephants are capable of vocal production learning. Examples of vocal imitation are documented in African (Loxodonta africana) and Asian (Elephas maximus) elephants, but little is known about the function of vocal learning within the natural communication systems of either species. We are also just starting to identify the neural basis of elephant vocalizations. The African elephant diencephalon and brainstem possess specializations related to aspects of neural information processing in the motor system (affecting the timing and learning of trunk movements) and the auditory and vocalization system. Comparative interdisciplinary (from behavioral to neuroanatomical) studies are strongly warranted to increase our understanding of both vocal learning and vocal behavior in elephants.
Collapse
Affiliation(s)
- Angela S Stoeger
- Department of Cognitive Biology, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria.
| | - Paul Manger
- School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| |
Collapse
|
23
|
English M, Kaplan G, Rogers LJ. Is painting by elephants in zoos as enriching as we are led to believe? PeerJ 2014; 2:e471. [PMID: 25071994 PMCID: PMC4103097 DOI: 10.7717/peerj.471] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Accepted: 06/16/2014] [Indexed: 11/25/2022] Open
Abstract
The relationship between the activity of painting and performance of stereotyped and other stress-related behaviour was investigated in four captive Asian elephants at Melbourne Zoo, Australia. The activity involved the elephant being instructed to paint on a canvas by its keeper in front of an audience. Painting by elephants in zoos is commonly believed to be a form of enrichment, but this assumption had not been based on any systematic research. If an activity is enriching we would expect stress-related behaviour to be reduced but we found no evidence of the elephants anticipating the painting activity and no effect on the performance of stereotyped or other stress-related behaviour either before or after the painting session. This indicates that the activity does not fulfil one of the main aims of enrichment. However, if an elephant was not selected to paint on a given day this was associated with higher levels of non-interactive behaviour, a possible indicator of stress. Behavioural observations associated with ear, eye and trunk positions during the painting session showed that the elephant’s attentiveness to the painting activity or to the keeper giving instruction varied between individuals. Apart from positive reinforcement from the keeper, the results indicated that elephants gain little enrichment from the activity of painting. Hence, the benefits of this activity appear to be limited to the aesthetic appeal of these paintings to the people viewing them.
Collapse
Affiliation(s)
- Megan English
- Centre for Neuroscience and Animal Behaviour, School of Science and Technology, University of New England , Armidale, NSW , Australia ; Centre for Biodiversity and Restoration Ecology, School of Biological Sciences, Victoria University of Wellington , New Zealand
| | - Gisela Kaplan
- Centre for Neuroscience and Animal Behaviour, School of Science and Technology, University of New England , Armidale, NSW , Australia
| | - Lesley J Rogers
- Centre for Neuroscience and Animal Behaviour, School of Science and Technology, University of New England , Armidale, NSW , Australia
| |
Collapse
|
24
|
Plotnik JM, de Waal FB. Asian elephants (Elephas maximus) reassure others in distress. PeerJ 2014; 2:e278. [PMID: 24688856 PMCID: PMC3932735 DOI: 10.7717/peerj.278] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2013] [Accepted: 01/29/2014] [Indexed: 11/28/2022] Open
Abstract
Contact directed by uninvolved bystanders toward others in distress, often termed consolation, is uncommon in the animal kingdom, thus far only demonstrated in the great apes, canines, and corvids. Whereas the typical agonistic context of such contact is relatively rare within natural elephant families, other causes of distress may trigger similar, other-regarding responses. In a study carried out at an elephant camp in Thailand, we found that elephants affiliated significantly more with other individuals through directed, physical contact and vocal communication following a distress event than in control periods. In addition, bystanders affiliated with each other, and matched the behavior and emotional state of the first distressed individual, suggesting emotional contagion. The initial distress responses were overwhelmingly directed toward ambiguous stimuli, thus making it difficult to determine if bystanders reacted to the distressed individual or showed a delayed response to the same stimulus. Nonetheless, the directionality of the contacts and their nature strongly suggest attention toward the emotional states of conspecifics. The elephants' behavior is therefore best classified with similar consolation responses by apes, possibly based on convergent evolution of empathic capacities.
Collapse
Affiliation(s)
- Joshua M. Plotnik
- Living Links, Yerkes National Primate Research Center and Department of Psychology, Emory University, Atlanta, GA, USA
| | - Frans B.M. de Waal
- Living Links, Yerkes National Primate Research Center and Department of Psychology, Emory University, Atlanta, GA, USA
| |
Collapse
|
25
|
Thuppil V, Coss RG. Wild Asian elephants distinguish aggressive tiger and leopard growls according to perceived danger. Biol Lett 2013; 9:20130518. [PMID: 24026347 DOI: 10.1098/rsbl.2013.0518] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Prey species exhibit antipredator behaviours such as alertness, aggression and flight, among others, in response to predators. The nature of this response is variable, with animals reacting more strongly in situations of increased vulnerability. Our research described here is the first formal study to investigate night-time antipredator behaviour in any species of elephants, Asian or African. We examined the provocative effects of elephant-triggered tiger and leopard growls while elephants attempted to crop-raid. Tigers opportunistically prey on elephant calves, whereas leopards pose no threat; therefore, we predicted that the elephant response would be reflective of this difference. Elephants reacted similarly cautiously to the simulated presence of felids of both species by eventually moving away, but differed markedly in their more immediate behavioural responses. Elephants retreated silently to tiger-growl playbacks, whereas they responded with aggressive vocalizations, such as trumpets and grunts, to leopard-growl playbacks. Elephants also lingered in the area and displayed alert or investigative behaviours in response to leopard growls when compared with tiger growls. We anticipate that the methods outlined here will promote further study of elephant antipredator behaviour in a naturalistic context, with applications for conservation efforts as well.
Collapse
Affiliation(s)
- Vivek Thuppil
- Animal Behavior Graduate Group, University of California, Davis, CA, USA.
| | | |
Collapse
|
26
|
Stoeger AS, Mietchen D, Oh S, de Silva S, Herbst CT, Kwon S, Fitch WT. An Asian elephant imitates human speech. Curr Biol 2012; 22:2144-8. [PMID: 23122846 PMCID: PMC3548412 DOI: 10.1016/j.cub.2012.09.022] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Revised: 08/13/2012] [Accepted: 09/12/2012] [Indexed: 11/05/2022]
Abstract
Vocal imitation has convergently evolved in many species, allowing learning and cultural transmission of complex, conspecific sounds, as in birdsong [1, 2]. Scattered instances also exist of vocal imitation across species, including mockingbirds imitating other species or parrots and mynahs producing human speech [3, 4]. Here, we document a male Asian elephant (Elephas maximus) that imitates human speech, matching Korean formants and fundamental frequency in such detail that Korean native speakers can readily understand and transcribe the imitations. To create these very accurate imitations of speech formant frequencies, this elephant (named Koshik) places his trunk inside his mouth, modulating the shape of the vocal tract during controlled phonation. This represents a wholly novel method of vocal production and formant control in this or any other species. One hypothesized role for vocal imitation is to facilitate vocal recognition by heightening the similarity between related or socially affiliated individuals [1, 2]. The social circumstances under which Koshik’s speech imitations developed suggest that one function of vocal learning might be to cement social bonds and, in unusual cases, social bonds across species.
Collapse
Affiliation(s)
- Angela S Stoeger
- Department of Cognitive Biology, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria.
| | | | | | | | | | | | | |
Collapse
|
27
|
Herler A, Stoeger AS. Vocalizations and associated behaviour of Asian elephant (Elephas maximus) calves. BEHAVIOUR 2012. [DOI: 10.1163/156853912x648516] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
|
28
|
Elephants know when they need a helping trunk in a cooperative task. Proc Natl Acad Sci U S A 2011; 108:5116-21. [PMID: 21383191 DOI: 10.1073/pnas.1101765108] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Elephants are widely assumed to be among the most cognitively advanced animals, even though systematic evidence is lacking. This void in knowledge is mainly due to the danger and difficulty of submitting the largest land animal to behavioral experiments. In an attempt to change this situation, a classical 1930s cooperation paradigm commonly tested on monkeys and apes was modified by using a procedure originally designed for chimpanzees (Pan troglodytes) to measure the reactions of Asian elephants (Elephas maximus). This paradigm explores the cognition underlying coordination toward a shared goal. What do animals know or learn about the benefits of cooperation? Can they learn critical elements of a partner's role in cooperation? Whereas observations in nature suggest such understanding in nonhuman primates, experimental results have been mixed, and little evidence exists with regards to nonprimates. Here, we show that elephants can learn to coordinate with a partner in a task requiring two individuals to simultaneously pull two ends of the same rope to obtain a reward. Not only did the elephants act together, they inhibited the pulling response for up to 45 s if the arrival of a partner was delayed. They also grasped that there was no point to pulling if the partner lacked access to the rope. Such results have been interpreted as demonstrating an understanding of cooperation. Through convergent evolution, elephants may have reached a cooperative skill level on a par with that of chimpanzees.
Collapse
|