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Salmi R, Jones CE, Carrigan J. Who is there? Captive western gorillas distinguish human voices based on familiarity and nature of previous interactions. Anim Cogn 2022; 25:217-228. [PMID: 34390429 DOI: 10.1007/s10071-021-01543-y/figures/4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 06/28/2021] [Accepted: 07/31/2021] [Indexed: 05/26/2023]
Abstract
The ability to recognize conspecifics by their acoustic signals is of crucial importance to social animals, especially where visibility is limited, because it allows for discrimination between familiar and unfamiliar individuals and facilitates associations with and the avoidance of particular conspecifics. Animals may also benefit from an ability to recognize and use the information coded into the auditory signals of other species. Companion species such as dogs, cats, and horses are able to discriminate between familiar and unfamiliar human voices; however, whether this ability is widespread across vertebrates is still unknown. Using playback experiments, we tested whether western gorillas living at Zoo Atlanta were able to discriminate between the voices of subgroups of people: i.e., unfamiliar individuals, familiar individuals with whom the gorillas had positive interactions, and familiar individuals with whom they had negative interactions. Gorillas responded significantly more often (longer gazing duration, higher gazing frequency, shorter latency, and larger number of distress behaviors) to the voices of unfamiliar and familiar-negative individuals than to those of familiar-positive individuals, indicating that they recognized the voices of subgroup of people based on familiarity and possibly the nature of the relationship with them. Future studies should determine whether this is also the case in the wild, where interspecific associations with humans are less intense than they are in captive settings.
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Affiliation(s)
- Roberta Salmi
- Department of Anthropology, University of Georgia, Athens, GA, 30602, USA.
- Department of Geography, Center for Geospatial Research, University of Georgia, Athens, GA, USA.
| | - Caroline E Jones
- Department of Psychology, University of Georgia, Athens, GA, USA
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2
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Melchor J, Vergara J, Figueroa T, Morán I, Lemus L. Formant-Based Recognition of Words and Other Naturalistic Sounds in Rhesus Monkeys. Front Neurosci 2021; 15:728686. [PMID: 34776842 PMCID: PMC8586527 DOI: 10.3389/fnins.2021.728686] [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: 06/21/2021] [Accepted: 10/08/2021] [Indexed: 11/21/2022] Open
Abstract
In social animals, identifying sounds is critical for communication. In humans, the acoustic parameters involved in speech recognition, such as the formant frequencies derived from the resonance of the supralaryngeal vocal tract, have been well documented. However, how formants contribute to recognizing learned sounds in non-human primates remains unclear. To determine this, we trained two rhesus monkeys to discriminate target and non-target sounds presented in sequences of 1–3 sounds. After training, we performed three experiments: (1) We tested the monkeys’ accuracy and reaction times during the discrimination of various acoustic categories; (2) their ability to discriminate morphing sounds; and (3) their ability to identify sounds consisting of formant 1 (F1), formant 2 (F2), or F1 and F2 (F1F2) pass filters. Our results indicate that macaques can learn diverse sounds and discriminate from morphs and formants F1 and F2, suggesting that information from few acoustic parameters suffice for recognizing complex sounds. We anticipate that future neurophysiological experiments in this paradigm may help elucidate how formants contribute to the recognition of sounds.
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Affiliation(s)
- Jonathan Melchor
- Department of Cognitive Neuroscience, Institute of Cell Physiology, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - José Vergara
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, United States
| | - Tonatiuh Figueroa
- Department of Cognitive Neuroscience, Institute of Cell Physiology, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Isaac Morán
- Department of Cognitive Neuroscience, Institute of Cell Physiology, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Luis Lemus
- Department of Cognitive Neuroscience, Institute of Cell Physiology, Universidad Nacional Autónoma de México, Mexico City, Mexico
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3
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Who is there? Captive western gorillas distinguish human voices based on familiarity and nature of previous interactions. Anim Cogn 2021; 25:217-228. [PMID: 34390429 DOI: 10.1007/s10071-021-01543-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 06/28/2021] [Accepted: 07/31/2021] [Indexed: 10/20/2022]
Abstract
The ability to recognize conspecifics by their acoustic signals is of crucial importance to social animals, especially where visibility is limited, because it allows for discrimination between familiar and unfamiliar individuals and facilitates associations with and the avoidance of particular conspecifics. Animals may also benefit from an ability to recognize and use the information coded into the auditory signals of other species. Companion species such as dogs, cats, and horses are able to discriminate between familiar and unfamiliar human voices; however, whether this ability is widespread across vertebrates is still unknown. Using playback experiments, we tested whether western gorillas living at Zoo Atlanta were able to discriminate between the voices of subgroups of people: i.e., unfamiliar individuals, familiar individuals with whom the gorillas had positive interactions, and familiar individuals with whom they had negative interactions. Gorillas responded significantly more often (longer gazing duration, higher gazing frequency, shorter latency, and larger number of distress behaviors) to the voices of unfamiliar and familiar-negative individuals than to those of familiar-positive individuals, indicating that they recognized the voices of subgroup of people based on familiarity and possibly the nature of the relationship with them. Future studies should determine whether this is also the case in the wild, where interspecific associations with humans are less intense than they are in captive settings.
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4
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Rendall D. Aping Language: Historical Perspectives on the Quest for Semantics, Syntax, and Other Rarefied Properties of Human Language in the Communication of Primates and Other Animals. Front Psychol 2021; 12:675172. [PMID: 34366994 PMCID: PMC8345011 DOI: 10.3389/fpsyg.2021.675172] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Accepted: 06/21/2021] [Indexed: 11/13/2022] Open
Abstract
In 1980, Robert Seyfarth, Dorothy Cheney and Peter Marler published a landmark paper in Science claiming language-like semantic communication in the alarm calls of vervet monkeys. This article and the career research program it spawned for its authors catalyzed countless other studies searching for semantics, and then also syntax and other rarefied properties of language, in the communication systems of non-human primates and other animals. It also helped bolster a parallel tradition of teaching symbolism and syntax in artificial language systems to great apes. Although the search for language rudiments in the communications of primates long predates the vervet alarm call story, it is difficult to overstate the impact of the vervet research, for it fueled field and laboratory research programs for several generations of primatologists and kept busy an equal number of philosophers, linguists, and cognitive scientists debating possible implications for the origins and evolution of language and other vaunted elements of the human condition. Now 40-years on, the original vervet alarm call findings have been revised and claims of semanticity recanted; while other evidence for semantics and syntax in the natural communications of non-humans is sparse and weak. Ultimately, we are forced to conclude that there are simply few substantive precedents in the natural communications of animals for the high-level informational and representational properties of language, nor its complex syntax. This conclusion does not mean primates cannot be taught some version of these elements of language in artificial language systems - in fact, they can. Nor does it mean there is no continuity between the natural communications of animals and humans that could inform the evolution of language - in fact, there is such continuity. It just does not lie in the specialized semantic and syntactic properties of language. In reviewing these matters, I consider why it is that primates do not evince high-level properties of language in their natural communications but why we so readily accepted that they did or should; and what lessons we might draw from that experience. In the process, I also consider why accounts of human-like characteristics in animals can be so irresistibly appealing.
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Affiliation(s)
- Drew Rendall
- Department of Biology, University of New Brunswick, Fredericton, NB, Canada
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Chakrabarti S, Bump JK, Jhala YV, Packer C. Contrasting levels of social distancing between the sexes in lions. iScience 2021; 24:102406. [PMID: 34013168 PMCID: PMC8113998 DOI: 10.1016/j.isci.2021.102406] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 03/29/2021] [Accepted: 04/06/2021] [Indexed: 11/08/2022] Open
Abstract
Understanding sexual segregation is crucial to comprehend sociality. A comparative analysis of long-term lion data from Serengeti and Ngorongoro in Tanzania, and Gir in India, reveals that male-female associations are contingent upon male and female group size, prey-size and availability, and the number of prides that each male coalition currently resides. Males maintain proximity with females, whereas females are responsible for segregation except at large kills. Lions feed on the largest prey in Ngorongoro and the smallest in Gir, and females spend the most time with males in Ngorongoro and the least in Gir. Females roar less often in prey-scarce circumstances in Serengeti and throughout the year in Gir possibly to prevent being tracked by males that parasitize on female kills. However, females readily associate with males when available prey is large and abundant. Contrasting availability of resources between Gir and Serengeti/Ngorongoro helps explain the varying degrees of sexual segregation and appears to drive differences in mating systems between these lion populations. Sexual segregation in lion populations is driven by resource availability Females are responsible for segregating from males, except at large kills When prey is scarce, females reduce detection by males by roaring less frequently Contrasting proximity between the sexes has led to variation in mating strategies in these populations of African and Asian lions
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Affiliation(s)
- Stotra Chakrabarti
- Department of Fisheries, Wildlife and Conservation Biology, University of Minnesota, 150 Skok Hall, 2003 Buford Circle, St. Paul, MN 55108, USA.,Department of Animal Ecology and Conservation Biology, Wildlife Institute of India, Chandrabani, Dehra Dun, Uttarakhand 248001, India
| | - Joseph K Bump
- Department of Fisheries, Wildlife and Conservation Biology, University of Minnesota, 150 Skok Hall, 2003 Buford Circle, St. Paul, MN 55108, USA
| | - Yadvendradev V Jhala
- Department of Animal Ecology and Conservation Biology, Wildlife Institute of India, Chandrabani, Dehra Dun, Uttarakhand 248001, India
| | - Craig Packer
- Department of Ecology, Evolution and Behavior, University of Minnesota, St. Paul, MN 55108, USA
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Jenikejew J, Chaignon B, Linn S, Scheumann M. Proximity-based vocal networks reveal social relationships in the Southern white rhinoceros. Sci Rep 2020; 10:15104. [PMID: 32934303 PMCID: PMC7492360 DOI: 10.1038/s41598-020-72052-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 08/24/2020] [Indexed: 11/17/2022] Open
Abstract
Vocal communication networks can be linked to social behaviour, allowing a deeper understanding of social relationships among individuals. For this purpose, the description of vocal dyads is fundamental. In group-living species, this identification is based on behavioural indicators which require a high level of reactivity during social interactions. In the present study, we alternatively established a proximity-based approach to investigate whether sex-specific differences in vocal communication reflect social behaviour in a species with rather loose social associations and low levels of reactivity: the Southern white rhinoceros (Ceratotherium simum simum). We performed audio- and video recordings of 30 captive animals from seven groups. Vocal networks for the four most common call types were constructed by considering conspecifics at close distance (≤ 1 body length) to the sender as potential receivers. The analysis of the resulting unidirectional structures showed that not only the sex of the sender but also the sex of the potential receiver, the quality of social interactions (affiliative or agonistic) as well as association strength predict the intensity of vocal interactions between group members. Thus, a proximity-based approach can be used to construct vocal networks providing information about the social relationships of conspecifics-even in species with loose social associations where behavioural indicators are limited.
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Affiliation(s)
- Julia Jenikejew
- Institute of Zoology, University of Veterinary Medicine Hannover, Bünteweg 17, 30559, Hannover, Germany.
| | | | | | - Marina Scheumann
- Institute of Zoology, University of Veterinary Medicine Hannover, Bünteweg 17, 30559, Hannover, Germany
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Shen D, Fang K, Fan Y, Shen J, Yang J, Cui J, Tang Y, Fang G. Sex differences in vocalization are reflected by event-related potential components in the music frog. Anim Cogn 2020; 23:477-490. [PMID: 32016618 DOI: 10.1007/s10071-020-01350-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2018] [Revised: 01/02/2020] [Accepted: 01/17/2020] [Indexed: 11/28/2022]
Abstract
Sex differences in vocalization have been commonly found in vocal animals. It remains unclear, however, how animals perceive and discriminate these differences. The amplitudes and latencies of event-related potentials (ERP) components can reflect the auditory processing efficiency and time course. We investigated the neural mechanisms of auditory processing in the Emei music frog (Nidirana daunchina) using an Oddball paradigm with ERP. We recorded and analyzed eletroencephalogram (EEG) signals from the forebrain and midbrain when the subjects listened to white noise (WN) and conspecific sex-specific vocalizations. We found that (1) both amplitudes and latencies of some ERP components evoked by conspecific calls were significantly higher than those by WN, suggesting the music frogs can discriminate conspecific vocalizations from background noise; (2) both amplitudes and latencies of most ERP components evoked by female calls were significantly higher or longer than those by male calls, implying that the ERP components can reflect sex differences in vocalization; and (3) there were significant differences in ERP amplitudes between male and female subjects, suggesting a sexual dimorphism in auditory perception. Together, the present results indicate that the music frog could discriminate conspecific calls from noise, male's calls from female's ones, and sexual dimorphism of auditory perception existed in this species.
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Affiliation(s)
- Di Shen
- Chengdu Institute of Biology, Chinese Academy of Sciences, No. 9 Section 4, Renmin Nan Road, Chengdu, 610041, Sichuan, People's Republic of China.,University of Chinese Academy of Sciences, 19A Yuquan Road, Beijing, People's Republic of China
| | - Ke Fang
- Institute of Bio-Inspired Structure and Surface Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016, People's Republic of China
| | - Yanzhu Fan
- Chengdu Institute of Biology, Chinese Academy of Sciences, No. 9 Section 4, Renmin Nan Road, Chengdu, 610041, Sichuan, People's Republic of China.,University of Chinese Academy of Sciences, 19A Yuquan Road, Beijing, People's Republic of China
| | - Jiangyan Shen
- Chengdu Institute of Biology, Chinese Academy of Sciences, No. 9 Section 4, Renmin Nan Road, Chengdu, 610041, Sichuan, People's Republic of China.,University of Chinese Academy of Sciences, 19A Yuquan Road, Beijing, People's Republic of China
| | - Jing Yang
- Chengdu Institute of Biology, Chinese Academy of Sciences, No. 9 Section 4, Renmin Nan Road, Chengdu, 610041, Sichuan, People's Republic of China.,University of Chinese Academy of Sciences, 19A Yuquan Road, Beijing, People's Republic of China
| | - Jianguo Cui
- Chengdu Institute of Biology, Chinese Academy of Sciences, No. 9 Section 4, Renmin Nan Road, Chengdu, 610041, Sichuan, People's Republic of China
| | - Yezhong Tang
- Chengdu Institute of Biology, Chinese Academy of Sciences, No. 9 Section 4, Renmin Nan Road, Chengdu, 610041, Sichuan, People's Republic of China
| | - Guangzhan Fang
- Chengdu Institute of Biology, Chinese Academy of Sciences, No. 9 Section 4, Renmin Nan Road, Chengdu, 610041, Sichuan, People's Republic of China.
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9
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Boë LJ, Sawallis TR, Fagot J, Badin P, Barbier G, Captier G, Ménard L, Heim JL, Schwartz JL. Which way to the dawn of speech?: Reanalyzing half a century of debates and data in light of speech science. SCIENCE ADVANCES 2019; 5:eaaw3916. [PMID: 32076631 PMCID: PMC7000245 DOI: 10.1126/sciadv.aaw3916] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/16/2018] [Accepted: 10/10/2019] [Indexed: 06/10/2023]
Abstract
Recent articles on primate articulatory abilities are revolutionary regarding speech emergence, a crucial aspect of language evolution, by revealing a human-like system of proto-vowels in nonhuman primates and implicitly throughout our hominid ancestry. This article presents both a schematic history and the state of the art in primate vocalization research and its importance for speech emergence. Recent speech research advances allow more incisive comparison of phylogeny and ontogeny and also an illuminating reinterpretation of vintage primate vocalization data. This review produces three major findings. First, even among primates, laryngeal descent is not uniquely human. Second, laryngeal descent is not required to produce contrasting formant patterns in vocalizations. Third, living nonhuman primates produce vocalizations with contrasting formant patterns. Thus, evidence now overwhelmingly refutes the long-standing laryngeal descent theory, which pushes back "the dawn of speech" beyond ~200 ka ago to over ~20 Ma ago, a difference of two orders of magnitude.
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Affiliation(s)
- Louis-Jean Boë
- Université Grenoble Alpes, CNRS, Grenoble INP, Institute of Engineering Univ. Grenoble Alpes, GIPSA-lab, Grenoble, France
| | | | - Joël Fagot
- Brain and Language Research Institute, Aix-Marseille University, Aix-en-Provence, France
- Cognitive Psychology Laboratory, Centre National de la Recherche Scientifique and Aix-Marseille University, Marseille, France
| | - Pierre Badin
- Université Grenoble Alpes, CNRS, Grenoble INP, Institute of Engineering Univ. Grenoble Alpes, GIPSA-lab, Grenoble, France
| | - Guillaume Barbier
- Université Grenoble Alpes, CNRS, Grenoble INP, Institute of Engineering Univ. Grenoble Alpes, GIPSA-lab, Grenoble, France
- School of Speech Pathology and Audiology, Université de Montréal, Montréal, Québec, Canada
| | | | - Lucie Ménard
- Laboratoire de Phonétique, Université du Québec à Montréal, Montréal, Québec, Canada
- Center for Research on Brain, Language, and Music, Montréal, Québec, Canada
| | - Jean-Louis Heim
- Muséum National d'Histoire Naturelle, Paris, France
- Institut de Paléontologie Humaine, Paris, France
| | - Jean-Luc Schwartz
- Université Grenoble Alpes, CNRS, Grenoble INP, Institute of Engineering Univ. Grenoble Alpes, GIPSA-lab, Grenoble, France
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11
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Lima SGC, Sousa-Lima RS, Tokumaru RS, Nogueira-Filho SLG, Nogueira SSC. Vocal complexity and sociality in spotted paca (Cuniculus paca). PLoS One 2018; 13:e0190961. [PMID: 29364898 PMCID: PMC5783385 DOI: 10.1371/journal.pone.0190961] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Accepted: 12/22/2017] [Indexed: 11/19/2022] Open
Abstract
The evolution of sociality is related to many ecological factors that act on animals as selective forces, thus driving the formation of groups. Group size will depend on the payoffs of group living. The Social Complexity Hypothesis for Communication (SCHC) predicts that increases in group size will be related to increases in the complexity of the communication among individuals. This hypothesis, which was confirmed in some mammal societies, may be useful to trace sociality in the spotted paca (Cuniculus paca), a Neotropical caviomorph rodent reported as solitary. There are, however, sightings of groups in the wild, and farmers easily form groups of spotted paca in captivity. Thus, we aimed to describe the acoustic repertoire of captive spotted paca to test the SCHC and to obtain insights about the sociability of this species. Moreover, we aimed to verify the relationship between group size and acoustic repertoire size of caviomorph rodents, to better understand the evolution of sociality in this taxon. We predicted that spotted paca should display a complex acoustic repertoire, given their social behavior in captivity and group sightings in the wild. We also predicted that in caviomorph species the group size would increase with acoustic repertoire, supporting the SCHC. We performed a Linear Discriminant Analysis (LDA) based on acoustic parameters of the vocalizations recorded. In addition, we applied an independent contrasts approach to investigate sociality in spotted paca following the social complexity hypothesis, independent of phylogeny. Our analysis showed that the spotted paca's acoustic repertoire contains seven vocal types and one mechanical signal. The broad acoustic repertoire of the spotted paca might have evolved given the species' ability to live in groups. The relationship between group size and the size of the acoustic repertoires of caviomorph species was confirmed, providing additional support for the SCHC in yet another group of diverse mammals-caviomorph rodents.
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Affiliation(s)
- Stella G. C. Lima
- Laboratório de Bioacústica, Departamento de Fisiologia e Comportamento / Programa de Pós-Graduação em Psicobiologia, Universidade Federal do Rio Grande do Norte, Natal, RN, Brazil
| | - Renata S. Sousa-Lima
- Laboratório de Bioacústica, Departamento de Fisiologia e Comportamento / Programa de Pós-Graduação em Psicobiologia, Universidade Federal do Rio Grande do Norte, Natal, RN, Brazil
| | - Rosana S. Tokumaru
- Departamento de Psicologia Social e do Desenvolvimento, Universidade Federal do Espírito Santo, Vitória, ES, Brazil
| | - Sérgio L. G. Nogueira-Filho
- Laboratório de Etologia Aplicada, Departamento de Ciências Biológicas, Universidade Estadual de Santa Cruz, Ilhéus, BA, Brazil
| | - Selene S. C. Nogueira
- Laboratório de Etologia Aplicada, Departamento de Ciências Biológicas, Universidade Estadual de Santa Cruz, Ilhéus, BA, Brazil
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13
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Déaux EC, Clarke JA, Charrier I. Dingo Howls: The Content and Efficacy of a Long-Range Vocal Signal. Ethology 2016. [DOI: 10.1111/eth.12510] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Eloïse C. Déaux
- Department of Biological Sciences; Macquarie University; Sydney NSW Australia
| | - Jennifer A. Clarke
- Department of Biological Sciences; Macquarie University; Sydney NSW Australia
| | - Isabelle Charrier
- Institut des Neurosciences Paris-Saclay; UMR 9197; CNRS; Université Paris-Saclay, Université Paris-Sud; Orsay France
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Yin LY, Fei HL, Chen GS, Li JH, Cui LW, Fan PF. Effects of group density, hunting, and temperature on the singing patterns of eastern hoolock gibbons (Hoolock leuconedys) in Gaoligongshan, Southwest China. Am J Primatol 2016; 78:861-71. [PMID: 27167327 DOI: 10.1002/ajp.22553] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Revised: 04/09/2016] [Accepted: 04/09/2016] [Indexed: 01/04/2023]
Abstract
Many non-human primates produce species-specific loud calls to communicate within and between groups over long distances. Understanding these calling patterns can provide insights into how individuals modify their behavior in response to environmental variables as well as help to design efficient bioacoustic survey techniques. Eastern hoolock gibbons in Gaoligongshan inhabit the coldest habitat of all gibbon populations, but both conservation and research efforts on this population have been minimal. We studied singing patterns of two habituated and two unhabituated groups at two sites in Gaoligongshan between July 2010 and June 2015. We systematically collected data of their calls, and its relationship to temperature, group density, and hunting pressure over at least 1 year for each group. Our goal was to elucidate how these factors affect singing patterns of eastern hoolock gibbons. We found that adult pairs coordinated their singing to produce duet bouts that lasted for an average of 25.5 min. The singing rate (number of bouts/number on monitoring days*100%: 7.5-31.4%) was notably lower than other gibbon populations, presumably due to low group density (about 0.5 groups/km(2) ) and prevalence of hunting at the study site. Cold temperature also affected gibbons' singing behavior. Our study groups called, on average, 2.5 hr after sunrise, probably foraging first in the early morning after long nights in this cold habitat delayed singing. Furthermore, mean temperatures in the morning (8:00-12:00 am) were higher on singing days than on non-singing days, and one group called less frequently when monthly mean temperature was below 10°C. Our findings indicate that both hunting pressure from humans and low temperatures suppress calling behavior in hoolock gibbons. Such information is critical in evaluating the use of duetting as a monitoring technique for this endangered gibbon species. Am. J. Primatol. 78:861-871, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Long-Yun Yin
- Key Laboratory of Forest Disaster Warning and Control in Yunnan Province, Southwest Forestry University, Kunming, Yunnan, P.R. China
| | - Han-Lan Fei
- Institute of Eastern-Himalaya Biodiversity Research, Dali University, Yunnan, P.R. China
| | - Gui-Shou Chen
- Key Laboratory of Forest Disaster Warning and Control in Yunnan Province, Southwest Forestry University, Kunming, Yunnan, P.R. China
| | - Jia-Hua Li
- Gaoligongshan National Nature Reserve, Baoshan, Yunnan, P.R. China
| | - Liang-Wei Cui
- Key Laboratory of Forest Disaster Warning and Control in Yunnan Province, Southwest Forestry University, Kunming, Yunnan, P.R. China
| | - Peng-Fei Fan
- Institute of Eastern-Himalaya Biodiversity Research, Dali University, Yunnan, P.R. China.,School of Life Sciences, Sun Yat-sen University, Guangzhou, P.R. China
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15
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Volodin IA, Sibiryakova OV, Volodina EV. Sex and age-class differences in calls of Siberian wapiti Cervus elaphus sibiricus. Mamm Biol 2016. [DOI: 10.1016/j.mambio.2015.09.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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16
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Vocal Production by Terrestrial Mammals: Source, Filter, and Function. VERTEBRATE SOUND PRODUCTION AND ACOUSTIC COMMUNICATION 2016. [DOI: 10.1007/978-3-319-27721-9_8] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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17
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Cao D, Zhou H, Wei W, Lei M, Yuan S, Qi D, Zhang Z. Vocal repertoire of adult captive red pandas (Ailurus fulgens). ANIM BIOL 2016. [DOI: 10.1163/15707563-00002493] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Vocal signals are a common communication tool used to recognize different individuals, advertise fertile phases or discriminate amongst potential mates. Therefore, a thorough understanding of vocal repertoires forms the basis for investigating the role of acoustic signaling in the sexual and social behavior of any animal. Red pandas (Ailurus fulgens) are classified as a vulnerable species and have declined by as much as 40% over the past 50 years in China. Adult red pandas are known to call frequently during mating and aggressive encounters; however, no quantitative description of their vocalizations has been attempted. Here, the vocal repertoire of captive red pandas was investigated. Acoustical and statistical analyses indicated seven vocalization types during the breeding season: “growl”, “bark”, “squeal”, “bleat”, “hoot”, “grunt” and “twitter”; the spectrogram for each vocalization type was extracted. The type of vocalizations produced varied with behavioral state and implies different functional contexts. Future studies are needed to uncover the functions of red panda vocalizations in individual recognition, sexual selection and social interaction.
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Affiliation(s)
- Dandan Cao
- Giant Panda Conservation and Culture Research Center, China West Normal University, Shida Road 1#, Nanchong 637009, China
| | - Hong Zhou
- Giant Panda Conservation and Culture Research Center, China West Normal University, Shida Road 1#, Nanchong 637009, China
| | - Wei Wei
- Giant Panda Conservation and Culture Research Center, China West Normal University, Shida Road 1#, Nanchong 637009, China
| | - Miaowen Lei
- Giant Panda Conservation and Culture Research Center, China West Normal University, Shida Road 1#, Nanchong 637009, China
| | - Shibin Yuan
- Giant Panda Conservation and Culture Research Center, China West Normal University, Shida Road 1#, Nanchong 637009, China
| | - Dunwu Qi
- Chengdu Research Base of Giant Panda Breeding, Panda Road 1375#, Chengdu 610081, China
| | - Zejun Zhang
- Giant Panda Conservation and Culture Research Center, China West Normal University, Shida Road 1#, Nanchong 637009, China
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Charlton BD. The Acoustic Structure and Information Content of Female Koala Vocal Signals. PLoS One 2015; 10:e0138670. [PMID: 26465340 PMCID: PMC4605621 DOI: 10.1371/journal.pone.0138670] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2015] [Accepted: 09/02/2015] [Indexed: 11/28/2022] Open
Abstract
Determining the information content of animal vocalisations can give valuable insights into the potential functions of vocal signals. The source-filter theory of vocal production allows researchers to examine the information content of mammal vocalisations by linking variation in acoustic features with variation in relevant physical characteristics of the caller. Here I used a source-filter theory approach to classify female koala vocalisations into different call-types, and determine which acoustic features have the potential to convey important information about the caller to other conspecifics. A two-step cluster analysis classified female calls into bellows, snarls and tonal rejection calls. Additional results revealed that female koala vocalisations differed in their potential to provide information about a given caller’s phenotype that may be of importance to receivers. Female snarls did not contain reliable acoustic cues to the caller’s identity and age. In contrast, female bellows and tonal rejection calls were individually distinctive, and the tonal rejection calls of older female koalas had consistently lower mean, minimum and maximum fundamental frequency. In addition, female bellows were significantly shorter in duration and had higher fundamental frequency, formant frequencies, and formant frequency spacing than male bellows. These results indicate that female koala vocalisations have the potential to signal the caller’s identity, age and sex. I go on to discuss the anatomical basis for these findings, and consider the possible functional relevance of signalling this type of information in the koala’s natural habitat.
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Affiliation(s)
- Benjamin D. Charlton
- School of Biology and Environmental Science, University College Dublin (UCD), Belfield, Dublin, Ireland
- * E-mail:
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19
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Charlton BD, Keating JL, Rengui L, Huang Y, Swaisgood RR. The acoustic structure of male giant panda bleats varies according to intersexual context. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2015; 138:1305-1312. [PMID: 26428769 DOI: 10.1121/1.4928606] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Although the acoustic structure of mammal vocal signals often varies according to the social context of emission, relatively few mammal studies have examined acoustic variation during intersexual advertisement. In the current study male giant panda bleats were recorded during the breeding season in three behavioural contexts: vocalising alone, during vocal interactions with females outside of peak oestrus, and during vocal interactions with peak-oestrous females. Male bleats produced during vocal interactions with peak-oestrous females were longer in duration and had higher mean fundamental frequency than those produced when males were either involved in a vocal interaction with a female outside of peak oestrus or vocalising alone. In addition, males produced bleats with higher rates of fundamental frequency modulation when they were vocalising alone than when they were interacting with females. These results show that acoustic features of male giant panda bleats have the potential to signal the caller's motivational state, and suggest that males increase the rate of fundamental frequency modulation in bleats when they are alone to maximally broadcast their quality and promote close-range contact with receptive females during the breeding season.
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Affiliation(s)
- Benjamin D Charlton
- School of Biology and Environmental Science, University College Dublin (UCD), Belfield, Dublin 4, Ireland
| | - Jennifer L Keating
- Applied Animal Ecology, San Diego Zoo's Institute for Conservation Research, San Diego, California 92027-7000, USA
| | - Li Rengui
- China Research and Conservation Centre for the Giant Panda, Sichuan, People's Republic of China
| | - Yan Huang
- China Research and Conservation Centre for the Giant Panda, Sichuan, People's Republic of China
| | - Ronald R Swaisgood
- Applied Animal Ecology, San Diego Zoo's Institute for Conservation Research, San Diego, California 92027-7000, USA
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20
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Nadhurou B, Gamba M, Andriaholinirina N, Ouledi A, Giacoma C. The vocal communication of the mongoose lemur (Eulemur mongoz): phonation mechanisms, acoustic features and quantitative analysis. ETHOL ECOL EVOL 2015. [DOI: 10.1080/03949370.2015.1039069] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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21
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Fernández-Vargas M, Johnston RE. Ultrasonic vocalizations in golden hamsters (Mesocricetus auratus) reveal modest sex differences and nonlinear signals of sexual motivation. PLoS One 2015; 10:e0116789. [PMID: 25714096 PMCID: PMC4340904 DOI: 10.1371/journal.pone.0116789] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Accepted: 12/16/2014] [Indexed: 11/29/2022] Open
Abstract
Vocal signaling is one of many behaviors that animals perform during social interactions. Vocalizations produced by both sexes before mating can communicate sex, identity and condition of the caller. Adult golden hamsters produce ultrasonic vocalizations (USV) after intersexual contact. To determine whether these vocalizations are sexually dimorphic, we analyzed the vocal repertoire for sex differences in: 1) calling rates, 2) composition (structural complexity, call types and nonlinear phenomena) and 3) acoustic structure. In addition, we examined it for individual variation in the calls. The vocal repertoire was mainly composed of 1-note simple calls and at least half of them presented some degree of deterministic chaos. The prevalence of this nonlinear phenomenon was confirmed by low values of harmonic-to-noise ratio for most calls. We found modest sexual differences between repertoires. Males were more likely than females to produce tonal and less chaotic calls, as well as call types with frequency jumps. Multivariate analysis of the acoustic features of 1-note simple calls revealed significant sex differences in the second axis represented mostly by entropy and bandwidth parameters. Male calls showed lower entropy and inter-quartile bandwidth than female calls. Because the variation of acoustic structure within individuals was higher than among individuals, USV could not be reliably assigned to the correct individual. Interestingly, however, this high variability, augmented by the prevalence of chaos and frequency jumps, could be the result of increased vocal effort. Hamsters motivated to produce high calling rates also produced longer calls of broader bandwidth. Thus, the sex differences found could be the result of different sex preferences but also of a sex difference in calling motivation or condition. We suggest that variable and complex USV may have been selected to increase responsiveness of a potential mate by communicating sexual arousal and preventing habituation to the caller.
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Affiliation(s)
| | - Robert E. Johnston
- Department of Psychology, Cornell University, Ithaca, NY, United States of America
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22
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Salmi R, Hammerschmidt K, Doran-Sheehy DM. Individual distinctiveness in call types of wild western female gorillas. PLoS One 2014; 9:e101940. [PMID: 25029238 PMCID: PMC4100815 DOI: 10.1371/journal.pone.0101940] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Accepted: 06/12/2014] [Indexed: 11/28/2022] Open
Abstract
Individually distinct vocalizations play an important role in animal communication, allowing call recipients to respond differentially based on caller identity. However, which of the many calls in a species' repertoire should have more acoustic variability and be more recognizable is less apparent. One proposed hypothesis is that calls used over long distances should be more distinct because visual cues are not available to identify the caller. An alternative hypothesis proposes that close calls should be more recognizable because of their importance in social interactions. To examine which hypothesis garners more support, the acoustic variation and individual distinctiveness of eight call types of six wild western gorilla (Gorilla gorilla) females were investigated. Acoustic recordings of gorilla calls were collected at the Mondika Research Center (Republic of Congo). Acoustic variability was high in all gorilla calls. Similar high inter-individual variation and potential for identity coding (PIC) was found for all call types. Discriminant function analyses confirmed that all call types were individually distinct (although for call types with lowest sample size - hum, grumble and scream - this result cannot be generalized), suggesting that neither the distance at which communication occurs nor the call social function alone can explain the evolution of identity signaling in western gorilla communication.
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Affiliation(s)
- Roberta Salmi
- Department of Anthropology, University of Georgia, Athens, Georgia, United States of America
- Interdepartmental Doctoral Program in Anthropological Sciences, Stony Brook University, Stony Brook, New York, United States of America
| | - Kurt Hammerschmidt
- Cognitive Ethology Laboratory, German Primate Center, Göttingen, Germany
| | - Diane M. Doran-Sheehy
- Department of Anthropology, Stony Brook University, Stony Brook, New York, United States of America
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Garcia M, Charlton BD, Wyman MT, Fitch WT, Reby D. Do red deer stags (Cervus elaphus) use roar fundamental frequency (F0) to assess rivals? PLoS One 2013; 8:e83946. [PMID: 24386312 PMCID: PMC3875517 DOI: 10.1371/journal.pone.0083946] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Accepted: 11/08/2013] [Indexed: 11/25/2022] Open
Abstract
It is well established that in humans, male voices are disproportionately lower pitched than female voices, and recent studies suggest that this dimorphism in fundamental frequency (F0) results from both intrasexual (male competition) and intersexual (female mate choice) selection for lower pitched voices in men. However, comparative investigations indicate that sexual dimorphism in F0 is not universal in terrestrial mammals. In the highly polygynous and sexually dimorphic Scottish red deer Cervus elaphus scoticus, more successful males give sexually-selected calls (roars) with higher minimum F0s, suggesting that high, rather than low F0s advertise quality in this subspecies. While playback experiments demonstrated that oestrous females prefer higher pitched roars, the potential role of roar F0 in male competition remains untested. Here we examined the response of rutting red deer stags to playbacks of re-synthesized male roars with different median F0s. Our results show that stags’ responses (latencies and durations of attention, vocal and approach responses) were not affected by the F0 of the roar. This suggests that intrasexual selection is unlikely to strongly influence the evolution of roar F0 in Scottish red deer stags, and illustrates how the F0 of terrestrial mammal vocal sexual signals may be subject to different selection pressures across species. Further investigations on species characterized by different F0 profiles are needed to provide a comparative background for evolutionary interpretations of sex differences in mammalian vocalizations.
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Affiliation(s)
- Maxime Garcia
- Department of Cognitive Biology, University of Vienna, Vienna, Austria
| | | | - Megan T. Wyman
- School of Psychology, University of Sussex, Brighton, United Kingdom
| | - W. Tecumseh Fitch
- Department of Cognitive Biology, University of Vienna, Vienna, Austria
| | - David Reby
- School of Psychology, University of Sussex, Brighton, United Kingdom
- * E-mail:
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25
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Junger J, Pauly K, Bröhr S, Birkholz P, Neuschaefer-Rube C, Kohler C, Schneider F, Derntl B, Habel U. Sex matters: Neural correlates of voice gender perception. Neuroimage 2013; 79:275-87. [PMID: 23660030 DOI: 10.1016/j.neuroimage.2013.04.105] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Revised: 04/12/2013] [Accepted: 04/24/2013] [Indexed: 10/26/2022] Open
Abstract
The basis for different neural activations in response to male and female voices as well as the question, whether men and women perceive male and female voices differently, has not been thoroughly investigated. Therefore, the aim of the present study was to examine the behavioral and neural correlates of gender-related voice perception in healthy male and female volunteers. fMRI data were collected while 39 participants (19 female) were asked to indicate the gender of 240 voice stimuli. These stimuli included recordings of 3-syllable nouns as well as the same recordings pitch-shifted in 2, 4 and 6 semitone steps in the direction of the other gender. Data analysis revealed a) equal voice discrimination sensitivity in men and women but better performance in the categorization of opposite-sex stimuli at least in men, b) increased responses to increasing gender ambiguity in the mid cingulate cortex and bilateral inferior frontal gyri, and c) stronger activation in a fronto-temporal neural network in response to voices of the opposite sex. Our results indicate a gender specific processing for male and female voices on a behavioral and neuronal level. We suggest that our results reflect higher sensitivity probably due to the evolutionary relevance of voice perception in mate selection.
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Affiliation(s)
- Jessica Junger
- Department of Psychiatry, Medical School, RWTH Aachen University, Aachen, Germany
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26
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Wyman M, Mooring M, McCowan B, Penedo M, Reby D, Hart L. Acoustic cues to size and quality in the vocalizations of male North American bison, Bison bison. Anim Behav 2012. [DOI: 10.1016/j.anbehav.2012.08.037] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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27
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Miller CT, Wren Thomas A. Individual recognition during bouts of antiphonal calling in common marmosets. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2012; 198:337-46. [PMID: 22277952 PMCID: PMC3799814 DOI: 10.1007/s00359-012-0712-7] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2011] [Revised: 01/11/2012] [Accepted: 01/12/2012] [Indexed: 11/28/2022]
Abstract
Many vocalizations are encoded with a diversity of acoustic information about the signal producer. Amongst this information content are social categories related to the identity of the caller that are important for determining if and how a signal receiver may interact with that individual. Here, we employed a novel playback method in common marmosets (Callithrix jacchus) to test individual recognition during bouts of antiphonal calling. These experiments utilized custom, interactive playback software that effectively engaged subjects in antiphonal calling using vocalizations produced by a single individual and presented 'probe' vocalization stimuli representing a different individual at specific points within bouts of calling. The aim here was to test whether marmosets would recognize that the probe stimulus was a phee call produced by a different individual. Data indicated that marmosets were able to detect the change in caller identity; subjects produced significantly fewer antiphonal call responses to probe than control stimuli and, in some conditions, exhibited a shorter latency to produce the vocal response. These data suggest that marmosets recognize the identity of the individual during bouts of antiphonal calling. Furthermore, these results provide a methodological foundation for implementing the probe playback procedure to examine a broader range of social categorization during vocal interactions.
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Affiliation(s)
- Cory T Miller
- Cortical Systems and Behavior Laboratory, Department of Psychology, University of California, 9500 Gilman Dr. #0109, La Jolla, San Diego, CA 92093, USA.
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28
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Bouchet H, Blois-Heulin C, Lemasson A. Age- and sex-specific patterns of vocal behavior in De Brazza's monkeys (Cercopithecus neglectus). Am J Primatol 2011; 74:12-28. [PMID: 21932330 DOI: 10.1002/ajp.21002] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2011] [Revised: 08/02/2011] [Accepted: 08/11/2011] [Indexed: 11/11/2022]
Abstract
Although vocal production is strongly genetically determined in nonhuman primates, vocal usage is more likely to be influenced by experience. Nonetheless, sex differences in both production and usage can be found in the vocal repertoire of adults, but little attention has been paid to their ontogeny. Here, we provide the first comprehensive analysis of the vocal repertoire of De Brazza's monkeys (Cercopithecus neglectus), with particular attention to age- and sex-specific patterns. This species has special interest because it is the only monogamous species of guenons, but it nevertheless shares the strong sexual morphological and behavioral dimorphism seen in other guenons. A structurally based classification of calls recorded in 23 captive individuals has been cross-validated by an analysis of the associated contexts of emission. We identified sound units that could be uttered alone or concatenated to form 10 call types, including only three types shared by all age-sex-classes. Both age- and sex-discrepancy in terms of phonation could be explained by maturational changes and morphological dimorphism. In general, call production and usage parallel those seen in other guenons, suggesting that phylogeny and sexual dimorphism play important roles in vocal communication in this species. However, the boundary between adult male and female vocal repertoires appeared to be less strict than previously reported, suggesting that both sexes have the capacity to produce calls of the other sex but that social roles may constrain this expression. Similarly, age-specific vocal patterns would reflect respective social roles, and experience to some extent. Finally, calling rates would reflect age-/sex-specific degree of involvement in intragroup social networks. These findings highlight the relative importance of phylogeny, morphology, and social system on the shaping of individual repertoires in nonhuman primates.
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Affiliation(s)
- Hélène Bouchet
- Université de Rennes1 CNRS, Station Biologique, Paimpont, France.
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29
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Maciej P, Fischer J, Hammerschmidt K. Transmission characteristics of primate vocalizations: implications for acoustic analyses. PLoS One 2011; 6:e23015. [PMID: 21829682 PMCID: PMC3148239 DOI: 10.1371/journal.pone.0023015] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2011] [Accepted: 07/11/2011] [Indexed: 11/19/2022] Open
Abstract
Acoustic analyses have become a staple method in field studies of animal vocal communication, with nearly all investigations using computer-based approaches to extract specific features from sounds. Various algorithms can be used to extract acoustic variables that may then be related to variables such as individual identity, context or reproductive state. Habitat structure and recording conditions, however, have strong effects on the acoustic structure of sound signals. The purpose of this study was to identify which acoustic parameters reliably describe features of propagated sounds. We conducted broadcast experiments and examined the influence of habitat type, transmission height, and re-recording distance on the validity (deviation from the original sound) and reliability (variation within identical recording conditions) of acoustic features of different primate call types. Validity and reliability varied independently of each other in relation to habitat, transmission height, and re-recording distance, and depended strongly on the call type. The smallest deviations from the original sounds were obtained by a visually-controlled calculation of the fundamental frequency. Start- and end parameters of a sound were most susceptible to degradation in the environment. Because the recording conditions can have appreciable effects on acoustic parameters, it is advisable to validate the extraction method of acoustic variables from recordings over longer distances before using them in acoustic analyses.
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Affiliation(s)
- Peter Maciej
- Cognitive Ethology Laboratory, German Primate Center, Göttingen, Germany.
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Charlton BD, Reby D. Context-related acoustic variation in male fallow deer (Dama dama) groans. PLoS One 2011; 6:e21066. [PMID: 21695159 PMCID: PMC3113910 DOI: 10.1371/journal.pone.0021066] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2011] [Accepted: 05/19/2011] [Indexed: 11/30/2022] Open
Abstract
While social and behavioural contexts are known to affect the acoustic structure of vocal signals in several mammal species, few studies have investigated context-related acoustic variation during inter-sexual advertisement and/or intra-sexual competition. Here we recorded male fallow deer groans during the breeding season and investigated how key acoustic parameters (fundamental frequency and formant frequencies) vary as a function of the social context in which they are produced. We found that in the presence of females, male fallow deer produced groans with higher mean fundamental frequency when vocal males were also present than they did when no vocal males were in close vicinity. We attribute this to the increased arousal state typically associated with this context. In addition, groan minimum formant frequency spacing was slightly, but significantly lower (indicating marginally more extended vocal tracts) when males were alone than when potential mates and/or competitors were nearby. This indicates that, contrary to our predictions, male fallow deer do not exaggerate the acoustic impression of their body size by further lowering their formant frequencies in the presence of potential mating partners and competitors. Furthermore, since the magnitude of the variation in groan minimum formant frequency spacing remains small compared to documented inter-individual differences, our findings are consistent with the hypothesis that formants are reliable static cues to body size during intra- and inter-sexual advertisement that do not concurrently encode dynamic motivation-related information.
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Affiliation(s)
| | - David Reby
- School of Psychology, University of Sussex, Sussex, United Kingdom
- * E-mail:
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31
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Meise K, Keller C, Cowlishaw G, Fischer J. Sources of acoustic variation: implications for production specificity and call categorization in chacma baboon (Papio ursinus) grunts. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2011; 129:1631-41. [PMID: 21428526 DOI: 10.1121/1.3531944] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Elucidating the information content of vocal signals is fundamental to the understanding of animal communication. Acoustically distinct calls produced in specific contexts allow listeners to predict future events and choose adequate responses. However, the vocal repertoires of most terrestrial mammals consist of a limited number of call types that vary within and between categories. These "graded signaling systems" are thought to be rich in information, at the cost of increasing uncertainty regarding call categorization. In this study, patterns of acoustic variation in grunts of wild chacma baboons (Papio ursinus) were assessed in relation to different contexts, callers' arousal, the presence of listeners, and individual identity. Although overall production specificity was low, and sensitive to the number of contexts under consideration, grunts given in three contexts could be statistically distinguished from each other. Contextual differences remained when controlling for caller arousal, suggesting that these differences cannot be explained by variation in arousal. No audience effect was detected, but individual identity was found to have an influence on acoustic structure. Overall, these results support the view that, in comparison to other signaling systems associated with hazardous conditions, lower production specificity might evolve under relaxed circumstances where unambiguous signaling is less important.
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Affiliation(s)
- Kristine Meise
- Department of Behavioral Biology, University of Bielefeld, Morgenbreede 45, 33615 Bielefeld, Germany.
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32
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Miller CT, Mandel K, Wang X. The communicative content of the common marmoset phee call during antiphonal calling. Am J Primatol 2010; 72:974-80. [PMID: 20549761 PMCID: PMC3715969 DOI: 10.1002/ajp.20854] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Vocalizations are a dominant means of communication for numerous species, including nonhuman primates. These acoustic signals are encoded with a rich array of information available to signal receivers that can be used to guide species-typical behaviors. In this study, we examined the communicative content of common marmoset phee calls, the species-typical long distance contact call, during antiphonal calling. This call type has a relatively stereotyped acoustic structure, consisting of a series of long tonal pulses. Analyses revealed that calls could be reliably classified based on the individual identity and social group of the caller. Our analyses did not, however, correctly classify phee calls recorded under different social contexts, although differences were evident along individual acoustic parameters. Further tests of antiphonal calling interactions showed that spontaneously produced phee calls differ from antiphonal phee calls in their peak and end frequency, which may be functionally significant. Overall, this study shows that the marmoset phee call has a rich communicative content encoded in its acoustic structure available to conspecifics during antiphonal calling exchanges.
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Affiliation(s)
- Cory T Miller
- Department of Psychology, University of California, San Diego, 92093, USA.
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33
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Charlton BD, Zhihe Z, Snyder RJ. Giant pandas perceive and attend to formant frequency variation in male bleats. Anim Behav 2010. [DOI: 10.1016/j.anbehav.2010.02.018] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Pozzi L, Gamba M, Giacoma C. The use of Artificial Neural Networks to classify primate vocalizations: A pilot study on black lemurs. Am J Primatol 2010; 72:337-48. [PMID: 20034021 DOI: 10.1002/ajp.20786] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The identification of the vocal repertoire of a species represents a crucial prerequisite for a correct interpretation of animal behavior. Artificial Neural Networks (ANNs) have been widely used in behavioral sciences, and today are considered a valuable classification tool for reducing the level of subjectivity and allowing replicable results across different studies. However, to date, no studies have applied this tool to nonhuman primate vocalizations. Here, we apply for the first time ANNs, to discriminate the vocal repertoire in a primate species, Eulemur macaco macaco. We designed an automatic procedure to extract both spectral and temporal features from signals, and performed a comparative analysis between a supervised Multilayer Perceptron and two statistical approaches commonly used in primatology (Discriminant Function Analysis and Cluster Analysis), in order to explore pros and cons of these methods in bioacoustic classification. Our results show that ANNs were able to recognize all seven vocal categories previously described (92.5-95.6%) and perform better than either statistical analysis (76.1-88.4%). The results show that ANNs can provide an effective and robust method for automatic classification also in primates, suggesting that neural models can represent a valuable tool to contribute to a better understanding of primate vocal communication. The use of neural networks to identify primate vocalizations and the further development of this approach in studying primate communication are discussed.
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Affiliation(s)
- Luca Pozzi
- Dipartimento di Biologia Animale e dell'Uomo, Università di Torino, Italy.
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35
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Bouchet H, Pellier AS, Blois-Heulin C, Lemasson A. Sex differences in the vocal repertoire of adult red-capped mangabeys (Cercocebus torquatus): A multi-level acoustic analysis. Am J Primatol 2010; 72:360-75. [PMID: 20052691 DOI: 10.1002/ajp.20791] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Sex differences in the vocal behavior of nonhuman primates can take various forms: sex-specific call types, differential production of shared call types, or sex discrepancy in phonation. Also, a growing literature is evidencing that systematically analyzing the vocal repertoires of primates at the call level might lead to underestimating their communicative abilities. Here, we present an extensive multi-level analysis of the still unknown vocal repertoire of adult red-capped mangabeys (Cercocebus torquatus), with a special emphasis on sex differences. We collected recordings from seven adult males and seven adult females housed in captivity. We present a structurally-based classification of mangabey calls that we cross-validated by an analysis of the associated contexts of emission. We found 12 sound units (including six sex-specific) that were concatenated to form eight call types (including four sex-specific), which were produced either singularly or in sequences composed of one ("repetition") or several ("combination") call types. We extracted organizational principles that ruled call composition and calling patterns. This revealed a high degree of potentially meaningful variability in terms of semantics and syntax. Male-female discrepancy in terms of phonation could be related to morphological dimorphism and would enable listeners to behave appropriately according to the sex of the caller. Sex differences in repertoire size, structural gradation, and call usage could reflect specificities of male-female social roles. We discuss the pertinence of these sex differences according to social system and habitat quality.
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Affiliation(s)
- Hélène Bouchet
- UMR EthoS, Ethologie animale et humaine, Université de Rennes, CNRS, Station Biologique de Paimpont, France.
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36
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Giacoma C, Sorrentino V, Rabarivola C, Gamba M. Sex Differences in the Song of Indri indri. INT J PRIMATOL 2010. [DOI: 10.1007/s10764-010-9412-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Spillmann B, Dunkel LP, van Noordwijk MA, Amda RNA, Lameira AR, Wich SA, van Schaik CP. Acoustic Properties of Long Calls Given by Flanged Male Orang-Utans (Pongo pygmaeus wurmbii) Reflect Both Individual Identity and Context. Ethology 2010. [DOI: 10.1111/j.1439-0310.2010.01744.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Arnedo LF, Mendes FDC, Strier KB. Sex differences in vocal patterns in the northern muriqui (Brachyteles hypoxanthus). Am J Primatol 2010; 72:122-8. [PMID: 19885910 DOI: 10.1002/ajp.20761] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We investigated whether sex differences in spatial dynamics correlate with rates of staccato and neigh vocalizations in northern muriquis (Brachyteles hypoxanthus) at the Reserva Particular do Patrimônio Natural-Feliciano Miguel Abdala, Minas Gerais, Brazil. A total of 2,727 10 min focal subject samples were collected on 32 adult females and 31 adult males between April 2007 and March 2008. Compared with males, females spent a significantly lower proportion of their time in proximity to other group members and gave staccatos at significantly higher rates while feeding, resting, and traveling. Conversely, males emitted neigh vocalizations at significantly higher rates than females when feeding and resting only. Both sexes gave significantly more staccatos when feeding than when they were engaged in other activities, but their respective rates of neighs did not vary across activities. Both females and males emitted staccato vocalizations at significantly higher rates during times of the year when preferred foods were scarce, but no seasonal differences in the rates of neigh vocalizations were observed in either sex. Females and males showed a reduction in the number of neighbors following staccato vocalizations and an increase in the number of neighbors following neigh vocalizations. Our findings of sex differences in the rates of staccato and neigh vocalizations and the effects of these vocalizations on interindividual spacing are consistent with sex differences in spatial dynamics, and confirm the role of vocal communication in mediating spatial associations in this species.
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Affiliation(s)
- Luisa F Arnedo
- Department of Anthropology, University of Wisconsin-Madison, 1180 Observatory Drive, Madison, WI 53706, USA.
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Acoustic features to arousal and identity in disturbance calls of tree shrews (Tupaia belangeri). Behav Brain Res 2009; 203:223-31. [PMID: 19445967 DOI: 10.1016/j.bbr.2009.05.007] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2009] [Revised: 05/05/2009] [Accepted: 05/08/2009] [Indexed: 11/23/2022]
Abstract
Across mammalian species, comparable morphological and physiological constraints in the production of airborne vocalisations are suggested to lead to commonalities in the vocal conveyance of acoustic features to specific attributes of callers, such as arousal and individual identity. To explore this hypothesis we examined intra- and interindividual acoustic variation in chatter calls of tree shrews (Tupaia belangeri). The calls were induced experimentally by a disturbance paradigm and related to two defined arousal states of a subject. The arousal state of an animal was primarily operationalised by the habituation of the subject to a new environment and additionally determined by behavioural indicators of stress in tree shrews (tail-position and piloerection). We investigated whether the arousal state and indexical features of the caller, namely individual identity and sex, are conveyed acoustically. Frame-by-frame videographic and multiparametric sound analyses revealed that arousal and identity, but not sex of a caller reliably predicted spectral-temporal variation in sound structure. Furthermore, there was no effect of age or body weight on individual-specific acoustic features. Similar results in another call type of tree shrews and comparable findings in other mammalian lineages provide evidence that comparable physiological and morphological constraints in the production of airborne vocalisations across mammals lead to commonalities in acoustic features conveying arousal and identity, respectively.
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Ey E, Rahn C, Hammerschmidt K, Fischer J. Wild Female Olive Baboons Adapt their Grunt Vocalizations to Environmental Conditions. Ethology 2009. [DOI: 10.1111/j.1439-0310.2009.01638.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Rendall D, Notman H, Owren MJ. Asymmetries in the individual distinctiveness and maternal recognition of infant contact calls and distress screams in baboons. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2009; 125:1792-805. [PMID: 19275336 PMCID: PMC2736728 DOI: 10.1121/1.3068453] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2008] [Revised: 12/11/2008] [Accepted: 12/12/2008] [Indexed: 05/27/2023]
Abstract
A key component of nonhuman primate vocal communication is the production and recognition of clear cues to social identity that function in the management of these species' individualistic social relationships. However, it remains unclear how ubiquitous such identity cues are across call types and age-sex classes and what the underlying vocal production mechanisms responsible might be. This study focused on two structurally distinct call types produced by infant baboons in contexts that place a similar functional premium on communicating clear cues to caller identity: (1) contact calls produced when physically separated from, and attempting to relocate, mothers and (2) distress screams produced when aggressively attacked by other group members. Acoustic analyses and field experiments were conducted to examine individual differentiation in single vocalizations of each type and to test mothers' ability to recognize infant calls. Both call types showed statistically significant individual differentiation, but the magnitude of the differentiation was substantially higher in contact calls. Mothers readily discriminated own-offspring contact calls from those of familiar but unrelated infants, but did not do so when it came to distress screams. Several possible explanations for these asymmetries in call differentiation and recognition are considered.
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Affiliation(s)
- Drew Rendall
- Department of Psychology, University of Lethbridge, Lethbridge, Alberta, Canada.
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Charlton BD, McComb K, Reby D. Free-Ranging Red Deer Hinds Show Greater Attentiveness to Roars with Formant Frequencies Typical of Young Males. Ethology 2008. [DOI: 10.1111/j.1439-0310.2008.01539.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Charlton BD, Reby D, McComb K. Effect of combined source (F0) and filter (formant) variation on red deer hind responses to male roars. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2008; 123:2936-2943. [PMID: 18529210 DOI: 10.1121/1.2896758] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Studying female response to variation in single acoustic components has provided important insights into how sexual selection operates on male acoustic signals. However, since vocal signals are typically composed of independent components, it is important to account for possible interactions between the studied parameter and other relevant acoustic features of vocal signals. Here, two key components of the male red deer roar, the fundamental frequency and the formant frequencies (an acoustic cue to body size), are independently manipulated in order to examine female response to calls characterized by different combinations of these acoustic components. The results revealed that red deer hinds showed greater overall attention and had lower response latencies to playbacks of roars where lower formants simulated larger males. Furthermore, female response to male roars simulating different size callers was unaffected by the fundamental frequency of the male roar when it was varied within the natural range. Finally, the fundamental frequency of the male roar had no significant separate effect on any of the female behavioral response categories. Taken together these findings indicate that directional intersexual selection pressures have contributed to the evolution of the highly mobile and descended larynx of red deer stags and suggest that the fundamental frequency of the male roar does not affect female perception of size-related formant information.
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Affiliation(s)
- Benjamin D Charlton
- Department of Psychology, School of Life Sciences, University of Sussex, BN1 9QH, United Kingdom.
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Rendall D, Vasey PL, McKenzie J. The Queen's English: an alternative, biosocial hypothesis for the distinctive features of "gay speech". ARCHIVES OF SEXUAL BEHAVIOR 2008; 37:188-204. [PMID: 18085431 DOI: 10.1007/s10508-007-9269-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Popular stereotypes concerning the speech of homosexuals typically attribute speech patterns characteristic of the opposite-sex, i.e., broadly feminized speech in gay men and broadly masculinized speech in lesbian women. A small body of recent empirical research has begun to address the subject more systematically and to consider specific mechanistic hypotheses to account for the potentially distinctive features of homosexual speech. Results do not yet fully endorse the stereotypes but they do not entirely discount them either; nor do they cleanly favor any single mechanistic hypothesis. To contribute to this growing body of research, we report acoustic analyses of 2,875 vowel sounds from a balanced set of 125 speakers representing heterosexual and homosexual individuals of each sex from southern Alberta, Canada. Analyses focused on voice pitch and formant frequencies which together determine the principle perceptual features of vowels. There was no significant difference in mean voice pitch between heterosexual and homosexual men or between heterosexual and homosexual women, but there were significant differences in the formant frequencies of vowels produced by both homosexual groups compared to their heterosexual counterparts. Formant frequency differences were specific to only certain vowel sounds and some could be attributed to basic differences in body size between heterosexual and homosexual speakers. The remaining formant frequency differences were not obviously due to differences in vocal tract anatomy between heterosexual and homosexual speakers, nor did they reflect global feminization or masculinization of vowel production patterns in homosexual men and women, respectively. The vowel-specific differences observed could reflect social modeling processes in which only certain speech patterns of the opposite-sex, or of same-sex homosexuals, are selectively adopted. However, we introduce an alternative biosocial hypothesis, specifically that the distinctive, vowel-specific features of homosexual speakers relative to heterosexual speakers arise incidentally as a product of broader psychobehavioral differences between the two groups that are, in turn, continuous with and flow from the physiological processes that affect sexual orientation to begin with.
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Affiliation(s)
- Drew Rendall
- Department of Psychology, University of Lethbridge, Lethbridge, Alberta, Canada.
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Weiss BM, Symonds H, Spong P, Ladich F. Intra- and intergroup vocal behavior in resident killer whales, Orcinus orca. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2007; 122:3710-6. [PMID: 18247778 DOI: 10.1121/1.2799907] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Vocal communication within and between groups of individuals has been described extensively in birds and terrestrial mammals, however, little is known about how cetaceans utilize their sounds in their natural environment. Resident killer whales, Orcinus orca, live in highly stable matrilines and exhibit group-specific vocal dialects. Single call types cannot exclusively be associated with particular behaviors and calls are thought to function in group identification and intragroup communication. In the present study call usage of three closely related matrilines of the Northern resident community was compared in various intra- and intergroup contexts. In two out of the three matrilines significant changes in vocal behavior depending both on the presence and identity of accompanying whales were found. Most evidently, family-specific call subtypes, as well as aberrant and variable calls, were emitted at higher rates, whereas "low arousal" call types were used less in the presence of matrilines from different pods, subclans, or clans. Ways in which the observed changes may function both in intra- and intergroup communication.
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Affiliation(s)
- Brigitte M Weiss
- Department of Behavioural Biology, University of Vienna, A-1090 Vienna, Austria
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Abstract
Surprisingly little is known about the role of acoustic cues in mammal female mate choice. Here, we examine the response of female red deer (Cervus elaphus) to male roars in which an acoustic cue to body size, the formants, has been re-scaled to simulate different size callers. Our results show that oestrous red deer hinds prefer roars simulating larger callers and constitute the first evidence that female mammals use an acoustic cue to body size in a mate choice context. We go on to suggest that sexual selection through female mating preferences may have provided an additional selection pressure along with male-male competition for broadcasting size-related information in red deer and other mammals.
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Affiliation(s)
- Benjamin D Charlton
- Department of Psychology, School of Life Sciences, University of Sussex, Brighton BN1 9QH, UK.
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Pfefferle D, West PM, Grinnell J, Packer C, Fischer J. Do acoustic features of lion, Panthera leo, roars reflect sex and male condition? THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2007; 121:3947-53. [PMID: 17552741 DOI: 10.1121/1.2722507] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Long distance calls function to regulate intergroup spacing, attract mating partners, and/or repel competitors. Therefore, they may not only provide information about the sex (if both sexes are calling) but also about the condition of the caller. This paper provides a description of the acoustic features of roars recorded from 18 male and 6 female lions (Panthera leo) living in the Serengeti National park, Tanzania. After analyzing whether these roars differ between the sexes, tests whether male roars may function as indicators of their fighting ability or condition were conducted. Therefore, call characteristics were tested for relation to anatomical features as size, mane color, or mane length. Call characteristics included acoustic parameters that previously had been implied as indicators of size and fighting ability, e.g., call length, fundamental frequency, and peak frequency. The analysis revealed differences in relation to sex, which were entirely explained by variation in body size. No evidence that acoustic variables were related to male condition was found, indicating that sexual selection might only be a weak force modulating the lion's roar. Instead, lion roars may have mainly been selected to effectively advertise territorial boundaries.
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Affiliation(s)
- Dana Pfefferle
- Research Group Cognitive Ethology, German Primate Center, Kellnerweg 4, 37077 Göttingen, Germany.
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Ey E, Pfefferle D, Fischer J. Do age- and sex-related variations reliably reflect body size in non-human primate vocalizations? A review. Primates 2007; 48:253-67. [PMID: 17226064 DOI: 10.1007/s10329-006-0033-y] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2006] [Accepted: 11/27/2006] [Indexed: 10/23/2022]
Abstract
In vocal communication, the mechanisms of sound production are well understood. The length of the vocal folds determines the minimum fundamental frequency, while the size and the shape of the vocal tract affect its filtering characteristics and hence, the resonant frequencies. Both measures-vocal fold length and vocal tract length-are related to body size and therefore, acoustic features are expected to vary with body size. Because direct measures of body size are difficult to obtain from free-ranging animals, age and sex have often been used as proxies. We surveyed studies which included direct measures of size or weight, and also studies in which only age and/or sex differences were examined. The main purpose was to examine whether age- and sex-related variations in acoustic features meet the predictions generated from our knowledge about sound production. Our survey revealed that compared to smaller animals, larger animals utter longer calls, with a lower fundamental frequency, with smaller formant dispersion, and with the energy concentrated in lower frequencies. Age and sex reliably reflect the influence of body size on acoustic features when gross size differences are examined. However, within age- and sex classes, this relationship may break down. In addition to body size, other factors such as internal state or social context may also influence the structure of vocal signals and highlight the richness of information in calls that is potentially available to listeners.
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Affiliation(s)
- E Ey
- Research Group Cognitive Ethology, German Primate Centre, Kellnerweg 4, 37077 Göttingen, Germany.
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