坡地酸性硫酸鹽土壤之保育問題

International audienceA standard way of describing the vocal behaviour of nonhuman primates is to classify the vocal repertoire as either graded or discrete. We analysed a large database of calls given by adult males of a primate considered a typical example for discrete vocal behaviour, the forest-dwelling Campbell's monkeys, Cercopithecus campbelli. We recorded vocal responses from several dozen individuals to their main predators, crowned eagles and leopards. Using cluster analysis techniques, we found two main call types, which were modified further by optional affixation of an inflexible vocal structure. It was possible to force the four call types into eight subtypes, with various degrees of gradedness. When taking context into account, we found that acoustically discrete and nonaffixed calls tended to be given right after discovering a predator, while acoustically graded and affixed calls were given during later parts of a predator encounter and to nonpredatory disturbances. In sum, our results suggest that classifications of primate vocal repertoires as either discrete or graded are likely to be meaningless, as communicatively relevant acoustic variation can be present within seemingly discrete call types

Adult human perception of distress in the cries of bonobo, chimpanzee, and human infants

Understanding the extent to which humans perceive the emotional state of animals has both theoretical and practical implications. While recent studies indicate that natural selection has led to some convergence of emotion coding among vertebrate species (including humans), highlighting the interspecific value of emotional signals, it has also been argued that interspecific communication of emotions can fail due to species-specific signalling traits impairing information decoding and/or absence of familiarity with heterospecific communication systems. In this article, we show that human listeners pay attention to the mean pitch of vocalizations when asked to rate the distress level expressed by human baby cries, and that they use a similar pitch scale to rate the emotional level of baby non-human ape (bonobo and chimpanzee) distress calls. As a consequence, the very high-pitched bonobo infant calls were systematically rated as expressing overall high distress levels despite being recorded in contexts eliciting various stress intensity. Conversely, chimpanzee infant calls – which are characterized by a relatively lower pitch – were systematically rated as expressing relatively lower distress levels. These results indicate that, in the absence of exposure/familiarity, our spontaneous ability to range the emotional content of vocalizations in closely related ape species remains biased by basic frequency differences, suggesting that the absolute interspecific value of emotional signals should not be overestimated

Enduring voice recognition in bonobos

We would like to thank the French Ministère de l’Enseignement Supérieur et de la Recherche (PhD grant to SK), the Université de Saint-Etienne (research sabbaticals to FL and NM, visiting professorship to KZ and research funding) and the European Research Council (KZ grant PRILANG 283871).Long-term social recognition is vital for species with complex social networks, where familiar individuals can encounter one another after long periods of separation. For non-human primates who live in dense forest environments, visual access to one another is often limited, and recognition of social partners over distances largely depends on vocal communication. Vocal recognition after years of separation has never been reported in any great ape species, despite their complex societies and advanced social intelligence. Here we show that bonobos, Pan paniscus, demonstrate reliable vocal recognition of social partners, even if they have been separated for five years. We experimentally tested bonobos' responses to the calls of previous group members that had been transferred between captive groups. Despite long separations, subjects responded more intensely to familiar voices than to calls from unknown individuals - the first experimental evidence that bonobos can identify individuals utilising vocalisations even years after their last encounter. Our study also suggests that bonobos may cease to discriminate between familiar and unfamiliar individuals after a period of eight years, indicating that voice representations or interest could be limited in time in this species.Publisher PDFPeer reviewe

L’ information “identité individuelle” dans la communication vocale du bonobo : de l’émetteur au récepteur

Identity information is vital for highly social species as it facilitates individual recognition and allows for differentiation between social partners in many contexts, such as dominance hierarchies, territorial defence, mating and parent-offspringidentification and group cohesion and coordination. In many species vocalisations can be the most effective communication channel through complex environments and over long-distances and are encoded with the stable features of an individual’s voice. Associations between these individual vocal signatures and accumulated social knowledge about conspecifics can greatly increase an animal’s fitness, as it facilitates adaptively constructive social decisions. This thesis investigates the encoding and decoding of identity information in the vocal communication system of the bonobo, Pan paniscus. We firstly investigated the stability of vocal signatures across the five most common call types in the bonobo vocal repertoire. Results showed that while all call types have the potential to code identity information, loud calls used during times of high arousal and for distance communication have the strongest individual vocal signatures. Following the first study, we investigated if social familiarity and relatedness affect the acoustic features that code individual information in the bark call type. Overall, we found strong evidence for vocal convergence, and specifically, that individuals who are related and familiar, independently from one another, are more vocally similar to one another than unrelated and unfamiliar individuals. In a final study we tested if bonobos are capable of using the encoded identity information to recognise past group members that they no longer live with. Through a series playback experiments we demonstrated that bonobos are capable of recognising familiar individuals from vocalisations alone even after years of separation. Collectively, the results of this thesis show that the encoding and decoding of identity information in bonobo vocalisations is a dynamic system, subject to modification through social processes but robust enough to allow for individual recognition over time. In conclusion these studies contribute to a better understanding of the vocal communication system of a non-human primate species with a unique and complex social networkL’information "identité individuelle" est essentielle chez les espèces fortement sociales car elle permet la reconnaissance individuelle et la différenciation des partenaires sociaux dans de nombreux contextes tels que les relations de dominance, les relations mère-jeunes, la défense territoriale, ou encore participe à la cohésion et coordination de groupe. Chez de nombreuses espèces, le canal audio est l’une des voies les plus efficaces de communication dans des environnementscomplexes et à longue distance. Les vocalisations sont empreintes de caractéristiques acoustiques propres à la voix de chaque individu. La combinaison entre ces signatures vocales individuelles et la connaissance sociale accumulée sur les congénères peut grandement favoriser la valeur sélective des animaux, en facilitant notamment les prises de décisions sociales les plus adaptées. Le but de ma recherche est d’étudier le codage et décodage de l’information "identité individuelle" du système vocal de communication du bonobo, Pan paniscus. Premièrement, nous avons recherché la stabilité des signatures vocales des cinq types de cris les plus courants du répertoire du bonobo. Nous avons trouvé que, bien que ces cinq types de cris aient le potentiel de coder l’information individuelle, les cris les plus forts émis dans des contextes d’excitation intense et de communication à longue distance ont les signatures vocales individuelles les plus marquées. Deuxièmement, nous avons étudié l’effet de la familiarité sociale et des liens de parenté sur les caractéristiquesacoustiques qui codent l’information individuelle dans un type de cri "bark". Nous avons mis en évidence l’existence d’une forte convergence vocale. Les individus apparentés et familiers, et indépendamment l’un de l’autre, présentent plus desimilarités vocales qu’entre des individus non apparentés et non familiers. Enfin, dans une troisième étude, nous avons testé la capacité des bonobos à utiliser l’information "identité individuelle" codée dans les vocalisations pour discriminer la voix d’anciens partenaires sociaux avec qui ils ne vivent plus. Par une série d’expériences de repasse, nous avons démontré que les bonobos étaient capables de reconnaître la voix d’individus familiers sur la seule base de l’acoustique, et cela même après des années de séparation. L’ensemble de ce travail de thèse montre que le codage et décodage de l’information "identité individuelle" chez le bonobo est un système dynamique, sujet à modification avec l’environnement social mais suffisamment fiable pour permettre la reconnaissance individuelle au cours du temps. En conclusion cette étude participe à une meilleure compréhension du système de communication vocale chez un primate non-humain forestier, au réseau social unique et complex

Identity information in bonobo vocal communication: from sender to receiver

Identity information is vital for highly social species as it facilitates individual recognition and allows for differentiation between social partners in many contexts, such as dominance hierarchies, territorial defence, mating and parent-offspring identification, and group cohesion and coordination. For many species vocalisations can be the most effective communication channel in complex environments and over long-distances and are encoded with the stable features of an individual’s voice. Associations between these individual vocal signatures and accumulated social knowledge about conspecifics can greatly increase an animal’s fitness, as it facilitates adaptively constructive social decisions. This thesis investigates the encoding and decoding of identity information in the vocal communication system of the bonobo, Pan paniscus. We firstly investigated the stability of vocal signatures across the five most common call types in the bonobo vocal repertoire. Results showed that while all call types have the potential to code identity information, loud calls used during times of high arousal and for distance communication have the strongest individual vocal signatures. Following the first study, we investigated if social familiarity and relatedness affect the acoustic features that code individual information in the bark call type. Overall, we found strong evidence for vocal convergence, and specifically, that individuals who are related and familiar, independently from one another, are more vocally similar to one another than unrelated and unfamiliar individuals. In a final study, we tested if bonobos are capable of using the encoded identity information to recognise past group members that they no longer live with. Through a series playback experiments we demonstrated that bonobos are capable of recognising familiar individuals from vocalisations alone even after years of separation. Collectively, the results of this thesis show that the encoding and decoding of identity information in bonobo vocalisations is a dynamic system, subject to modification through social processes but robust enough to allow for individual recognition over time. In conclusion, these studies contribute to a better understanding of the vocal communication system of a non-human primate species with a unique and complex social network

On the -oo ‘suffix’ of Campbell’s monkeys (C. campbelli)

http://www.mitpressjournals.org/loi/lingInternational audienceOuattara et al. (2009a,b) make the novel claim that Campbell’s monkey alarm calls demonstrate a simple pattern of linguistic morphology. The authors observe that there are at least two distinct alarm calls (called krak and hok) that are used in two different predatory contexts, and that each may be followed by a low frequency sound (called -oo) that alters the meaning of both calls in predictable ways, allowing contexts with reduced level of threat. In light of these facts, -oo is analyzed as a meaning-bearing, combinatorial unit. However, the claim that a non-human communication system has a combinatorial system (however primitive) is rare in the literature (see x5 for related patterns), and, indeed, is antithetical to certain claims that structural hierarchy is unique to human language (e.g., Bolhuis et al. 2014). Moreover, it has been noted (Schlenker et al. 2014) that there is redundancy between the apparent semantic contribution of -oo and the semantic contribution of a variety of other signal manipulations (e.g. calling rate) that are easiest to explain via non-compositional mechanisms. These facts warrant particular caution when evaluating the pattern as a possible counterexample to generalizations about human language. Thus, in this squib, we examine the compositional hypothesis further. As counterpoint, we consider a class of more conservative hypotheses in which -oo does not itself bear meaning, but instead arises as the side effect of other articulatory processes that noncompositionally affect call meaning. Key to such hypotheses is the premise that -oo is articulatorily parasitic on another phonetic process. A major contribution of this squib is thus phonetic: considering the acoustic properties of -oo, we conclude that complex calls (krakoo and hokoo) are produced with a two pulses of a single breath-group. Critically, the production of these complex calls requires an additional articulatory gesture and thus an increase in articulatory effort. An increase in articulatory effort would not be expected on an analysis in which -oo arises as a phonetic side effect; we accordingly reject these alternate hypotheses, thus strengthening the robustness of the combinatorial analysis

Rupture in long-term vocal recognition of past social partners in bonobos

Bonobos live in dense forest habitats where visual communication is often limited rendering vocal signals important to regulate their social interactions. Moreover their fluid fission-fusion society requires contact over long distances, suggesting that vocal signals of group members are recognised individually. To this end, individual signatures should be reliably encoded in vocal interactions and memorised by recipients over long periods. In this study we investigated individual vocal recognition of group members that had been separated for long periods of time (two to nine years) with varying relationships. In the wild, long-term separation happens regularly, usually in relation to female migration. In captivity, the same process takes place during the transfer of individuals between zoos, mimicking wild migration. We simulated bonobo transfers by broadcasting contact calls of familiar or unfamiliar individuals to our subjects, thus imitating the arrival of new group members. In total, we tested 15 bonobos (> 10 years old) from three European zoos and compared their behavioural responses. We found that bonobos responded differently to familiar voices than to stranger voices, even after prolonged separation. However, the recognition of past partners appears to diminish after being separated for 6-8 years. This interesting result will be discussed regarding to the social needs in bonobos

Les bonobos se rappellent-ils la voix de leurs anciens partenaires ?

Cet article présente notre étude sur la reconnaissance vocale à long terme des partenaires sociaux chez les bonobos Pan paniscus. Ces résultats ont été publiés en 2016 dans la revue Scientific Reports 6 : 22046 | https://doi.org/10.1038/srep22046 et, avec l'accord de tous les co-auteurs, nous proposons ici une version française de cette étude pour la Revue de Primatologie. La reconnaissance sociale à long terme est vitale pour les espèces vivant dans des réseaux sociaux complexes et dans lesquels des individus familiers peuvent se rencontrer à nouveau après de longues périodes de séparation. Chez les primates non humains qui vivent dans des environnements forestiers denses, la visibilité est souvent limitée ; et, la reconnaissance des partenaires sociaux à longue distance dépend de la communication vocale. Etonnamment, la reconnaissance vocale de partenaires après des années de séparation n'a jamais été testée chez aucune espèce de grand singe, malgré l’organisation complexe de leur société et leur intelligence sociale. Nous montrons ici que les bonobos, Pan paniscus, sont capables d’une reconnaissance vocale fiable de leurs partenaires sociaux, et cela même s'ils ont été séparés pendant cinq ans. Nous avons testé expérimentalement les réponses de bonobos aux vocalisations d’anciens membres de leur groupe qui avaient été transférés entre parcs zoologiques. Malgré de longues périodes de séparation, les sujets ont répondu plus intensément aux voix familières qu'aux voix d'individus étrangers. Cette observation démontre expérimentalement que les bonobos peuvent discriminer des individus sur la seule base d’indice acoustique même des années après leur dernière rencontre. Notre étude suggère également que les bonobos peuvent cesser de faire la distinction entre des individus familiers et non familiers après une période de huit ans, indiquant que les représentations vocales ou l'intérêt pourraient être limités dans le temps chez cette espèce.In the present paper, we present our finding about the long-term vocal recognition of past social partners in bonobos Pan paniscus. These results have been published in 2016 in the journal Scientific Reports, 6:22046 | https://doi.org/10.1038/srep22046, and with the agreement of the co-authors, we propose here a French version on this study for the Revue de Primatologie. Long-term social recognition is vital for species with complex social networks, where familiar individuals can encounter one another after long periods of separation. For non-human primates who live in dense forest environments, visual access to one another is often limited, and recognition of social partners over distances largely depends on vocal communication. Vocal recognition after years of separation has never been reported in any great ape species, despite their complex societies and advanced social intelligence. Here we show that bonobos demonstrate reliable vocal recognition of social partners, even if they have been separated for five years. We experimentally tested bonobos’ responses to the calls of previous group members that had been transferred between captive groups. Despite long separations, subjects responded more intensely to familiar voices than to calls from unknown individuals—the first experimental evidence that bonobos can identify individuals utilizing vocalisations even years after their last encounter. Our study also suggests that bonobos may cease to discriminate between familiar and unfamiliar individuals after a period of eight years, indicating that voice representations or interest could be limited in time in this species

Enduring voice recognition in bonobos

Long-term social recognition is vital for species with complex social networks, where familiar individuals can encounter one another after long periods of separation. For non-human primates who live in dense forest environments, visual access to one another is often limited, and recognition of social partners over distances largely depends on vocal communication. Vocal recognition after years of separation has never been reported in any great ape species, despite their complex societies and advanced social intelligence. Here we show that bonobos, Pan paniscus, demonstrate reliable vocal recognition of social partners, even if they have been separated for five years. We experimentally tested bonobos' responses to the calls of previous group members that had been transferred between captive groups. Despite long separations, subjects responded more intensely to familiar voices than to calls from unknown individuals - the first experimental evidence that bonobos can identify individuals utilising vocalisations even years after their last encounter. Our study also suggests that bonobos may cease to discriminate between familiar and unfamiliar individuals after a period of eight years, indicating that voice representations or interest could be limited in time in this species.</p

Improving the workflow to crack Small, Unbalanced, Noisy, but Genuine (SUNG) datasets in bioacoustics: The case of bonobo calls.

Despite the accumulation of data and studies, deciphering animal vocal communication remains challenging. In most cases, researchers must deal with the sparse recordings composing Small, Unbalanced, Noisy, but Genuine (SUNG) datasets. SUNG datasets are characterized by a limited number of recordings, most often noisy, and unbalanced in number between the individuals or categories of vocalizations. SUNG datasets therefore offer a valuable but inevitably distorted vision of communication systems. Adopting the best practices in their analysis is essential to effectively extract the available information and draw reliable conclusions. Here we show that the most recent advances in machine learning applied to a SUNG dataset succeed in unraveling the complex vocal repertoire of the bonobo, and we propose a workflow that can be effective with other animal species. We implement acoustic parameterization in three feature spaces and run a Supervised Uniform Manifold Approximation and Projection (S-UMAP) to evaluate how call types and individual signatures cluster in the bonobo acoustic space. We then implement three classification algorithms (Support Vector Machine, xgboost, neural networks) and their combination to explore the structure and variability of bonobo calls, as well as the robustness of the individual signature they encode. We underscore how classification performance is affected by the feature set and identify the most informative features. In addition, we highlight the need to address data leakage in the evaluation of classification performance to avoid misleading interpretations. Our results lead to identifying several practical approaches that are generalizable to any other animal communication system. To improve the reliability and replicability of vocal communication studies with SUNG datasets, we thus recommend: i) comparing several acoustic parameterizations; ii) visualizing the dataset with supervised UMAP to examine the species acoustic space; iii) adopting Support Vector Machines as the baseline classification approach; iv) explicitly evaluating data leakage and possibly implementing a mitigation strategy