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Infant vocalisations are uniquely salient sounds in the environment. They universally attract attention and compel the listener to respond with speed and care. They provide a wealth of information to parents about their infant’s needs and affective state. There is a scientific consensus that early parenting has a profound impact on child development. In particular, the sensitivity with which parents respond to their infant’s communicative cues has been shown to affect cognitive and socio-emotional outcomes. The mechanisms underlying such sensitivity are not well understood. In this thesis, adults’ sensitivity to infant cues will be considered in terms of two components, the ‘promptness’ and ‘appropriateness’ of responses, as originally conceptualised by Bell and Ainsworth (1972). Promptness of responses is considered in terms of adults’ ability to move with speed and effort after listening to infant vocalisations. Appropriateness, on the other hand, is considered in terms of adults’ ability to differentiate between functionally significant parameters in infant vocalisations. The effect of modifiable environmental factors on the promptness and appropriateness of responses is also investigated. Finally, a focused investigation of the brain basis of responses to infant vocalisations is presented. Overall, findings demonstrated that infant vocalisations undergo privileged, specialised processing in the adult brain. After hearing an infant cry, adults with and without depression were found to move with greater coordination and effort. Adults were also found to be attuned to subtle parameters in infant cries. This sensitivity was shown to be affected by two participant-level factors, depression and previous musical training. Furthermore, this sensitivity could be enhanced through intervention, as evidenced by findings from short-term, perceptual discrimination training. The notion of privileged processing of infant vocalisations is further supported by evidence of early discrimination of infant sounds in a survival-related subcortical brain structure. Future directions for this work include directly relating current experimental measures of adults’ responses to infant cues with parental sensitivity to infant communication during dynamic interactions. Translating current findings into applied settings would require an investigation of the effects of factors such as musical and perceptual training on sensitivity to infant cues in at-risk populations, such as mothers and fathers with depression. Lastly, an increased understanding of the brain basis of adults’ sensitivity to infant cues will provide insight into our greatest challenge: parenting our young.

Le Quetzal Resplendissant Pharomachrus mocinno est une espèce d’oiseau tropical considérée fortement menacée par la perte de son habitat due aux activités humaines. Le Quetzal Resplendissant joue un rôle important de disperseur de graines et constitue le centre de la culture maya passée et présente. Les recherches sur cette espèce couvrent plusieurs aspects de son histoire naturelle et de sa biologie. Néanmoins, à ce jour, il n’y a aucune description détaillée du comportement et de l’écologie acoustiques de cette espèce, condition préalable à une conservation efficace de l'espèce. L’objectif de cette thèse a été d’étudier tout particulièrement le comportement et l’écologie acoustique de P. mocino dans la forêt nuageuse du Guatemala. Une analyse détaillée des vocalisations de P. mocinno, incluant des expériences de propagation de ses vocalisations dans son habitat, a permis d’identifier deux types de vocalisations destinés à la communication à longue distance et deux autres types de vocalisations destinés à la communication à courte distance. La quantification des différences dans les vocalisations territoriales des deux sous-espèces de Quetzals Resplendissants, P. m. mocinno (partie nord de l’Amérique centrale et sud du Mexique) et P. m. costaricensis (sud de l'Amérique centrale) a révélé de nettes différences entre les sous-espèces, ce qui conforterait l'hypothèse d’espèces distinctes. L'observation de l'espèce dans la canopée dense est difficile et la manipulation des individus est controversée en raison de sa grande importance culturelle. De fait, un système acoustique automatique a été mis au point pour suivre l’espèce de manière non invasive. Le système s'est avéré efficace et a produit des résultats révélant des profils de suivis acoustiques en partie dépendants de variables environnementales. Enfin, la communauté acoustique des oiseaux à laquelle P. mocinno appartient a été analysée afin d’évaluer les interactions interspécifiques de compétition. Les recherches développées ici devraient aider aux décisions de conservation futures concernant le Quetzal Resplendissant et son habitat, la forêt nuageuse. Cette recherche montre également que l'écoacoustique peut constituer une stratégie utile pour aborder les problèmes d'écologie et de conservation dans les zones tropicales. / The Resplendent Quetzal Pharomachrus mocinno is a tropical bird considered in a high risk of danger. Degradation of its habitat caused by human activities is the principal menace. The Resplendent Quetzal is important as seed disperser and is the centre of the past and present Mayan culture. The available studies about the species have covered aspects of the natural history and biology. Nevertheless, the description of the acoustic behaviour and ecology, a prerequisite for the conservation of the species, was not available. The general aim of this PhD thesis was to investigate the acoustic behaviour and ecology of P. mocinno in the cloud forest of Guatemala. A detailed analysis of P. mocinno vocalizations, including propagation experiments of these vocalizations in its habitat, led to identify two vocalizations intended for long range, and two for short range communication. Quantification of acoustic parameters in territorial vocalizations of the two subspecies of the Resplendent Quetzal, P. m. mocinno (north part of Central America and Chiapas) and P. m. costaricensis (south part of Central America), revealed clear differences between the subspecies, that could support a species separation hypothesis. . The observation of the species in the dense canopy is difficult and manipulation of individuals is controversial due to its high cultural importance. Then, an automatic acoustic system was developed as a method to study the species in a non-invasive way. The system proved to be efficient and returned results that revealed acoustic patterns linked to environmental variables. Finally, the acoustic community of other bird species P. mocinno belongs to was analysed so that interspecific competition interactions could be assessed. The research here developed should help in future conservation decisions about the Resplendent Quetzal and its habitat, the cloud forest. This research also illustrates that ecoacoustics can be a valuable strategy to tackle ecology and conservation questions in tropical areas.

La prise de décision est un processus indispensable et vital pour les mammifères. Elle permet à l’individu de s’adapter aux changements qui s’opèrent dans son environnement et résulte de l’intégration d’informations sensorielles, émotionnelles, motivationnelles et exécutives (qui peuvent être internes ou externes à l’individu). Des études, à la fois chez le sujet humain (sujet sain, patients cérébrolésés ou atteints de pathologies psychiatriques), et sur les modèles animaux singe, rats ou souris, ont permis d’identifier le cortex préfrontal comme acteur crucial dans ces processus exécutifs complexes. La mise en place au sein de notre laboratoire d’un test d’interaction sociale permettant de générer des prises de décision rapides et adaptées en présence d’un congénère nouveau, nous a permis d’étudier les bases neurobiologiques et comportementales sous-jacentes à la prise de décision et à la flexibilité comportementale. Il est connu que les rongeurs émettent des USVs dont le rôle et les mécanismes motivationnels et/ou émotionnels restent largement inconnus à ce jour. Mon travail de thèse repose principalement sur l’identification des acteurs cérébraux de cette interaction sociale, et sur le rôle putatif des USVs. D’autre part, je me suis employé à comprendre comment les motivations naturelles (telles que la nourriture, l’exploration d’objet ou de l’environnement, et l’interaction avec un congénère) sont intégrées au canevas de prise de décision et comment elles l’influencent.Dans un premier temps, en utilisant des procédures d’imagerie cellulaire basée sur l’expression de gènes précoces (c-fos), et ce, à la fois chez des animaux contrôles et chez des animaux présentant des troubles des comportements sociaux (β2KO), nous avons pu mettre en évidence l’implication différentielle de sous-parties du cortex préfrontal chez la souris. Par la suite, la mise en place d’un logiciel spécifique d’analyse, ainsi que la modulation de l’état de motivation de l’animal lors de la tâche d’interaction sociale, nous a permis de mieux comprendre l’établissement de comportements adaptés lors de l’interaction sociale. Pour finir, en variant les contextes comportementaux, nous avons montré qu’il existe une relation étroite entre état émotionnel et motivationnel de l’animal et émission d’USVs. Notamment, les USVs semblent porter une information spécifique lors de l’interaction sociale qui reste encore largement à déterminer. / Decision-making is one of the most essential process for mammals. It allows the individual to adapt to environmental changes by the integration of sensory, emotional, motivational and executive information. Numerous studies, in human subject (healthy or not), and on animal models like monkey, rats or mice, have allowed the identification of a major actor in these complex processes: the prefrontal cortex. In our laboratory, we set up a new test, called the social interaction task -SIT-, to generate quick and adapted decision-making in presence of a new congener. This task was used to dissect neural and behavioral bases underlying decision-making and behavioral flexibility during social interaction. It is well known now that rodents emit ultrasonic vocalizations -USVs-, of which roles and mechanisms (motivational or emotional) remain largely unknown. My work was devoted to the identification of brain structures that allow flexible social interactions, and to the unraveling of the putative role(s) of USVs during SIT. I also tried to understand how natural motivations (like social interaction, exploration, and food consumption) take part in the decision-making process.First, by using cellular imaging procedure based on the expression of immediate early genes (c-fos): we were able to highlight the differential involvement of sub-areas of the prefrontal cortex in mice. Subsequently, the development of a new specific software, and the ability to modulate the motivational state of the animal, enabled us to understand better the establishment of adapted behaviors during the SIT. Finally, by varying behavioral contexts, we found a tight relationship between emotional/motivational states and USVs emissions. Notably, USVs appear to carry specific information in social interaction, and this point largely remains to be determined.

Southern right whale vocalisations recorded in Walker Bay, South Africa, between June and November 1999, were analysed to investigate the acoustic repertoire, the relationship between calling behaviour and whale presence, the proportions of vocal and silent whales, and of recorded calls from unseen whales, and the evidence for vocal individuality. This marks the first study of right whale vocalisation in South African waters. A simple matrix system with the axes acoustic contour and onset frequency described twelve call types. Analysis of call use over time indicated that some calls, as well as broadband gunshots, clustered strongly in bouts of differing lengths, and that their relative use varied over the season; the repertoire and its classification was compared with other accounts of right whale vocalisation [chapter one]. A generalised linear model explained the variation in the overall call rate in terms of the numbers of whales present, month and wind direction. The overall call rate, for each month and in all wind conditions, rose with increasing whale numbers to a plateau at between ten and fifteen whales, and then declined as whale numbers rose further, suggesting that the social motivation for vocalising was progressively reversed. An inverse linear relationship between call rate per whale and whale abundance was clearly demonstrated over the whole season, indicating that call rates were unreliable as an indicator of whale numbers [chapter two]. A dual-axis, three-element hydrophone array suspended at 5m from floating buoys was designed to assign whale vocalisations to calling whales. The array was calibrated with an overall mean error of 3°. Bearings to calling whales were calculated using correlelograms, and compared with the observed positions of whales. On average 31% of low up (upwardly inflected) calls and 11% of medium and high down (downwardly inflected) calls came from whales not sighted from the boat; up to just under half of the whales sighted from the boat were silent. This indicates the importance of integrating visual and acoustic data when estimating whale numbers [chapter three]. In characterising individuality in vocalisations, we used cluster analysis of acoustic properties of whale calls to derive the Euclidean distances (a measure of similarity) between each possible pair of calls within a continuous recording session. Calls clearly from different whales (distant call pairs) were more dissimilar than calls possibly from one whale (‘close’ call pairs), lending support to the hypothesis of vocal individuality. The similarity between ‘close’ up calls was greatest when the calls were within 0.5 minutes of each other, and declined progressively, up to a separation of 6.5 minutes, as the likelihood of both calls being from one whale declined, indicating individual bout-calling. Medium and high down (downwardly inflected) calls, associated with surface active groups (SAGs), and thought by other researchers to be produced by the focal female, were more similar within any given SAG than when compared across SAGs. This evidence strongly suggests that southern right whales produce individually distinctive vocalisations [chapter four]. / Thesis (PhD)--University of Pretoria, 2010. / Zoology and Entomology / unrestricted

Chez les baleines à bosse (Megaptera novaeangliae), le maintien des liens sociaux entre les femelles et leurs nouveau-nés implique différentes modalités sensorielles telles que l'ouïe, le toucher et la vision. Si la communication acoustique chez les mâles chanteurs de cette espèce a été largement étudiée, les sons sociaux, en particulier ceux produits par les femelles et leurs nouveau-nés, ont été peu reportés. Cette étude décrit les sons sociaux présents dans les enregistrements acoustiques axés sur les groupes mère-baleineau et discute des vocalisations produites par les femelles et les baleineaux dans les interactions mère-jeune. En considérant les sons les plus fréquents de ce répertoire vocal, une analyse centrée sur la détermination de la source des sons de bass fréquence produits par la mère a été effectuée et des analyses ont été réalisées pour mettre en évidence l'individualité de certaines vocalisations appartenant à la mère et à son petit. Une description du contexte comportemental de leur production vocale a été réalisée et parallèlement, les profils de plongée des mères et de leurs nouveau-nés ont été décrits. En outre, les femelles et leurs petits passent beaucoup de temps à la surface de l'eau. Les mères sont souvent statiques à la surface tandis que les baleineaux évoluent autour d'elles. Cette étude est également consacrée à la compréhension de leurs comportements de surface, en tenant compte des comportements initiés par les baleineaux. Des séries d’analyses ont été réalisées pour déterminer si les baleineaux présentaient des comportements de latéralisation par rapport à leur mère. Enfin, en utilisant la méthode de photogrammétrie, les tailles des femelles et des nouveau-nés ont été mesurées, ainsi que l'espace utilisée par les baleineaux autour de leur mère. / In humpback whales (Megaptera novaeangliae), maintaining social bonds between females and their newborns involves different sensory modalities such as hearing, touching and vision. While acoustic communication in male singers of this species has been extensively studied, social sounds, especially those produced by the females and their newborns have been poorly documented. This study describes the social sounds present in acoustic recordings focused on mother-calf groups and discusses the vocalizations used by females and calves in mother-offspring interactions. By considering the most frequent sounds from their vocal repertoire, an analysis focused on the determination of the source of the low-frequency sounds produced by the mother have been carried out and analyses were performed to investigate the individuality of some vocalizations belonging to the mothers and the calves. A description of the behavioural context of their vocal production was performed and the diving profiles of mother-calf pairs were described. Moreover, females with their calves spend a lot of time on the water surface. Mothers are often static at the surface while calves move around them. This study is also dedicated to the understanding of their surface behaviours, considering the behaviours initiated by calves. A series of analyses were carried out to determine whether calves exhibited lateralization behaviours in relation to their mothers. Finally, by using photogrammetry method, mother-calf lengths were measured, and calves spatial range around their mothers was investigated.

Titi monkeys have long been known for their complex vocal behaviour with numerous high- and low-pitched calls, which can be uttered singly or combined in more complex structures. However, up to date very little is known concerning the function, meaning and context-specific use of these vocal utterances, and virtually nothing is known about their vocalisations in the predation context. This thesis presents a detailed description of the form and function of the anti-predator behaviour of one species of titi monkeys, the black-fronted titi monkey (Callicebus nigrifrons), with a specific focus on their alarm call behaviour. A second aim was to determine the exact mechanisms of alarm calling behaviour, with an emphasis on production and comprehension. Data were collected from several habituated groups in the Caraça Reserve, Minas Gerais, Brazil. Results showed that, when detecting predator species, C nigrifrons produce sequences that initially contain two types of brief, high-pitched calls with distinct frequency contours. Further evidence suggested that some of these sequences are meaningful to conspecific receivers, by indicating the general predator class and location of threat. There were also indications that, within the terrestrial threats, additional information may be encoded by acoustic and compositional differences. Analyses of call order and number of calls per sequence suggested that callers may be able to convey information on both predator type and location. The black-fronted titi monkeys’ vocal system thus provides a further example of zoo-syntax, in which acoustically fixed units of a vocal repertoire are combined into higher order sequences that are meaningful to recipients. According to current definitions, this type of calling behaviour qualifies as functionally referential, by indicating general predator class, terrestrial predator type and location. As such, this is the first empirical demonstration of a sequence-based alarm call system that conveys information on both predator category and location.

<p>I use morphological, vocal, molecular, behavioural, ecological and distributional data to re-evaluate the systematics of three passerine bird groups, the <i>Mirafraassamica </i>complex (bush-larks), the genus <i>Seicercus</i> ("spectacled-warblers"; with emphasis on the the <i>S. burkii</i> complex) and the genus <i>Motacilla</i> (wagtails). Two new species are described: <i>Seicercus soror</i> and <i>Motacilla samveasnae</i>. I propose that the polytypic species <i>M. assamica</i> should be treated as four separate species: <i>M. assamica</i>, <i>M. affinis</i>, <i>M. microptera</i> and <i>M. marionae</i> (it is also remarked that the proper name of the latter is <i>M. erythrocephala</i>). That is primarily supported by vocalisations and mitochondrial DNA. The latter data set also suggests that <i>M. assamica</i> sensu lato is paraphyletic, since <i>M. erythroptera</i>, which is always treated as a separate species, is nested within the <i>M. assamica</i> complex. I propose that the polytypic species <i>S. burkii</i> comprises six sibling species. Some of these are found to breed sympatrically, although mainly or entirely segregated altitudinally. Mitochondrial DNA suggests that the <i>S. burkii</i> complex is non-monophyletic, and also that the divergence of the different taxa is much older than indicated by morphological and vocal data. According to the molecular phylogeny, both the genera <i>Seicercus</i> and its assumed sister genus <i>Phylloscopus</i> are paraphyletic. That is corroborated by independent data. The phylogenetic study of the genus <i>Motacilla</i> reveals incongruence between mitochondrial DNA, nuclear DNA and non-molecular data. I conclude that the nuclear gene tree reflects the organismal phylogeny more faithfully than the mitochondrial gene tree. The latter is likely to have been affected by introgressive hybridisation, possibly also stochastic lineage sorting. The most remarkable result that is strongly supported by both mitochondrial and nuclear DNA is that <i>M. flava</i> is non-monophyletic.</p>

I use morphological, vocal, molecular, behavioural, ecological and distributional data to re-evaluate the systematics of three passerine bird groups, the Mirafraassamica complex (bush-larks), the genus Seicercus ("spectacled-warblers"; with emphasis on the the S. burkii complex) and the genus Motacilla (wagtails). Two new species are described: Seicercus soror and Motacilla samveasnae. I propose that the polytypic species M. assamica should be treated as four separate species: M. assamica, M. affinis, M. microptera and M. marionae (it is also remarked that the proper name of the latter is M. erythrocephala). That is primarily supported by vocalisations and mitochondrial DNA. The latter data set also suggests that M. assamica sensu lato is paraphyletic, since M. erythroptera, which is always treated as a separate species, is nested within the M. assamica complex. I propose that the polytypic species S. burkii comprises six sibling species. Some of these are found to breed sympatrically, although mainly or entirely segregated altitudinally. Mitochondrial DNA suggests that the S. burkii complex is non-monophyletic, and also that the divergence of the different taxa is much older than indicated by morphological and vocal data. According to the molecular phylogeny, both the genera Seicercus and its assumed sister genus Phylloscopus are paraphyletic. That is corroborated by independent data. The phylogenetic study of the genus Motacilla reveals incongruence between mitochondrial DNA, nuclear DNA and non-molecular data. I conclude that the nuclear gene tree reflects the organismal phylogeny more faithfully than the mitochondrial gene tree. The latter is likely to have been affected by introgressive hybridisation, possibly also stochastic lineage sorting. The most remarkable result that is strongly supported by both mitochondrial and nuclear DNA is that M. flava is non-monophyletic.

La peur est ce qui permet de réagir à un stimulus aversif par une réponse de défense adaptée à la situation. Elle peut être générée par un ensemble de stimuli naturellement aversifs ou par des stimuli ayant acquis une valeur aversive par apprentissage associatif. Cette thèse a pour but d'étudier les caractéristiques et modifications de la réponse de peur à ces deux types de stimuli au cours de l'ontogenèse. Les études présentées ici utilisent un conditionnement de peur à l'odeur chez le rat qui associe une odeur à un stimulus aversif et permet d'induire très rapidement et durablement des mémoires de peur à l'odeur. La réponse de défense peut alors être étudiée à la fois envers l'odeur apprise et envers le stimulus naturellement aversif. Nous montrons en particulier que la réponse de peur à l'odeur apprise présente un décours temporel corrélé à la durée de l'intervalle de temps entre l'odeur et le stimulus aversif, permettant d'affirmer que les animaux mémorisent et estiment le temps, et ce dès les premiers âges étudiés, avant la maturation des structures cérébrales classiquement impliquées dans cette mémoire temporelle. Par ailleurs, nous nous sommes intéressés aux vocalisations ultrasonores émises en réponse au stimulus aversif et à leur modification au cours de l'ontogenèse. Nous avons mis en évidence deux types de vocalisations chez le raton, dont les caractéristiques et critères d'induction laissent présager un rôle différentiel qui reste à explorer. L'ensemble de ces travaux soulignent que, même si les réponses de défense du rat changent au cours du développement, la capacité à produire ces réponses de manière temporellement adaptée est observée dès le plus jeune âge / Fear allows individuals to react to an aversive stimulus by a defense response adapted to the situation. It can be triggered by naturally aversive stimuli or in response to stimuli that acquired an aversive valence through associative learning. This thesis investigated the characteristics and modifications of fear responses to these two types of stimuli throughout ontogeny. The studies presented here used olfactory fear conditioning in rat, in which an odor is paired with an aversive event and allows to rapidly induce long lasting odor fear memories. Defense responses can then be studied both to the learned odor and to the naturally aversive stimulus. We showed in particular that fear response to the learned odor presents a temporal pattern correlated with the duration of the time interval between the odor and the aversive event, showing that rats can learn about time and they do so at the youngest ages studied here, before the maturation of the brain structures classically involved in interval timing. We also studied the ultrasonic vocalizations emitted in response to the aversive stimulus and their changes throughout ontogeny. We described two types of vocalizations in pups that differ in their characteristics and emission context, suggesting they could have different functions, which needs further exploration. These thesis findings highlight that although the rat’s defense responses changes through ontogeny, the ability to produce temporally adapted responses occurs from the youngest age