Vocal communication as a function of differential rearing experiences inPan paniscus: A preliminary report

There is little evidence of vocal learning in nonhuman primates despite the well-documented abilities found in avian species. We describe the vocal repertoire of five bonobos (Pan paniscus), four of which live in a seminatural environment. The fifth subject, Kanzi, has been reared with humans during the course of language training. The data indicated that the four bonobos living in a seminatural environment exhibit a variety of species-typical vocalizations. In addition to producing all the species-typical vocalization, Kanzi produced four structurally unique vocalizations that were not heard among the other subjects. These data suggest that Kanzi has learned vocalizations that are novel due to his unique rearing experience. Discussion is focused on the flexibility of vocal communication and vocal comprehension inPan paniscus.     

Vocal ethology of the North Island kaka (Nestor meridionalis septentrionalis)

Abstract

We conducted acoustic and behavioural observations on wild New Zealand North Island kaka (Nestor meridionalis septentrionalis) to assess the behavioural context of their most common calls. We distinguished several call types by ear in the field and then quantitatively evaluated our call type classifications using spectrographic analyses. Next, we established the behavioural context of each call type during 500 h of field observations. We observed five distinctive call types that were clearly segregated in subsequent spectrographic analyses. Behavioural observations showed that each call type was generally associated with particular behaviours used by birds separated by different distances. Some call types were used by distantly‐separated solitary birds that were foraging or preening, while others were used mostly during copulation. Overall results indicate that kaka have a range of distinctive call‐types for communication under different spatial and social circumstances.     

Vocal communication in two lemming species (Lagurus lagurus and Eolagurus luteus)

The vocal repertoire of steppe (Lagurus lagurus Pallas, 1773) and yellow steppe (Eolagurus luteus Eversmann, 1840) lemmings consists of only one type of signal, namely, a squeak. The signal does, however, have considerable variability. The DFA standard procedure shows the significant differences in the parameters of squeaks between species and significant differences in squeak parameters between the sexes in steppe lemming but not in the yellow steppe lemming. The fundamental frequency of the smaller steppe lemming’s squeak is higher than that of the larger yellow steppe lemming, although the peak frequencies have comparable values. In addition, the steppe lemming displays a pronounced sexual dimorphism in vocalization parameters; the frequency characteristics of the signals of the smaller females have lower values, which are contrary to scaling laws, stating that smaller individuals tend to have higher fundamental and peak frequencies. The age-related variability in the signals of yellow steppe lemmings was also described. The fundamental frequency of their squeaks is higher than that of the adults, but the peak frequency of signals in young and adults is not distinguished, and its value is higher than theoretically calculated. Such deviation in signal frequency parameters from the optimum may be result of directed selection, indicating the high value of such signals in the acoustic communication of lemmings.     

Vocal discrimination of potential mates by female giant pandas (Ailuropoda melanoleuca)

In the current study, we used male giant panda (Ailuropoda melanoleuca) bleats in a habituation–discrimination paradigm to determine whether females discriminate between the vocalizations of different males. We found that females habituated to the bleats of a specific male showed a significant dishabituation when they were presented with bleats from a novel male. Further playbacks, in which we standardized the mean fundamental frequency (pitch) and amplitude modulation of male bleats, indicated that amplitude modulation is the key feature that females attend to when discriminating between male callers. Our results show that female giant pandas can discriminate between the vocalizations of potential mates and provide a platform for further studies investigating the functional role of caller identity in giant panda sexual communication.     

Vocal Signature in Wild Infant Chimpanzees

A large array of communication signals supports the fission/fusion social organization in chimpanzees, and among them the acoustic channel plays a large part because of their forest habitat. Adult vocalizations convey social and ecological information to their recipients allowing them to obtain cues about an ongoing event from calls only. In contrast to adult vocalizations, information encoded in infant calls had been hardly investigated. Studies mainly focused on vocal development. The present article aims at assessing the acoustic cues that support individual identity coding in infant chimpanzees. By analyzing recordings performed in the wild from seven 3‐year‐old infant chimpanzees, we showed that their calls support a well‐defined individual vocal signature relying on spectral cues. To assess the reliability of the signature across the calls of an individual, we defined two subsets of recordings on the basis of the characteristics of the frequency modulation (whimpers and screams) and showed that both call types present a reliable vocal signature. Early vocal signature may allow the mother and other individuals in the group to identify the infant caller when visual contact is broken. Chimpanzee mothers may have developed abilities to cope with changing vocal signatures while their infant, still vulnerable, gains in independence in close habitat. Am. J. Primatol. 75:324‐332, 2013. © 2012 Wiley Periodicals, Inc.     

Vocal cues to male androgen levels in giant pandas

Little is known about the potential of non-human mammal vocalizations to signal information on the hormonal status of the caller. In the current study, we used endocrine data and acoustic analyses to determine whether male giant panda bleats provide reliable information about the caller''s current androgen levels. Our results revealed significant relationships between acoustic features of male giant panda bleats and the caller''s faecal androgen metabolite concentrations. To our knowledge, this constitutes the first demonstration that the acoustic structure of a non-human mammal call has the potential to yield information about the caller''s current androgen levels. We go on to discuss the anatomical basis for our findings and the potential functional relevance of signalling information on male androgen levels in giant panda sexual communication.     

Vocal cooperation between the sexes in Little Spotted Kiwi Apteryx owenii

Sexual call dimorphism in birds is usually associated with sexual size dimorphism. Departures from this relationship can be used to infer call function, but research into inter‐sexual call differences, as with song function in general, has been restricted by a bias towards male passerines. The nocturnal and flightless New Zealand kiwi (Apterygidae) are acoustically similar but taxonomically and ecologically very different from other birds, so provide a contrast in exploring avian call function and evolution. However, kiwi acoustic ecology is poorly understood, with the calls of only one of the five kiwi species spectrally described, and acoustic differences between the sexes virtually unknown. We conducted the first bioacoustic study of Little Spotted Kiwi Apteryx owenii, and assessed sexual call dimorphism in this species. There were significant inter‐sexual differences in call temporal and frequency characteristics that were not related to size dimorphism. Contribution to duets and variation in temporal structure with call context also differed between the sexes. We suggest that these differences indicate divergent call function, with male calls more suited for territory defence, and female calls for pair contact. There was a striking lack of overlap in the frequency spectrum distributions of male and female calls, which was also unrelated to size and was further emphasized by the presence of formants in female calls. We propose that this provides evidence for inter‐sexual acoustic cooperation in call frequency, of a type which to our knowledge has not previously been described in birds. This may result from selection for enhanced joint resource defence in kiwi.     

Maternal presence influences vocal development in the Japanese quail (Coturnix c. japonica)

Social influences on vocal development of young birds have been widely studied in oscine songbirds who learn to sing by vocal imitation of conspecifics, mainly male adults. In contrast, vocal development of non-vocal learners such as Galliformes is considered as being under strong genetic influence and independent of the social environment. In this study, we investigated the role of the mother on the vocal development of young Japanese quail (Coturnix coturnix japonica). We compared the vocal development of mothered and non-mothered chicks during the first 21 days of life. We analysed the structural changes of two vocalisations: a) the rally call, emitted during long-distance communication and in stressful situations, b) the contact call, emitted during short-distance communication when chicks are in visual and/or auditory contact with congeners. We showed that temporal and spectral structures of the two types of calls changed during development and differed between mothered and non-mothered chicks. These results demonstrate that maternal presence influences the vocal development of the young in the Japanese quail. Even if the adaptive value of such changes was not assessed, these results highlight that plasticity of vocalisations in species considered as non-vocal learners has been underestimated.     

Vocal coordination of troop movement among white-faced capuchin monkeys,Cebus capucinus

Coordinated travel by social groups is well documented, often with evidence that cognitive spatial maps are employed. Yet the mechanisms by which movement decisions are made and implemented within social groups are poorly known. In a field study of white-faced capuchin monkeys in Costa Rica it was demonstrated that a specific call, the “trill,” is used by adults in the initiation and directing of troop movement. The trills of subadults were restricted to vocal exchanges with other subadults. Continuous vocal recordings were collected of the vocalizations of the 14 members of the study troop. A cumulative 33.7 h of continuous samples and 1,892 sonagrams were analyzed. In addition to vocalizations clearly associated with alarm, distress, or agonistic contexts, two distinct call types were identified, trills and huhs. Age-sex classes differed in the rate at which both types of calls were produced in different spatial positions within the troop. Adult females and males produced higher rates of trills when in the leading edge compared to all other spatial positions in a traveling troop. Trills at the edge of a stationary troop represented 36 “successful” and 3 “unsuccessful” start attempts; the troop usually moved in the trajectory predicted by a trilling adult's location on the troop periphery within 10 min of the initiation of trilling. Adults also altered the trajectory of traveling troops by trilling at the side and back of the troop (10 “successful” and 4 “unsuccessful” attempts). Huh vocalizations were most predictably produced when a capuchin is in a dense fruit patch. These results emphasize the role vocalizations serve in the coordination and trajectory of group movement in nonhuman primates, especially those populations that are arboreal or in which visual contact is otherwise impeded. © 1993 Wiley-Liss, Inc.

1 This article is a US Government work and, as such, is in the public domain in the United States of America.

     

Female Social Feedback Reveals Non-imitative Mechanisms of Vocal Learning in Zebra Finches

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Vocal copying of individually distinctive signature whistles in bottlenose dolphins

Vocal learning is relatively common in birds but less so in mammals. Sexual selection and individual or group recognition have been identified as major forces in its evolution. While important in the development of vocal displays, vocal learning also allows signal copying in social interactions. Such copying can function in addressing or labelling selected conspecifics. Most examples of addressing in non-humans come from bird song, where matching occurs in an aggressive context. However, in other animals, addressing with learned signals is very much an affiliative signal. We studied the function of vocal copying in a mammal that shows vocal learning as well as complex cognitive and social behaviour, the bottlenose dolphin (Tursiops truncatus). Copying occurred almost exclusively between close associates such as mother–calf pairs and male alliances during separation and was not followed by aggression. All copies were clearly recognizable as such because copiers consistently modified some acoustic parameters of a signal when copying it. We found no evidence for the use of copying in aggression or deception. This use of vocal copying is similar to its use in human language, where the maintenance of social bonds appears to be more important than the immediate defence of resources.     

网络分析法在动物声音通讯及生物声学研究中的应用与前景

动物社会网络分析法(animal social network analysis,ASNA)是一套用于研究动物社会性、量化个体间各种社会关系、揭示个体行为与社会结构动态之间联系的工具,被广泛应用于多种动物类群的行为学研究。该分析方法所提供的一系列指标也非常适用于探究动物的声音交流及鸣声结构。在此,本文首先简要介绍了网络分析法的基本概念及一些常用的指标;然后基于野外和室内研究实例,阐述了如何利用ASNA建立声音通讯网络、量化声音交流,以及将ASNA与被动声学监测技术相结合的应用前景;随后探讨了ASNA在分析鸣声相似性及鸣声地理变异中的优势;最后概述了ASNA在解析鸣声结构和句法规则中的应用。ASNA为研究动物通讯网络以及声音信号的适应性进化提供了新的视角和新的思路。     

Wild Birds Learn Songs from Experimental Vocal Tutors

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Importance of sleep for avian vocal communication

Sleep is one of the few truly ubiquitous animal behaviours, and though many animals spend enormous periods of time asleep, we have only begun to understand the consequences of sleep disturbances. In humans, sleep is crucial for effective communication. Birds are classic models for understanding the evolution and mechanisms of human language and speech. Bird vocalizations are remarkably diverse, critical, fitness-related behaviours, and the way sleep affects vocalizations is likely similarly varied. However, research on the effects of sleep disturbances on avian vocalizations is shockingly scarce. Consequently, there is a critical gap in our understanding of the extent to which sleep disturbances disrupt communication. Here, we argue that sleep disturbances are likely to affect all birds'' vocal performance by interfering with motivation, memory consolidation and vocal maintenance. Further, we suggest that quality sleep is likely essential when learning new vocalizations and that sleep disturbances will have especially strong effects on learned vocalizations. Finally, we advocate for future research to address gaps in our understanding of how sleep influences vocal learning and performance in birds.