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Vocal repertoire of wild Andean night monkeys (Aotus lemurinus) in an Andean forest in Colombia
Abstract
Vocal communication is particularly important for nocturnal species as well as those living in dense forests, where visual abilities can be somewhat constrained. The Andean night monkey (Aotus lemurinus) is a nocturnal American primate living in mountain forests in the Northern Andes with scant information on its behavior and ecology. The main goal of this study is to describe the vocal repertoire of a group of wild Andean night monkeys and compare it with earlier bioacoustics studies on the only nocturnal platyrrhines. We recorded the vocal behavior of a group of night monkeys living in the eastern Andes of Colombia between August and December 2019. Based on an auditory and a visual inspection of the vocal records, and through a quantitative analysis of the acoustic parameters of the vocalizations, we were able to identify five different calls emitted by the Andean night monkey. Four of these calls are stereotyped while the fifth vocalization (Squeak) is more variable, having different forms. Additionally, one call (Acetate) was found to be unique to this species. The result of this study contributes to the scant information on the ecology and behavior of the Andean night monkey and sets baseline information on the vocal behavior of night monkeys that may be used in future studies on communication of these and other nocturnal primates.
Anointing occurs when animals rub substances on their own or other individuals’ bodies for various purposes. Although this behavior has been described in several species, it has only been observed in captivity in night monkeys. We present the first report of anointing (self and allo-anointing) in wild night monkeys, occurring specifically in the Caribbean night monkey (Aotus griseimembra Elliot, 1912). The event involved three of the five individuals in the group writhing, closing their eyes, and salivating. Anointing in wild night monkeys may be related to auto-medication or may serve as an insect repellent, or both, considering the chemical characteristics of millipedes.
Most primates live in lowland ecosystems; however, some species have been particularly successful at colonizing higher altitudes, such as night monkeys (genus Aotus). Studies of the ecology of night monkeys in tropical forests are numerous, but behavioral data are limited due to the challenges associated with their nocturnal habits. Although Andean night monkeys (A. lemurinus) live in mountain forests >1000 m.a.s.l. and Caribbean night monkeys (A. griseimembra) live in rainforests <1000 m.a.s.l., they are found at similar tropical latitudes. Between 2018 and 2019, we followed three groups of A. lemurinus and one group of A. griseimembra at three sites in Colombia and recorded data on their ecology and behavior. Although they live at different altitudes, the two species had similar activity patterns and diet, investing approximately half of the night in resting (48%), and feeding primarily on fruits. We found differences among groups in the time invested in feeding on flowers, their home range, and distance traveled per night. These differences may be related to the unique characteristics of each study site and differences in resource availability and floristic composition of forests at different altitudes. Although the most important families in their diet were Moraceae and Urticaceae, highland groups also fed frequently on a large number of Melastomataceae and Rubiaceae trees. This research suggests these two nocturnal primates, living in contrasting environments, use similar strategies to cope with the challenges of being active at night in tropical forests.
Primates use different types of vocalizations in a variety of contexts. Some of the most studied types have been the long distance or loud calls. These vocalizations have been associated with mate defense, mate attraction, and resource defense, and it is plausible that sexual selection has played an important role in their evolution. Focusing on identified individuals of known sex and age, we evaluated the sexual dimorphism in a type of loud calls (hoots) in a population of wild owl monkeys (Aotus azarae) in Argentina. We found evidence of sexual dimorphism in call structure, with females and males only emitting one type of call, each differing in dominant frequency and Shannon entropy. In addition, both age-related and sex-specific differences in call usage were also apparent in response to the removal of one group member. Future acoustic data will allow us to assess if there are individual characteristics and if the structure of hoot calls presents differences in relation to the social condition of owl monkeys or specific sex responses to variants of hoot calls’ traits. This will provide deeper insights into the evolution of vocal mechanisms regulating pair bonding and mate choice strategies in this and other primate species.
Quantitative acoustic analysis has been used to decipher individual differences, population structure, and taxonomic diversity in numerous primate species. We previously described three distinct call types in wild Aotus nigriceps, and now assess acoustic differences in two of these call types between social groups and spatially distinct populations. Acoustic parameters for both analyzed call types exhibited significant variability between groups. Similarly, geographically distant field sites were acoustically distinct from one another. Several groups also used a variation of a common call: a triplet Ch Ch instead of a duplicate. Other groups made use of ultrasonic frequencies which have not previously been reported in Aotus. Our results suggest that Aotus nigriceps exhibits substantial acoustic variability across sites that could potentially be useful for taxonomic classification, although additional geographically distant populations still need to be sampled. The possibility of individual signatures also exists and will require recording vocalizations from known individuals.
The Tropical Andes Hotspot is a high conservation priority. A high proportion of the northern Colombian Andes has been deforested affecting its biological diversity, including primates, for which there are information gaps that hinder the formulation of conservation strategies. We conducted a bibliographic search on studies of non-human primates developed in the northern portion of the Central and Western cordilleras, to generate a baseline facilitating the priorization of information generation and guidelines to formulate research projects at the regional level. We updated the species list for the fourth departments evaluated, recording a total of 13 species (Antioquia: 13; Caldas: 6; Risaralda: 5; Quindío: 2). We compiled a total of 120 studies which evidenced a greater research effort in topics related to ecology, genetics, and veterinary medicine, as well as a reduced emphasis in ethnobiological research. Saguinus leucopus and Alouatta seniculus were the most studied species, contrasting with the scarce information generated for threatened species such as Ateles fusciceps, Ateles hybridus, three especies of Aotus (lemurinus, zonalis, griseimembra), Alouatta palliata, Cebus versicolor, Lagothrix lagotricha, Saguinus geoffroyi and Saguinus oedipus.
Significance
Understanding how human speech evolved requires investigating how our closest extant relatives—nonhuman primates—use and produce their vocalizations. However, some believe that primate vocalizations are driven purely by internal states such as arousal and thus have little or no relationship with human speech. We show that, in marmoset monkeys, vocal production varies systematically as a function of social distance and—via measures of heart rate—with arousal levels. However, arousal is not inextricably linked with primate vocal production. Rather, it interacts in complex ways with external cues, revealing the interplay between communication and energetic demands.
We review Seewave, new software for analysing and synthesizing sounds. Seewave is free and works on a wide variety of operating systems as an extension of the R operating environment. Its current 67 functions allow the user to achieve time, amplitude and frequency analyses, to estimate quantitative differences between sounds, and to generate new sounds for playback experiments. Thanks to its implementation in the R environment, Seewave is fully modular. All functions can be combined for complex data acquisition and graphical output, they can be part of important scripts for batch processing and they can be modified ad libitum. New functions can also be written, making Seewave a truly open-source tool.
Social factors play a key role in the structuring of vocal repertoires at the individual level, notably in non-human primates. Some authors suggested that, at the species level too, social life may have driven the evolution of communicative complexity, but this has rarely been empirically tested. Here, we use a comparative approach to address this issue. We investigated vocal variability, at both the call type and the repertoire levels, in three forest-dwelling species of Cercopithecinae presenting striking differences in their social systems, in terms of social organization as well as social structure. We collected female call recordings from twelve De Brazza's monkeys (Cercopithecus neglectus), six Campbell's monkeys (Cercopithecus campbelli) and seven red-capped mangabeys (Cercocebus torquatus) housed in similar conditions. First, we noted that the level of acoustic variability and individual distinctiveness found in several call types was related to their importance in social functioning. Contact calls, essential to intra-group cohesion, were the most individually distinctive regardless of the species, while threat calls were more structurally variable in mangabeys, the most "despotic" of our three species. Second, we found a parallel between the degree of complexity of the species' social structure and the size, diversity, and usage of its vocal repertoire. Mangabeys (most complex social structure) called twice as often as guenons and displayed the largest and most complex repertoire. De Brazza's monkeys (simplest social structure) displayed the smallest and simplest repertoire. Campbell's monkeys displayed an intermediate pattern. Providing evidence of higher levels of vocal variability in species presenting a more complex social system, our results are in line with the theory of a social-vocal coevolution of communicative abilities, opening new perspectives for comparative research on the evolution of communication systems in different animal taxa.
Upon encountering predators, many animals produce specific vocalisations that alert others and sometimes dissuade the predators from hunting. Callicebus monkeys are known for their large vocal repertoire, but little is known about the function and meaning of most call types. We recorded a large number of natural predator responses from five different groups of black-fronted titi monkeys in their Atlantic forest habitat in South Eastern Brazil. When detecting predatory threats, adult group members responded with call sequences that initially consisted of two brief, high-pitched calls with distinct frequency contours. Call A was mainly given to raptors but also to predatory capuchin monkeys and other threats within the canopy, while call B was given to predatory or non-predatory disturbances on the ground. In later parts of the sequences, we also recorded a high-pitched unmodulated call C and various low-pitched loud calls. Results therefore suggest that calls A and B provide listeners with rapid and reliable information about the general classes of danger experienced by the caller, while obtaining more specific information through other call types and combinations and behavioural responses. We discuss these findings in relation to current evolutionary theory of primate communication.
In Colombia, there are approximately 27-31 primate species, including at least five endemic ones and a high proportion of threatened species. Differences in these primates' distribution, abundance, ecology, and charisma, among many other things, have led to large variation in the amount and nature of investigations performed on the different species. Basic information on each native primate species is necessary to build adequate conservation plans; therefore, knowledge of the quantity and type of information available on each species can be helpful to identify possible research gaps. Based on publications from 1900 to 2008 on 25 primate species present in Colombia, we evaluated primate research in this country in terms of quantity, type, and topics of investigation. Additionally, we comparatively assessed the role of Colombian primatology within all scientific production on primate species present in this country. Our analyses indicate that in Colombia, primate research has developed mainly in the field-work area, with studies focused primarily on ecology and behavior. Investigations of topics such as karyology, anatomy, and physiology are very limited, and molecular biology is understudied compared to research on this subject in other countries. Captive studies are also comparatively scarce. Our analyses also suggest that those species distributed in areas where research stations are located have been the focus of a greater proportion of investigations. A few study sites (PNN La Macarena, Rio Peneya Station, PNN Tinigua, and Caparu Biological Station) stand out as primate research "hot-spots" within Colombia; however, field work in these stations is frequently jeopardized by the constant threat imposed by revolutionary armed forces in the rural and forested parts of Colombia.
Quantitative evaluations of vocalizations of nocturnally active owl monkeys (Aotus species) have been attempted only twice. Andrew (1963) identified four call types in 2 captive individuals. Moynihan (1964) identified six call types in a quasi-wild condition.
We studied vocalizations of 16 owl monkeys (Aotus azarae) reared at the Kyoto University's Primate Research Institute facility, under captive conditions. We could distinguish six categories of acoustic call types. These were, moan, long scream, gulp, low trill, short scream and sneeze grunt. During the recording period, low trill was the most frequent and sneeze grunt was the least frequent call. Sound spectrograms of six call types recorded are provided.
IntroductionPsychophysiological Determinants of Emotional Speech PatternsIntra and Inter-Emotion Pattering of Acoustic ParametersConclusion
AcknowledgementsReferences
Researchers studying nonhuman primate vocal repertoires suggest that convergent environmental, social, and motivational factors
account for intra- and interspecific vocal variation. We provide a detailed overview of the vocal repertoire of white-faced
capuchins, including acoustic analyses and contextual information of vocal production and vocal usage by different age-sex
classes in social interactions. The repertoire is a mixture of graded and discrete vocalizations. In addition, there is general
support for structural variation in vocalizations with changes in arousal level. We also identified several combined vocalizations,
which might represent variable underlying motivations. Lastly, by including data on the social contexts and production of
vocalizations by different age-sex classes, we provide preliminary information about the function of vocalizations in social
interactions for individuals of different rank, age, and sex. Future studies are necessary to explore the function of combined
vocalizations and how the social function of vocalizations relate to their acoustic structure, because social use of vocalizations
may play an important role in shaping vocal evolution.
The acoustic properties of the environment influence sound propagation. Many previous studies examined whether various species of anurans, birds and mammals adjust usage and/or structure of their vocal signals to limit degradation during propagation in this environment (“acoustic adaptation hypothesis”). The present review examines how widespread such adaptations actually are across taxa. First, evidence for environment-related adjustments in usage of vocal signals is collected from studies in birds and other vertebrates (i.e., anurans and mammals). Second, a meta-analysis conducted by Boncoraglio & Saino (2007) on the influences of the environment on the acoustic structure of avian vocalisations is taken as a reference, and results from additional studies in birds are reviewed and compared to its conclusions. Finally, evidence from similar studies conducted in anurans and mammals is collected and discussed. Concerning the usage of vocal signals, evidence of environment-related adaptations in the few studies found was more widespread in anurans and mammals than in birds. Regarding structure of vocal signals, evidence from additional studies in birds did not completely confirm results of the meta-analysis of Boncoraglio & Saino (2007). Pooling all bird studies together presented minimum frequency, frequency modulations and frequency range as acoustic variables most often adjusted to the environment, in contrast to temporal features, repetition rate and maximum frequency. The few studies conducted in anurans and mammals did not allow the identification of specific acoustic variables that typically show environment-related variations. Overall, evidence for the acoustic adaptation hypothesis was not as widespread as expected across taxa. The different aspects of vocal behaviour adapted to environmental conditions varied according to the species and local habitats. Environment-related adjustments in structure of vocal signals seem to be constrained by call function in anurans and mammals. This effect was not examined in birds, but vocal learning does not appear to be a pre-requisite to environment-related adjustment in this group.
Primates are intensely social and exhibit extreme variation in social structure, making them particularly well suited for uncovering evolutionary connections between sociality and vocal complexity. Although comparative studies find a correlation between social and vocal complexity, the function of large vocal repertoires in more complex societies remains unclear. We compared the vocal complexity found in primates to both mammals in general and human language in particular and found that non-human primates are not unusual in the complexity of their vocal repertoires. To better understand the function of vocal complexity within primates, we compared two closely related primates (chacma baboons and geladas) that differ in their ecology and social structures. A key difference is that gelada males form long-term bonds with the 2-12 females in their harem-like reproductive unit, while chacma males primarily form temporary consortships with females. We identified homologous and non-homologous calls and related the use of the derived non-homologous calls to specific social situations. We found that the socially complex (but ecologically simple) geladas have larger vocal repertoires. Derived vocalizations of geladas were primarily used by leader males in affiliative interactions with 'their' females. The derived calls were frequently used following fights within the unit suggesting that maintaining cross-sex bonds within a reproductive unit contributed to this instance of evolved vocal complexity. Thus, our comparison highlights the utility of using closely related species to better understand the function of vocal complexity.
In this article, we present FactoMineR an R package dedicated to multivariate data analysis. The main features of this package is the possibility to take into account different types of variables (quantitative or categorical), different types of structure on the data (a partition on the variables, a hierarchy on the variables, a partition on the individuals) and finally supplementary information (supplementary individuals and variables). Moreover, the dimensions issued from the different exploratory data analyses can be automatically described by quantitative and/or categorical variables. Numerous graphics are also available with various options. Finally, a graphical user interface is implemented within the Rcmdr environment in order to propose an user friendly package.
Primates show activity patterns ranging from nocturnality to diurnality, with a few species showing activity both during day and night. Among anthropoids (monkeys, apes and humans), nocturnality is only present in the Central and South American owl monkey genus Aotus. Unlike other tropical Aotus species, the Azara's owl monkeys (A. azarai) of the subtropics have switched their activity pattern from strict nocturnality to one that also includes regular diurnal activity. Harsher climate, food availability, and the lack of predators or diurnal competitors, have all been proposed as factors favoring evolutionary switches in primate activity patterns. However, the observational nature of most field studies has limited an understanding of the mechanisms responsible for this switch in activity patterns. The goal of our study was to evaluate the hypothesis that masking, namely the stimulatory and/or inhibitory/disinhibitory effects of environmental factors on synchronized circadian locomotor activity, is a key determinant of the unusual activity pattern of Azara's owl monkeys. We use continuous long-term (6-18 months) 5-min-binned activity records obtained with actimeter collars fitted to wild owl monkeys (n = 10 individuals) to show that this different pattern results from strong masking of activity by the inhibiting and enhancing effects of ambient luminance and temperature. Conclusive evidence for the direct masking effect of light is provided by data showing that locomotor activity was almost completely inhibited when moonlight was shadowed during three lunar eclipses. Temperature also negatively masked locomotor activity, and this masking was manifested even under optimal light conditions. Our results highlight the importance of the masking of circadian rhythmicity as a determinant of nocturnality in wild owl monkeys and suggest that the stimulatory effects of dim light in nocturnal primates may have been selected as an adaptive response to moonlight. Furthermore, our data indicate that changes in sensitivity to specific environmental stimuli may have been an essential key for evolutionary switches between diurnal and nocturnal habits in primates.
Vocalizations of titi monkeys were recorded from 6 groups at two sites in the Ilanos of Colombia during 8 months of study. Frequency and temporal measurements from spectrograms of recordings, and differences in their patterns of use, were used to characterize call types. Animals repeat calls to form phrases, and combine phrases to form sequences. The six sequence types, defined by different transition probabilities between phrases, varied in proportion in different contexts. To examine the effect of order of phrases on response, I played back artificially constructed sequences to subject groups. I discuss hierarchical and sequential mechanisms as generators of vocal sequences, and draw comparisons with models of human language.
This paper examines the importance of vision in the lives of nocturnal primates in comparison to diurnal and cathemeral species. Vision is the major sense in all primates and there is evidence that the eyesight of nocturnal species is more acute and variable than has previously been recognized. Case studies of the behaviour of a galago and a loris in open woodland habitats in relation to ambient light show that Galago moholi males are more likely to travel between clumps of vegetation along the ground when the moon is up, and during periods of twilight, whereas they retreat to more continuous vegetation and travel less when the moon sets. This is interpreted as a strategy for avoiding predators that hunt on the ground when it is dark. The travel distances of Loris lydekkerianus are not affected by moonlight but this species reduces its choice of food items from more mobile prey to mainly ants when the moon sets, indicating the importance of light when searching for high-energy supplements to its staple diet. Evidence is presented for the first time to indicate key aspects of nocturnal vision that would benefit from further research. It is suggested that the light and dark facial markings of many species convey information about species and individual identity when animals approach each other at night. Differences in the colour of the reflective eye-shine, and behavioural responses displayed when exposed to white torchlight, point to different kinds of nocturnal vision that are suited to each niche, including the possibility of some degree of colour discrimination. The ability of even specialist nocturnal species to see well in broad daylight demonstrates an inherent flexibility that would enable movement into diurnal niches. The major differences in the sensitivity and perceptual anatomy of diurnal lemurs compared to diurnal anthropoids, and the emergence of cathemerality in lemurs, is interpreted as a reflection of evolution from different ancestral stocks in very different ecosystems, and not a recent shift towards diurnality due to human disturbance.
Understanding the rules that link communication and social behaviour is an essential prerequisite for discerning how a communication system as complex as human language might have evolved. The comparative method offers a powerful tool for investigating the nature of these rules, since it provides a means to examine relationships between changes in communication abilities and changes in key aspects of social behaviour over evolutionary time. Here we present empirical evidence from phylogenetically controlled analyses indicating that evolutionary increases in the size of the vocal repertoire among non-human primate species were associated with increases in both group size and time spent grooming (our measure of extent of social bonding).
Loud calls play an important function in regulating the use of space and structuring social groups and mating systems in a wide range of taxa. In pair-living territorial animals, where encounters with neighbors and solitary conspecifics are common, these calls are mainly associated with resource defense or mate guarding behaviors. Owl monkeys (Aotus azarae) live in groups of one pair of reproducing adults and 1–4 younger, non-reproducing individuals. Both sexes disperse when they are around 3 years of age; they become solitary floaters who compete to replace same-sex adults from other groups. Here, we examined the behavioral responses of Azara's owl monkey pairs toward calls of unpaired and unfamiliar males and females to better understand if the competition between floaters and groups is in relationship to the defense of their territory, their mates, or both. We collected behavioral data from six groups, before, during, and after the playing back of unfamiliar male and female loud calls and of a control stimulus at the center and border of their home ranges. Overall, our results showed that the playback location did not elicit differential responses in the monkeys and that both sexes were more reactive to male than female unfamiliar calls, as evidenced by higher rates of sociosexual and vocal responses, movement toward the playback, and intergroup encounters during and after the experiments. Our study indicates that paired male and female owl monkeys mainly defend their partners toward intruders and emphasizes the need of including the role of sexual competition on both sexes in models about the evolution of pair-living social organizations and sexual monogamy mating systems.
This is the first in a series of papers on some behavior patterns of New World monkeys. The main emphasis of these papers will be comparative. Special attention will be paid to social signal patterns (including hostile and sexual signals) and other patterns that differ significantly in the various species. It is hoped that analyses of these patterns may throw some light on the evolution of the group as a whole.
Primate Hearing and Communication provides unique insights into the evolution of hearing and communication in primates, including humans.
· Introduction to Primate Hearing and Communication
Marissa A. Ramsier and Rolf M. Quam
· The Primate Peripheral Auditory System and the Evolution of Primate Hearing
SirpaNummela
· Primate Audition: Reception, Perception, and Ecology
Marissa A. Ramsier and Josef P. Rauschecker
· Primate Habitat Acoustics
Charles H. Brown and Peter M. Waser
· Evolutionary Origins of Primate Vocal Communication: Diversity, Flexibility, and Complexity of Vocalizations in Basal Primates
Elke Zimmermann
· Vocal Communication in Family-Living and Pair-Bonded Primates
Charles T. Snowdon
· The Primate Roots of Human Language
Klaus Zuberbühler
· Evolution of Hearing and Language in Fossil Hominins
Rolf M. Quam, Ignacio Martínez, Manuel Rosa, and Juan Luis Arsuaga
Rolf M. Quam is Associate Professor in the Department of Anthropology, Binghamton University (SUNY), Binghamton, NY
Marissa A. Ramsier is Assistant Professor in the Department of Anthropology, Humboldt State University, Arcata, CA
Richard R. Fay is Distinguished Research Professor of Psychology at Loyola University of Chicago
Arthur N. Popper is Professor Emeritus and Research Professor in the Department of Biology at the University of Maryland, College Park
Communication consists of the transmission of information from one animal to another. Information is encoded by one individual into a signal. When received by another animal, this information undergoes decoding, while still retaining a specifiable relationship to the encoded information. The relationship is sometimes deterministic, sometimes only probabilistic. During such encoding and decoding, the carrier of the information and the format of the information undergo many transformations. Starting with the original designatum or referent, information passes through a series of steps internal to the signaling animal before effecting a change of state of the signaling organ. A signal is then propagated in a medium. Further steps follow, from transmitted signal to receptor organs of a recipient, from sensory to central processing, and eventually to a recipient’s overt or covert response.
1. It is not possible to treat mammalian vocalisations and facial expressions in terms of a drive model. They can be best described as basically dependent on
This study describes selection derived from habitat acoustics on the physical structure of avian sounds. Sound propagation tests were made in forest, edge, and grassland habitats in Panama to quantify pure tone and random noise band sound transmission levels. The sounds of bird species in each habitat were analyzed to determine the emphasized frequency, frequency range, and sound type (whether pure tonelike or highly modulated). Forest habitats differ from grass and edge in that a narrow range of frequencies (1,585-2,500 Hz) has lower sound attenuation than lower or higher frequencies. Attenuation increases rapidly above 2,500 Hz. Bird sounds from species occurring at the lower forest levels were found to be predominantly pure tonelike with a frequency emphasized averaging 2,200 Hz, conforming to the predictions based on sound propagation tests. The edge habitat is characterized by a wide range of frequencies having a generally similar attenuation rate. Pure tone and random noise band sounds did not diffe...
This paper describes a concept, not altogether new but largely neglected, that should lead to a greater understanding of the information contained in certain classes of vocal communication signals of birds and mammals. The concept is based on empirical data, first pointed out by Collias (1960, p. 382), showing that natural selection has resulted in the structural convergence of many animal sounds used in "hostile" and "friendly" contexts. Simply stated, birds and mammals use harsh, relatively low-frequency sounds when hostile and higherfrequency, more pure tonelike sounds when frightened, appeasing, or approaching in a friendly manner. Thus, there appears to be a general relationship between the physical structures of sounds and the motivation underlying their use. I hope to develop the idea that this relationship has had a far greater influence on the evolution of animal communication systems than has hitherto been discussed. I will discuss the idea that there exist motivation-structural rules (MS) governing the physical structure of close contact sounds in animal communication systems. The greatest value of the MS concept is that it provides the opportunity to compare the evolution of vocal communication in any species against an abstract concept. The adaptive nature of communication systems against varying backgrounds of environment, social system, and competition will appear in clear relief.
Three experiments were performed attempting to establish the validity of vocal measures as an indicator of the immediate response to pain in domestic piglets. Vocalisations were measured while piglets were subjected to the routine farm practice of castration without anaesthetic, or restrained identically but not castrated (i.e., sham-castrated). In Experiment 1 we measured how calling changed during the different stages of the procedure, and in Experiments 2 and 3 we measured the effect of different restraint techniques. Piglets that were castrated produced significantly more high frequency calls (>1000 Hz) than sham castrates in all three experiments. In Experiment 1, we found the greatest differences between the castrated and sham piglets during the severing of the spermatic cords (1.0 high calls/s vs. 0.3 calls/s, P
There is general agreement that in non-human primates, the emotional state of a caller is reflected in the vocal structure. But only few studies describe call features characterizing such correlates. This is mainly due to the fact that it is difficult to identify the emotional state of a caller. In the present study, we analysed calls from a study (Jürgens, 1979) in which squirrel monkeys had been given the opportunity to control vocalization-eliciting brain stimulation. In this way, the aversive or hedonistic quality of the emotional state underlying the production of specific calls could be determined. 758 of the recorded calls, representing 8 different call types, given by 25 subjects, were analysed in order to find out whether differences in the degree of aversion are reflected by specific acoustic parameters. It was found that an increase in aversion is parallelled, depending upon the call type, by an upward shift of maximal energy in the power spectrum, an increase in frequency range and/or an increase in the ratio of nonharmonic to harmonic energy.
Makes a quantitative comparison of the frequency of usage of vocal signals in the chimpanzee and the gorilla and discusses the emphasis in these species on graded vocal sounds. Data are taken from the author's 2,656 tape-recorded vocalizations of individual chimpanzees and are compared with D. Fossey's (1972) data on a similar sample of mountain gorilla vocalizations. The findings are used to relate vocal behavior to social organization in the two species. A review is made of human categorical perceptual processing of graded sounds occurring in normal speech. A possible model is derived for analyzing vocal perception in higher nonhuman primates which make frequent use of graded vocalizations in their social behavior. (3 p ref) (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Abstract The aim of this study was to investigate how information about the affective state is expressed in vocalizations. Alarm calls can serve as model systems with which to study this general question. Therefore, we examined the information content of terrestrial predator alarm calls of redfronted lemurs (Eulemur fulvus rufus), group-living Malagasy primates. Redfronted lemurs give specific alarm calls only towards raptors, whereas calls given in response to terrestrial predators (woofs) are also used in other situations characterized by high arousal. Woofs may therefore have the potential to express the perceived risk of a given threat. In order to examine whether different levels of arousal are expressed in call structure, we analysed woofs given during inter-group encounters or in response to playbacks of a barking dog, assuming that animals engaged in inter-group encounters experience higher arousal than during the playbacks of dog barks. A multivariate acoustic analysis revealed that calls given during group encounters were characterized by higher frequencies than calls given in response to playbacks of dog barks. In order to examine whether this change in call structure is salient to conspecifics, we conducted playback experiments with woofs, modified in either amplitude or frequencies. Playbacks of calls with increased frequency or amplitude elicited a longer orienting response, suggesting that different levels of arousal are expressed in call structure and provide meaningful information for listeners. In conclusion, the results of our study indicate that the information about the sender's affective state is expressed in the structure of vocalizations.
In order to remain stable, dispersed social groups have to solve two fundamental problems: the coordination of movement and cohesiveness within a group and the spacing between the groups. Here, we investigate mechanisms involved in intra-group coordination and inter-group spacing using the golden brown mouse lemur, Microcebus ravelobensis, as a model for a nocturnal, solitary foraging mammal with a dispersed social system. By means of radiotelemetry and bioacoustics we studied the olfactory and vocal behaviour during nocturnal dispersal and reunion of five sleeping groups.
All groups used 3–17 sleeping sites exclusively, suggesting a sleeping site-related territoriality and competition for them. The occurrence of olfactory and vocal behaviour showed an asymmetrical temporal distribution. Whereas marking behaviour was observed exclusively during dispersal, a particular call type, the trill, was used by all groups during reunions. Interestingly, these trills carried group-specific signatures.
Our findings provide the first empirical evidence for nocturnal primates in a natural environment that olfactory signals represent an important mechanism to regulate the distribution of different groups in space, whereas acoustic signals control intra-group cohesion and coordination.
A three month field study was conducted onCallicebus torquatus near the Nanay River in northern Peru. Data were collected primarily by the time sampling method. Information on daily movement,
vocalizations, population density, and social behavior is presented. The titi monkeys we studied have a family unit pattern
of social organization, territoriality accompanied by vocal activity, and a home range of about 20 hectares. There is a high
degree of parental investment in care of the infant on the part of the adult male.
An animal's vocalizations may be a useful reflection of its subjective state of welfare. We attempted to evaluate vocal response as an indication of animal distress. Calves (n=189) were randomly allotted to four treatment groups in a 2×2 factorial design, the factors being Branded vs. Not Branded and Restrained vs. Not Restrained. On four consecutive days calves were brought through a headgate and squeeze apparatus. Restrained calves were caught in the headgate for 3 to 5 s. The remainder were stopped at the headgate but not restrained. On day 5, all calves were captured and restrained. Half the animals were hot-iron branded and half were sham branded using an unheated iron. During branding, vocalizations were recorded. Digitized files were used to generate an audiospectrogram and a power spectrum for each call. We analysed 167 calls. During treatment, 65 calves vocalized. More branded than non-branded animals vocalized (58/95 compared with 7/94, P<0.0001). Branded animals showed a greater frequency range in the fundamental, or lowest harmonic, of the audiospectrogram, (68.04 Hz±5.33 compared with 28 Hz±8.74, P<0.05), a higher maximum frequency (186.66 Hz±5.19 compared with 141.6 Hz±6.6, P<0.01). and a higher peak sound level (P<0.05). The previous 4 days of restraint did not alter the probability of vocalizing, or any characteristics of the calls. This suggests that measuring vocal response may be particularly useful when the effects of relatively severe stressors are being investigated. The insensitivity of vocal response to moderate levels of stress may offer an advantage over cortisol or heart rate measurements which can reach high values in response to situational factors, leaving little capacity to respond to treatment. Analysis of vocalization may be among the more reliable and least invasive methods of assessing acute distress in cattle. Based on findings of this study, we suggest that vocalization data should be interpreted as statistical properties of a treatment group, rather than indicating the condition of any individual animal.
Findings are presented from a 9-week field study on Aotus trivirgatus in continuous primary, tropical forest in Peru. One group of 2 adults and 2 juveniles utilized the same lodge area in the center of a home range of 3.1 ha for the duration of the study. The group utilized eleven fruit trees of nine different species during the 9 weeks. The home range overlapped extensively with that of other Aotus groups.
During experiments concerning the communication of squirrel monkeys, it proved to be necessary to construct an automatic apparatus for the identification of individual calls (MAURUS et al. 1970). The aim of this paper was to furnish the necessary data to achieve this (frequency, duration and the relationship of the intensity between the fundamental frequency and the overtones). 6120 calls from 19 animals were analysed and were subdivided into 52 call types. It was thereby shown: 1. That the vocal repertoire consists not of the discrete call types assumed up to now, but of graded ones; 2. that the animals could not be differentiated as individuals on the basis of the particular parameter of their calls. The distribution into 52 call types is not necessarily biologically significant. A final statement about the distribution of call types can be made only after the signal value of each call type has been determined.
Asociación Primatológica Colombiana
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Raven Pro 1.4 User’s Manual. Ithaca, The Cornell Lab of Ornithology
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Plan de Manejo Ambiental de la Cuchilla de Peñas Blancas y del Subia. Bogotá D.C., Colombia, Centro de Documentación Ambiental
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Blancas y del Subia. Bogotá D.C., Colombia, Centro de Documentación Ambiental. CAR -Corporación Autónoma Regional de Cundinamarca.
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RStudio: Integrated Development for R
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The Costs and Benefits of Nocturnality for Aotus Trivigatus (the Night Monkey)
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City University of New York.