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Zuberbühler, Klaus

Nom
Zuberbühler, Klaus
Affiliation principale
Fonction
Professeur ordinaire
Email
klaus.zuberbuehler@unine.ch
Identifiants
https://libra.unine.ch/handle/123456789/670
_
0000-0001-8378-088X

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  • Publication
    Métadonnées seulement
  • Publication
    Métadonnées seulement
  • Publication
    Métadonnées seulement
    Suffixation influences receivers' behaviour in non-human primates
    (2015)
    Coye, Camille
    ;
    Ouattara, Karim
    ;
    Zuberbühler, Klaus 
    ;
    Lemasson, Alban
    Compared to humans, non-human primates have very little control over their vocal production. Nonetheless, some primates produce various call combinations, which may partially offset their lack of acoustic flexibility. A relevant example is male Campbell's monkeys (Cercopithecus campbelli), which give one call type ('Krak') to leopards, while the suffixed version of the same call stem ('Krak-oo') is given to unspecific danger. To test whether recipients attend to this suffixation pattern, we carried out a playback experiment inwhichwe broadcast naturally and artificially modified suffixed and unsuffixed 'Krak' calls of male Campbell's monkeys to 42 wild groups of Diana monkeys (Cercopithecus diana diana). The two species form mixed-species groups and respond to each other's vocalizations. We analysed the vocal response of male and female Diana monkeys and overall found significantly stronger vocal responses to unsuffixed (leopard) than suffixed (unspecific danger) calls. Although the acoustic structure of the 'Krak' stem of the calls has some additional effects, subject responses were mainly determined by the presence or the absence of the suffix. This study indicates that suffixation is an evolved function in primate communication in contexts where adaptive responses are particularly important.
  • Publication
    Métadonnées seulement
    Monkey semantics: two 'dialects' of Campbell's monkey alarm calls
    (2014)
    Schlenker, Philippe
    ;
    Chemla, Emmanuel
    ;
    Arnold, Kate
    ;
    Lemasson, Alban
    ;
    Ouattara, Karim
    ;
    Keenan, Sumir
    ;
    Stephan, Claudia 
    ;
    Ryder, Robin
    ;
    Zuberbühler, Klaus 
    We develop a formal semantic analysis of the alarm calls used by Campbell's monkeys in the Tai forest (Ivory Coast) and on Tiwai island (Sierra Leone)-two sites that differ in the main predators that the monkeys are exposed to (eagles on Tiwai vs. eagles and leopards in Tai). Building on data discussed in Ouattara et al. (PLoS ONE 4(11):e7808, 2009a; PNAS 106(51): 22026-22031, 2009b and Arnold et al. (Population differences in wild Campbell's monkeys alarm call use, 2013), we argue that on both sites alarm calls include the roots krak and hok, which can optionally be affixed with -oo, a kind of attenuating suffix; in addition, sentences can start with boom boom, which indicates that the context is not one of predation. In line with Arnold et al., we show that the meaning of the roots is not quite the same in Tai and on Tiwai: krak often functions as a leopard alarm call in Tai, but as a general alarm call on Tiwai. We develop models based on a compositional semantics in which concatenation is interpreted as conjunction, roots have lexical meanings, -oo is an attenuating suffix, and an all-purpose alarm parameter is raised with each individual call. The first model accounts for the difference between Tai and Tiwai by way of different lexical entries for krak. The second model gives the same underspecified entry to krak in both locations (= general alarm call), but it makes use of a competition mechanism akin to scalar implicatures. In Tai, strengthening yields a meaning equivalent to non-aerial dangerous predator and turns out to single out leopards. On Tiwai, strengthening yields a nearly contradictory meaning due to the absence of ground predators, and only the unstrengthened meaning is used.
  • Publication
    Métadonnées seulement
    Graded or discrete? A quantitative analysis of Campbell's monkey alarm calls
    (2013)
    Keenan, Sumir
    ;
    Lemasson, Alban
    ;
    Zuberbühler, Klaus 
    A 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. Crown Copyright (C) 2012 Published on behalf of The Association for the Study of Animal Behaviour by Elsevier Ltd. All rights reserved.
  • Publication
    Métadonnées seulement
    Voice discrimination in four primates
    (2013)
    Candiotti, Agnes
    ;
    Zuberbühler, Klaus 
    ;
    Lemasson, Alban
    One accepted function of vocalisations is to convey information about the signaller, such as its age-sex class, motivation, or relationship with the recipient. Yet, in natural habitats individuals not only interact with conspecifics but also with members of other species. This is well documented for African forest monkeys, which form semi-permanent mixed-species groups that can persist for decades. Although members of such groups interact with each other on a daily basis, both physically and vocally, it is currently unknown whether they can discriminate familiar and unfamiliar voices of heterospecific group members. We addressed this question with playbacks on monkey species known to form polyspecific associations in the wild: red-capped mangabeys, Campbell's monkeys and Guereza colobus monkeys. We tested subjects' discrimination abilities of contact calls of familiar and unfamiliar female De Brazza monkeys. When pooling all species, subjects looked more often towards the speaker when hearing contact calls of unfamiliar than familiar callers. When testing De Brazza monkeys with their own calls, we found the same effect with the longest gaze durations after hearing unfamiliar voices. This suggests that primates can discriminate, not only between familiar and unfamiliar voices of conspecifics, but also between familiar and unfamiliar voices of heterospecifics living within a close proximity. (C) 2013 Elsevier B.V. All rights reserved.
  • Publication
    Métadonnées seulement
    Language is not uniquely human, monkeys saying !
    (2011)
    Lemasson, Alban
    ;
    Hausberger, Martine
    ;
    Zuberbühler, Klaus 
  • Publication
    Accès libre
    Socially meaningful vocal plasticity in adult Campbell's monkeys (Cercopithecus campbelli)
    Lemasson, Alban
    ;
    Hausberger, Martine
    ;
    Zuberbühler, Klaus 
    Campbell's monkeys (Cercopithecus campbelli) frequently exchange vocalizations, the combined-harmonic calls, with individuals responding to one another's calls. Previous work has shown that these calls can be grouped into several structural variants. Adult females differ in their variant repertoires, which may change during their adult life, particularly after changes in the group composition. Playback of females' currently produced variants triggered vocal responses from other group members, whereas the same females' former, no longer used variants and those of stranger females never did. In contrast, former variants caused long-term cessation of vocal behavior, whereas stranger variants had no effect. Data showed that monkeys were able to distinguish between the different types of variants, indicating that these calls form part of a long-term social memory.
  • Publication
    Accès libre
    Campbell's monkeys concatenate vocalizations into context-specific call sequences
    Ouattara, Karim
    ;
    Lemasson, Alban
    ;
    Zuberbühler, Klaus 
    Primate vocal behavior is often considered irrelevant in modeling human language evolution, mainly because of the caller's limited vocal control and apparent lack of intentional signaling. Here, we present the results of a long-term study on Campbell's monkeys, which has revealed an unrivaled degree of vocal complexity. Adult males produced six different loud call types, which they combined into various sequences in highly context-specific ways. We found stereotyped sequences that were strongly associated with cohesion and travel, falling trees, neighboring groups, nonpredatory animals, unspecific predatory threat, and specific predator classes. Within the responses to predators, we found that crowned eagles triggered four and leopards three different sequences, depending on how the caller learned about their presence. Callers followed a number of principles when concatenating sequences, such as nonrandom transition probabilities of call types, addition of specific calls into an existing sequence to form a different one, or recombination of two sequences to form a third one. We conclude that these primates have overcome some of the constraints of limited vocal control by combinatorial organization. As the different sequences were so tightly linked to specific external events, the Campbell's monkey call system may be the most complex example of ‘proto-syntax’ in animal communication known to date.
  • Publication
    Accès libre
    Speed of call delivery is related to context and caller identity in Campbell’s monkey males
    Lemasson, Alban
    ;
    Ouattara, Karim
    ;
    Bouchet, Hélène
    ;
    Zuberbühler, Klaus 
    Call rate can be a salient feature in animal communication. Depending on the species, different psychological variables appear to influence call rates but the exact nature of these relationships remains poorly explored. Here, we demonstrate for free-ranging Campbell's monkeys that the call rates of four different alarm series (termed H, K, K+, and B series) vary systematically as a function of context, associated behaviour, and identity of the caller. K+ series were given more rapidly to predation than non- predation events, K+ and K series more rapidly to visual than auditory predator detection, and H series more rapidly while counterattacking an eagle than staying put. Finally, there were individual differences in B series, suggesting that call rate potentially provides listeners with cues about the caller's anti-predator behaviour, event type experienced, and his identity.