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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
    Accès libre
    Predator-deterring alarm call sequences in Guereza colobus monkeys are meaningful to conspecifics
    (2010)
    Schel, Anne Marijke
    ;
    Candiottia, Agnès
    ;
    Zuberbühler, Klaus 
    Guereza colobus monkeys, Colobus guereza, produce acoustically conspicuous vocalizations, the roars, in response to their main predators, leopards, Panthera pardus, and crowned eagles, Stephanoaetus coronatus. Roaring alarm utterances generally consist of the same basic call types but differ in overall structural composition. Leopards trigger roaring alarms containing many roaring sequences of only a few calls each, while eagles trigger few sequences with many calls each. To investigate whether conspecifics extract meaning from these structural differences, we played back leopard and eagle alarm call sequences and compared the monkeys’ responses in terms of their locomotor, gaze and vocal behaviour with their responses to the corresponding predator vocalizations. Locomotor responses did not differ between playback conditions; movement was always towards the simulated caller with no clear patterns in the vertical plane. Gaze direction, however, was highly predator specific. When hearing leopard-related stimuli, monkeys were significantly more likely to scan the area beneath them than when hearing eagle-related stimuli, which caused more scanning above. Vocal response rates to conspecific alarms were generally low but comparable with rates to the corresponding predators. If monkeys called, however, they produced the matching call sequences. Overall, our results showed that Guerezas discriminated between predator alarm call sequences produced by unfamiliar conspecifics and responded to them in predator-specific ways. Since the sequences were composed of the same basic call types, we concluded that the monkeys attended to the compositional aspects of these utterances.
  • Publication
    Accès libre
    Male blue monkeys alarm call in response to danger experienced by others
    Papworth, Sarah
    ;
    Böse, Anne-Sophie
    ;
    Barker, Jessica
    ;
    Schel, Anne Marijke
    ;
    Zuberbühler, Klaus 
    Male blue monkeys (Cercopithecus mitis stuhlmanni) of Budongo Forest, Uganda, produce two acoustically distinct alarm calls: hacks to crowned eagles (Stephanoaetus coronatus) and pyows to leopards (Panthera pardus) and a range of other disturbances. In playback experiments, males responded to leopard growls exclusively with a series of pyows and to eagle shrieks predominantly with hacks. Responses to playbacks of these alarm call series matched the responses to the corresponding predators, suggesting that the calls conveyed something about the nature of the threat. When responding to a series of hacks, indicating an eagle, males responded predominately with hacks, but produced significantly more calls if their group members were close to the playback stimulus than far away, regardless of their own position. When responding to a series of pyows, indicating a range of disturbances, males responded with pyows, but call rates were independent of the distance of other group members. The results suggest that males took into account the degree of danger experienced by other group members.
  • Publication
    Accès libre
    Responses to leopards are independent of experience in Guereza colobus monkeys
    Schel, Anne Marijke
    ;
    Zuberbühler, Klaus 
    How primates learn to recognise the predatory species from their animate world is a largely unresolved problem. We conducted predator encounter experiments with wild Guereza colobus monkeys of the Sonso area of Budongo Forest, Uganda. The monkeys are hunted by crowned eagles and chimpanzees, but not leopards, which have been locally extinct for decades. Despite their unfamiliarity with this predator, monkeys reliably produced appropriate anti-predator behaviour to leopards, which was indistinguishable from that of a neighbouring population, where leopards are present. In both populations, monkeys produced the same vocal responses and predator-specific alarm calls, although leopard-naïve monkeys were more inclined to approach when hearing a leopard than monkeys that were familiar with this predator. Control experiments showed that the monkeys’ response pattern was not due to the effects of unfamiliarity or conspicuousness of the experimental stimuli. Natural selection appears to have endowed these primates with a cognitive capacity to recognise direct signs of leopard presence as inherently dangerous requiring specific anti-predator responses.
  • Publication
    Accès libre
    Interspecies semantic communication in two forest primates
    Zuberbühler, Klaus 
    West African Diana monkeys (Cercopithecus diana) and Campbell's monkeys (Cercopithecus campbelli) frequently form mixed-species associations. Males of both species produce acoustically distinct alarm calls to crowned eagles (Stephanoaetus coronalus) and leopards (Panthera pardus), two of their main predators. Field playback experiments were conducted to investigate whether Diana monkeys respond to Campbell's alarm calls and whether they understand the calls' semantic content. Diana monkeys responded to playback of Campbell's leopard or eagle alarm calls as though the original predator were present. In a second experiment, Diana monkeys were primed with either Campbell's eagle or leopard alarm calls and then subsequently probed with the vocalizations of a crowned eagle or a leopard. Results showed that monkeys used the semantic information conveyed by the Campbell's alarm calls to predict the presence of a predator. The data are consistent with the hypothesis that non-human primates are able to use acoustic signals of diverse origin as labels for underlying mental representations.
  • Publication
    Accès libre
    Leopard predation and primate evolution
    Zuberbühler, Klaus 
    ;
    Jenny, David
    Although predation is an important driving force of natural selection its effects on primate evolution are still not well understood, mainly because little is known about the hunting behaviour of the primates' various predators. Here, we present data on the hunting behaviour of the leopard (Panthera pardus), a major primate predator in the Tai"forest of Ivory Coast and elsewhere. Radio-tracking data showed that forest leopards primarily hunt for monkeys on the ground during the day. Faecal analyses confirmed that primates accounted for a large proportion of the leopards' diet and revealed in detail the predation pressure exerted on the eight different monkey and one chimpanzee species. We related the species-specific predation rates to various morphological, behavioural and demographic traits that are usually considered adaptations to predation (body size, group size, group composition, reproductive behaviour, and use of forest strata). Leopard predation was most reliably associated with density, suggesting that leopards hunt primates according to abundance. Contrary to predictions, leopard predation rates were not negatively, but positively, related to body size, group size and the number of males per group, suggesting that predation by leopards did not drive the evolution of these traits in the predicted way. We discuss these findings in light of some recent experimental data and suggest that the principal effect of leopard predation has been on primates' cognitive evolution.
  • Publication
    Accès libre
    The alarm call system of female Campbell's monkeys
    Ouattara, Karim
    ;
    Zuberbühler, Klaus 
    ;
    N'Goran, Koffi J.-N
    ;
    Gombert, Jean-Emile
    Field studies on male forest guenon alarm-calling behaviour have revealed a number of intricacies about how these primates use vocalizations to protect themselves from predation. In these species, the vocal behaviour of adult females is often different from that of the males, but little systematic work has been done. Here, we describe the alarm call system of female Campbell's monkeys, Cercopithecus campbelli, in their natural forest habitat in western Ivory Coast. We found that in response to disturbing events, females produced three basic alarm call types, ‘wak-oos’, ‘hoks’ and acoustically variable ‘trill’ calls, consisting of repeated and rapidly ascending (RRA) pulses, which varied systematically in the temporal and frequency domains. Using observational and experimental data we were able to demonstrate that the RRA calls consisted of four acoustic variants, which could be associated with specific contexts, allowing listeners to draw inferences about the type of disturbance experienced by the caller. We also compared the alarm call behaviour of free-ranging individuals with published results from captivity. As predicted, captive individuals failed to produce predator-specific alarm calls, but they also produced an RRA variant in response to humans that was absent in the wild. We discuss the relevance of these findings in terms of their broader potential impact on evolutionary theories of primate communication.
  • Publication
    Accès libre
    The functional significance of Diana monkey 'clear' calls
    Uster, Dana
    ;
    Zuberbühler, Klaus 
    In their natural West African rainforest habitat, Diana monkeys continuously produce high rates of a close-range clear-sounding call, but the function of this behaviour is unknown. In other primate species, close-range calls are typically given in socially relevant situations, for example, to gain access to grooming partners or food. Quite contrarily, we tested a number of hypotheses and found that Diana monkey 'clear' calls primarily function to avoid predation. Call rates were significantly elevated when predation threat was high, for instance when the visibility was poor, when the group spread was large, when the group was not associated with other monkey species. or after alarm calls. Call rates were not significantly elevated, however, in circumstances of high social competition, for instance when the group spread was small, during resting phases, while feeding oil clumped food sources, or when foraging in the periphery where inter-group encounters were more likely to occur. Calling was contagious in that calls typically elicited vocal responses from out-of-sight group members within a few seconds. Because of this, callers can effectively monitor a much larger area than is visually accessible to single individuals, suggesting that Diana monkey clear calls act as an essential element in a mutualistic system of co-ordinated vigilance.
  • 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.