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Brandon C Wheeler - One of the best experts on this subject based on the ideXlab platform.
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RESEARCH ARTICLE Proximate Factors Underpinning Receiver Responses to Deceptive False Alarm Calls in Wild Tufted Capuchin Monkeys: Is It Counterdeception?
2013Co-Authors: Brandon C Wheeler, Kurt HammerschmidtAbstract:Previous research demonstrates that tufted capuchin monkeys use terrestrial Predator Alarm calls in a functionally deceptive manner to distract conspecifics when feeding on contestable resources, although the success of this tactic is limited because listeners frequently ignore these calls when given in such situations. While this decreased response rate is suggestive of a counterstrategy to deception by receivers, the proximate factors underpinning the behavior are unclear. The current study aims to test if the decreased response rate to Alarm calls in competitive contexts is better explained by the perception of subtle acoustic differences between Predator-elicited and deceptive false Alarms, or by receivers varying their responses based on the context in which the signal is received. This was tested by first examining the acoustic structure of Predator-elicited and deceptive false Alarms for any potentially perceptible acoustic differences, and second by comparing the responses of capuchins to playbacks of each of Predator-elicited and false Alarms, played back in noncompetitive contexts. The results indicate that deceptive false Alarms and Predator-elicited Alarms show, at best, minimal acoustic differences based on the structural features measured. Likewise, playbacks of deceptive false Alarms elicited antiPredator reactions at the same rate as did Predator-elicited Alarms, although there was a nonsignificant tendency for false Alarms to be more likely to elicit escape reactions. The lack of robust acoustic differences together with the high response rate to false Alarms in noncompetitive contexts suggests that the context in which the signal is received best explains receiver responses. It remains unclear, however, if listeners ascribe different meanings to the calls based on context, or if they generally ignore all signals in competitive contexts. Whether or not the decreased response rate of receivers directly stems from the deceptive use of the calls cannot be determined until these latter
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Proximate factors underpinning receiver responses to deceptive false Alarm calls in wild tufted capuchin monkeys: is it counterdeception?
American Journal of Primatology, 2012Co-Authors: Brandon C Wheeler, Kurt HammerschmidtAbstract:Previous research demonstrates that tufted capuchin monkeys use terrestrial Predator Alarm calls in a functionally deceptive manner to distract conspecifics when feeding on contestable resources, although the success of this tactic is limited because listeners frequently ignore these calls when given in such situations. While this decreased response rate is suggestive of a counterstrategy to deception by receivers, the proximate factors underpinning the behavior are unclear. The current study aims to test if the decreased response rate to Alarm calls in competitive contexts is better explained by the perception of subtle acoustic differences between Predator-elicited and deceptive false Alarms, or by receivers varying their responses based on the context in which the signal is received. This was tested by first examining the acoustic structure of Predator-elicited and deceptive false Alarms for any potentially perceptible acoustic differences, and second by comparing the responses of capuchins to playbacks of each of Predator-elicited and false Alarms, played back in noncompetitive contexts. The results indicate that deceptive false Alarms and Predator-elicited Alarms show, at best, minimal acoustic differences based on the structural features measured. Likewise, playbacks of deceptive false Alarms elicited antiPredator reactions at the same rate as did Predator-elicited Alarms, although there was a nonsignificant tendency for false Alarms to be more likely to elicit escape reactions. The lack of robust acoustic differences together with the high response rate to false Alarms in noncompetitive contexts suggests that the context in which the signal is received best explains receiver responses. It remains unclear, however, if listeners ascribe different meanings to the calls based on context, or if they generally ignore all signals in competitive contexts. Whether or not the decreased response rate of receivers directly stems from the deceptive use of the calls cannot be determined until these latter possibilities are rigorously tested. Am. J. Primatol. 75:715-725, 2013. © 2012 Wiley Periodicals, Inc.
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production and perception of situationally variable Alarm calls in wild tufted capuchin monkeys cebus apella nigritus
Behavioral Ecology and Sociobiology, 2010Co-Authors: Brandon C WheelerAbstract:Many mammalian and avian species produce conspicuous vocalizations upon encountering a Predator, but vary their calling based on risk urgency and/or Predator type. Calls falling into the latter category are termed “functionally referential” if they also elicit Predator-appropriate reactions in listeners. Functionally referential Alarm calling has been well documented in a number of Old World monkeys and lemurs, but evidence among Neotropical primates is limited. This study investigates the Alarm call system of tufted capuchin monkeys (Cebus apella nigritus) by examining responses to Predator and snake decoys encountered at various distances (reflecting differences in risk urgency). Observations in natural situations were conducted to determine if Predator-associated calls were given in additional contexts. Results indicate the use of three call types. “Barks” are elicited exclusively by aerial threats, but the call most commonly given to terrestrial threats (the “hiccup”) is given in nonPredatory contexts. The rate in which this latter call is produced reflects risk urgency. Playbacks of these two call types indicate that each elicits appropriate antiPredator behaviors. The third call type, the “peep,” seems to be specific to terrestrial threats, but it is unknown if the call elicits Predator-specific responses. “Barks” are thus functionally referential aerial Predator calls, while “hiccups” are better seen as generalized disturbance calls which reflect risk urgency. Further evidence is needed to draw conclusions regarding the “peep.” These results add to the evidence that functionally referential aerial Predator Alarm calls are ubiquitous in primates, but that noncatarrhine primates use generalized disturbance calls in response to terrestrial threats.
Michael J. Barry - One of the best experts on this subject based on the ideXlab platform.
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Effects of three phamaceuticals on the responses of tadpoles to Predator Alarm cues
Toxicological & Environmental Chemistry, 2018Co-Authors: Michael J. BarryAbstract:AbstractThe aim of this study is to measure the effects of two selective serotonin reuptake inhibitors, fluoxetine and sertraline, and one selective serotonin and norepinephrine reuptake inhibitor, venlafaxine, on the swimming and lateralization behaviour of Sclerophrys arabica tadpoles exposed to Predator Alarm cues. Tadpoles were exposed to the three pharmaceuticals either at 0.5 µg/L or 2.0 µg/L, either individually or as a mixture for 14 days. Control tadpoles and those exposed to high concentration of drugs individually or as a mixture, and those exposed to the low-concertation mixture reduced their swimming speed. Tadpoles exposed to 0.5 µg/L fluoxetine or venlafaxine did not respond to the Alarm cues. Tadpoles exposed to the mixture had similar responses to that of the control. Results indicate that these drugs have an additive mode of action. Tadpoles exposed to the low-concentration mixture increased lateralization of movement.
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Fluoxetine inhibits Predator avoidance behavior in tadpoles
Toxicological & Environmental Chemistry, 2014Co-Authors: Michael J. BarryAbstract:Fluoxetine is a selective serotonin re-uptake inhibitor used to treat anxiety and depression in humans. It has been detected as a contaminant in the surface waters in many countries. The effects of fluoxetine (0, 0.03, 0.3, and 3 μg L−1) on the swimming and behavioral responses of Bufo arabicus tadpoles to Alarm chemicals from Predatory dragonfly larvae (Anax imperator) were measured. Fluoxetine significantly reduced swimming speed at 0.3 and 3 μg L−1 in the absence of Predator Alarm chemicals but had no effect in their presence. Tadpoles exposed to Predator Alarm chemicals avoided open water and preferred to hide. Exposure to fluoxetine at 3 μg L−1 completely eliminated this Predator avoidance response, making the tadpoles more vulnerable to predation.
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Effects of fluoxetine on the swimming and behavioural responses of the Arabian killifish
Ecotoxicology, 2013Co-Authors: Michael J. BarryAbstract:The selective serotonin reuptake inhibitor fluoxetine has frequently been detected in surface waters around the world. Fluoxetine modulates levels of serotonin, a neurotransmitter that regulates several important physiological and behavioural processes including fear and anxiety, aggression, locomotion and feeding. In this study, groups of sub-adult Arabian killifish ( Aphanius dispar ) were exposed to either 0, 0.03, 0.3 or 3 μg/L fluoxetine hydrochloride for 7 days and their swimming behaviour and social interactions videotaped in a circular arena. The fish were subsequently exposed to a Predator Alarm chemical (from dragonfly larvae fed with A. dispar ) and their short-term responses recorded. The video was analysed using the open-sourced software program Ctrax which objectively quantified swimming and social behaviours. Aggression (chasing behaviour was significantly reduced at 3.0 μg/L fluoxetine. After the addition of the Predator Alarm chemicals fish responded quickly, increasing the percentage of time spent drifting or motionless and reducing average swimming velocity. Controls and fish exposed to 0.03 or 3 μg/L fluoxetine reduced swimming speed by 20–30 % but returned to pre-exposure velocities within 6 min. Fish exposed to 0.3 μg/L fluoxetine reduced swimming speed by 38 % after addition of the Predator Alarm and did not return to pre-exposure speeds during the recording period (19 min). Schooling behaviour was also affected by fluoxetine and Predator Alarm with fish exposed to 0.3 μg/L fluoxetine significantly reducing nearest neighbour distance and swimming speed relative to nearest neighbour the following addition of the Predator Alarm.
Kurt Hammerschmidt - One of the best experts on this subject based on the ideXlab platform.
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RESEARCH ARTICLE Proximate Factors Underpinning Receiver Responses to Deceptive False Alarm Calls in Wild Tufted Capuchin Monkeys: Is It Counterdeception?
2013Co-Authors: Brandon C Wheeler, Kurt HammerschmidtAbstract:Previous research demonstrates that tufted capuchin monkeys use terrestrial Predator Alarm calls in a functionally deceptive manner to distract conspecifics when feeding on contestable resources, although the success of this tactic is limited because listeners frequently ignore these calls when given in such situations. While this decreased response rate is suggestive of a counterstrategy to deception by receivers, the proximate factors underpinning the behavior are unclear. The current study aims to test if the decreased response rate to Alarm calls in competitive contexts is better explained by the perception of subtle acoustic differences between Predator-elicited and deceptive false Alarms, or by receivers varying their responses based on the context in which the signal is received. This was tested by first examining the acoustic structure of Predator-elicited and deceptive false Alarms for any potentially perceptible acoustic differences, and second by comparing the responses of capuchins to playbacks of each of Predator-elicited and false Alarms, played back in noncompetitive contexts. The results indicate that deceptive false Alarms and Predator-elicited Alarms show, at best, minimal acoustic differences based on the structural features measured. Likewise, playbacks of deceptive false Alarms elicited antiPredator reactions at the same rate as did Predator-elicited Alarms, although there was a nonsignificant tendency for false Alarms to be more likely to elicit escape reactions. The lack of robust acoustic differences together with the high response rate to false Alarms in noncompetitive contexts suggests that the context in which the signal is received best explains receiver responses. It remains unclear, however, if listeners ascribe different meanings to the calls based on context, or if they generally ignore all signals in competitive contexts. Whether or not the decreased response rate of receivers directly stems from the deceptive use of the calls cannot be determined until these latter
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Proximate factors underpinning receiver responses to deceptive false Alarm calls in wild tufted capuchin monkeys: is it counterdeception?
American Journal of Primatology, 2012Co-Authors: Brandon C Wheeler, Kurt HammerschmidtAbstract:Previous research demonstrates that tufted capuchin monkeys use terrestrial Predator Alarm calls in a functionally deceptive manner to distract conspecifics when feeding on contestable resources, although the success of this tactic is limited because listeners frequently ignore these calls when given in such situations. While this decreased response rate is suggestive of a counterstrategy to deception by receivers, the proximate factors underpinning the behavior are unclear. The current study aims to test if the decreased response rate to Alarm calls in competitive contexts is better explained by the perception of subtle acoustic differences between Predator-elicited and deceptive false Alarms, or by receivers varying their responses based on the context in which the signal is received. This was tested by first examining the acoustic structure of Predator-elicited and deceptive false Alarms for any potentially perceptible acoustic differences, and second by comparing the responses of capuchins to playbacks of each of Predator-elicited and false Alarms, played back in noncompetitive contexts. The results indicate that deceptive false Alarms and Predator-elicited Alarms show, at best, minimal acoustic differences based on the structural features measured. Likewise, playbacks of deceptive false Alarms elicited antiPredator reactions at the same rate as did Predator-elicited Alarms, although there was a nonsignificant tendency for false Alarms to be more likely to elicit escape reactions. The lack of robust acoustic differences together with the high response rate to false Alarms in noncompetitive contexts suggests that the context in which the signal is received best explains receiver responses. It remains unclear, however, if listeners ascribe different meanings to the calls based on context, or if they generally ignore all signals in competitive contexts. Whether or not the decreased response rate of receivers directly stems from the deceptive use of the calls cannot be determined until these latter possibilities are rigorously tested. Am. J. Primatol. 75:715-725, 2013. © 2012 Wiley Periodicals, Inc.
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Responses of Redfronted Lemurs to Experimentally Modified Alarm Calls: Evidence for Urgency-Based Changes in Call Structure
Ethology, 2002Co-Authors: Claudia Fichtel, Kurt HammerschmidtAbstract: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.
Klaus Zuberbühler - One of the best experts on this subject based on the ideXlab platform.
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An intentional vocalization draws others’ attention: A playback experiment with wild chimpanzees
Animal Cognition, 2015Co-Authors: Catherine Crockford, Roman M. Wittig, Klaus ZuberbühlerAbstract:A vital step in the evolution of language is likely to have been when signalers explicitly intended to direct recipients’ attention to external objects with the use of referential signals. Although animal signals can direct the attention of others to external events, such as in monkey Predator Alarm calls, there is little evidence that this is the result of an intention to inform the recipient. Two recent studies, however, indicate that the production of chimpanzee quiet Alarm calls, given to snakes, complies with some standard behavioral markers of intentional signaling, such as gaze alternation. But it is currently unknown whether the calls alone direct receivers’ attention to the threat. To address this, we carried out a playback experiment with free-ranging chimpanzees in Budongo Forest, Uganda, using a within-subjects design. From a hidden speaker, we broadcast either quiet Alarm ‘hoos’ (‘alert hoos’) or acoustically distinguishable hoos produced while resting (‘rest hoos’) and found a significant increase in search behavior after ‘alert’ compared with ‘rest’ hoos, with subjects monitoring either the call provider or the area near the call provider. In sum, chimpanzee ‘alert hoos’ represent a plausible case of an intentionally produced animal vocalization (other studies) that refers recipients to signalers and/or to an external event (this study).
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Predator-deterring Alarm call sequences in Guereza colobus monkeys are meaningful to conspecifics
Animal Behaviour, 2010Co-Authors: Anne Marijke Schel, Agnès Candiotti, Klaus ZuberbühlerAbstract: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.
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Predator-specific Alarm calls in Campbell's monkeys, Cercopithecus campbelli
Behavioral Ecology and Sociobiology, 2001Co-Authors: Klaus ZuberbühlerAbstract:One of the most prominent behavioural features of many forest primates are the loud calls given by the adult males. Early observational studies repeatedly postulated that these calls function in intragroup spacing or intergroup avoidance. More recent field experiments with Diana monkeys (Cercopithecus diana) of Tai Forest, Ivory Coast, have clearly shown that loud male calls function as Predator Alarm calls because calls reliably (1) label different Predator classes and (2) convey semantic information about the Predator type present. Here, I test the Alarm call hypothesis another primate, the Campbell's monkey (C. campbelli). Like Diana monkeys, male Campbell's monkeys produce conspicuous loud calls to crowned hawk eagles (Stephanoaetus coronatus) and leopards (Panthera pardus), two of their main Predators. Playback experiments showed that monkeys responded to the Predator category represented by the different playback stimuli, regardless of whether they consisted of (1) vocalisations of the actual Predators (crowned hawk eagle shrieks or leopard growls), (2) Alarm calls to crowned hawk eagles or leopards given by other male Campbell's monkeys or (3) Alarm calls to crowned hawk eagles or leopards given by sympatric male Diana monkeys. These experiments provide further evidence that non-human primates have evolved the cognitive capacity to produce and respond to referential labels for external events.
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Diana monkey long-distance calls : messages for conspecifics and Predators
Animal Behaviour, 1997Co-Authors: Klaus Zuberbühler, Ronald Noë, Robert M. SeyfarthAbstract:Abstract Primate long-distance calls have typically been interpreted as communication signals between conspecific groups (the ‘resource defence hypothesis’), but their potential role as anti-Predator Alarm calls has received comparably little attention. Male diana monkeys,Cercopithecus diana dianain the Tai forest of Cote d’Ivoire often utter long-distance calls, either spontaneously or in reaction to a variety of stimuli, including Predators and non-Predators. The present study focuses only on predation contexts and provides evidence for communication to both Predators and conspecifics. Males called only in response to Predators whose hunting success depends on unprepared prey, that is, leopards and crowned hawk eagles, but not in response to pursuit hunters, such as chimpanzees and humans, which can pursue the caller in the canopy. Calling was regularly combined with approaching the Predator. Both observations suggest that male long-distance calls are used to signal detection to the Predator (‘perception advertisement hypothesis’). Analysis of male long-distance calls given to leopards and eagles showed that they differed according to a number of acoustic parameters. The two call variants were played to different diana monkey groups; conspecifics responded to them as though the original Predator were present. We conclude that, in addition to their function in perception advertisement, diana monkey long-distance calls function as within-group semantic signals that denote different types of Predators.
Catherine Crockford - One of the best experts on this subject based on the ideXlab platform.
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An intentional vocalization draws others’ attention: A playback experiment with wild chimpanzees
Animal Cognition, 2015Co-Authors: Catherine Crockford, Roman M. Wittig, Klaus ZuberbühlerAbstract:A vital step in the evolution of language is likely to have been when signalers explicitly intended to direct recipients’ attention to external objects with the use of referential signals. Although animal signals can direct the attention of others to external events, such as in monkey Predator Alarm calls, there is little evidence that this is the result of an intention to inform the recipient. Two recent studies, however, indicate that the production of chimpanzee quiet Alarm calls, given to snakes, complies with some standard behavioral markers of intentional signaling, such as gaze alternation. But it is currently unknown whether the calls alone direct receivers’ attention to the threat. To address this, we carried out a playback experiment with free-ranging chimpanzees in Budongo Forest, Uganda, using a within-subjects design. From a hidden speaker, we broadcast either quiet Alarm ‘hoos’ (‘alert hoos’) or acoustically distinguishable hoos produced while resting (‘rest hoos’) and found a significant increase in search behavior after ‘alert’ compared with ‘rest’ hoos, with subjects monitoring either the call provider or the area near the call provider. In sum, chimpanzee ‘alert hoos’ represent a plausible case of an intentionally produced animal vocalization (other studies) that refers recipients to signalers and/or to an external event (this study).
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Context-specific calls in wild chimpanzees, Pan troglodytes verus: analysis of barks
Animal Behaviour, 2003Co-Authors: Catherine Crockford, Christophe BoeschAbstract:Abstract Context-specific calls, which have a distinct acoustic structure and are selectively produced in specific contexts, are a prerequisite for calls that function referentially. Functionally referential calls, which convey information to conspecifics about objects and events in the external world, have been found in a number of species, notably primates. Evidence of context-specific calls in apes, however, is largely absent. We analysed whether the barks of wild male chimpanzees in the Tai Forest, Cote d'Ivoire, are context specific. We examined the acoustic structure of barks, and other calls produced in association with barks, in six contexts, using discriminant function analysis. Chimpanzees produced context-specific signals in two ways. First, they produced two acoustically graded bark subtypes, in hunt and snake contexts, respectively. Second, they produced context-specific signal combinations of barks with acoustically different call types or drums. These signal combinations increased specificity levels in three of the six contexts to over 90%, a level similar to the classic vervet monkey, Cercophithecus aethiops , Predator Alarm calls. Furthermore, specific chimpanzee signals were produced in contexts other than Alarm, such as travel and hunting, where the potential benefits of evolving specific calls are less obvious. These signals may convey specific context information to listeners, and thus function referentially; however, to confirm this, analyses of listeners' responses are required. The results show that two strategies for producing context-specific signals seem to have evolved in a species other than humans: chimpanzees produce context-specific bark subtypes and context-specific signal combinations. Copyright 2003 Published by Elsevier Science Ltd on behalf of The Association for the Study of Animal Behaviour.