V Dufour

Publications of V Dufour

• The impact of moving to a novel environment on social networks, activity and wellbeing in two new world primates.

  Authors: V Dufour, C Sueur, A Whiten, H M Buchanan-Smith

  American journal of primatology. 03/2011; 73(8):802-11.

  Among the stressors that can affect animal welfare in zoos, the immediate effect of relocation to a novel environment is one that has received little attention in the literature. Here, we compare theAmong the stressors that can affect animal welfare in zoos, the immediate effect of relocation to a novel environment is one that has received little attention in the literature. Here, we compare the social network, daily activity and the expression of stress-related behavior in capuchins (Cebus apella) and squirrel monkeys (Saimiri sciureus) before and just after they were relocated to a new enriched enclosure. Results showed similar immediate responses to the move in the two species. Both showed a substantial increase in the time spent resting and spent more time in the highest and "safest" part of their enclosure after relocation. Both capuchins and squirrel monkeys spent significantly more time in close proximity to other group members after relocation, compared to before. In squirrel monkeys, the structure of the social network, which was initially correlated to affiliation, was no longer so after the move. In capuchins, the network analysis showed that individuals regrouped by age, with the youngsters who were potentially more affected by stress being in the center of the network. Social network analysis helped to achieve a more complete picture of how individuals were affected by relocation. We suggest that this type of analysis should be used alongside traditional methods of observation and analysis to encompass the most complex aspects of animal behavior in times of stress and to improve welfare.

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• Calculated reciprocity after all: computation behind token transfers in orang-utans.

  Authors: V Dufour, M Pelé, M Neumann, B Thierry, J Call

  Biology letters. 01/2009;

  Transfers and services are frequent in the animal kingdom. However, there is no clear evidence in animals that such transactions are based on weighing costs and benefits when giving or returningTransfers and services are frequent in the animal kingdom. However, there is no clear evidence in animals that such transactions are based on weighing costs and benefits when giving or returning favours and keeping track of them over time (i.e. calculated reciprocity). We tested two orang-utans (Pongo pygmaeus abelii) in a token-exchange paradigm, in which each individual could exchange a token for food with the experimenter but only after first obtaining the token from the other orang-utan. Each orang-utan possessed tokens valuable to their partner but useless to themselves. Both orang-utans actively transferred numerous tokens (mostly partner-valuable) to their partner. One of the orang-utans routinely used gestures to request tokens while the other complied with such requests. Although initially the transfers were biased in one direction, they became more balanced towards the end of the study. Indeed, data on the last three series produced evidence of reciprocity both between and within trials. We observed an increase in the number and complexity of exchanges and alternations. This study is the first experimental demonstration of the occurrence of direct transfers of goods based on calculated reciprocity in non-human-primates.

• Chimpanzees fail to plan in an exchange task but succeed in a tool-using procedure.

  Authors: V Dufour, E.H.M. Sterck

  Behavioural processes. 10/2008; 79(1):19-27.

  Planning has long been considered a uniquely human capacity. Lately, however, it has been shown that apes and a corvid species act now to derive a material future benefit. Since primates are highlyPlanning has long been considered a uniquely human capacity. Lately, however, it has been shown that apes and a corvid species act now to derive a material future benefit. Since primates are highly social animals and their sociality is considered a strong selective force that resulted in complex cognitive capacities, planning is also expected in social situations. Unfortunately, prompting from social partners cannot be excluded in a social setting. Therefore, we controlled for this factor by testing the capacity to plan in chimpanzees using an exchange paradigm, that involves both a material and a social component, and a tool-use paradigm, similar to the one used on two other ape species. All chimpanzees failed to plan in the exchange task, but three individuals showed planning behavior in the tool-use task. Our methods controlled for the fact that chimpanzees were not prompted by the visibility of the reward at the moment of planning and also could not repeat a previously acquired routine. The best interpretation for our results is that chimpanzees can plan. However, planning was limited to the situation where the action to attain the future benefit only depended on a chimpanzee's own behavior.

• Chimpanzee (Pan troglodytes) anticipation of food return: coping with waiting time in an exchange task.

  Authors: V Dufour, M Pelé, E.H.M. Sterck, B Thierry

  Journal of comparative psychology (Washington, D.C. : 1983). 06/2007; 121(2):145-55.

  Despite controversial expectations that animals achieve reciprocal altruism, it is unclear if nonhuman species possess the necessary cognitive abilities. For reciprocal altruism, individuals mustDespite controversial expectations that animals achieve reciprocal altruism, it is unclear if nonhuman species possess the necessary cognitive abilities. For reciprocal altruism, individuals must anticipate the loss of a commodity and accept a delay before some return. The authors investigated the abilities of 5 chimpanzees (Pan troglodytes) to cope with increasing waiting duration in exchange tasks. Subjects had to keep a small cookie before returning it to a human partner to obtain a larger piece. For a piece 2, 4, or 8 times the size of the small piece, 3 of the 5 subjects waited for up to 4 min. For a piece 40 times larger, 4 of the 5 subjects waited up to 8 min. At long time lag, renouncement to wait occurred earlier than predicted by subjects' general waiting capacity, suggesting that the decision to wait was based on a trade-off between reward quantity and expected costs of the waiting duration. Chimpanzees could anticipate a delayed reward at a time scale of several minutes. If this reflects a cognitive limit in chimpanzees' anticipation capacity, reciprocal altruism by keeping track of costs and benefits over extended periods may be unlikely in chimpanzees.

• Accepting loss: the temporal limits of reciprocity in brown capuchin monkeys.

  Authors: A Ramseyer, M Pelé, V Dufour, C Chauvin, B Thierry

  Proceedings. Biological sciences / The Royal Society. 02/2006; 273(1583):179-84.

  Delayed reciprocity is a potentially important mechanism for cooperation to occur. It is however rarely reported among animals, possibly because it requires special skills like the ability to plan aDelayed reciprocity is a potentially important mechanism for cooperation to occur. It is however rarely reported among animals, possibly because it requires special skills like the ability to plan a loss. We tested six brown capuchin monkeys (Cebus apella) in such skills. Subjects were studied in exchange tasks in which they had to retain a food item for a given time lag before returning it to an experimenter and obtaining a more desirable reward. Experiments showed that the subjects could wait for several minutes when allowed to return only part of the initial item. When required to return the full item intact, however, most subjects could not sustain a time lag longer than 10 s. Although the duration of waiting increased with the amount of return expected by subjects, in most cases it did not extend beyond 20 s even when the eperimenter offered a food amount 40 fold the initial item. The failure of capuchin monkeys to sustain long-lasting waiting periods may be explained by limited self-control abilities. This would prevent them achieving reciprocal altruism.

• Chimpanzees fail to plan in an exchange task but succeed in a tool-using procedure

  Authors: V. Dufour, E.H.M. Sterck

  Behavioural Processes.

  Planning has long been considered a uniquely human capacity. Lately, however, it has been shown that apes and a corvid species act now to derive a material future benefit. Since primates are highlyPlanning has long been considered a uniquely human capacity. Lately, however, it has been shown that apes and a corvid species act now to derive a material future benefit. Since primates are highly social animals and their sociality is considered a strong selective force that resulted in complex cognitive capacities, planning is also expected in social situations. Unfortunately, prompting from social partners cannot be excluded in a social setting. Therefore, we controlled for this factor by testing the capacity to plan in chimpanzees using an exchange paradigm, that involves both a material and a social component, and a tool-use paradigm, similar to the one used on two other ape species. All chimpanzees failed to plan in the exchange task, but three individuals showed planning behavior in the tool-use task. Our methods controlled for the fact that chimpanzees were not prompted by the visibility of the reward at the moment of planning and also could not repeat a previously acquired routine. The best interpretation for our results is that chimpanzees can plan. However, planning was limited to the situation where the action to attain the future benefit only depended on a chimpanzee's own behavior.

• First test, then judge future-oriented behaviour in animals

  Authors: E.H.M. Sterck, V Dufour

• Chimpanzee anticipation of food return: Coping with waiting time in an exchang task

  Authors: V Dufour, M Pelé, E.H.M. Sterck, B Thierry