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Bshary, Redouan

Nom
Bshary, Redouan
Affiliation principale
Fonction
Professeur ordinaire
Email
redouan.bshary@unine.ch
Identifiants
https://libra.unine.ch/handle/123456789/343
_
0000-0001-7198-8472

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  • Publication
    Accès libre
    Social-learning abilities of wild vervet monkeys in a two-step task artificial fruit experiment
    (2011)
    van de Waal, Erica
    ;
    Bshary, Redouan 
    Social learning is the basis for the formation of traditions in both human and nonhuman animals. Field observations and experiments provide evidence for the existence of traditions in animals but they do not address the underlying social-learning mechanisms. We used an established laboratory experimental paradigm, the artificial fruit design, to test for copying of a sequence of actions and local enhancement in six groups of wild vervet monkeys, Chlorocebus aethiops. We introduced a two-step task where models had to remove a bar to untie a rope that blocked a single door of a box. The models were high-ranking individuals that monopolized the box early on and discovered by trial and error how to open it. We obtained successful models in three groups, while the other three groups acted as controls. After 20 successful demonstrations, we tested subjects with a box that had a rope in the same position but the rope was not functional. Under these conditions, sequential copying of the two-step opening did not occur. Only individuals that were exposed to models were likely to touch the bar if door opening was not immediately successful, providing evidence for local enhancement. When we presented the boxes with the functional rope, we found no effect of having been exposed to a model on the probability that subjects solved the task. We conclude that the social-learning abilities of wild vervet monkeys are relatively limited and discuss potential problems concerning the technical difficulty of the task.
  • Publication
    Accès libre
    Selective attention to philopatric models causes directed social learning in wild vervet monkeys
    (2010)
    van de Waal, Erica
    ;
    Renevey, Nathalie
    ;
    Favre, Camille Monique
    ;
    Bshary, Redouan 
    Human behaviour is often based on social learning, a mechanism that has been documented also in a variety of other vertebrates. However, social learning as a means of problem-solving may be optimal only under specific conditions, and both theoretical work and laboratory experiments highlight the importance of a potential model's identity. Here we present the results from a social learning experiment on six wild vervet monkey groups, where models were either a dominant female or a dominant male. We presented ‘artificial fruit’ boxes that had doors on opposite, differently coloured ends for access to food. One option was blocked during the demonstration phase, creating consistent demonstrations of one possible solution. Following demonstrations we found a significantly higher participation rate and same-door manipulation in groups with female models compared to groups with male models. These differences appeared to be owing to selective attention of bystanders to female model behaviour rather than owing to female tolerance. Our results demonstrate the favoured role of dominant females as a source for ‘directed’ social learning in a species with female philopatry. Our findings imply that migration does not necessarily lead to an exchange of socially acquired information within populations, potentially causing highly localized traditions.
  • Publication
    Accès libre
    Differences in Diet Between Six Neighbouring Groups of Vervet Monkeys
    Tournier, Emilie
    ;
    Tournier, Virginia
    ;
    Van de Waal, Erica
    ;
    Barrett, Alan
    ;
    Brown, Leslie
    ;
    Bshary, Redouan 
    The comparative approach provides a powerful tool to study evolutionary questions on both intra- and interspecific variation. It has been applied to a great variety of taxa, including primates. Primate studies differ from those on most other taxa in two ways: first, data from most study sites contain information about only one group. Second, primatologists have used the comparative approach also to identify local traditions, that is, behaviours that spread through social learning. Here, we evaluate the appropriateness of such data by comparing the diet composition of six neighbouring groups of vervet monkeys, Cercopithecus aethiops. We used scan samples to collect diet data, and abundance measures and phenology to assess the availability of the 14 most important tree species utilised during the study. We calculated indices of diet overlap, which were highly variable and could be remarkably low. Furthermore, we found significant differences between group diets with respect to the relative utilisation of 13 of the 14 tree species. For all 13 species, we found positive correlations between local abundance and appearance in the diet, consistent with the importance of local ecology for diet composition. Nevertheless, more detailed comparisons of pairs of groups often revealed significant mismatches between the relative importance of a tree species and its local abundance. In conclusion, local variation merits increased attention by primatologists. While our results are compatible with the possibility that traditions exist on a local (group) rather than population scale, alternative explanations have to be considered.
  • Publication
    Accès libre
    Wild vervet monkey infants acquire the food-processing variants of their mothers
    Van de Waal, Erica
    ;
    Bshary, Redouan 
    ;
    Whiten, Andrew
    In the ability and motivation to copy others, social learning has been shown to provide a mechanism for the inheritance of behavioural traditions. Major questions remain about the circumstances and models that shape such social learning. Here, we demonstrate that behavioural food-processing variants among wild vervet monkey, Chlorocebus aethiops, mothers are matched by their infants in their first manipulative approaches to a new foraging problem. In our field experiment, grapes covered with sand were provisioned within groups of wild vervet monkeys that included experienced adults and 17 naïve infants. Monkeys dealt with the dirty food in four different ways. All infants first adopted their mother's way of handling the grapes, rather than those of other mothers or other monkeys eating nearby. Mothers who handled grapes in different ways had infants who were more likely to explore different approaches to handle the sandy grapes. Rarer cases of co-feeding siblings further suggest that copying may occur on the matriline level. Our findings suggest a capacity for detailed copying by infants of their mothers' and matriline members' food- processing techniques when encountering new foods, underlining the significance of familial models in such primate social groups.