| Autor: |
Rebout N; Physiologie de la Reproduction et des Comportements, CNRS, INRAE, Université de Tours, Nouzilly, France.; Fondazione Ethoikos, Radicondoli, Italy., De Marco A; Fondazione Ethoikos, Radicondoli, Italy.; Parco Faunistico di Piano dell'Abatino, Poggio San Lorenzo, Italy., Lone JC; Physiologie de la Reproduction et des Comportements, CNRS, INRAE, Université de Tours, Nouzilly, France., Sanna A; Fondazione Ethoikos, Radicondoli, Italy., Cozzolino R; Fondazione Ethoikos, Radicondoli, Italy., Micheletta J; Centre for Comparative and Evolutionary Psychology, Department of Psychology, University of Portsmouth, Portsmouth, UK.; Macaca Nigra Project, Tangkoko Reserve, Batu Putih, Indonesia., Sterck EHM; Department of Biology, Animal Ecology, Utrecht University, Utrecht, The Netherlands.; Animal Science Department, Biomedical Primate Research Center, Rijswijk, The Netherlands., Langermans JAM; Department Population Health Sciences, Veterinary Faculty, Utrecht University, Utrecht, The Netherlands.; Animal Science Department, Biomedical Primate Research Center, Rijswijk, The Netherlands., Lemasson A; EthoS (Ethologie Animale et Humaine), Université de Rennes, Université de Normandie, CNRS, Rennes, France., Thierry B; Physiologie de la Reproduction et des Comportements, CNRS, INRAE, Université de Tours, Nouzilly, France. |
| Abstrakt: |
We tested the social complexity hypothesis which posits that animals living in complex social environments should use complex communication systems. We focused on two components of vocal complexity: diversity (number of categories of calls) and flexibility (degree of gradation between categories of calls). We compared the acoustic structure of vocal signals in groups of macaques belonging to four species with varying levels of uncertainty (i.e. complexity) in social tolerance (the higher the degree of tolerance, the higher the degree of uncertainty): two intolerant species, Japanese and rhesus macaques, and two tolerant species, Tonkean and crested macaques. We recorded the vocalizations emitted by adult females in affiliative, agonistic and neutral contexts. We analysed several acoustic variables: call duration, entropy, time and frequency energy quantiles. The results showed that tolerant macaques displayed higher levels of vocal diversity and flexibility than intolerant macaques in situations with a greater number of options and consequences, i.e. in agonistic and affiliative contexts. We found no significant differences between tolerant and intolerant macaques in the neutral context where individuals are not directly involved in social interaction. This shows that species experiencing more uncertain social interactions displayed greater vocal diversity and flexibility, which supports the social complexity hypothesis. |
