A pilot study of calling patterns and vocal turn-taking in wild bonobos Pan paniscus

Highlights

• This pilot study shows that wild bonobos display the fundamental temporal rules of vocal turn-taking

• Occurrences of calling patterns are in line with the unique observation collected from a captive group

• Calling patterns do not differ significantly with age and sex

• Calling patterns appear context-dependent

In several species of non-human primates, non-agonistic vocal exchanges can be seen as a primitive form of conversation, as they respect basic temporal rules (i.e. turn-taking, overlap avoidance), the same as those that guide human conversations. Conversational rules have recently been suggested in captive great ape species, yet the only study investigating vocal turn-taking in wild great apes did not find any evidence of such vocal roles. Whether the environmental conditions (captivity versus free ranging) or the social organisation of a given species shape temporally ruled vocal exchanges remain open questions. Here, we investigated general calling patterns of peaceful vocal exchanges in a wild bonobo community. This pilot study revealed that wild bonobos respect the fundamental temporal rules of vocal turn-taking, namely the avoidance of overlapping and the presence of short call-intervals between interlocutors on the order of 2 sec, corroborating findings from captive bonobos. Despite the limited sample size, our finding suggests that vocal exchanges appear context-dependent but neither age nor sex seem to influence their occurrence. While further studies are needed to confirm these observations, this study helps to fill a major gap in research on the vocal communication of wild great apes, paving the way for more extensive comparative studies, representing a further step towards a better understanding of how vocal turn-taking arose in humans.

KEY WORDS:

• wild bonobo
• vocal communication
• vocal behaviour
• calling patterns
• vocal turn-taking

Acknowledgements

We are very grateful to the NGO Mbou-Mon-Tour for logistical support and for providing access to the Manzano forest, to field assistants who accompanied us in forest, as well as the Embirima inhabitants and their Chief for a warm welcome. We thank two anonymous reviewers who provided helpful comments on the previous version of this manuscript. Lastly, we thank Katarzyna Pisanski for English corrections and scientific input.

DISCLOSURE STATEMENT

No potential conflict of interest was reported by the authors.

ETHICAL STANDARD

All methods were carried out in accordance with the relevant international guidelines and regulations, and were approved by the Institutional Animal Ethical Committee of the University of Lyon/Saint-Etienne, under the authorisation no. 42-218-0901-38 SV 09 (Lab ENES) and by the Congolese partner Mbou-Mon-Tour (MMT) that supervises the local research programs of the community-based conservation project. This study involved only behavioural observations and spontaneous vocal recordings of animals in their natural social group and environment. No experimental protocols nor invasive methods were used in this study.

AUTHOR CONTRIBUTION

C. Cornec and F. Levréro conceived, designed and coordinated the study. F. Levréro allocated research funding. C. Cornec and M. Ngofuna collected data. C. Cornec and F. Levréro carried out the statistical analyses and interpreted the data. C. Cornec, F. Levréro and A. Lemasson drafted the manuscript. V. Narat and C. Monghiemo supported the study implementation in the Manzano forest. All authors gave final approval for publication and agree to be held accountable for the work performed therein.

DATA ACCESSIBILITY

The raw data supporting this research are openly available on the Open Science Framework (DOI 10.17605/OSF.IO/T9N8A).

Additional information

Funding

This study was financially supported by the program IDEXLYON Agence Nationale de la Recherche ANR-16-IDEX-0005 (F. Levréro grant), the University of Lyon/Saint-Etienne, and the Labex CeLyA.