Abstract
Duetting or chorusing behaviour occurs in a wide variety of animals and is posited to fulfil various important functions including territory defence and social bonding. The structure of calls produced in choruses might be shaped in a way that facilitates such joint vocal displays. In this study, we test the hypothesis that flexibility to modify the temporal structure of chimpanzee pant-hoots, vocalisations often given jointly with other individuals, facilitates chorusing. The results of this study, which was conducted on two communities of wild chimpanzees in Uganda, support this hypothesis. First, the duration of the build-up phase of the pant-hoot correlated with the latency with which the partner joined in the call, suggesting that males prolong the duration of the build-up to allow others to join in the call and to increase the likelihood of a chorus occurring. Second, the loud climax phases were significantly longer when produced in choruses than alone, which suggests that males prolong this part of the call when calling in choruses. Within chorus pant-hoots, there was a positive relationship between the number of climax elements given by two calling partners, suggesting that males adjust the temporal structure of their call to mirror their partner's call. We conclude that the basic acoustic structure of chimpanzee pant-hoots and the flexibility with which males adjust the duration of the constituent phases promote chorusing, and that the temporal structure of this rather stereotyped vocalisation is sensitive to fine details of the vocal responses of the audience.
| Original language | English |
|---|---|
| Pages (from-to) | 1781-1789 |
| Number of pages | 9 |
| Journal | Behavioral Ecology and Sociobiology |
| Volume | 67 |
| Issue number | 11 |
| DOIs | |
| Publication status | Published - Nov 2013 |
Funding
We would like to thank the directors of the Kibale Chimpanzee Project, Richard Wrangham and Martin Muller, for allowing us to conduct this research on the Kanyawara chimpanzees. Thank you to the KCP field manager, Emily Otali, and KCP field assistants, Francis Mugurusi, Solomon Musana, James Kyomuhendo, Wilberforce Tweheyo, Sunday John and Christopher Irumba, who were extremely helpful during the fieldwork. We thank Klaus Zuberbuhler for permission to work with the Budongo chimpanzees and the Royal Zoological Society of Scotland for providing core funding for the Budongo Conservation Field Station. We are grateful to Budongo field assistants, Monday Gideon, Jacob Alio, Sam Adue, Jackson Okuti and Robert Eguma, for invaluable assistance with data collection. We also thank Ed Donnellan for assisting with the analysis for this paper. We are grateful to Klaus Zuberbuhler, Richard Wrangham, Martin Muller, Geoffrey Hall and Stuart Semple for useful comments on a draft of this manuscript and to the editor David Watts, Robert Seyfarth, and an anonymous reviewer for helpful comments on the manuscript. PF was funded by a BBSRC studentship, a Leakey Foundation General Grant and an American Society of Primatologists General Small Grant. AS and KS were funded by a BBSRC project grant to KS.
Keywords
- Chimpanzees
- Pant-hoot chorusing
- Acoustic structure
- Vocal plasticity
- WILD CHIMPANZEES
- HYLOBATES SYNDACTYLUS
- DUET SONGS
- PAIR BONDS
- EVOLUTION
- COMMUNICATION
- VARIABILITY
- COOPERATION
- HYPOTHESES
- MECHANISMS