I would like to thank Vicky M. Oelze and Lars Fehren-Schmitz for advising and reviewing my research. Funding was generously provided by the Koret Scholars Program. I would also like to thank all of the research staff at Greater Mahale Ecosystem and Research who provided and collected the camera trap footage for this study. Finally, I would like to thank Payton Sime and all other members of the Chimpanzee Coding Team.
Arcadi, A. C. (1996). Phrase structure of wild chimpanzee pant hoots: Patterns of production and interpopulation variability. American Journal of Primatology, 39(3), 159–178. https://doi.org/10.1002/(SICI)1098-2345(1996)39:3<159::AID-AJP2>3.0.CO;2-Y
Campbell, G., Kuehl, H., N’Goran Kouamé, P., & Boesch, C. (2008). Alarming decline of West African chimpanzees in Côte d’Ivoire. Current Biology, 18(19), R903–R904. https://doi.org/10.1016/j.cub.2008.08.015
Clark, A. P., & Wrangham, R. W. (1993). Acoustic analysis of wild chimpanzee pant hoots: Do Kibale Forest chimpanzees have an acoustically distinct food arrival pant hoot? American Journal of Primatology, 31(2), 99–109. https://doi.org/10.1002/ajp.1350310203
Crockford, C. (2019). Why does the chimpanzee vocal repertoire remain poorly understood and what can be done about it? In C. Boesch, R. Wittig, C. Crockford, L. Vigilant, T. Deschner, & F. Leendertz (Eds.), The Chimpanzees of the Taï Forest (1st ed., pp. 394–409). Cambridge University Press. https://doi.org/10.1017/9781108674218.025
Crockford, C. (2017). Vocalizing in chimpanzees is influenced by social-cognitive processes. Science Advances. 3(11)e1701742. DOI: 10.1126/sciadv.1701742
Crockford, C., Gruber, T., & Zuberbühler, K. (2018). Chimpanzee quiet hoo variants differ according to context. Royal Society Open Science, 5(5), 172066. https://doi.org/10.1098/rsos.172066
Davila-Ross, M., Jesus, G., Osborne, J., & Bard, K. A. (2015). Chimpanzees (Pan troglodytes) Produce the Same Types of ‘Laugh Faces’ when They Emit Laughter and when They Are Silent. PLOS ONE, 10(6), e0127337. https://doi.org/10.1371/journal.pone.0127337
Fedurek, P., Tkaczynski, P. J., Hobaiter, C., Zuberbühler, K., Wittig, R. M., & Crockford, C. (2021). The function of chimpanzee greeting calls is modulated by their acoustic variation. Animal Behaviour, 174, 279–289. https://doi.org/10.1016/j.anbehav.2021.02.002
Fröhlich, M., Sievers, C., Townsend, S. W., Gruber, T., & Schaik, C. P. van. (2019). Multimodal communication and language origins: Integrating gestures and vocalizations. Biological Reviews, 94(5), 1809–1829. https://doi.org/10.1111/brv.12535
Gruber, T., & Zuberbühler, K. (2013). Vocal Recruitment for Joint Travel in Wild Chimpanzees. PLOS ONE, 8(9), e76073. https://doi.org/10.1371/journal.pone.0076073
Lehmann, J., Korstjens, A. H., & Dunbar, R. I. M. (2007). Fission–fusion social systems as a strategy for coping with ecological constraints: A primate case. Evolutionary Ecology, 21(5), 613–634. https://doi.org/10.1007/s10682-006-9141-9
Luncz, L. V., & Boesch, C. (2015). The extent of cultural variation between adjacent chimpanzee ( Pan troglodytes verus ) communities; A microecological approach: CULTURAL DIVERSITY IN CHIMPANZEE NEIGHBORS. American Journal of Physical Anthropology, 156(1), 67–75. https://doi.org/10.1002/ajpa.22628
Mitani, J. (2009). Male chimpanzees form enduring and equitable social bonds. Animal Behaviour, 77, 633–640. https://doi.org/10.1016/j.anbehav.2008.11.021
Mitani, J. C., Merriwether, D. A., & Zhang, C. (2000). Male affiliation, cooperation and kinship in wild chimpanzees. Animal Behaviour, 59(4), 885–893. https://doi.org/10.1006/anbe.1999.1389
Nishida, T. (1983). Alpha status and agonistic alliance in wild chimpanzees (Pan troglodytes schweinfurthii). Primates, 24(3), 318–336. https://doi.org/10.1007/BF02381978
Nishida, T. (1997). Sexual behavior of adult male chimpanzees of the Mahale Mountains national park, Tanzania. Primates, 38(4), 379–398. https://doi.org/10.1007/BF02381879
Nishida, T., Corp, N., Hamai, M., Hasegawa, T., Hiraiwa-Hasegawa, M., Hosaka, K., Hunt, K. D., Itoh, N., Kawanaka, K., Matsumoto-Oda, A., Mitani, J. C., Nakamura, M., Norikoshi, K., Sakamaki, T., Turner, L., Uehara, S., & Zamma, K. (2003). Demography, female life history, and reproductive profiles among the chimpanzees of Mahale. American Journal of Primatology, 59(3), 99–121. https://doi.org/10.1002/ajp.10068
Notman, H., & Rendall, D. (2005). Contextual variation in chimpanzee pant hoots and its implications for referential communication. Animal Behaviour, 70(1), 177–190. https://doi.org/10.1016/j.anbehav.2004.08.024
Samuni, L., Mielke, A., Preis, A., Crockford, C., & Wittig, R. M. (2020). Intergroup Competition Enhances Chimpanzee (Pan troglodytes verus) In-group Cohesion. International Journal of Primatology, 41(2), 342–362. https://doi.org/10.1007/s10764-019-00112-y
Schamberg, I., Wittig, R. M., & Crockford, C. (2018). Call type signals caller goal: A new take on ultimate and proximate influences in vocal production. Biological Reviews, 93(4), 2071–2082. https://doi.org/10.1111/brv.12437
Seyfarth, R. M., & Cheney, D. L. (2003). Signalers and Receivers in Animal Communication. Annual Review of Psychology, 54(1), 145–173. https://doi.org/10.1146/annurev.psych.54.101601.145121
Slocombe, K. E., & Zuberbühler, K. (2007). Chimpanzees modify recruitment screams as a function of audience composition. Proceedings of the National Academy of Sciences, 104(43), 17228–17233. https://doi.org/10.1073/pnas.0706741104
Sugiyama, Y., & Koman, J. (1979). Social structure and dynamics of wild chimpanzees at Bossou, Guinea. Primates, 20(3), 323–339. https://doi.org/10.1007/BF02373387
Taglialatela, J. P., Russell, J. L., Schaeffer, J. A., & Hopkins, W. D. (2009). Visualizing Vocal Perception in the Chimpanzee Brain. Cerebral Cortex, 19(5), 1151–1157. https://doi.org/10.1093/cercor/bhn157
Taglialatela, J. P., Russell, J. L., Schaeffer, J. A., & Hopkins, W. D. (2011). Chimpanzee Vocal Signaling Points to a Multimodal Origin of Human Language. PLOS ONE, 6(4), e18852. https://doi.org/10.1371/journal.pone.0018852
Van Lawick-Goodall, J. (1968). The Behaviour of Free-living Chimpanzees in the Gombe Stream Reserve. Animal Behaviour Monographs, 1, 161-IN12. https://doi.org/10.1016/S0066-1856(68)80003-2
Vink, D. N., Stewart, F. A., & Piel, A. K. (2020). Comparing Methods for Assessing Chimpanzee (Pan troglodytes schweinfurthii) Party Size: Observations, Camera Traps, and Bed Counts from a Savanna–Woodland Mosaic in the Issa Valley, Tanzania. International Journal of Primatology, 41(6), 901–915. https://doi.org/10.1007/s10764-020-00142-x
