Since 2008, Professors Rebecca Chancellor and Aaron Rundus, faculty at West Chester University, and the Forest of Hope Association, have been coordinating a long-term field study of a population of approximately thirty eastern chimpanzees (Pan troglodytes schweinfurthii) living in Gishwati. Gishwati lies within the Congo-Nile Divide, one of six landscapes of the Albertine Rift. As such, it is an important link in a chain of chimpanzee sites within this region. The forest has a history of deforestation extending over the previous 50 years. We seek to understand how feeding competition, social interactions, and culture are influenced by the ecological constraints of living in a fragmented tropical montane rainforest.

One of our publications (Chancellor et al. 2012a) examines the influence of seasonal variation on chimpanzee fallback food consumption, nest group size, and habitat use. Chimpanzees are exceptionally vulnerable to forest fragmentation, but little is known about the effects of such fragmentation on chimpanzee feeding ecology. Our research has revealed that chimpanzees in Gishwati experience a substantial seasonal reduction in preferred fruit availability, which leads to a seasonal shift to more fibrous foods, including several that function as fallback foods. Our results also suggest that fallback foods are particularly important in small forest fragments, which experience significant periods of fruit scarcity but provide limited seasonal ranging alternatives. To understand how fruit scarcity and a large reliance on fallback foods affects chimpanzee sociality, we are currently collecting detailed behavioral observations of feeding, social, and cultural behavior such as tool use. Ultimately, our findings of chimpanzees will be applicable to human evolution. Similar ecological constraints due to fragmentation may have provoked similar responses in early hominins.

We are also involved in several research collaborations, including examining the genetic relatedness of the Gishwati chimpanzee population in collaboration with the Max Planck Institute (Chancellor et al. 2012b). Our results suggest that even though the Gishwati chimpanzee population is currently isolated from other chimpanzee populations, the genetic diversity observed is similar to that in other communities and is consistent with expectations for a population that has been isolated for a relatively short time. Ultimately, examining chimpanzee genetic variation in small forest populations may help us to understand more about past human population bottlenecks. We are currently collaborating with colleagues at Emory University to analyze fecal samples from the Gishwati chimpanzee population for the prevalence of parasites, which will further elucidate our understanding of the effects of forest fragmentation on population health and viability. We are also collaborating with the Max Planck Pan African Programme, in which we are collecting ecological, social, demographic, and behavioral data in an effort to help understand the diversification of behavior and tool use complexity in our closest living relatives.

In addition to our research on chimpanzees, we have recently begun investigating the behavioral ecology of golden monkeys (Cercopithecus mitis kandti) living in Gishwati. As a first step, we are collecting demographic, feeding, and ranging data to document their feeding ecology. Golden monkeys have a very limited distribution, occurring only in the Virunga Mountains and in Gishwati. Our project is the first to examine the Gishwati golden monkey population. We anticipate conducting a long-term comparative study of the Gishwati population and a population in Volcanoes National Park, Rwanda. Food resources, habitat quality, and the presence of chimpanzees as predators are all different between study sites, and we expect these differences will generate significant differences in feeding, ranging, and social behavior.

Principal Investigators:
Prof. Rebecca Chancellor, Department of Psychology, West Chester University and Dr. Aaron Rundus, Department of Psychology, West Chester University

Dr. Sylvain Nyandwi, Researcher, George Washington University

References

Chancellor, R. L., Rundus, A. S., & Nyandwi, S. (2012a). The influence of seasonal variation on chimpanzee (Pan troglodytes schweinfurthii) fallback food consumption, nest group size, and habitat use in Gishwati, a montane rainforest fragment in Rwanda. International Journal of Primatology, 33, 115-133.

Chancellor, R. L., Langergraber, K., Ramirez, S., Rundus, A. S., & Vigilant, L. (2012b). Genetic sampling of unhabituated chimpanzees (Pan troglodytes schweinfurthii) in Gishwati Forest Reserve, an isolated forest fragment in western Rwanda. International Journal of Primatology, 33, 479-488.

Other recent publication about Gishwati done in partnership with FHA.

Chancellor, R. L., Rundus, A. S., & Nyandwi, S. (2017). Chimpanzee seed dispersal in a montane forest fragment in Rwanda. American Journal of Primatology, Wiley Periodicals, Inc. DOI 10.1002/ajp.22624

Chancellor, R. L., Rundus, A. S., & Nyandwi, S. Nyiratuza M. Thierry A. (2020). Community‐based conservation and chimpanzee research in Gishwati forest, Rwanda. American Journal of Primatology, Wiley Periodicals, Inc. DOI: 10.1002/ajp.23195