Testing the Frequency and Location of Chimpanzee Intergroup Interactions in Gombe National Park

Abstract

The study of intergroup interactions between chimpanzees (Pan troglodytes) is complex and integral in our understanding of certain human behaviors. For example, we can see how chimpanzees’ social behaviors impact reproductive success. We can also gain insights from their territorial behavior about humans and the evolution of warfare.

In 1960, Jane Goodall began the long-term study of chimpanzees in Gombe National Park, which has become the longest-running long-term field study of chimpanzees (Wilson 2012). Research by Goodall and her team has provided many significant insights into chimpanzees’ individual and social behavior. For most of the study’s duration, there were three chimpanzee communities in the park: the main study community, Kasekela, in the center, the Mitumba community in the north, and Kalande in the south (Wilson 2012). However, in the 2000s, the Kalande community declined precipitously (Rudicell et al., 2010) and by 2020 had only 5 members (Wilson et al., 2020). In contrast, the recent numbers show that the Mitumba and Kasekela communities have grown in numbers (Wilson et al. 2020).

The Gombe study provided some of the earliest detailed accounts of intergroup interactions in chimpanzees, including the first observations of intergroup killings (Goodall 1986). Because intergroup aggression is a leading cause of mortality for chimpanzees at Gombe (Williams et al., 2008), it is important to investigate factors that influence intergroup relations.

Data from these intergroup events have been extracted from the long-term record from approximately 1974 to 2007 (Massaro et al., 2021). In my research I updated this dataset by extracting intergroup events from recent monthly reports (2011-2023), to examine how the frequency and locations of intergroup interactions between the Kasekela and Mitumba communities has changed over time.