Date of Award
Doctor of Philosophy (PhD)
Socioecology involves understanding sociality and society though individual responses to the influences of environmental change. Further, specific socioecological factors (e.g., group size and composition, fruit availability and rainfall) have been shown to consistently impact health profiles in some primate populations. Aspects of the social structure of Western lowland gorillas (Gorilla gorilla gorilla) and their social interactions may make these apes more susceptible to having compromised immune profiles. In this dissertation, I took a multidisciplinary approach to explore the relationship between gorilla socioecology and health. Within the remote forests of the Congo Basin where emerging infectious diseases are a persistent threat, I had a unique opportunity to apply both cross-sectional and longitudinal approaches to quantifying behavioral and health profiles of wild gorillas across multiple social groups, group compositions, seasonal food distribution, and anthropogenic pressures. This was accomplished by studying five habituated gorilla groups which reside in the Goualougo and Djeke Triangles in the northern Republic of Congo over a period of several years, spanning 2014 to 2021. First, I assessed whether group composition and fruit availability influenced the rate of intergroup encounters in western lowland gorillas. The results indicated the number of subordinate males in the group correlated negatively with the occurrence of intergroup encounters, and groups were more likely to avoid interaction or react aggressively when they encountered a solitary male than when they encountered another group. Second, we evaluated potential socioecological predictors of respiratory illness and found that males were more likely to exhibit signs of respiratory illness than females, and increasing age resulted in a higher likelihood of symptomatic coughs or sneezes. Lastly, we explored how demographic factors shape transmission networks via social interactions and silverback nearest neighbor networks. We found that males were more social than females and that younger individuals were more social than older gorillas. Additionally, we observed more social behavior during months of higher fruit abundance. Both intergroup and intragroup connections were found to be very dense in these gorilla social networks, with only the removal of immatures and blackbacks affecting network transmissibility. Overall, we found a much higher level of behavioral plasticity among western lowland gorillas than expected which may facilitate mating opportunities, but may also create pathways for the flow of pathogens within and between groups. The results from the dissertation highlight the need for long-term monitoring of study groups and important role of systematic behavioral observations in assessing health and well-being at the individual and group levels. With disease being one of the persistent threats to declining primate populations, the multi-faceted methodologies and protocols used in this research may serve as a model for promoting cross site surveillance of the disease dynamics with primate communites and across landscapes which may be subjected to varying degrees of anthropogenic disturbance. This research also holds direct implications and applications for wildlife conservation more broadly, in that identification of the specific predictors and pathways of pathogen exchange can inform discussions about potential transmission mitigation strategies. The suite of methodological and analytical approaches could also be used to bolster existing best practice guidelines to safeguard other endangered species at risk of emerging infectious diseases.
Chair and Committee
Cooksey, Kristena E., "Socioecological Factors Influencing Health Profiles of Western Lowland Gorillas (Gorilla gorilla gorilla) in the Northern Republic of Congo" (2022). Arts & Sciences Electronic Theses and Dissertations. 2670.
Available for download on Thursday, May 20, 2027