Interconnected wildlife health and behavior play vital roles in population dynamics, ecosystem functions, biodiversity, and wildlife conservation. Research and public interest in zoonotic pathogen transmission — transmission from animals to humans — has increased with the COVID-19 pandemic and ongoing concern about zoonotic spillover from wildlife to people. Diverse zoonotic pathogens have been linked to wildlife reservoirs, highlighting the importance of understanding human-wildlife interfaces and interactions. However, humans and domestic animals impact the health and conservation of threatened and endangered species, including primates. Both primate and human behavior can influence the risk of pathogen transmission at the primate-human interface. While zoonotic pathogen sharing is of concern, less research has focused on pathogen transmission among wildlife and integrating social behavior into wildlife health research.
To better understand the links between primate social behavior and pathogen transmission, we used long-term ecological transect data from the Udzungwa Ecological Monitoring Centre and a cross-sectional survey of pathogen shedding in overlapping primate populations living in forests of varying protections status and human disturbance in the Udzungwa mountains of Tanzania. Our research quantifies inter-specific associations among free-ranging primates in two forest blocks of the Udzungwa Mountains to investigate the relationship between forest protection status and inter-specific associations. Using bias-reduced logistic regression and social network analysis, we found significant and varied trends in inter-specific associations in well and less protected forests among primate species. We then examined the relationship between habitat primate inter-specific associations in the well-protected Mwanihana forest. Using mixed model logistic regression and a co-occurrence checkerboard score, we found that habitat and species were significant predictors of inter-specific associations. We found strong inter-specific associations between Udzungwa red colobus (Piliocolobus gordonorum) and Peter’s Angola colobus (Colobus angolensis palliatus) across habitats. To investigate connections between primate social interactions and health, we assessed the relationship between viral shedding and interspecific interactions observed in the field. While the relationship was not significant, the majority of animals with viral shedding detected were sampled at sites with inter-specific associations. These results highlight the need for integrated wildlife behavior and health research to understand connections between primate social interactions and pathogen transmission.