This dissertation addresses the escalating threat of anthropozoonosis at human-wildlife interfaces by investigating the social dynamics of disease transmission among wildlife populations, focusing particularly on long-tailed macaques (Macaca fascicularis) inhabiting human-wildlife interface areas. Tuberculosis (TB) serves as the model infectious disease due to its high prevalence in Southeast Asia, air-borne transmission and its zoonosis nature. Although concerns about disease risks to these macaques have been raised, the role of individual variation, encompassing social network attributes and human exposures, has remained unexplored. To address these questions, this project utilizes non-invasive techniques for sample collection from a population of free-ranging macaques in Thailand. I adopt a network approach to examine the intricate relationship between social attributes and TB infection status. Furthermore, an epidemiological model, Susceptible-Exposed-Infectious-Recovered-Susceptible (SEIRS), is integrated to monitor changes in individuals' disease states and explore hypothetical scenarios of disease spread within social networks, with parameters tailored to each individual.Chapter One investigates the factors driving pathogen infection by identifying infected animals and examining how sociodemographic attributes, combined with interactions with conspecifics, humans, and responses to stress and sickness, influence TB infection patterns within social groups. Notably, it reveals that the likelihood of TB infection increases among individuals with high human interaction and those engaging in less grooming activity. Chapter Two explores the influence of social network positions on TB transmission. By implementing a social network approach to locate infected individuals, this chapter explores the interplay between contact-transmission and social buffering. It highlights the significance of individual macaques' social network positions in their infection status, emphasizing that monkeys with fewer grooming interactions and living periphery are more likely to have TB. Chapter Three employs mathematical modeling within the network to investigate transmission dynamics and the persistence of TB, taking into account variations in transmissibility and latency periods. SEIRS models reveal that over half of the population remains in the latent stage of TB infection. It elucidates that social buffering, specifically the adjustment of the latency period from latency to active TB, plays a pivotal role in explaining the presence of infected individuals in the social network periphery. In contrast, adjusting transmissibility fails to accurately represent observed relationships in this population. Overall, this dissertation aims to uncover the social and demographic factors that influence the acquisition and transmission of TB among free-ranging long-tailed macaques inhabiting human-wildlife interface areas. Understanding the attributes of social network components in wildlife populations at the human-wildlife interface contributes to mitigating infectious disease transmission, reducing zoonotic risks, and promoting the well-being of both humans and wildlife. These insights play a crucial role in clarifying steps to prevent potential future pandemics.

Cognitive ecology investigates how interactions with the environment shape the cognitive abilities of organisms. Studies on humans have emphasized that cognition is selected for under specific environmental conditions to extract information efficiently. More recently this approach has been applied to animals and focuses on how variation within the environment shapes the evolution of cognitive systems. Animals may use certain behavioral styles or cognitive traits to adapt to the amount of variability and predictability in their environment. Variation in resources and environmental complexity are two major factors that drive the diversity of cognitive adaptations seen across animals, as these are often beneficial for specific conditions or allow for adjusting to novel or changing conditions. For example, animals who experience displacement due to rapid urbanization may benefit from enhanced cognitive abilities and/or behavioral flexibility to adjust to those environmental changes quickly.Combining cognitive and urban ecology is particularly interesting because animals often need to consider both predictable and unpredictable elements of human behavior to survive. While many animals can capitalize on the predictable elements of human behavior in the urban environment by avoiding direct interactions with humans, those who can capitalize on more unpredictable sources of variation, such as opportunistic provisioning, may gain an advantage in environments where this type of variation exists in substantial quantities. One way that animals may capitalize on these benefits is by exhibiting traits such as reduced neophobia, enhanced problem-solving abilities, and behavioral flexibility. These traits would allow them to access a wider variety of food resources available in urban spaces and may provide significant fitness advantages. This dissertation explores several aspects of behavioral flexibility ranging from specific, technical quantifications of an individual’s flexibility to solve foraging problems to more holistic or general strategies that individuals may adopt in foraging contexts. Combining experiments from the field and captivity, I explore how individuals innovate (i.e. solve a new problem or apply an old solution to a new problem) and whether they are flexible in their problem-solving behavior. For both the cognitive experiments and behavioral observations, I focused on two closely related species of macaques, rhesus (Macaca mulatta) and long-tailed (Macaca fascicularis). By combining these approaches, I explore both the proximate mechanisms of behavioral flexibility through induced innovation as well as the natural manifestations of flexibility in female foraging behavior. Together, these projects quantify inter-individual differences in foraging behavior and extractive foraging abilities, as well as the role of individual traits in those abilities. Further, these studies provide important insights on the differences in foraging strategies for individuals living in complex and uncertain environments. These insights may be important for understanding the effects of rapid human-induced environmental change and how animals cope with those changes through behavioral diversity and problem-solving.

Interactions between social units are a pervasive aspect of human and animal socioecology, influencing access to crucial resources such as food, safe habitats, and mates, which in turn affect fitness and population structure. Human-induced modifications of animal environments impact various behavioural aspects, including social structure, aggression, affiliation, and movement. Due to rapid urbanization, an increasing number of animal groups now inhabit anthropogenic areas, potentially leading to higher intergroup contact and resulting in intergroup conflict (IGC). Despite extensive research on changes in animal intragroup behaviour, little attention has been paid to how resource modifications and increased group density in anthropogenic areas affect interactions between social units. Moreover, the various human impacts are often conflated, whereas animals might exhibit different responses based on the scale and type of anthropogenic influence. This dissertation will, first, provide a conceptual framework illustrating how multiple scales of anthropogenic influences might lead to corresponding changes in intergroup relationships, either directly or by modifying intragroup behaviour (Chapter 1). This framework is then tested across various levels of socioecological complexity. To examine whether anthropogenic food affects group-level patterns of IGC, I developed an agent-based model called AnthroIGC, which helped uncover patterns of IGC emerging from various combinations of food characteristics such as abundance (number of food sites), depletion (number of items per site), and distribution (clumped vs. dispersed), as well as intragroup social characteristics like cohesion and skew in resource access (chapter 2). Next, using empirical data from three rhesus macaque (Macaca mulatta) groups inhabiting a (peri)urban landscape, I tested the role of sociodemographic attributes such as sex, dominance rank, coalitionary support, and social integration in driving inter-individual differences in participation (chapter 3), finding that males and subordinate individuals engaged in IGC more frequently compared to females and high-ranking females. Moreover, single and multilayer social network analyses revealed that strong coalitionary support connections increased participation in IGI, especially for individuals less integrated into the group in terms of their multilayer connections across different affiliative behaviours. Finally, individuals not only display inter-individual differences but also modify their participation decisions based on the context of IGC. In the final chapter (chapter 4), this thesis explores how various scales of anthropogenic food availability (current availability, long-term availability, and predictability), individual resource access, and the proximate social environment drive participation decisions in male and female rhesus macaques. Using data from 744 instances of IGC, the study finds that both male and female participation is influenced by availability and access to anthropogenic food. However, female participation is more affected by current food availability and differences in relative group size, while males balance both resource and mate access, with their participation patterns emerging as a complex balance between mating seasonality, group size, and the presence of dominant bystanders.This research extends the understanding of a fundamental animal behaviour, that is, interactions between social groups across diverse socioecological conditions and advocates for the extension of existing socioecological theory to human-modified landscapes, using a complex systems approach. Given the prevalence of interactions and conflicts between social units in current and evolutionary human history, studying such behaviour in an equally adaptable species like macaques can provide valuable insights into adaptive decision-making and the evolutionary trajectories of species in the Anthropocene.