Doctoral Dissertation Research: Human disturbance, habituation, and stress responsiveness in wild, endangered primates

As human mobility and populations expand, primates are increasingly exposed to unavoidable, potentially stressful human influences. There is an assumption that apparent tolerance of human presence by primates indicates habituation (primates learn that human presence is not associated with negative consequences), and consequently, primates no longer experience negative effects of stress. These assumptions may be inaccurate or premature; indeed there is evidence that unavoidable, chronic exposure of primates to tourism can be stressful, indicated by behavioral and physiological responses, even in sites active for decades. This dissertation aims to examine these assumptions in Tangkoko Nature Reserve, Sulawesi, Indonesia, by investigating behavioral and physiological responses of wild macaques to the presence of tourists and crop-guarding. It will be the first study to distinguish between chronic and acute stress in wild macaques, making a unique contribution to our understanding of the nature of stress responses in primates and suggesting improved conservation methods for an endangered primate species. The project will also provide training for a female STEM graduate student and both US and Indonesian undergraduate research assistants, and will include local community education and outreach efforts. In this two-year study, the investigators will collect salivary and fecal cortisol data and behavioral data for 12 adult macaques in each of three groups, where groups differ in levels of human interaction. In normal (acute) responses to stress, stress hormones rise, but return to baseline levels within a few hours. However, chronic stress responses (in which stress hormones remain high) can be detrimental to an individual's health and reproductive potential. Thus, the data collected here will shed light on whether primate groups exposed to tourism for decades fully habituate or whether their apparent tolerance masks abnormal stress responses likely to be detrimental to fitness. Due to their close phylogenetic relatedness, this can also enhance our understanding of human stress response. In addition to training and outreach broader impacts, the project will also develop non-invasive field measures of cortisol that can be used by a variety of primate and wildlife researchers.