Physiological and behavioural responses to habitat fragmentation by black lion tamarins

Habitat fragmentation is one of the major threats hanging over primate populations in South America. Before affecting primates at a population level, environmental perturbations affect the physiology of the individuals. Glucocorticoids (GCs), often referred to as stress hormones, are metabolic hormones which mediate the energetic demands needed to overcome predictable and unpredictable environmental and social challenges. These physiological biomarkers play a key role in enabling individuals to respond to stressors and restore physiological homeostasis. How primates adapt to habitat fragmentation pressures remains poorly understood. The aim of this research is to investigate the physiological and behavioural responses of the endangered black lion tamarins (Leontopithecus chrysopygus) living in the Brazilian Atlantic Forest, a habitat particularly affected by fragmentation. The three specific objectives of this research are: (1) reviewing the effect of anthropogenic habitat disturbance on the well-being of primates, (2) analysing variation in chronic stress of tamarins in different forest fragment quality, and (3) relating transient stress levels to behavioural patterns. The first objective will consist of an extensive bibliographic research to identify how habitat disturbance variables affect primate well-being. Regarding physiological markers, we will use two different matrixes to measure GC concentrations. First, GC levels in hair samples (hair cortisol concentrations-HCC) will provide us with information on long term adrenocortical activity, recounting the animal’s chronic stress levels. Second, faecal GC levels will inform us about short term exposure to stress unfolding the animal’s daily fluctuations. Consequently, to approach the second objective, we will compare habitat quality with the HCCs of six tamarin groups living in fragments of different quality. For the third objective, we will compare faecal GC levels with behaviour patterns collected during daily follow-ups of three tamarin groups. This project will be conducted as a joint-PhD between ULiège and the Sao Paulo State University (Brazil). Evaluating stress levels in primate populations living in fragmented landscapes can shed light on how primates respond to such habitat perturbations and how significant it is for their survival.