Department of Anthropology, The Ohio State University
Friday 207, Plaza Level
Fecal glucocorticoid metabolites (e.g., cortisol) are a valuable non-invasive source of information on individual levels of physiological stress. However, using them to evaluate stress levels among females can be problematic in species that do not show overt signs of reproductive condition because concentrations of reproductive hormones can affect cortisol concentrations. For example, high concentrations of estradiol during pregnancy may promote an increase in glucocorticoids and associated binding factors. Here, we examine the efficacy of using fecal glucocorticoid metabolites as an indicator of stress and whether estradiol is a potential confound of such measurements in both wild (El Zota, Costa Rica) and captive (Brookfield Zoo, Illinois) black-handed spider monkeys (Ateles geoffroyi). First, fecal cortisol concentrations were measured from captive female spider monkeys before and after a veterinary exam. All females exhibited elevated cortisol concentrations after this stressful experience, though concentrations were highly variable among individuals in both conditions. Second, we examined the relationship between cortisol and estradiol concentrations in captive and wild females. In the captive samples all females were cycling and cortisol and estradiol levels were not related (N=22, r=0.177 two-tailed p=0.431). However, in the wild sample, which included nursing, cycling, and pregnant females, cortisol and estradiol were positively correlated (N=24, r=0.700, two-tailed p<0.001). Thus, we demonstrate the need to examine estradiol concentrations when measuring cortisol concentrations among females of unknown reproductive condition. We are currently examining how cortisol concentrations vary among female spider monkeys based on social and environmental factors as well as age, rank and reproductive state.
Funding from The Ohio State University chapter of Sigma Xi and the Wenner-Gren Foundation