Patterns of Behaviour, Group Structure and Reproductive Status Predict Levels of Glucocorticoid Metabolites in Zoo-Housed Ring-Tailed Lemurs, Lemur catta

Abstract

In ring-tailed lemurs, Lemur catta, the factors modulating hypothalamic-pituitary-adrenal (HPA) activity differ between wild and semi-free-ranging populations. Here we assess factors modulating HPA activity in ring-tailed lemurs housed in a third environment: the zoo. First we validate an enzyme immunoassay to quantify levels of glucocorticoid (GC) metabolites in the faeces of L. catta. We determine the nature of the female-female dominance hierarchies within each group by computing David's scores and examining these in relation to faecal GC (fGC). Relationships between female age and fGC are assessed to evaluate potential age-related confounds. The associations between fGC, numbers of males in a group and reproductive status are explored. Finally, we investigate the value of 7 behaviours in predicting levels of fGC. The study revealed stable linear dominance hierarchies in females within each group. The number of males in a social group together with reproductive status, but not age, influenced fGC. The 7 behavioural variables accounted for 68% of the variance in fGC. The amounts of time an animal spent locomoting and in the inside enclosure were both negative predictors of fGC. The study highlights the flexibility and adaptability of the HPA system in ring-tailed lemurs.

Individual, social, and environmental factors affecting salivary and fecal cortisol levels in captive pied tamarins (Saguinus bicolor)

“…Our study might have yielded different relationships between cortisol and social rank under different social or environmental conditions such as following a birth or aggression. in contrast to other primate studies in which variations in group composition such as group size (Pride, 2005) or number of males in a group (Smith, McCusker, Stevens & Elwood, 2015) have been shown to have a significant impact on cortisol levels, we found little influence of group composition on cortisol levels in either saliva or feces.…”