Assessment of Stress in Captive Monkeys Using Faecal Cortisol Levels

Abstract

Captive monkeys in zoo environments face various stressors that could significantly impact their
health, behaviour, and welfare. Continuous stay in captive settings with attendant human visitors
could trigger apprehension and other stressors in monkeys Non-invasive monitoring of stress
through faecal cortisol metabolites (FCMs) provides a valuable tool for assessing adrenocorticoid
activity without the stressor effects associated capture and restraint procedures. This study aim is
to determine the baseline values of faecal glucocorticoid metabolites for monkeys in captivity at
the Federal University of Agriculture, Abeokuta (FUNAAB) Zoo Park, and to evaluate the effects
of species, sex, and human visitors on cortisol concentrations over a four-week period. Twelve
monkeys representing five species (Papio anubis, Erythrocebus patas, Cercopithecus nictitans, C.
mona, and C. aethiops) were monitored over four weeks with faecal samples collected at seven-
day intervals. Samples were dried, extracted using 80% methanol, and analysed using Enzyme-
Linked Immunosorbent Assay (ELISA). Statistical analyses included repeated measures ANOVA,
Friedman test, one-way ANOVA, and independent t-tests. Significant temporal variation in cortisol
levels was observed across the four-week study period (P-value= 0.012). There was significant
differences in stress levels amongst species studied (p-value= 0.015), Visitors exposure indices
showed a non-significant trend. (p-value= 0.087), gender difference was also non- significant (p-
value= 0.257). This study demonstrates that stress assessment in captive monkeys requires
longitudinal monitoring rather than single-point measurements, as cortisol levels change
significantly over time. Species-specific differences in stress responses highlight the need for
tailored welfare protocols. The result of the study indicates that predictable human interactions
may be less stressful to monkeys than inconsistent and unpredictable moderate exposures to
anthropogenic activities.