Things Are Not Always What They Seem: Combining Multiple Approaches to Understand Possible Impacts of Visitors on a...

A zoo-housed male Francois langur (Trachypithecus francoisi) displayed frequent territorial behaviors toward visitors, generating concern he may be experiencing negative visitor effects. After visual and physical barriers were unsuccessful at reducing these behaviors, he was prescribed anxiolytic medication. Our objective was to understand the effects of visitors on this male after reaching a therapeutic dose of anxiolytic medication. We analyzed effects of visitor presence (whether the exhibit was open or closed to the public) and number (weekdays vs. weekends, gate count). Behavior and physiological biomarkers were analyzed using linear and generalized linear models, respectively. Behaviors included time spent engaged in vigilance as well as rates of fast locomotion displays, leaping-and-hitting the barrier, grimacing, and rough scratching. Biomarkers included cortisol, dehydroepiandrosterone-sulfate (DHEA-S), the cortisol/DHEA-S ratio, testosterone, and immunoglobulin A (IgA). The langur performed more leap-and-hit barrier when the exhibit was open (β = 0.750, SE = 0.282, p = 0.013), on weekends (β = 0.618, SE = 0.277, p = 0.034), and with higher gate counts (β < 0.001, SE < 0.001, p = 0.004). Initially positive associations between rough scratching and visitor number were not significant when accounting for temperature. Cortisol/DHEA-S ratios trended toward significantly lower when the exhibit was open and IgA showed evidence of a potential dither effect, although the latter is ambiguous. No other behaviors or biomarkers were associated with visitor-related variables. We also compared behavior and physiology before and during anxiolytic medication as well as relationships between behaviors and biomarkers. Taken together, the balance of visitor effects appears neutral. Furthermore, considering other evidence, the langur does not appear to have diminished well-being.