The effect of a nighttime zoo event on spider monkey (Ateles geoffroyi) behavior

The relationship between zoo animals, particularly nonhuman primates, and visitors is complex and varies by species. Adding complexity to this relationship is the trend for zoos to host events outside of normal operating hours. Here, we explored whether a late-night haunted-house style event influenced the behavior of spider monkeys. We conducted behavioral observations both on event nights and nights without the event. The spider monkeys were active and outside more frequently on event nights compared to the control nights indicating that their typical nighttime behavior was altered. However, it is difficult to definitively conclude whether the behavioral changes were a result of the event being aversive or enriching. Our findings suggest that zoos should conduct behavioral observations of and collect physiological data from their animals, especially if they are sensitive to environmental changes, when implementing new events, including those occurring outside of normal operating hours to ensure high levels of animal welfare.