The effects of Zoo Lights on animal welfare: A case study of great Indian hornbills at Denver Zoo

Popular evening events, such as Zoo Lights, increase the exposure of animals in managed care to stressors such as artificial light and noise, which may alter their behavior and negatively affect animal well‐being. The pair of great Indian hornbills (Buceros bicornis) at Denver Zoo provided an opportunity to study the impacts of these stressors because their exhibit was open every evening during Zoo Lights 2017. We expected the hornbills to display increased aggressive behaviors during Zoo Lights due to more exposure to stressors compared to the periods before and after the holiday event. Alternatively, if behavioral changes were associated with hornbills' breeding season which runs from December−March, we expected the hornbills to engage in more affiliative behaviors, and to increase conspecific and nest proximity, during and after Zoo Lights compared to before it due to the onset and progression of the breeding season. The hornbills did not engage in significantly more aggressive behavior during Zoo Lights than before or after it. By contrast, the hornbills engaged in significantly more affiliative behaviors and increased conspecific proximity during and after Zoo Lights compared to before the event. These results are consistent with the timing of the hornbills' breeding season and not with the increased exposure to stressors during Zoo Lights. This case study provides an early step in assessing the impact of Zoo Lights on animals whose exhibits are part of these holiday events. Studies like this will help inform best practices for Zoo Lights events such that they are positive experiences for the zoo, visitors, and animals. Proportions of male aggressive and affiliative behaviors before, during, and after Zoo Lights. The odds of the male engaging in aggressive behaviors did not significantly differ across the three time‐periods. The odds of engaging in affiliative behaviors significantly increased after Zoo Lights compared to before and during Zoo Lights, and significantly increased during Zoo Lights compared to before it. *Significant difference when α