Keeper effect: Animals are more active in the presence of their caretakers.

Zookeepers are the primary caretakers of animals, providing daily care through frequent and close interactions. From the animal's perspective, most of these daily interactions are likely to have positive outcomes. With consistent and reliable interactions, a human-animal relationship is expected to develop. Our aim of this study was to investigate if the presence of the primary keeper in the public viewing area of zoo exhibits impacts the behavior of animals. We observed the behavior of 15 individuals of six species in the presence and absence of their primary keeper. Overall, we observed animals being more active in their keeper's presence than when the keeper was not present. When we considered if the keeper was nearby around times of offered opportunities to animals (e.g., feeding, enrichment, and training), our results showed that animals were equally as active when the keeper was present before an opportunity and when no opportunity was offered. These equal activity levels imply that the keeper is a cue for a forthcoming event to the animals, which reflects anticipatory behavior. Overall, we demonstrate that keeper presence is an environmental context in which animals behave differently than in keeper absence.