Behavioral Implications of the Complete Absence of Guests on a Zoo-Housed Gorilla Troop

SIMPLE SUMMARY: The welfare of animals in human care should be taken into consideration by both the scientific community and members of the public who are able to view animals in a zoo setting. One component of individual welfare is how groups of animals and the individuals within groups may be affected by the presence of zoo guests. At the Buffalo Zoo in New York, we studied the behavioral differences of six gorillas in two conditions: heavy guest presence and the complete absence of guests. We found few significant behavioral differences between the conditions, with the greatest behavioral change observed in the adult silverback male. We stress the importance of not over-generalizing our findings, and suggest an inter-institutional study of the nuanced ways that zoo guests interact with gorillas in managed care. ABSTRACT: Research conducted on the effects that zoo visitors have on primate behavior has yielded inconsistent patterns. This study aims to contribute to the growing body of literature regarding visitor effects on zoo-housed primate’s activity budgets, with the purpose of quantifying the behavioral variability under two conditions: guest presence and guest absence. Due to the COVID-19 pandemic, many zoos were closed to the public for varying lengths of time. The Buffalo Zoo was closed to guests for an 18-week period including the summer of 2020, which allowed us to effectively control for zoo guest presence. This case report compares data on the zoo’s gorilla troop from the same time period in 2019. We found inconsistent results, similar to prior studies conducted with zoo-housed gorilla troops. Most gorillas were observed foraging less and exhibiting more inactivity in 2020, whereas the adult male silverback showed the opposite pattern. Abnormal or undesirable behaviors were performed less frequently when guests were absent however, these differences were not significant. We encourage others to compare behavior patterns during the pandemic shutdown to add to our knowledge base of visitor effects. We suggest that researchers do not try and generalize their individual and troop results to the entire population of gorillas in managed care, as both intrinsic and extrinsic factors contribute to individual differences in behavioral response.