Document Type


Date of Degree Completion

Spring 2022

Degree Name

Master of Science (MS)


Primate Behavior

Committee Chair

Mary Lee A. Jensvold

Second Committee Member

Lori K. Sheeran

Third Committee Member

J. B. Mulcahy


Visitor effect studies have had inconsistent impacts on animals, due in part to the inability to control for all confounding variables such as time of day, seasonal weather patterns, and so forth. This study represents the first instance where chimpanzee (Pan troglodytes) wounding frequencies were investigated across extensive time periods in the presence and complete absence of visitors, thus eliminating many visitor-related variables. Additional variables were eliminated through the zoo selection process, based on institutional responses to a 29-question survey, providing a novel approach to the question of visitor effects. The aim of this study was to determine if visitors were associated with a change in chimpanzee wound event frequencies across four 51-day time periods, three of which occurred prior to the COVID-19 pandemic, and one occurred during the first wave of the COVID-related zoo closures. We analyzed archival records of 21 chimpanzees housed at three U.S. zoos. Due to the small number of wound events across all study windows, frequencies of “no wound” events were analyzed. Results showed no significant difference between frequencies of “no wound” events while visitors were present or absent, suggesting that chimpanzee welfare, as it relates to wounding, may not be adversely affected by zoo visitors.