Behavioral Responses of Zoo Animals During a Total Solar Eclipse in the Absence of Visitors

Our understanding of the impact of solar eclipse events on animal behaviors is mostly based on anecdotal reports, and rigorous scientific studies are scarce. On April 8, 2024, a significant portion of North America witnessed a rare total solar eclipse. This was a unique chance to study how animals in zoological institutions react to unpredictable and sudden environmental changes. Although based on a short-duration event (approximately 3 h in total and 1-4 min of total eclipse), such an event is an opportunity to carry out comparative studies on animal behavior and cognition. We compared the behavior and space use of animals during the eclipse to the same time period on days before and after the eclipse (baseline). While most species showed little response, Japanese macaques showed a significant and noticeable response by reducing their activity level and moving up higher on branches in their habitat. They returned to their normal behavior when the light intensity came back to normal. Zebras reacted with increased activity level and some signs of stress that lasted beyond totality. Incidentally, we found that the observers' subjective appraisal of behavioral responses does not fully match the data collected, emphasizing the importance of standardized protocols and training in animal behavior studies. As the zoo was closed to visitors during the observations, our study allows for a better understanding of animal behavioral reactions to total eclipse events, without the confusing effect of surrounding humans' reactions.