Chimpanzee Activity and Behavioral Diversity Extends Across 24 Hours in Both Captive and Wild Settings.

Studying nocturnal behavior is crucial for understanding the full scope of a species' behavioral flexibility so as to inform the conservation of wild populations and the care of captive individuals. However, this aspect of primate behavior is understudied, especially in great apes, which exhibit some of the widest documented behavioral diversity and flexibility. Our investigation is among the first to systematically compare the 24 h activity patterns and behavioral activities of captive chimpanzees (Saint Louis Zoo, USA) with those of wild chimpanzees (three sites across the Nouabalé-Ndoki National Park in the Republic of Congo) and a published data set of the nocturnal behavior of all chimpanzee subspecies. Furthermore, we examined the influence of human activity and changes to the group's composition on the activity patterns and nocturnal behaviors of the zoo-living chimpanzees. Our results reveal that the zoo-living chimpanzees exhibit significantly different activity patterns compared to their wild counterparts, with increased nocturnal activity (particularly in the early morning) and more observations of feeding and social behaviors at night. Additionally, the absence of human visitors and a change in the group's composition were found to influence these activity patterns. These findings underscore the importance of integrating more holistic approaches to captive primate care and wild primate conservation. This study also highlights the immense potential of implementing remote monitoring technology, such as video camera traps, across contexts. Such data that extend across contexts benefit not only the captive and wild great apes but also provide opportunities for caregivers, conservation managers, and students who are involved in these collaborative initiatives.