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Primate social organizations, or grouping patterns, vary significantly across species. Behavioral strategies that allow for flexibility in grouping patterns offer a means to reduce the costs of group living. Chimpanzees (Pan troglodytes) have a fission‐fusion social system in which temporary subgroups (“parties”) change in composition because of local socio‐ecological conditions. Notably, western chimpanzees (P. t. verus) are described as showing a higher degree of bisexual bonding and association than eastern chimpanzees, and eastern female chimpanzees (P. t. schweinfurthii) are thought to be more solitary than western female chimpanzees. However, reported comparisons in sociality currently depend on a small number of study groups, particularly in western chimpanzees, and variation in methods. The inclusion of additional communities and direct comparison using the same methods are essential to assess whether reported subspecies differences in sociality hold in this behaviorally heterogeneous species. We explored whether sociality differs between two communities of chimpanzees using the same motion‐triggered camera technology and definitions of social measures. We compare party size and composition (party type, sex ratio) between the western Gahtoy community in the Nimba Mountains (Guinea) and the eastern Waibira community in the Budongo Forest (Uganda). Once potential competition for resources such as food and mating opportunities were controlled for, subspecies did not substantially influence the number of individuals in a party. We found a higher sex‐ratio, indicating more males in a party, in Waibira; this pattern was driven by a greater likelihood in Gahtoy to be in all‐female parties. This finding is the opposite of what was expected for eastern chimpanzees, where female‐only parties are predicted to be more common. Our results highlight the flexibility in chimpanzee sociality, and caution against subspecies level generalizations.

1. Studying animal behaviour allows us to understand how different species and individuals navigate their physical and social worlds. Video coding of behaviour is considered a gold standard: allowing researchers to extract rich nuanced behavioural datasets, validate their reliability, and for research to be replicated. However, in practice, videos are only useful if data can be efficiently extracted. Manually locating relevant footage in 10,000 s of hours is extremely time-consuming, as is the manual coding of animal behaviour, which requires extensive training to achieve reliability. 2. Machine learning approaches are used to automate the recognition of patterns within data, considerably reducing the time taken to extract data and improving reliability. However, tracking visual information to recognise nuanced behaviour is a challenging problem and, to date, the tracking and pose-estimation tools used to detect behaviour are typically applied where the visual environment is highly controlled. 3. Animal behaviour researchers are interested in applying these tools to the study of wild animals, but it is not clear to what extent doing so is currently possible, or which tools are most suited to particular problems. To address this gap in knowledge, we describe the new tools available in this rapidly evolving landscape, suggest guidance for tool selection, provide a worked demonstration of the use of machine learning to track movement in video data of wild apes, and make our base models available for use. 4. We use a pose-estimation tool, DeepLabCut, to demonstrate successful training of two pilot models of an extremely challenging pose estimate and tracking problem: multi-animal wild forest-living chimpanzees and bonobos across behavioural contexts from hand-held video footage. 5. With DeepWild we show that, without requiring specific expertise in machine learning, pose estimation and movement tracking of free-living wild primates in visually complex environments is an

Postings on social media on Twitter (now X), BioAnthropology News (Facebook), and other venues, as well as recent publications in prominent journals, show that primatologists, ecologists, and other researchers are questioning the terms “Old World” and “New World” due to their colonial implications and history. The terms are offensive if they result in erasing Indigenous voices and history, ignoring the fact that Indigenous peoples were in the Americas long before European colonization. Language use is not without context, but alternative terminology is not always obvious and available. In this perspective, we share opinions expressed by an international group of primatologists who considered questions about the use of these terms, whether primatologists should adjust language use, and how to move forward. The diversity of opinions provides insight into how conventional terms used in primatological research and conservation may impact our effectiveness in these domains.

We respond to the commentary by Tennie and Call (2023) on the article by Koops et al. (2022) in Nature Human Behaviour titled ‘Field experiments find no evidence that chimpanzee nut cracking can be independently innovated.’ Koops et al. (2022) showed that chimpanzee nut cracking is not a so-called ‘latent solution.’ Chimpanzees (Pan troglodytes verus) in the Nimba Mountains (Guinea) did not crack nuts when presented with nuts and stones in ecologically valid field experiments. In their Commentary, Tennie and Call (2023) argued that the experiments were inconclusive for two reasons: 1) the chimpanzees were not motivated to treat the nuts as food, and 2) the chimpanzees were not within the appropriate ‘sensitive learning period.’ In our response, we argue that Tennie and Call (2023) incorrectly use the term ‘motivation’ to mean ‘willingness to eat the nut’, which requires existing knowledge of the edibility of the nuts. We also point out that it is unnatural and uninformative to inject nuts with honey to motivate the chimpanzees to eat them, as suggested by Tennie and Call (2023). Finally, we highlight that Koops et al. (2022) tested appropriately aged subjects (N=32 immatures). Moreover, we argue that there is no evidence to suggest that there is a strictly sensitive learning period restricted to juvenility. Finally, we emphasize the need for researchers doing experiments in captivity to visit their study species in the wild, and for field researchers to be involved in efforts to design ecologically valid experiments in captivity.