Inter-community behavioural variation confirmed through indirect methods in four neighbouring chimpanzee communities in Cantanhez NP, Guinea-Bissau

Culture, while long viewed as exclusively human, has now been demonstrated across diverse taxa and contexts. However, most animal culture data are constrained to well-studied, habituated groups. This is the case for chimpanzees, arguably the most 'cultural' non-human species. While much progress has been made charting wild chimpanzees' cultural repertoire, large gaps remain in our knowledge of the majority of the continent's chimpanzees. Furthermore, few studies have compared neighbouring communities, despite such comparisons providing the strongest evidence for culture, and few have studied communities living in anthropogenic habitats although their culture is in imminent danger of disappearing. Here we combine direct, indirect and remote methods, including camera traps, to study, over 2 years, four unhabituated neighbouring chimpanzee communities inhabiting human-impacted habitats in Cantanhez NP, Guinea-Bissau. From traces collected during 1089 km of reconnaissance walks and 4197 videos from 56 camera trap locations, we identified 18 putative cultural traits. These included some noteworthy novel behaviours for these communities, and behaviours possibly new to the species. We created preliminary behavioural profiles for each community, and found inter-community differences spanning tool use, communication, and social behaviour, demonstrating the importance of comparing neighbouring communities and of studying previously neglected communities including those inhabiting anthropogenic landscapes.

Social-Ecological Interactions Influencing Primate Harvest: Insights From Madagascar

Globally, non-human primates face mounting threats due to unsustainable harvest by humans. There is a need to better understand the diverse drivers of primate harvest and the complex social-ecological interactions influencing harvest in shared human-primate systems. Here, we take an interdisciplinary, systems approach to assess how complex interactions among primate biological and ecological characteristics and human social factors affect primate harvest. We apply our approach through a review and synthesis of the literature on lemur harvest in Madagascar, a country with one of the highest primate species richness in the world coupled with high rates of threatened primate species and populations in decline. We identify social and ecological factors affecting primate harvest, including the characteristics of lemurs that may make them vulnerable to harvest by humans; factors describing human motivations for (or deterrents to) harvest; and political and governance factors related to power and accessibility. We then discuss social-ecological interactions that emerge from: (1) the prevalence of informal institutions (e.g., cultural taboos), (2) adoption of human predatory strategies, (3) synergies with habitat use and habitat loss, and (4) interactions among regional- and local-scale factors (multi-level interactions). Our results illustrate that social-ecological interactions influencing lemur harvest in Madagascar are complex and context-specific, while influenced by a combination of interactions between species-specific characteristics and human social factors. These context-specific interactions may be also influenced by local-level cultural practices, land use change, and effects from regional-level social complexities such as political upheaval and food insecurity. We conclude by discussing the importance of identifying and explicitly accounting for nuances in underlying social-ecological systems and putting forth ideas for future research on primate harvest in shared human-primate systems, including research on social-ecological feedbacks and the application of Routine Activities Theory.

Developing an Evidence-Based Coexistence Strategy to Promote Human and Wildlife Health in a Biodiverse Agroforest Landscape

Agroforest mosaics represent one of the most extensive human-impacted terrestrial systems worldwide and play an increasingly critical role in wildlife conservation. In such dynamic shared landscapes, coexistence can be compromised if people view wildlife as a source of infectious disease. A cross-disciplinary One Health knowledge base can help to identify evolving proponents and threats to sustainable coexistence and establish long-term project goals. Building on an existing knowledge base of human–wildlife interactions at Cantanhez National Park (NP), Guinea-Bissau, we developed a causal pathway Theory-of-Change approach in response to a newly identified disease threat of leprosy in the Critically Endangered western chimpanzee (Pan troglodytes verus). The goals of our project are to improve knowledge and surveillance of leprosy in humans and wildlife and increase capacity to manage human–wildlife interactions. We describe the core project activities that aim to (1) quantify space use by chimpanzees across Cantanhez NP and determine the distribution of leprosy in chimpanzees; (2) understand the health system and local perceptions of disease; and (3) identify fine-scale risk sites through participatory mapping of resources shared by humans and chimpanzees across target villages. We discuss the development of a biodiversity and health monitoring programme, an evidence-based One Health campaign, and a One Health environmental management plan that incorporates the sharing of space and resources, and the disease implications of human–non-human great ape interactions. We demonstrate the importance of multi-stakeholder engagement, and the development of strategy that fully considers interactions between people, wildlife, and the environment.

Leprosy in wild chimpanzees

Humans are considered as the main host for Mycobacterium leprae1, the aetiological agent of leprosy, but spillover has occurred to other mammals that are now maintenance hosts, such as nine-banded armadillos and red squirrels2,3. Although naturally acquired leprosy has also been described in captive nonhuman primates4-7, the exact origins of infection remain unclear. Here we describe leprosy-like lesions in two wild populations of western chimpanzees (Pan troglodytes verus) in Cantanhez National Park, Guinea-Bissau and Taï National Park, Côte d'Ivoire, West Africa. Longitudinal monitoring of both populations revealed the progression of disease symptoms compatible with advanced leprosy. Screening of faecal and necropsy samples confirmed the presence of M. leprae as the causative agent at each site and phylogenomic comparisons with other strains from humans and other animals show that the chimpanzee strains belong to different and rare genotypes (4N/O and 2F). These findings suggest that M. leprae may be circulating in more wild animals than suspected, either as a result of exposure to humans or other unknown environmental sources.

First Evidence of Chimpanzee Extractive Tool Use in Cantanhez, Guinea-Bissau: Cross-Community Variation in Honey Dipping

Wild chimpanzee tool use is highly diverse and, in many cases, exhibits cultural variation: tool-use behaviours and techniques differ between communities and are passed down generations through social learning. Honey dipping – the use of sticks or leaves to extract honey from hives – has been identified across the whole species’ range. Nonetheless, there seems to be marked variation in honey dipping at a species level, with most descriptions originating from central Africa, and involving the use of complex tool sets, or even multifunctional tools. In West Africa, while honey consumption is common, in most cases tools are not used. We document, for the first time, the use of honey dipping tools in unhabituated chimpanzee (Pan troglodytes verus) communities at Cantanhez National Park (CNP), Guinea-Bissau. Over a 23-month period we employed a combination of direct (camera traps, n = 1944 camera trap days) and indirect (1000km of reconnaissance walks, collection of abandoned tools) methods to study four neighbouring communities in central CNP. Fluid dipping tools were found in three of the four communities; here we analyse 204 individual stick tools from the 70 tool-use ateliers found. In addition to documenting individual tool dimensions and raw materials, we adopt methods from primate archaeology to describe the typology of different tools based on use-wear patterns. We describe differences in tools used for different honey types, between communities, and tools and tool kits that show an unexpected degree of complexity. Our data also suggest the use of tool sets, i.e., tools with different functions used sequentially toward the same goal; as well as possible multifunction tools (pounding and dipping), never before described for western chimpanzees. Our study fills gaps in our knowledge of the wild chimpanzee cultural repertoire and highlights how chimpanzee tool manufacture and use can vary even at local scales.

Chimpanzees balance resources and risk in an anthropogenic landscape of fear

Human-wildlife coexistence is possible when animals can meet their ecological requirements while managing human-induced risks. Understanding how wildlife balance these trade-offs in anthropogenic environments is crucial to develop effective strategies to reduce risks of negative interactions, including bi-directional aggression and disease transmission. For the first time, we use a landscape of fear framework with Bayesian spatiotemporal modelling to investigate anthropogenic risk-mitigation and optimal foraging trade-offs in Critically Endangered western chimpanzees (Pan troglodytes verus). Using 12 months of camera trap data (21 camera traps, 6722 camera trap days) and phenology on wild and cultivated plant species collected at Caiquene–Cadique, Cantanhez National Park (Guinea-Bissau), we show that humans and chimpanzees broadly overlapped in their use of forest and anthropogenic parts of the habitat including villages and cultivated areas. The spatiotemporal model showed that chimpanzee use of space was predicted by the availability of naturalised oil-palm fruit. Chimpanzees used areas away from villages and agriculture more intensively, but optimised their foraging strategies by increasing their use of village areas with cultivated fruits when wild fruits were scarce. Our modelling approach generates fine-resolution space–time output maps, which can be scaled-up to identify human-wildlife interaction hotspots at the landscape level, informing coexistence strategy.