Search

Human population growth and anthropogenic activities are exacerbating pressures on biodiversity globally. Land conversion is aggravating habitat fragmentation and non-human primates are increasingly compelled to live in forest-agricultural mosaics. In Sierra Leone, more than half of the wild chimpanzee population (Pan troglodytes verus) occurs outside protected areas and competes for resources with farmers. Our study area, in the Moyamba district in south-western Sierra Leone, is practically devoid of forest and is dominated by cultivated and fallow fields, swamps and mangroves. In this region, traditional slash-and-burn agriculture modifies annually the landscape, sparing swamps and mangroves and semi-domesticated oil palms (Elaeis guineensis). This study aimed to explore ecological and anthropogenic factors influencing chimpanzee relative abundance across this highly degraded and human-impacted landscape. Between 2015 and 2016, we deployed 24 camera traps systematically across 27 1.25x1.25 km grid cells. Cameras were operational over a period of 8 months. We used binomial iCAR models to examine to what extent anthropogenic (roads, settlements, abandoned settlements and human presence) and habitat variables (swamps, farmland and mangroves) shape chimpanzee relative abundance. The best model explained 43.16% of the variation with distance to roads and swamps emerging as the best predictors of chimpanzee relative abundance. Our results suggest that chimpanzees avoid roads and prefer to maintain proximity to swamps. There was no significant effect of settlements, abandoned settlements, mangroves or human presence. It appears that chimpanzees do not avoid areas frequented by people; although, our findings suggest temporal avoidance between the two species. We highlight the importance of studying chimpanzee populations living in anthropogenic habitats like agricultural-swamp matrixes to better understand factors influencing their distribution and inform conservation pla

Estimating population size and density of a population of a species are essential to inform conservation management strategies and land-use planning. However, some landscapes dominated by fallow areas pose great challenges when it comes to traditional transect surveys. Unmanned aerial vehicle (UAV) and camera trapping technologies have demonstrated great potential when it comes to surveying wildlife. In this study, we employed camera trapping in combination with spatially explicit capture-recapture (SECR) models for estimating chimpanzee (Pan troglodytes verus) numbers in a non-protected area in the Moyamba district in south-western Sierra Leone, ca. 90 square kilometres. We estimated trapping rate per 1.25 km square grids across the target area based on a systematic layout of camera traps (N=30). In this environment practically devoid of forest, chimpanzees only nest in semi-domesticated oil palms (Elaeis guineensis) which are prevalent in the landscape. Due to the nesting specificity of the chimpanzees in this area, we were readily able to estimate nest density per grid and across the entire target area using drone imagery based on a sampling regime of 3 missions (200 meter square each) within each sample grid. We compared these abundance estimates with those generated from the SERC model and individual chimpanzee identification. Our study reveals that drone imagery data yields equivalent results and can effectively estimate chimpanzee population parameters across such degraded landscapes. The application of UAV technology in such environments can serve to inform conservation and land-use planning for chimpanzees, especially in areas prone to infrastructure and industrialized agricultural development.

The majority of the critically endangered chimpanzees (Pan troglodytes verus) occur outside protected areas. Ensuring their long-term survival in such areas implies addressing people-chimpanzee coexistence challenges. Using origin data of confiscated chimpanzees from two chimpanzee sanctuaries in West Africa, i.e. the Chimpanzee Conservation Center (CCC), Guinea and the Tacugama Chimpanzee Sanctuary, Sierra Leone, and forest loss data from 2001 to 2015, we highlight how deforestation exacerbates interactions between people-chimpanzees and acts as a driver for the killing and capture of chimpanzees in the region. Finally, we present results from a systematic camera trapping survey (24 camera traps deployed across 27 1.25x1.25 km grids) conducted in the Moyamba district in south-western Sierra Leone in an area dominated by subsistence agricultural activities and practically devoid of forest. We employed a hierarchical Bayesian framework accounting for spatial autocorrelation to explore ecological and anthropogenic factors influencing chimpanzee relative abundance across the landscape. Our findings revealed that chimpanzees in such landscapes, where people are relatively tolerant of their presence, tend to avoid roads, including untarmacked secondary roads, and prefer to range in close proximity to more intact habitats such as swamps. Unexpectedly, they showed no preference for abandoned settlements where fruit orchard persist. Finally, although chimpanzees in this area did not avoid human settlements or areas frequented by people, areas of spatial overlap between the two species revealed temporal divergence in utilization. Altogether, these studies emphasize the urgent need to understand better factors that influence chimpanzee abundance and distribution outside protected areas, especially in the context of the rate of forest loss, and for aligning land use planning and infrastructure development to serve both the needs of people and chimpanzees.

Human population growth and anthropogenic activities are exacerbating pressures on biodiversity globally. Land conversion is aggravating habitat fragmentation and non-human primates are increasingly compelled to live in forest-agricultural mosaics. In Sierra Leone, more than half of the wild chimpanzee population (Pan troglodytes verus) occurs outside protected areas and competes for resources with farmers. Our study area, in the Moyamba district in south-western Sierra Leone, is practically devoid of forest and is dominated by cultivated and fallow fields, swamps and mangroves. In this region, traditional slash-and-burn agriculture modifies annually the landscape, sparing swamps and mangroves and semi-domesticated oil palms (Elaeis guineensis). This study aimed to explore ecological and anthropogenic factors influencing chimpanzee relative abundance across this highly degraded and human-impacted landscape. Between 2015 and 2016, we deployed 24 camera traps systematically across 27 1.25x1.25 km grid cells. Cameras were operational over a period of 8 months. We used binomial iCAR models to examine to what extent anthropogenic (roads, settlements, abandoned settlements and human presence) and habitat variables (swamps, farmland and mangroves) shape chimpanzee relative abundance. The best model explained 43.16% of the variation with distance to roads and swamps emerging as the best predictors of chimpanzee relative abundance. Our results suggest that chimpanzees avoid roads and prefer to maintain proximity to swamps. There was no significant effect of settlements, abandoned settlements, mangroves or human presence. It appears that chimpanzees do not avoid areas frequented by people; although, our findings suggest temporal avoidance between the two species. We highlight the importance of studying chimpanzee populations living in anthropogenic habitats like agricultural-swamp matrixes to better understand factors influencing their distribution and inform conservation pla

The oil palm (Elaeis guineensis) is a common and sometimes predominant feature of many West African landscapes. In countries such as Guinea and Sierra Leone, wild or feral oil palms often dominate fallow and cultivated fields, as well as abandoned or recent human settlements; they also thrive in gallery and secondary forests. We will highlight here the extent to which wild chimpanzees differ in their cultural use and dependence on the oil palm. Across Africa, many wild chimpanzee communities make use of oil palm parts for feeding and nesting purposes. People also traditionally depend on the oil palm for a range of purposes including among others cooking, soap and wine making and construction for both subsistence and commercial purposes. Increasing global demand for oil palm is rapidly changing the landscape to include both large and small scale plantations. We used data gathered as part of a nationwide survey of chimpanzees as well as from more focused studies in areas reporting high levels of human-wildlife interactions to assess 1) the extent of competition in the use of oil palm between people, chimpanzees and other wildlife and 2) relative perceptions concerning competition for the oil palm between chimpanzees and people. We discuss the implication of these patterns with respect to land use management and agricultural development in West Africa.