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The West African chimpanzee is critically endangered (CR). From 1990 to 2007, Ivory Coast lost 90% of its population to habitat destruction and poaching. In order to effectively implement conservation measures, we need to determine the status of any remaining populations in the country. The chimpanzee population of Comoe National Park (CNP) was assumed to have been severely depleted following the politico-military crisis of 2002–2011. Surveys in 2007, 2010, 2012, and 2014 failed to find significant evidence of chimpanzees in the park, leading managers to believe that no sustainable population was left. To evaluate status and distribution of chimpanzees in CNP, in 2015 we conducted a stratified survey in our study area in the southwest of the park. Over the next 3 years, we conducted recce walks in the north, east, and center of the park, and in 2017 we collected additional data on distribution of chimpanzees during the full park survey for elephants. Additionally, for the first time in northern Ivory Coast, we carried out a local nest decay study. In our main study area, we estimated a density of 0.14 weaned chimpanzees/km2, with an abundance of 127 (92–176) weaned chimpanzees, representing a sustainable population in CNP. We identified 123 individual chimpanzees via parallel camera-trap survey. We discovered a resident chimpanzee population to the east of the Comoe River, an area previously assumed devoid of chimpanzees. This study confirms the viability of a population key for the conservation of Western chimpanzee. We stress the importance of concentrating stratified surveys in potential wildlife habitat to determine the distribution of this and other cryptic threatened species.

Paleoclimate reconstructions have enhanced our understanding of how past climates have shaped present-day biodiversity. We hypothesize that the geographic extent of Pleistocene forest refugia and suitable habitat fluctuated significantly in time during the late Quaternary for chimpanzees (Pan troglodytes). Using bioclimatic variables representing monthly temperature and precipitation estimates, past human population density data, and an extensive database of georeferenced presence points, we built a model of changing habitat suitability for chimpanzees at fine spatio-temporal scales dating back to the Last Interglacial (120,000 BP). Our models cover a spatial resolution of 0.0467 degrees (approximately 5.19 km(2) grid cells) and a temporal resolution of between 1000 and 4000 years. Using our model, we mapped habitat stability over time using three approaches, comparing our modeled stability estimates to existing knowledge of Afrotropical refugia, as well as contemporary patterns of major keystone tropical food resources used by chimpanzees, figs (Moraceae), and palms (Arecacae). Results show habitat stability congruent with known glacial refugia across Africa, suggesting their extents may have been underestimated for chimpanzees, with potentially up to approximately 60,000 km(2) of previously unrecognized glacial refugia. The refugia we highlight coincide with higher species richness for figs and palms. Our results provide spatio-temporally explicit insights into the role of refugia across the chimpanzee range, forming the empirical foundation for developing and testing hypotheses about behavioral, ecological, and genetic diversity with additional data. This methodology can be applied to other species and geographic areas when sufficient data are available.

The western chimpanzee (Pan troglodytes verus), a subspecies of the common chimpanzee, is currently listed as Critically Endangered. Human-driven habitat loss and infectious diseases are causing dramatic chimpanzee population declines and range contractions that are bringing these primates to the brink of extinction. Little information is currently available on the occurrence of diarrhoea-causing enteric protist species in chimpanzees in general, and in western chimpanzees in particular, or on the role of humans as a potential source of these infections. In this prospective molecular epidemiological study, we investigated the presence, genetic variability, and zoonotic potential of enteric protists in faecal samples from western chimpanzees (n = 124) and humans (n = 9) in Comoé National Park, Côte d'Ivoire. Parasite detection and genotyping were conducted by using polymerase chain reaction (PCR) and Sanger sequencing. The protist species found in the chimpanzee samples were Entamoeba dispar (14.5%), Blastocystis sp. (11.3%), Giardia duodenalis (5.8%), Troglodytella abrassarti (2.5%) and Cryptosporidium hominis (0.8%). The protist species found in the human samples were G. duodenalis (22.2%) and Blastocystis sp. (11.1%). Entamoeba histolytica, Enterocytozoon bieneusi, and Balantioides coli were undetected in both chimpanzee and human samples. Sequence analyses revealed the presence of Blastocystis subtype (ST) 1 (alleles 4 and 8) and ST3 (allele 24) in chimpanzees, and ST3 (allele 52) in humans. ST1 allele 8 represents a chimpanzee-adapted Blastocystis genetic variant. Cross-species transmission of pathogenic enteric protists between chimpanzees and humans might be possible in Comoé National Park, although the frequency and extent of zoonotic events remain to be fully elucidated.

Funder: Max-Planck-Gesellschaft (Max Planck Society); doi: https://doi.org/10.13039/501100004189, Funder: Max Planck Society Innovation Fund Heinz L. Krekeler Foundation, Much like humans, chimpanzees occupy diverse habitats and exhibit extensive behavioural variability. However, chimpanzees are recognized as a discontinuous species, with four subspecies separated by historical geographic barriers. Nevertheless, their range-wide degree of genetic connectivity remains poorly resolved, mainly due to sampling limitations. By analyzing a geographically comprehensive sample set amplified at microsatellite markers that inform recent population history, we found that isolation by distance explains most of the range-wide genetic structure of chimpanzees. Furthermore, we did not identify spatial discontinuities corresponding with the recognized subspecies, suggesting that some of the subspecies-delineating geographic barriers were recently permeable to gene flow. Substantial range-wide genetic connectivity is consistent with the hypothesis that behavioural flexibility is a salient driver of chimpanzee responses to changing environmental conditions. Finally, our observation of strong local differentiation associated with recent anthropogenic pressures portends future loss of critical genetic diversity if habitat fragmentation and population isolation continue unabated.

Large brains and behavioural innovation are positively correlated, species-specific traits, associated with the behavioural flexibility animals need for adapting to seasonal and unpredictable habitats. Similar ecological challenges would have been important drivers throughout human evolution. However, studies examining the influence of environmental variability on within-species behavioural diversity are lacking despite the critical assumption that population diversification precedes genetic divergence and speciation. Here, using a dataset of 144 wild chimpanzee (Pan troglodytes) communities, we show that chimpanzees exhibit greater behavioural diversity in environments with more variability - in both recent and historical timescales. Notably, distance from Pleistocene forest refugia is associated with the presence of a larger number of behavioural traits, including both tool and non-tool use behaviours. Since more than half of the behaviours investigated are also likely to be cultural, we suggest that environmental variability was a critical evolutionary force promoting the behavioural, as well as cultural diversification of great apes.

Despite the large body of literature on ape conservation, much of the data needed for evidence‐based conservation decision‐making is still not readily accessible and standardized, rendering cross‐site comparison difficult. To support knowledge synthesis and to complement the IUCN SSC Ape Populations, Environments and Surveys database, we created the A.P.E.S. Wiki (https://apeswiki.eva.mpg.de), an open‐access platform providing site‐level information on ape conservation status and context. The aim of this Wiki is to provide information and data about geographical ape locations, to curate information on individuals and organizations active in ape research and conservation, and to act as a tool to support collaboration between conservation practitioners, scientists, and other stakeholders. To illustrate the process and benefits of knowledge synthesis, we used the momentum of the update of the conservation action plan for western chimpanzees (Pan troglodytes verus) and began with this critically endangered taxon. First, we gathered information on 59 sites in West Africa from scientific publications, reports, and online sources. Information was compiled in a standardized format and can thus be summarized using a web scraping approach. We then asked experts working at those sites to review and complement the information (20 sites have been reviewed to date). We demonstrate the utility of the information available through the Wiki, for example, for studying species distribution. Importantly, as an open‐access platform and based on the well‐known wiki layout, the A.P.E.S. Wiki can contribute to direct and interactive information sharing and promote the efforts invested by the ape research and conservation community. The Section on Great Apes and the Section on Small Apes of the IUCN SSC Primate Specialist Group will guide and support the expansion of the platform to all small and great ape taxa. Similar collaborative efforts can contribute to extending knowledge synthesis to all nonhuman primate species.

Funder: Max-Planck-Gesellschaft (Max Planck Society); doi: https://doi.org/10.13039/501100004189, Funder: Heinz L. Krekeler Foundation, Large brains and behavioural innovation are positively correlated, species-specific traits, associated with the behavioural flexibility animals need for adapting to seasonal and unpredictable habitats. Similar ecological challenges would have been important drivers throughout human evolution. However, studies examining the influence of environmental variability on within-species behavioural diversity are lacking despite the critical assumption that population diversification precedes genetic divergence and speciation. Here, using a dataset of 144 wild chimpanzee (Pan troglodytes) communities, we show that chimpanzees exhibit greater behavioural diversity in environments with more variability — in both recent and historical timescales. Notably, distance from Pleistocene forest refugia is associated with the presence of a larger number of behavioural traits, including both tool and non-tool use behaviours. Since more than half of the behaviours investigated are also likely to be cultural, we suggest that environmental variability was a critical evolutionary force promoting the behavioural, as well as cultural diversification of great apes.

AimPaleoclimate reconstructions have enhanced our understanding of how past climates may have shaped present-day biodiversity. We hypothesize that habitat stability in historical Afrotropical refugia played a major role in the habitat suitability and persistence of chimpanzees (Pan troglodytes) during the late Quaternary. We aimed to build a dynamic model of changing habitat suitability for chimpanzees at fine spatio-temporal scales to provide a new resource for understanding their ecology, behaviour and evolution.LocationAfrotropics.TaxonChimpanzee (Pan troglodytes), including all four subspecies (P. t. verus, P. t. ellioti, P. t. troglodytes, P. t. schweinfurthii).MethodsWe used downscaled bioclimatic variables representing monthly temperature and precipitation estimates, historical human population density data and an extensive database of georeferenced presence points to infer chimpanzee habitat suitability at 62 paleoclimatic time periods across the Afrotropics based on ensemble species distribution models. We mapped habitat stability over time using an approach that accounts for dispersal between time periods, and compared our modelled stability estimates to existing knowledge of Afrotropical refugia. Our models cover a spatial resolution of 0.0467 degrees (approximately 5.19 km2 grid cells) and a temporal resolution of every 1,000–4,000 years dating back to the Last Interglacial (120,000 BP).ResultsOur results show high habitat stability concordant with known historical forest refugia across Africa, but suggest that their extents are underestimated for chimpanzees. We provide the first fine-grained dynamic map of historical chimpanzee habitat suitability since the Last Interglacial which is suspected to have influenced a number of ecological-evolutionary processes, such as the emergence of complex patterns of behavioural and genetic diversity.Main ConclusionsWe provide a novel resource that can be used to reveal spatio-temporally explicit insights into the role of refugia in determining chimpanzee behavioural, ecological and genetic diversity. This methodology can be applied to other taxonomic groups and geographic areas where sufficient data are available.

Noninvasive samples as a source of DNA are gaining interest in genomic studies of endangered species. However, their complex nature and low endogenous DNA content hamper the recovery of good quality data. Target capture has become a productive method to enrich the endogenous fraction of noninvasive samples, such as faeces, but its sensitivity has not yet been extensively studied. Coping with faecal samples with an endogenous DNA content below 1% is a common problem when prior selection of samples from a large collection is not possible. However, samples classified as unfavourable for target capture sequencing might be the only representatives of unique specific geographical locations, or to answer the question of interest. To explore how library complexity may be increased without repeating DNA extractions and generating new libraries, in this study we captured the exome of 60 chimpanzees (Pan troglodytes) using faecal samples with very low proportions of endogenous content (, C.F. is supported by the “La Caixa” doctoral fellowship program. M.A.E. is supported by an FPI (Formación de Personal Investigador) PRE2018-083966 from Ministerio de Ciencia, Universidades e Investigación. The Pan African Programme: The Cultured Chimpanzee (PanAf) is generously funded by the Max Planck Society, the Max Planck Society Innovation Fund and the Heinz L. Krekeler Foundation. E.L is supported by CGL2017-82654-P (MINECO/FEDER,UE). M.K. is supported by “la Caixa” Foundation (ID 100010434), fellowship code LCF/BQ/PR19/11700002. T.M.-B is supported by funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No. 864203), BFU2017-86471-P (MINECO/FEDER, UE), “Unidad de Excelencia María de Maeztu”, funded by the AEI (CEX2018-000792-M), Howard Hughes International Early Career, Obra Social "La Caixa" and Secretaria d’Universitats i Recerca and CERCA Programme del Departament d’Economia i Coneixement de la Generalitat de Catalunya (GRC 2017 SGR 880).

The black-bellied pangolin (Phataginus tetradactyla) is the most arboreal pangolin species, and occurs in West and Central Africa. The species is small, weighing up to 3.6 kg, and has a total length of up to 120 cm. Up to two-thirds of the total length comprises the extremely long tail. The species is more diurnal than other pangolins and may have a preference for riverine and swamp forests. Breeding throughout the year, the black-bellied pangolin gives birth in tree hollows to a single offspring, likely annually. Unlike other pangolins, the species mainly predates on ants and does not appear to prey on termites. Predominantly solitary, the only lasting social bonds appear to occur between a mother and offspring during maternal care. The black-bellied pangolin is threatened by overexploitation, including hunting and poaching for the bushmeat and traditional medicine trades and illegal international trade to Asia, and habitat loss and degradation.

Primates often consume either bark or cambium (inner bark) as a fallback food to complete their diet during periods of food scarcity. Wild chimpanzees exhibit great behavioral diversity across Africa, as studies of new populations frequently reveal. Since 2014, we have been using a combination of camera traps and indirect signs to study the ecology and behavior of wild chimpanzees (Pan troglodytes verus) in Comoé National Park, Ivory Coast, to document and understand the behavioral adaptations that help them to survive in a savanna–forest mosaic landscape. We found that Comoé chimpanzees peel the bark of the buttresses of kapok tree (Ceiba pentandra) trees to eat the cambium underneath. Individuals of all sex/age classes across at least six neighboring communities peeled the bark, but only during the late rainy season and beginning of the dry season, when cambium may represent an important fallback food. Baboons (Papio anubis) also target the same trees but mainly eat the bark itself. Most of the bark-peeling wounds on Ceiba trees healed completely within 2 years, seemingly without any permanent damage. We recorded chimpanzees visiting trees in early stages of wound recovery but leaving them unpeeled. Only 6% of peeled trees (N = 53) were reexploited after a year, suggesting that chimpanzees waited for the rest of the trees to regrow the bark fully before peeling them again, thus using them sustainably. Many human groups of hunter-gatherers and herders exploited cambium sustainably in the past. The observation that similar sustainable bark-peeling behavior evolved in both chimpanzees and humans suggests that it has an important adaptive value in harsh environments when other food sources become seasonally scarce, by avoiding the depletion of the resource and keeping it available for periods of scarcity.

Anthrax is a globally important animal disease and zoonosis. Despite this, our current knowledge of anthrax ecology is largely limited to arid ecosystems, where outbreaks are most commonly reported. Here we show that the dynamics of an anthrax-causing agent, Bacillus cereus biovar anthracis, in a tropical rainforest have severe consequences for local wildlife communities. Using data and samples collected over three decades, we show that rainforest anthrax is a persistent and widespread cause of death for a broad range of mammalian hosts. We predict that this pathogen will accelerate the decline and possibly result in the extirpation of local chimpanzee (Pan troglodytes verus) populations. We present the epidemiology of a cryptic pathogen and show that its presence has important implications for conservation.

The goal of this study was to explain the patterns of diversity and distribution of arboreal social bees nesting in forest habitats of the Comoé National park, within the home-ranges of wild chimpanzees that consume their honey. Investigations were done using a total sixteen plots, one hectare each, established in three habitat types (mature forest island, secondary forest island and gallery forest). The diversity and distribution of arboreal social bees was estimated with visuals searches. The exploitation of the beehives of these bee by the chimpanzees was also evaluated using chimpanzees’ honey dipping tools as indicators. Results revealed five bees’ species belonging to two tribes; Meliponini (Meliponula ferruginea, Meliponula togoensis, Meliponula bocandei, Hypotrigona gribodoi) and Apini (Apis mellifera). Frequent exploitation of the honey of stingless bees by the chimpanzees was observed, except for H. gribodoi. Meliponula ferruginea was the most exploited species by chimpanzees. A total of 114 beehives were found in the overall established plots leading to an estimated density of 2.4 beehives/ha in the study area. Among the surveyed habitats, mature forest island was found to harbor the highest beehive density (4.2 beehives/ha), followed respectively by secondary-forest island (1.9 beehives/ha) and gallery forest (1.1 beehives/ha). Finally, all bee species were found nesting in cavities of trees with a DBH ranging from 15 to 87.3 cm, with a special preference for Dialium guinneense. However, the DBH of nesting trees and beehives’ height, measured from the ground level, did not significantly influence the honey exploitation by chimpanzees. In sum bee species diversity and distribution might be important in the survival of chimpanzees of a forest savanna landscape.

Funding: Generous funding for the Pan African Programme was provided by the Max Planck Society, Max Planck Society Innovation Fund, Krekeler Foundation, Robert Bosch Foundation, Chimbo Foundation and UCSD-SALK Institute Center for Academic Research and Training in Anthropogeny (CARTA). Chimpanzees possess a large number of behavioral and cultural traits among non-human species. The ‘disturbance hypothesis’ predicts that human impact depletes resources and disrupts social learning processes necessary for behavioral and cultural transmission. We used an unprecedented data set of 144 chimpanzee communities, with information on 31 behaviors, to show that chimpanzees inhabiting areas with high human impact have a mean probability of occurrence reduced by 88%, across all behaviors, compared to low impact areas. This behavioral diversity loss was evident irrespective of the grouping or categorization of behaviors. Therefore, human impact may not only be associated with the loss of populations and genetic diversity, but also affects how animals behave. Our results support the view that ‘culturally significant units’ should be integrated into wildlife conservation. Postprint

Objectives – We investigated occurrences and patterns of terrestrial nocturnal activity in wild chimpanzees (Pan troglodytes) and modelled the influence of various ecological predictors on nocturnal activity. Methods – Data were extracted from terrestrial camera-trap footage and ecological surveys from 22 chimpanzee study sites participating in the Pan African Programme: The Cultured Chimpanzee. We described videos demonstrating nocturnal activity, and we tested the effects of the percentage of forest, abundance of predators (lions, leopards and hyenas), abundance of large mammals (buffalos and elephants), average daily temperature, rainfall, human activity, and percent illumination on the probability of nocturnal activity. Results – We found terrestrial nocturnal activity to occur at 18 of the 22 study sites, at an overall average proportion of 1.80% of total chimpanzee activity, and to occur during all hours of the night, but more frequently during twilight hours. We found a higher probability of nocturnal activity with lower levels of human activity, higher average daily temperature, and at sites with a larger percentage of forest. We found no effect of the abundance of predators and large mammals, rainfall, or moon illumination. Discussion – Chimpanzee terrestrial nocturnal activity appears widespread yet infrequent, which suggests a consolidated sleeping pattern. Nocturnal activity may be driven by the stress of high daily temperatures and may be enabled at low levels of human activity. Human activity may exert a relatively greater influence on chimpanzee nocturnal behavior than predator presence. We suggest that chimpanzee nocturnal activity is flexible, enabling them to respond to changing environmental factors.

Over a 6 month period during the dry season, from the end of October 2014 to the beginning of May 2015, we studied tool use behavior of previously unstudied and non‐habituated savanna chimpanzees (Pan troglodytes verus) living in the Comoé National Park, Ivory Coast (CI). We analyzed all the stick tools and leaf‐sponges found that the chimpanzees used to forage for ants, termites, honey, and water. We found a particular behavior to be widespread across different chimpanzee communities in the park, namely, dipping for water from tree holes using sticks with especially long brush‐tip modifications, using camera traps, we recorded adults, juveniles, and infants of three communities displaying this behavior. We compared water dipping and honey dipping tools used by Comoé chimpanzees and found significant differences in the total length, diameter, and brush length of the different types of fluid‐dipping tools used. We found that water dipping tools had consistently longer and thicker brush‐tips than honey dipping tools. Although this behavior was observed only during the late dry season, the chimpanzees always had alternative water sources available, like pools and rivers, in which they drank without the use of a tool. It remains unclear whether the use of a tool increases efficient access to water. This is the first time that water dipping behavior with sticks has been found as a widespread and well‐established behavior across different age and sex classes and communities, suggesting the possibility of cultural transmission. It is crucial that we conserve this population of chimpanzees, not only because they may represent the second largest population in the country, but also because of their unique behavioral repertoire., Chimpanzees in Comoé National Park use specialized stick tools to collect water from tree holes (WDTs). WDTs are significantly different from tools used to gather honey. The use of WDTs is widespread across neighboring communities in the park.

Carrion scavenging is a well‐studied phenomenon, but virtually nothing is known about scavenging on plant material, especially on remnants of cracked nuts. Just like meat, the insides of hard‐shelled nuts are high in energetic value, and both foods are difficult to acquire. In the Taï forest, chimpanzees (Pan troglodytes) and red river hogs (Potamochoerus porcus) crack nuts by using tools or strong jaws, respectively. In this study, previously collected non‐invasive camera trap data were used to investigate scavenging by sooty mangabeys (Cercocebus atys), two species of Guinea fowl (Agelestres meleagrides; Guttera verreauxi), and squirrels (Scrunidae spp.) on the nut remnants cracked by chimpanzees and red river hogs. We investigated how scavengers located nut remnants, by analyzing their visiting behavior in relation to known nut‐cracking events. Furthermore, since mangabeys are infrequently preyed upon by chimpanzees, we investigated whether they perceive an increase in predation risk when approaching nut remnants. In total, 190 nut‐cracking events were observed in four different areas of Taï National Park, Ivory Coast. We could confirm that mangabeys scavenged on the nuts cracked by chimpanzees and hogs and that this enabled them to access food source that would not be accessible otherwise. We furthermore found that mangabeys, but not the other species, were more likely to visit nut‐cracking sites after nut‐cracking activities than before, and discuss the potential strategies that the monkeys could have used to locate nut remnants. In addition, mangabeys showed elevated levels of vigilance at the chimpanzee nut‐cracking sites compared with other foraging sites, suggesting that they perceived elevated danger at these sites. Scavenging on remnants of cracked nuts is a hitherto understudied type of foraging behavior that could be widespread in nature and increases the complexity of community ecology in tropical rainforests., By use of camera trap videos it was confirmed that mangabeys scavenge on the nut remnants cracked by chimpanzees and red river hogs. Squirrels and two types of guinea fowl might scavenge on these nut remnants but this could not be seen clearly. Looking at the visitation rate before and after nut cracking events it was found that the possible scavenging species were more present at the nut cracking sites after a nut cracking event took place. It was found that mangabeys have an increase in vigilance behavior at chimpanzee nut cracking sites compared with outside these chimpanzee nut cracking sites, indicating that the mangabeys perceive a higher risk at these nut cracking sites.

The authors would like to thank the Max Planck Society and Krekeler Foundation for generous funding of the Pan African Programme. The study of the archaeological remains of fossil hominins must rely on reconstructions to elucidate the behaviour that may have resulted in particular stone tools and their accumulation. Comparatively, stone tool use among living primates has illuminated behaviours that are also amenable to archaeological examination, permitting direct observations of the behaviour leading to artefacts and their assemblages to be incorporated. Here, we describe newly discovered stone tool-use behaviour and stone accumulation sites in wild chimpanzees reminiscent of human cairns. In addition to data from 17 mid- to long-term chimpanzee research sites, we sampled a further 34 Pan troglodytes communities. We found four populations in West Africa where chimpanzees habitually bang and throw rocks against trees, or toss them into tree cavities, resulting in conspicuous stone accumulations at these sites. This represents the first record of repeated observations of individual chimpanzees exhibiting stone tool use for a purpose other than extractive foraging at what appear to be targeted trees. The ritualized behavioural display and collection of artefacts at particular locations observed in chimpanzee accumulative stone throwing may have implications for the inferences that can be drawn from archaeological stone assemblages and the origins of ritual sites. Publisher PDF