Thurston C. Hicks

Devastating Decline of Forest Elephants in Central Africa

African forest elephants– taxonomically and functionally unique–are being poached at accelerating rates, but we lack range-wide information on the repercussions. Analysis of the largest survey dataset ever assembled for forest elephants (80 foot-surveys; covering 13,000 km; 91,600 person-days of fieldwork) revealed that population size declined by ca. 62% between 2002–2011, and the taxon lost 30% of its geographical range. The population is now less than 10% of its potential size, occupying less than 25% of its potential range. High human population density, hunting intensity, absence of law enforcement, poor governance, and proximity to expanding infrastructure are the strongest predictors of decline. To save the remaining African forest elephants, illegal poaching for ivory and encroachment into core elephant habitat must be stopped. In addition, the international demand for ivory, which fuels illegal trade, must be dramatically reduced.

Chimpanzee accumulative stone throwing

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.

Protected Areas in Tropical Africa: Assessing Threats and Conservation Activities

Numerous protected areas (PAs) have been created in Africa to safeguard wildlife and other natural resources. However, significant threats from anthropogenic activities and decline of wildlife populations persist, while conservation efforts in most PAs are still minimal. We assessed the impact level of the most common threats to wildlife within PAs in tropical Africa and the relationship of conservation activities with threat impact level. We collated data on 98 PAs with tropical forest cover from 15 countries across West, Central and East Africa. For this, we assembled information about local threats as well as conservation activities from published and unpublished literature, and questionnaires sent to long-term field workers. We constructed general linear models to test the significance of specific conservation activities in relation to the threat impact level. Subsistence and commercial hunting were identified as the most common direct threats to wildlife and found to be most prevalent in West and Central Africa. Agriculture and logging represented the most common indirect threats, and were most prevalent in West Africa. We found that the long-term presence of conservation activities (such as law enforcement, research and tourism) was associated with lower threat impact levels. Our results highlight deficiencies in the management effectiveness of several PAs across tropical Africa, and conclude that PA management should invest more into conservation activities with long-term duration.

Impact of Humans on Long-Distance Communication Behaviour of Eastern Chimpanzees (Pan troglodytes schweinfurthii) in the Northern Democratic Republic of the Congo

We systematically recorded all long-distance chimpanzee vocalizations and tree drums over a 26-month study period in 13 forest regions in the Democratic Republic of the Congo. We found that the frequency of chimpanzee vocalizations and tree drums was considerably higher in the remote Gangu Forest than in other forest regions closer to human settlements and roads. We present evidence indicating that chimpanzees may reduce their levels of vocalizations in areas characterized by high levels of human hunting. The chimpanzees appear to have the behavioural flexibility necessary to modify their behaviour in areas where humans are a major threat. We discuss the possible consequences of this reduction in vocalization rate on the social system of the chimpanzees.

Reactions of Bili‐Uele Chimpanzees to Humans in Relation to Their Distance From Roads and Villages

In order to assess the impact of human activities on chimpanzee behavior, we compared reactions to humans of Eastern chimpanzees (Pan troglodytes schweinfurthii) living in proximity to and at a distance from roads and settlements in the Bili‐Uele landscape in Northern Democratic Republic of the Congo (DRC). We found that chimpanzees in the remote Gangu Forest were more likely to show curious or neutral reactions to us and were less likely to flee than those living closer to roads. In addition, arboreal contact durations with Gangu chimpanzees lasted significantly longer than elsewhere. The most likely explanation for this phenomenon is that with increasing distance from roads, chimpanzees have in the recent past had fewer negative encounters with humans, and thus never learned to fear them. The discovery of this population of “naïve chimpanzees” presents us with an important research and conservation opportunity that may result in the installation of a long‐term research site and increased protection of the population. Am. J. Primatol. 74:721‐733, 2012.

Fluid dipping technology of chimpanzees in Comoé National Park, Ivory Coast

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.

Chimpanzee tool use in northern DR Congo is not tied to abundance of insect prey

Classic ecological models of social groups suggest that increasing group size typically leads to a decrease in both individual predation risk and net food intake, with optimal group size being a compromise between these benefits and costs. Among rainforest primates, the main antipreda-tor benefits of sociality are thought to result from the dilution effect and collective detection of predators. However, recent research suggests that vegetation density in rainforest habitats limits the benefits of collective detection against ambush predators such as raptors, felids and snakes. Further, while larger groups are acknowledged to be more conspicuous to predators, it is widely assumed that this cost is unlikely to outweigh dilution benefits. Here we show in a simple model that per-individual rates of both encounters with predators and successful ambush attacks per encounter can increase with group size, under conditions likely to hold for many primate groups (when increases in group size lead to increases in group spread, conspicuousness and daily trav-el distance). Consequently, individual risk against ambush predators that employ a sit-and-wait strategy to search for prey, such as many snakes and some raptors, is lowest in small to medium-sized groups. In contrast, individuals in relatively large groups are favoured against ambush pred-ators like felids that employ a cruising strategy to search for prey, although even in this case in-creasing group size above some threshold increases individual risk. These results suggest that maximum group size among primates can be limited by increasing predation risk. Research fo-cused on primate predators is needed to determine the extent to which the model accurately re-flects their behaviour.Bushmeat hunting contributes to the decline of primate species across Africa; however, few studies have explored how such practises change over time in specific localities and how changes in land-use patterns and economic drivers may enhance threats to primates in Muslim dominated areas where, traditionally, primates are spared from such trade. The Haut Niger National Park (HNNP) is one of only two national parks in the Republic of Guinea. The park is one of the last remaining important formations of dry forest-savannah mosaics in West Africa and is a site of high conservation priority for ungulates and the western subspecies of chimpanzee. This study aimed to: (1) estimate the diversity and abundance of animal species sold for consumption across several markets in and around the HNNP, (2) analyse the evolution of the bushmeat trade since the mid-1990s, and (3) identify the players and drivers of the commercial bushmeat trade in the area. Local market assessments were conducted across four village markets and in Faranah, one of the closest urban areas abutting the HNNP. We successfully identified 5,807 wildlife carcasses of 46 species and 22 families on markets surveyed over a 7 month period spanning both the dry and wet seasons. In addition, semi-structured interviews with hunters, farmers and people involved in the bushmeat trade helped identify more recent drivers of the bushmeat trade in the HNNP. Our results indicated an increase in diversity of species targeted and the influence of crop-foraging and local microcredit systems in exacerbating the presence of primate species sold at bushmeat stalls in urban areas. Finally, whilst identifying key recommendations and gaps for future research, this study emphasises the growing risks facing primates as targets for bushmeat where people depend on agriculture and natural resource extraction for subsistence. This study complied with the International Primatological Society (IPS) Guidelines for the Use of Nonhuman Primates in Research.Comparative studies of primate grasping and manipulative behaviours in captivity have highlighted, among others, two human abilities that are generally considered unique compared with other primates: (1) the use of forceful precision and power squeeze grips involving the use of the thumb, and (2) a species-wide dominant use of one hand (usually the right hand), known as laterality. However, recent research has highlighted a diversity of precision and power grips in general among many non-human primates, and there is much debate around the potential for population-level or species-wide laterality in non-human primates. The majority of this research to date has been done on captive primates performing specific manipulative tasks, which may bias or confound these species comparisons. Comparatively little research has been done on hand use in wild primates, especially during natural, non-manipulative activities, including locomotion. Here, we investigate hand use during locomotor and non-locomotor behaviours in wild mountain gorillas ( Gorilla beringei beringei , Bwindi Impenetrable National Park, Uganda), wild chimpanzees ( Pan troglodytes verus , Tai National Park, Cote d’Ivoire) and chimpanzees kept under semi-natural conditions ( Pan troglodytes ssp., Chimfunshi Wildlife Trust, Zambia). Preliminary results propose that hand grips are similar between gorillas and chimpanzees during the manipulation of common object types. Bwindi gorillas show various hand use strategies during the processing of several plant foods. Chimfunshi chimpanzees also use forceful precision grips during daily manipulative tasks, suggesting that this is not a uniquely human ability.

5th Congress of the European Federation for Primatology. Antwerp, Belgium, September 10-13, 2013

DOI: 10.1159/000354129 298 5th Congress of the European Federation for Primatology researchers usually argue that one of the distinguishing features of non-human primates’ gestures is their high degree of flexibility, which can be considered in different ways: (1) ‘means-end dissociation’, which refers to the use of a particular gesture in different functional contexts and/or several gestures for one specific context, and (2) gesture sequences which consist of combinations of two or more gestural signals. Both strategies enable non-human primates to adjust their gesture use to their partner’s behaviour and to increase the range of potential meanings that can be conveyed by combining the components of a more or less limited gestural repertoire. Because of their flexible use, however, very few gestures have a specific meaning, but their meaning is defined by the context in which they occur. Thus, in contrast to many vocalizations of non-human primates, their gestures are (1) less context-specific and do not represent functionally referential signals and, related to this, (2) gesture sequences do not represent meaningful combinations used for other functions than their single components. Therefore, I will first provide an overview of recent research on the flexible use of gestures in great apes to demonstrate how they create meaning in their interactions with others. I will then discuss how these findings relate to evidence from vocal studies with the aim to identify ‘blind spots’ and biases that currently constrain a fruitful debate about the origins of human language.Comparative studies of primate grasping and manipulative behaviours in captivity are numerous but there has been little research on hand use in the wild. Hand use during wild non-locomotor behaviours may reveal increased ranges of joint mobility or manipulative behaviours that have been previously ignored or underestimated. Manipulative behaviours in apes can strongly correlate with different habitats at the species and population level. Chimpanzees more often use tools in the wild and thus are thought to be more manipulative than gorillas. However, captive studies have demonstrated high dexterity in both taxa. We investigate hand use during manipulation (e.g. food processing, tool-use) in wild mountain gorillas (Gorilla beringei, Bwindi Impenetrable National Park, Uganda) and wild chimpanzees (Pan troglodytes verus, Tai National Park, Cote d’Ivoire). We used video data collected in the wild that included 32 gorilla (n=9 individuals) and 53 chimpanzee (n=11 individuals) instances of manipulative tasks. Digital images were extracted and analysed frame by frame. Preliminary results show that hand grips are similar between gorillas and chimpanzees during the manipulation of common food objects, such as long plant stems or branches. During the manipulation of species-specific food objects, gorillas use variable thumb-index grips during the manipulation of thistles and small plant stems, while chimpanzees use similar grips during nut-cracking. These preliminary results suggest that Bwindi mountain gorillas have similarly high dexterity as that of Tai chimpanzees despite not being tool-users. Gorillas frequently use precision grasping more to obtain small rather than large food items, which is similar to chimpanzees and other non-human primates.Previous studies have shown a positive relationship between proximity to humans or habitat fragmentation and parasitic levels in non-human primates (NHPs). However, to date few have explicitly explored links between parasite load and stress conditions. To better understand the links between parasite prevalence and NHP immune system efficiency and stress levels, faecal samples of Alouatta palliata and the critically endangered Ateles geoffroyi geoffroyi were non-invasively collected in northern Costa Rica. We investigated whether the presence of gastrointestinal parasites was related to the abundance of hormones (cortisol and testosterone). Samples were gathered across three areas differing in the frequency and diversity of human presence, i.e. around the Cano Palma Biological Station, near villages and at ecotourism sites. Two grams of each faecal sample were stored in a sugar saturated solution with 10% formalin to conserve the parasites; the remaining matter was dried to preserve DNA and steroid hormones. The samples enabled the quantification of parasites as well as testosterone and cortisol levels using ELISA as proxies of general health status and stress levels. Data on parasite abundance and hormone levels were contrasted across the two species and the three different sampling areas. Furthermore, we assessed the genetic exchange among the different groups of primates sampled. We genetically analysed the samples using 12 microsatellites previously validated by the University of Costa Rica. We verified whether transmission of parasites among the groups could be possible concomitant to the genetic exchange. This study aimed to better understand and assess the impact of human factors on NHP health and across NHPs with different socio-ecological characteristics.DOI: 10.1159/000354129 290 5th Congress of the European Federation for Primatology considerably between species for any given body size. Numerous hypotheses have been put forward to explain this variation. In recent years, we have tested predictions that flow from a framework focusing on the energetic aspects of having a large amount of the metabolically expensive brain tissue. In this talk, I will give an overview of our findings from broad comparative phylogenetic studies in mammals, and their implications for our understanding of non-human and human primate evolution. In sum, we found evidence for two pathways to increase relative brain size compared to the ancestral state. First, a species may change its lifestyle to allow for a stable increase in its total energy budget, e.g. by changing its diet. Alternatively, or in combination with the first pathway, a species may allocate more energy to the brain and less to other expensive functions such as offspring production. Ultimately, this option results in very low population growth rates even in good conditions, as found in great apes. A further increase in brain size would not be compatible with demographically viable populations in these large-brained primates. However, using comparative evidence from mammals, we demonstrate that help from non-mothers can alleviate this trade-off between reproductive effort and brain size. Nevertheless, the energetic constraints on brain size evolution will only be overcome in species that can actually benefit from enhanced cognitive abilities. While such benefits are potentially ubiquitous, we would expect them to be undermined by unavoidable mortality in some socioecological conditions, and by the difficulty of transferring knowledge across generations in some social systems. A combined test of all these considerations remains a challenge, largely due to the shortcomings of the distinct datasets, but I will present the newest data and results from our current projects.Throughout their range across Africa, chimpanzees (Pan troglodytes) are threatened with extinction due to habitat destruction, disease and unsustainable levels of hunting and capture, in spite of being protected by national and international laws. In recent years, the bush meat and the pet trade have resulted in a significant increase in the number confiscated orphan chimpanzees. The Chimpanzee Conservation Centre (CCC), located in the High Niger National Park (HNNP), is the only Pan African Sanctuary Alliance (PASA)-accredited sanctuary caring for chimpanzee orphans in Guinea, West Africa. This sanctuary has been rehabilitating confiscated chimpanzees since 1997. With the aim of reinforcing the wild chimpanzee population of the HNNP and to enhance park protection, the CCC, in 2008, released a first group of 12 chimpanzees into the Mafou core area of the park. Five of those individuals have since settled at the release site and continue to be monitored. In August 2011, the CCC was able to re-enforce this resident group with the successful addition of 2 adult females. Post-release monitoring of these individuals involved distance monitoring using simple VHF and/or ARGOS and GPS store-on-board radio collars. Here, we present data downloaded in 2011–2012 from the GPS store-on-board collars of 2 adult males and these 2 additional adult females. These data allowed us to analyse their social dynamics, party composition, habitat preferences, day range and home range use. Our results indicate that these females integrated successfully into the resident group and that the behaviour of these wild-born released orphan chimpanzees mirrors that of wild counterparts inhabiting similar savannah dominated landscapes, suggesting that they have adapted appropriately to their release conditions.