Marie-Claude Huynen

Frugivory and Seed Dispersal by Northern Pigtailed Macaques (Macaca leonina), in Thailand

Tropical rain forest conservation requires a good understanding of plant–animal interactions. Seed dispersal provides a means for plant seeds to escape competition and density-dependent seed predators and pathogens and to colonize new habitats. This makes the role and effectiveness of frugivorous species in the seed dispersal process an important topic. Northern pigtailed macaques (Macaca leonina) may be effective seed dispersers because they have a diverse diet and process seeds in several ways (swallowing, spitting out, or dropping them). To investigate the seed dispersal effectiveness of a habituated group of pigtailed macaques in Khao Yai National Park, Thailand, we examined seed dispersal quantity (number of fruit species eaten, proportion in the diet, number of feces containing seeds, and number of seeds processed) and quality (processing methods used, seed viability and germination success, habitat type and distance from parent tree for the deposited seeds, and dispersal patterns) via focal and scan sampling, seed collection, and germination tests. We found thousands of seeds per feces, including seeds up to 58xa0mm in length and from 88 fruit species. Importantly, the macaques dispersed seeds from primary to secondary forests, via swallowing, spitting, and dropping. Of 21 species, the effect of swallowing and spitting was positive for two species (i.e., processed seeds had a higher % germination and % viability than control seeds), neutral for 13 species (no difference in % germination or viability), and negative (processed seeds had lower % germination and viability) for five species. For the final species, the effect was neutral for spat-out seeds but negative for swallowed seeds. We conclude that macaques are effective seed dispersers in both quantitative and qualitative terms and that they are of potential importance for tropical rain forest regeneration.

Group size of a permanent large group of agile mangabeys (Cercocebus agilis) at Bai Hokou, Central African Republic.

White-eyelid mangabeys (genus Cercocebus) live in groups of highly variable size. Because of their semi-terrestrial behaviour and preference for dense forest habitats, re-liable data on group size are scarce. During a 5-month study, we collected 17 group counts on a habituated group of agile mangabeys (C. agilis) at Bai Hokou in the Central African Republic. We found a stable group size of approximately 135 individuals. This permanent large grouping pattern is known to occur among several populations of white-eyelid mangabeys and is congruent with extreme group sizes reported in mandrills at Lopé in Gabon.

Optimizing scale search in species distribution models

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 nextinction 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.