Nest grouping patterns of bonobos (Pan paniscus) in relation to fruit availability in a forest-savannah mosaic

A topic of major interest in socio-ecology is the comparison of chimpanzees and bonobos’ grouping patterns. Numerous studies have highlighted the impact of social and environmental factors on the different evolution in group cohesion seen in these sister species. We are still lacking, however, key information about bonobo social traits across their habitat range, in order to make accurate inter-species comparisons. In this study we investigated bonobo social cohesiveness at nesting sites depending on fruit availability in the forest-savannah mosaic of western Democratic Republic of Congo (DRC), a bonobo habitat which has received little attention from researchers and is characterized by high food resource variation within years. We collected data on two bonobo communities. Nest counts at nesting sites were used as a proxy for night grouping patterns and were analysed with regard to fruit availability. We also modelled bonobo population density at the site in order to investigate yearly variation. We found that one community density varied across the three years of surveys, suggesting that this bonobo community has significant variability in use of its home range. This finding highlights the importance of forest connectivity, a likely prerequisite for the ability of bonobos to adapt their ranging patterns to fruit availability changes. We found no influence of overall fruit availability on bonobo cohesiveness. Only fruit availability at the nesting sites showed a positive influence, indicating that bonobos favour food ‘hot spots’ as sleeping sites. Our findings have confirmed the results obtained from previous studies carried out in the dense tropical forests of DRC. Nevertheless, in order to clarify the impact of environmental variability on bonobo social cohesiveness, we will need to make direct observations of the apes in the forest-savannah mosaic as well as make comparisons across the entirety of the bonobos’ range using systematic methodology

Predicting range shifts of African apes under global change scenarios

Aim: Modelling African great ape distribution has until now focused on current or past conditions, while future scenarios remain scarcely explored. Using an ensemble forecasting approach, we predicted changes in taxon-specific distribution under future scenarios of climate, land use and human populations for (1) areas outside protected areas (PAs) only (assuming complete management effectiveness of PAs), (2) the entire study region and (3) interspecies range overlap. Location: Tropical Africa. Methods: We compiled occurrence data (n = 5,203) on African apes from the IUCN A.P.E.S. database and extracted relevant climate-, habitat- and human-related predictors representing current and future (2050) conditions to predict taxon-specific range change under a best- and a worst-case scenario, using ensemble forecasting. Results: The predictive performance of the models varied across taxa. Synergistic interactions between predictors are shaping African ape distribution, particularly human-related variables. On average across taxa, a range decline of 50% is expected outside PAs under the best scenario if no dispersal occurs (61% in worst scenario). Otherwise, an 85% range reduction is predicted to occur across study regions (94% worst). However, range gains are predicted outside PAs if dispersal occurs (52% best, 21% worst), with a slight increase in gains expected across study regions (66% best, 24% worst). Moreover, more than half of range losses and gains are predicted to occur outside PAs where interspecific ranges overlap. Main Conclusions: Massive range decline is expected by 2050, but range gain is uncertain as African apes will not be able to occupy these new areas immediately due to their limited dispersal capacity, migration lag and ecological constraints. Given that most future range changes are predicted outside PAs, Africa\u27s current PA network is likely to be insufficient for preserving suitable habitats and maintaining connected ape populations. Thus, conservation planners urgently need to integrate land use planning and climate change mitigation measures at all decision-making levels both in range countries and abroad

Eco-éthologie des bonobos, Pan paniscus, dans l'ouest de la République Démocratique du Congo : pourquoi ces données sont importantes pour les programmes de conservation à long terme?

Endemic to the Democratic Republic of Congo (DRC) and classified as Endangered by IUCN, the Bonobo survival depends exclusively on management measures taken by a country having to deal concomitantly with several problems affecting its development. The current government’s intention to designate new protected areas need to be complemented by effective long-term conservation programs, taking into account both bonobos populations requirements and local socio-economic realities. As part of a WWF conservation program, our study focuses on recently discovered Bonobo populations in West RDC, an eccentric location of the species range. The region is characterized by numerous anthropogenic activities including logging and cattle ranching and is composed of forest-savannah mosaics in which Bonobo has hardly ever been studied in comparison with those evolving in central DRC rainforests. Preliminary observations already indicate that these Western populations differ from other known populations in terms of habitat use, with regular savannahs patches crossing and savannah fruits consumption. To shed further lights on species adaptation’s spectrum, our study investigates local population density; nesting sites choice; and diet composition. Here we present a baseline population density derived from 5 walks along transects using marked-nest count method and we discuss factors inducing nesting sites choice. Ultimately, our results should allow for the formulation of specific management recommendations to be used in regional conservation program

Bonobos, Pan paniscus, in the forest-savannah mosaics of West DR Congo: does spatial structure influence the forest use dynamics?

Bonobos, Pan paniscus, are endemic to the Democratic Republic of Congo (DRC) but the species’ range is still not precisely known. For example, the populations from West DRC have only been identified in 2005, following inventories conducted by WWF. This region is characterized by a forest-savannah mosaic, a particular ecotone with naturally fragmented forests, in which bonobos have hardly ever been studied in comparison with those evolving in central DRC rainforests. The area also increasingly includes numerous anthropogenic activities including logging and cattle ranching. Effective long-term conservation programs are then essential for the survival of bonobos’ populations. We decided to focus our study on bonobos’ forest use dynamics, testing spatial structure influence on bonobos’ density and forest use. This hypothesis is based on a landscape ecology theory, the pattern-process paradigm, establishing a triangular link between the structure, the composition and the ecological processes of a landscape. We used the interior-to-edge ratio to classify our study area (200km² of forests) in 5 categories of forest patches: (i) corridors (0.1 to 5.5km², ratio of 0), (ii) small patches (3.4 to 4.3km², ratios between 0.23 and 0.33), (iii) middle patch with edge area predominant (13.8km², ratio of 0.7), (iv) middle patch with interior area predominant (22.3km², ratio of 1.17), (v) big patch (122.2km², ratio of 1.43). We walked transects (total effort: 126km) to identify habitats (landscape composition) and bonobos’ use indices (nests and food remains – landscape ecological process). Results unexpectedly showed that bonobos use all forest patches, even corridors, mostly used for feeding. Small patches even include higher nest density than the big patch. Moreover, habitats with predominant Marantaceae understory are correlated with higher nest density. The study is still in process and sampling areas will be increased in further field work. The first results however already indicate that we could elaborate a model predicting bonobos’ presence according to habitats and spatial structure and designate forest patches to protect as a priority. This information should allow formulating specific management recommendations for regional conservation programs and logging concession

Eco-Ethology of bonobos, Pan paniscus, in West Democratic Republic of Congo; why are critical data so important for long-term conservation programs?

The Bonobo could be one of the species facing the biggest conservation challenge in the years to come. Endemic to the West Democratic Republic of Congo (DRC), its survival depends exclusively on the management measures taken by a country having to deal concomitantly with many problems affecting its development, i.e. demographic explosion, poverty, insecurity and deforestation. But the survival of bonobos, classified as Endangered by IUCN (2010) and restricted to a relatively small range, will require newly designated and effective protected areas. This will imply long-term conservation programs, taking into account the bonobos’ populations requirements, as well as the local socio-economic needs and realities. In 2005, a large population of bonobos has been identified in Western DRC, in a rather eccentric part of the species range compare with the best known populations inhabiting the rainforest of center DRC. The Western region, known as the Lake Tumba Landscape, is characterized by a relatively poor rural human population, an active bushmeat trade, and is divided into several logging concessions and cattle ranches. In 2007, WWF initiated a vast conservation program in the area, including an eco-tourism project involving the habituation of 2 bonobos populations. Until now, only sparse information has been gathered but preliminary studies indicate that habitat use by bonobos – a forest-savannah mosaic – differs substantially from that of other known populations. The objective of the research is to define the eco-ethological profile of those 2 populations. For this purpose, we will characterize diet and food preferences, examine population density and try to identify factors inducing nesting sites’ choice. This information will help understanding habitat use by bonobos in the Western region, and should allow us to come up with specific management measures to be adopted by logging concessions, WWF and ICCN as part of the region’s conservation program

Eco-éthologie de la population de bonobos récemment découverte dans l’ouest de la République Démographique du Congo

The bonobo, Pan paniscus, an endemic primate of the DRC, forms with the chimpanzee, Pan troglodytes, the pair of species closest to humans. Classified as “Endangered” by the IUCN, it’s seriously threatened by the degradation of the forests. Only the creation of protected areas large enough and properly managed can improve its status but requires a good knowledge of the eco-ethology of the local populations. Our project will focus on studying a bonobo population recently discovered in the region of the Lake Tumba, in the west of the DRC. It is characterized by densities never encountered elsewhere, and a preliminary study has revealed significant differences in habitat and food resources in comparison to these of eastern populations. We will contribute to a recently established WWF conservation program by gathering eco-ethological data on bonobos, data that will allow identifying areas to protect, their boundaries and management measures to implement. To do this, we will study the diet of bonobos via direct and indirect observations of their behavior. We will also study the party size and its composition and identify underlying environmental factors. We will assess the bonobos’ home range size and pattern of displacement, which we will correlate with the abundance of food resources to determine whether there is a pattern of occupation of time and space specific to this population

Does edge effect influence Bonobos, Pan paniscus, forest use dynamics: a case study in a forest-savannah mosaic of West DR Congo

Our study helps understand how fragmented forests affect bonobos forest use. Previous studies already reveal that habitat types influence bonobos’ densities, but forests’ spatial structure could also have an impact. In the current context of deforestation and increasing illegal concessions, approaching such questions should help orient future conservation programs. We focus on the influence of edge effect on bonobos forest use, presuming that they avoid areas with non mature forests and increased human pressure. We travelled along transects (113km total) to define habitat types and to record bonobos indices (tracks, food remains and nesting sites) in 200km² of forests in Southwestern Lake Tumba Region. Our results show that bonobos clearly prefer specific habitats for nesting, and, within these nest-forest types, an understory of Marantaceae Haumania sp. is preferentially chosen. To evaluate edge effect on nesting behavior, we counted nesting sites in 100m distance classes from the forest edge. Our results indicate a uniform distribution of nesting sites, but with a negative edge effect in the first 100m. When we analyzed tracks and food remains distribution, we didn’t find any habitat type preferences or any edge effect. These results indicate that, although bonobos are known to favor dense forests, they can also adapt to fragmented forests environment. Habitat types appear to be more relevant to understand their distribution and range