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See detailBonobo nest site selection and the importance of predictor scales in primate ecology
Serckx, Adeline ULiege; Huynen, Marie-Claude ULiege; Beudels-Jamar, R. C. et al

in American Journal of Primatology (2016), 78(12), 1326-1343

The role of spatial scale in ecological pattern formation such as the geographical distribution of species has been a major theme in research for decades. Much progress has been made on identifying ... [more ▼]

The role of spatial scale in ecological pattern formation such as the geographical distribution of species has been a major theme in research for decades. Much progress has been made on identifying spatial scales of habitat influence on species distribution. Generally, the effect of a predictor variable on a response is evaluated over multiple, discrete spatial scales to identify an optimal scale of influence. However, the idea to identify one optimal scale of predictor influence is misleading. Species-environment relationships across scales are usually sigmoid increasing or decreasing rather than humped-shaped, because environmental conditions are generally highly autocorrelated. Here, we use nest count data on bonobos (Pan paniscus) to build distribution models which simultaneously evaluate the influence of several predictors at multiple spatial scales. More specifically, we used forest structure, availability of fruit trees and terrestrial herbaceous vegetation (THV) to reflect environmental constraints on bonobo ranging, feeding and nesting behaviour, respectively. A large number of models fitted the data equally well and revealed sigmoidal shapes for bonobo-environment relationships across scales. The influence of forest structure increased with distance and became particularly important, when including a neighbourhood of at least 750 m around observation points; for fruit availability and THV, predictor influence decreased with increasing distance and was mainly influential below 600 and 300 m, respectively. There was almost no difference in model fit, when weighing predictor values within the extraction neighbourhood by distance compared to simply taking the arithmetic mean of predictor values. The spatial scale models provide information on bonobo nesting preferences and are useful for the understanding of bonobo ecology and conservation, such as in the context of mitigating the impact of logging. The proposed approach is flexible and easily applicable to a wide range of species, response and predictor variables and over diverse spatial scales and ecological settings. © 2016 Wiley Periodicals, Inc. [less ▲]

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See detailEcosystem services provided by a large endangered primate in a forest-savanna mosaic landscape
Trolliet, Franck ULiege; Serckx, Adeline ULiege; Forget, Pierre-Michel et al

in Biological Conservation (2016)

Forested landscapes are increasingly affected by human activities, but little is known about the role of large endangered frugivores as seed dispersers in such ecosystems. We investigated the role played ... [more ▼]

Forested landscapes are increasingly affected by human activities, but little is known about the role of large endangered frugivores as seed dispersers in such ecosystems. We investigated the role played by the bonobo (Pan paniscus) in a human-altered forest-savannamosaic in Democratic Republic of the Congo. The studied groups are part of a community-based conservation programme but live at the interface with human activities. We identified dispersed species via faecal analysis, classified them into a regeneration guild and a seed size category, determined the effect of gut transit on seed germination, and the habitat use of bonobos. Bonobos dispersed intact seeds of 77 species, 80.8% of which were large-seeded (≥10mmlong), ofwhich fewcan be dispersed by sympatric frugivores. They dispersed a majority (49%) of shade-bearers that thrive in forest understory with limited amount of light, all of whichwere large-seeded. Transit had an overall positive effect on seed germination. Bonobos used various habitat types, showing preferences for understorywith intermediate light availability and dominated by woody or herbaceous vegetation. This dispersal pattern probably enhances recruitment of shadebearers, and we thus hypothesized that those species benefited from directed dispersal by bonobos. This threatened frugivore provides unique dispersal services and likely plays a paramount functional role in the regeneration of late successional forests in this mosaic landscape. Management plans should pay particular attention to the role of large and rare frugivores in human-dominated regions as their disappearance could disrupt forest succession to a climax state. [less ▲]

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See detailSeeing Central African forests through their largest trees
Bastin, Jean-François ULiege; Barbier, Nicolas; Réjou-Méchain, Maxime et al

in Scientific Reports (2015), 5

Large tropical trees and a few dominant species were recently identified as the main structuring elements of tropical forests. However, such result did not translate yet into quantitative approaches which ... [more ▼]

Large tropical trees and a few dominant species were recently identified as the main structuring elements of tropical forests. However, such result did not translate yet into quantitative approaches which are essential to understand, predict and monitor forest functions and composition over large, often poorly accessible territories. Here we show that the above-ground biomass (AGB) of the whole forest can be predicted from a few large trees and that the relationship is proved strikingly stable in 175 1-ha plots investigated across 8 sites spanning Central Africa. We designed a generic model predicting AGB with an error of 14% when based on only 5% of the stems, which points to universality in forest structural properties. For the first time in Africa, we identified some dominant species that disproportionally contribute to forest AGB with 1.5% of recorded species accounting for over 50% of the stock of AGB. Consequently, focusing on large trees and dominant species provides precise information on the whole forest stand. This offers new perspectives for understanding the functioning of tropical forests and opens new doors for the development of innovative monitoring strategies. [less ▲]

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See detailFeeding ecology of bonobos living in forest-savannah mosaics: diet seasonal variation and importance of fallback foods
Serckx, Adeline ULiege; Kühl, Hjalmar; Beudels-Jamar, Roseline et al

in American Journal of Primatology (2015)

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See detailNest grouping patterns of bonobos (Pan paniscus) in relation to fruit availability in a forest-savannah mosaic
Serckx, Adeline ULiege; Huynen, Marie-Claude ULiege; Bastin, Jean-François ULiege et al

in PLoS ONE (2014)

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 ... [more ▼]

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. [less ▲]

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See detailCould bonobos, Pan paniscus, influence forest re(colonization) in a forest-savana mosaic?
Trolliet, Franck ULiege; Serckx, Adeline ULiege; Huynen, Marie-Claude ULiege et al

in Folia Primatologica: International Journal of Primatology (2013, September 12)

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See detailDynamic of seed dispersal by large frugivores in a forest-savanna mosaic subject to anthropic pressure in Western D.R. Congo
Trolliet, Franck ULiege; Serckx, Adeline ULiege; Huynen, Marie-Claude ULiege et al

Poster (2013, April 05)

The Western Congolian forest-savanna mosaic is an ecotone subject to anthropogenic as well as natural fragmentation. Its forests have thus a considerable proportion of edges. This vegetation structure is ... [more ▼]

The Western Congolian forest-savanna mosaic is an ecotone subject to anthropogenic as well as natural fragmentation. Its forests have thus a considerable proportion of edges. This vegetation structure is likely to impact animal and plant communities and its dynamics such as animal mediated seed dispersal. Synergetically, activities such as bush meat hunting deplete large frugivores populations and thus decrease recruitment potential of the plants they disperse. Indeed, zoochory is known to be of great importance for tropical forests and a number of studies proved that large-seeded tree species closely depend on large frugivores for their regeneration. In such a context, we aim to understand how forest edges affect the dynamics of seed dispersal. More precisely, we wonder if the interactions between large seeds and their dispersers and predators are affected when closer to edges and how this can impact plant regeneration capacity. Also, we wonder if the dispersal and regeneration of large-seeded tree species depend on a few disproportionally important frugivores species. Bonobos, Pan paniscus, are among the largest frugivores left in the area and thus likely to be disproportionally important seed dispersers, though, their role as seed dispersers has yet been little investigated. We thus focus on the qualitative role for seed dispersal of the potentially keystone and umbrella ape species, the bonobo. To answer those questions, we study the main steps characteristics of large-seeded tree species regeneration process; namely quantitative seed dispersal, seed deposition pattern, germination capacity after transit in frugivore’s gut and, seed and seedling fate. By studying five different tree species at varying distances from forest edge, we aim to drive an inter-species comparison and to highlight the effect of forest edge on the regeneration process. We first quantify the seed production for each tree species and then evaluate the quantitative capacity of seed dispersal. By combining direct focal observations and camera trapping, we are able to highlight variations in composition of dispersers community and their respective contribution to seed dispersal. A literature review on each disperser species’ seed retention time and habitat use will allow the computation of the seed dispersal kernels. We will also evaluate the effect of seed ingestion by the bonobo on its germination capacity: seeds will be collected from dung to evaluate the effect of seed ingestion on the rate and velocity of germination. Finally, we will study the predation pressure exerted on dispersed and non-dispersed seeds and seedlings by setting up two sets of seeds below the canopy of parent trees and away from any conspecific trees. One set will be dispersed unprotected to seed predators; another one will be enclosed in a cage and permit seeds to germinate, allowing us to evaluate the herbivores pressure on seedlings. [less ▲]

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See detailResearch Contributions from Lola Ya Bonobo
André, Claudine; Songrady, Judy; Serckx, Adeline ULiege et al

in Folia Primatologica: International Journal of Primatology (2013), 84

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See detailBehavioural Ecology of Bonobos (Pan paniscus) in the Forest-Savannah Mosaics of Western Democratic Republic of Congo
Vimond, Marie; Serckx, Adeline ULiege; Beudels-Jamar, Roseline et al

in Folia Primatologica: International Journal of Primatology (2013)

The long-term survival of the Endangered bonobo (IUCN, 2012) will depend on well thought out conservation programmes that need to be built both upon the species’ ecological requirements and local socio ... [more ▼]

The long-term survival of the Endangered bonobo (IUCN, 2012) will depend on well thought out conservation programmes that need to be built both upon the species’ ecological requirements and local socio-economics realities. Yet there is still a lot to find out, including information on the species geographical distribution. In 2005, the presence of a western population was confirmed in the forest-savannah mosaic in the south-western part of the Lake Tumba Landscape. With the exception of an early study carried out in Lukuru, the species is mainly known from lowland rainforest research sites in the Cuvette Centrale. The western forest-savannah mosaic is an ecotone with a marked seasonal pattern, a high variability of habitats and monthly variations in fruit production. All this leads to spatio-temporal variation of food availability. In order to increase studies and monitoring of this unique population, WWF initiated a habituation process of two groups of bonobos 6 years ago. The groups are now semi-habituated, making the collection of direct daily observations possible. Our objective is to describe the behavioural strategies developed by this population in order to cope with spatio-temporal variations of food availability. This will be approached by identifying daily activity, ranging and grouping patterns, in order to understand how they affect social structure. It should also allow us to define the use of savannahs. Our findings will help determine specific conservations measures for this endangered species. [less ▲]

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See detailDevastating Decline of Forest Elephants in Central Africa.
Maisels, Fiona; Strindberg, Samantha; Blake, Stephen et al

in PLoS ONE (2013), 8(3),

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 ... [more ▼]

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. [less ▲]

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See detailOptimizing scale search in species distribution models
Serckx, Adeline ULiege; Huynen, Marie-Claude ULiege; Beudels-Jamar, Roseline et al

in Folia Primatologica: International Journal of Primatology (2013), 84

The influence of spatial scale on ecological processes and pattern formation, such as species distribution is a major research topic since decades. It has become even more relevant in the context of ... [more ▼]

The influence of spatial scale on ecological processes and pattern formation, such as species distribution is a major research topic since decades. It has become even more relevant in the context of global change. In many studies the influence of a predictor on a response derived over multiple and discrete spatial scales is evaluated. Due to inherent issue of multiple testing, this approach can be problematic. In this study on bonobos distribution, we suggest a 3-steps procedure that overcomes this problem. It takes into account the decay of a predictor by using a weighting function of distance to the observation of interest. We use variables to account for human pressure, food availability, patchy structure of the forest and nesting sites re-use. In a first step, we run a model with a fixed scale for every predictor based on expert opinion. For significant variables, we derive then in a second step the distance weighted influence over a range of scales. This helps to narrow down the search for the final model parameter estimates. Findings indicate that bonobo distribution is driven on the intermediate scale by forest patches structure. Food availability explains their abundance only at smaller scales. Those results demonstrate the sadly well-known influence of habitat fragmentation on animals’ density and distribution but also highlight the importance to understand influences of scale, the animal perceptions of their environment, by using appropriate statistical procedures. Our method can be particularly useful to formulate specific management hypotheses for conservation. Furthermore, its principles can be of use to other types of studies, such as behavior. [less ▲]

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See detailDoes edge effect influence Bonobos, Pan paniscus, forest use dynamics: a case study in a forest-savannah mosaic of West DR Congo
Serckx, Adeline ULiege; Beudels-Jamar, Roseline; Huynen, Marie-Claude ULiege

Conference (2012)

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 ... [more ▼]

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. [less ▲]

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See detailBonobos, Pan paniscus, in the forest-savannah mosaics of West DR Congo: does spatial structure influence the forest use dynamics?
Serckx, Adeline ULiege; Huynen, Marie-Claude ULiege; Beudels-Jamar, Roseline

Conference (2012)

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 ... [more ▼]

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 concessions [less ▲]

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See detailEco-Ethology of bonobos, Pan paniscus, in West Democratic Republic of Congo: why are such data so important for long-term conservation programs?
Serckx, Adeline ULiege; Huynen, Marie-Claude ULiege; Beudels-Jamar, Roseline

in American Journal of Primatology (2011), 73

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 ... [more ▼]

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. [less ▲]

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See detailEco-Ethology of bonobos, Pan paniscus, in West Democratic Republic of Congo; why are critical data so important for long-term conservation programs?
Serckx, Adeline ULiege; Huynen, Marie-Claude ULiege; Beudels-Jamar, Roseline

Conference (2011)

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 ... [more ▼]

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. [less ▲]

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See detailEco-éthologie de la population de bonobos récemment découverte dans l’ouest de la République Démographique du Congo
Serckx, Adeline ULiege; Huynen, Marie-Claude ULiege; Beudels-Jamar, Roseline

Conference (2009)

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 ... [more ▼]

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. [less ▲]

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