Bonobo (Pan paniscus) Conservation Strategy 2012–2022

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already been emptied of their large and medium-sized vertebrates. As wildlife populations are 

progressively impoverished, hunters move further and further into remote forest blocks in search 

of the remaining intact wildlife populations. Access to large vertebrates enables hunters to obtain 

returns on their investment in terms of hunting effort. Extrapolations of offtake from bushmeat 

surveys in the bonobo’s range reveal highly unsustainable hunting. In TL2, before the imposition 

of the region’s first closed season and efforts to directly combat bonobo hunting, it was estimated 

that 270 bonobos were killed annually from a hunting catchment of about 12,000 km²

 

to provi-

sion over eight bushmeat markets supplying the city of Kindu (Hart & Hart 2011). In the remote 

Salonga-Lukenie-Sankuru landscape it has been estimated that every day nine tons of bushmeat 

are extracted from an area of 50,000 km² (Steel et al. 2008). Over a 4-month period, field teams 

uncovered evidence of the killing of 13 bonobo and live trafficking of three orphans. In addition, 

bonobo meat was found to be for sale on multiple occasions at two markets and two crossing 

points (Steel et al. 2008).

A few exceptions exist where local taboos forbidding the killing and consumption of bonobos have 

been instrumental in the preservation of specific local populations (Inogwabini et al. 2008; Lingomo 

et al. 2009). However, in many areas these taboos are changing rapidly due to years of war and 

civil unrest, the influx of immigrants, and the near total breakdown of law and order and of previous 

social norms (Fruth et al. 2008).

4.1.1.2 Habitat Destruction and Fragmentation

Most habitat destruction in the bonobo’s range has resulted from slash-and-burn subsistence agri-

culture, which is most intense where human densities are highest and growing. Human settlements 

are concentrated along the transport and communications network (rivers and roads). This pattern 

of land use leads to the progressive fragmentation of the forest massif, but with the post-war reha-

bilitation of infrastructure there will be a considerable increase in habitat loss and degradation with 

the expansion of such commercial endeavours as industrial logging, agriculture (especially oil palm 

plantations), mining and oil extraction, that will, besides, fuel and facilitate the bushmeat trade.

Annual forest loss in DRC is low compared to tropical forests in other regions of the world (Hansen 

et al. 2011), although it increased from 0.22% per year for 2000–2005 to 0.25% for 2005–2010 

(Potapov et al. 2012). Gross forest loss in DRC from 2000 to 2012 totalled 2.3% of forest area, 

with an increase of 13.8% between 2000–2005 and 2005–2010. The increase has been greatest 

in primary forest loss, where the rate almost doubled between the two time periods (Potapov et 

al. 2012).

Following the analysis of a suite of factors, including land-use patterns, human activities and habi-

tat suitability, Junker et al. (2012) estimated that there has been a 29% reduction in suitable condi-

tions within the bonobo’s range since the 1990s. At the rangewide scale, deforestation has been 

most severe along the extensive river network that serves as the transportation system, because 

rivers are the primary access route for penetrating into the forests and moving timber and other 

goods out to urban centres.

4.1.1.3 Disease

The risk of epidemics spreading among wild bonobos is a cause of serious concern. Diseases 

that pose a risk to bonobos include infectious natural pathogens (e.g., Ebola) and human-borne 

diseases, such as respiratory ailments. Many diseases and parasites can affect bonobos, including 

respiratory, gastrointestinal or skin pathogens, which vary in severity from latent to fatal (Cawthon 

Lang 2010). Despite the absence of direct reports of massive die-offs of bonobos, a highly virulent 

epidemic (e.g., Ebola Hemorrhagic Fever) could devastate bonobo populations, considering their 

highly cohesive social structure, and high rates of physical contact amongst group members, 

resulting in rapid contagion rates across a population. In Gabon and the Republic of Congo, the 

Ebola virus has caused massive declines in chimpanzee and gorilla populations, with specific 

areas experiencing up to 90% decreases of their great ape populations (Bermejo et al. 2006; 

Caillaud et al. 2006; Huijbregts et al. 2003; Leroy et al. 2004; Walsh et al. 2003). While it is difficult 

to separate the impact of the epidemics from that of the other threats or to obtain precise pre-post 

Ebola numbers, Walsh et al. (2003) estimated that the Ebola virus was responsible for a decline of 

about one third of the entire population of gorillas in Gabon.

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Human population growth and the resulting increase in hunting means that bonobos and humans 

are in increasingly close proximity. Disease transmission is also a concern in other situations where 

bonobos and humans come into close contact: tourism, the habituation of research groups and 

sanctuaries for orphaned great apes. Disease could be a very serious threat to bonobos, and 

should be monitored as such.

Box 2. Analysis of Antibodies and DNA using Faecal Samples from Wild Great Apes

With support from the Environmental Research & Technology Development Fund of the Japanese Ministry of the Environment, 

a research group at the Primate Research Institute (PRI) of Kyoto University has developed new methodologies for detecting 

variations in DNA and antibodies using faecal samples from wild bonobos. In collaboration with research and conservation 

groups, faecal samples were collected from bonobo populations at seven sites that cover much of their geographic range: 

Iyondji, Lac Tumba, Lomako, Malebo, Salonga, TL2 and Wamba. PRI is undertaking analyses of the prevalence of human 

infectious diseases and genetic structure in each bonobo population. These analyses for screening will contribute to the 

development of efficient plans for the conservation of wild great ape populations. The research group at PRI would be happy 

to collaborate with any researchers working towards similar goals or to provide technical advice. Contact Takeshi Furuichi 

([e-mail]) for further information.

Screening of antibodies for zoonotic pathogens in wild bonobo populations

Infectious diseases, including those transmitted from humans to great apes, are one of the greatest threats to the survival of 

great apes, with the potential to cause local extinctions. As yet, we do not adequately understand the mechanisms of trans-

mission or know enough about the prevalence of different pathogens in the environment, and it is difficult to establish effec-

tive ways to prevent disease transmission. The occurrence of pathogens and frequency of disease outbreaks differ between 

sites and species of great ape, and may change over time. Respiratory disease outbreaks among the Wamba bonobos have 

only been observed since the war in Congo (1996–2002), when displaced people and soldiers were moving through the 

forest. To examine the prevalence of pathogens in wild great ape populations, we have developed new methods for detecting 

IgA antibodies in faecal samples. A preliminary examination of samples from four bonobo populations found that about one 

quarter of wild bonobos have specific IgA antibodies for all of the human respiratory viruses that we tested for. Furthermore, 

there were large inter-site differences in the positive ratio of antibodies detected. While high positive ratios at some sites sug-

gest that disease transmission between humans and bonobos and/or among the bonobo populations is frequent, low positive 

ratios at other sites indicate that those bonobos are ‘naïve’ to human diseases – that they have had no prior exposure to these 

viruses and would, therefore, be at greater risk of outbreaks if such viruses entered the population. The required means of 

prevention of disease transmission may differ for each bonobo population according to the types and prevalence of viruses 

that occur there. Monitoring of IgA antibodies will help establish effective and efficient guidelines for disease prevention in 

wild great ape populations. This study (Yoshida et al. in prep.) was supported by the Japanese Ministry of the Environment.

Tomoyuki Yoshida, Hirofumi Akari & Takeshi Furuichi

Genetic diversity of wild bonobo populations

Analyses of genetic diversity provide invaluable information for conservation planning with respect to population viability. We 

have recently developed new methods for detecting DNA in faeces, and were able to analyze samples from seven bonobo 

populations (see above). A preliminary analysis of mitochondrial DNA (mtDNA) revealed that these populations can be grouped 

into three clusters: a western cluster that includes Lac Tumba and Malebo, a central cluster that includes Lomako, Wamba, 

Iyondji and Salonga, and an eastern cluster that includes TL2. While the central cluster showed the largest nucleotide diversity, 

the eastern cluster had unique haplotypes of mtDNA. While it is important to conserve all bonobo populations, we suggest that 

it is particularly important to conserve the central cluster for preservation of a wide variety of genes and to conserve the eastern 

cluster for their unique genes. When we compared the populations, we found that those that are more isolated (Malebo, Wamba 

and TL2) had the lowest genetic diversity, which suggests that they may face a higher risk of extinction. Analysis of the genetic 

diversity among various bonobos populations, together with detailed information about their geography and biology, provides 

an important component in conservation planning and in assessing the value of each subpopulation. This study (Kawamoto et 

al. in press) was supported by the Japanese Ministry of the Environment.

Yoshi Kawamoto, Hiroyuki Takemoto & Takeshi Furuichi

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