|Scientific Name:||Pan paniscus Schwarz, 1929|
|Taxonomic Source(s):||Mittermeier, R.A., Rylands, A.B. and Wilson D.E. 2013. Handbook of the Mammals of the World: Volume 3 Primates. Lynx Edicions, Barcelona.|
The Bonobo is also known as the Gracile Chimpanzee; formerly it was known as Pygmy Chimpanzee and Dwarf Chimpanzee. Population genetics suggest that Bonobos have a stable population history (Eriksson et al. 2004, Schubert et al. 2013), and that gene flow between populations is constrained by the larger riverine barriers (although Bonobos regularly enter water, they do not swim).
|Red List Category & Criteria:||Endangered A4bcd ver 3.1|
|Assessor(s):||Fruth, B., Hickey, J.R., André, C., Furuichi, T., Hart, J., Hart, T., Kuehl, H., Maisels, F., Nackoney, J., Reinartz, G., Sop, T., Thompson, J. & Williamson, E.A.|
|Reviewer(s):||Mittermeier, R.A. & Rylands, A.B.|
|Contributor(s):||African Wildlife Foundation, Benishay, J., Bila-Isia, I., Butynski, T.M., Coxe, S., Dupain, J., Eriksson, J., Guislain, P., Hashimoto, C., Hohmann, G., Hurley, M., Ilambu, O., Mulavwa, N., Ndunda, M., Omasombo, V., Peereboom, Z., Scherlis, J., Serckx, A., Steel, L., Stevens, J., Verhage, B., Vosper, A., Wildlife Conservation Society & World Wildlife Fund|
Due to high levels of illegal hunting, and habitat destruction and degradation, Pan paniscus is estimated to have experienced a significant population reduction in the last 15–20 years and it is thought that this reduction will continue for the next 60 years. Currently, by far the greatest threat to the Bonobo's survival is poaching for the commercial bushmeat trade. It has been estimated that nine tons of bushmeat are extracted daily from a 50,000-km² conservation landscape within the Bonobo’s range. Not only is there is a massive demand for bushmeat stemming from the cities, but rebel factions and poorly-paid government soldiers add to that demand, at the same time facilitating the flow of guns and ammunition (Fruth et al. 2013). In some areas, local taboos against eating Bonobo meat still exist, but in others, these traditions are disintegrating due to changing cultural values and population movements. Stricter enforcement of wildlife laws and more effective management are urgently needed.
Habitat loss through deforestation and fragmentation ranks second. Much of the forest loss in this region is caused by slash-and-burn subsistence agriculture, which is most intense where human densities are high or growing. Logging and mining do not yet occur on an industrial scale in the Bonobo’s range, but in future, industrial agriculture is very likely to become a serious threat. Minimising the conversion of intact forest to human-dominated land uses, will be critical for the future survival of Bonobos. Countrywide factors contributing to the decline include the mobility of growing human populations, opening markets, commercial exploitation of natural resources and road construction. As in the past, the survival of Bonobos will be determined by the levels of poaching and forest loss—threats that have been shown to accompany rapid growth in human populations and political instability (Nackoney et al. 2014). Due to their slow life history and a generation time estimated to be 25 years, Bonobo populations cannot withstand high levels of offtake. The population decline over a three-generation (75 year) period from 2003 to 2078 is likely to exceed 50%, hence qualifying this taxon as Endangered under criterion A.
|Previously published Red List assessments:|
Pan paniscus has a discontinuous range in the low-lying central basin of Equatorial Africa, south of the Congo River. Its range extends from the Lualaba River in the east, to the Kasai/Sankuru rivers in the south, and to the west as far as the Congo River just 300 km north of Kinshasa (Manzano forest) and around Lake Tumba/Lake Mai-Ndombe (Tumba-Ledima Reserve). The potential geographic range is approximately 563,330 km²; however, only 28% (156,211 km²) of this area is suitable for Bonobos (Hickey et al. 2013). Four geographically-distinct Bonobo strongholds have been identified (IUCN and ICCN 2012):
Additional surveys are needed to better determine the species’ overall distribution and abundance.
Native:Congo, The Democratic Republic of the
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||The size of the Bonobo population is uncertain because only 30% of its historic range has been surveyed. Estimates from the four known Bonobo strongholds, based around protected areas, suggest a minimum population of 15,000–20,000 individuals (IUCN and ICCN 2012, IUCN SSC A.P.E.S. database 2016). Although Hickey et al. (2013) compiled and analysed all Bonobo survey data collected between 2003 and 2010, the survey coverage was too patchy to allow the total number of Bonobos to be estimated.|
Sop et al. (in prep.) used spatial modelling to investigate trends in Bonobo nest encounter rates on recce and standard line transect surveys carried out in two different periods. Data were available from eight sites, covering a total area of 16,500 km². Site-specific change estimates were weighted according to population size, and then change in nest encounter rates between different years was used as a proxy for Bonobo population change. Rate of change was estimated using two approaches: site-level Generalized Linear Models (GLMs); and a simple exponential population change model (ExpM). Sop et al. estimated an annual decline of 5.95% with a total decline of 54.9% between 2003 and 2015 (95% confidence interval: -17.6% to +6.4% and -18% to +0.001% for the GLM and ExpM, respectively). Under the same conditions, the expected decline in abundance over one, two and three generations (25, 50 and 75 years respectively) would be 85.6%, 97.9% and 99.7%, respectively. However, not all sites experienced significant declines in Bonobo abundance. The Lokofa Sector of Salonga National Park, for example, has ecoguards deployed throughout and was the best protected of the eight sites in the analysis (WCS 2015). Although Sop et al.’s assessment incorporated data from both protected and non-protected areas, the total coverage was limited by data availability. In addition, the preliminary model had limitations with regard to the representativeness of sites and data availability, such as disproportionate sampling effort between years; and lack of data on seasonality, nest production, re-use and decay rates. If few nests are located and sample size is low, then precision tends to be poor, leading to weak detection of trends. Although a drop in abundance between the two time periods was detected, the small number of paired samples did not produce population sizes. The range-wide data required will eventually show areas considered to be suitable, but from which Bonobos are absent, and perhaps presence of Bonobos in areas not yet surveyed. Despite uncertainty around the modelled rate of decline, a strong negative trend is apparent in Sop et al.’s analysis. Even with an annual rate of decline of only 1%, total losses would exceed 50% over three generations, underscoring the need for monitoring of Bonobo populations and threats.
|Current Population Trend:||Decreasing|
|Habitat and Ecology:||The geographic range of Pan paniscus is characterised by undulating terrain with elevations between 300 and 700 m asl and a humid climate (Fruth et al. 2013). Bonobos inhabit closed, moist, mixed, mature and secondary forests as well as forest-savannah mosaics (ibid.). In the eastern and southern parts of their range, Bonobos occupy a mosaic of moist tropical forest, dry forest, savannah woodland, marshy grassland and swamp forest, yet they also require access to relatively-undisturbed mature forests. If available, Bonobos prefer primary forests and seasonally-inundated swamp forests, foraging in small streams and breast-deep ponds (Narat 2014, Serckx 2014).|
Bonobos are diurnal and semi-terrestrial. They live in multimale-multifemale, fission-fusion communities, usually made up of 30–80 individuals. A single community occupies a home range of 20–60 km², and there is extensive overlap between the ranges of different communities (Fruth et al. 2013). Bonobos are omnivorous; over 50% of their diet is comprised of fruits and seeds, which are supplemented with leaves, stems, shoots, pith, bark, flowers, truffles, fungus, and honey (Hohmann et al. 2006). They appear to be more dependent on terrestrial herbaceous vegetation, including aquatic plants, than chimpanzees. Bonobos have occasionally been documented hunting and eating vertebrates (e.g., duikers, primates; Hohmann and Fruth 2008) and invertebrates (e.g., termites, caterpillars; Kano 1992). Bonobos build new nests to sleep in each night and sometimes make day nests in trees at heights of 5–50 m (Fruth 1995). It has been reported that Bonobos also make ground nests (Kano 1983, Guislain and Reinartz pers. comm). Their role as seed dispersers is critical for forest regeneration (Tsuji et al. 2010, Beaune et al. 2013).
There is no birth season. Gestation is about eight months. Interbirth interval at Wamba (1976–1996) averages 4.8 years, and females average 0.18 offspring per year of their adult life. Physical maturation is slow with infants being weaned shortly before birth of the next offspring. Infant and juvenile mortality is low, with 73% of offspring surviving to age six (Furuichi et al. 1998). Females migrate aged 6–13 years, settling into a new community when they start cycling at 9–12 years. They produce their first offspring at 13–14 years of age (Furuichi et al. 2012). One generation is estimated to be 23–25 years (Myers Thompson 1997, T. Furuichi pers. comm. 2007, Langergraber et al. 2012).
|Generation Length (years):||23-25|
|Movement patterns:||Not a Migrant|
|Use and Trade:||
Killing or capture of Bonobos for any purpose is against national and international laws.
The major threats to Bonobos include: poaching (mainly for bushmeat and for some medicinal purposes); residue from civil warfare (availability of modern weaponry and ammunition; military-sanctioned hunting); human-induced habitat alteration (commercial logging and agriculture, traditional slash-and-burn agriculture, fallow land); human population growth and migration; and lack of education (insufficient awareness among urban and rural communities that hunting and eating Bonobos is unlawful). Bonobos reproduce slowly, and thus their populations are particularly susceptible to direct losses caused by humans.
Pan paniscus is listed on Appendix I of CITES and as Class A under the African Convention on the Conservation of Nature and Natural Resources. Bonobos are protected by national and international laws throughout their range, and the majority are found in national parks (IUCN SSC A.P.E.S. database 2016). However, most protected areas lack resources and suffer from poorly-controlled poaching, and enforcement is generally weak.
An IUCN and ICCN (2012) Bonobo conservation strategy (http://www.primate-sg.org/bonobo) outlines five intervention strategies with objectives and conservation actions centred on the Bonobo ‘strongholds’, which are to be implemented by 2022:
In sum, for protection of Bonobos to be effective, commercial poaching must be halted, intensification rather than expansion of local agriculture must be supported, and local industries must be actively persuaded to support rather than subvert conservation objectives. The most urgent conservation measures needed are those that enhance Bonobo survival in situ: effective law enforcement; long-term project presence on the ground; population monitoring; and education at all levels of society.
|Errata reason:||This is an errata version of the 2016 assessment to correct some minor typos and grammatical errors in the Threats and Conservation Actions sections.|
|Citation:||Fruth, B., Hickey, J.R., André, C., Furuichi, T., Hart, J., Hart, T., Kuehl, H., Maisels, F., Nackoney, J., Reinartz, G., Sop, T., Thompson, J. & Williamson, E.A. 2016. Pan paniscus. (errata version published in 2016) The IUCN Red List of Threatened Species 2016: e.T15932A102331567.Downloaded on 17 October 2017.|
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