Bonobo

SOCIAL ORGANIZATION AND BEHAVIOR

Bonobos live in fission-fusion social groups where a large community of individuals separate into smaller groups, or parties, of variable size and composition. These “unit-groups” range from lone individuals to groups of 20 or more bonobos (Badrian et al. 1984; White 1988, 1996). These groups are patrilineal and the unit group is multi-male/multi-female, though the ratio of males to females is variable. At seven to nine years old, females emigrate from their natal groups to another group where they spend much time trying to initiate social interactions with dominant older adult females (Furuichi 1989). It is important for young, immigrant females to develop relationships with other females in their new groups because this is one of the strongest relationships in bonobo society. Unlike chimpanzees, females tend to have more cohesion with other females than with males, though there is evidence that as group size increases, cohesion between males and females increases (White 1988; 1996). Females obtain rank as they age and have offspring, especially males. Their sons often have corroborating rank as they mature and as the adult female becomes more central to the group (White 1996).

Because females within the community are unlikely to be related, it is unusual that female bonobos show such strong affiliation with one another in parties and within communities. Paradoxically, males in bonobo communities are related to one another and show little affiliative behavior (White 1996). The duration and intensity of relationships that develop between male and female bonobos are not simply based on sexual attraction. Adult males and females associate for reasons besides mating that include kinship and rank acquisition (White 1996; Hohmann et al. 1999). Though females emigrate from their natal groups, molecular analyses of the genetic relatedness between community members at the Lomako field site recognized mother-son pairs and adult half-siblings associated more frequently than unrelated mixed-sex dyads (Hohmann et al. 1999). Males also associate with females for rank acquisition because females dominate the social environment. Females that have strong bonds keep males away from food and often attack males, biting off their fingers and toes (de Waal 1997). If a male is to achieve alpha status in a bonobo group, he must be accepted by the alpha female.

One of the most significant and defining characteristics of bonobo societies is sexual behavior. Sex serves purposes other than reproduction such as appeasement, affection, social status, erotic games, reconciliation, excitement, and stress reduction (de Waal 1997). Sex occurs in virtually all partner combinations and in a variety of positions. Sex, particularly genito-genital rubbing (G-G rubbing), facilitates and strengthens the bond between female bonobos (de Waal 1997). It is used in food-sharing interactions between females. Nonreproductive copulation is often seen between males and females as well. While males rarely share food, when subordinate females beg for food from dominant males, the likelihood that the male will share is greatly increased if they first copulate (Blount 1990). It is important to remember, though, that sex is primarily a function of stress reduction at feeding sites not as currency for food (Blount 1990).

REPRODUCTION

Menarche occurs in female bonobos between ages six and eleven years (Vervaecke et al. 1999). Female bonobos exhibit obvious sexual swellings throughout their adult lives and the swelling of the sex skin is an external indicator of endocrinological processes. Only juveniles and mothers of very young infants exhibit truly flat sex skins. The swelling can be categorized into four stages over the menstrual cycle: preswelling, swelling, postswelling, and menses. Ovulation, though, is not perfectly correlated with swelling size (Thompson-Handler et al. 1984; Reichert et al. 2002). This extended period of swelling coupled with ambiguity in peak receptivity may have significance in the evolution of such promiscuous sexual behavior (de Waal 1997; Reichert et al. 2002). In males, it is difficult to determine pubertal onset and fertility onset is largely unknown (Watts & Pusey 1993). It is estimated that males reach sexual maturity around nine years when body size and testes greatly enlarge (Kuroda 1989).

As a tactic to avoid inbreeding, adolescent female bonobos emigrate from their natal groups at around seven years-old and join another group where they will produce their first offspring by the age of 13 or 14 (Rowe 1996; de Waal 1997). After their first offspring, the interbirth interval is four to six years (Kano 1992; Rowe 1996; de Waal 1997). Bonobos resume swelling cycles within one year after parturition and though they rarely become pregnant, have been seen nursing two infants of different ages (Kano 1996; de Waal 1997; Furuichi et al. 1998).

Data suggest that there is a birth peak during the light rainy season between March and May of each year (Furuichi et al. 1998). This timing is significant because it is directly after the driest part of the year and may have an influence on infant survival. In fact, immature bonobo mortality rates at Wamba are lower than for chimpanzees in sparser environments. With only 18.2% of the bonobos dying by age five and only 27.3% dying by age six, there may be a link between relative abundance of fruits and herbaceous foods and infant survival rates (Furuichi et al. 1998).

PARENTAL CARE

Because of the promiscuous mating behavior of female bonobos, there is a great deal of paternal uncertainty. If a male cannot be sure which offspring are his, he is less likely to invest any time or energy caring for them. It is because of this lack of certainty that the entirety of parental care in bonobos is assumed by the mothers (de Waal 1997). That is not to say that adult males are not attentive to infants in the unit-group, in fact, there is very little aggression directed towards bonobo infants by adult males in the group and infanticide has never been recorded (Kuroda 1989; de Waal 1997).

Like all primates, bonobos exhibit a prolonged maturation period that is necessary for behavioral plasticity, strong mother-offspring relationship, and social development (Kuroda 1989). Bonobos, though, when compared to chimpanzees, have a particularly slow rate of development, and it is reported that bonobo mothers are more attentive to their offspring than chimpanzee mothers. In their first years, bonobos maintain close proximity to their mothers as they ride ventrally. Never before three months of age do they leave their mother and even at six months, they are rarely seen more than one meter away from her (Kuroda 1989). By 10 months the bonobo infant ventures about three to four meters (9.84 to 13.1 ft) from its mother, but any further and the mother will bring the infant back to her side. At one year, bonobo infants are still unsure as quadrupeds, but can locomote for a few meters. Play develops around two years of age but bonobos are still not a mobile as adults. Not until three years of age do bonobos move as gracefully as adults, and at this age they move more than 10 meters (32.9 ft) from their mothers, but are still close enough to return immediately if frightened or threatened. It is at this age that bonobo infants begin to ride dorsally rather than ventrally on their mothers (Kuroda 1989). Bonobos are not weaned until four or five years of age. They are sustained by nursing for the first year of life, and though they may mouth food, they never consume it in the first year (Kuroda 1989).

As bonobos age, the extent of the bond between mothers and offspring is sex-dependent. Subadult female bonobos begin to distance themselves from their mothers around six to seven years, though they are usually still in the same foraging party. Eventually they will emigrate from their natal group and the bond between mother and daughter is severed (Kuroda 1989). Male bonobos, on the other hand, remain quite close with their mothers through adulthood and a mother’s rank within the group determines her son’s rank as he reaches adulthood (Kuroda 1989; White 1996).

COMMUNICATION

Visual cues are important in primates, especially in the catarrhines, that lack a vomeronasal system. Bonobos have a remarkably expressive face and have a plethora of facial communications. Some of the predominant expressions include: “silent teeth baring,” “tense mouth,” “silent pout,” “duck face,” and “play face,” though these represent only a percentage of the facial expressions seen in bonobos (de Waal 1988). Similar to visual communication, vocal communication is also important in bonobo society. Bonobos have higher pitched voices than chimpanzees and are easily distinguished based solely on sound. The two species do, however, have some overlap in their vocal repertoire (de Waal 1988). Some of the vocal displays noted in bonobos include: “low hooting,” “high hooting,” “contest hooting,” “wieew-bark,” and “greeting grunts” (de Waal 1988). An interesting vocalization that is characteristic of play is the “panting laugh.” This jerky breathing that sounds like laughter and is always accompanied by a “play face” is usually heard during play and tickling (de Waal 1988).

In trying to understand the context of human language evolution, much research has been conducted on bonobos. As a result, scientists have been successful in teaching bonobos the use of lexigrams as a way to communicate with humans. This work was first done with chimpanzees in Georgia at the Yerkes National Primate Research Center, but was made famous by a bonobo named Kanzi. With the help of language researcher Sue Savage-Rumbaugh, Kanzi can understand spoken word and can respond appropriately by using a lexigram. Researchers have not been able to teach apes spoken language because of physiological barriers; mainly the inability to accomplish velopharyngeal closure to produce consonant sounds (Savage-Rumbaugh & Lewin 1994).

SPECIAL NOTES

Bonobos have not traditionally been acknowledged for their use of tools, but they have been noted to self-medicate by leaf swallowing during the peak occurrence of intestinal parasites. Studies during the rainy season, at Iyema and Lomako show an increase in Oesophagostomum infections due to the lifecycle of these parasitic nematodes. This peak is correlated with leaf-swallowing, a behavior not often seen throughout the year (Dupain et al. 2002). This behavior is considered self-medication because bonobos generally chew leaves that they consume as food rather than swallow them whole. The physical action of swallowing leaves with rough surfaces facilitates expulsion of tapeworm fragments (Dupain et al. 2002).

Other interesting behaviors seen in bonobos include cultural differences in play and grooming among captive bonobos. Local variations of behavior in captive settings can be thought of as cultural differences; they are not seen in every captive population and new individuals introduced to groups that practice these diverse behaviors learn them and practice them. For example, at the San Diego Zoo, during grooming sessions between two animals, the bonobo that is grooming stops grooming at regular intervals and claps his or her hands, feet, or hand and foot together making an audible clapping noise. This behavior is the only place in the world where bonobos clap while grooming, and new individuals introduced to the group learn this behavior (de Waal 2001). Another behavior seen only among the San Diego bonobos are play behaviors such as “blind man’s bluff” and “funny faces,” two games played by the young bonobos of the group. In “blind man’s bluff,” a juvenile places an arm over his face or covers his eyes in some way and proceeds to walk along the play structures within the enclosure, often losing his balance or bumping into obstacles. This is a solitary game to begin with, but once a juvenile begins to play, other young bonobos in the group will begin to play (de Waal 2001). Finally, another cultural behavior seen among captive bonobos is a game called “funny faces” in which a solitary young bonobo makes faces for no obvious reason and which are directed at no member of the group (de Waal 2001). These behaviors are seen nowhere outside of the San Diego group of bonobos.

Content last modified: December 1, 2010

Written by Kristina Cawthon Lang. Reviewed by Frans de Waal.

Cite this page as:
Cawthon Lang KA. 2010 December 1. Primate Factsheets: Bonobo (Pan paniscus) Behavior . <http://pin.primate.wisc.edu/factsheets/entry/bonobo/behav>. Accessed 2020 July 29.

INTERNATIONAL STATUS

For individual primate species conservation status, please search the IUCN Red List.
Also search the current scientific literature for primate conservation status (overall as well as for individual species), and visit CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora).

Conservation information last updated in 2010 follows, for comparison:

CONSERVATION THREATS & POTENTIAL SOLUTIONS

Threat: Human Induced Habitat Loss and Degradation

Habitat loss and degradation due to commercial logging, subsistence usage of forest products, and re-emigration into the forest by local human populations is prevalent in DRC and greatly threatens bonobo populations (Dupain et al. 2000). Large-scale commercial logging is responsible for more damage than simply removal of forest cover; some of its byproducts include loss of biodiversity, climate change, desertification, and watershed degradation (Rowe et al. 1992). These indirect environmental consequences are of serious concern for bonobo populations, even at well-established research sites that exist on logging concessions (Oates 1995; Thompson-Handler 1995). There is continuing concern that the Congolese government will begin to rely more heavily on timber extraction as its key economic opportunity and depend on forest resources for fiscal development. Because of these future plans, commercial logging is the perceived to be the largest threat to bonobos in DRC over the long-term (Reinartz & Bila Isia 2001).

More ubiquitous as a cause of habitat loss and degradation is the conversion of forest to agricultural lands as well as collection of firewood for subsistence usage and for sale in urban centers (Thompson-Handler et al. 1995). Profits from agricultural products traditionally harvested in semi-rural areas and sold in markets in urban centers have plummeted due to the deterioration of the economy, roads, and the river transport system associated with the political instability (Dupain et al. 2000). While this may temporarily mitigate habitat destruction due to agriculture, the resulting trend is re-immigration of local people into the forests and subsequent establishment of semi-permanent settlements. In these establishments, people practice small-scale cultivation and subsistence hunting as well as collection of wood for fuel and shelter (Dupain et al. 2000; Reinartz & Bila Isia 2001). While some areas have protected status, this is merely a label that has no meaning; a total lack of laws and enforcement creates a climate in which people can live within the boundaries of the park and use the natural resources without consequences (Coxe et al. 2000).

Potential Solutions

Logging threats may be temporarily mitigated, though, because of the political instability and warfare that have plagued DRC for almost a decade. Logging companies have ceased their activities because of the dangers of working in a combat zone and as a result, habitat loss due to the extraction of trees and the infrastructure associated with unsustainable forestry techniques has ceased (Dupain et al. 2000). It is important, though, that when lands slated for logging become available in the future, that bonobo-friendly forestry techniques are used. That is, low impact, sustainable logging should be the goal of the Congolese government, especially if timber is to be the most important export commodity and the basis of its economic viability.

With only two reserves (Salonga National Park and Luo River Scientific Reserve) where bonobos occur and logging is prohibited, an important goal for the future is to create more protected areas as well as increase protection of bonobos both in and outside existing reserves (Reinartz & Bila Isia 2001).

Unfortunately, little can be done to alleviate the impacts of habitat loss due to subsistence agriculture and fuelwood collection at this time. Many Congolese have been displaced and have no other economic or even subsistence opportunities, and until there is stability in DRC, most research has ceased and bonobo populations cannot be reliably protected (Coxe et al. 2000).

Threat: Invasive Alien Species

There are a number of pathogenic and parasitic diseases that affect bonobos in the wild. Respiratory, gastrointestinal, cutaneous, or systemic bacterial infections can range in severity from latency to death (Whittier et al. 2001). Salmonella, Steptococcus, and Staphylococcus are common agents that can be found within the environment or can be transferred between humans and bonobos (Whittier et al. 2001). Other infectious agents that affect bonobos include viruses (poliovirus, measles, herpes, hepatitis, Ebola, etc.), fungal infections (ringworm), and parasites, both ectoparasitic and endoparasitic (Giardia, Cryptosporidium, Schistosoma, Strongyloides, etc.) (Whittier et al. 2001). While there may be some natural background rate of these diseases, certainly epidemics of some could threaten entire populations of bonobos. Unnatural exposure to these and other diseases could lead to rapid extinction in non-immune bonobos or very small populations of bonobos. As humans and bonobos come into close contact because of population growth, habituation to researchers, and hunting, the probability of disease transmission between species increases (Butynski 2001).

Potential Solutions

At research sites, precautions should be taken to ensure minimal exposure. This includes screening researchers and visitors, updating vaccinations (where applicable), limiting contact, and burying human waste (Whittier et al. 2001). Health education about zoonotic diseases in local communities may also decrease the incidence of disease transfer between bonobos and humans.

Threat: Harvesting (hunting/gathering)

As the population explodes in Central Africa, traditional values are eroded as are time-honored tribal customs. This is important in the case of the bonobo because across many tribes in DRC, it has been traditionally taboo to hunt these apes, though that sentiment is quickly falling by the wayside (Thompson-Handler et al. 1995; Coxe et al. 2000). With no other economic opportunities, local people must trade bushmeat for clothes, medicines, soap, spices, and other necessities as well as use it as a primary protein source (Dupain & Van Elsacker 2001). Moreover, with an active zone of military occupation bisecting the bonobo’s range, troops and displaced people consume bushmeat as a main source of protein and rely on its sale as a source of income (Reinartz & Bila Isia 2001).

The role of lumber companies in the bushmeat market cannot be underestimated. They provide guns and ammunition, transportation to and from the forests where bonobos are hunted, boats to move carcasses between the forest and urban centers, and workers hunt, sell, and eat the meat (Butynski 2001; Dupain & Elsacker 2001). Guns have also become quite prolific and readily available as the civil war erupted (Coxe et al. 2000).

Infant bonobos are also highly prized as pets, and as adult bonobos are killed for meat, infants are sold in markets in urban centers such as Kinshasa. It is estimated that between five and 10 adults are killed to capture one infant, as reproductive-aged adults are culled from the population, the reproductive capacity of the population will dwindle (Reinartz & Bila Isia 2001).

Potential Solutions

Foreign logging companies must be held accountable for their roles in the bushmeat trade. Instead of facilitating the illegal hunting, transportation, sale, and consumption of bonobos, logging companies should provide alternate food sources for their employees and prohibit the transportation of meat and hunting paraphenelia on company boats (Dupain & Van Elsacker 2001).

Local communities that depend on bonobo meat for protein and as currency to obtain necessary supplies should be provisioned with alternate food sources and sundries by international aid organizations. Giving people alternatives may alleviate some of the pressure on bonobo populations in the most heavily hunted areas. Providing other economic opportunities is another crucial factor in decreasing reliance on bushmeat. In times of peace, this can be achieved by maintaining a strong research presence in areas that have been traditionally used as hunting grounds (Dupain & Van Elsacker 2001). Researchers can often provide jobs to local people as field assistants, educators, and camp staff. They not only offer paid work, but having locals involved in research and bonobo conservation creates a meaningful connection between people and wildlife that may influence their future actions (Wrangham 2001).

Educating potential buyers of infant bonobos in the markets of Congolese urban centers is another way to decrease the market for apes as pets.

Threat: Accidental Mortality

Occasionally bonobos are ensnared in traps set for other terrestrial mammals and are injured (Kano 1992; Coxe et al. 2000). There is little data on the scope of this problem.

Threat: Persecution

Traditionally, bonobos were revered and viewed as relatives to local people (Coxe et al. 2000). Where they are not habituated, bonobos are extremely shy and afraid of people (de Waal 1996). Except for where they are hunted as food, there are no instances of human-bonobo conflict.

Threat: Changes in Native Species Dynamics

Bonobos have no known predators and as such their population size and structure is not affected by predator-prey interactions (de Waal 1996).

At Wamba, there have been high instances of physical handicaps noted in the study groups. Missing digits and limbs dominate those deformities recorded, and there is some speculation that leprosy could be one of the causes of these abnormalities (Kano 1992).

Potential Solutions

Limiting physical contact between bonobos and humans is crucial to minimizing transfer of all diseases. In instances where it is appropriate and the bonobos are habituated, veterinary care may also be helpful.

Threat: Intrinsic Factors

Bonobos are long-lived and mature slowly, producing few offspring over their lifetimes, as such population growth rates are inherently slow. Because of these qualities, disturbances can have significant affects on overall population size (Thompson-Handler et al. 1995). Any demographic changes are compounded by the effects of habitat fragmentation, range restriction, and decreasing population sizes. For example, when two populations that used to come into contact are separated by an impassable barrier, such as a logging road, gene flow between the two communities ceases and problems such as inbreeding depression and subsequent fixation of deleterious alleles (Thompson-Handler et al. 1995; Coxe et al. 2000).

Potential Solutions

Efforts to decrease habitat fragmentation should be of greatest importance. Demographic changes should be minimized, if at all possible, by decreasing the demand for bushmeat as well as setting up orphanages and refuges for infant bonobos confiscated in markets.

Captive breeding programs are also important and may serve as “arks” for bonobos. It should continue to be the goal of programs to produce and maintain viable populations ex situ.

Threat: Human Disturbance

Political instability has had deleterious effects on all life in DRC and continues to impede bonobo conservation and research efforts. All research has been abandoned in this area, and few reports of bonobo populations at the most important study sites are available. In some cases, those local people involved in the research have managed to stay and serve as guards, though they are unable to receive any salaries from researchers and communication is impossible. Where bonobos have been habituated, their risk of being shot by soldiers and hunters is great, and research assistants have little means to protect these apes from such persecution (Coxe et al. 2000).

Potential Solutions

There are few options as long as the area remains insecure for both foreign and domestic assistance and involvement (Coxe et al. 2000).

LINKS TO MORE ABOUT CONSERVATION

CONSERVATION INFORMATION

• African Great Apes  (WWF African Great Apes Programme, January 2005)
• Best Practice Guidelines for the Re-introduction of Great Apes  (IUCN/SSC Primate Specialist Group)
• Slaughter of the Apes  (October 13, 2006)
• The Bonobo Conservation Inititative
• Links for all species

CONSERVATION NEWS

• Why are We Eating Bonobos? Can We Save Africa’s Vast Wildernesses from Destruction?  (National Geographic; October 14, 2012)
• Conservationist devotes life to bonobos  (Marion Star; December 5, 2010)
• Going Ape in Central Africa: Meeting Our Closest Cousins in the Near-Wild Within Easy Reach of Major Cities  (Huffington Post; October 12, 2010)
• Into the Congo: saving bonobos means aiding left-behind communities, an interview with Gay Reinartz  (Mongabay; September 23, 2010)
• Bonobos going wild  (Charlotte Observer; July 6, 2009)
• Reintroducing Bonobo Apes Into The Wild: Researchers To Monitor Progress  (ScienceDaily; June 15, 2009)
• New rainforest reserve in Congo benefits bonobos and locals  (Mongabay; May 25, 2009)
• Massive New Rainforest Reserve Established in the Democratic Republic of Congo  (Yubanet; November 16, 2007)
• Best Practice Guidelines for the Re-introduction of Great Apes  (IUCN/SSC Primate Specialist Group)
• ‘Protected’ Congo forest is logged regardless  (New Scientist; April 11, 2007)
• Illegal Loggers Mutilating Congolese Forests  (Environment News Service; February 28, 2007)
• Trust’s donations save apes worldwide  (Des Moines Register; December 15, 2006)
• Monkey business  (Carte Blanche; October 29, 2006)
• Great Ape Trust Awards $22,000 in Conservation Grants  (E-Wire; August 22, 2006)
• Bush-meat traders threaten Nigeria’s chimps  (Georgia Straight, Canada; November 3, 2005)
• Woods Hole Research Center scientist part of international initiatives to save the great apes  (EurekAlert; October 11, 2005)
• New Conservation Groups Formed at World Wilderness Congress  (Environment News Service; October 10, 2005)
• Conservationists seek to protect apes  (Associated Press; July 27, 2005)
• Expert highlights mobile phone threat to great apes  (Australian Broadcasting Company; March 10, 2005)
• Study links Ebola outbreaks to animal carcasses  (EurekAlert; February 14, 2005)
• Pygmy chimpanzees on the brink of extinction  (Independent Online, South Africa; January 10, 2005)
• Fences ‘can help apes’ survival’  (BBC News; May 5, 2004)
• African apes being eaten into extinction  (Sunday Herald, UK; October 11, 2003)
• African `bushmeat’ trade raises health, conservation fears  (Taipei Times; August 25, 2003)
• Balancing Wildlife Conservation with Human Survival  (Inter Press Service News Agency; October 11, 2003)
• Bonobos’ threat: hungry humans  (Christian Science Monitor; June 7, 2001)
• Dire Outlook for Many Primates  (BBC; May 12, 2000)
• Eating apes imperils species, spreads AIDS  (ABC Science Online, Australia; September 15, 2003)
• Great apes in peril  (BBC News; May 20, 2001)
• Growing demand for ‘bushmeat’ threatens great apes  (CNN; August 11, 1999)
• Last chance to save great apes from extinction  (Guardian Unlimited; May 21, 2001)
• Links for all species

ORGANIZATIONS INVOLVED IN Pan paniscus CONSERVATION

• Bonobo Conservation Initiative
• Jane Goodall Institute France
• Paniscus
• Projet Protection des Gorilles

Content last modified: December 1, 2010

Written by Kristina Cawthon Lang. Reviewed by Frans de Waal.

Cite this page as:
Cawthon Lang KA. 2010 December 1. Primate Factsheets: Bonobo (Pan paniscus) Conservation . <http://pin.primate.wisc.edu/factsheets/entry/bonobo/cons>. Accessed 2020 July 29.

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IMAGES

	Pan paniscus Photo: Joris Jacobs
	Pan paniscus Photo: Joris Jacobs
	Pan paniscus Photo: Joris Jacobs
	Pan paniscus Photo: Joris Jacobs
	Pan paniscus Photo: Joris Jacobs
	Pan paniscus Photo: Joris Jacobs
	Pan paniscus Photo: Joris Jacobs
	Pan paniscus Photo: Joris Jacobs
	Pan paniscus Photo: Joris Jacobs
	Pan paniscus Photo: Max Planck Institut
	Pan paniscus Photo: Max Planck Institut
	Pan paniscus Photo: Max Planck Institut
	Pan paniscus Photo: Max Planck Institut
	Pan paniscus Photo: Max Planck Institut
	Pan paniscus Photo: Max Planck Institut
	Pan paniscus Photo: Max Planck Institut
	Pan paniscus Photo: Max Planck Institut
	Pan paniscus Photo: Max Planck Institut
	Pan paniscus Photo: Max Planck Institut
	Pan paniscus Photo: Max Planck Institut
	Pan paniscus Photo: Max Planck Institut
	Pan paniscus Photo: Max Planck Institut
	Pan paniscus Photo: Primates in Art & Illustration Collection