Animal Info - Bonobo
(Other Names: Chimpancé Pigmeo, Chimpanzé Nain, Chimpanzé
Pygmée, Dwarf Chimpanzee, Gracile Chimpanzee, Mokomboso, Pygmy Chimpanzee, Zwergschimpanse)
Pan paniscus
Contents
1. Profile (Picture)
2. Tidbits
3. Status and Trends (IUCN Status, Countries Where
Currently Found, Taxonomy, Population Estimates, History of Distribution, Threats and Reasons
for Decline)
4. Data on Biology and Ecology (Size
and Weight, Habitat, Age to Maturity, Gestation
Period, Birth Season, Birth Rate, Early Development, Dispersal, Maximum Reproductive Age, Maximum Age, Diet, Behavior (Activity
Patterns, Locomotion, Living
in Trees, Sleeping, Intelligence),
Social
Organization (Group Structure and
Composition, Inter-group Relations, Relations
between Individuals), Age and Gender Distribution, Density and Range)
5. References
Profile
Pictures: Bonobo
#1 (18 Kb JPEG); Bonobo
#2 (21 Kb JPEG);
Bonobo #3 (40 Kb JPEG) (Arkive)
The bonobo is covered by black fur, which may turn to a grayish color in aged
individuals. It has a black face and black ears. A white "tail-tuft" commonly remains in
adults. Males are about 78 cm (31") tall and females are about 73 cm
(29") tall. In most of its range, the bonobo occupies three kinds of
forest: swamp
forest, primary forest, and secondary forest resulting from clear-cutting. Fruits form the bulk of the bonobo's diet,
but other plant parts, fungi, eggs, and invertebrates
are also eaten. Bonobos have been observed to eat small mammals but have rarely been observed to actively hunt for meat.
The bonobo is diurnal,
arboreal, and terrestrial.
It is generally active from dawn to dusk. Bonobos sleep in trees and do most of
their feeding in trees, although they also forage on the forest floor.
Preparation for sleeping involves the construction of a flimsy day-nest and a
sturdier night-nest. Sleeping nests are typically built in
trees at 20 m (66') above the ground. Although the bonobo spends much of its
time in the trees, eating and sleeping, it travels mostly on the ground.
The bonobo has a
"fission-fusion" social organization which is
gregarious and
generally mutually tolerant. Individuals belong to groups called
"communities." While foraging and traveling, the community members generally
break up into subgroups, called "parties." When parties from
different communities meet each other, sometimes they are peaceful. At other times, there may be loud
vocalizing, agonistic displays, and, occasionally, serious fighting.
Social relations within bonobo communities are significantly
affected by the species’ sexual behavior. Bonobos use sex to appease, to promote the sharing of
food, to make up after fights, to gain favors, and generally to strengthen
relationships. Sexual encounters are strikingly casual,
almost more affectionate than erotic.
Female associations seem to form the primary basis of
the community, and it is the females that generally have the leadership role. If there is a female rank order, it is largely based on seniority rather
than physical intimidation - older females generally have a higher status than
younger ones. Dominant status among males is actively sought, and this leads
to more fighting among males than among females. On the
other hand, male bonobos also groom each other regularly. Adult females are dominant over males. Females sometimes form coalitions
against males and can influence the males to behave submissively. Males are only rarely aggressive towards
females.
The bonobo has only been found in The Democratic Republic of
the Congo. Within its range, the bonobo is absent or rare
in many areas and is common only in a few scattered localities. Threats to the bonobo
include loss and fragmentation of habitat due to
increasing human population, agricultural expansion and logging. It also is
hunted extensively by people for meat and for body parts used in religious
rituals and traditional medicine.
Tidbits
*** The bonobo is also called a "pygmy chimpanzee," but this is a
misnomer. The bonobo has a more slender build than chimpanzees, but it weighs as
much as one of the subspecies of
chimpanzee. (Macdonald
2001)
*** The bonobo has the only great ape families led by females. It has a
sophisticated social structure that encourages cooperation and peace and settles
disputes through sex. Bonobos coexist peacefully in large communities of over 100
members. (Focus 2005b)
*** The origin of the name "bonobo": In 1936, the German Zoo
Director H. Heck bought two pygmy chimpanzees (as they were known at the time)
from an African animal dealer. The dealer called them "bonobos". The
origin of this term is unclear - some think that it may be a garbled version of
"Bolobo", a town in The Democratic Republic of
the Congo where scientists first found bonobos in the 1920's. Heck
then coined this word as a German species name. (Kemf
& Wilson 1997, Kortlandt 1998)
*** Etymology of the scientific name
of the bonobo: the genus name
("Pan") comes from the name of the Greek god of flocks, shepherds,
and woods, who had a human torso, but the legs, beard, ears, and horns of a
goat; the species name ("paniscus")
is a diminutive (originating from when the bonobo was originally (and erroneously - see
above) known as the "pygmy chimpanzee") (de
Waal 1997).
*** Although they are fundamentally similar in anatomy, there are a number of
characteristics that can be used to distinguish the bonobo from the chimpanzee.
The bonobo has a black face (the chimpanzee’s face is variable from pink to
brown or black), a prominent white
tail tuft which is retained by adults (chimpanzees only have one at the juvenile
stage), and a slimmer body and relatively longer legs. Behavioral
differences between the bonobo and the chimpanzee include: bonobos are
sensitive, lively and nervous, whereas chimpanzees are coarse and hot-tempered;
and physical
violence almost never occurs in bonobos, yet is common in chimpanzees. From the
standpoint of their social organizations, both bonobos and chimpanzees live in fission-fusion
societies, but otherwise there are major differences. For example, chimpanzee
males are more dominance-oriented and "political" than bonobo males,
and chimpanzee females have less social influence than their bonobo
counterparts. Furthermore, bonobos rarely perform the complex confrontations known
among chimpanzees, in which one opponent recruits supporters against the other,
thus forcing the latter to do the same, until entire sections of society oppose
each other on the battle field. (de
Waal 1997, Burnie
& Wilson 2001, Macdonald 2001,
WWF 2005)
*** The Bonobo and People:
- Most of the scientific community now consider bonobos and chimpanzees
to be humans' closest living relatives. Genetic evidence indicates that we
last shared a common ancestor with them about 6 million years ago. (Macdonald
2001)
- According to DNA analyses, humans share over 98 % of our genetic material
with both the bonobo and the chimpanzee (de
Waal 1997).
Status and Trends
- 1960's: Insufficiently Known
- 1970's - 1994: Vulnerable
- 1996: Endangered
- 2000 - 2004: Endangered (Criteria:
A2cd) (IUCN
2004)
Countries Where the Bonobo Is Currently Found:
2004: Occurs in The Democratic Republic of
the Congo. (IUCN
2004)
In 1929 it was first suggested by some scientists that the anatomical
differences between the bonobo and the chimpanzee were sufficient to warrant
their classification as separate species.
The bonobo was still considered by others to be a subspecies
of chimpanzee. However, recent evidence suggests that the two are distinct species.
(de
Waal 1997, Nowak
1999).
Population Estimates:
[Note: Figures given are for wild populations only.]
There are no reliable estimates of total numbers for the bonobo. Many years
of civil unrest in The Democratic Republic of
the Congo has meant that few recent surveys have been done. Distribution of
bonobos within the country is very patchy, and total population estimates vary
widely (from 10,000 to 50,000), reflecting our poor understanding of this ape. (WWF 2005)
History of Distribution:
The bonobo has only been found in one region of Central Africa:
between the Zaire River, the Lomami River, the Kasai/Sankuru Rivers, and the
Lake Tumba/Lac Ndombe region in The Democratic Republic of
the Congo. It appears to be absent from the central part of this area
between the Momboyo River and the Busira River. Within this large forest zone,
totaling approximately 350,000 sq km (135,000 sq mi), the bonobo is absent or rare
in many areas and is common only in a few scattered localities. (de
Waal 1997, WWF 2005)
Distribution
Map #1 (14 Kb GIF) (Afr.
Mamm. Databank)
Distribution
Map #2 (25 Kb GIF) (Calvin
2005)
Threats and Reasons for Decline:
The bonobo is threatened by loss and fragmentation of habitat due to
increasing human population, agricultural expansion and logging. It also is
hunted extensively by people for meat and for body parts used in religious
rituals and traditional medicine. Trapping by snares set for other animals is an
additional threat. (Nowak
1999, Macdonald 2001)
Data on Biology and Ecology
Height: Male: 73 - 83 cm (29 - 33"); Female: 70 - 76 cm (28 -
30") (Macdonald 2001).
Weight: A survey of most of the world's captive bonobos in
the 1990's put the average weight of males at 43 kg (95 lb) and the
average weight of females at 37 kg (82 lb) (de
Waal 1997).
Habitat:
In most of its range, the bonobo occupies three kinds of forest: 1) Swamp
forest near the rivers includes relatively low trees, which are supported by
prop roots, or by leaning against each other, because of the loose, muddy
soil. 2) Primary forest grows on a firmer foundation and is darker because of the
dense canopy and the much taller trees, including trees up to 50 m (160')
high. The lack of light makes for relatively sparse undergrowth. 3) Finally,
there is the secondary forest resulting from clear-cutting. After the loggers have left the area, vegetation soon covers their traces, but even when
full-sized trees have returned, tree density remains below that of the primary
forest. Thick patches of herbs grow at places where sunlight reaches the
forest floor. In some parts of their range, the bonobo habitat alternates
between forest, open woodlands, and grasslands. (de
Waal 1997)
The bonobo is found in the Southern Congo Basin Forests and Western Congo Basin Forests
Global 200 Ecoregions. (Olson & Dinerstein 1998, Olson & Dinerstein 1999)
Age to Maturity:
Females reach
sexual maturity at approximately 12 years of age and the first birth
occurs at 13 - 15 years of age. A female bonobo reaches adult size at 14 - 16 years of age.
(de
Waal 1997, WWF 2005) The male bonobo reaches its full adult size at about 16
years of age, but it may be sexually mature well before this (Macdonald 2001).
The gestation period is 220 - 240
days.
Birth Season:
No seasonality in the bonobo's reproduction has been observed (Nowak
1999).
Birth Rate:
In the wild, there are single births about every 5 years (de
Waal 1997). Females have between five and six offspring in a lifetime (WWF 2005).
Early Development:
After a period of clinging to its mother’s belly, an older infant rides
on her back. Its mother takes it everywhere she goes. Even after 1 year of
age, a bonobo infant does not walk or climb much, and it is very slow. The
mother keeps it nearby. A young bonobo starts to play with others at about 1.5
years of age. The mother carries her youngster while traveling until it
reaches at least 3 or 4 years of age. (de
Waal 1997, Colbeck
1998)
A young bonobo is weaned at about 3
years of age. The mother continues to protect, groom, and share nests with her
offspring for another year or two after weaning.
A female juveniles gradually loosens her tie with her mother and travels
farther away from her than does a son. Sometimes a young female is observed
who stays alone, or is peripheral to a party, even if she is only 5 or 6 years
of age. A son, however, is always near his mother. (de
Waal 1997, Burnie
& Wilson 2001)
An adolescent female bonobo disperses from her natal
community before she has started to reproduce, generally at the age of 7, and
joins a neighboring community. She has no further ties with her mother. Adult
females occasionally transfer into another community, although this
apparently is rare. A male stays in his mother’s community for life and
maintains a permanent association with her. (de
Waal 1997, Nowak
1999, Macdonald 2001, WWF 2005)
Maximum Reproductive Age:
Estimated at 40 years (de
Waal 1997).
Maximum Age:
A captive female bonobo was estimated to be around 40 years old (de
Waal 1997). The lifespan of bonobos in the wild is unknown (WWF 2005).
Diet:
Fruits form the bulk of the bonobo's diet, but leaves, pith, flowers, bark,
seeds, honey, fungi, eggs, and invertebrates
(e.g. termites, caterpillars and earthworms) are also eaten. The bonobo has
been observed to eat small mammals, including shrews, flying squirrels, and
small antelopes such as young duikers. However, unlike the chimpanzee, the
bonobo has rarely been observed to actively hunt for meat. It captures most
animal prey individually and opportunistically, rather than during a group
hunt. The bonobo does most of its feeding in trees, mostly in the crowns of
large fruit trees, although it also forages on the forest floor. The main
feeding activity, in the morning, is usually concentrated on fruits. In the
afternoon the bonobo may switch to less energy-rich, more fibrous foods. (de
Waal 1997, Kingdon 1997, Nowak
1999, Macdonald 2001, Burnie
& Wilson 2001, WWF 2005)
Behavior:
Activity Patterns: The bonobo is diurnal,
arboreal, and terrestrial.
It is generally active from dawn to dusk, a 12 - 13 hour period in its
equatorial habitat. It feeds for at least half of this time unless food is
plentiful, whereupon it may feed for only a third of the time. The bonobo
begins feeding in a tree, frequently in the dense upper forest canopy,
shortly after waking, rests, moves leisurely on the ground to the next food
tree, becomes less active toward the middle of the day, and then repeats the
pattern in the afternoon. Average daily movement is about 2.4 km (1.5 mi). (de
Waal 1997, Kingdon 1997, Nowak
1999, Macdonald 2001)
Locomotion: The bonobo travels mostly on the
ground, where it engages in quadrupedal
"knuckle-walking," a form of locomotion it shares with the gorilla.
The bonobo can stand upright and often does so when climbing or reaching for
food, but its bipedal locomotion is
awkward compared to our own. The bonobo, like other apes, does not swim (Therefore,
wide rivers such as the Zaire River are barriers to the mixing of populations
of apes on either side of the river.). However, the bonobo shows no hesitation in
wading through shallow water. (Stuart & Stuart 1996,
de
Waal 1997. Macdonald 2001)
Living in Trees: The bonobo has a
body that is well adapted for arboreal
activities. Its arms are considerably longer than its legs, its fingers much
longer than those of humans, and its shoulder joints are highly mobile. These
and other features of its skeleton and musculature enable it to hang from
tree branches by its arms and make it adept at climbing tree trunks and
lianas and at clambering in the crowns of trees. (Macdonald 2001)
Sleeping: The bonobo sleeps in a tree. Preparation for sleeping involves the construction of
a flimsy day-nest and a sturdier night-nest. Nests are commonly made close to the current feeding
site, and the bonobo prefers to seek out flexible, multi-branched trees for
this purpose. It draws in all reachable fronds and stuffs them into a wedging
fork to form a springy, globular platform. Sleeping nests are typically built in
trees at 20 m (66') above the ground. One study reported that the
average height of 46 nests seen was 25 m (82‘). (MacKinnon 1976, Lee
et al. 1988, Kingdon 1997, Macdonald 2001)
Intelligence: The bonobo has a brain
that, with a volume of 300 - 400 cc (18 - 24 cu in), is large both in absolute terms
as well as relative to its body size. It does well on problem-solving tasks in laboratory
settings, and it has shown some capability to engage in symbolic communication
in captivity when given intensive training. Tool use in the wild has not been
observed, but captives have been reported to construct ropes to swing from; to
wipe themselves with leaves; and to use sticks to probe, rake, and pole-vault
over water. (Nowak
1999, Macdonald 2001)
Social Organization:
Group structure and
Composition: The bonobo has a
"fission-fusion" social organization which is
gregarious and
generally mutually tolerant. Individuals belong to groups called
"communities" that have 15 - 150 members and that seem to be
socially bonded. While foraging and traveling, the community members generally
break up into subgroups, called "parties," that vary in size and
composition on a daily and even hourly basis. All associations, except the one
between mother and dependent offspring, are of a temporary nature. Party size depends on the availability of food - parties grow
larger if individuals can feed together, such as in large fruiting trees.
Parties usually contain 2 - 15 individuals but may contain as many as 40. A
party is usually based on a female and her male offspring plus adult female
associations. Community members tend to gather at night ("fuse") in
clusters of nests. In the morning, they break up again ("fission")
into foraging parties. (de
Waal 1997, Nowak
1999, Macdonald 2001, WWF 2005)
Inter-group Relations: There is extensive overlap
among community home ranges, but parties of one community avoid those of the other. When there is
an encounter, sometimes they are peaceful. At other times, there may be loud
vocalizing, agonistic displays, and occasionally serious fighting. But the
boundary patrols and deliberate "lethal raids" of the chimpanzee
have not been observed. (Nowak
1999, Macdonald 2001)
Relations between Individuals: Adult females appear to have a tendency
to come together in strongly bonded units, even though they usually are not
close relatives. Such female associations seem to form the primary basis of
the community, and it is the females that generally have the leadership role.
A status hierarchy among females is not wholly absent, but it is very vague - there are no "high-ranking" females, only "influential"
ones. If there is a female rank order, it is largely based on seniority rather
than physical intimidation - older females generally have a higher status than
younger ones.
Dominant status among males is actively sought, and this leads to more fighting among males than among females. On the
other hand, male bonobos also groom each other regularly. Females support their adult sons in
competition with other males and can influence their sons’ dominance
ranking. A
high-ranking mother confers high-ranking status on her male offspring. Whereas rank
positions near the top, especially the position of alpha
male, tend to be
quite clear, mid-ranking and lower positions are not so well defined.
Adult females are dominant over males. Females sometimes form coalitions
against males and can influence the males to behave submissively. Furthermore,
males commonly defer to females during feeding, rather than trying to take
feeding spots or food items. Males are only rarely aggressive towards
females. Even younger females sometimes dominate adult males.
Social relations within bonobo communities are significantly
affected by the species’ sexual behavior, which is used to manage and
diffuse tension. When it comes to bonobo sex, no rules apply - everybody does
it with everybody else. Bonobos use sex to appease, to promote the sharing of
food, to make up after fights, to gain favors, and generally to strengthen
relationships. Sexual encounters are strikingly casual,
almost more affectionate than erotic.
(de
Waal 1997, Colbeck
1998, Nowak
1999, Macdonald 2001, WWF 2005)
Age and Gender Distribution:
The total numbers of identified individuals in the best-known wild bonobo
communities, together with the ratios of adult males to adult females, have
been reported as follows (de
Waal 1997):
- Lomako Eyengo: 34, 6:12
- Lomako Hedons: 44, 8:14
- Lomako Rangers: 26, 5:8
- Wamba E: 75, 20:20
- Wamba E1: 32, 7:9
- Wamba E2: 36, 8:11
Density and Range:
Density
Estimates of bonobo density in The Democratic Republic of
the Congo include (van
Krunkelsven et al. 2000, Oryx 2001):
- Lilunga: 0.43 bonobos/sq km (1.1
bonobos/sq mi)
- Lomako
Forest: 2.98 bonobos/sq km (7.75 bonobos/sq mi)
- Salonga National Park: 1.15 bonobos/sq
km (3.0 bonobos/sq mi)
- Wamba: 1.7 bonobos/sq km
(4.4 bonobos/sq mi)
- Yalosidi: 0.45
bonobos/sq km (1.2 bonobos/sq mi)
Generally a home range of bonobos
has a density of approximately 2 bonobos/sq km (5
bonobos/sq mi) (Nowak
1999).
Range
Bonobo communities occupy home ranges
of about
22 - 68 sq km (8.5 - 26 sq mi) (Nowak
1999).
References
Afr. Mamm. Databank,
Arkive, Badrian & Badrian 1977,
Burnie & Wilson 2001, Calvin
2005, Colbeck
1998, Cologne Zoo, Focus
2005b, IUCN
1966, IUCN 1994, IUCN
1996, IUCN 2000, Kemf
& Wilson 1997, Kingdon 1997, Kortlandt
1996, Kortlandt 1998, van
Krunkelsven et al. 2000, Lee
et al. 1988, Macdonald 2001, MacKinnon 1976, Nowak
1999, Oates 1996, Olson & Dinerstein 1998, Olson & Dinerstein 1999, Oryx
2001, Rowe
1996, Stuart & Stuart 1996,
Susman et al. 1981, de
Waal 1997. WWF 2005
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