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Chimpanzee tool use for honey and termite extraction in Central Africa.

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American Journal of Primatology 34309-317 (1994)
Chimpanzee Tool Use for Honey and Termite Extraction
in Central Africa
Washington University, St. Louis, Missouri; 'Yule University, New Haven, Connecticut
Observations are presented primarily from two study sites located in the
extreme southwestern tip of the Central African Republic. The use of
flexible stalks and rigid sticks to extract termites from mounds and pounding, prying, and digging tools to penetrate melipone, honey bee, and
ground-dwelling bee hives by Pan t. troglodytes are documented or inferred
from circumstantial evidence. Functionally, termite extraction tools were
similar to other locations in west and central Africa, but the plant species
used were considerably different. Extraction of bees using large pieces of
wood a s pounding tools has not been recorded elsewhere in wild chimpanzees. No environmental factor that differs between the east and west of the
range of P. t. troglodytes that would cause the difference in tool use was
identified. o 1994 Wiley-Liss, Inc.
Key words: Pun t. troglodytes, chimpanzee, tools, bees, termites, Central
African Republic
The use of tools by wild chimpanzees (Pan troglodytes) is well known, with
several recent reports in the literature [Collins & McGrew, 1987; Hannah & McGrew, 1987; Sugiyama et al., 1988; Yamagiwa e t al., 1988; Bermejo et al., 1989;
Brewer & McGrew, 1990; Boesch & Boesch, 19901. Most of these reports are derived from studies of chimpanzees in west and east Africa with relatively few data
for the central-west African subspecies of chimpanzee (Pan t. troglodytes). Termitefishing behavior using thin and tensile stalks for fishing and rigid sticks for perforating mounds has been reported for this subspecies [Jones & Sabater-Pi, 1969;
Sabater-Pi, 1974; McGrew & Rogers, 1983; Sugiyama, 1985; Muroyama 19911. The
use of sticks to obtain honey from a ground bee hive has also been reported for this
subspecies [Merfield & Miller, 19561.
In this paper we discuss various uses of tools by chimpanzees in the Central
African Republic and the Republic of Congo, the eastern range of P. t. troglodytes.
We document the use of both flexible stalks and rigid brush sticks to extract
termites from mounds by P. t. troglodytes. We also report on pounding and prying
tools used to break and open melipone bee (Trigona sp.) and honey bee (Apis
Received for publication August 1, 1992;revision accepted January 31, 1994.
J. Michael Fay's present address is NYZSiThe Wildlife Conservation Society, Bronx, NY 10460.Address
reprint requests there.
0 1994 Wiley-Liss, Inc.
310 / Fay and Carroll
melifera) hives, and digging tools used to extract ground dwelling bees (Trigona
sp.) by P. t. troglodytes.
Data are presented primarily from two study sites located in the extreme
southwestern tip of the Central African Republic in the Dzanga-Sangha region,
east of the Sangha River, a large western tributary of the Congo River. Site 1
(Ndakan, study area of J.M.F.) is located on the Sangha River just north of the
border with Congo (2"20'N,16"10'E). Site 2 (Bai Hokou, study area of R.W.C.) is
located 25 km east by southeast of the town of Bayanga (2"51'N,16"28'). Both study
sites are in the semi-deciduous forest zone with Raphia spp. swamp forest along the
minor rivers, Guibourtia demeusii flooded forest along the Sangha River, and
Gilbertiodendron dewevrei forest along upland watercourses. The semi-deciduous
forest is dominated by Entandrophragma spp., Polyalthia suaveolens, Albizia spp.,
Triplochiton scleroxylon, Combretodendron macrocarpum, Celtis spp., Diospyros
spp., Irvingia spp., Eribroma oblonga, Klainedoxa gabonensis, Terminalia superba,
Gambeya spp., Autranella congolensis, Piptadeniastrum africanum, Strombosia
sp., Funtumia elastica, Dialium zenkeri, Pterocarpus soyauxii, and Erythrophleum
suaveolens. The forest surrounding the northern study area was selectively logged
from 1972 to 1987.
Additional notes are included from two sites in the Republic of Congo, one 90
km E of Bai Hokou (2"50'N, 17'20'E) and the other along the Gabon border in a
forest 60 km N of the town of Mbomo (0"55'N, 14"35'E).
The data presented below include ad libitum observations a t chimpanzee encounters, dung analysis, and circumstantial evidence at feeding sites. Discussions
with Bayaka (Pygmy) trackers are also noted.
Southern Site (Ndakan, J.M.F. Observations)
Termite-tunnelprobing stalks. On 19 February 1988 a n adult chimpanzee
of unknown sex was observed a t the base of a large termite mound (Macrotermes
sp.). The chimpanzee was 15 m away, with only its head visible through the vegetation. The individual, observed for several seconds before it fled, held a stick
broadside between its lips. At the mound a 35.5 cm long piece of Ataenidia conferta
(Marantaceae)petiole (Fay 8245, MO), 4 mm in diameter was found on the ground.
One end was frayed and brushlike to 30 mm with a very sticky texture. This was
assumed to be due to the chimpanzee's mucus, but it seemed more viscous than
human mucus. There were several very small, white termite workers adhering to
the mucous coating. No large worker termites were present on the petiole. The
other end of the tool was oblique and appeared to have been cut off with the teeth.
Close inspection around the circumference of the mound revealed two small
circular holes, ca. 8 mm diameter, 15 cm apart, with smooth edges. The tool was
inserted in one of the holes and thrust back and forth several times without extracting it. It entered the hole its entire length without resistance and upon removal the brush end of the tool was covered with termite soldiers and workers. The
tool was inserted a second time, in the other hole and upon removal the tool held
12 soldier and large worker termites and many small white workers. The soldiers
and large workers were biting the brush end of the tool and the small workers
simply adhered to the mucus.
Examination of the two small holes in the mound showed that the surrounding
matrix had been recently broken to about 5 cm around each hole. In both cases
termites had rebuilt the mound damage. The breaks must have occurred 1-2 days
Chimpanzee Tool Use / 311
previously because the clay was already dry but somewhat plastic and a darker
shade than the surrounding matrix, indicating a higher moisture content. This
observation was made a t the height of the dry season when termite mounds in this
area, built of a very heavy-textured soil, are extremely hard. The holes were not
exit holes for alate termites because the observation was made in a non-swarming
period. It is not known if chimpanzees originally perforated the termite mound.
Several other likely termite digging sticks were found protruding from Macrotermes spp. mounds in the Ndakan area in 1988. On one occasion three sticks
were found protruding from the base of a mound, having been incorporated into
the mound matrix, and apparently left by chimpanzees. The sticks came from
Thomandersia laurifolia (Acanthaceae). They were ca. 25-35 cm long and usually
had a brush end. Bayaka note that A . conferta petioles are the preferred tool used
by chimpanzees when fishing for termites, and T. luurifolia for perforating
Pounding tools for melipone bees. On 12 May 1988 a regular booming
sound was heard a few hundred meters to the south of the observer (J.M.F.). The
sound was similar to a person chopping a tree with a n ax but lacked the metallic
ping. The sound persisted for 5-10 sec. Approximately 2 min later a second bout of
the booming was heard. Upon searching for the source of the sound it became
evident that it was emanating from a large (ca. 170 cm diam.) Autrunella congolensis tree 200 m from where the sound was initially heard. Upon approaching the
tree a large female chimpanzee was observed ca. 20 m up the trunk in the crotch
of a primary branch. The observer’s presence was not noticed by the chimpanzee
that was manipulating and consuming contents from a large melipone (Trigona
(Hypotrigona) gribodoi Mag.) [ex Bahuchet, 19851 hive attached to a very large
primary branch of the tree. These hives, constructed with copious amounts of
propolis, are often attached high on the main trunk or primary branches of several
of the largest emergent species of trees in the study area (e.g., Entandrophragma
utile, Ceiba pentandra, Autranella congolensis, Milicia excelsa).
The chimpanzee was standing bipedally, grasping the tree with its right hand
and manipulating and eating with its left hand. After some time i t stepped back on
the branch and picked up a large dead piece of branch 30-40 cm long and 10 cm
diameter which was lying in the crotch of the large primary branch. It then proceeded, with both hands and the right hand only, to use the wood to batter the bee
hive. The chimpanzee grasped the piece of wood in the middle and used the end for
a pounding surface. After hitting the hive ca. 10 times, the pounding tool was
placed back in the crotch of the branch and the same position was taken to extract
and consume honey and probably bee larvae. The chimpanzee was observed inserting the left index finger into the hive and then into its mouth several times. I t
repeated this cycle several more times, each time beating the hive 6-10 times,
intermittently swatting at bees around its eyes with a cusped fist and feeding.
After several minutes the chimpanzee spotted the observer, issued distress
screams and moved higher into the tree. At this point the observation was terminated. It was not established if the chimpanzee transported the dead branch up to
the perch or if i t was found in the tree.
On 29 May 1988, in the same area as the previous observation, booming was
again heard when J.M.F. was with Bayaka trackers. Without prompting or hesitation they described the origin of the sound which followed very closely the honey
extraction observation that J.M.F. had made two weeks earlier. The Bayaka reported that this is a common behavior, and it was evident from their description
that they had seen i t on several occasions previously. They indicated that this is a
good way to locate and shoot chimpanzees, noting that there is a definite period
312 I Fay and Carroll
when chimpanzees concentrate on honey collection at the end of the dry season.
They claim that chimpanzees exploit many species of bees including honey bees
and several Trigona spp., all a t about the same period. This is the same season that
the Bayaka retreat to “honey camps,” which is concurrent with the major honey
Congo observations (J.M.F.). In March of 1989, in the Republic of Congo,
ca. 75 km east of the Bai Hokou study area, Bayaka trackers discovered a large
fallen branch and began to inspect it for melipone hives, a s they often do. There
they found evidence of where they claimed a chimpanzee had tried to gain access
to a hive. There were broken wood chips at the hive entrance and a piece of dead
wood lying nearby, 20 cm long and 7 cm in diameter, the end of which showed signs
of having been used for prying and ramming. The chimpanzee did not gain access
to the hive due to the hardness of the wood. It was evident from the wear at the
hive entrance that much effort was taken to break into the hive. Subsequently the
Bayaka broke into the hive with a machete and extracted several grams of honey.
In April 1989, near the western border of the Republic of Congo Bayaka guides
pointed out what was said to be evidence of chimpanzees feeding on a ground bee
hive (Trigona (Meliplebia) beccardii) [ex Bahuchet, 19851. The ground had been
broken and obviously worked. Much of the actual comb and what remained of bee
larvae had disappeared in the 3 days the Bayaka said intervened since the hive
was broken. Thirty cm away a piece of wood ca. 40 cm long and 3.5 cm in diameter
was found that was presumably used to break into the hive. This baton was broken
from a sapling, frayed a t both ends, and had probably been used as a digging stick.
The Bayaka consume the honey from this bee, but i t is not preferred because it
gives the consumer diarrhea.
Further evidence of the use of tools by chimpanzees was related by Bayaka
guides. One behavior noted by them that was not observed was the use of sticks
that are put into driver a n t (Dorylus sp.) nests and swarms. These ants attack the
sticks, which are said to be very similar to the termite-mound digging sticks with
brush ends. The chimpanzees are said to consume large amounts of ants using this
method. Certainly, several of the chimpanzee dung samples collected in the Ndakan study area (deposited herbarium, Missouri Botanical Garden) contained a
high percentage of driver ant exoskeletons [see McGrew, 19741.
Northern Site (Bai Hokou, R.W.C. Observations)
Termite mound perforating sticks and termite tunnel probing stalks. In
the Bai Hokou study six sites of termite fishing by chimpanzees were observed in
the form of discarded brush and fishing sticks and rigid perforating sticks accompanied by fresh chimpanzee tracks and droppings. These observations were made
in October-November 1988 and February-May 1989. No termite fishing activity
was noted during the dry months of December and January. Rainstorms are frequent and heavy in October and November, and all observations in February
followed the initial rains of the rainy season (March-November). These probably
moisten and soften the mounds somewhat.
The perforating sticks were made from five species of dicotyledonous trees
(Table I). The sticks were of two kinds, those that appear to be used exclusively for
digging (ca. SO%), and those that appear to be used for digging, but which also
served as fishing sticks. Those that were used for termite fishing had chewed or
frayed ends and those used exclusively for digging had blunt ends.
Tools used exclusively for fishing were made of 6 species, 2 herbs and 4 lianas
(Table 11).In general, the species used for fishing exclusively yield a more slender,
flexible tool unsuitable for perforating even when the mounds are wet. Two tools
Chimpanzee Tool Use / 313
TABLE I. Tools Used for Mucrotermes spp. Mound Perforation and Termite Fishing at
Bai Hokou Study Area
Brush end (cm)
Width (mm)
Length (cm)
Thomandersia laurifolia
Milletia sp.
Strombosia sp.
Polyalthia suaveolens
accounted for almost 70% of those found: Ataenidia conferta and Thomandersia
laurifolia (Tables I, 11).A. conferta petioles are slender and resilient. T . laurifolia
trees produce a large number of slender sticks near the ground; these are straight,
rigid, and unbranched. Both species are common in the study area.
Termite mound digging sticks were often found protruding from Macrotermes
sp. mounds. The termites rebuild around these sticks which become cemented into
the mound and are difficult to remove.
Honey extraction sticks a n d pounding tools. On three occasions in the Bai
Hokou study area dead, fallen branches from large trees were discovered from
which chimpanzees had probably extracted melipone (Trigona gribodoi) honey or
larvae or both. At all three sites fresh tracks of chimpanzees were present. Sticks
ca. 3 cm in diameter were found at each site, close t o the hives, that were presumably used to break into the hollow, partially rotten logs. In all three cases the hives
were obviously broken into and the contents extracted.
On 15 February 1989, two chimpanzees, one adult female and one immature,
were observed ca. 30 m up in a Manilkara sp. (Sapotaceae) tree. The observer
(R.W.C.) was drawn to the tree by the booming sound of pounding on hollow wood.
Upon arrival the adult female was using a blunt stick to open a honey bee hive in
a broken, ca. 30 cm diameter primary branch. It pounded several times with the
stick in the right hand while holding on to the top of the stump with a fully
extended left hand. After several blows with the stick the chimpanzee propped it
up against the stump and reached into the hive to the full length of the right arm.
It then licked honey from her hand, retrieved the pounding stick and inserted into
the hole and slowly extracted it. The female ate the honey off the stick while the
immature chimpanzee approached. The immature was presented the end of the
stick still held by the adult. The immature accepted honey off the stick then
replaced the adult female at the branch stump and reached into the hole with its
hand. At this point the chimpanzees became aware of the observer and moved
higher into the tree without vocalizing.
On March 31,1989, two chimpanzees were observed through thick vegetation.
One individual was sitting and the other was leaning on one elbow while feeding
on something on the ground. After 10 min the chimpanzees became aware of the
observer’s presence and fled. A freshly dug hole ca. 12 cm in diameter and ca. 30
cm deep and a soiled stick ca. 2.5 cm in diameter lay on the ground, which presumably had been used to dig the hole. Honey and hive fragments were scattered
about on the ground. The chimpanzees had apparently dug up a hive of ground
nesting Trigona (Meliplebia) beccardii [ex Bahuchet, 19851bees and were finishing
the remainder of the honey when the observer approached.
No evidence of nut cracking was noted in either study area or in several sites
314 I Fay and Carroll
TABLE 11. Tools Used for Mucrotermes spp. Termite Fishing at Bai Hokou Study Area
Length (cm)
Brush end (cm)
Width (mm)
Ataenidia conferta
Haumania danckelmaniana
Sarcophrynium spp.
Dalhousisea africana
Castandra paradoxa
in Congo where chimpanzees are common, nor mention of this practice was made
by the Bayaka. In thousands of kilometers of travel in these forests since 1986 by
the principal author no evidence of nut cracking has been found. In forests in
northern Congo there are large populations of Coula edulis and chimpanzees. C .
edulis grows in dense stands and produces a large crop of seeds that are exploited
by chimpanzees in west Africa. Other species exploited by chimpanzees in the Tai
forest for their nuts such as Detarium macrocarpum and Panda oleosa are also
common in northern Congo [Boesch & Boesch 1981, 1983, 1984, 19901.
The uses whether observed or inferred from circumstantial evidence in the
above are summarized in Table 111.
The use of both flexible stalks and rigid sticks by chimpanzees in the Central
African Republic is similar to that found in this subspecies in Rio Muni, Cameroon,
and Gabon [Jones & Sabater-Pi, 1969; McGrew & Rogers, 1983; Sugiyama, 1985;
Muroyama, 19913. The termite fishing technique used by the chimpanzees in our
study area most closely paralleled that found by McGrew and Rogers [1983] in
Gabon where chimpanzees use flexible stalks, similar to those of Ataenidia conferta, but of different species.
Our observations of sticks at the base of termite mounds indicate that chimpanzees revisit the same “fishing holes” repeatedly. In addition, i t appears that
chimpanzees may maintain these sites by leaving sticks or stalks in the fishing
holes. While it was not confirmed, it seems likely that when chimpanzees return to
a site where sticks are incorporated into the mound matrix, they merely pull the
obsolete stick from the hole and immediately start fishing for termites in a n appropriately sized hole with a fresh probe. Discarded sticks that have been incorporated into the mound matrix have been noted in Cameroon [Sugiyama, 19851.
Chimpanzees are known to revisit invertebrate food sources and to repeatedly use
the same tool [McBeath & McGrew, 1982; Uehara, 1982; Anderson et al., 1983;
Bermejo et al., 19891.
Chimpanzees are confronted with a large number of plant species from which
to make tools. The data presented here indicate that the chimpanzees studied do
not select plants species a t random but are very specific in their choice of tools. The
two species used in the majority of cases for extracting termites in both study sites
are often found at the same “fishing hole” and have complimentary uses. Thomandersia laurifolia is the plant of choice used as a perforating stick, and
Ataenidia conferta petioles are the predominant fishing sticks. Each has physical
characteristics well suited to the task. It is likely that the use of these two species
Chimpanzee Tool Use / 315
TABLE 111. Types of Tools Found at Different Sites in the Central African Republic
and Congo
Central African Republic
Termite mound
Perforating stick
Fishing stick
Bee Hive
Digging stick
Prying stick
Pounding stick
Bai Hokou
E Bai Hokou
Gabon Border
= observed, i = inferred.
has resulted from a process of trial and error in a search for appropriate tools to fit
the physical task. Muroyama [1991] came to a similar conclusion.
While the use of tools to obtain honey and larvae has been reported in all three
subspecies of chimpanzee [Merfield & Miller, 1956; Yamagiwa et al., 1988; Bermejo, et al., 1989; Brewer & McGrew, 19901,the use of large pieces ofwood to break
into bee hives has previously been reported only for a single rehabilitated P. t.
uerus in the Gambia [Brewer & McGrew, 19901. According to Bayaka guides, who
are very accurate in their description of natural history, it is a common behavior
used to penetrate the nests of many species of bees. This behavior was recorded
involving a species of small tree-nesting melipone bee, honey bees, and a species of
ground-dwelling bee. More significant is the fact that this behavior occurs over a
large geographical area.
There is considerable inter-populational variation in the use of tools by chimpanzees, even within a subspecies [Sugiyama, 19851. The observations presented
here indicate that tool use differs between the eastern (CAR, Congo) and western
(Cameroon, Gabon, Equatorial Guinea) sectors of the range of P. t. troglodytes.
While the types of tools used to extract termites found in this study are functionally similar to those found in the western sector of the P. t. troglodytes range, the
plant species used are quite different. The majority of plant species used for termite
mound perforation and fishing are found throughout the range of P. t. troglodytes.
Our observations indicate that honey extraction from a variety of bee species is
widespread in the eastern range of Pan t. troglodytes. This behavior has not yet
been reported for the western part of its range [Merfield & Miller's 1956 report
came from somewhere east of Yaounde, Cameroon], where many more observations have been made on chimpanzee tool use. Melipone and honey bees are common throughout the range of P. t. troglodytes. No environmental factor that differs
between the east and west of the range of P. t. troglodytes that would cause the
difference in tool use was identified.
1. Chimpanzees in the eastern range of P. t. troglodytes used tools to extract
termites that are functionally similar to those found in the western sector of the
P. t. troglodytes range, but employing different plant species. The majority of plant
species used are found throughout the range of P. t. troglodytes.
316 I Fay and Carroll
2. Preferred species used for termite mound perforating sticks differ from
those used for mound probing in the eastern range of P. t. troglodytes.
3. It is possible that chimpanzees in the eastern range of P. t. troglodytes
exploit the same access holes on a single mound repeatedly and may maintain
“fishing holes” by plugging with perforating sticks.
4. P. t. troglodytes use large wooden pounding, prying, and digging tools to
gain access to hives of several species of arboreal and ground dwelling bees in
several sites in the eastern part of its range.
This work was done during the course of studies on western lowland gorillas.
We thank the following organizations for their generous support of that work:
NYZS/The Wildlife Conservation Society, National Geographic Society, L.S.B.
Leakey Foundation, World Wildlife Fund-US, Missouri Botanical Garden, Washington University, and Yale University. We also thank the governments of the
Central African Republic and the Republic of Congo for permission to carry out
research in their countries. Richard Ruggiero is thanked for his useful comments
on the original manuscript.
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