American Journal of Primatology 34309-317 (1994) BRIEF REPORTS Chimpanzee Tool Use for Honey and Termite Extraction in Central Africa J. MICHAEL FAY' AND RICHARD W. CARROLL' 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 INTRODUCTION 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. METHODS 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. RESULTS 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 mounds. 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 flow. 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) Species n X SD n x SD n Thomandersia laurifolia Milletia sp. Strombosia sp. Polyalthia suaveolens Unknown 65 3 2 2 2 56.5 92.3 49.5 64.8 80.1 16.4 13.6 17.4 28.1 31.7 64 2 2 2 2 13.2 5.7 4.1 6.0 5.7 2.5 0.5 2.0 0.1 1.4 Total 74 58.7 18.3 72 12.3 3.5 x SD 8 3 1 2 1 4.2 3.4 1.9 2.4 1.9 2.3 1.6 15 3.5 2.0 0.2 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) SDecies n x SD n x Ataenidia conferta Haumania danckelmaniana Sarcophrynium spp. Dalhousisea africana Castandra paradoxa Unknown Total 29 18 7 6 1 1 56.6 45.7 41.8 48.5 24.4 60.3 15.2 21.8 8.4 13.0 17 13 3 6 1 1 4.8 3.7 2.7 3.9 6.0 3.6 62 50.5 17.5 41 4.1 S D n x SD 1.0 0.8 0.9 1.0 28 9 3 4 19.8 4.9 12.0 13.1 17.5 5.5 12.7 15.8 1 9.6 1.1 45 15.4 16.0 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. DISCUSSION 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  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 Site" Central African Republic Tool Termite mound Perforating stick Fishing stick Bee Hive Digging stick Prying stick Pounding stick a. Ndakan Bai Hokou i o,i i i i i 0 Congo E Bai Hokou Gabon Border i i 0 = observed, i = inferred. has resulted from a process of trial and error in a search for appropriate tools to fit the physical task. Muroyama  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. CONCLUSIONS 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. ACKNOWLEDGMENTS 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. 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