IBED and the Bili Apes

AUGUST 9 ­ DECEMBER 24, 2004
First day at Camp Louis: August 18, 2004
First day collecting field data: August 21, 2004
First break in data collection, return to Bili Village: Oct. 1-6, 2004
Total of 40 days of data collection.

Project Goals:

The primary goal of Project Mukumbusu is the habituation to the presence of researchers a community of chimpanzees (Pan troglodytes schweinfurthii) living in the forest/savannah mosaic region approximately 34 km northwest of the village of Bili (Democratic Republic of Congo). Habituation will facilitate research into the demographics, socioecology, and behaviour of these chimpanzees. Already much evidence has been gathered regarding the unique culture of these apes, which includes the regular construction of terrestrial night nests, the use of extremely long branches as ant-dipping tools, and the use of leaves as cushions on which to sit during the day.

In the future, systematic transects will be surveyed to determine chimpanzee population densities and distribution in the area. Extrapolation from this planned transect research to the to the wider North-Central DRC region is expected to provide crucial information relevant to the conservation status of Pan troglodytes in Central Africa. DNA gathered from the dung and hairs of the chimpanzees from both this field season and previous ones will help elucidate the genetics and taxonomic position of this population.

The project operates within the framework of the conservation effort put into place by Karl Ammann, who first documented many of the unique features of these apes, and the Wasmoeth Wildlife Foundation. Currently a research collaboration has begun with the University of Amsterdam, at which the primary field researcher Cleve Hicks is enrolled as a Phd student.

The study area covers roughly 9 km W-E between the Dikpai and Ze Rivers, and 7.6 km S-N between the Nagbakomo and Tuu Rivers (68.4 km sq.). The nearest Azande villages are Badai and Pangali, which are located approximately 10 km E and 9 km NE of Camp Louis respectively. Human use of the region, other than the yearly burning of the savannahs, is minimal. This complex mosaic habitat consists of seasonally-burned savannah, savannah-woodland, regenerating forest and gallery forest. Other than chimpanzees, the area is rich in African fauna typifying both savannah and forest habitats, including: elephants, lions, hyeanas, leopards, giant forest hogs, giant pangolin, baboons, grey-cheeked mangabeys, red-tailed guenons, and buffalo.

So far, the monitoring of daily rainfall at the study site has revealed a sharp contrast between the rainy and dry seasons. Between October 11 and November 22 we received a total of 7595.7 ml of rainfall, averaging 176.64 ml per day (SD = 292.187 ml). From November 23 to December 24 we received 0 ml. The rains ended abruptly, with 1425 ml falling on November 20, 112.3 ml on November 21, 1 ml on November 22, and not a drop after that date. Recording of minimum and maximum daily temperatures awaits the construction of a Stevenson’s screen (currently underway at Bili), but night-time temperatures appear to be cooler and day-time temperatures hotter in the dry season than in the wet.

Several methods are used to contact the chimpanzees. Each night a team consisting of a data recorder (usually either Cleve Hicks or Camp Manager Makassi) and a tracker sleeps at the satellite camp 5 km W of Camp Louis, in the area where chimpanzees have most often been seen and located (chimpanzees are also contacted from Camp Louis, if heard close enough to camp). Upon hearing chimpanzee pant-hoots or tree drums, the team leaves camp early in the morning, sometimes using flashlights, to try and locate and contact the chimpanzees. In addition, fruiting trees such as strangler figs, which are visited often by the chimpanzees, are staked out during the morning hours. If chimpanzees are not heard and no fruit trees can be located, the team follows trails cut along the riverbeds looking for fresh signs of chimpanzees and listening for their calls.

Detailed videos, photos, and written records are kept of all contacts, nest sites, feeding remains, and other chimpanzee evidence found, as well as that of other large mammals. DNA samples from chimpanzee dung and hair are collected, and all dung samples are weighed, washed, and the contents are analyzed and saved. Feeding remains are saved as well, for future identification by specialists at the university. Finally, hidden trip-activated cameras have been set out in strategic places to capture images of chimpanzees and other wildlife.


As of December 24, we have had 39 contacts with the chimpanzees in the study area, a contact being defined as a period of time in which the chimpanzees and the observers are aware of one another. An encounter is only counted as a contact if there is sufficient evidence to know whether the apes were aware of the observers’ presence.

TOTAL CONTACT TIME: 614.7 minutes
AVERAGE CONTACT DURATION: 15.76 minutes (SD = 26.24 minutes)
MINIMUM: .1 minutes
MAXIMUM: 102 minutes

On average we have contacted the chimpanzees once every 3.2 days of the first four months of this field season, and spent an average of 4.92 minutes with them per day. For 28 of the 39 contacts Cleve Hicks was present (555.6 minutes, averaging 19.84 minutes per contact, SD = 29.52), and the majority of these are recorded on film. The other 11 contacts were conducted by the Bili trackers and Camp Manager Makassi (approx. 59.1 minutes, averaging 5.37 minutes per contact, SD = 9.9 ­ this is certainly an underestimate, see below). For 6 of these 11 contacts, the Camp Manager (who has been trained to take basic data as well as record GPS points) was present, and for 5 only trackers were present. Four of these 11 contacts were recorded on film. For these contacts approximations of the contact duration had to be made based on the films and information provided by the trackers and the Camp Manager. In these cases the most conservative estimate for contact duration has been made. For example, one contact was recorded by Makassi as having lasted exactly 10 minutes, but only 2 minutes were recorded on film. As Makassi seemed to have estimated the contact time and not used exact watch time, the bare minimum 2 minutes as recorded on film was counted as contact time, although the contact probably lasted much longer. Currently the trackers and Makassi are being provided with watches and instructed on how to properly record contact duration.

Over the course of the study to date, the number and duration of contacts can be grouped into the following one-month time periods:

Period 1, 8/22 ­ 9/21:
5 contacts totalling 214.5 minutes contact time, averaging 42.9 minutes per contact (SD = 39.08): on average 6.9 minutes were spent in contact per day. In addition there were 16 minutes of observation time.

Period 2, 9/22 ­ 10/21: 11 contacts totalling 214.2 minutes contact time, averaging 19.47 minutes per contact (SD = 21.7): on average 7.14 minutes were spent in contact per day. In addition there were 15.7 minutes of
observation time.

Period 3, 10/22 ­ 11/21: 11 contacts totalling 41.5 minutes contact time, averaging 3.77 minutes per contact (SD = 6.51): on average 1.3 minutes in were spent in contact per day. In addition there were 62.5 minutes of
observation time.

Period 4, 11/22 ­ 12/21: 12 contacts totalling 144.5 minutes contact time, averaging 12.04 minutes per contact (SD = 29.13): on average 4.82 minutes were spent in contact per day. In addition there were 39 minutes of observation time.

As can be observed, the number of contacts per month increased from 5 in the first month-long period to 11 in the second, and remained about the same over the following two month-long periods. However, contact time and number of minutes spent in contact per day decreased substantially in the third month, recovering only partially in the fourth month. Interpretation: as the study progressed we became better at locating and contacting the chimpanzees, particularly once we began focusing on the western area. In the first month contacts were few but tended to last a long time. A possible explanation for this was the tracker’s initial inexperience with contacting the chimpanzees, leading them to ‘tree’ frightened females for long periods of time, by getting too close to the trees, making aggressive noises, etc. As a result the chimpanzees seemed to scatter or leave the area and we would then have difficulty finding them for the next several days (hence the smaller number of contacts).

As the chimpanzees and ourselves got more familiar with one another (and the trackers received contact-etiquette training from Hicks), the chimpanzees tended to leave the trees upon becoming aware of us, but to not flee very far, enabling us to locate them later in the day or the following day for a second contact, thus increasing the overall number of contacts. The staking out of fruiting trees, started in Period 3, enabled us to have many contacts at the same fruit trees over a period of several days. This strategy was particularly successful at fig trees, with 3 trees producing respectively 7, 4, and 3 contacts over three one-week-long periods in November and December.

Another factor that may explain the fewer in number but longer-lasting contacts in the first 2 periods is that chimpanzee party size appeared to be much larger in the first 2 months (the wet season) than in the last 2 months: Period 1­ avg. 5.8 individuals seen per contact, Period 2 ­ avg. 3.27 individuals seen per contact, Period 3 ­ avg. 3.18 individuals seen per contact, Period 4 ­ average 2.7 individuals seen per contact. These progressively smaller party sizes may have led to contacts of progressively shorter durations, because when party sizes were large in the early months, we would often wander from subgroup to subgroup of the large, spread-out parties, contacting many different individuals, while in the later months there appeared to be many fewer individuals per party, often all in one tree, leading to shorter more concentrated contacts. It should be noted that our longest contact to date, at 102 minutes, happened at the end of the fourth month, and that 2 other contacts in this period (with the adult female Caroline) lasted 7 and 24 minutes respectively.

An observation is defined as a researcher or tracker observing chimpanzees without the chimpanzees being aware of the human’s presence. 136.15 minutes of observation were recorded in total over the 4 month period.

Cleve Hicks had 102.85 minutes of observation in association with contacts, and the trackers/Makassi without Hicks had a minimum of 28.3 minutes of observation in association with contacts (as with the contacts, for the trackers/Makassi, this is probably a large underestimate ­ an attempt was made to use the most conservative measure possible). In addition, on three occasions trackers observed the chimpanzees without later contacting them, for an estimated 5 minutes observation time.

In addition to contacts and observations, a total of approximately 10,664 minutes of auditory observations of the chimpanzees were recorded (n = 110). A single auditory observation is considered to be hearing tree drums and/or vocalizations in a particular forest region during a one-day or overnight period. Approximately 7000 minutes of auditory observations were recorded in association with contacts (5, 606 minutes with Cleve Hicks present, n = 25, and approximately 1,394 minutes with the trackers and/or Makassi only, n = 7), and another 3,664 minutes without associated contacts (n = 78) (2,752 minutes with Cleve Hicks present, n = 54, and another approximate 911 minutes with the trackers and/or Makassi only, n = 24).


As of this date, we believe we have achieved individual recognition of one adult female chimpanzee, whom we have named Caroline. She appears to be an extremely aged individual, with greyish white hair on her lower back and belly and a bald scalp, and unmistakeable hollow cheeks giving her a gaunt appearance. She appears to be very large, especially for a female, but also quite frail and bony, particularly in the pelvic region. She moves very slowly. We believe we first saw her on September 23, 2004, when we encountered her alone in the NW of the study region with her cheeks stuffed full of leaves. Two night nests, one from that day and one apparently from the previous day, were present at the contact site, giving us the impression that this female had slept alone at the tree for two days. This contact lasted for 31 minutes as the female slowly moved off through the trees to the W. We next encountered Caroline about 1.5 km to the E at the Nambala River on the 5 ecember, where we found her feeding on Likuyo fruits. She remained in the tree for 24 minutes as we contacted her, apparently still eating the fruits. Towards the end of the contact she had stopped eating and sat hunched in the tree above our heads, before finally moving into a neighboring tree. What was clearly the same lone female individual was contacted for 6.5 minutes at a fig tree on the 18 December only about 300 m E of the Likuyo.

During the last two contacts described, this female moved with agonizing slowness, much as Flo at Gombe did during her last year or so of life. She appears to be remarkably unphased by our presence, and often sits and watches us for many minutes at a time (she may be simply too old to flee!). We have recorded her on film during each contact, and we have never seen her in the company of another individual. Because of her large size, the trackers have misidentified her as a male on two occasions, while the video footage clearly shows her to have deflated female genitalia. Another possible contact with Caroline (or a similar large, solitary, aged female) occurred in a nearby fig tree on November 18. For 4.5 minutes I observed a large, slow-moving female picking her way along a branch towards the N, and although I could not see her face or film her, my hunch is hat this too was Caroline.


All of the contacts took place within a 70 km sq. area roughly enclosed by the Banga River to the E, the Nagbokomo and Nagbalama Rivers to the S, the Dikpai to the W, and the Tuu to the N. Omitting one outlier contact just to the E of the Banga River, 38 contacts took place within a 49.5 km sq. area limited by the Ze to the E. 34 of the 39 contacts occurred from the Dkpito River west to the Dikpai (21.12 km sq.), and 31 of the 39 occurred between the Musali and Dikpai Rivers (12.5 km sq.). It is the opinion of this researcher that the most productive area for contacting chimpanzees is the Dikpai/Nambala/Nabilingba region, and it is here that a new camp should be established (the mapping program MapSource was used to acquire the areas given above). The chimpanzees have so far maintained a close proximity to the streams, primarily the Dikpai, Nambala, Nabilingba, Tuu, Musali, Dkpito, and Ze. It thus appears that they are heavily tied to the gallery forests. However, evidence of chimpanzee presence in the form of dung and footprints has been found in the savannah-woodland and regenerating forest regions between Musali and Dikpai, and in one case fresh chimpanzee tracks were found at the very edge of the Dkpito savannah. According to the local trackers, the chimpanzees will begin to visit the savannah region more frequently during the dry season, to feed on fruits there. At the same time, they are expected to retreat each night to the river beds to sleep.


In general the younger juveniles and subadults have been least afraid of the observers, often peering at the camera with apparent curiosity and sometimes even approaching arboreally to get a better look. Over a 30-minute period during the 102-minute long contact of the 19 December, a juvenile approached from approximately 100 m to the S to within 10 m of the researcher and tracker, screaming aggressively and staring directly at the humans while displaying. In this same contact, after calmly observing the humans for more than an hour and a half, an arboreal adult female and associated infant passed directly above the researcher and trackers’ heads, and the female defecated on top of the researcher before slowly moving off! In general, adult females have shown moderate fear and/or arousal, but have often remained overhead in the trees for up to 100 minutes observing (and in the early days screaming at) the human observers. On all but two of at least six occasions, when adult males have been encountered in the trees they have immediately leaped to the ground and fled. The exceptions were two contacts, one in October and one in November, in which adult males showed moderate curiosity towards the human observers and remained to observe us for approximately one minute before moving off. When they have been encountered on the ground they have fled immediately as well. Of all age and sex classes, adult males seem to be the most afraid of humans (so much for them being giant savage killers that hunters dare not pursue!).

So far, naturalistic non-feeding observations of the chimpanzees have been difficult to come by, as contacting them has been a focus of the work and during contacts they always react to the presence of the observers. However, during a rainstorm on November 16, an adult male was observed by Cleve Hicks engaged in what appeared to be a rain dance (an active display, for 2 minutes leaping about in the branches of a fig tree while the females and juveniles huddled in the rain), a behaviour that has been observed in several habituated chimpanzee communities in Africa (unfortunately it was not possible to film this dance as the downpour was too heavy). In addition, the trackers Ligada and Kongwonyese reported on December 6 hearing a party of chimpanzees erupting into pant-hoots for an hour in response to the pre-dawn roar of a lion. It is expected that more observations of social behaviour will be made as the habituation progresses.

A possible example of symbolic communication: On at least 6 occasions, a chimpanzee has been heard drumming or stamping repeatedly and rapidly, sometimes on a tree buttress but most often on the ground, followed by the rest of the individuals in the party promptly descending from the trees and moving in the direction of the drum. In fact, hearing this distinctive form of a drum (not as exhuberant and long-lasting as the tree drums made during the night on tree buttresses) is usually a sign for us that our window of opportunity for an arboreal contact is fast coming to a close. There are several indications that these drums are made by adult males, who thus may be responsible for directing the travel of the group, but this has yet to be confirmed. This behaviour, if indeed it is symbolic communication (‘Come on, ladies, let’s go!’?) is reminiscent of the possibly symbolic tree-drumming behaviour described by Boesch and Boesch-Achermann (2000) of the adult male Tai Forest chimpanzee Brutus.


In the eyes of this researcher, the Bili chimpanzees show no marked physical departures from chimpanzees of other populations, with the possible exception of a larger body size. There appears to be variation in skin and coat coloration, typical for the species, ranging from light-skinned adults and sub-adults to black-faced adults with black or greyish hair. Many of the adult females appear to be bald. The adult males do appear to my eye to be larger than the average chimpanzee male, although I doubt nearly as large as gorilla males. I have obtained one film of an adult male moving on the ground towards the camera, and he seems quite a bit bigger than the other individual (probably an adult female) in the frame with him. At least one adult female, Caroline, as described above, seems to be very large herself. As for previous reports to the media of flat-faced, round-headed features, and females without pronounced sexual swellings, I have acquired many films of adult male and female chimpanzees with the normal prognathic jaws of P. troglodytes, and several films of adult females with pink sexual swellings.

However, because the males are so timid it has been difficult to get a good look at them, and it cannot be ruled out that some physical differences between them and the males of other chimpanzee populations may be found to exist. The 5 footprints we have measured have been 18, 25, 26, 27.7 and 28 cm in length, but casts of considerably larger footprints have been acquired by Karl Ammann and other researchers in previous years. In addition, several dung samples collected this season seem to be much larger and heavier than anything recorded for chimpanzees elsewhere. An amazing 1285 g of dung was found at one ground nest, with 869 g from the morning and 416 g from the previous night. The morning dung had hostra rings like the dung of gorillas. Two intact logs of this dung measured 4 and 6 cm in circumference. Another large single piece of dung found at a contact site weighed 231 g and measured 8 cm in circumference. Following another contact, we found a large fresh dung sample (230 g for the single piece), measuring an incredible 8.7 cm in circumference, with hostra rings!

Finally, 291 g of rain-decayed fresh dung was found at another ground nest. Such massive and copious dung points to the possibility that we are dealing with chimpanzees that are either or a much larger size than normal
or at the very least have unique specializations of the digestive system (see Diet, below).


Perhaps the most puzzling feature of this population of chimpanzees is their regular construction of large, intricately-constructed ground nests, which Karl Ammann has been documenting and photographing for many years. These nests have regularly been found in or near river beds, in thick Marantaceae vegetation, in every part of the study region. Originally their presence, along with evidence for the large size of some of the apes and the hostra rings of the dung associated with the nests, led to speculation that a population of gorillas or gorilla-chimp hybrids might be co-inhabiting the area with smaller tree-nesting chimpanzees. The DNA evidence to date, however, indicates that only Pan troglodytes schweinfurthii inhabits these forests, and this species is responsible for both the terrestrial and arboreal nests that have been found.

Knowing this, we can still ask the question: what socioecological, climactic, or cultural factors lead this population of chimpanzees to construct ground nests as well as tree nests, when in all other chimpanzee populations studied to date tree nests are the norm (there are a few cases of chimp ground nests at Bwindi and in West Africa)? This question becomes even more puzzling when one considers the presence of so many potentially dangerous nocturnal animals wandering through the same forests and river beds in which the chimpanzees bed down at night. Buffalo are numerous, I have observed fresh elephant trails traversing the same tangled swamp patches in which fresh ground nests have been found, and we hear hyeana and leopard calls almost every night, and more rarely lion roars (in addition we have found a lion print, as well as many hyeana prints in the savannahs; leopard prints are regularly found in the mud of the river beds). This seems to be the last place in Africa a chimpanzee concerned for his or her safety would want to bed down on the ground, and yet we regularly find these terrestrial nests.

The first question we can ask is: are the ground nests night or day nests? Undoubtedly, some of the ground nests were day nests. We have found three recently-used solitary ground nests showing very simple, unsubstantial construction using Marantaceae or tree leaves mostly placed in flat piles. These nests did not look worn or slept in, when fresh had no associated dung, and were not found in association with tree nests. Although it is difficult to be sure, in these cases the trackers and I had little doubt that we were looking at day nests. However, at 15 other nest sites, we have found recently-constructed ground nests (from one to four) which almost certainly dated from the same time period (within the past week) as a number of associated tree nests or other ground nests.

These ground nests were often built with relatively elaborate construction, using either interwoven Marantaceae or many saplings (or both) bent down into a central bowl. In some cases tree branches were ripped off and woven into the bowl (the other 10 nest sites at which ground nests were found were ambiguous, ie. the sites were very old, or the ground nests were loosely and minimally-constructed but in association with one or more other nests). It seems unlikely (but not impossible) that five or more chimpanzees would have all decided to make day nests in the same spot on the same day, with some making nests in the trees and some making them on the ground, with each nest showing relatively complex construction. It cannot be ruled out, however, that a chimpanzee might revisit a night nest site used a few days earlier and construct a terrestrial day nest there. Crucial for determining whether or not ground nests have been slept in overnight would be the examination of fresh nests vacated the morning of their discovery, ideally associated with fresh dung.

Until November of this field season, however, only ground nests of several days’ age had been found. The discovery of four fresh sites in November and December, two in the Nambala river bed and two in the dry-ground forest just N of the Nambala, allowed for some more definitive conclusions. In the early morning of 13 November, following a contact in a fig tree with several chimpanzees including what was probably an adult male, we discovered a nest site a few hundred meters to the N in the river-bed. In addition to five old brown tree nests, we found four fresh green tree nests vacated that morning, with dung from the morning as well as slightly decayed dung from the previous evening on the ground beneath two of them. Approximately 12 m from one of the tree nests was an elaborately-constructed ground nest made of gole fronds. An incredible 1285 g of faeces was found in and around the rim of this nest. About half of the faeces (869 g) had clearly been deposited in the morning, as the fresh condition and clearly-defined hostra rings attested. The rest of the dung (416 g) was of a mushy consistency, of a different color, and had been partially decayed by the activities of beetles and other insects ­ this had been deposited the night before.

This nest provided definitive evidence that at least some of the ground nests are slept in overnight, in nest-groupings with arboreal nests. Three days later, following another early-morning contact with an adult male and some females at the same fig tree, another fresh, well-worn ground nest was found within 50 m of the first, constructed from dukpe leaves, once again with fresh dung in the nest. The dung had been rained on, and considering that the rain began at 7:36 am while we were watching the chimpanzees in the fruit tree, the nest almost certainly had been vacated in the early morning and thus was a night nest. Two tree nests were also found nearby, probably made the previous evening, although the lack of dung beneath them made it difficult to be certain of this. At 10 am on November 30, approximately 900 m N of this site, in the dry-ground forest near a fruit tree at which the chimpanzees had fed in the morning, a nest site was found with 3 fresh tree nests and a ground nest constructed from saplings (with the branches interwoven in an elaborate manner). Fresh dung from the morning was found beneath two of the tree nests and beside the ground nest. The most likely explanation is that this was a night nest site. Interestingly, what was probably a fresh day nest of much less-elaborate construction (basically some small branches ripped off and placed in a pile on the ground), with no dung but chimpanzee hairs present, was found approximately 200 m SW of this nest site. A leaf cushion, also with a chimpanzee hair on top, was found nearby as well (it should be said that the distinction between a day ground nest and a leaf cushion is somewhat arbitrary ­ day ground nests are simply slightly larger and more elaborate than cushions, which are usually just leaves placed on the ground). Based on the above evidence, it is my tentative conclusion that all fresh or recent nest sites we have found that are a mixture of tree nests and elaborate, well-worn ground nests are night nest sites.

Nest sites were searched for unsystematically, usually in the process of looking for the chimpanzees themselves. Some nests were found when dry-ground forest as well as river beds were combed for nests following contacts, but others were found randomly when cutting new trails or travelling in the direction of pant-hoots. In addition to the 347 nests found by Cleve Hicks, Camp Manager Makassi has also filmed and documented a number of ground and tree nests. However, to rule out possible differences in data collection methodology, for the following analyses only those nests found and measured by Hicks will be considered.

We have found 347 individual nests at 125 nest sites (a nest site is considered all nests appearing to date from the same age within an area not separated by more than 25 m). The average height of the 295 of these nests for which height was recorded (estimated by Cleve Hicks, who has considerable experience doing this, but should nevertheless be reliability-tested), when ground nests are not included, is 7.03 m (SD = 4.73), considerably lower than that of chimpanzees at many other sites. 38 of the 347 individual nests were ground nests, found at 28 sites (defined here as any nest built below .75 m elevation), approximately 9% of nests. Including these, the average nest height is 6.23 m. Only 8 nests have been found that were built higher than 15m elev.

It seems likely that ground nests decay more rapidly than tree nests. When looking only at the 121 fresh or recent nests (nests which are still green and have not started to decay), 22 of these were ground nests (18 %).
Percentage-wise, this is twice as many as found when including older nests. Three nest sites located on the day they were slept in and containing both tree and ground nests have now been documented, and these will be revisited at periodic intervals to give us a better understanding of nest decay rates for tree and ground nests.

All but 5 of these 22 fresh or recent ground nests were found with other ground or tree nests from the same apparent time period nearby. With only 4 exceptions (all solitary nests), they appeared to have been solidly constructed. Out of the 46 fresh or recent nests sites, 17 (37%) had at least one ground nest present, while 29 sites had none.

The average number of ground nests per site: For fresh or recent nest sites, there was an average of 2.72 (SD = 2.7) nests per site total: this includes 0.48 (SD = 0.75) ground nests per site. When only including sites with ground nests present, there were 1.3 (SD = 0.69) ground nests per site. Of the 22 fresh or recent ground nests found, 3 (14%) were found in open dry-ground forest, 7 (32%) were in river-bed forests, 5 (23%) were in medium dry-ground forest, and 7 (32%) were in dense dry-ground forest. Looking at ALL ground nests found, fresh and old, out of the 37 for which forest-type were recorded, 8 (22%) were in dense dry-ground forest, 9 (24%) in open dry-ground forest, 5 (13.5%) in medium dense dry-ground forest, and 15 (40.5%) in river-bed forest. In comparison, for fresh and recent tree nests, 35 (35.7%) were found in open dry-ground forest, 21 (21.4%) were in river-bed forest, 12 (12.2%) were in medium dry-ground forest, and 30 (30.6%) were in dense dry-ground forest. For ALL tree nests, old and fresh, 60 (19.6%) were found in dense dry-ground forest, 62 (20%) were in river-bed forest, 57 (18.6%) were in medium dry-ground forest, and 127 (41.5%) were in open forest. Although statistical tests have not been performed, it seems that ground nests were more likely to be
found in river-bed forests than tree nests. Considering the low surface-area covered by river-bed forest compared to the other forest types, it would appear that the chimpanzees have a preference for making ground nests there. Based on what the trackers have told us, we are expecting to see the chimpanzees nest more in the riverbeds during the dry season.

Size: The average size for the 31 ground nests for which measures were taken was 104.17 X 86.43 cm.

Materials: Of the 36 ground nests for which data are available, 8 used only Megaphrynium stems in their construction, 1 used only Afromomum, 5 used a combination of Megaphrynium and saplings, 1 used a combination of Afromomum and saplings, 19 used only small saplings, either bent over into the nest or ripped off and placed on the nest, and one each used Gole or Dukpe herbs (Azande names). Megaphrynium was thus used in the construction of 36% of the ground nests. Of the 15 ground nests found in river beds, 5 used exclusively Megaphrynium, 2 used a combination of Megaphrynium and saplings, 4 used exclusively saplings, and one each used exclusively Afromomum, Dukpe, or Gole (and once Afromomum was used in combination with saplings). In the riverbeds, Megaphrynium was used to construct 47% of river-bed ground nests.


20 tools apparently used by chimpanzees have been found at 6 tool sites. All of these tools were found in association with subterranean ant nests, and were apparently used to dip for the ants. On two occasions, ants were still present at the nest and could be identified as driver ants (Dorylus sp.), and when the tools were collected the ants swarmed quickly up their lengths and viciously bit the researcher. The abandoned ant holes at the remaining tool sites were also identified by the trackers as belonging to driver ants (ngbaka or ‘red ants’ in the Azande language), with the exception of one which was identified as belonging to bokunjio ants. The majority of the tools were found inserted up to half of their length into the ant holes, with the proximal ends sticking up into the air. The tools were almost always stripped on both ends, with leafy sections usually but not always removed. Several of the tools were squashed out in a fan shape on their distal ends, resembling ‘brush sticks’ described at other sites. It is not known whether they were fashioned this way deliberately by the chimpanzees or if it was an unintentional result of jamming them into the ant holes. Average tool length was 89.09 cm (SD = 29.1), with the longest tool measuring 149.2 cm and the shortest 54 cm. 4 tools measured over one meter in length. These are possibly the longest tools used for ant-dipping so far seen in Africa, and most are better classified as branches than as twigs. Average midpoint circumference was 3.46 cm (SD = .86), or 1.10 cm diameter; average proximal end circumference was 3.16 cm (SD = .82), or 1.01 cm diameter; average distal end circumference was 3.28 cm (SD = 1.03), or 1.05 cm diameter. With two exceptions, all of the tools were constructed from the detached sections of nearby saplings, which were usually found within one meter of the ant holes.

At each tool site a different tree species (at least, as identified by its Azande name) was used as the raw material. Two tools were constructed from the stems of Megaphrynium, the locally-abundant Marantaceae which the chimpanzees frequently use to construct their ground nests. The exoskeletons of ants have been found in two dung samples, in one case making up approximately 18% of the sample (these were apparently driver ant exoskeletons, although this needs to be confirmed by an expert).

Although several nest-building termite species are present in the savannahs and forests of the study area, there is to date no evidence of chimpanzees using tools to acquire them, and the trackers say they do not do this. The chimpanzees do appear to break open the numerous small mushroom-shaped termitieres, however, and eat the termites. So far no termite parts have been found in the dung wash samples.

We have also found on four occasions leaves used by chimpanzees as cushions, similar to what has been described at Bossou. Although similar to terrestrial day nests, these cushions consist of only a few leaves placed on the ground without arrangement or construction (we humans sometimes do the same thing during contacts). Day and night ground nests, on the other hand, involve at least a minimal weaving together of branches. On top of one of the leaf cushions we found a chimp hair, which was saved for DNA analysis. Another cushion was associated with chimpanzee prints.

Films and photos have been taken of all of the tools described above. Both Camp Manager Makassi and tracker Futio have independently claimed to have witnessed a tool use behaviour which, if confirmed, would be a new discovery, not described in any other chimpanzee population. In filmed interviews, they describe how years before they each observed, in separate incidents, a chimpanzee pounding into an arboreal bee hive with a stone in order to obtain honey. Both witnesses claim to have scared the chimpanzee away and confiscated the honey, and found the stone tool at the base of the tree. If confirmed this would also be, as far as I know, the only instance of East African chimpanzees actively using stones in a subsistence activity (and not just as a substrate).


Currently our study of the diet of the Bili chimpanzees is in itsinfancy, as we await expert identification of the vegetation types eatenby the apes. Examples of chimpanzee feeding remains are regularly collected and saved for future identification. In addition, 28 dung washes have been conducted since early October , in which dung samples collected at nest sites, contact sites, or on the trail have been saved, weighed, washed, and dissected. All plant and animal remains found within the dung are identified by their Azande names, the proportion of each component of the dung by weight is established, and the remains are stored in plastic bags. The chimpanzees have been directly observed (and filmed) on several occasions in the trees eating fruits or leaves: most commonly strangler figs between the months of November and December, but also Vwole-Vwole (Uapaca?) in October, Likuyo and Dondoli in December, as well as the leaves of trees on several other occasions.

After the majority of arboreal contacts, copious fresh feeding remains have been found beneath the contact trees. Although the results have yet to be systematically analyzed, the dung washes show that between the months of October and early November the dung was generally full (often to 100%) of the seeds of vine fruits, including Defu (presumably a Landolphia species), Limongule, and Linde, vine fruits being also the most-common feeding remain found from late August until late October. After this, the amount of vine fruit decreased dramatically in the dung as well as in the feeding remains, with only the Buta vine seeds showing up in the dung on occasion (the other vine fruits being no longer in season). At this point our contact as well as dung wash records show that the chimpanzees began turning regularly to strangler fig fruits. The tiny seeds of the figs began to show up regularly, interspersed throughout the dung. However, it seems that fig was only one of the fallback foods that the chimpanzees began taking advantage of as the vine fruit crops disappeared. Fiber began to show up in much larger proportions in some of the dung samples after November (up to 60% of the sample) ­ of the 15 samples washed after November 13, 4 had over 25% fiber and 5 had over 10% fiber (2 of these were from dung samples found at ground nests, one with hostra rings, and a third was from dung not associated with a ground nest but with hostra rings). Fiber remains had been negligible in the dung washes prior to November 13. On several occasions at the end of and after the rainy season, extensive foraging remains left by chimpanzees in the river beds attested to the importance of Marantaceae herbs in the diet ­ on one occasion it looked to this observer more like the feeding remains of gorillas than chimpanzees (several large piles of stripped and chewed Megaphrynium and gonle herbs). Although Megaphrynium appears to have been foraged on opportunistically throughout the study period, larger quantities of all herbs, judging from feeding remain and dung wash evidence, appear to have been exploited towards the end of and after the rainy season. A much more diverse variety of fruit seeds was found in the dung past early November as well, the majority unknown except by Azande names (one staple food which did not, however, seem to vary in quantity in the dung and feeding remains between wet and dry seasons was the fruits of Afromomum, which were extremely common in dung samples throughout the study). One sample from the post-October time period contained 18% driver ant parts (found only in one other sample previously). To this date no evidence of predation on non-insect animal prey has been uncovered (what we thought to be a turtle finger bone turned out to be an oddly-shaped stick), although the trackers say that the Bili chimpanzees eat black and white colobus, duikers, turtles, and even fish.

To this date the chimpanzees have rarely been seen using the savannahs. However, according to the trackers, later in the dry season they will venture out to make use of several savannah fruits. We have already found the remains of one savannah fruit in a dung wash sample, and also filmed chimpanzee prints along the edge of the savannah.

We are as of yet unable to say if there is dietary specialization occurring between the ground-nesting chimpanzees and the tree-nesting ones (assuming that some of the chimpanzees are more likely than others to nest on the ground than sleep in the trees) ­ however, the relatively large proportion of the dung samples that were found in ground nests containing significant quantities of fiber hints at this possibility. Considering the large size of the dung of some of these individuals and their possible increased degree of terrestriality, it is hoped that more dung samples will allow us to directly answer the question.


33 dung and 5 hair samples have been collected as of 24 December for DNA analysis, from different areas across the study region. The majority of the samples were from nest sites and/or contact sites, and include dung and DNA samples from 6 ground nests (all from the Dikpai/Nambala region). Comparing these samples with those collected at the study site and from nearby areas over previous years will enable a good picture of the population genetics of the chimpanzees of the region to be constructed. Analysis of the samples will also tell us much about chimpanzee home range sizes in the area, which will be of practical use in the habituation process and also aid in assessments of numbers of chimpanzees in the North Central DRC.


Non-systematic data has been recorded for evidence of all large mammal species, including elephants, lions, hyaenas, pangolins, giant forest hog, and buffalo. A continuous data-base is maintained for where and when these animals were seen or heard. So far 32 elephant evidences have been recorded, most within the NW region of the study area (Dikpai/Nambala), ranging from a contact to dung samples collected for Dr. Sam Wasser (8samples). Leopards and hyaenas are heard regularly throughout the study region, and lions have been heard twice and footprints filmed once.


The chimpanzee population of the Camp Louis study area shows a suite of cultural and possibly physiological differences that may set it apart from all other populations of Pan troglodytes studied to date. The habituation of these chimpanzees will undoubtedly lead to many surprises and will possibly require us to rewrite the book on the species. We will learn why it is that at least some members of this population regularly build ground nests in a gorilla-like fashion, both in river-beds and in dry-ground forest, despite living in what is likely the most predator-rich habitat in which chimpanzees have yet been studied. This behaviour may be found to be linked to increased terrestriality in general, as well as larger body size and increased herbivory. Are we observing a sex difference: large, terrestrial, herbivorous males and smaller, arboreal, frugivorous females? Such a discovery would have important ramifications for hominid socioecology.

Although tantalizing evidence points in this direction, it is still too early to know for sure. Habituation will certainly reveal such sex-role-differentiation if it exists. In addition, there is the possibility of discovering unique adaptations for acquiring food, such as the use of large branches for ant-dipping, a new tool-type for breaking into bee hives, and techniques for the capture of fish and turtles (the latter three behaviours so far only described to us by the local trackers). Possible new types of symbolic communication may be documented. Looking at the bigger picture, knowledge of the demographics and population densities of chimpanzees in this savannah/forest mosaic will provide key information to help to determine the number of chimpanzees living in North Central and North Eastern DRC, information of crucial importance for the conservation of Pan troglodytes. Our continued research presence in the area will help give the local Azande people a reason to value the chimpanzees more alive than dead: already members of the local community, some of whom hunted the apes prior to the arrival of Karl Ammann, enjoy hearing stories of‘ Madam Caroline’ and seeing videos of our contacts. Despite the fact that the Azande have hunted chimpanzees near Bili in the recent past (and certainly still do in some areas), the relative isolation of the area and the lack of industrial logging and other extractive industries means that these chimpanzees are probably under less direct threat from human activities than in many other regions of Central Africa, thus enabling us to habituate the apes without exposing them to excessive risk. In addition to the long-term conservation efforts undertaken by Wasmoeth Wildlife Foundation and Karl Ammann, the presence of the University of Amsterdam and the expertise they have to offer will give the community something to be proud of, and lead to a collaboration which will offer benefits to all sides (except poachers!).


Below I have printed two recent forest narratives (daily detailed records of everything we see and hear) to try and convey a sense of the excitement of following and contacting the mystery apes:

Ph = pant-hoots
Td = tree-drums

December 18, 2004

At 2:35 and 2:50 we hear a leopard growl to the E, and then at 3:41 to the NW. At least I am pretty sure it was a leopard. Kittikawa is asleep and does not hear it. At 5:38 we hear phs and td to the N. At 5:41 we hear furious tds and phs VERY CLOSE to the N in the Nabilingba, and again at 5:42 and 5:44. At 5:48 and 5:52 we hear phs NE towards Nagiriso, which Kittikawa says is another individual. We leave camp at 5:52, and skirt the edge of Nabilingba on Kittikawa’s new trail (it slows us down a lot picking our way through the swamp in the dark). At 6:13 we hear phs and tds far to the N, and at 6:17 phs and tds to the N and NW. By now we have crossed the Nabilingba, and at 6:36 hear a td NE and then phs from mid-Licongo Trail. We reach the De tree at 7:08, and I sit and continue our 7 day stakeout while sending Kittikawa off to control along the river for nests/chimps. There are no chimps at the De but plenty of birds. At 7:20 I hear some movements from the swampy riverbed floor beneath the fig tree. By 7:21 I see the slender access tree beside the fig start to sway back and forth and I know what is coming! I raise the camera and see a big lanky grizzled-gray chimp ponderously climbing the access tree. The genitalia are not swollen but clearly female. She sits on a branch beside the De and by 00:10 camera time I am filming her backside as she sits. She is about 10 m off the ground (and the trip video camera should have filmed her as well before she began climbing). At 00:39 I get a great film of her climbing slowly and with difficulty into the fig tree, and it is now that I recognize her as the ancient female Caroline we contacted several hundred meters from here on Dec. 5 (CONT34) and probably also to the NW, CONTA8. I am positive from her movements, gaunt frame and hollow cheek bones and her general demeanor that this is the same individual.

Once again she appears to be alone. The film reveals that her belly, chest, and legs are a near-white grey color. She is a tall, bulky chimp but VERY feeble, and moves like Flo of Gombe did towards the end of her life. Caroline looks right towards me but does not appear to see me. She rests from her exertion on a branch, in a lying position, until 1:22 camera time when she picks her way over to another branch, settles down and begins eating figs (1:42 camera time). At this point only her arms are visible. The time of day is 7:23, and I decide the moment is ripe for a contact, so I begin clucking first (at 2:10 camera time). She does not react and continues feeding, so at 2:23 I lala ­ 7 seconds later she has stopped picking fruits and just sits there apparently watching me (I am very visible through a gap in the trees) until 3:29 camera time, when she moves out into the open on a branch, approx. 15 m elev., and watches me (it is now 7:26 am). 3 minutes later, at 6:31 camera time, the old female creeps over to the E to sit behind the main trunk of the fig tree, peeking out at me. I get some good shots of her face her ­ she has a long muzzle, gaunt cheeks, and is bald on top, with not much hair anywhere. I take a photo and at this time (7:26 - 7:29 camera time) she begins descending down a neighboring palm tree, very slowly. By 7:30 am (8:19 camera time) her movements are no longer visible, and the cotact ends. The contact lasted approx. 6.5 minutes (I lost a few seconds of camera time when I took the photo at the end). We go to see if the hidden video camera still works (it does) and then we go to the SE to find the chimp evidence Kittikawa has found in the Nabilingba Forest. Going S along the tangled edge of the Nabilingba on an elephant trail, we find: 2 piles of 1 month old elephant dung and a footprint (waypoint E23), and a bit S of this some Afromomum shoots that chimps ate yesterday, according to Kittikawa, at the same densely herbaceous spot where we find last night’s fibrousy giant forest hog dung (I save a DNA sample just in case Sam Wasser has any scientist friends interested in the genetics of this rare species). We follow the elephant trail S into very beautiful open forest that makes me feel as if I am in the primary forests of Mondika (Ndoki). Kittikawa starts a trail we will call Njoku, going S to intersect with Licongo near. We also find a huge Likuyo tree, not in fruit. 100 m S we find more 1 month old elephant dung. We get back to Camp Makassi by 13:15, and I tell Kittikawa his attitude was good today, if we can work together like this then there is no problem. He leaves quite cheerful. Sadly it is not to last.

Licongo arrives. I spend a pleasant evening chatting with him about his life (despite his youthful appearance he says he is 50 years old, that his mom used to bring him and his siblings to these very same forests to fish, and that he knew Ligada as a child here, and that that the forest been steadily replacing the savannah since those days, and that sadly everyone in his immediate family but one brother is now dead). I also listen to the enigmatic simbiliki munching away at the roots of the elephant grass in the savannah, and we hear buffalo bellowing at 20:45 in the grassland next to our camp.

December 19, 2004
At 5:29 we hear a hyeana calling to the NW. Licongo says he heard many chimps phing to the NW around 2 am (I slept soundly through this). We leave Camp Makassi at 6:18 heading NW. At 6:21 we hear a hyaena to our E. 6:47 ­ more phs NW, 6:56 ­ phs WNW. At 7:12 we contact red tailed guenons on Ligada just W of Licongo (thinking at first they are chimps). We sit for about 20 minutes on the S bank of the Nambala eating oranges, and then at 7:27 decide to head E to the fig tree of our last few contacts. But we have only gone 100 m or so when we hear a raucous chorus of phs at 7:31 very close to where we had been sitting, to the W or NW in the Nambala River. We cross the formidable ankle-deep Nambala as quickly as we can (never a pleasant experience, and it always slows us down considerably), and then we hear phs a little farther W in the river. We follow elephant tracks through the dense swampy tangle (seeing old dung) and at 7:44 hear phs and screams fairly close to our W.

7:46 ­ little hoots not far, in the trees. At 7:47 and 7:51 we hear more phs W, but it sounds like they are moving farther away ­ it becomes clear they are travelling along the ground. We reach solid ground and listen for a while, and hear nothing. So we move alongside the river SW hoping to run into the chimps that way (Licongo thinks we should recross the river and go back to the fig tree, but I want to try heading in the direction the big group of chimps is ­ at some point we are going to need to be able to follow them, and even predict where they are going). Approx. 300 m SW we find 2 saplings that have been snapped in two that Licongo says were broken off by displaying chimps the day before (and we will see this again further SW as well). At 8:47 we hear phs far to the W ­ they are clearly travelling. We encounter Ligada and Kongonyeses’ newly-cut trail (a continuation of Pandi) and discover a giant Likuyo tree with a few ripe fruits, jealously defended by one very aggressive red-tailed guenon! A big crop will soon be ready, and I think it will be a good idea for Ligada and Kongwonyese to stake it out for contacts while I am gone for New Year’s.

Licongo estimates chimps should be feeding at it in about a week. We have just found an approximately 2-day old nest site of 2 tree nests (2 and 2.5 m elevation) and I am struggling to get a GPS point when we hear a huge chorus of phs very close to our SW! We head speedily in that direction, passing by 2 more old tree nests, and at 9:40 hear more phs close SW. 9:40­ bark SW. At 9:44 we hear a ph SW, but now it is further off ­ they are still travelling. We arrive close to the edge of the Dikpai Savannah, and Licongo feels sure we have lost them. But I have a strong feeling that we might run into them following Pandi Trail S homewards. Not long afterwards my hunch proves right: At 10:06 I spot an adult chimp in the canopy about 50 m E of the trail. I pull Licongo over and show him, and we see more chimps in the towering (non-fruiting) gelo tree. We quickly move through fairly open forest towards the chimps. CONT39 begins when we see an immature chimp perched above us in a Kpai tree approx. 10 m W, 15 m elevation, and I begin to cluck and lala at 10:09 am (00:50 camera time). (There is an adult female, probably the mother, present in this tree as well, but we will not see her for another half hour or so). The immature is peering down at us, not panicking (I am turning the camera on and off during the contact to take video photos, so in this contact the camera time cannot be reliably used to track time. We will rely on my watch).

At 2:23 camera time, after much searching with the camera, I get the immature in frame and begin taking some pretty decent films and photos. On the film we can see big ears, a pale face, little pink genitals, and a white tail tuft ­ and a very sombre expression. At 3:01 camera time he or she screams at us, and knocks stuff down from the tree on us. At 10:13 am we see that there are other chimps in a big non-fruiting gelo tree about 40 m S (these were the chimps I first saw from the trail). I get another photo of the immature above us at 3:50 camera time and then, seeing he/she has assumed a more casual posture, I move towards Licongo approx. 15 m W. Licongo is pointing out the gelo tree-full of chimps approx. 40 m to our S. At 10:15 I film a subadult or young adult female with a pale face slowly start descending the gelo tree (4:27 ­ 4:37 camera time) ­ pale skin shows through her black body hair. She moves into another tree. Meanwhile, in the Kpai, the little one defecates. Back in the gelo, another adult chimp is briefly filmed moving into another tree to the E, and then a third adult moves from a tree close to above our head into the gelo and then runs down along that branch to the E…that’s a minimum of 3 in the gelo tree. At 10:17 we see the movements of more descending to the E. So far that is a minimum of 5 chimps: 3 in the Gelo tree and 2 in the Kpai (we will soon meet the mother), and probably more.

At 6:49 camera time I return my attention to the little one in the Kpai near us. I ignore my rule about not getting right under the chimps and crawl under the chimp, lie down on my back on the ground and film upwards, capturing some very good images of the chimp. I want the chimp to see that I am calm and lying down (this is at 10:19 am). At 7:45 camera time I am filming the immature ­ he/she seems relaxed and is still peering at me. Two decent photos are taken at 9:14 and 9:25 camera time. At 10:22 I pretend to sleep, putting the camera down (I am pushing down a sapling with my foot so the chimp can see me clearly ­ I think familiarity breeds boredom). There is no screaming, defecation, or displays ­ the little one is just watching (estimation: 3 years old). By 10:26 am the immature has moved to another branch, but still overhead. I pretend to sleep some more. At 10:31 he/she walks to the other side of the branch ­ more defecation around me (I will later collect this).

By 10:42 am I am filming the little chimp lying on his/her side resting! (photo 12:35 camera time). AT the same time I start hearing a chimp approx. 100 m S giving out hoarse screaming calls. The immature sits up when he or she hears the calls. 10:44 ­ several more hoarse cries S. Thinking this is the baby’s mother calling for him or her, I decide to move back to sit with Licongo 10 m W to give the baby some breathing room (this is at 10:47 am, and I have heard more screams S, maybe moving eastward). Indeed, we prepare to leave.

At 16:13 camera time I get a very good camera photo of the baby, and see the pink little vulva­ she is a female (see film). Then Licongo points out what will turn out to be an adult female (probably the baby’s mother) sitting partially hidden in the Kpai tree approx. 4 m to the baby’s W ­ she has clearly been there the whole time, quiet, watching us. We are 10 m away from the base of their tree. At 10:52 we hear another scream SE. On the film, we can see the adult female above us has moved a bit ­ all the fingers are present on her black right hand (no snare wounds). As the baby’s mom is with her, we decide we can safely stay without separating the baby from the group.

10:54 and 10:55 ­ screams far-ish (100 m?) SE. By 19:43 camera time the adult female moves towards us through the canopy until she is directly above our heads (this is good, I think!). I see her detuminescent female genitalia well ­ she appears to be somewhat skinny, grey-ish grizzled (I do not get her on film). At 19:49 camera time I get a very good video photo of the baby sitting above watching us with her chin on her knee! The adult female, who is now directly above us (both Licongo and I are lying together with our backs on the ground), then douses us with urine and faeces ­ I am covered! Then she continues NW, followed by the baby. The baby passes over us; the adult female, now approx. 10 m NW, screams, and the baby screams in response. They slowly start moving off to the NW through the canopy.

Then, a very strange thing happens, which I think is a very good sign. In the trees about 50 m to our SSW appears a small chimp, bigger than the immature we have just contacted but still with white face, big ears and I THINK a tail tuft. I think I am filming the whole thing but it turns out in my excitement I forget to press record ­ a shame. Over a 5 minute period, this screamer from the S slowly approaches us through the canopy to S and then around to the SE, and approaches us to within 10 m in a tree above our heads, staring down and screaming a or rather barking aggressively at us! A lot of aggression for such a tiny guy. I THINK this is the screamer from the S we kept hearing earlier in the contact. He or she stays close to us for about a minute and a half at 11:49, pounding on the branch and shrieking wraah barks at us (all I record is a blurry photo of him in aggressive action at 21:51 camera time) and then he or she passes directly over our heads to follow the adult female and smaller immature NW! This guy is acting like a naive Ndoki Forest chimp! I guess it is the new generation we will reach first.

Aggression is, I think, better than fear. We last hear this chimp urinating to NW at 11:51 about 30 m WNW, at which point we can roughly say the contact ends (although they probably stay within hearing distance for longer). Not bad, 102 minutes! I was also able to collect 2 dung samples, one which the adult female so obligingly deposited on top of us (she must know how much I like collecting DNA) and the other from where the baby defecated. The Kpai tree in which they were feeding measures 272 cm circum. We find many open Kpai shells and freshly-sucked on seeds. About 50 m S we find a De tree (smothering a Badu tree) at which it the chimps have also eaten today. 50 m S of this on Pandi Trail we find another fruiting De. This sure is a fruit-rich sector! Returning along Ligada Trail we find a half of a Buta fruit the chimps ate today. It looks like Landolphia a bit: this is the first time I have seen the fruit the seeds of which are so often in the dung.

From 12:50-12:55 we see and film a big group of black and white colobus in the trees just S of Karl X Ligada. Heading back to Camp Louis on Main Camp Trail we see buffalo tracks from this morning moving E across the savannah (just NW of Dkpito) and on savannah 3 we see buffalo tracks moving N from yesterday. As always, fresh warthog dung is found on savannah 2. Dido says he heard chimp phs to SSW of Camp Louis at 6 am.

NOTE: I have been away from Camp Louis since December 29, and two trackers who have been trained to use the video camera and GPS, Ligada and Kongwonyese, have been in charge of the chimpanzee work. They describe having had at least 5 contacts in the Nambala region, and claim they now recognize ­ and have named ­ two more younger individuals. I will be returning to Camp Louis on January 12.

Thurston Cleveland Hicks
7 January 2005