At
Bossou more than 200 plant species, representing approximately 30% of
available species in the habitat, are consumed by the chimpanzees, comprising
more than 246 plant parts (Sugiyama and Koman 1992). Yamakoshi (1998)
showed that Bossou chimpanzees spend approximately 60.7% of their feeding
time consuming fruit. Leaves and woody pith are the next two most important
foods for the chimpanzees at this site. Indeed, Bossou chimpanzees spend
about 10.8% and 10.1% respectively feeding on these two food items.
Seeds and the pith of herbaceous plants also comprise a non-negligible
portion of their diet. Takemoto (2002) also noted that cultivars comprise
6.4% of the annual diet of Bossou chimpanzees and are thus fully integrated
in their dietary repertoire, although their seasonal proportion in the
diet can fluctuate quite significantly (Yamakoshi, 1998). Bossou chimpanzees
also eat flowers, bark, roots and tubers, tree gum and insects; e.g.
adult termites (Isoptera) and ants (Dorylus spp. and Oecophylla
longinoda) and the eggs and larvae of ants, bees and several species
of beetle such as the Raphia coleopteran (Rhynchophorus quadrangulus).
Other food items consumed more infrequently include algae, mushrooms,
honey, bird eggs and mammals such as the tree pangolin (Phataginus
tricuspis). Hunting for animal prey at this site is relatively rare
compared to other sites where chimpanzees have been studied, probably
due to the paucity of other mammalian species in the habitat.
Yamakoshi (1998) showed that, when fruits are scarce, Bossou chimpanzees
effectively increase their tool-use activities, especially nut-cracking
and pestle pounding, in order to gain access to otherwise inaccessible
food resources and to boost their energy intake. In addition, during
such times of fruit scarcity, when food resources may be patchily distributed
and more rare, Takemoto (2000) demonstrated that Bossou chimpanzees
spend less time feeding and moving and decrease their dietary diversity.
Factors
affecting party size and composition at Bossou have been investigated.
Sakura (1991, 1994) founded that the pattern of party formation of the
Bossou chimpanzees is very similar to that observed in other populations
where influential factors influencing party size and composition include
food supply, presence of danger or predators, estrous females and infants.
However, Bossou chimpanzees differ from other communities in that they
tend to form more cohesive groups (Sugiyama and Koman, 1979a) and inter-female
relationships are highly affiliative when compared with those of the
Gombe and Mahale communities in Tanzania (Sugiyama, 1988). Furthermore,
male-male grooming frequency was found to be lower than that recorded
in the east African subspecies (P. t. schweinfurthii). The community
size at Bossou is not large and since 1976 the number of adult males
has been small. The Bossou community has atypical demographic features
and population dynamics, which can possibly be explained by its semi-isolation
from adjacent communities in the Nimba Mountains and its access to high
energy foods such as crops and oil-palms during periods of fruit scarcity.
The
Bossou chimpanzees display a large repertoire of tool-using behaviors,
some of which are unique to this community. Chimpanzees at Bossou
are well known for using a stone hammer and anvil to crack open
oil palm (Elaeis guineensis) nuts (Sugiyama and Koman, 1979b).
They have also been observed using leaves for drinking water, sticks
or stalks of vegetation to consume insects, honey or algae, and
petioles of the oil-palm tree as pestles to extract the heart of
the palm trunk.
Among all the tool-use behaviors observed in the wild, nut-cracking
is, probably the most sophisticated performed by chimpanzees in
the wild (Matsuzawa, 1994). In 1989, Sugiyama set up with the assistance
of T. Fushimi an outdoor field laboratory known as the "bureau"
at the top of a hill in the core range of the chimpanzees. Matsuzawa
and colleagues then started field experiments at the "bureau"
to gain more insight into nut-cracking behavior, by providing the
chimpanzees with stones and nuts (Sakura and Matsuzawa, 1991; Matsuzawa,
1991, 1994; Fushimi et al., 1991; Sugiyama et al., 1993b; Biro et
al., 2003). These longitudinal experimental field studies revealed
the ontogenetic development of stone tool-use and suggested the
existence of a critical learning period for acquisition, spanning
the ages of 3 to 5 years old. (Inoue-Nakamura and Matsuzawa, 1997).
Studies of tool-use have also focused on ant-dipping among Bossou
chimpanzees (Humle and Matsuzawa, 2002; Yamakoshi and Myowa-Yamakoshi,
2004). Observations suggest a strong influence of prey (Dorylus
spp.) characteristics, including aggressiveness and/or gregariousness,
on tool length and technique employed by the chimpanzees.
Extensive
surveys of communities adjacent to Bossou have shown that population-
specific details of tool use, such as the selection of species of
nuts as targets for cracking, cannot be explained purely on the
basis of ecological differences. Oil palm (Elaeis guineensis)
use for feeding purposes was investigated across the three chimpanzee
communities - Bossou and Séringbara in Guinea and Yealé
in Côte d'Ivoire (Humle and Matsuzawa, 2004). When comparing
the three sites, Bossou chimpanzees demonstrated the greatest frequency
of use of the oil palm, while Séringbara chimpanzees failed
so far to exhibit any uses and Yealé chimpanzees showed all
uses observed at Bossou excepting pestle pounding and mature leaf
pith-feeding. We found no clear difference in proximate environmental
variables underlying observed variations in use between the three
sites, yielding the conclusion that these differences are cultural.
Assuming individual interchange between these communities and the
involvement of social learning in the intra-community transmission
and maintenance of these uses, this result raises interesting questions
about diffusion of behavior between neighboring chimpanzee communities.
Matsuzawa and colleagues have been carrying out field experiments
on social transmission of behavior as an indirect approach to illuminate
key aspects of both cultural innovation and transmission between
neighboring communities of chimpanzees (Matsuzawa, 1994, 1996; Matsuzawa
et al., 2001; Biro et al., 2003). In the outdoor nut-cracking laboratory,
nuts of Coula edulis and Panda oleosa, normally unavailable
in the Bossou range, were provided and the reaction of the chimpanzees
observed. Responses of individuals toward the novel items differ
markedly with age, with juveniles being the most likely to explore.
Furthermore, subjects are highly specific in their selection of
conspecifics as models for observation, attending to the nut-cracking
activities of individuals in the same age group or older, but not
younger than themselves. Together with the phenomenon of intercommunity
migration, these results demonstrate a mechanism for the emergence
of culture in wild chimpanzees.
Chimpanzees
possess a broad and flexible repertoire of vocalizations (Goodall,
1986), composed by several variations of grunts, barks, screams
and hoots (Mitani, 1996), and which have as main function to express
emotions (Goodall, 1986). These vocalizations can be directed to
members of the community, members of neighbor communities or external
stimuli, as food or animals of other species (Goodall, 1986). Although
previous studies have demonstrated significant "regional"
variations in some vocalizations (Arcadi, 1996, Mitani, Hasegawa,
Gros-Louis, Marler & Byrne, 1992, Mitani, Hunley & Murdoch,
1999), a relatively small amount of data have been collected and
compared among different populations of wild chimpanzees. For that
reason, the vocal behavior of each particular community of chimpanzees
needs to be studied in details and be considered as unique in some
aspects. Short-distance and long-distance calls have been recorded
by Sousa (in prep.) in order to describe/determine the vocal repertoire
of Bossou chimpanzees and to understand how emotional state, individual
relationships, social context and age affect this acoustic signals.
The vocal recordings have been done using continuous recording method.
Whenever possible, the context within which the vocalization occurred,
the identity of the vocalizer and to whom it was directed were registered.
Two different methodologies have been used across the four one-month
periods of recording (2002 to 2006): 1) Recording of the vocal behavior
of the chimpanzees simultaneously with the video recording of the
tool-using sessions at the Bureau. 2) Recording of the vocal behavior
mainly by following a different focal animal every day. Although
each day a different focal individual/pair was followed, all vocalizations
emitted by other individuals in the vicinity were also recorded.
At the Bureau, the identification was done by direct observation
by Sousa, and when following the chimpanzees in the forest, it was
done with the help of the guides, who were able to identify the
individual by the vocalization. By another, the clear acoustic distinctiveness
existing among individuals of a same group (Marler and Hobbett,
1975, Mitani et al., 1996) will be studied and compared with the
results obtain through computer-mediated tasks in captive chimpanzees
(Martinez et al., in prep.).
Crop-raiding
by wildlife is one of a range of adaptations to a loss of natural
habitat allowing greater access to an array of energy-rich food.
Many non-human primate species have adapted their feeding repertoire
to include crop-raiding as part of their ecological strategy.
Chimpanzees bordering agricultural land and human settlements frequently
raid crops and can compete with humans over natural resources. Availability
of and fluctuations in wild forest foods may affect crop-raiding
levels, as particular crops might be crucial for chimpanzee subsistence,
while others are exploited because they are more palatable or nutritious
than wild foods.
The small home range (15 sq. km ) of the Pan troglodytes verus
community at Bossou is fragmented and surrounded by cultivated orchards,
fields and farms. During a 12-month study (2004-2005), all-occurrences
of crop-raiding events for simple-sugar fruits (papaya, banana,
orange, mandarin and pineapple combined) were noted. Transects through
the chimpanzees' core area were monitored to asses forest fruit
availability. The seasonality of cultivars was rated using questionnaires
on availability in respondents' farms.
Results show that chimpanzee crop-raiding increased when wild fruits
were scarce; cultivars act as fallback foods during periods of low
forest fruit availability. Adult males raided cultivars more often
than other age/sex classes, suggesting greater confidence, and crop-raiding
by adult male-only parties was additionally associated with increased
exposure and risk.
Effective management strategies to conserve the Bossou chimpanzees
require an in-depth understanding of their ecology; findings can
be extended to other great ape populations living in restricted
home ranges to mitigate risks of human-ape conflict.
(Hockings, Anderson and Matsuzawa, 2006, in preparation).
Little
information is available on the intestinal bacteria of chimpanzees
in the wild due to the technical difficulties of studying intestinal
bacteria in the field. In this study, molecular-based bacterial analysis
was performed to overcome this difficulty because PCR-based methods
such as temperature gradient gel electrophoresis (TGGE) and amplified
ribosomal DNA restriction analyses (ARDRA) of the bacterial 16S rRNA
gene can be applied to ethanol-fixed fecal samples. The common presence
of bacteria belonging to the Clostridium rRNA sub-group XIVa, such
as Ruminococcus obeum and Eubacterium sp., was indicated
for Bossou wild chimpanzees by ARDRA. TGGE on partial 16S rDNA followed
by hierarchical clustering analysis showed a systematic difference
in composition of intestinal microbiota between wild chimpanzees and
those in captivity. However, several TGGE bands commonly shared by
wild and captured chimpanzees were excised, and their sequences were
obtained. They were suggested to be the Clostridium leptum
subgroup bacteria, Lactobacillus gasseri-like bacterium, and
Bifidobacterium pseudocatenulatum- or B. catenulatum-like
bacterium. These may be considered as common intestinal bacteria for
chimpanzees and are possibly transmitted vertically over generations.(from
abstract Uenishi et al. 2006. Am. J. Primatol. in press)
The selective ingestion of plant gum exudates by chimpanzees has been
frequently observed at various study sites. At Bossou, Guinea, chimpanzees
also frequently ingest Albizia zygia gum exudate. A functional
explanation for this behavior is lacking, so we evaluated its possible
contribution of energy in the form of short-chain fatty acids (SCFA)
as well as minerals. An in vitro fermentation study of A. zygia
gum using the fecal bacteria of a Bossou chimpanzee showed that carboxylic
acids were produced with a 6-hr lag phase up to 44 mmol/l by 18 hr
of incubation. Acetate was the most abundant acid produced, followed
by lactate and propionate. The energy supplied from the fermentation
of a piece of gum exudate (20-30 g) was negligible in comparison with
the estimated daily energy requirements of chimpanzees in the wild.
However, A. zygia gum exudate (20-30 g) can supply sufficient
amounts of calcium, manganese, magnesium, and potassium to fulfill
the daily requirements for these minerals in chimpanzees. (from abstract:
Ushida et al, Am. J. Primatol. 68:143-151, 2006).
The
chimpanzee populations of the Bossou and Nimba regions in West Africa
were genetically surveyed to 1) reveal the genetic relationship between
the Bossou and Nimba populations, and 2) elucidate the evolutionary
relationship between the Bossou-Nimba and other West African populations.
The chimpanzee group at Bossou is characterized by its small population
size, no evidence of contact with neighboring populations, and no
female immigration. It is believed that most females and adolescent
males emigrate from this population. To reveal the genetic signature
of these characteristics, we examined the genetic diversity of Bossou
and two neighboring populations (Seringbara and Yeale) in the Nimba
Mountains by sequencing approximately 605 bp of the mitochondrial
DNA (mtDNA) control region. A total of 20 distinct mtDNA variants
were observed from 56 sequences of noninvasively collected, anonymous
samples. Nucleotide diversity in the Nimba Mountain populations was
0.03-0.04, and did not differ significantly from that in the Bossou
population. Very few mitochondrial variants are shared among the sites
sampled, which suggests that there is little gene flow involving mtDNA.
Nevertheless, no clear population structures were revealed in either
population. A comparison with published sequences from West African
chimpanzees (Pan troglodytes verus) indicates that the variants
observed in the Bossou and Nimba regions are scattered throughout
the subspecies, rather than clustered according to geographic region.
This suggests that the Bossou-Nimba populations derived only recently
from the common ancestral population of the West African chimpanzees,
and did not pass through a bottleneck. (from abstract: Shimada et
al., Am. J. Primatol. 64:261-275, 2004).
Surveys of wild chimpanzees in Nimba and neighboring sites : ecology, tool-use and conservation
1) Surveys in the Western part
of the Nimba Mountains Biosphere Reserve Sugiyama
visited Séringbara several times since 1976. He interviewed
the villagers, and conducted two surveys of the forest surrounding
the village in order to determine the presence of chimpanzees in the
area. He concluded that the chimpanzees were only seasonally transient
to the region (Sugiyama, 1981). However, over 70 nests and numerous
feeding remains of chimpanzees were discovered in 1999 in the forest
beside the village, while vocalizations of chimpanzees were regularly
heard (Shimada, 2000).
This was further confirmed during Matsuzawa's and colleagues' visit
to the Séringbara forest in January and February 2000 and Humle
visits to this site between June and September 2000 and June and September
2001, during which they recorded further evidence of chimpanzees in
the area, including nests, feeding remains and indications of tool
use (Humle and Matsuzawa, 2001). Many behaviors specific to the Nimba
chimpanzees such ground nesting have been reported by Matsuzawa and
Yamakoshi (1996). Sugiyama (1995a) was the first to report the occurrence
of ant-dipping for Dorylus ants in the Nimba Mountains. Since
2003, Humle and Koops (Koops et al, in press) have been carrying out
more systematic research at this site: their nesting surveys and progressive
habituation of the chimpanzees suggest the presence of two chimpanzee
communities in the Séringbara area. Further research and consequent
habituation of the chimpanzees will confirm exact numbers and group
composition. Nesting patterns and characteristics of the chimpanzees
in the Séringbara region of the Nimba Mountains were investigated
in depth and across seasons (Koops, 2005 ) The effects of ecological
(i.e., fruit availability, habitat type) and topographical (i.e.,
altitude) factors on nesting patterns were addressed. Moreover, Koops
assessed whether nesting sites concur with sites of feeding activity,
and whether there exists seasonal variation in nesting patterns and
characteristics. In addition, ground-nesting behavior of the Nimba
chimpanzees has been specifically investigated (Koops et al, in press).
Koops examined the environmental and social factors that may account
for the occurrence and distribution of ground-nesting in Nimba. The
effects of season, altitude, slope and nesting tree availability on
the proportion of nests constructed on the ground were explored. The
occurrence of ground nests was found not to be affected by these basic
environmental factors, and social or cultural factors may provide
a more likely explanation for ground-nesting behavior in the Nimba
chimpanzees.
2) Surveys in the Eastern part of the Nimba
Mountains Biosphere Reserve Presence
of the western sub species of chimpanzee in the Nimba Mountains core
area has been reported since the late 1930s (Lamotte, 1942 and Holas,
1952). In 1941, the Nimba area has been classified as a natural reserve
to protect his highly endemic biodiversity and favoured its scientific
exploration, but no specific study has focused on chimpanzees until
the arrival of Sugiyama to Bossou in 1976.
Sugiyama visited the Gouela area in 1991. He saw chimpanzees, studied
their nests and confirmed presence of ant-dipping (Sugiyama et al.,
1995). In 1999, Shimada surveyed this area again and further confirmed
chimpanzee presence (Shimada, 2000). Nevertheless, little information
is available on the chimpanzees presently populating this huge mountainous
reserved area and some places have not been surveyed at all.
In March and April 2006, Granier conducted two surveys in the Eastern
part of the Nimba Mountains Biosphere Reserve, to assess the actual
ecological and conservational status of wild chimpanzee populations
(Granier, preliminary report).
The first survey was carried out in the forested south foothills of
the mountain range lying between Gouéla and N'Zo (sub-prefecture
of N'Zo). Globally, the forest is well preserved in this area and
seems to be healthy. No villagers are cultivating inside of the Reserve's
limits. Although there is a real problem of poaching, as indicated
by the numerous traps, cartridges and hunters encountered in the core
area of the reserve, daily observations of many various chimpanzee
tracks have permit to confirm the species' presence in this side of
the Nimba Mountains.
The second survey was carried out in the Déré forest.
A very critical general situation has been observed in terms of conservation
and local politics. Firstly, scares of logging are deeply visible
in this forest, which is now colonized by local people for intensive
cultivation and subsistence hunting. Even if good quality patches
of primary forest can still be found, the fragmentation is so high
that its consequences on ecosystems are really critical. Little scientific
data is available on the Déré reserved area, and no
study has been conducted concerning specifically chimpanzees. Only
one chimpanzee track consisting in a very old nest was observed in
13 days of survey.
3) Surveys in the Diecké
forest
The two study sites, which we have surveyed thus far, are located
beside two villages: Yossono (west of the reserve) and Nonah (east
of the reserve). It still remains undetermined as to how many chimpanzees
inhabit this reserve and how many communities pervade in the area
(Matsuzawa et al., 1999). But some preliminary behavioral data have
emerged, especially concerning tool-use at those sites (cf. Humle
and Matsuzawa, 2001). There were recent reports of hunting of chimpanzees
in the Yossono area dating back to July 2001, while hunting pressure
at Nonah does not appear to be as high. But hunting seems to be a
huge problem within this reserve and may pose a considerable threat
to the chimpanzee populations living in that region.
At the moment Diecké Forest is divided in 3 levels of protection
and 30 parcels, by a national project of conservation/reforestation,
damage minimization and regional development (Progerfor). The "série
d`amelioration" level correspond to a peripheral area, where
we can find forest fragments of slash-and-burn agriculture, for the
most part to cultivate rice fields and plant oil palm trees and secondary
forest mixed with altered primary forest. Then we have "série
d`utilisation durable", mostly altered primary forest and secondary
forest and finally the "série de protection integral",
the core of Diecké Forest, formed mainly by closed canopy,
extensive patches of rain forest, and this is the best preserved part
of the original forest (parcels 10 to 15). This heart of Diecké
forest is still largely unknown. In
2006 Carvalho continued survey in this area. KUPRI combining archaeological
and primatological methods; new zones were surveyed (achieving parcels
11 and 15) and local work teams were organized to set temporary camps
in the forest. The main goal, besides searching these chimpanzee communities,
was to find new nut-cracking places and register the entire tool-use
process in order to understand tool technology. KUPRI carried out
3 trips in Diecké Forest between January and April (mainly
during dry season) and set 2 temporary camps, one in Nonah area and
another in Korohouan area.
In Diecké forest we found 5 new nut-cracking places (of Panda
oleosa and Coula edulis). Places of Coula edulis
are the first ones to be found in Diecké forest area with this
nut specie. Between trips one place had been used by the chimpanzees.
We also found fresh traces of chimpanzee's passage, feeding and sleeping,
especially in Korohouan area.
Although human activities and hunting pressure are present and they
continue to damage and transform the natural forest habitat as we
could verify in 2006.
At
Bossou more than 200 plant species, representing approximately 30% of
available species in the habitat, are consumed by the chimpanzees, comprising
more than 246 plant parts (Sugiyama and Koman 1992). Yamakoshi (1998)
showed that Bossou chimpanzees spend approximately 60.7% of their feeding
time consuming fruit. Leaves and woody pith are the next two most important
foods for the chimpanzees at this site. Indeed, Bossou chimpanzees spend
about 10.8% and 10.1% respectively feeding on these two food items.
Seeds and the pith of herbaceous plants also comprise a non-negligible
portion of their diet. Takemoto (2002) also noted that cultivars comprise
6.4% of the annual diet of Bossou chimpanzees and are thus fully integrated
in their dietary repertoire, although their seasonal proportion in the
diet can fluctuate quite significantly (Yamakoshi, 1998). Bossou chimpanzees
also eat flowers, bark, roots and tubers, tree gum and insects; e.g.
adult termites (Isoptera) and ants (Dorylus spp. and Oecophylla
longinoda) and the eggs and larvae of ants, bees and several species
of beetle such as the Raphia coleopteran (Rhynchophorus quadrangulus).
Other food items consumed more infrequently include algae, mushrooms,
honey, bird eggs and mammals such as the tree pangolin (Phataginus
tricuspis). Hunting for animal prey at this site is relatively rare
compared to other sites where chimpanzees have been studied, probably
due to the paucity of other mammalian species in the habitat. 
Factors
affecting party size and composition at Bossou have been investigated.
Sakura (1991, 1994) founded that the pattern of party formation of the
Bossou chimpanzees is very similar to that observed in other populations
where influential factors influencing party size and composition include
food supply, presence of danger or predators, estrous females and infants.
The
Bossou chimpanzees display a large repertoire of tool-using behaviors,
some of which are unique to this community. Chimpanzees at Bossou
are well known for using a stone hammer and anvil to crack open
oil palm (Elaeis guineensis) nuts (Sugiyama and Koman, 1979b).
They have also been observed using leaves for drinking water, sticks
or stalks of vegetation to consume insects, honey or algae, and
petioles of the oil-palm tree as pestles to extract the heart of
the palm trunk. 
Extensive
surveys of communities adjacent to Bossou have shown that population-
specific details of tool use, such as the selection of species of
nuts as targets for cracking, cannot be explained purely on the
basis of ecological differences. Oil palm (Elaeis guineensis)
use for feeding purposes was investigated across the three chimpanzee
communities - Bossou and Séringbara in Guinea and Yealé
in Côte d'Ivoire (Humle and Matsuzawa, 2004). When comparing
the three sites, Bossou chimpanzees demonstrated the greatest frequency
of use of the oil palm, while Séringbara chimpanzees failed
so far to exhibit any uses and Yealé chimpanzees showed all
uses observed at Bossou excepting pestle pounding and mature leaf
pith-feeding. We found no clear difference in proximate environmental
variables underlying observed variations in use between the three
sites, yielding the conclusion that these differences are cultural.
Assuming individual interchange between these communities and the
involvement of social learning in the intra-community transmission
and maintenance of these uses, this result raises interesting questions
about diffusion of behavior between neighboring chimpanzee communities.
Chimpanzees
possess a broad and flexible repertoire of vocalizations (Goodall,
1986), composed by several variations of grunts, barks, screams
and hoots (Mitani, 1996), and which have as main function to express
emotions (Goodall, 1986). These vocalizations can be directed to
members of the community, members of neighbor communities or external
stimuli, as food or animals of other species (Goodall, 1986). Although
previous studies have demonstrated significant "regional"
variations in some vocalizations (Arcadi, 1996, Mitani, Hasegawa,
Gros-Louis, Marler & Byrne, 1992, Mitani, Hunley & Murdoch,
1999), a relatively small amount of data have been collected and
compared among different populations of wild chimpanzees. For that
reason, the vocal behavior of each particular community of chimpanzees
needs to be studied in details and be considered as unique in some
aspects. Short-distance and long-distance calls have been recorded
by Sousa (in prep.) in order to describe/determine the vocal repertoire
of Bossou chimpanzees and to understand how emotional state, individual
relationships, social context and age affect this acoustic signals.
The vocal recordings have been done using continuous recording method.
Whenever possible, the context within which the vocalization occurred,
the identity of the vocalizer and to whom it was directed were registered.
Two different methodologies have been used across the four one-month
periods of recording (2002 to 2006): 1) Recording of the vocal behavior
of the chimpanzees simultaneously with the video recording of the
tool-using sessions at the Bureau. 2) Recording of the vocal behavior
mainly by following a different focal animal every day. Although
each day a different focal individual/pair was followed, all vocalizations
emitted by other individuals in the vicinity were also recorded.
At the Bureau, the identification was done by direct observation
by Sousa, and when following the chimpanzees in the forest, it was
done with the help of the guides, who were able to identify the
individual by the vocalization. By another, the clear acoustic distinctiveness
existing among individuals of a same group (Marler and Hobbett,
1975, Mitani et al., 1996) will be studied and compared with the
results obtain through computer-mediated tasks in captive chimpanzees
(Martinez et al., in prep.).
Crop-raiding
by wildlife is one of a range of adaptations to a loss of natural
habitat allowing greater access to an array of energy-rich food.
Many non-human primate species have adapted their feeding repertoire
to include crop-raiding as part of their ecological strategy. 
Little
information is available on the intestinal bacteria of chimpanzees
in the wild due to the technical difficulties of studying intestinal
bacteria in the field. In this study, molecular-based bacterial analysis
was performed to overcome this difficulty because PCR-based methods
such as temperature gradient gel electrophoresis (TGGE) and amplified
ribosomal DNA restriction analyses (ARDRA) of the bacterial 16S rRNA
gene can be applied to ethanol-fixed fecal samples. The common presence
of bacteria belonging to the Clostridium rRNA sub-group XIVa, such
as Ruminococcus obeum and Eubacterium sp., was indicated
for Bossou wild chimpanzees by ARDRA. TGGE on partial 16S rDNA followed
by hierarchical clustering analysis showed a systematic difference
in composition of intestinal microbiota between wild chimpanzees and
those in captivity. However, several TGGE bands commonly shared by
wild and captured chimpanzees were excised, and their sequences were
obtained. They were suggested to be the Clostridium leptum
subgroup bacteria, Lactobacillus gasseri-like bacterium, and
Bifidobacterium pseudocatenulatum- or B. catenulatum-like
bacterium. These may be considered as common intestinal bacteria for
chimpanzees and are possibly transmitted vertically over generations.(from
abstract Uenishi et al. 2006. Am. J. Primatol. in press)
The
chimpanzee populations of the Bossou and Nimba regions in West Africa
were genetically surveyed to 1) reveal the genetic relationship between
the Bossou and Nimba populations, and 2) elucidate the evolutionary
relationship between the Bossou-Nimba and other West African populations.
The chimpanzee group at Bossou is characterized by its small population
size, no evidence of contact with neighboring populations, and no
female immigration. It is believed that most females and adolescent
males emigrate from this population. To reveal the genetic signature
of these characteristics, we examined the genetic diversity of Bossou
and two neighboring populations (Seringbara and Yeale) in the Nimba
Mountains by sequencing approximately 605 bp of the mitochondrial
DNA (mtDNA) control region. A total of 20 distinct mtDNA variants
were observed from 56 sequences of noninvasively collected, anonymous
samples. Nucleotide diversity in the Nimba Mountain populations was
0.03-0.04, and did not differ significantly from that in the Bossou
population. Very few mitochondrial variants are shared among the sites
sampled, which suggests that there is little gene flow involving mtDNA.
Nevertheless, no clear population structures were revealed in either
population. A comparison with published sequences from West African
chimpanzees (Pan troglodytes verus) indicates that the variants
observed in the Bossou and Nimba regions are scattered throughout
the subspecies, rather than clustered according to geographic region.
This suggests that the Bossou-Nimba populations derived only recently
from the common ancestral population of the West African chimpanzees,
and did not pass through a bottleneck. (from abstract: Shimada et
al., Am. J. Primatol. 64:261-275, 2004).
Sugiyama
visited Séringbara several times since 1976. He interviewed
the villagers, and conducted two surveys of the forest surrounding
the village in order to determine the presence of chimpanzees in the
area. He concluded that the chimpanzees were only seasonally transient
to the region (Sugiyama, 1981). However, over 70 nests and numerous
feeding remains of chimpanzees were discovered in 1999 in the forest
beside the village, while vocalizations of chimpanzees were regularly
heard (Shimada, 2000). 
Presence
of the western sub species of chimpanzee in the Nimba Mountains core
area has been reported since the late 1930s (Lamotte, 1942 and Holas,
1952). In 1941, the Nimba area has been classified as a natural reserve
to protect his highly endemic biodiversity and favoured its scientific
exploration, but no specific study has focused on chimpanzees until
the arrival of Sugiyama to Bossou in 1976. 
In
2006 Carvalho continued survey in this area. KUPRI combining archaeological
and primatological methods; new zones were surveyed (achieving parcels
11 and 15) and local work teams were organized to set temporary camps
in the forest. The main goal, besides searching these chimpanzee communities,
was to find new nut-cracking places and register the entire tool-use
process in order to understand tool technology. KUPRI carried out
3 trips in Diecké Forest between January and April (mainly
during dry season) and set 2 temporary camps, one in Nonah area and
another in Korohouan area. 