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Naïve Encounters with Chimpanzees in the Goualougo Triangle, Republic of Congo

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We describe the behavior of an unhabituated population of chimpanzees in the Goualougo Triangle, Republic of Congo. We encountered chimpanzee parties on 218 occasions during two field seasons (February 1999–December 1999, June 2000–June 2001). Overall contact rate was 0.63 contacts per day in the field (n = 347). During the first 5 min of observation, we recorded individual responses as curious, ignore, hide, or depart. In contrast to other unhabituated chimpanzees, curiosity was the most common response (84%) of individuals in the Goualougo Triangle. However, the responses were deeply integrated in the group's reaction to our arrival and behavior throughout an encounter. Based on the behavior of the majority of individuals in a group, we categorized entire contact events as nave, ignore, nervous, or depart. Nave contacts accounted for 69% of all encounters. Other contacts types occurred much less frequently: nervous (12%), depart (11%), ignore (8%). Nave contacts were characterized by chimpanzees that continued to exhibit curiosity throughout the encounter, the arrival of other individuals at the contact location, and relatively prolonged contact with observers (average duration: 136 min). It is likely that the high frequency of curious responses and nave contacts are due to the remote location of the Goualougo Triangle and the chimpanzees's lack of experience with humans. Documentation of this nave phenomenon has been successfully used to lobby for the protection of the chimpanzees and their habitat.
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International Journal of Primatology, Vol. 24, No. 2, April 2003 (
C°
2003)
Na
¨
ıve Encounters With Chimpanzees
in the Goualougo Triangle, Republic of Congo
Dave Morgan
1,3
and Crickette Sanz
2
Received November 5, 2001; revised June 6, 2002
We describe the behavior of an unhabituated population of chimpanzees in the
Goualougo Triangle, Republic of Congo. We encountered chimpanzee parties
on 218 occasions during two field seasons (February 1999–December 1999,
June 2000–June 2001). Overall contact rate was 0.63 contacts per day in the
field (n = 347). During the first 5 min of observation, we recorded individual
responses as curious, ignore, hide, or depart. In contrast to other unhabituated
chimpanzees, curiosity was the most common response (84%) of individuals
in the Goualougo Triangle. However, the responses were deeply integrated
in the group’s reaction to our arrival and behavior throughout an encounter.
Based on the behavior of the majority of individuals in a group, we catego-
rized entire contact events as na
¨
ıve, ignore, nervous, or depart. Na
¨
ıve contacts
accounted for 69% of all encounters. Other contacts types occurred much less
frequently: nervous (12%), depart (11%), ignore (8%). Na
¨
ıve contacts were
characterized by chimpanzees that continued to exhibit curiosity throughout
the encounter, the arrival of other individuals at the contact location, and
relatively prolonged contact with observers (average duration: 136 min). It
is likely that the high frequency of curious responses and na
¨
ıve contacts are
due to the remote location of the Goualougo Triangle and the chimpanzees’s
lack of experience with humans. Documentation of this na
¨
ıve phenomenon
has been successfully used to lobby for the protection of the chimpanzees and
their habitat.
KEY WORDS: Pan troglodytes troglodytes; chimpanzee; curious; na¨ıve.
1
Wildlife Conservation Society, Republic of Congo.
2
Washington University, St. Louis.
3
To whom correspondence should be addressed at 1431 Island Dr. S., St. Petersburg, Florida
33707; e-mail: goualougo@uuplus.com.
369
0164-0291/03/0400-0369/0
C
°
2003 Plenum Publishing Corporation
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370 Morgan and Sanz
With the goal of directly observing the full repertoire of chimpanzee
behavior, researchers at various field sites have dedicated many resources
toward achieving habituation: the acceptance by wild animals of a human ob-
server as a neutral elementin their environment (Tutin and Fernandez,1991).
In general, chimpanzees have been difficult to habituate unless provisioned
or patiently followed for several years. As a result, only several chimpanzee
communities have been successfully habituated: Gombe Stream National
Park (Goodall, 1986); Mahale Mountains National Park (Nishida, 1990),
Kibale Forest National Park (Wrangham et al., 1996), Budongo Forest Re-
serve (Reynolds, 1992), Tai National Park (Boesch and Achermann-Boesch,
2000); and Bossou (Sugiyama, 1981). All of them are located in eastern or
western Africa and represent only 2 of the 4 subspecies of chimpanzee: Pan
troglodytes schweinfurthii and Pan troglodytes verus.
Currently, there are no habituated communities of Pan troglodytes
troglodytes, which live in central Africa. Research on the central subspecies
has been limited to surveys of indirect evidence—nests, feeding signs, fe-
ces, tracks—and occasional observations of unidentified individuals (Fay
and Carroll, 1992; Garcia and Mba, 1997; Gonder et al., 1997; Idani, 1994;
Ihobe, 1993, 1995; Kuroda et al., 1996; Moutsambote et al., 1994; Nishihara,
1995/1996; Tutin and Fernandez, 1984, 1985, 1993a,b; Tutin et al., 1994;
White and Tutin, 2001; Yamagiwa et al., 1995). Attempts have been made
to habituate chimpanzee communities in central Africa by Nishihara (1995/
1996) and Tutin and Fernandez (1991). Tutin and Fernandez (1991) doc-
umented the behavioral responses of chimpanzees to humans in the Lop ´e
Reserve, Gabon. The most common responses were immediate departure by
flight, approach/wait for another before moving away from the observer, and
stealthy retreat. They very rarely exhibited hide, ignore, charge, or curiosity.
Researchers at Guga in the Ndoki Forests of the Republic of Congo suc-
ceeded in directly observating chimpanzees, but a community was never ha-
bituated during their 7-year research presence (Nishihara, 1995/1996). Due
to paucity of data from direct observation of Pan troglodytes troglodytes,
the expansion of mechanized logging, and the effects of rapidly increasing
human populations, it became a priority to identify a site in central Africa
where chimpanzee research was feasible.
In February 1999, a study site was established in the Goualougo Tri-
angle, Republic of Congo. Initial survey teams reported that chimpanzees
there did not immediately flee at the approach of humans, the most common
response of unhabituated chimpanzees (Fay, 1993). Instead of retreating, the
chimpanzees responded to the arrival of human observers with curiosity and
interest. Blake (1995) and Fay (1993) labeled the behavior na¨ıve. It is proba-
bly restricted to individuals with very limited exposure to humans. Due to the
remote location of the Goualougo Triangle, the chimpanzee population and
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Na
¨
ıve Encounters With Chimpanzees 371
their habitat have remained undisturbed. The Ndoki and Goualougo Rivers
form the western and eastern borders of the Goualougo Triangle. Their flood-
plains are dominated by swamps that may have formed geographical barriers
to human encroachment. We documented the chimpanzees’s responses to
our presence and its implications for conservation efforts in the region.
STUDY SITE & METHODS
Study Site
The Goualougo Triangle is located within the Nouabal´e-Ndoki Na-
tional Park (2
05
0
–16
56
0
N; 3
03
0
–16
51
0
E), Republic of Congo (Fig. 1). The
study area covers 30,000 ha of lowland forest and altitudes range between
330 and 600 m. Four habitat types occur in the Goualougo Triangle: mon-
odominant Gilbertiodendron forest, Gilbertiodendron mixed species forest,
mixed species forest, and swamp forest (Fay, 1993, 1997; Kuroda et al., 1996;
Moutsambote, et al., 1994).
The climate is transitional between the Congo-equatorial and subequa-
torial climatic zones (White, 1983). Rainfall is bimodal with a main rainy
season from August through November and a short rainy season in May.
Average monthly rain fall and temperatures at Mbeli Bai base camp, Re-
public of Congo, 17 km from the study area, are 1,710.9 mm (Stokes, 2000)
and 21.1
C (minimum) and 26.5
C (maximum). There is little seasonal vari-
ation it temperature (Stokes, 2000).
Methods
Chimpanzee Detection and Contact Protocol
We used 4 methods to locate chimpanzees: mimicking duiker calls to
attract them, hearing their vocalizations or buttress drumming, opportunis-
tic encounters, or conducting vigils of fruiting trees. We most frequently
located chimpanzees by approaching vocalizing groups or by opportunistic
encounters while walking through the forest. Encounters or contact events
involved the direct observation of 1 chimpanzee. During all contacts, ob-
servers minimized disturbance to the chimpanzees by immediately sitting
down and remaining quiet. Throughout the contact, chimpanzees dictated
the proximity to the stationary human observers by either moving closer
or retreating. Time of day, environmental conditions, or detection of other
groups occasionally prompted the observers to end contact.
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372 Morgan and Sanz
Data Collection Protocols
During the first 5 min of observation, we recorded individual responses
as curious, ignore, hide, or depart (Table I). We did not recognize the vo-
calization categories defined by Tutin and Fernandez (1991) as independent
responses, but instead as components of other categories. We collapsed ap-
proach/wait for another, avoid, flight, and stealthy retreat into a single cat-
egory: depart. We observed no change.
Fig. 1. Goualougo Triangle study site.
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Na
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Table I. Individual response categories (adopted from Tutin and Fernandez, 1991)
Curious Individual response includes 2 of the following elements: staring, head
swaying, crouching to get a better view of human observers, moving
closer to observers, slapping tree trunk to elicit response, inquisitive
vocalizations, following observers as they depart.
Ignore No discernable response shown. After noticing an observer, individual
continues with previous activity.
Hide Individual departs from view, but remains at contact location. We
occasionally see individual peering toward us through thick vegetation.
Depart After detecting human observers, individual leaves contact location. This
definition incorporates all departure categories defined by Tutin and
Fernandez (1991).
We categorized entire contacts as na¨ıve, ignore, nervous, or immedi-
ate departure (Table II). Although chimpanzees may have shown different
behaviors, the classification is based on the behavior of the majority of
individuals.
We collected the following data during each contact: method of location;
contact location (forest type, location in canopy or on ground); age-sex class
per Goodall (1986) of all individuals; party size; party type per Doran (1997);
overall contact duration. We identified individual chimpanzees via detailed
documentation (sketches and video recorded images) of distinctive physical
characteristics (Morgan, 1999). A spotting scope (Bausch and Lomb 15-
45 × 60) aided in viewing the physical features of distant chimpanzees.
Table II. Contact type categories
Na¨ıve After initial response, the majority of chimpanzees present at
a contact show continued curiosity toward human observers
(as indicated by exhibiting curious behaviors: (Table I).
After a period of intense interest, chimpanzees may return
to previous activities while monitoring human observers
(For example, chimpanzee may build a day nest and then
watch human observers while resting).
Ignore Throughout the contact, chimpanzees show no discernible
interest in observers. After noticing arrival of observers,
chimpanzees continue with their previous activities.
Nervous Chimpanzees retreat from observers by moving higher in
canopy or hiding behind vegetation. Chimpanzees alternate
attention between monitoring observers and other
chimpanzees in the party. Other indications of nervousness
include pilo-erection, self-scratching, and loose stool.
Immediate departure All chimpanzees immediately depart after becoming aware of
human presence. Same as depart category for individual
response.
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374 Morgan and Sanz
Data Analyses
To allow intersite comparisons, we present individual responses in the
same format as Tutin and Fernandez (1991) and Johns (1996). However,
we conducted no statistical analysis on the individual responses because
our study showed that data within each cell were not independent. Based
on repeated contacts of known individuals, individual chimpanzees were
represented more than once in a single cell.
Contact types aptly depicted the behavior exhibited by groups of chim-
panzees in the Goualougo Triangle to the arrival of our research team. Al-
though the same individuals were present at several contacts, we treated
contact events between different groups of chimpanzees on different days
as independent data points. We used Chi-square and Kruskal Wallis tests to
evaluate the relationship between contact categories and other variables.
RESULTS
We collected data during 347 days in 2 field seasons (February 1999–
December 1999, June 2000–June 2001). We have total of 365 h of direct obser-
vations during 218 chimpanzee contacts. Overall encounter rate is 0.63 con-
tacts per field day. We contacted chimpanzees most frequently by following
vocalizations and buttress drumming to the source (56% of contacts). Other
means of locating chimpanzees include opportunistic encounters (34%), vig-
ils of fruiting trees (8%) and mimicking duiker calls (1.4%).
Initial Responses and Contact Types
The most frequent individual response was curiosity and the most com-
mon contact type was na¨ıve. Table III has the overall relative frequencies
of individual responses by age-sex class. Curious responses were shown by
84% of individuals, and chimpanzees in each age-sex class are represented.
Table III. Individual response to human observers
Adult Subadult Juvenile
Response Male Female Male Female Male Female Infant Unk. Total
Curiosity 266 278 56 38 41 45 177 49 950
Ignore 12 19 2 3 3 1 11 5 56
Hide 9 26 0 3 3 7 24 14 86
Depart 3 5 0 1 1 0 5 24 39
290 328 58 45 48 53 217 92 1131
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Na
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Table IV. Comparison of individual responses among field sites
Lop´e Reserve Kibale Forest Goualougo Triangle
Individual response (n = 153) (n = 436) (n = 1131)
Curiosity 1% 6.70% 84.00%
Ignore 3% 25.80% 4.95%
Hide 5% 6.90% 7.60%
Depart 74% 35.6% 3.45%
Flight 39% 25.50% 1.41%
Stealthy retreat 10% 9.60% 2.03%
Approach/wait for another 25% 0.50%
Charge 1% 13.10%
Loud vocalizations 8% 7.10% n/a
Soft vocalizations 8% 4.80% n/a
In Table IV we compare our results with chimpanzee responses in Lop ´e
Reserve (Tutin and Fernandez, 1991) and Kibale Forest (Johns, 1996). In
Goualougo, na¨ıve contacts accounted for 69% of all encounters (Table V).
Other contacts types occurred much less frequently: nervous (11%), depart
(11%), ignore (8%).
Individual Identification and Repeated Contacts
We have identified 152 individual chimpanzees in the Goualougo Tri-
angle study area. The average number of contacts for each individual is 3.63
± 4.04 (range = 1–21). Ninety-eight percent of known individuals have par-
ticipated in 1 na¨ıve contact. Some individuals have continued to exhibit
curious behaviors after >20 contacts with human observers.
Table V. Duration of contacts ended by chimpanzees and humans
Proportion of Average
Contact type total contacts duration SD
Chimpanzees end (n = 118)
Na¨ıve 29% 2 hr 16 min 1 hr 38 min
Ignore 6% 2 hr 22 min 2 hr 15 min
Nervous 7% 42 min 37 min
Depart 11% 2 min 1 min
54% 1hr37min 1hr44min
Humans end (n = 100)
Na¨ıve 40% 1 hr 55 min 1 hr 25 min
Ignore 2% 35 min 12 min
Nervous 4% 38 min 40 min
Depart 0
46% 1hr45min 1hr24min
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376 Morgan and Sanz
Contact Location
As indicated by contact locations, chimpanzees showed a signifi-
cant preference for certain forest types (χ
2
= 180.48, df = 2, p < 0.01).
Chimpanzees occurred most often in mixed species forest (76%) and much
less frequently in Gilbertiodendron mixed species forest (14%) and Gilber-
tiodendron forest (10%). We never contacted chimpanzees in swamps. Forest
type is not significantly related to contact type (χ
2
= 0.88, df = 3, NS).
We contacted chimpanzees more often in the canopy (67%) than on
the ground (33%). When contacted on the ground, chimpanzees were twice
as likely to immediately depart than when contacted in the canopy. During
49.5% of all contacts, chimpanzees were observed descending to the ground.
They were most likely to descend to the ground during na¨ıve contacts and
least likely during nervous contacts.
Party Size and Composition
Average initial party size is 3.22 ± 2.07 chimpanzees (n = 218, range =
1 to 14). There is a significant difference between party size distributions
among contact types (Kruskal-Wallis, H = 29.21, df = 3, p < 0.01; (Fig. 2)).
Small initial party sizes are associated with immediate departures, and large
initial party sizes are associated with na¨ıve contacts. The small party size
reflects the large proportion of lone individuals that immediately departed.
Large party sizes are related to the relatively high proportion of mixed parties
associated with na¨ıve contacts (Fig. 2).
During 74 contacts, party size increased. Most of the increases (95%)
occurred during na¨ıve contacts. For na¨ıve contacts in which party size in-
creased, the average number of new arrivals is 6 ± 4.15 chimpanzees (n =
70, range = 1 to 18). Average total party size for other contact types is sim-
ilar to initial party size. Increases in party size are significantly related to
contact type (χ
2
= 34.40, df = 3, p < 0.01). Table VI shows average initial
party size, number of new arrivals, and total party size among contact types.
Contact Duration
The average duration of contacts is 100 ± 95 minutes (n = 218). In
Table V, we compare duration of contacts ended by chimpanzees and hu-
mans by contact type. Duration of contacts ended by chimpanzees is related
to contact type (Kruskal-Wallis, H = 66.64, df = 3, p < 0.01). Depart con-
tacts were brief and showed relatively little variability, range of 1–5 min. In
contrast, na¨ıve and ignore contacts typically lasted >2 h with high variability,
ranging from <10 min to >7h.
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Na
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Fig. 2. Proportions of different party types by contact type.
DISCUSSION
Chimpanzees residing in the remote forests of the Goualougo Triangle
most often responded with curiosity to our research presence. Comparing
our data with reports from other sites, showed that the proportion of curious
responses is relatively high (Johns, 1996; Tutin and Fernandez, 1991). How-
ever, researchers conducting initial surveys in remote regions of equatorial
Africa have reported similar encounters with groups of curious primates.
Kortlandt (1962) described encounters with chimpanzees that showed little
Table VI. Relationships between contact type and associated factors
Contact Initial Departure Party size Party size Average
type location location initial (increase) overall duration
Na¨ıve Canopy Descend to ground 3.51 (2.78) 6.29 136 min
Ignore Canopy Remain in canopy 2.78 (0.33) 3.11 142 min
Nervous Ground Remain in canopy 3.32 (0.12) 3.44 42 min
Depart Ground Depart on ground 1.63 (0) 1.63 1 min
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378 Morgan and Sanz
fear toward humans in the Democratic Republic of Congo. In Tanzania,
Itani and Suzuki (1967) described encounters with chimpanzees that exhib-
ited curiosity toward their human observers. During a census of primates in
the Ituri Forest, Thomas (1991) found that in remote locations chimpanzees
showed less fear than those that lived in close proximity to humans. They
share a suite of behaviors with chimpanzees in the Goualougo Triangle sug-
gesting that they had limited contact with humans and had not experienced
the negative impacts of human presence, such as hunting, poaching, and
habitat destruction.
During the past two years of surveys in the Goualougo Triangle, we have
observed that the majority of chimpanzees encountered over a large land-
scape responded to us with curiosity. This phenomenon is more robust than
a few curious individuals; it seemed that the entire population was respond-
ing to a novel stimulus in their environment. This was reinforced by several
instances when the chimpanzees showed curiosity toward other objects. For
example, we observed adult chimpanzees exhibiting curiosity toword unat-
tended backpacks left on the path, tarps, and our empty campsites. During
the past two years, we never encountered other humans or their signs—
cut paths, campsites, trees slashed for rubber—in the Goualougo Triangle.
From the history of the study area, it is likely that our presence constitutes
most of these chimpanzees’s only experiences with humans. This is further
substantiated by their initial responses and continued curiosity.
We also observed that an individual’s reaction was deeply integrated
within a group’s response to our presence. Within contacts, individuals
seemed to be socially referencing from others. If an individual crouched
or moved toward us for a better view, others would also exhibit the behav-
ior. A calm chimpanzee’s relaxed behavior seemed to soothe others, even
if the same individuals showed nervous behaviors in different company. In
contrast, a more fearful individual could easily rouse other chimpanzees with
frequent vocalizations and nervous behaviors. Departures also seemed to be
coordinated as all individuals in a group departed one after another through
the canopy or single-file on the ground. The reaction of chimpanzee groups
to our presence prompted us to categorize entire contact events as na¨ıve,
ignore, nervous, or depart (Table VI).
Na¨ıve contacts were characterized by curiosity (Table I), the arrival of
other chimpanzees, and maintaining prolonged contact with observers. Dur-
ing na¨ıve contacts, there were many occasions when several individuals in
a group would continue to show curiosity throughout the encounter. They
would move closer, circle around us in the canopy and on the ground, and
remain for hours intently watching us. The excited and inquisitive vocaliza-
tions of chimpanzees initially contacted seemed to draw others to the loca-
tion. New arrivals often vocalized as they approached. Even chimpanzees
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Na
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that had been contacted several times would join focal groups and monitor
us with interest. On many occasions, we ended na¨ıve contacts with groups
intently watching us depart and sometimes even following us through the
forest.
The discovery of a na¨ıve population and their trust in humans is cou-
pled with an obligation to ensure their long-term protection. Similar to ha-
bituated chimpanzees, their lack of fear toward humans could make them
easy victims of poachers. We have also had na¨ıve contacts with other pri-
mate species that would be vulnerable to hunting, including gorillas (Gorilla
gorilla gorilla), grey-cheeked mangabeys (Lophocebus albigena), and-black-
and-white colobus (Colobus guereza). Serving as both a conservation and
research presence in the Goualougo Triangle, we established a study site
and began systematically to document the ecology and behavior of the
chimpanzees. Within a relatively short time, we observed several behaviors
that have been recorded at long-term study sites, including tool use, meat
eating, food sharing, gestural communication, mating, reassurance, groom-
ing, and nesting. We have also begun to elucidate the social structure, ranging
patterns, and feeding ecology of a main study community.
Due to the rapid expansion of commercial timber extraction and in-
creasing human populations, chimpanzee habitats throughout Africa are dis-
appearing at an alarming rate. However, the discovery of na¨ıve chimpanzees
in northern Congo provides hope that intact habitats and populations still
remain. Initial survey teams documented many aspects of the area that are
important to conservation and science, but it was the na¨ıve encounters with
chimpanzee groups that highlighted the Goualougo Triangle as a conserva-
tion priority. Documentation of the chimpanzee’s na¨ıve behavior assisted in
persuading government officials and the local logging company to preserve
this pristine habitat. In July 2001, the Goualougo Triangle was annexed to
the Nouabal´e-Ndoki National Park as a result of collaboration between the
Wildlife Conservation Society, the Congolese Ministry of Water and Forests,
and Congolaise Industrielle du Bois. This is an example of how research and
conservation efforts can be combined to identify and pursue the protection
of remaining chimpanzee habitats.
ACKNOWLEDGMENTS
We deeply appreciate the opportunity to work in the Nouabal ´e-Ndoki
National Park and especially the Goualougo Triangle. This has been pos-
sible through the support of the Government of the Republic of Congo
and Wildlife Conservation Society-Congo, with special thanks due to D.
Bourges, B. Curran, and J. M. Fay. Grateful acknowledgment of funding is
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380 Morgan and Sanz
due to Columbus Zoological Park, American Zoological Association, and
the Wildlife Conservation Society. In situ facilities and logistical support
have been provided by the Wildlife Conservation Society, Congo. Invalu-
able assistance in the field was provided by R. Mokanga, J. P. Koba, and N.
Massembo. Insightful comments on this manuscript and invaluable mentor-
ship during this project were provided by F. Maisels, R. Sussman, P. Lee, T.
Rasmussen, and A. Fuentes. Suggestions made by C. E. G. Tutin and one
anonymous reviewer greatly improved this manuscript.
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... However, in low-visibility rainforest at Lopé, Gabon, where apes were not hunted, chimpanzees also responded to observers most often with rapid flight [Tutin & Fernandez, 1991]. On the contrary, in the remote forests of the Goualougo Triangle, Republic of Congo, chimpanzees showed intense curiosity rather than fear during encounters with researchers, suggesting that they had no prior experience with humans [Morgan & Sanz, 2003]. At Kibale, Uganda, where human population density surrounding the national park is high, chimpanzees being habituated for tourism ignored or fled from observers in equal measure but also exhibited occasional aggression by charging humans [Grieser Johns, 1996]. ...
... At Kibale, Uganda, where human population density surrounding the national park is high, chimpanzees being habituated for tourism ignored or fled from observers in equal measure but also exhibited occasional aggression by charging humans [Grieser Johns, 1996]. In African great apes, habituationdefined as the acceptance by wild animals of a human observer as a neutral element in their environment [Tutin & Fernandez, 1991]-may take several years to accomplish without provisioning [Bertolani & Boesch, 2008;Doran-Sheehy et al., 2007], but is a requisite first phase before detailed behavioral research can be conducted or successful viewingbased tourism implemented [Bertolani & Boesch, 2008;Blom et al., 2004;Doran-Sheehy et al., 2007;Grieser Johns, 1996;Morgan & Sanz, 2003;Tutin & Fernandez, 1991]. With increasing human penetration into great ape habitats, the conservation implications of habituating populations in humandominated landscapes for research or tourism warrant careful consideration. ...
... Initial responses of visible chimpanzees did not always aptly reflect the predominant group reaction to researchers that characterized the entire encounter. Thus, following Morgan and Sanz [2003] entire encounters were categorized based on the overall response of the chimpanzee party to the researchers during the majority of the encounter. The behavior of non-or barely visible animals was taken into account when it could be reasonably determined. ...
Thesis
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As humans continue to modify natural habitats in Africa, particularly outside of protected areas, the survival of many chimpanzee (Pan troglodytes) populations is dependent on their ability to adapt to human-dominated landscapes, and the willingness of local people to share their environment and resources with these large mammals. Unless hunted, chimpanzees may persist in anthropogenically-modified habitats including forest–farm mosaics, but competition and conflict can characterise their relationship with people. Conservation strategies are needed to facilitate successful coexistence. However, few studies have examined human–ape sympatry in detail. This thesis explores the ecological and behavioural adaptation of a previously unstudied chimpanzee community to an increasingly ‘agriculturalised’ landscape at Bulindi, Uganda. These chimpanzees live in exceptionally close proximity to farmers that exert unsustainable pressure on small unprotected forests. Research was conducted during 21 months between February 2006 and January 2008. Quantitative ecological methods were used to characterise the apes’ habitat and measure seasonal food availability. Indirect methods (e.g. faecal analysis and nest mapping) were employed to investigate chimpanzee diet and range use, supplemented by opportunistic behavioural observations. Riverine forests at Bulindi are rich in chimpanzee foods, but are rapidly being destroyed by people. Important foods in the apes’ diet include both wild and cultivated items; chimpanzees increased consumption of cultivars during the low forest fruiting season. Unique among studied populations in Uganda, Bulindi chimpanzees use tools to dig up subterranean bee nests for honey. Interviews were conducted to survey residents’ attitudes towards chimpanzees and forests. Chimpanzee behaviour is widely perceived by residents to have undergone recent negative changes, including increased crop-raiding and ranging into village areas, which correspond to major land-use changes (i.e. commercial logging and agricultural intensification). Further, adult males exhibit frequent human-directed aggression, apparently in response to harassment and intensifying competition with humans. Most residents fear chimpanzees. Because of poverty, insecure land tenure, inadequate law and policy enforcement, and corruption, local people currently have little incentive to maintain forest on their land. The study concludes that, under present conditions, chimpanzees will not survive at Bulindi or in similar unprotected forest–farm landscapes regionally without immediate, effective intervention. Recommendations for the conservation and management of chimpanzees in human-dominated landscapes are provided.
... Unhabituated wild chimpanzees usually flee when they first encounter researchers [92,93]. Habituation may take months or years, but groups with less negative exposure to humans may show less avoidance, and some may appear relaxed or even intimidate human intruders [94][95][96]. Chimpanzees high up in trees, males, and those in large parties are less skittish than those on the ground, females, or those in small parties [95,97]. Occasionally, chimpanzees living near humans have attacked them, usually in response to provocation or harassment [98]. ...
... Habituation may take months or years, but groups with less negative exposure to humans may show less avoidance, and some may appear relaxed or even intimidate human intruders [94][95][96]. Chimpanzees high up in trees, males, and those in large parties are less skittish than those on the ground, females, or those in small parties [95,97]. Occasionally, chimpanzees living near humans have attacked them, usually in response to provocation or harassment [98]. ...
Article
Information about responses to death in nonhuman primates is important for evolutionary thanatology. This paper reviews the major causes of death in chimpanzees, and how these apes respond to cues related to dying and death. Topics covered include disease, human activities, predation, accidents and intra-species aggression and cannibalism. Chimpanzees also kill and sometimes eat other species. It is argued that, given their cognitive abilities, their experiences of death in conspecifics and other species are likely to equip chimpanzees with an understanding of death as cessation of function and irreversible. Whether they might understand that death is inevitable—including their own death, and biological causes of death is also discussed. As well as gathering more fundamental information about responses to dying and death, researchers should pay attention to possible cultural variations in how great apes deal with death. This article is part of the theme issue ‘Evolutionary thanatology: impacts of the dead on the living in humans and other animals’.
... Chimpanzees also demonstrate a range of responses during encounters with humans. Flight is the predominant response in areas where chimpanzees are hunted (Bertolani & Boesch, 2008), with fleeing, curiosity, aggression or disregarding humans also observed across a range of field sites (Johns, 1996;McLennan, 2010;Morgan & Sanz, 2003;Tutin & Fernandez, 1991). Research examining the effects of the habituation processes have revealed that repeated encounters with humans in the early stages results in acute stress responses for many of the great apes (Blom et al., 2004). ...
Thesis
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In this thesis, I examine the complex entanglements among humans, Cross River gorillas (Gorilla gorilla diehli) and Nigeria-Cameroon chimpanzees (Pan troglodytes ellioti) within the unprotected Mone-Oku Forest, Cameroon. I apply a dual ethnoprimatological and political ecology framework to examine the multifaced interconnections between humans and primates that approaches the Mone-Oku landscape as a combination of social, political and ecological systems. I aim to step away from the ‘crisis’ conservation narrative that labels the local people as the largest threat to these endangered apes and strive for a reflexive ethnographic ethnoprimatology. Through a combined use of botanical surveys, analyses of nesting sites, participant observation and semi-structured interviews, I obtained nuanced ecological and ethnographic insight into the human-ape interface. I found that the chimpanzees and gorillas selected distinct nesting ranges within the Mone-Oku Forest. Plant species preferences in the construction of night nests were also observed for both taxa. Anthropogenic activities within the forest, therefore, have different impacts on the nesting behaviour of the apes. Through ethnography and semi-structured interviews, the importance of cacao (Theobroma cacao) to people quickly became apparent. This was reflected in perceptions that held the Mone-Oku Forest to be more important than the individual species within. In contrast, local perceptions of the apes were often contradictory and context dependant ranging from fear to tolerance, some of which stems from power imbalances with conservation organisations. A reconsideration of the conservation narratives for these apes found them to be incomplete and potentially biased, as they neglect some aspects of human-ape interactions, wider community ecology and the microscales of time. This research highlights the complexity of human, gorilla and chimpanzee intra-actions at a specific site. While perfect solutions to conservation problems are not always possible, conservation programs that acknowledge the importance of cocoa and incorporate the variety of knowledge about cacao farming have the potential to foster positive relationships with these communities, furthering the conservation of these endangered apes.
... In this study, we used 16S rRNA gene sequencing and high-throughput metagenomic sequencing to characterize the fecal microbiota and resistomes of 18 wild central chimpanzees (Pan troglodytes troglodytes) and 28 wild western lowland gorillas (Gorilla gorilla gorilla) from Nouabalé-Ndoki National Park in the Republic of the Congo. These wild animals live in a remote area of the park that was completely naive to human impact before 2003 and identified as the ape population that was least disturbed by humans in 2014 [33,34]. We also collected samples from 81 humans living just outside of the park, including some individuals that work within the park, in the Republic of the Congo. ...
Article
Full-text available
The gut microbiome can vary across differences in host lifestyle, geography, and host species. By comparing closely related host species across varying lifestyles and geography, we can evaluate the relative contributions of these factors in structuring the composition and functions of the microbiome. Here we show that the gut microbial taxa, microbial gene family composition, and resistomes of great apes and humans are more related by host lifestyle than geography. We show that captive chimpanzees and gorillas are enriched for microbial genera commonly found in non-Westernized humans. Captive ape microbiomes also had up to ~34-fold higher abundance and up to ~5-fold higher richness of all antibiotic resistance genes compared with wild apes. Through functional metagenomics, we identified a number of novel antibiotic resistance genes, including a gene conferring resistance to colistin, an antibiotic of last resort. Finally, by comparing our study cohorts to human and ape gut microbiomes from a diverse range of environments and lifestyles, we find that the influence of host lifestyle is robust to various geographic locations.
... It is likely that during that time, the intensity of hunting activities was low in the research site, and the presence of humans was not perceived as a threat by great apes. For example, chimpanzees in the Goualougo triangle (Republic of Congo) were mostly curious (84% of time) about the arrival of researchers (Morgan and Sanz, 2003). In this context, great ape populations can be expected to be at least constant (Sugiyama, 1984) because they do not have natural predators. ...
Thesis
Full-text available
The ongoing global decline in mammal populations has led researchers and conservationists to question which factors drive their abundance and distribution. Specifically, there is an urgent need to understand how the ranging behaviour of mammals determines their response to human-induced environmental changes. Threats such as hunting and habitat fragmentation and degradation through agricultural expansion and logging have received considerable attention. However, a potential threat resulting from the non-consumptive use of natural systems by humans has often been overlooked. The ecological and anthropogenic factors influencing the abundance and distribution of mammal populations in tropical forests were evaluated using great apes (Gorilla gorilla gorilla and Pan troglodytes troglodytes) as focal species in order to improve understanding of the drivers of local extinction of species. To achieve this goal, data on diet, fruit phenology, botany, and nest abundance and distribution were collected in a design involving a sampling grid and line transects. Data were analysed using modelling techniques in R and ArcGIS. The preferred fruiting plants for both gorillas and chimpanzees were more abundant in chimpanzee-preferred nesting habitats, while their fallback fruits were more abundant in gorilla-preferred nesting habitats. The patterns of habitat use by both gorillas and chimpanzees varied seasonally. In the absence of human disturbance, the distribution of gorilla nests was predicted by the availability of their preferred nesting habitats, while the distribution of chimpanzee nests was predicted by elevation and their preferred nesting habitats. However, when considering the research camp and human settlements, the distribution of gorilla nests was predicted first by the distribution of human settlements and then by their preferred nesting habitats, while chimpanzee nests remained predicted by elevation and their preferred nesting habitats. The long-term monitoring of great ape nests in the research site revealed a decline in both gorilla and chimpanzee populations resulting from an increase in hunting activities in the site. Results suggest that in the absence of human disturbance, ecological factors (habitat preference, seasonal patterns of fruit availability, fruit preference, and spatial distribution of habitat types) may be responsible for seasonal changes in mammal population abundance and distribution. Animal species traits (body size, terrestrial/arboreal, level of specialization/generalization, and competitive inferiority/superiority) have a profound influence on the response of mammals to human activities. Due to their spatial flexibility and their reliance on more available fallback food sources when preferred fruits are scarce, gorillas may vacate areas disturbed by hunting and non-hunting human activities and related noise. Chimpanzees, on the other hand, persist in their preferred nesting habitats despite human disturbance due to their high level of specialisation in fruit consumption. Additionally, the competitive dominance of chimpanzees over gorillas facilitated by their grouping patterns may allow them to cope with human disturbance better than gorillas. Human impacts other than direct killing of animals may influence the abundance and distribution of great ape populations and may account for the long-term decrease in population size. As habitat and resource heterogeneity facilitate the local coexistence of gorillas and chimpanzees, preserving both preferred and fallback fruiting plant species is crucial. Patterns observed in great apes may be an indication that human disturbance is also negatively influencing other mammals. However, species may respond differently to human disturbance, depending on their interaction with other sympatric mammals, their level of dietary specialisation, and their interaction with their physical environment. Further research is required to assess how these biological traits affect mammal response to anthropogenic disturbance. Furthermore, future studies should investigate the threshold beyond which the non-consumptive use of natural systems by humans becomes detrimental to species and their habitats.
... Corridor conservation is a relatively new field in equatorial Africa, but given the expansion of natural resource extraction industries in forestry and mining sectors and the development of associated hard infrastructures (Laporte et al., 2007) it will likely be necessary on behalf of conserving chimpanzees in the Congo Basin. The prospects for such strategies remain high given there still persist extensive chimpanzee populations in central and eastern Africa that have as yet to be disturbed by present day anthropogenic impacts (Morgan and Sanz, 2003;Hicks et al., 2014). Further, Junker et al. (2012), by relating ape presence information to environmental and human impact factors, predicted that geographical connectivity of patches within the Congo Basin of suitable habitat are promising, especially in the north-eastern part of the Republic of Congo and the eastern parts of the Democratic Republic of Congo. ...
... Such a procedure, however, requires animals to be kept in captivity or wild animals to be well habituated to humans which may limit the ecological validity of the respective data. Furthermore, locating wild animals on a regular basis might be difficult in certain species and terrain even if animals are habituated, and habituation is not always desirable because it is time-consuming (Bertolani and Boesch, 2008) and may expose animals to threats of poaching (Morgan and Sanz, 2003). ...
... The Goualougo Triangle, between the Ndoki and Goualougo Rivers, was believed to be one of the least-disturbed areas in all of Central Africa. Indeed, the initial surveys that led to the creation of the NNNP showed the forest to be intact, undisturbed and inhabited by apes that responded as if they had little or no experience with humans (Fay, personal communication, 1999;Morgan & Sanz, 2003). The Djéké Triangle was a second important conservation area for great apes within the logging concession. ...
Chapter
Lessons learned: What worked?Lessons learned: Challenges to overcomeConclusion
... The Goualougo Triangle, between the Ndoki and Goualougo Rivers, was believed to be one of the least-disturbed areas in all of Central Africa. Indeed, the initial surveys that led to the creation of the NNNP showed the forest to be intact, undisturbed and inhabited by apes that responded as if they had little or no experience with humans (Fay, personal communication, 1999;Morgan & Sanz, 2003). The Djéké Triangle was a second important conservation area for great apes within the logging concession. ...
Chapter
Historically, the conservation of forests and wildlife has focused on the creation of national parks and reserves. However, only 9% of protected areas are larger than 14,000 hectares, likely making them too small to conserve ecosystem services and prevent loss of wide-ranging keystone species such as elephant and leopard. New approaches are needed that extend conservation beyond protected area boundaries into areas where economic considerations prevail. The book describes one such emerging model of conservation: the integration of the private sector into partnerships to protect biodiversity and improve forest management. While such partnerships are being created in nearly every sector of resource extraction, detailed analyses of how such partnerships work and whether they benefit biodiversity conservation are rare. Using a case study from the Congo Basin, the book examines principles of conservation and partnership, and provides technical and methodological details to replicate an innovative conservation model. It presents concrete solutions for expanding conservation across multi-use landscapes, a necessary action as industry expands to all the corners of the globe.
Chapter
A fundamental step in the management and conservation of wild species is advancing our understanding of how animals perceive and use their habitat. Spatial variation in risk either from natural predation or human disturbance generates a “landscape of fear” that can be measured and assessed using experimental patch approaches such as giving-up densities (GUDs). For primates inhabiting a matrix of human habitation, exotic plantations, and indigenous forest, it is possible to explore the “risk-disturbance hypothesis,” which posits that human risk parallels natural predation risk in its effects on animals’ habitat use and decision-making. Here we report on a combination of studies on arboreal samango monkeys (Cercopithecus albogularis spp.) and their risk-sensitive foraging at two sites subject to varying anthropogenic pressures. Using GUDs experiments, we documented pronounced effects of humans on monkeys’ patch use but the impact of humans did not simplistically follow predictions from the risk-disturbance hypothesis. At a site with limited human infrastructure, monkeys exploited food patches at typically high-risk strata (ground level) more intensively in the presence of researchers, whom they likely perceived as shields against terrestrial predators (leopards Panthera pardus, caracals Caracal caracal). Meanwhile, at a predator-poor site where monkeys regularly came into contact with human infrastructure and gardens (adjacent to indigenous forest), the experiments indicated that monkeys preferred to forage in indigenous forest given experimental patches in both forest and gardens, where they showed sensitivity to risk (likely from both humans and domestic dogs Canis lupus familiaris). However, once already in gardens, monkeys depleted patches to extents similar to inside indigenous forest. In this chapter, we also elaborate on monkeys’ risk-sensitive responses to negative, neutral, and rewarding objects associated with humans, and explore the impact of prior experience on risk-taking behavior in proximity to humans and their infrastructure. We conclude that the risk-disturbance hypothesis cannot be used as a blanket term to describe primates’ interactions with humans, as we show here how nuanced and flexible samango monkeys’ risk-taking responses are.
Article
Full-text available
Research on lowland gorillas (Gorilla g. gorilla) and chimpanzees (Pan t. troglodytes) began at the 'Station d'Etudes des Gorilles et Chimpanzes’ in the Lopé Reserve, central Gabon, in 1983 and is on-going. This paper lists 676 species of plants belonging to 91 families that occur in the 50 sq. km study area. Data on trees with diameters of 10 cm or more were collected systematically along line transects and opportunistic collections of fertile plants were made. For each plant species, the life-form, habitat preference and density (for trees recorded on transects) are listed. For plants that provide food for gorillas and chimpanzees, the part eaten is given. The plant species list is not complete but shows the flora of the SEGC study area to be diverse. The seven habitat types described range from Savanna to Closed Canopy Forest but the study area is dominated by Marantaceae Forest. Gorillas and chimpanzees at Lope have diverse diets and obtain food from plants in all of the habitat types. Some minor (in terms of area) habitats provide large amounts of food in particular seasons. Comparison of ape diets in different parts of Africa can only advance if vegetation inventories for each study site are compiled and published.
Chapter
Wild primates show a variety of responses when primatologists arrive to study them. Some are very shy and flee rapidly, while others lack fear and are easy to approach and observe. Habituation is the term used to describe the acceptance by wild animals of a human observer as a neutral element in their environment. The process is rarely described, as it is commonly regarded as a means to an end; namely, the progression to a state that allows the natural behaviour of a species to be observed and documented.
Article
Preliminary results of an extensive survey on the diurnal primate fauna in south-western Congo are reported. The survey was carried out in Region de Niari and Lékoumou from November, 1992 to December, 1992. I confirmed the presence of Pan troglodytes troglodytes and Cercopithecus pogonias by direct observations and the presence of Gorilla gorilla gorilla, Mandrillus sphinx, Cercopithecus cephus and C. nictitans by indirect evidences. Local people informed the presence of Colobus satanus, Cercocebus torquatus, C. albigena and Miopithecus talapoin, but I could not confirm them myself. Population densities of Pan t. troglodytes in the area were caluculated from nest counts. The population densities were higher in the areas near the border of Gabon and in the eastern part of Region de Lékoumou than the other areas. The differences in the population densities in each area seemed to be related with differences in hunting pressure. Average population density in the study areas was far lower than that in Ndoki Forest in the northern part of Congo, but allmost equal to throughout Gabon or in the part of Equatorial Guinea.
Article
A census was made of gorilla and chimpanzee populations throughout Gabon between December 1980 and February 1983. The aim of the census was to estimate the total numbers of both species and describe their distributions. The method was based on nest counts from line transects which allowed the calculation of population densities of all individuals except suckling infants. Fifteen types of habitat were recognized and defined in terms of their structural features. In the initial phase of the study we did transects in each habitat-type and computed mean densities for each species in each habitat-type. In the second phase of the study we estimated the sizes of gorilla and chimpanzee populations throughout the country by extrapolation from these population density values. We did transects in all areas of the country and conducted interviews to check the accuracy of the population totals obtained by extrapolation. Corrections were made to the extrapolated totals to take into account different levels of hunting pressure and other human activities found to modify ape population densities. Total populations of 34,764 gorillas and 64,173 chimpanzees were estimated. An error of ± 20% was associated with the estimated population totals, which allows the conclusion that Gabon contains 35,000 ± 7,000 gorillas and 64,000 ± 13,000 chimpanzees. The figure for gorillas is much larger than previous estimates. This seems to be because (1) gorillas occur in almost all types of forest and are not restricted to man-made secondary forest as had been though; and (2) the geographical distribution of gorillas in Gabon is wider than previously believed. Gabon's large areas of undisturbed primary forest offer exceptional potential for conservation, not only of gorillas and chimpanzees, but also of the intact tropical rain forest ecosystems which they inhabit.
Article
Over an eight-year period, a total of 174 food items were recorded for chimpanzees (Pan t. troglodytes) in the Lopé Reserve in central Gabon. Plant foods, principally fruit, dominated the diet but insects were eaten regularly, and predation on at least three species of mammal occurred infrequently. The diversity of the vegetative component of the diet (leaves, stems, and bark) was probably underestimated by fecal analysis. Comparison of chimpanzee diet at Lopé with that of sympatric lowland gorillas showed the majority of foods were eaten by both species (73% of chimpanzee food items and 57% of gorilla food items). The overlap of fruit species was greater (82% and 79%, respectively) than that of other food classes. Both chimpanzees and gorillas harvested the majority of their plant foods arboreally (76% and 69%, respectively). The high degree of dietary overlap suggested that ecological competition between these two closely related species might exist. Few overt signs of competition for food either between or within species were observed but when fruit was scarce, the diets of the two species showed greatest divergence. The major differences between chimpanzee and gorilla diet at Lopé were the larger quantities of vegetative foods regularly eaten by gorillas and their ability to resort to a diet dominated by vegetative foods when fruit was scarce. In these respects, chimpanzees at Lopé resembled populations of Pan troglodytes studied elsewhere while Lopé gorillas resembled mountain gorillas (Gorilla g. beringei) and bonobos (Pan paniscus) in their greater dependence on vegetative foods. © 1993 Wiley-Liss, Inc.