Pan Africa NewsThe Newsletter of the Committee for theCare and Conservation of Chimpanzees, andthe Mahale Wildlife Conservation SocietyVol. 12 , No. 1

JUNE, 2005
P. A. N. EDITORIAL STAFF

CONTENTS:

Chief Editor:
Toshisada Nishida, Japan Monkey Centre, Japan
Associate Editors:

OBITUARY
Professor Shigeo Uehara: Founding Member ofChristophe Boesch, Max-Planck Institute, Germany

the Mahale Wildlife Conservation Society

Jane Goodall, Jane Goodall Institute, USA

Toshisada Nishida

2

Takayoshi Kano, Kyoto Sangyo University, Japan
Tetsuro Matsuzawa, Kyoto University, Japan<NOTE>

William C. McGrew, Miami University, USA

Possible Intergroup Killing in Chimpanzees inJohn C Mitani, University of Michigan, USA
Vernon Reynolds, Oxford University, UK
Yukimaru Sugiyama, Tokai-Gakuen University, Japan
Richard W. Wrangham, Harvard University, USA

the Kalinzu Forest, Uganda
Chie Hashimoto and Takeshi Furuichi

4<NOTE>

Editorial Secretaries:

Survey of the Southern Part of the Mahale

Noriko Itoh, Kyoto University, Japan

Mountains

Koichiro Zamma, Kyoto University, Japan
Michio Nakamura, Kyoto University, Japan

Instructions to Authors:
Pan Africa News publishes articles, notes, reviews, forums,
news, essays, book reviews, letters to editor, and classified

Michio Nakamura, Hitonaru Nishie andCrispin Mwinuka

6<NOTE>
Rejecting a Bit of Meat to Get More
Koichiro Zamma

8

ads on any aspect of conservation and research regarding
chimpanzees (Pan troglodytes) and bilias (P. paniscus). Contributors are requested to write in English and the papers<ARTICLE>

except forums, reviews and essays should usually be 1,000Life Span of Chimpanzee Beds at the Mahale

words or less. Manuscripts should be submitted by e-mail to:

Mountains National Park, Tanzania.

pan_ed@jinrui.zool.kyoto-u.ac.jp
Photos and figures, however, should be sent by air mail to:T. Nishida, Japan Monkey Centre, 26 Kanrin, Inuyama, Japan.
Publication of the next issue will be December 2005.
Deadline for manuscripts is the end of October.
Printed on recycled paper

Hiroshi Ihobe

10

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Pan Africa News, 12(1), June, 2005

OBITUARY
Professor Shigeo Uehara:
Member of the Mahale Wildlife
Conservation Society
Toshisada Nishida
Japan Monkey Centre

Professor Shigeo Uehara (Uehara-san) sadly
passed away on the morning of August 24, 2004,
at only 58 years old. Uehara-san was my closest
colleague in the Mahale Mountains Chimpanzee
Research Project and simultaneously one of mymost reliable friends.
Uehara-san's important contributions to thestudy of chimpanzees include the followings: He
found that K-group chimpanzees exploit termites
belonging to the genus Pseudocanthotermesby different techniques in accordance with thetermite life cycle -- fishing for soldiers at the
beginning of the rainy season, catching winged
termites with their hands at the end of the rainyseason, and taking termite soils all year round.
He was most interested in the origins of divisionof labor by sex, and sought to examine sex
and age differences in chimpanzee subsistence
behavior. He found that male chimpanzees areengaged more in predatory behavior and females
more in eating ants. Furthermore, he clariﬁed that
adult males ingest piths of grasses significantly
faster than adolescent males. Moreover, bycomparison with the data from Gombe and Tai, heclariﬁed the characteristics of predatory behavior

Photo 2. Wantangwa, a K-group female, puts herbark probe into the nest of Pseudacnthotermes
spiniger (photo by S. Uehara).

Photo 1. Uehara-san in 2002

displayed by chimpanzees at Mahale.
He took the body weight of chimpanzees
and derived an interesting conclusion that the
chimpanzees of Gombe are significantly smaller
than those of Mahale although they belonged
to the same subspecies. He explained this local
difference by the less nutritional diet at Gombe,
which is ultimately a result of differences invegetation. Ecologically important is his ﬁndingthat body weights reach their minimum in the
middle of the rainy season, which is congruent
with the recent ﬁnding from phenological researchthat fruit production is lowest at Mahale during
this season.
Uehara-san also made an important contribution
to the understanding of chimpanzee socialorganization. He concluded that the chimpanzee
social unit is a bisexual group, rejecting the maleonly unit hypothesis. This conclusion was drawn
after a detailed analysis of long-term data on
female transfer and association patterns of males
and females. He examined examples of defeatedalpha males who were ostracized by other adultmales and concluded that only the ex-alpha males
that can maintain the social nexus with some other
adult males when living a lonely life can return tothe unit group. He also reported a heart-warming
episode in which an unrelated female adopted amale infant when his mother was suffering from
illness. After a week she returned the charge tothe recovered mother.
Uehara-san's contribution to the Mahale study
includes the most basic part of research such ascompilation of both a Tongwe-Latin dictionaryof plants and the list of chimpanzee food plants,

Pan Africa News, 12(1), June, 2005

Photo 3(right). Chausiku and her son Katabi holdthe termite hill of P. spiniger. Chausiku has a barkprobe in her mouth (photo by S. Uehara).

which was based on his excellent knowledgeof botany and systematics. It should not be
forgotten that Uehara-san played a crucial role in
the initial study of M group, particularly in theindividual identiﬁcation and christening of many
adult females and immature chimpanzees in 1973.
With considerable dedication by Mariko HiraiwaHasegawa, Toshikazu Hasegawa and Kenji
Kawanaka to this venture, his effort formed thebasis of the long-term research that is continuing
through many researchers and students.
Uehara-san's research career was not limited
to Mahale. He studied the ecology of bilias(bonobos) in the swamp of Yalosidi, and foundthat swamp was used by two antagonistic unitgroups of bilias to feed for 8 species of aquaticplants. He was one of the first scientists toobserve that bilias mated in the ventro-ventral
position while the female was literally wet in theshallow water. His masters thesis focused on
the temperate components of food compositionof Japanese macaques. From detailed analyses
he hypothesized that Japanese macaques had
migrated to Japan via the western (Korean) route

Photo 4. Kasonta, one of the alpha males that could
return to the alpha position after having been
ostracized (photo by S. Uehara).

3from the Asian continent and moved northward.
Uehara-san was so warm, kind and mild in his
character that he was loved and respected by all
those who knew him. One of the most interesting
aspects of his character was that he was fastidious
about fieldwork preparation. Before setting out
into the bush in the morning, he would thoroughly
check all his belongings, ranging from his
binoculars and field notes to his compass andcolored pencils.
For more than five years Uehara-san had
expressed his desire to visit Mahale with his wife,
son and daughter. I am deeply sad that he could
not realize his dream.
Uehara-san will be greatly missed by all who
knew him and worked with him.

<NOTE>
Possible Intergroup Killing in
C h i m p a n z e e s i n t h e K a l i n zu
Forest, Uganda
Chie Hashimoto1 and Takeshi Furuichi2
1. Primate Research Institute, Kyoto University
2. Faculty of Foreign Studies, Meiji-Gakuin University

INTRODUCTION
Several studies have reported intergroup killingof adult male chimpanzees (Pan troglodytes
schweinfurthii) 1,2,3. Although there has been
criticism that the intergroup killing occurred asa result of artificial provisioning or playback
experiments, a recent study has conﬁrmed that it
occurred in a wild group in the Kibale National
Park, Ngogo group, a group that had not been
under any artificial influences 3. We have also
observed a wild group of chimpanzees, inthe Kalinzu Forest Reserve, Uganda, a groupwith no experience of artificial provisioning
or experiments. Here, we report an indirect
observation that suggests the occurrence of theintergroup killing of an adult male.
METHODS
We have been studying wild chimpanzees in
the Kalinzu Forest Reserve since 1992 4. We
started to habituate one group, M group, in June
1997. Most of the adult male members were
well habituated by 20014. The observations forthis report were conducted from August 2003 to
October 2003. During this period, we followed
the M Group and recorded feeding behaviors and4

Pan Africa News, 12(1), June, 2005

Fig. 1. The carcass of an adult male chimpanzee. The grass was trampled aroundthe carcass.

social interactions using the focal animal and ad
lib sampling methods.
RESULTS
While we stayed in camp, on September 13,
2003, we heard loud vocalizations comingfrom numerous chimpanzees in the forest. We
estimated that the vocalizations had come froma distance of about 500 m. The vocalizations
included pant-hoots and screams. This was
unusual because it continued for more than ten
minutes, without interruption.
Two weeks later, we found the carcass of a malechimpanzee in the area where we had heard the
vocalization. Judging from the condition of the
carcass, the chimpanzee had died two to three
weeks previously (Fig. 1). We also found signs
of ﬁghting within 10 m of the carcass: a wisp ofchimpanzee hair on the ground, broken branches,
and trampled grass.
The carcass was identiﬁed as a prime adult malechimpanzee from a photo-identification of theteeth (Mouri and Nakai personal communication).
Since that time, a prime adult male, named Nui,
who was estimated to be 30-35 years old, has
never been observed. As all the other adult malemembers have been confirmed to be alive, we
postulate that the carcass was that of Nui.
In 2003, the M group home range was narrower
than in the previous year, and we frequently
observed a neighboring group in the area fromwhich the M group had retreated. The carcass
was found on the boundary of the M group homerange in this area (Fig. 2). We also observed threeagonistic encounters with a neighboring groupnear the boundary. One case occurred on the same
day that we observed the carcass, 100 m awayfrom it. We also observed patrolling by the M
group males more often than we had in previous
study periods. Based on these circumstances, we
postulated that Nui had been killed in an agonistic
interaction between the groups.
DISCUSSIONIntergroup killing in chimpanzees has beenreported at several study sites1, 2, 3. Although we
did not make a direct observation, the possible
killing occurred when a neighboring group
invaded the home range of M Group. Since
2001, a part of the home range of the neighboringgroup has been logged. The neighboring group
appears to have shifted its home range eastward,
following deforestation in their home range.
Previous studies have suggested that intergroupkilling increases survivorship for the attackers byincreasing territory size3. Our study also suggeststhat a territory shift or expansion caused an intergroup killing in chimpanzees.
ACKNOWLEDGEMETNSWe thank the Uganda National Council for Science andTechnology, the Uganda National Forestry Authority, theUganda Wildlife Authority. We also thank Dr. Mouri
for the identification of the carcass. This study was
supported by a grant from the Monbusho International
Scientiﬁc Research Program (#12375003 to T. Nishida).

Pan Africa News, 12(1), June, 2005

5
INTRODUCTION
The Mahale Mountains National Park contains
the majority of chimpanzees (Pan troglodytes
schweinfurthii) in Tanzania 1. However, after
initial research stages, studies have mainly
focused on habituated chimpanzee groups (see2 for details) that inhabit the northern part ofthe park. Consequently, recent information on
unhabituated chimpanzee groups is mostly fromadjacent groups of the main study group, M group(e.g, 3, 4, 5, and 6). Although there have been
recent surveys further to the north7 and further tothe east8, no systematic survey further south has
been recently conducted.
The objective of this survey is to obtain general
information of the southern part of the park:
the occurrences of chimpanzees and other large
mammals, the vegetation types, and the degreeof human disturbance that can be useful for areaconservation.

Fig. 2. The M group home range in the current
study period (2003), and in the previous year
(2002). The locations of the camp, carcass, andthe occurrence of agonistic encounters are also
indicated.

REFERENCES
1. Nishida T, Hiraiwa-Hasegawa M, Hasegawa T
and Takahata Y. 1985. Group extinction and femaletransfer in wild chimpanzees in the Mahale National
Park Tanzania. Z. Tierpsychol. 67:284-301.
2. Goodall J. 1986. The Chimpanzees of Gombe,
Harvard University Press, Cambridge, MA.
3. Watts DP. 2004. Intracommunity coalitionary
killing of an adult male chimpanzee at Ngogo,
Kibale National Park, Uganda. Inter. J. Primatol. 25:
507-521.
4. Hashimoto C, Furuichi T, Tashiro Y. 2001. Whatfactors affect the size of chimpanzee parties in
the Kalinzu Forest, Uganda? Examination of fruit
abundance and number of estrous females. Int. J.
Primatol. 22: 947-959.

<NOTE>
Survey of the Southern Part of
the Mahale Mountains
Michio Nakamura1, Hitonaru Nishie1 andCrispin Mwinuka2, 3
1 Kyoto University
2 Mahale Mountains National Park
3 Mahale Mountains Wildlife Research Centre

METHODSWe made our survey from September 6-11
2004 at the end of dry season. We first went toan estuary of the River Lubugwe by boat andthen climbed a ridge to Mt. Kakunjila. After
heading east for a while, we crossed the Katimba
Valley and headed southeast for Kalya. From
Katimba to Kalya, we tried to walk as straight as
possible. The survey route was traced by a global
positioning system.
We counted chimpanzee beds found from thesurvey route and estimated the distance from theroute by eye. We roughly estimated the age ofthe beds and identified the species of their hosttrees. Chimpanzee vocalization, food remains, orfeces were also recorded whenever encountered.
We also recorded direct and indirect evidence ofother large mammals and made rough sketchesof vegetation types and human disturbance (e.g.,remains of cultivation, ﬁre, etc.).
RESULTS
Figure 1 shows the survey route. From the
Katimba to the Msilambula Valleys, we walked
almost straight southeast. However, because we
could not ﬁnd running water in Msilambula where
we had planned to spend the night, we headed east
for another 10 km or so to find water. Between
River Lumbye and Kalya, a wide range of area
was burned and the vegetation was damaged. We
sometimes saw large fallen trees that were stillburning.
The evidence for large mammals is summarizedin Table 1. Direct observations of mammals were6rare, perhaps because of the destroyed vegetation.
Animals may have detected us before we noticed
them. Although much of the chimpanzee
evidence we found (plotted in Figure 1) was oldbeds, we heard calls twice and saw some fresh
feces. Table 2 shows the species of the host treesof the chimpanzee beds.
DISCUSSION
Judging from the distribution of chimpanzee
evidence, the ranging patterns of known
groups, the vegetation, and the geographicalcharacteristics, we estimated that our survey
area covered the ranges of ﬁve unit groups, eachmainly utilizing the riverine forests of Lubugwe,
Msuma, Katimba, Lumbye, and Msilambula,respectively. We need additional surveys to
conﬁrm our assumptions.
To estimate the number of chimpanzees
inhabiting this area, we need information of the
speed of bed decay. Since most bed trees wefound were Brachystegia, which are common
in Miombo woodlands, bed decay data for thesetree species have to be collected in dry Miombo
woodlands.

Pan Africa News, 12(1), June, 2005

We tried to walk straight to gather less biased
data of chimpanzee beds. However, this was
difﬁcult due to two reasons. One is the landscape.
Although we managed to cross the Katimba
Valley without any special equipment, we had
to cautiously select the safest route, and so we
could not merely walk straight. Secondly, wequit walking straight because of a lack of water.
Unlike a census in moist rain forests, it is hard
to find water in a savanna woodland during thedry season. This is a serious obstacle when
considering a wider census in Mahale.
Just as the eastern area of the Mahale National
Park 8 , the area south of Lumbye was badly
burned. Even here we found old chimpanzee beds
(especially around Msilambula), but we did not
ﬁnd recent evidence in such dry and burned areas.
This suggests that chimpanzees utilize this area
only in rainy season and migrate to other areas(perhaps near the lakeshore1) in dry season. If so,it means that the chimpanzees are forced to range
wider because of human disturbance even within
the protected area. An effective ﬁre management
plan is promptly required to cover the entire areaof the park.

Pan Africa News, 12(1), June, 2005

7

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Pan Africa News, 12(1), June, 2005

ACKNOWLEDGMENTS

This survey was financially supported by The Inui
Memorial Trust for Research on Animal Science.

REFERENCES
1. Kano T. 1972. Distribution and adaptation of thechimpanzee on the eastern shore of Lake Tanganyika.
Kyoto Univ Afr Studies 7:37-129.
2. Nishida T (ed). 1990. The Chimpanzees of theMahale Mountains. University of Tokyo Press,
Tokyo.
3. Itoh N, Sakamaki T, Hamisi M, Kitopeni R,
Bunengwa M, Matumla M, Athumani K, Mwami
M, Bunengwa H. 1999. A new record of invasion by
an unknown unit group into the center of M groupterritory. Pan Afr News 6: 8-10.
4. Nakamura M, Shimada M. 2002. Report of extensive
survey in northwestern area of the Mahale Mountains
National Park, Tanzania. Unpublished Report to
COSTECH, TANAPA and TAWIRI.
5. Shimada M. 2003. A note on the southernneighboring groups of M group. Pan Afr News
10:11-14.
6. Uehara S 2002. Evidence of the leaf-clipping
behavior by a chimpanzee of an unhabituated group
at Mahale. Pan Afr News 9: 3-4.
7. Zamma K, Inoue E, Mwami M, Haluna B, Athumani
S, Husen S 2004. On the chimpanzees of Kakungu,

Karobwa and Ntakata. Pan Afr News 11: 8-10.
8. Nakamura M, Fukuda F 1999. Chimpanzees to theeast of the Mahale Mountains. Pan Afr News 6: 5-7.
9. Nishida T, Uehara S, Kawanaka K (eds) 2002. [TheMahale Chimpanzees.] Kyoto University Press,
Kyoto, in Japanese.

<NOTE>
Rejecting a Bit of Meat to Get
MoreKoichiro Zamma
Primate Research Institute, Kyoto University

INTRODUCTION"A variety of interactions involving
interindividual transfer of possession of food items
occurs along a spectrum approximating degrees ofvolition1," food sharing is one interesting behavior
among chimpanzees. I will present a case study inwhich a wild infant chimpanzee rejected a small
piece of meat offered by her mother. Infants learn
about many kind of foods they cannot processby themselves2. However, shared foods are notalways good. In captivity chimpanzee mothers

Pan Africa News, 12(1), June, 2005
have been observed to offer only unpalatable parts
to their infants when they initiate the sharing3.
Can infants obtain desirable foods when offeredundesirable ones? Here I will show a possible
case of flexible negotiation between a possessor
and a non-possessor.
RESULTS
Phase 1: reluctant acceptance. I conducted
research on grooming among chimpanzee infantsin the M Group at Mahale Mountains National
Park, Tanzania, from May to July, 2004. On June
30, at 11:28, Kalunde, an old male, caught a red
colobus. At 13:17, Fatuma, an old female, held
and ate a chunk of this colobus meat transferredby Kalunde. Fatuma had two female infants,
Flavia (5 yrs) and FT03 (1 yr). Flavia waseating a piece of meat at a distance of 1 meterfrom Fatuma. At 13:18, Flavia whimpered andextended her left hand to Fatuma. Fatuma stopped
eating and held the rest of the chunk of meatin her left hand, and then started to approach
Flavia. Flavia put her hand on the meat, but
Fatuma twisted her left wrist free of Flavia's hand.
Fatuma continued to approach, showing Flavia a
bit of meat, roughly 1 cm3, between her lips andfed it to Flavia mouth to mouth. Flavia chewed
it. Fatuma put the chunk into her mouth. Flavia
whimpered again and reached for Fatuma's mouth.
When Flavia gave a noisy whimpering scream,
Fatuma embraced Flavia. However, Flavia
continued to whimper and touch her mother'smouth. After Fatuma started to groom the head ofFlavia, as if trying to divert Flavia's eyes from the
chunk, Flavia stopped whimpering and chewed
the bit of meat again.
Phase 2: rejecting a bit of meat. A quarter hour
after phase 1, Flavia again solicited a chunk ofmeat held by Fatuma. At 13:34, Fatuma showeda bit of meat between her lips and offered it to
Flavia. However, Flavia rejected it. Fatuma
groomed Flavia. At 13:35, Flavia ate a chunkof meat held by Fatuma. Fatuma also ate theopposite end of it without paying attention to
Flavia.
Phase 3: object gained, meat lost. Fatuma
continued to hold the chunk of meat. Flavia
solicited the chunk of meat, as in phases 1 and 2
until 14:23. At 14:24, Flavia solicited and took
the chunk, which resembled a piece of fur. Flavia
put the fur into her mouth and chewed it until
14:39, after which I lost track of them.

9
DISCUSSION
Rejecting offered food among wild chimpanzees
has not been reported, as far as I know, and I
have observed it only once in my research. Why
did Flavia reject a bit of meat, even though she
solicited it? Flavia was five years old, which ismature enough to know that meat is good food,and she had already been eating some bits of meat
before rejecting it. However, the rate of meatintake was low. So, Flavia wanted more meat ina short time and asked for the chunk of meat heldby Fatuma. In phase 1, Flavia was compelled toaccept the offer, a bit of meat, from her mother. In
phase 2, Flavia rejected the bit of meat, continued
her solicitation, and succeeded in eating the chunkof meat. Though a scrap of meat is still meat, it
may mean little for a growing infant.
Why did Fatuma offer a bit of meat? She
seemed skillful in calming her whimperingdaughter. It is not that she refused absolutely
Flavia's solicitation. Fatuma agreed to therequest for meat but only a little bit. If Flavia
compromised on just a little quantity of meat,
Fatuma could eat more meat. Grooming also
helped to divert Flavia's attention from the chunkof meat (phase 1).
Food is not always distributed equally even
if a possessor divides, offers, and shares it.
A possessor occasionally offers not only an
unpalatable part of food3 but also a small amountof food. If a non-possessor solicits and steals
meat, the non-possessor can eat as much as
possible. However, when a possessor divides
meat, the possessor can control it for selﬁsh ends.
Fatuma divided the meat into two unequal pieces
and used two food sharing tactics: not to tolerate
the solicitation for a chunk and to offer a smaller
piece. Flavia used two other tactics: refusing toaccept the offer and continuing solicitation for alarger piece (phase 2). In the end, Flavia ate the
chunk of meat. However, the meat might decreasein value for the possessor, Fatuma, after she had
eaten more of it4. It is difﬁcult to decide whether
the negotiation really lowered the threshold ofresistance of Fatuma.
REFERENCES
1. McGrew WC. 1975. Patterns of plant food sharing
by wild chimpanzees. In: Kondo S, Kawai M, Ehara
A (eds), Contemporary Primatology, Karger, Basel,
pp 304-309.
2. Nishida T, Turner LA. 1996. Food transfer between
mother and infant chimpanzees of the Mahale
Mountains National Park, Tanzania. Int. J. Primatol.
17: 947-968.
3. Ueno A, Matsuzawa T. 2004. Food transfer between

10

Pan Africa News, 12(1), June, 2005

chimpanzee mothers and their infants. Primates 45:
231-239.
4. Feistner ATC and McGrew WC. 1989. Food-sharing
in primates: a critical review. In: Seth PK, Seth S(eds), Perspectives in primate biology, vol. 3, Today& Tomorrow’s Printers and Publishers, New Delhi,
pp 21-36.

<ARTICLE>
Life Span of Chimpanzee Beds at
the Mahale Mountains National
Park, Tanzania
Hiroshi Ihobe
Sugiyama Jogakuen University

INTRODUCTION
Population estimates of wild chimpanzees havebeen conducted by a variety of methods. Many
researchers have adopted nest- or bed-countmethods to estimate chimpanzee populations dueto the difﬁculty of making direct observations of
unhabituated chimpanzees1, 2, 3, 4, 5.
Ghiglieri1 developed a chimpanzee population
estimation method in which some parameters,such as average life span of beds, are assumed
to be different at each study site and thus not
obtained simply by bed censuses. Tutin andFernandez2 modified Ghiglieri's formula to take
into account the non-random distribution ofbeds. However, this method also requires theaverage life span of beds. Hashimoto 3 as wellas Plumptre and Reynolds4 developed a method
based on newly built beds. This method does
not require average life span of beds but does
require repeated censuses. Also, all three methods
require presumptions such as the proportion of
bed-building chimpanzees, rate of reuse of beds,
and day-bed production to precisely estimate
chimpanzee populations.
This paper presents the preliminary results ofa study on the life span of beds at the Mahale
Mountains National Park, which was made to
examine the variations among the study sites.

METHODS
The Mahale Mountains National Park is locatedon the eastern shore of Lake Tanganyika. The
chimpanzees in the Park have been studied since
19656. The vegetation type in the study area wassemi-deciduous or semi-evergreen gallery forest
and Brachystegia woodland. The rainy season isfrom October to May, and the dry season is from
June to September.
The field work was conducted from August to
December 1995. Forty-three beds constructed on
known dates by habituated M group chimpanzees
were monitored about once a week to determine
the life span of beds. Tree species, estimatedheight, and the presence of shade for each bed
were recorded. All of the beds monitored wereconstructed in August.
Age-class of beds was defined according to
Tutin and Fernandez 2, as shown in Table 1. I
considered the life span of each bed to be theperiod from the date of construction to the datemidway between the last weekly inspection when
it was recognizable and the ﬁrst when it was not.
RESULTS and DISCUSSION
Out of 43 beds, two beds (4.7%) were assumed
to be reused by the chimpanzees. These beds
were excluded from the calculation of life span.
Mean and SD of life span of 41 beds were 130.7
days and 45.7 days, respectively. The life span ofbeds ranged from 30 to 189 days.
Figure 1 shows a decay curve for beds monitored
during the study period. Plumptre and Reynolds4
reported that the decay of beds in their study
approximated an exponential decay curve, but
this phenomenon was not found in this study.
Plumptre and Reynolds 4 suggested that the
decay rate should be calculated while assuming
exponential decay, since this is not likely to begreatly affected by a small number of beds that

Pan Africa News, 12(1), June, 2005

last a very long time; however, the present study
did not support this assumption.
Monitored beds were usually constructed intrees, the products (fruits, leaves or piths) ofwhich the chimpanzees fed on (Table 2). Almost
half of the monitored beds were constructedin Pycnanthus angolensis trees. The M groupchimpanzees frequently fed on the fruits of thistree during the study period.
The difference in mean life span of beds between
two tree species (Pycnanthus angolensis and
Xylopia parviﬂora) was not signiﬁcant (Table 3).
The difference in mean life span of beds among
different levels of shade at the beds was also
insigniﬁcant for all beds and for beds constructedin Pycnanthus angolensis trees (Table 4).
Table 5 summarizes the mean life span ofchimpanzee beds at several study sites. Mean
life span of beds in this study is slightly longer
than that in the work of Ghiglieri 1 or Tutin
and Fernandez 2 but slightly shorter than thatof Skorupa cited in Plumptre and Reynolds 4.

11

Plumptre and Reynolds4 used a different deﬁnitionof the decay of beds: if the bed had lost all of its
leaves (even though dead twigs might be present),
it was not counted as a bed. Using this deﬁnition,
the mean life span of beds in the present study isslightly longer than that in their work. Plumptreand Reynolds4 reported that Budongo forest isdrier than Kibale forest or the forests in Gabon,
and thus it is likely that the leaves that formed thebeds dried up and fell off more quickly. They also
found that mean dry season survival time of beds
was significantly shorter than mean wet season
survival of beds. On the other hand, Wrogemann7
found that bed decay was significantly slower
in dry seasons than in wet seasons in Gabon.
McGrew, Baldwin and Tutin8 placed the Kasoje
area in the next-drier position to Budongo forest
on a wet-dry spectrum. Mean life span of beds inthe present study is slightly longer than that in the
Budongo forest. Consequently, bed decay is notaffected simply by season or rainfall.

12

ACKNOWLEDGEMENTS

The field work was financed by the Monbusho
International Scientific Research Program (07041138
to Toshisada Nishida). The research was facilitated by
the Tanzania Commission for Science and Technology(COSTECH), the Serengeti Wildlife Research Institute(SWRI), the Tanzania National Parks (TANAPA), theMahale Mountains Wildlife Research Centre (MMWRC),and the Mahale Mountains National Park (MMNP).
Bunde Athumani and Makelele Masayuke assisted in thecensus. Michael A. Huffman, Noriko Itoh, Toshisada
Nishida, Kohshi Norikoshi, and Hitoshi Sasaki madecontributions in the ﬁeld. Fumio Fukuda and Toshimichi
Nemoto helped me in various ways to complete theresearch. To these people and institutions, I give mydeepest gratitude.

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Pan Africa News, 12(1), June, 2005

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Pan Africa News, Vol. 12, No.1
Published in June, 2005
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