Pan Africa NewsThe Newsletter of the Committee for the Careand Conservation of Chimpanzees, and the Mahale
Wildlife Conservation Society
ISSN 1884-751X (print), 1884-7528 (online) mahale.main.jp/PAN/

JUNE 2015
P. A. N. EDITORIAL STAFF
Chief Editor:
Kazuhiko Hosaka, Kamakura Womenʼs University, Japan
Deputy Chief Editor:
Michio Nakamura, Kyoto University, Japan
Associate Editors:
Christophe Boesch, Max-Planck Institute, Germany
Jane Goodall, Jane Goodall Institute, USA
Tetsuro Matsuzawa, Kyoto University, Japan
William C. McGrew, University of Cambridge, UKJohn C. Mitani, University of Michigan, USA
Vernon Reynolds, Budongo Forest Project, UK
Yukimaru Sugiyama, Kyoto University, Japan
Richard W. Wrangham, Harvard University, USA
Takeshi Furuichi, Kyoto University, Japan
Editorial Secretaries:
Noriko Itoh, Kyoto University, Japan
Koichiro Zamma, Kyoto University, Japan
Agumi Inaba, Mahale Mts. Chimpanzee Research Project
Eiji Inoue, Kyoto University, Japan
Instructions for Authors:
Pan Africa News publishes articles, notes, reviews,
forums, news, essays, book reviews, letters to editor, andclassified ads (restricted to non-profit organizations) on any
aspect of conservation and research regarding chimpanzees(Pan troglodytes) and bilias (Pan paniscus). Contributors arerequested to write in English and the papers except forums,
reviews and essays should usually be 1,500 words or less.
Articles, notes and reviews will be peer-reviewed by at least one
appropriate expert on request of the PAN editorial staff.
PAN is published twice a year in June and December.
Deadline for manuscripts is two months before publication (i.e.
the ends of April and October). Submit your manuscripts via
email to pan.editor@gmail.com.

VOL. 22, NO. 1

Contents<NEWS>
Mahale Research 50th Anniversary
Kazuhiko Hosaka 				
2<NEWS>
Mahale 50 Book Coming Soon
Michio Nakamura, Kazuhiko Hosaka,
Noriko Itoh & Koichiro Zamma		
3<NOTE>
Photos from the Pioneer Period of Mahale
Michio Nakamura(photographs by Toshisada Nishida)
4<NOTE>
Root Eating by Wild Chimpanzees (Pan troglodytes) in
the Kalinzu Forest, Uganda: Possible Medicinal Plant
Use
Natsumi Aruga, Hodaka Matsuo,
Takeshi Furuichi & Chie Hashimoto
7<NOTE>
Association of a Young Emigrant Female Bonobo during an Encounter with her Natal Group
Kazuya Toda, Tetsuya Sakamaki,
Nahoko Tokuyama & Takeshi Furuichi		10• Manuscripts: Format as DOC or RTF files• Photos and figures: Format as JPEG or GIF files. Do NOT
paste on Word files or create as PDF files. Figures could besent as excel files also.
• Audiovisual data: Authors could include audiovisual data toenhance their papers, although they will be included in the
online version only. Sound or video files should be sent only
after communicating with the editor to obtain more detailed
instructions.
• Send these separately by e-mail attachments.
See also http://mahale.main.jp/PAN/instruction.html.
Deadline of the next issue is October 2015!

1

Pan Africa News, 22(1), June 2015

2

<NEWS>

Mahale Research 50th
Anniversary

to study wildlife in ‘Greater Mahale’—covering a wide
area including Mahale and Ugalla—is also ongoing for
an integrative understanding of regional biodiversity,
which is essential in terms of conservation strategies.

Kazuhiko Hosaka
Co-chairman, Mahale Wildlife Conservation Society,c/o Kamakura Women’s University, Japan(E-mail: hosaka@kamakura-u.ac.jp)

A half century has passed since Junichiro Itani andhis students met in September 1965 at the Kasakati Basinand decided to embark on a challenge of habituatingwild chimpanzees of the Mahale Mountains (Itani 1970).
Mahale had been a prospective candidate site for a longterm chimpanzee research since Itani went on his first
expedition to Tanganyika in 1960 with Kinji Imanishi, his
predecessor as the project leader (Itani 1961). However,it took the research team 4 years to reach Mahale until
Kosei Izawa finally visited Kasoje just before the meeting(Izawa 1977). The initial priority of the team was to habituate chimpanzees living in savannah‒woodland areas
to the northeast of Mahale because researchers aimed tolook for clues to understand how human ancestors shifted
their habitats from forested to arid ones (Itani 1970).
Toshisada Nishida successfully habituated chimpanzees by artificial provisioning in July 1966, which was thestart of the second longest-running chimpanzee research
project. The food given to chimpanzees was later reduced
and observational studies have been conducted without provisioning since 1987. The project was joined bymany researchers including Kenji Kawanaka and Shigeo
Uehara, and it has produced numerous scientific findings
concerning the behaviour, ecology, and society of Mahale
chimpanzees, although there is not enough space here to
go into details.
In 1985, Mahale became the 11th national park of
Tanzania, representing triumph for researchers who had
dedicated two decades to research wildlife, especiallychimpanzees, and to protect them from deforestation andother threats to survival. However, at the same time, thebirth of the Mahale Mountains National Park presented
dramatic societal and lifestyle changes for the Watongwe,
indigenous people of Mahale. The Mahale Wildlife
Conservation Society, established in 1994, has contributed
to improvements in education and medical services of thelocal community. We believe that spontaneous involvement of the Watongwe people is crucial for environmental conservation because their ethnicity and traditional
knowledge are closely connected to nature in and around
Mahale.
Recently, the research team has broadened its focus
beyond chimpanzees, partly as an inevitable response tomodern-day demands to conserve ‘biodiversity.’ Leopard
research has been initiated recently, whereas an interest in
diurnal and nocturnal mammals that share habitats withchimpanzees is ongoing. In addition, some researchers,
including Gen’ichi Idani and Hideshi Ogawa are continuing an extensive study regarding savannah-dwelling
chimpanzees in Ugalla; this project was resumed in 1994
by Takayoshi Kano, who participated in a pioneer study
there with Itani in 1966. A collaborative research project

Figure 1. The poster for a public outreach event that willtake place at the Yayoi Auditorium, University of Tokyo on
19 September 2015.

To commemorate the 50th anniversary of the Mahale
Mountains Chimpanzee Research Project, various events
will be held beginning this July. First, the workshop ‘Fifty
years of research on wild chimpanzees: Significance andfuture of long-term research’ will be offered at the 31st
Congress of the Primate Society of Japan in Kyoto on 18
July. Second, ‘Mahale 50: Exhibition and symposium’
will be held as a public outreach event in Tokyo on 19
September (Figure 1). Two new books edited by Mahale
researchers are expected to be released during this event:one is a thick academic volume (in English) by many
researchers who have studied Mahale chimpanzees (announced in this issue for details), and the other—written
in Japanese by Nakamura for general readers—provides
the history of Mahale chimpanzee research. Third, thesymposium ‘A half-century of wild chimpanzee research:
How does long-term wild ape research contribute to anthropology?’ will be held in Tokyo at the 69th Congressof the Anthropological Society of Nippon on 12 October.
Finally, the ceremony to celebrate the 50th anniversary ofinternational collaboration at Mahale is being planned totake place at Kigoma, Tanzania—perhaps in November.

Pan Africa News, 22(1), June 2015
The next issue of Pan Africa News will include reviews ofsome of these events.

References

Itani J 1961. [The Forest of Gorillas and Pigmies.] Iwanamishoten, Tokyo, in Japanese.
Itani J 1970. [In the Pursuit of Chimpanzees.] Chikumashobo, Tokyo, in Japanese.
Izawa K 1977. [The chimpanzees of the Kasakati Basin, II.]
In: [The Chimpanzees.] Itani J (ed). Kōdansha, Tokyo, pp.
187‒248, in Japanese.

<NEWS>

Mahale 50 Book Coming Soon
Michio Nakamura1, Kazuhiko
Hosaka2, Noriko Itoh1 & Koichiro
Zamma31 Wildlife Research Center, Kyoto University, Japan
2 Kamakura Women’s University, Japan
3 Graduate School of Asian and African Area Studies, Kyoto
University, Japan(E-mail: nakamura@wrc.kyoto-u.ac.jp)

We are happy to announce here that we are finalizing a book, Mahale Chimpanzees: 50 Years of Research,which will soon be published from the Cambridge
University Press (the publication is due in September2015). Publication of this volume was planned in order tocompile the research achievements that have been accumulated after half a century of research at Mahale.
As readers of Pan Africa News are well aware, thelate Prof. Toshisada Nishida, the founder of chimpanzee
research at Mahale, published a monograph on Mahale’s
chimpanzees, titled Chimpanzees of the Lakeshore(Nishida 2012). In the book, he described various episodes of his research life in Tanzania together with several important academic topics to which he dedicated his
research career. However, the book was not intended tocomprehensively cover the research topics investigatedby other researchers at Mahale. Actually, he wanted toedit an encyclopedic volume about Mahale, which would
complement his personal account. In the special issue of
Pan Africa News, Emeritus Prof. Masao Kawai wrote as
follows:“Furthermore, he was preparing to compile all his
longtime accomplishments into a lifework English language volume. I can hardly imagine how deeply he regretted having to go on his last journey without realizing suchplans.” (Kawai 2011)
We, therefore, pursued his goal, making use of the apt
opportunity of the 50th year of research at Mahale.
This coming book takes the form of an edited volume, composed of 50 chapters and seven appendices by atotal of 24 authors. Each chapter summarizes the researchoutcomes that have been made from Mahale in addition to
new unpublished data. Thus, with this single volume thereader will easily get access to the key information pub-3
lished from Mahale. We also focused on the accumulationof the research effort of 50 years, thus, highlighting longterm changes in behavior wherever possible.
This is the four th academic edited volume on
Tanzanian chimpanzees by the Japanese research team.
The former three volumes were published in 1977 (Itani
1977), 1990 (Nishida 1990), and 2002 (Nishida et al.
2002), respectively. This means each time span between
publications is 12–13 years. The first and the third ones
are in Japanese and the second and upcoming fourth ones
are in English. Among 24 authors in the upcoming volume, none had contributed to the first book: By the time,none had yet started their careers as researchers, most ofthem were still in their childhood, and some were evennot born yet! This shows how the current of time is.
Through compilation of the research outcomes overthese 50 years, we have learned that we still have much
more to know about chimpanzees. The research must go
on. We hope this upcoming volume will facilitate evenyounger people to get interested in chimpanzees. In order
to continue the Mahale research for another 50 years, wedefinitely need involvement of the younger generation.

REFERENCES

Itani J (ed) 1977. [The Chimpanzees.] Kōdansha, Tokyo, inJapanese.
Kawai M 2011. The passing of Professor Toshisada Nishidalamented. (translated by Hosaka K). Pan Afr News 18(special issue):1–2.
Nishida T (ed) 1990. The Chimpanzees of the Mahale
Mo untain s: S e x u al an d Life Hi stor y S t rateg ie s.
University of Tokyo Press, Tokyo.
Nishida T 2012. Chimpanzees of the Lakeshore: Natural
History and Culture at Mahale. Cambridge University
Press, Cambridge.
Nishida T, Uehara S, Kawanaka K (eds) 2002. [The Mahale
Chimpanzees: Thirty-Seven Years of <Panthropology>.]
Kyoto University Press, Kyoto, in Japanese.

Pan Africa News, 22(1), June 2015

4

<NOTE>

Photos from the Pioneer Period of
MahaleMichio Nakamura (photographs by
Toshisada Nishida)
Wildlife Research Center, Kyoto University, Japan(E-mail: nakamura@wrc.kyoto-u.ac.jp)

The late Prof. Toshisada Nishida, the founder of theMahale Mountains Chimpanzee Research Project, left
piles of research materials, such as field notes, photographs, videos, research memos, etc. These materials are
precious information sources to know the early days of
Mahale research and the chimpanzees. Nishida was alsointerested in traditional lifestyle of the Tongwe people
who were living at Mahale when Nishida started the research. Thus the materials also includes ethnographic
information of the Tongwe at the time.
The materials are now stored in a room at Wildlife
Research Center, Kyoto University. By a grant from the
Research Resource Archive, Kyoto University, we are
now digitalizing these materials. Due to the large amountof materials and limited budgets, we have started fromolder photographs that were taken in 1960s and 1970s.
Here I would like to show some of such photographs.

Figure 2. Nishida, Takayoshi Kano,
Jun’ichiro Itani, Kosei Izawa andtwo Tanzanian research assistants(from left to right) at Kasakati Camp.
Nishida first went to Kasakati before
starting his research at Mahale.
Taken in 1965.

Figure 4. At Kasakati Research
Camp. Itani is at the center carrying
a gun. Taken in 1965.

Figure 1. A leaf from Nishida’s slide photo files. The mostof color photographs had originally been kept in this way.
Now each slide film is dismounted and kept between asheet in order to avoid oxidization.

Figure 3. At Kasakati Research Camp. Porters, Itani, andKano (from left to right). Taken in 1965.

Pan Africa News, 22(1), June 2015

Figure 5. A boat which was probably used by Nishida
when he first went to Mahale. Taken in 1965.

5

Figure 6. Mahale Mountains viewed from the lakeshore of
the Tanganyika. This photograph was taken on October
13, 1965, thus two days after Nishida’s first arrival to
Mahale.

Figure 7. Tongwe people probably at Kasiha Village at Mahale. They seem to be preparing for traditional dance andmusic. At the time Nishida arrived at Mahale, there still were several Tongwe villages there and people there were
living in traditional way. Taken in 1965.

Figure 9. Chimpanzees of K group at Kansyana feeding
site, taken on August 8, 1967, about a year after the
success of the habituation. This was Nishida’s second
visit to Mahale.
Figure 8. A Tongwe man with a lake fish, probably at
Kasiha Village. Taken on October 13, 1965.

Pan Africa News, 22(1), June 2015

6

Figure 10. Two early Tongwe research assistants,
Issa Kapame Ally (left) and Ramadhani Nyundo(right) beating drums on a boat. Taken on August
11, 1967.

Figure 11. Nishida (left)
and a Tongwe lady. Taken
on November 4, 1968.

Figure 13. Tongwe men in a village. The man in thecenter has a traditional string instrument. Taken on
October 4, 1968.

Figure 12. A Tongwe traditional
instrument. Taken on October 4,
1968.

Figure 14. Chimpanzees at feeding site. Taken on August
15, 1969.

Figure 15. Chimpanzees and Nishida at feeding site. Taken on August 13, 1969. In this year, Nishida had alreadyobtained his doctor’s degree at Kyoto University. Kenji Kawanaka first joined the research in this year.

Figure 16. At Mt. Sibindi. Kawanaka is in
front right. Taken on September 2, 1969.

Figure 17. Tongwe’s traditional artifacts. The leopard
skulls at the tips of dead branches are called nsongole
that displays the location of a Tongwe chief, mwami.
Taken on September 6, 1969.

Pan Africa News, 22(1), June 2015

<NOTE>

Root Eating by Wild
Chimpanzees (Pan troglodytes)
in the Kalinzu Forest, Uganda:
Possible Medicinal Plant Use
Natsumi Aruga, Hodaka Matsuo,
Takeshi Furuichi & Chie Hashimoto
Primate Research Institute, Kyoto University, Japan(E-mail: aruga.223@gmail.com)

Introduction

Although wild chimpanzees mainly feed on ripe fruitand other food items found above the ground (Wrangham
1977; Nishida & Uehara 1983; Goodall 1986), somestudies have reported that chimpanzees feed on roots or
tubers (Nishida & Uehara 1983; Kortlandt & Holzhaus
1987; McGrew et al. 1988; Newton-Fisher 1999; Lanjouw
2002; Morgan & Sanz 2006; Hernandez-Aguilar et al.
2007; Hockings et al. 2010; Watts et al. 2012). Among thechimpanzees observed eating roots or tubers, most wereobserved feeding on underground storage organs (USOs),
and such behavior was mainly observed in drier environments (Kortlandt & Holzhaus 1987; McGrew et al. 1988;
Lanjouw 2002; Hernandez-Aguilar et al. 2007).
Only a few studies have reported feeding on roots
other than USOs. M group chimpanzees of the Mahale
Mountains National Park, Tanzania, bite off and chew
woody roots emerging from the ground (Nishida &Uehara 1983; Itoh & Nakamura in press).Chimpanzeesof the Ngogo community in the Kibale National Park,
Uganda, chew wood from the roots of Neoboutonia macrocalyx and discard the wadge after chewing on them
(Watts et al. 2012). In this study, we report on chimpanzees feeding on wood from the roots in the Kalinzu
Forest, Uganda, and discuss some possible roles of thisbehavior.

7
Methods

We observed the M group of chimpanzees living in
the Kalinzu Forest Reserve, located in western Uganda(0°17′N, 30°07′E ) (Howard 1991; Hashimoto et al.
2001; Hashimoto & Furuichi 2006). M group has been
under observation since 1997 and is habituated to theextent that during the current study period chimpanzees
could be observed at a distance of less than 10 m on the
ground. Complete identification of central individuals
was achieved in 2003. During the current study period,
M group included 15 adult males, 9 adolescent males, 25
adult females, 16 adolescent females, and 36 immature individuals. For individuals other than those who had been
observed since birth, we estimated the age class fromtheir body size according to the standard specified by
Goodall (1986).

ObservationS

Observation 1
On January 3, 2015, at 14:25, TF found an adult female Pinka feeding on a detached piece of root from atree (approx. 30 cm × 3 cm). She repeatedly bit off a piecechewed it, and spat it out. After she stopped feeding on
it and moved away at 14:33, we found a pile of discarded
wadge on the ground (Figure 1). In a small stream approximately 10 m from the place where Pinka was sitting,
we found many pieces of detached root, footprints ofseveral chimpanzees, and tree roots that stuck out fromthe bank of the stream, and showed signs of having been
bitten off (Figure 2). Because many tree roots were sticking out from the stream bank, we could not identify whichtree the roots came from. TF chewed one of the pieces,
but could not detect any particular taste.
Observation 2
On Januar y 6, 2015, at 12:07, NA found Gaia
(10-year-old female) sitting on a branch, eating somethingsimilar to a root. At 12:19, she finished eating it. We could

Figure 1. The wadge Pinka spat out (Photograph by Takeshi Furuichi).

Pan Africa News, 22(1), June 2015

8

Figure 2. The tree roots sticking out from the stream bank showing the bitten-off ends
(Photograph by Takeshi Fruichi).

not identify what she ate because she ate all of it. We did
not observe her spitting any wadge out.
Observation 3
On January 6, 2015, at 14:04, NA found Gale (6-yearold female) and her sister Gaia eating roots of a fallen tree
at the edge of the stream. At 14:08, Gaia climbed up into a
nearby tree with a part of the root. She ate it while sitting
on a branch. At 14:09, Minny (adult female) approachedand started eating roots of the fallen tree with Mizuki(0-year-old offspring of Minny) on her chest. Minny directly bit off a root and chewed it (Video 1: available online atmahale.main.jp/PAN/22_1/22(1)_04.html). At 14:15, Galecame back and started eating a piece of the root with
Minny. At 14:29, Minny pulled out another root from theground, by grasping a part of it that was found on the surface and ate it. At 14:31, Gale spat out a part of the rootthat she was chewing. At 14:37, they finished eating roots.
All leaves of the tree had already fallen, but the bark was
fresh. The tree was identified as Neoboutonia macrocalyx(Eupborbiaceae) from the color and texture of the barkand the smell of the wood. Although we only observed
spitting out of wadge once, we found many pieces ofwadge around the tree (Figure 3).
Observation 4
On January 8, 2015, NA observed Iku (9-year-old
female) and her sister Iyo (5-year-old female) eatingroots. At 13:14, Iku climbed down from the tree. At 13:16,
Iku climbed up the same tree with a piece of root and at
13:17, began to eat it. At 13:18, Iyo approached Iku, andshe took the root from Iku. At 13:19, Iyo started to eat
it. At 13:40, Iyo obtained it back from Iku and moved
away. We did not observe them spitting out wadge material during this observation (Video 2: available online atmahale.main.jp/PAN/22_1/22(1)_04.html).

Discussion

Feeding on roots other than USOs is rare in chimpanzees. The lists of items ingested by chimpanzees atseveral study sites do not mention “root” as a plant parteaten by chimpanzees (Bossou: Sugiyama & Koman
1987 but see Hockings et al. 2010; Mt. Assirik: McGrew
et al. 1988; Kibale: Chemurot et al. 2012), and lists fromother study sites contain only few species of root items
ingested (Kahuzi: 1 species, Basabose 2002; Budongo:
1 species, Fawcett 2000; Ngogo: 3 species, Watts et al.
2012; Mahale: 2 species, Itoh et al. in press). Watts et al.
(2012) have reported that time spent feeding on roots was
only 0.4% of total feeding time. Feeding on roots may berare occurrence because roots are not easily obtainable bychimpanzees. In this study, chimpanzees obtained rootsthat were emerging from the bank of a stream or from afallen tree. In Mahale, chimpanzees bit-off and chewed
roots emerging from the ground (Nishida & Uehara 1983;
Itoh & Nakamura in press). Although chimpanzees wereobserved eating roots that existed under the ground, theyobtained the roots by pulling a portion of the roots thatwas found above the ground (Kalinzu: this study; Mahale:
Itoh & Nakamura in press).
Chimpanzees and gorillas often chew woody roots
or wood pulp material without swallowing it (this study;
Rothman et al. 2006; Reynolds et al. 2009; Watts et al.
2012; Itoh and Nakamura in press). Wood is characteristically highly fibrous, relatively indigestible, and poorin nutrients (Waterman 1984). Therefore, chimpanzees
may chew roots because they contain micronutrientssuch as sodium (Budongo: Reynolds et al. 2009; Bwindi:
Rothman et al. 2006).
Furthermore, it is also possible that chimpanzees eat
roots for medicinal purposes. Huffman (1997) has argued
that live/dry wood feeding by chimpanzees is a possible
form of medicinal plant use. Root eating observed in thisstudy may also be classified as medicinal plant use bychimpanzees. In Kalinzu and Ngogo (Watts et al. 2012),
chimpanzees ate woody roots of Neoboutonia macro-Pan Africa News, 22(1), June 2015

9

Figure 3. There were many pieces of wadge around the roots (Photograph by Natsumi Aruga).

calyx. The stem bark of Neoboutonia macrocalyx has
medicinal properties (Kirira et al. 2007; Namukobe et al.
2014). In fact, local people in Uganda use the stem barkof Neoboutonia macrocalyx to treat stomach ache andmalaria (Namukobe et al. 2011). However, further investigation is required to determine the presence or absenceof bioactive compounds in the roots in the same state as
those being consumed by chimpanzees, and to evaluate
the health status of consumers before and after consumption of root material before assuming further conclusions(Huffman 1997). Our observations provide new evidence
suggesting the need to further evaluate this interesting
behavior in chimpanzees.

Acknowledgements

We thank the National Forestry Authority of Uganda,
Uganda National Council for Science and Technology for
research permits. We thank the research assistants andother workers in Kalinzu for supporting us. Furthermore,
we thank members of the Primate Research Institute (PRI),
Kyoto University, and researchers conducting research on
primates in Kalinzu for various support and encouragement.
This study was financially supported by JSPS Grants-in-Aid
for Scientific Research (40379011 to Hashimoto; 26257408
to Furuichi; 25257495 to Ihobe; 25257407 to Yumoto), theJSPS Asia-Africa Science Platform Program (2012–2014 toFuruichi), and the Leading Graduate Program in Primatology
and Wildlife Science (to Kyoto University).

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Waterman PG 1984. Food acquisition and processing asa function of plant chemistry. In: Food Acquisition
and Processing in Primates. Chivers DJ, Wood BA,
Bilsborough A (eds), Plenum Press, New York, pp. 177–211.
Watts DP, Potts KB, Lwanga JS, Mitani JC 2012. Diet of
Chimpanzees (Pan troglodytes schweinfurthii) at Ngogo,
Kibale National Park, Uganda, 1. Diet composition and diversity. Am J Primatol 74:114–129.
Wrangham RW 1977. Feeding behaviour of chimpanzees inGombe National Park, Tanzania. In: Primate Ecology:
Studies of Feeding and Ranging Behaviour in Lemurs,
Monkeys and Apes. Clutton-Brock TH (ed), London
Academic Press, London, pp. 504–538.

<NOTE>

Association of a Young EmigrantFemale Bonobo during an
Encounter with her Natal Groupbeen well understood why females emigrate from natal
groups in these species. Similarly, proximate factors forfemale transfer remain poorly understood due to the difficulty of successive observations of young females before
and after their transfer. Therefore, more information isneeded on the process of female transfer between groups.
Bonobo societies maintain relatively less antagonistic
relations between groups, and affiliative interactions areobserved between members of different groups during
encounters (Idani 1990; Furuichi 2011). Young females
often migrate between groups during inter-group encounter not only once but also repeatedly (Sakamaki et al. inpress). Association patterns of young females during theencounters should reflect their motivation to emigrate intoanother group or to remain in the current group. Here,
we report observations of a young emigrant female during an encounter between her current group and her natal
group over four successive days. We show the association
patterns and social interactions of the young female withmembers of both groups.

MATERIALS & METHODS

Observations for this study were made at Wamba in
the northern sector of the Luo Scientific Reserve in DR
Congo (Furuichi et al. 1998). Studies at Wamba started
in 1973, but were interrupted from 1996 to 2002 due tothe civil war. Research was resumed in 2003, and one
study group (E1) has been followed on a daily basis since.
Researchers had also observed a western adjacent group(P) until 1996, and observation of this group resumed withintensive habituation on a daily basis in September 2010.
This group was renamed ‘P-east’ (Pe) to differentiate itfrom another western group, ‘P-west’ (Pw). All animals
in Pe group were identified by August 2011. The E1 groupconsisted of 36 animals and the Pe group consisted of 26
animals in August 2014.
A young female (Puffy) was first identified in the Pe
group in November 2010 (Figure 1). From our observa-

Kazuya Toda, Tetsuya Sakamaki,
Nahoko Tokuyama & Takeshi
FuruichiPrimate Research Institute of Kyoto University, Japan(E-mail: toda.kazuya.78x@st.kyoto-u.ac.jp)

INTRODUCTION

Sex-biased dispersal is an almost ubiquitous featureof the life histories of group-living mammals (Handley& Perrin 2007). Most primates resemble other mammals
in showing male-biased dispersal, which is considered
to be related to the fact that female reproductive successis limited primarily by nutritional constraints in mammals where females bear the major burden of investmentof their offspring, such as birth and nursing (Greenwood1980). On the other hand, societies of chimpanzees andbonobos show clear female-biased dispersal: females usually transfer between groups upon reaching sexual maturity (Thompson 2013; Sakamaki et al. in press). Althoughinbreeding avoidance may be a plausible ultimate factor of
sex-biased dispersal in mammals (Pusey 1980), it has not

Figure 1. Puffy in March 2015.

Pan Africa News, 22(1), June 2015

11

Figure 2. Comparisons of per-scan number of animals found in Puffy’s proximity (in 116 scans) between the E1 and Pe
groups. This figure shows how frequently E1 or Pe animals were observed within 1 m or 5 m of Puffy. Error bars show
the standard deviation. We resampled one scan for 30 min (N = 24; 144 scans/6 scans) to avoid auto-correlation andperformed a Wilcoxon signed rank test to examine the difference between the number of E1 animals and that of Pe
animals within 1 and 5 m. There were no significant differences between the number of E1 and Pe members either within
1 m (T = 31, N = 24, n.s.) or within 5 m (T = 70, N = 24, n.s.).

tions, we assumed that an adult female (Pao) was hermother and a female infant (Pipi) was her younger sister.
She was estimated to be 7 years old from her body size
and the inter-birth interval with Pipi, whose age wasestimated at 2 years (the inter-birth interval in bonobos
is considered to be approximately 4.8 years; Furuichi etal. 1998). She emigrated from the Pe group to E1 groupon October 12, 2013 during an encounter between thegroups, and has remained with the E1 group ever since.
The next encounter between the Pe and E1 groups occurred on August 16, 2014, when Puffy met members of
her natal group for the first time since her emigration.
On August 16, 2014, an inter-group encounter occurred in the area that Pe group usually ranged. Puffy
arrived at the area with E1 members. The groups wererepeatedly within sight of each other, and when separated
were usually within earshot until August 19. One of theauthors (KT) recorded the behaviors of Puffy via focal
animal sampling for approximately 3 hours per day during these four days. KT also recorded the identities ofanimals that were observed within 5 m using scan sampling at 5 minute intervals during focal animal observations. A total of 144 scan samples were recorded over fourdays, and we used data from 116 scan samples excluding
28 scan samples when KT lost sight of Puffy from theanalysis (25 samples on August 16, 31 samples on August17, 27 samples on August 18, 33 samples on August 19).
Frequencies of social grooming with Puffy were determined from these scan data. We used the records of animals within 5 m of Puffy to compare the mean number ofanimals in all scans (called “per-scan number” hereafter)
and the actual number of animals on each day (called“all-day number” hereafter) between the E1 group (27animals) and Pe group (23 animals), excluding infants (<4years old). The all-day number was calculated by counting animals found in the proximity of Puffy at least oncein a day.

RESULTS & DISCUSSION

Figure 2 compares the mean number of E1 animals
and Pe animals found in Puffy’s proximity in 116 scans.
In these scans, an average of 0.11 animals from the E1
group and 0.29 animals from the Pe group were foundwithin 1 m of Puffy, while 0.70 animals from the E1
group and 0.53 animals from the Pe group were recorded
within 5 m. A statistical test where we resampled one
scan for 30 min to avoid auto-correlation did not show asignificant difference in the per-scan number between theE1 and Pe members at either distance. Figure 3 compares
the all-day number of animals found in the proximity of
Puffy on each day between the E1 and Pe groups. There
was no difference between the numbers of E1 and Pe
members within 1 m of Puffy. However, while there wereno specific animals among E1 members regularly foundwithin 1 m, two members of the Pe group were very frequently found within 1 m of Puffy (Marie, a young adultfemale: 24 times, 71% of all scan records of Pe animals
in 1 m proximity; and Michio, a juvenile male: 6 times,
18% of all scan records). Puffy exchanged social grooming with these two animals more frequently (11 scans withMarie and 3 scans with Michio out of 16 scans with social
grooming) than with E1 members. On the other hand, 24
animals from the E1 group (89% of all E1 members) and11 animals from the Pe group (48% of all Pe members)
were found within 5 m at least once in all scans (116scans). These results suggest that Puffy ranged more with
E1 members than Pe members during the focal observation. Thus, Puffy appeared to associate with E1 members
rather than Pe members for the four days of the study period, while she had much more frequent grooming interactions with specific animals of her natal group.
Although both Pao and Puffy were observed on all

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Pan Africa News, 22(1), June 2015

Figure 3. Comparisons of the all-day number of animals found in Puffy’s proximity for each day of observation (N = 4days). This figure shows how many E1 or Pe animals were recorded within 1 m or 5 m of Puffy on each day. Error bars
show the standard deviation.

four days, Pao was observed within 5 m of Puffy in only
one of the 116 scans conducted. Puffy was observed interact with Pao on the first day of the group encounter:NT observed that Puffy played with Pao and begged her
for food during ad libitum observation. However, no social interactions between them were observed in focal
observations. These results suggest that neither Puffy nor
Pao paid particularly attention to one another during theobservation. Puffy was frequently observed to associatewith Pao before her emigration in 2013, although she rarely groomed with her. Therefore, the relationship between
Puffy and Pao appeared to have changed gradually before
her emigration.
This was the first observation of an emigrant female
during an encounter with her natal group members at
Wamba. Interestingly, Puffy seemed estranged from her
mother and members of her natal group after 10 monthsof separation although she interacted with some young
animals of her natal group. She may have already become
the member of the E1 group in the 10 months. This observation suggests that Puffy has no motivation to returnto her natal group although it cannot be asserted that thecause is a change of her group identity into the new group.
Habituation of several other groups adjacent to E1 and Pe
is currently proceeding at Wamba. We expect that the accumulation of similar observations will contribute to anincreased understanding of how female bonobos decideon transfers between groups.

ACKNOWLEDGEMENTS

This research was financially supported by the Leading
Graduate program in Primatology and Wildlife Science of
Kyoto University (to KT), the Japan Society for the Promotionof Science (JSPS) Asia-Africa Platforms (to TF), the Japan
Ministry of the Global Environment Research Fund (to TF),
JSPS Grants-in-Aid for Strategic Young Researcher Overseas
Visits Program for Accelerating Brain Circulation (to Primate
Research Institute, Kyoto University), and JSPS HOPE projectof the Primate Research Institute of Kyoto University, JSPS
Research Fellowships for Young Scientist (to NT). We thankthe DR Congo Ministry of Science for permission to conduct

research at Wamba. We also thank the local staff and others at
Wamba for their support during our study.

REFERENCES

Furuichi T 2011. Female contributions to the peaceful natureof bonobo society. Evol Anthropol 20:123–142.
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Greenwood PJ 1980. Mating systems, philopatry and dispersal in birds and mammals. Anim Behav 28:1140–1162.
Handley L, Perrin N 2007. Advances in our understanding of mammalians sex-biased dispersal. Molecul Ecol
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Pan Africa News, Vol. 22, No.1
Published in June, 2015
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ISSN: 1884-751X (Print), 1884-7528 (Online)