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PUMS99:1 UNIVERSITI MALAYSIA SABAH
BORANG PENGESAHAN STATUS TESIS@
J'UDUL: THE DISTRIBUTION AND ABU.NDANCE. OF PR080J'CIS
MON ICEY C NQJ'a l lJ' (arvot-(9) IN (}/IRAMA. /eLIAS' PfNINSUL ;'
Tjazah: SA RJA '" A MfA DA
SF~c;( PENGAJIAN: MEl ~ 0 0 0 - A P A I L ~ 0 05
Saya 0 E £ PAL U 'f M ) P A I'll V f.I A NAT HAN (HURUF BESAR)
menga:"\! mcmbeoarkan tcsis (LPSlSarjanalDolctor Falsafah)· ini.disimpan di Perpusttkun Univecsiti I Malaysia Sabah deng'fln syarat-syant kegunaan scpecti beri1.-ut
II. Tesis adalab ba~lik U~VC:CSi;i Mala)'l!la Sabah. 2. hrpustakaan U niversiti Malaysia Sabah dibcnatkan membuat salinan untuk tujuan pengajian sabaja. 3. Pcrpustakaan dibcna.rbn membuat salinan tcsis ini scbagai bahan pcrtukaran antan institusi peDgajian
tinggi. 4. "Sila tandakan ( I )
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CATA TAN: • Potong yang tidak bcrlccnaan .
(Mcngll1ldungi maldurnat yang berdaIjah keselamatan atau
kepenti!lgan Malaysia scperti yang tetmaktub di dalam AKTA:RAliSlA RASMl1972)
(M::ngandungi maklumat TERHAD yang tclah ditentukaD olch organisasilbadan di maoa penyelidikan dijalankan)
Oisahkan oleh
(TAt\'''DATANGAN PUSTAKAWAN)
D~ HfNP.Yb£fHiARD Nama PenyC\ia
Tarikh: _________ _
•• Iih Icsis ini SULIT &tau TERHAD, sill. lampirkan sural daripada pihak berkua.c;a/organisasi herkc:nUJ'l dcngan mcnyatllkan sclcaJi scb&b dan tcmpoh Icsis ini pcrlu dikdaskan scbagai SULIT danTERHAD.
@ Tesis dimaksudkan scbagai Icsis bagi Iju...ah Doktor falsafah dan Satjana sccara pcnyelidilcan, a!3U disc:rtasi bag; pcncajilU1 SCC2ra Icetja lcul'SIIS dan pcnyelidikan, at au laporan Projclc SlIjana Muda (LPSM).
THE DISTRIBUTION AND ABUNDANCE OF PROBOSCIS MONKEY
(Nasalis larvatus) IN GARAMA, KLIAS PENINSULA
DEEPAL~PANCHANATHAN
TIllS THESIS IS SUBMITTED AS FULFILMENT OF THE REQUIREMENT FOR
THE DEGREE OF SCIENCE
CONSERVATION BIOLOGY
SCHOOL OF SCIENCE AND TECHNOLOGY
UNIVERSITY MALAYSIA SABAH
March 2005
11
DECLARATION
I hereby declare that the thesis is based on my original work except for the quotations and
citations which I have duly acknowledged.
31 March 2005
ALUXMI P ANCHANATHAN HS2002-3536
11I
CERTIFIED BY
Signature
1. SUPERVISOR
(DR. HENRY BERNARD)
2. EXAMINER 1
(PROF MADYA DR. ABDUL HAMID AHMAD)
3. EXAMINER 2
(MADAM ANNA WONG)
4. DEAN
(pROF MADYA DR.AMRAN AHMED)
IV
ACKNOWLEDGEMENT
First and foremost, I would like to extend my heartfelt gratitude to my supervisor, Dr
Henry Bernard for his guidance and help throughout the completion of this thesis. His
patience and time spent following the progress of this thesis from the very beginning is
very much appreciated. His experience and knowledge in the related field is very much
respected and admired.
I would also like to convey my thank you to my course mate, Miss Y oges who
was there with me throughout the sampling sessions. Not forgetting my friends, Miss
Kavin Mullai and Miss Vickneswary, who assisted us during the second sampling session.
I would also like to thank my friends Miss Kayalvizhi, Miss Deepashini, Miss Kael ViIi
and Miss J asvin for their kind support.
Another important person I would like thank is Miss Siti Sarah, a post-graduate
student in the Institute of Tropical Biology and Conservation for playing the role of an
elder sis during the sampling sessions. Her help and guidance will not be forgotten. I
would also like to extend my gratitude to Mr Sikula, who provided help with the maps of
the Garama area. Not forgetting Encik Awang Mahsis and his family, who took care of
my welfare during my sampling sessions in Garama.
I would like to thank my roommate, Miss Norizan who provided great help in
times of misfortune which struck me during the peak of completing this thesis.
Last but not least, I would like to thank my family for providing moral support
and help by looking for articles and additional information on the species.
v
ABSTRACT
A study on the distribution and abundance of Proboscis Monkey (Nasalis larvatus) was
undertaken at Garama, central part of Klias Peninsula on the west coast of Sabah. Two
sampling sessions were conducted for this study. For the fust sampling session, a five day
survey was carried out from 9 to 13 August 2004 and the second sampling session was
conducted from 17 to 20 December 2004. Census survey along watercourses was done
from a boat and total distance of 33.3 km along 5 main rivers in Garama was surveyed.
The overall estimated population density of N. larvatus in Garama was 0.84 groups/km2
or 6.33 individualslkm2• Nasalis larvatus populations were not uniformly distributed in
Garama. Mangrove forests and peat swamp forests were the major habitat types where
N larvatus was observed. The animal was not observed in village areas and agricultural
lands. The survival of N larvatus populations in Garama was affected by factors related
to human activity. illegal hunting, habitat destruction and fragmentation and unmonitored
wildlife based tourism were among the threats faced by N larvatus in Garama.
Recommendations related to N. larvatus population conservation and management
includes the establishment of protected areas in Garama, public education on conservation
issues of this species, monitoring of wildlife based tourism in Garama and frequent
studies on the population density of this anima1.
VI
ABSTRAK
Satu kajian untuk menentukan taburan dan kelimpahan Monyet Belanda (Nasalis larvatus)
telah dijalankan di Garama yang terletak di bahagian Pantai Barat Daya Negeri Sabah.
Dua sesi persampelan telah dijalankan dalam kajian ini. Bagi sesi persampelan pertama,
tinjauan selama lima hari telah dibuat dari 9 hingga 13 Ogos 2004 manakala sesi
persampelan kedua telah dijalankan dari 17 hingga 20 Disember 2004. Tinjauan
dijalankan dengan menggunakan bot merentasi sungai-sungai di kawasan kajian. Jumlah
jarak yang dilalui ialah 33.3 Ian merentasi 5 sungai utama di Garama. Anggaran
kepadatan keseluruhan N. larvatus yang diperoleh daripada kajian ini 0.84 kumpulan/km2
atau 6.33 individulkm2• Populasi Nasalis larvatus tidak tertabur secara sekata di Garama.
N. larvatus paling kerap ditemui di hutan paya bakau dan hutan pinggir sungai. Monyet
ini tidak dijumpai di kawasan kampung dan kawasan perladangan. Kemandirian populasi
N. larvatus di Garama dipengaruhi oleh faktor-faktor berkaitan dengan aktiviti manusia.
Pemburuan tak terkawal, pemusnahan dan fragmentasi habitat dan pelancongan
berkonsepkan hidupan liar yang tidak terkawal merupakan antara ancaman kepada
populasi N. larvatus di Garama. Cadangan berkaitan dengan pemuliharaan dan
pengurusan populasi N. larvatus termasuk pengiktirafan kawasan perlindungan di Garama,
menyedarkan orang awam tentang isu-isu pemuliharaan spesis ini, pemonitoran aktiviti
pelancongan berkonsepkan hidupan liar and memperbanyakkan kajian yang melibatkan
density populasi monyet ini.
CONTENTS
DECLARATION
APPRO V AL OF EXAMINERS
ACKNOWLEDGEMENT
ABSTRACT
ABSTRAK.
LIST OF CONTENTS
LIST OF TABLES
LIST OF FIGURES
LIST OF SYMBOLS
CHAPTER! INTRODUCTION
1.1 Introduction 1.2 Objectives of study
CHAPTER 2 LITERATURE REVIEW
2.1 Systematic Classification of N larvatus 2.2 Morphological Features 2.3 Distribution and Habitat 2.4 Social Organization 2.5 Daily Activity Patterns 2.6 Feeding Ecology 2.7 Conservation Status
Page
11
III
IV
V
VI
Vll
IX
X
Xl
1 3
4 5 6 9 9 10 11
Vll
CHAPTER 3
CHAPTER 4
CHAPTERS
CHAPTER 6
3.1 3.1.1 3.1.2 3.2 3.3
4.1 4.2 4.3 4.4 4.5 4.6
5.1 5.2 5.3
REFERENCES
APPENDIX
METHODOLOGY
Study Area Census Survey Mapping Distribution Estimating Population Density Statistical Analysis
RESULTS
Weather Conditions during Samplings Sightings of N. larvatus Groups Habitat Selection Types of N. larvatus Group Sighted Distribution of N. larvatus in Garama Abundance of N. larvatus in Garama
DISCUSSION
Distribution Abundance Conservation Management and Recommendations
CONCLUSION
14 19 21 21 22
23 24 25 26 27 31
34 35 37
41
43
47
Vlll
Table number
4.1
4.2
4.3
4.4
LIST OF TABLES
The length of rivers surveyed during the study of N larvatus in Garama
Mean sighting distance and its standard deviation for the first and second sampling sessions.
Population size and population density of N larvatus along the rivers surveyed for the first sampling session.
Population size and population density of N larvatus along the rivers surveyed for the second sampling seSSIon.
IX
Page
28
32
32
33
x
LIST OF FIGURES
Figure Number Page
2.1 Recent records of N larvatus in Borneo 7
3.1 Klias Peninsula in the west coast of Sabah (inset) and 15 The location of Garama study area (A)
3.2 The location of the rivers surveyed for the distribution 18 and abundance of N larvatus in Garama
4.1 Frequency of sightings of N larvatus groups in 24 three different weather conditions.
4.2 Number of N larvatus groups sighted in Garama 25 during the first and second sampling session at different hours of day.
4.3 Major habitat types of N larvatus groups 26
4.4 Types of N larvatus group observed during the 27 first and second sampling
4.5.1 Distribution of N larvatus in Garama during the 29 first sampling session
4.5.2 Distribution of N larvatus in Garama during the 30 second sampling session
Xl
LIST OF SYMBOLS
% percent
lan2 kilometer square
m metre
mm milimetre
sp. speCIes
kg kilogramme
cm centimetre
CHAPTER 1
INTRODUCTION
1.1 Introduction
Borneo Island is home to many unique species of flora and fauna. Sabah, which occupies
the northern part of Borneo Island, is rich in ten primate species, including species that
are considered endangered and vulnerable to extinction such as the Orang Utan (Pongo
pygmaeus) and Proboscis Monkey (Nasalis larvatus) (Cowlishaw & Dunbar, 2000).
In the tropical rain forest ecosystems, many primate species perform important
ecological functions. Pongo pygmaeus, for example is a seed disperser in its natural
habitat (Galdikas, 1982). Nasalis larvatus plays an important role in maintaining
vegetation diversity (Yeager, 1989). By feeding on young leaves and seeds of the most
dominant tree species in its habitat, N. larvatus gives a constraint to the reproductive
success of the dominant tree species, thereby allowing other less dominant or rare tree
species to grow (Yeager, 1989).
2
Many large animals are significant tourist icons. Nasalis larvatus is a popular
tourist attraction because this species is highly visible and spectacular in appearance.
Nasalis larvatus is probably the only species of primate with very long, pendulous nose
that overhangs the mouth (Bennett & Gombek, 1993). This species is also an important
national heritage as it is endemic to Borneo.
Studies on the ecology and behaviour of Nasalis larvatus were carried out
extensively at few places only, examples at the Samunsam Wildlife Sanctuary in Sarawak
(Bennett, 1986), Tanjung Puting National Park in Kalimantan Tengah, Indonesia (Yeager
& Blondal, 1990) and Lower Kinabatangan in Sabah (Boomatana, 2002). An extensive
survey on the general distribution pattern of this species was undertaken by Meijaard &
Nijman (2000) throughout Borneo. In addition, several short term studies have also been
conducted by Bernard (1997, 2005) in Klias Peninsula, Sabah. Bernard (1997) studied the
distribution and abundance of N. larvatus in Klias Peninsula. Such studies have provided
useful information on the behaviour and ecology, as well as on the current distribution of
the species. These are needed for managing populations of endangered species with the
main aim of preventing them or to ensure their long term survival in the wild.
3
1.2 Objectives
The present study, which was conducted in Garama, located at the Klias Peninsula in the
west coast of Sabah, is aimed at determining the current population status of
Nasalis larvatus. The specific objectives are to determine (1) the distribution of N
larvatus in Garama, Klias Peninsula; (2) the relative abundance of N larvatus in Garama,
Klias Peninsula; (3) the threats faced by N larvatus in Garama, Klias Peninsula.
CHAPTER 2
LITERATURE REVIEW
2.1 Systematic Classification of Nasalis larvatus
The Order Primates are characterized by the adaptations for increased agility in arboreal
habitats, omnivorous diets, unspecialized teeth, grasping digits, freely movable limbs,
nails on digits, reduced nasal cavity, enlarged eyes and cerebral hemispheres (Miller &
Hadey, 2002). There are three super families in this order; (1) Ceboidea or 'New World
Monkeys', (2) Cercopithecoidea or ' Old World Monkeys' and (3) Hominoidea (apes and
humans) (Strier, 2003). Cercopithecidae is divided into two subfamilies; Cercopithecinae,
which is omnivorous, and Colobinae, which is herbivorous (Cowlishaw & Dunbar, 2000).
Nasalis larvatus is a colobine monkey (Bennett & Gombek, 1993). The colobines are
unique among the primates in possessing a specialized sacculated stomach, which is
divided into pouch like sections where leaves and in some cases, highly toxic seeds, can
be digested by bacteria living in the gut (Strier, 2003).
Within the colobines, N larvatus belong to the ' odd-nosed' group of monkeys,
whose members are limited to China, Indochina and South-east Asia (Davies & Oates,
5
1994). This is a loose association of species (Bennett, 1986). Nasalis larvatus does not
have close relatives. This monkey is considered to be the only species in the genus
Nasalis. The most closely related species to N larvatus is the Simakobu Monkey (Simias
con color) of the Mentawai Islands, which a few authors classify as Nasalis concolor.
Initially, two subspecies of proboscis monkey were described, Nasalis larvatus larvatus
and Nl. orientalis. However, these are no longer considered valid and all proboscis
monkeys are now thought to belong to a single subspecies (Bennett, 1986).
In Sabah, N larvatus is known by several names, including rasong, bengkatan
and monyet Belanda (or 'Dutchman' monkey) (Payne, 1982). Their enormous, bloated
stomachs and huge pendulous nose have given rise to the name 'Dutchman monkeys' as
the animals somehow reminded people in Borneo of Europeans (Bennett & Gombek,
1993).
2.2 Morphological Features
Nasalis larvatus has a high degree of sexual dimorphism (Bennett, 1986), where males
and females can be distinguished morphologically, particularly in body size (Richard,
1985). Nasalis larvatus are large monkeys. Adult males are known to reach up to 20 kg in
weight and females about half this weight (Rod & Preston, 1999). Adult N larvatus
males can grow a body length of 75 cm, which is measured from top of the head to the
base of the tail and a tail length of 67 cm. The body and tail length of the adult females of
this species is 62 cm and 57 cm respectively (Hofer, 1994). Adult males have an enlarged
6
pendulous nose, which is its most distinct feature, whereas the females have short and
stubby noses (Bennett & Gombek, 1993). Adult males have darker cap over the top of
their heads, yellow collars and thick brown mane of fur. Females are mainly reddish
brown with flesh coloured faces. The rump patch and tail of male N larvatus are pure
white, whereas in females, these are either off-white or grey (Bennett & Gombek, 1993).
Both sexes have partially webbed hind feet which are thought to aid in swimming and
walking on mangrove mud (Bennett, 1986). Nasalis larvatus are known to swim in rivers
within mangrove forests near coastal areas (Bennett & Gombek, 1993).
New-born N larvatus are covered with sparse, blackish fur with stubby upturned
noses (Bennett & Gombek, 1993). The face is dark blue (Bennett, 1986). The fur turns
brown quickly and roughly the same colour of an adult's when the monkey is four months
old.
2.3 Distribution and Habitat
Nasalis larvatus is endemic to the island of Borneo (Payne et. aI., 1985). This species is
found in the four regions of Borneo, i.e., Kalimantan (Indonesia), Sabah and Sarawak
(Malaysia) and Brunei (Figure 2.1). In Kalimantan, N larvatus is found to occur at the
downstream parts of essentially all major rivers and severa] upstream areas (Meijaard &
Nijman, 2000). Nasalis larvatus are widely distributed along the western and far north
eastern parts of Sarawak though their distribution is patchy (Bennett, 1986). In Brunei,
this monkey occurs along the Brunei Bay and the mangrove areas of Pulau Berambang
Banjermasin Central Kalimantan - -- .-
100 a 100 200 Kilometers
Legend
e Recent Records of Proboscis Monkeys
WZJ Protected Areas in Borneo
7
East Kalimantan
Figure 2.1 Recent records of N. larvatus in Borneo (Adapted from Meijaard and Nijman, 2000) .
8
(Yeager, 1995). In Sabah, major populations of this monkey are found on the east coast
particularly around the Dewhurst Bay area and along some parts of the Kinabatangan,
Segama and Sugut rivers (Bernard, 1997). In the west coast of Sabah, a small and patchily
distributed population is found in the Klias Peninsula (Bernard, 1997). Populations have
also been recorded at Sungai Rampayan within the Tempasuk plain in Kota Belud
(Bennett, 1986). Berhala and Sebatik Islands are the only two islands known to support
populations of N larvatus (payne et. aI., 1985).
Based on many observations, breeding populations of N larvatus are mainly
located in coastal forests, including riverine, peat swamp and fresh water swamp forests
(Meijaard & Nijman, 2000). These habitats have different zones with different types of
vegetation that occur patchily depending on distance from the coast or centre of the peat
swamp (Bennett, 1986). These monkeys are found in most of these forest zones, though it
is uncommon to find them in mixed nipah mangroves. This is attributed to the scarcity of
edible plant parts for these monkeys as compared to riverine and mangrove forests
(Bernard, 1997). Populations are occasionally found much further inland but always next
to major rivers such as the Segama and the Kinabatangan in eastern part of Sabah and at
Barito in Kalimantan (Bennett & Gombek, 1993). Solitary males have been recorded in
other forest types many kilometers away from any mangrove or large river. For example,
nomadic animals were seen briefly passing through the dipterocarp forests in the interior
of Sarawak (Bennett, 1986).
9
2.4 Social Organization
The basic social unit of N larvatus is a harem. This comprises an adult male, several
females and their offspring. The average size of a harem is nine animals (Rajanathan &
Bennett, 1990). Different harems frequently come together, particularly to roost on trees
next to rivers in the evening (Bennett & Sebastian, 1988). More than two groups
frequently sleep near to each other (Yeager, 1991). Groups of N .larvatus also meet
frequently during the day (Bennett, 1986). Juvenile males leave their natal group at a
young age to join loosely-organized and unstable all-males groups (Rajanathan &
Bennett, 1990). This all-male group also consists of one or two large males with several
small ones (Boonratana, 2002). Individuals within the same group are loosely bonded and
exchanges of members between groups can occur, particularly adult females (Rajanathan
& Bennett, 1990). Apart from harem and all-male groups, N larvatus is known to form a
third group referred to as non-breeding groups, which is dominated by males with at least
one female member (Boonratana, 2002).
2.5 Daily Activity Patterns
Nasalis larvatus have a peculiar habit of sleeping in trees adjacent to rivers every single
night (Bennett & Gombek, 1993). In the early mornings, animals usually go into the
forest away from the river in search of food. These monkeys do not often travel more than
600 m from the river because they often return to the river edges every evening. The
10
general home range size of N larvatus is a strip of 600 m forest along both sides of the
river (Bennett & Gombek, 1993).
2.6 Feeding Ecology
Feeding usually occurs at heights ranging from 1 m above ground to the crowns of mid
and upper canopy tree (Salter et. al., 1985). Nasalis larvatus are highly selective feeders
(Bennett, 1986). Unripe fruits, seeds and young leaves are usually the main food items
eaten (Yeager & Kirkpatrick, 1998). Fruits eaten are generally not sweet and succulent
but dry and bitter-tasting (Bennett & Sebastian, 1988). Nasalis larvatus do not feed on
ripe fruits because being colobine, they have specialized multi-chambered stomach and
large intake of simple sugars may cause hyperacidity of fore stomach fluid which is lethal
to the monkey (Bernard, 1997). In addition, some plants contain chemicals which can kill
the bacteria in their stomachs (Bennett & Gombek, 1993). Tree families whose seeds are
favoured by N larvatus are Leguminosae and Myristicaceae (Bennett & Sebastian, 1988).
Dipterocarpaceae, Rhizophoraceae and Sapotaceae are the best represented families of
plant species eaten by these monkeys (Salter et. al., 1985). Nasalis larvatus has the ability
to switch dietary strategies during times of low food abundance, where they start using
resources which may be poorer in nutrient quality but widely available like mature leaves
(Yeager, 1989).
11
2.7 Conservation Status
Nasalis larvatus is considered 'vulnerable' according to the mCN threat criteria
(Meijaard & Nijman, 2000) and is listed on Appendix 1 of both the Convention on
International Trade in Endangered Species (CITES) and US Endangered Species List
(Marsh & Mittermeier, 1996). Therefore, it is illegal to move this animal between
countries for commercial purposes and import permits are only given for scientific or
conservation reasons (Bennett & Gombek, 1993). Nasalis larvatus is also rated as a
'highly threatened' species in Sabah, according to the priority ratings of surveys for
specific primate populations in Asia (Eudey, 1987). In Sabah, this species is listed under
Schedule 1 Part 1 of the Wildlife Conservation Enactment 1997, which makes this
monkey fully protected.
In Kalimantan, N. larvatus population is estimated to be more than 250,000
animals, with less than 5000 animals inside protected reserves (Meijaard & Nijman,
2000). There are around 16 conservation areas in Kalimantan, where seven areas are
partially included in the protected area network system. In four of these areas,
conservation measures seem to be completely inadequate for the long-term protection of
the N. larvatus populations. The areas are Pulau Kaget, Tanjung Puting National Park,
Kutai National Park and Kendawangan Nature Reserve where these monkeys are facing
threats like insufficient food resources, habitat loss due to illegal logging, gold mining
and forest fires (Meijaard & Nijman, 2000).
12
In Sarawak, these monkeys are protected in the Samunsam Wildlife Sanctuary,
Maludan River, Bako National Park, Sarawak Mangrove Forest Reserve, Semantan
mangroves, Rajang Delta and Limbang-Lawas mangroves (Salter et. at., 1985). About
10% of the total population size of this species is found in officially gazette protected
area. Among the major threats faced by these monkeys are illegal logging and hunting
(Bennett, 1986).
In Brunei, N larva/us is protected in the mangrove areas of Pulau Berambang and
the whole ofPulau Siarau along the Brunei Bay (Bennett, 1986). The Wildlife Protection
Enactment passed in 1978, listed N larvatus as one of the 34 protected species that
cannot be hunted or exported. Brunei has a high level of wildlife protection because the
export of wildlife is never important in Brunei, guns have been prohibited since 1962 and
timber extraction is only allowed in areas allocated by the government (Mittermeier,
1996). Unfortunately, hunting and logging in Sarawak is causing the populations along
the Brunei Bay to decline when these monkeys cross into Sarawak (Bennett, 1986).
In Sabah, major populations of this monkey are found on the east coast
particularly around the Dewhurst Bay area and along the some parts of the Kinabatangan,
Segama and Sugut rivers (Bernard, 1997). In the west coast of Sabah, a small population
of Nasalis larvatus is found in the Klias Peninsula and at Sungai Rampayan within the
Tempasuk plain (Bennett, 1986, Bernard, 1997). A preliminary estimate of the population
of N larvatus in Sabah showed that at least 2000 animals occurred throughout the state
(payne, 1982). Logging of the mangroves for woodchips was widespread that the
43
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and Management. World Wildlife Fund Malaysia, Kuala Lumpur.
Bennett, E.L. and Sebastian, A.c., 1988. Social organization and ecology of Proboscis
Monkeys (Nasalis larvatus) in mixed coastal forest in Sarawak. International
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Bennett, E.L. and Gombek, F., 1993. Proboscis Monkeys of Borneo. Natural History
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Bernard, H, 1997. Some aspects of behaviour and feeding ecology of the Proboscis
Monkey, Nasalis larvatus, based on the brief study in the Klias Peninsula, Sabah.
Borneo Science 3, 65-84.
Bernard, H., 1997. A study on the distribution and abundance of Proboscis Monkey
(Nasalis larvatus) in the Klias Peninsula. The Journal of Wildlife Management
and Research Sabah 1, 1-12.
Boonratana, R , 2002. Social organization of proboscis monkeys (Nasalis larvatus) in the
Lower Kinabatangan, Sabah, Malaysia. Malayan Nature Journal 56, 57-75.
Cowlishaw, G. and Dunbar, R, 2000. Primate Conservation Biology. The University of
Chicago Press, United States of America.
Davies, AG. and Oates, J.F., 1994. Colobine Monkeys: Their Ecology, Behaviour and
Evolution. Cambridge University Press, Great Britain.
44
Budey A.A., 1987. Action Plan/or Asian Primate Conservation: 1987-91. University of
California, Riverside.
Galdikas, B.M.F., 1982. The Orang Utan: Its Biology and Conservation. Kluwer
Academic Publishers, Netherlands.
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Sheena James, Sailun Hj. Aris, Maklarin Hj. Lakim, Agung Daudi Seventri, Selly
Sitha Sariningsih and Ancrenaz, M., 2003. A boat survey of primates in the Lower
Kinabatangan Wildlife Sanctuary. Lower Kinabatangan Scientific Expedition
2002. University Malaysia Sabah, Malaysia.
Marsh, C.W. and Mittermeier, RA., 1987. Primate Conservation in the Tropical Rain
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