A preliminary report on wild gray gibbons (Hylobates muelleri) in Danum Valley, northern Borneo

Yoichi Inoue

Introduction

In March 2001, I made a brief visit to the Danum Valley Conservation Area, Sabah, Malaysia. The purpose of this visit was to find out whether the area was suitable to carry out a more detailed behavioral study on gray gibbons (Hylobates muelleri) at a later date.

Material and Methods

The study site is located in northeastern Borneo, about 80 km west of Lahad Datu in the Sabah State of Eastern Malaysia, Malaysia. Observations were carried out near the Borneo Rainforest Lodge at the northern edge of the Danum Valley Conservation Area (Fig. 1).

borneo1fig2.gif (7197 バイト)
Fig. 1. Trail map of the area around the Borneo Rain Forest Lodge (red arrow). The locations where gibbons were encountered are indicated with red crosses and numbered in chronological order: (1) and (2) 22 March, (3) 23 March, (4) 24 March.

Observations on gibbons were carried out from 22-25 March 2001. Survey walks were carried out daily from 06:00 to 12:00. During the survey walks, I was accompanied by a local guide (Mr Palin, Fig. 2). Whenever possible, I recorded the gibbons' behavior on digital video camera (Sony DCR-PC5) equipped with tele converter lens. In addition, I recorded gibbon song vocalizations on MiniDisk, using a Walkman (Sony MZ-R900) with a sensitive microphone (Sony ECM-MS907). After this pilot study, Mr. Kawamura (Chiba University) advised me that MiniDisc recordings are not suitable for bioacoustic research because the sound is compacted and changed in the process (see also Geissmann, 2001). Analog audio or DAT technologies offer a better alternative. Thus, I used a DAT Walkman (Sony TCD-D100) during later visits (see Inoue, 2001).

PALIN.jpg (35947 ノoノCノg)
Fig. 2. Mr Palin, my guide

A summary of gibbon observations

22 March, 2001:

We searched for gibbons in the area west of the Lodge. At 06:10, we encountered one gibbon (observation point 1, Fig. 1), but the gibbon fled almost immediately. After this sighting, we went to the Hornbill trail north of the Lodge. At 10:04, we briefly sighted another gibbon there (point 1, Fig. 1). There was heavy rain in the afternoon.

23 March, 2001:

At 05:58, I heard a male gibbon singing on the oposite bank of the Danum River, west of the Lodge. I approached the singer, and at 06:30, I sighted the singing gibbon (point 3, Fig. 1). No other gibbons were observed in hte surroundings.

button_sound.gif (231 バイト) Click this button in order to hear several phrases of this male solo song bout (mp3 file, duration about 1 minute).


I lost sight of the gibbon at 07:00. There was heavy rain in the afternoon.

24 March, 2001:

At 05:50, I heard a male gibbon singing near the Lodge. When I approached the singer, I met a family group (point 4, Fig. 1). It consisted of 6 gibbons: one adult pair, three younger individuals, and one infant.

button_sound.gif (231 バイト) Click this button in order to hear several phrases of this male solo song bout (wav file, duration about 2 minutes).


This song bout continued until 06:17. After singing, the gibbons ate some fruits and then moved to the next tree at 08:00. At 08:15, one gibbon urinated (Fig. 3) and defaecated (Fig. 4).

ヌョヌオヌ。ヌア.jpg (32182 ノoノCノg) ヌァヌメヌ・jpg (24087 ノoノCノg)
Fig. 3. Gibbon urinating. The arrow indicates the urine. Fig. 4. Gibbon defaecating. The arrow indicates the falling faeces.

After this, the group visited several other trees in a row. At 08:58, I observed one gibbon drinking water from a treehole by dipping its hand into the water (Figs. 5-6).

迴鰺ヌ賀ヨヌ壁・どァ.jpg (21853
ノoノCノg) 迴鰺ヌ賀ヨヌ歩佗゙.jpg (23277
ノoノCノg)
Fig. 5. Gibbon dipping the left hand in the water of a tree hole. Fig. 6. Gibbon drinking water from the fur on the back of its hand.

I lost sight of the gibbons at 10:00.

It rained in the afternoon. In the evening, cicadas produced a very loud chorus at around 18:30.

button_sound.gif (231 バイト) Click this button in order to hear an excerpt of the cicada chorus (wav file, duration 46s).

25 March, 2001:

From 06:40 to 09:00, we searched for gibbons in the forest south of the Lodge but had no success. It was very misty in the forest (Fig. 7).

ナ症テ鷙.jpg (22299 ノoノCノg)
Fig. 7. A misty morning in the forest.


A preliminary report on wild gray gibbons (Hylobates muelleri) in Danum Valley, northern Borneo, part 2

Additional gibbon photographs

All photographs on this page were taken of the the family group encountered on 24 March 2001.

・ヌゥヌチ・ヌレヌ-燻ヌネ.jpg (20091 ノoノCノg)
Fig. 8. Gibbon moving from one tree to the next.

・ヌテ鯀ヌ暮ハヌホヌァヌ隻・ネ.jpg (26592 ノoノCノg)
Fig. 9. Gibbon collecting fruits.

・ヌテ闢ヌゥヌチヌアヌヌチヌ募ゥヌネ.jpg (17079 ノoノCノg)
Fig. 10. Male gibbon watching me intently.

・ヌテ闢ヌ寡?ヌテヌ壁ャヌゥヌヌ管「ヌ・jpg (23069 ノoノCノg)
Fig. 11. Gibbon standing up to catch a branch above him.

・ヌテ闢ヌ臥ソヌネノeノiノK.jpg (20943 ノoノCノg)
Fig. 12. Gibbon resting with it's elbow on the knee.

・ヌテ闢ヌ管・フヌ。ヌ淺アヌヌチヌ募ゥヌネ.jpg (17788 ノoノCノg)
Fig. 13. Gibbon resting.


A preliminary report on wild gray gibbons (Hylobates muelleri) in Danum Valley, northern Borneo, part 3

Additional photographs from Danum Valley

I saw extensive palm tree plantations during the flight to Lahad Datu (Fig. 14) and teak trees along the road leading to the Borneo Rainforest Lodge (Fig. 15). The last Bornean rainforests are continuously being reduced in size because of logging. Along with these forests, the gray gibbon will also disappear. The future of the gibbons and of all other inhabitants of the Bornean rainforests depends on the maintenance of this unique habitat.

palmtree.jpg (48040 ノoノCノg)
Fig. 14. Palm plantation near Danum Valley.

ノ`ナ[ノNヌテ鵞・.jpg (20232 ノoノCノg)
Fig. 15. Teak tree plantation along the road leading to the Borneo Rainforest Lodge.

・鵈・ヌテ・虔.jpg (19242 ノoノCノg)
Fig. 16. Secondary forest along the road to the Lodge.

ノ_ノiノ・oノ蠻[・ヌヒ蝴.jpg (40114 ノoノCノg)
Fig. 17. Primary forest near the Lodge.

ノqノ睨Eヌテ・・.jpg (16719 ノoノCノg)
Fig. 18. Foot print of a clouded leopard (Neofelis nebulosa)

ノgノJノQ.jpg (21880 ノoノCノg)
Fig. 19. Lizard

ノJノGノ・jpg (11138 ノoノCノg)
Fig. 20. Frog

Acknowledgement

I thank Dr.Thomas Geissmann (Institute of  Zoology, Hannover, Germany) for his help in constructing these pages.

Refernces

Geissmann, T. 2001: How to tape-record primate vocalisations. Text available on the website of the Gibbon Network (http:www.gibbons.de). A printable version of the text (in PDF format) can also be downloaded there.

Inoue, Y. 2001: Behavioral observations of wild gray gibbons (Hylobates muelleri) in northern Borneo. Text available on this website.


To main page

inserted by FC2 system