HOPE Report  2004-11-04

Program No.12 (Joint research)

Name: Tomoko Kanamori

Occupation: Doctor Course student, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology.

The title: Study on Social Behaviors of Wild Orangutans in Danum Valley, Sabah, Malaysia

Place of visit: Danum Valley Conservation Area, Sabah, Malaysia

Period of visit: 21 June,2004 - 10 October,2004


Contents of research:

I set up a new research area for wild orangutan study at Danum Valley Conservation Area, Sabah, Malaysia. This research area, undisturbed primary tropical rain forest of about 2km2 locates in Danum Valley Conservation Area forest reserve (438km2) established by Sabah Foundation for the research, education and tourism. In my previous preliminary field research in this area, I already found that many wild orangutan habituated to human is living in this area and the density of males was larger than that of females. This time, in order to start the intensive field research on wild orangutan in this area, I conducted preparative field researches of wild orangutan; trail marking, density estimation, individual identification, mapping and identification of their food plants etc.

In August and September, I tried tracing researches of orangutan and conducted census of fallen fruit and nest. In the tracing research, I could record the behavior of the focul animal and food type they ate. Observation interval of was 1min (Altmann, 1974). I could conduct the tracing researches, fruit census and nest census with help of research assistants from Danum Valley Field Center in.

During the research period of 132 hours 52 minutes (17 days), I could observe wild orangutan for 71 hours 29-minute (9 days) in total. The discovery rate of orangutan was one time per 2 days (53. 8%). I could observe eleven individuals in total. They consisted of 5 males (2 flanged males and 3 un-flanged males) and 4 females and 1 infant, 1 juvenile (2 sets are parent and child). Estimated density of orangutan was 5.5 individuals /km2 , very high density. Observation frequency was high especially from July to September, fruit season of this area. The sex ratio seemed much biased for males. The activities budget of 4 individuals observed was as follows; resting (38%), feeding (36%), moving (14%), aggressive behaviors against observer (4%), and lost (7%). Food type observed was fruit (48%), leaves (38%), bark (7%), flower (2%) and others (4%). Since, orangutan of this study area were in high density and well habituated to human, we will be able to collect good quantitative data on their behavior and food by direct observation.


One adult female eats Fruits.

One flanged male takes a rest.

Study area for wild orangutan at Danum Valley Conservation Area

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