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
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