OnLine Journal of Biological Sciences

Summarizing Spatial Distribution Density, Movement Patterns and Food Resources to Study the Impacts of Logging and Forest Conversion on Orang-utan Population

Raymond Alfred, Koh Pei Hue, Lee Shan Khee and Rayner Alfred

DOI : 10.3844/ojbsci.2010.73.83

OnLine Journal of Biological Sciences

Volume 10, Issue 2

Pages 73-83


Problem statement: Orang-utan is classified as a totally protected species and is listed as an endangered species in Borneo. The survival of this species is highly dependent on the existence and quality of the lowland forest of Sabah. However, most of the pristine habitats in the lowland area have been converted into other land use activities such as a large scale plantation. This is due to the fact that most of the lowland forests are facing a continuous degradation process that will decrease its commercial value when it comes to generating revenue to the state government. Thus, the efforts to restore the forest are very vital. The main objectives of this study include establishing the relative spatial distribution of orang-utan in order to assess and determine the effects of the forest conversions in four main wild orang-utan population landscape, demonstrating the orang-utan population movement pattern as a response to the heavy logging activities and also quantifying the effect of logging activities on the status of food trees or plant species for orang-utan in their current forest habitat. Approach: In this research, relevant features are constructed in order to study the impacts of logging and forest conversion on Orang-utan population in Borneo. These features include aerial surveys and feeding behaviors. An aerial survey on orang-utan’s nest in four out of six main forest habitats for orang-utan in Sabah has been conducted between May 2005 and June 2009 in order to map the relative distribution and spatial density of the orang-utans. This is conducted in order to determine the impacts of the forest conversion for the last 20 years upon the orang-utan spatial distribution. In this project, three series of aerial surveys, covering Malua Forest Reserve, have been conducted to demonstrate the dynamic movement and habitat utilization by the orang-utan population, due to the logging activities within the forest habitat. A long term observation of the orang-utan feeding behavior in the degraded forest in North Ulu Segama (NUS) has been also conducted to determine their feeding ecology in a logged over forest. Results: This study suggested that (i) forest conversion and logging activities have effects on the orang-utan habitat utilization and movement pattern; (ii) due to the influx of the forest conversion, some of the orang-utan in the forest reserve is concentrated in certain area, adjacent to the boundary of the forest reserve due to their movement limitation by the river network; (iii) the orang-utan population in degraded forest of NUS consumed almost different species of food plants in 2009, compared to year 1974. Conclusion: These results demonstrated that forest conversion and unsustainable logging activities are the main threat for the orang-utans conservation in Sabah. Therefore, the conservation of orang-utan populations are not guaranteed by the establishment of more protected area, but by ensuring that more forest habitats can be managed in sustainable way in order to avoid further forest degradation and to ensure their habitats remain connected to the large forest landscape.


© 2010 Raymond Alfred, Koh Pei Hue, Lee Shan Khee and Rayner Alfred. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.