Orangutans are among the most threatened large mammal species in the world. This is in part because most orangutans live in forests outside protected areas, many of which have been legally degraded or converted. This has led to a rapid reduction of the remaining orangutan habitat forcing animals into increasingly small habitat patches with diminishing food resources. This often leads to conflicts with humans when orangutans are facing food scarcity and feed on available commercial crops such as oil palm and village fruit trees.

2023 Sembilang River
9-4 young palm
9-4 young palm eaten reduced

Natural habitat is destroyed. Young palm with tender leaves, attractive to displaced orangutans, is planted. Orangutans forage on easy to reach nutritional food source, removing leaves and killing or degrading the planted oil palm. Companies and villagers consider them now a liability, not a global asset.

2021 orang

The Problem

A problem facing oil palm plantation concession holders in the immediate area is how to reconcile having legal permits to develop and manage oil palm farms, with the fact that the land also includes a crucial habitat for a significant number of orangutans. In attempting to do so, it is inherent upon the farm owners to recognize their corporate responsibilities with respect to the formal protected status of the orangutan and to establish sustainable operating practices to contribute more fully to the conservation of the orangutans in the area, and better preserve the overall natural biodiversity.

The Solution

The Challenge

Create and Maintain Orangutan Areas in the Wild with Migration Corridors to Keep the Out Of Captivity

Upon completing a preliminary assessment of the current situation at this PT, these recommendations should contribute to the protection and conservation of orangutans bordering and living within the plantation, help reduce the high level of orangutan conflicts that are currently being experienced, and minimize the loss of viable orangutan habitat.

PT-S Plantation

The PT S concession, located in East Kalimantan, is bordered to the north and the south by major production forests. The PT-S concession is 10,040 Ha, of which about 40% (4,040 Ha) has been planted in oil palm to date. The terrain is relatively hilly, making it a challenge to identify suitable land for planting. Consequently, much of the plantation requires terracing.

For the purposes of this report the PT-S is divided into three major areas:
• Southwestern sector – the main farm area + emplacement (infrastructure)
• Northwestern sector – north, not developed
• Northeastern sector – fully planted, separated by community co-op areas


Orangutan Migration Corridor
1 Orang Nest copy 2021

Primary Conflict Areas and Proposed Resolution

Conflict Area A:
Current situation: A deep ravine, which bisects the bottom 2/3s of the Southwestern sector of the farm from north to south, contains a large stretch of relatively intact forested area. The area immediately east of the ravine was cleared and planted over the past year, and a high level of damage by orangutans feeding on the young palm shoots has been reported.
Actions taken: We completed a preliminary survey (multiple transects) of the ravine, which included the level of tree cover, orangutan nest counts, and general biodiversity.
Findings: The ravine comprises approximately 510 Ha. The sides of the ravine, and much of the area within, have steep gradients (30-50%). The level of secondary forest tree cover and general biodiversity is good, and there are an estimated 10-20 resident orangutans, making this a Level 1 High Conservation Value Forest. There was evidence of limited illegal activity in the area, namely small burned areas (presumably for wildlife poaching), and the cutting of trees. The bottom of the ravine exits on the southern PT-S boundary, where the PT-AE was recently granted concession rights to a narrow strip of land between PT-S and the production-forest to the south.
• The ravine should be designated as a conservation set-aside to be called the Rawi Wildlife Corridor and actively protected.
• All further clearing on both sides of the ravine should be put on hold until the exact boundaries can be determined (approximately 2-3 weeks).
• A buffer zone, comprising a road and a 20-30 meter cleared area, should be placed on each side (east and west) of the ravine
• Negotiate with PT-AE to extend the Rawi Wildlife Corridor through their concession Usulan Orangutan Corridor in order to connect to the Production Forest to the south.
• A small PT-S security force, to be trained by the Forestry Department, should be formed to patrol the borders of the ravine for any further illegal human activities, and to stop the orangutans from entering the plantation.
• A more thorough assessment should be completed and a detailed conservation management plan and monitoring program prepared for the area
• The promotion of forest regeneration, and the planting of appropriate fast-growing fruiting trees for the orangutans (enrichment), needs to be included in the conservation management plan.

Conflict Area B
Current situation:
Moderate to severe damage to the new oil palm shoots also have been reported in the Southwestern sector along the Kernyanyan River. Originating in PT-S Northern sector, this river flows down just west of the PT-S Emplacement, and then down through the Southwestern sector just north of the Rawi ravine, before exiting at the southwest corner of the plantation.
Actions taken:
We followed the entire course of the river south through the PT-S concession, making spot checks along the way.
There is continuous good quality riparian forest (50+ meters on each side of the river) down through the area north of the Rawi ravine, except for a few small sections (approx. 50 meters) that could be strengthened (rehabilitated). Occasional orangutan nests were recorded along this stretch of the river, indicating that they are using the riparian forests along the river as a corridor. The tree cover along the rest of the river, after passing north of the ravine, is more sparse and not continuous.
• The conversion of the Rawi ravine into a conservation set-aside with bordering buffer zones should significantly reduce orangutan movement from the ravine, including along the Kernyanyan River.
• The cessation of clearing/planting in this sector of the plantation should also lead to a reduction in orangutan movement and hence conflict areas along the river.
• The land along the river (50 meters minimum on each side) should be made a conservation set-aside (Sentosa Wildlife Corridor- approximately 210 Ha), the precise boundaries for which would be determined after a more thorough survey of the tree cover.
• A conservation management plan should be drafted for the river corridor that includes the promotion of forest regeneration in weaker areas, and the establishment of a vegetation and wildlife-monitoring program.

Conflict Area C
Current situation:
The PT-S Northwestern sector is the only plantation sector yet to be developed. The area was previously a logging concession and there is a large quarry previously used to supply road construction material. The highway is being upgraded by the central government, which, along with the continued development of concessions in the area, should lead to an influx of people into the region, and intrusion into areas not currently occupied or protected. A large Production Forest, which is reportedly in very good condition, forms the northern border of this sector.
Actions taken:
We completed a cursory survey of the Northwestern sector over a 3-day period. This included line transects by foot and driving along forest tracks (old logging roads) while monitoring and making spot checks.
Most of the sector is covered with dense secondary forest growth. The terrain is varied, with some areas quite hilly (>40% incline) while other areas are relatively level (<30%). There is considerable degradation in the more easily accessible areas, primarily from slash-and-burn agriculture for planting mountain rice, bananas, rubber trees, etc., and shelters for storage and guarding the crops, and some more permanent housing. Most of the intrusion appears to be relatively recent (last 1-2 years), and is expanding at an alarming rate, with rampant tree cutting and burning. The areas along the southern, eastern and western concession boundaries are the most affected. The central and northern reaches of the sector are less accessible, and thus more pristine, except along old logging roads where slash and burn is taking place. There is evidence of orangutans (estimated 20-30 individuals) throughout the sector, in a patchy distribution. The area along the Kernyanyan River was particularly notable, with good tree succession for the most part, and large numbers of orangutans, but even this area is being encroached upon via logging roads, with significant slash-and-burn activities. It is our strong conviction that, unless the Company presents a significant presence on the ground, and immediately initiates discussions with the local community representatives, the encroachment will continue and much of the remaining forested areas, and the resident orangutan population will be lost.
• Negotiate with the local communities to secure the land within the Northwestern sector that has been encroached upon.
• Prepare a conservation management plan for the Northwestern sector, which will include a major conservation set-aside (PT-S Conservation Area – approximately 1210 Ha) to provide permanent protected habitat for the resident orangutans.
• Prepare the surrounding flatter areas (approximately 2270 Ha) for compatible development, including planting oil palm, to provide a buffer area which should help prevent future incursion by people living outside the concession.
• Pursue the possibility of completing an aerial survey of the sector, using a remotely controlled ultra-light plane (cost approximately US $1.50/Ha) to assist in preparing the conservation management plan, and to document baseline vegetation cover and cleared areas.
• Begin developing a community relations/education program


Implementation of the above recommendations will serve several purposes. First, it will help conserve the remaining orangutan habitat within and around the PT-S farm and place the Company in a leadership role in promoting orangutan conservation at the landscape level. It will also become the basis for a working model for establishing sustainable operating practices for oil palm plantations located in areas harboring orangutans that include a strong orangutan conservation component and a community relations program. Finally, the proposed strategic planting of oil palm in the Northwestern sector is an innovative approach that should help ensure the conservation of the resident orangutans and the long-term protection of their habitat.