Reintroduction is defined as an attempt to establish a species (or subspecies) in an area which was once part of its historical range, but from which it has subsequently disappeared.  The term ‘reintroduction’ is preferred to ‘release’, as it infers that the species formerly inhabited the particular type of environment into which they are being released after rehabilitation.

It is believed that the reintroduction of a species to the wild is unlikely to be successful without prior rehabilitation, which is defined as the conditioning of captive animals to behave in a more natural manner so that they will have a greater chance of successful adjustment to the wild.

Our work to rehabilitate the gibbons involves three different stages. These are a quarantine stage, a rehabilitation stage and a reintroduction stage. Each of these stages is explained below.


When gibbons first arrive, they are given a full medical examination, deworming, tuberculosis test and blood test. Blood samples are taken to check for diseases such as Herpes simplex virus, Hepatitis A, Hepatitis B, and HIV. If a gibbon tests positive for any diseases or has any serious body deformations, they will not be able to be released. These will remain in Quarantine and may be rehomed to Wild Animal Rescue and Education Centre (WARED), our sister project in Ban Talae Nork, Ranong at a later date.

At Wild Animal Rescue and Education Centre, Ban Talae Nork, in Ranong province, they look after a variety of animals. WARF is currrently developing this site as a sanctuary for rescued wild animals. Here land is more affordable, so the animals have large cages in amongst the trees. Artificial islands have been constructed here to house gibbons that have diseases. These islands mean that the gibbons can be free in the trees but can still be monitored and are not in contact with the wild population.


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Even if they are free from diseases new gibbons will stay in Quarantine for at least 3 months. For most gibbons, this is the first time they encounter other gibbons. We place them individually into large enclosures where they can begin to learn to act more naturally by observing the other gibbons. There is a no contact policy for staff and volunteers working in the area to encourage the gibbon to seek attention from other gibbons and not from humans. A health and behavioral check is performed everyday. If they are healthy and are beginning to act more naturally, they are transferred to the Rehabilitation site where they undergo an extensive rehabilitation programme.


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Before the gibbons are ready for reintroduction they are put through a long rehabilitation programme. This involves a series of environments which encourage their natural behaviours and provide them with the opportunity to practice brachiating and eating natural foods, and ensures maximum contact with other gibbons and minimum contact with humans. Juvenile gibbons are housed together, and adults are given the chance to form pairs. Here, after a long acclimatisation period, the gibbons will learn to survive by themselves. Continuous research is carried out to assess the gibbons’ development at each stage. Not all of the gibbons at the GRP meet the criteria for the rehabilitation programme and some do not make it to the release stage. With these gibbons, we provide the best care we can.


After 23 years of research and more than 70 gibbons released (both on uninhabited islands and in Khao Phra Theaw non-hunting area), with varying outcomes, we have found the following to be the most successful re-introduction method.


We currently have seven groups, 21 gibbons (5 wild born survive, June 2015) in the Khao Phra Thaew non-hunting area that have been released using soft release method. 6 of these families are no longer rely on us for food.

The gibbons that the GRP receives have been taken from the wild at a very young age and held in captivity, they therefore lack the necessary skills for them to survive in the wild on their own. At the GRP, the gibbons are kept on a diet similar to that which they would receive in the rainforest and are placed through a series of habitats that encourage their natural behaviour.

Human contact is kept to a minimum to promote social behaviour within their species. The gibbons are also paired with a mate to encourage the formation of families; previous research illustrates an increased success rate for a reintroduction if it occurs with the same social structure as would be found in the wild. Observations are conducted throughout the rehabilitation process.

If the gibbon family is exhibiting characteristics similar to that of data collected from wild gibbon populations they are then transferred to the training cage within the Khao Phra Thaew non-hunting area, in the care of the National Park, Wildlife and Plant Conservation Department. They will spend at least three months in this cage, after which they are transferred to the acclimatisation cage.

Acclimatisation Cage

Acclimatisation Cage


The acclimatisation cage is situated within a system of trails arranged in a grid to track their location after release. It is positioned at least 20 m above the rainforest floor to acclimate the family to the upper canopy where they naturally occur in the wild. They are monitored here for at least ten days; if the family is exhibiting natural behaviour, the cage door will be opened and the gibbons are allowed to move freely. This strategy for reintroduction is called soft release. During the first few weeks the family is reluctant to venture far from the release cage and cannot find enough available food sources to survive, and so it is necessary for us to provide supplementary feeding. Since they are generally capable of foraging for leafy food, the gibbons are fed only fruits that can be found within the forest. The feeding stations are moved farther away from the acclimatisation cage and deeper into the forest to encourage the natural expansion of their territory. Gradually the amount of food and human contact is decreased as the family becomes more capable of foraging for food on their own and exhibiting characteristics analogous to wild gibbon populations.

Follow up and Observation

Follow up study after release: Behavioural observations are recorded every day after the release to ensure the success of the reintroduction. At least two individuals are required to perform an adequate data collection. A Focal Gibbon Observation Sheet records the location within the grid system, behaviour, social behaviour of the focal gibbon, relation to other gibbons, eating habits, and food intake. This is filled in every 2 minutes, and provides statistical data which can be elaborated to provide information on their daily activities. A second Social Observation Sheet is used which monitors their social behaviour and singing patterns.


Follow up and Observation



The data is analyzed and compared to that of the data previously collected from the group while in rehabilitation, to that of other gibbons in the process elsewhere, and to that of wild populations. From this data a better understanding of their behaviour and a more successful method of rehabilitation and reintroduction is hoped to be gained.


Reintroducing ex-captive gibbons back to the wild is not the preferred method of gibbon preservation. It is time consuming, expensive and not always successful. In order to help save the gibbons, we must use both conservation and education. We need to educate local people and tourists about the importance of conserving these animals and their habitat, as well as not supporting any businesses who profit from exploiting wild animals.

The Centre for Conservation, Education and Fundraising performs two very important functions: public education, and the basis of financial support for the project. The centre is located near the entrance of the Khao Phra Thaew non-hunting area, near a waterfall visited by both tourists and local people. Visitors to the centre are able to view (from a distance) gibbons in some of our holding cages. Between the hours of 9am and 4.30pm every visitor to the centre is greeted by a staff member or volunteer and provided with both verbal and written information. This information is provided in over 10 languages and includes:

          – The fact that the white-handed gibbon is an endangered species.

          – The major factors influencing the wild gibbon populations.

          – How tourists can help to alleviate pressure from poaching by not patronising establishments with pet wild animals or paying for photographs with animals.

           – By purchasing gibbon related merchandise, adopting a gibbon or giving a donation they are helping us to carry on our efforts to rehabilitate these animals and conserve their natural environment.

           – What action should be taken if they see a wild animal being held in captivity.

As well as tourists, we regularly host school groups from throughout Thailand and are able to provide information that we hope will give the next generation of local people a better understanding of the natural environment.

Another important aspect of our education work is to educate local people about wildlife and the importance of conservation. One way in which we do this is to visit local schools. Before and after releasing gibbons we visit the schools surrounding Khao Phra Thaew park. We also visit schools, colleges and universities across Phuket. We hope that the children will spread the message to their families, and that in the future they won’t hunt or exploit these animals.



Information distribution In order to reach tourists that do not visit our centre, we distribute leaflets to the major hotels, tourist information centres and beaches. These are the areas where gibbons are most commonly used by people or businesses for economic gain and so our leaflets specifically highlight this problem.

We also produce educational leaflets which we can distribute to local villages and community groups. We concentrate on the villages surrounding the forest because we know that members of these communities still go into the forest to hunt. We hope that by educating these people we will ensure the continued safety of the gibbons we are releasing.


Community Relations 

The project tries to keep good relations with local people so that we can continue to do our work and so we can call on them for help if we need it. We therefore carry out a number of tasks to develop good community relations. We regularly have groups of veterinary students staying at the project who help out with this work. When they are here we invite local people to bring in their dogs and cats to be sterilized. We offer this service free of charge, so it helps the local people save money as well as ensure they will not have unwanted young cats and dogs in the future.




We are planning to start organising ecotours for visitors to Phuket. These tours would involve the study of various ecosystems, including the rainforest in Khao Phra Thaew national park, as well as bird-watching in the mangroves and fishing in Phang Nga Bay. We would like to organise these tours with the help of local people, so that tourists will stay with families in the village and join them on fishing trips etc. Organising the tours in this way would mean that local people could earn extra money. They usually rely on hunting and collecting food stuffs from the forest to supplement their incomes, so our hope is that the ecotours would mean that they no longer need to do this. It should also provide a good opportunity for tourists to experience some real Thai culture and learn about the Thai way of life.



In recent years Thailand has seen massive developments in terms of housing, hotels and clearing of land for shrimp farms, fruit trees, rubber plantations etc. This has taken a heavy toll on Thailand’s wildlife. Logging, poaching and loss of habitat have caused a dramatic increase in the number of wild animals at risk.

The Gibbon Rehabilitation Project and the Wild Animal Rescue Foundation of Thailand (WARF) are amongst the few organizations in Thailand offering a service to rescue and provide medical treatment for wild animals. Our work involves extensive travel, since we are often called on to respond to emergencies that take place in remote areas of the country. The Mobile Animal Clinic (MAC) helps us to attain our goal to rescue wild animals in distress throughout Thailand. The vehicle gives the veterinarians the possibility to perform rescue operations more effectively and to return the animals to the wild once they are well.



The launch of WARF’s Mobile Animal Clinic (MAC) was on the 2nd of October 2002. The 4 wheel drive vehicle, was kindly donated by the Royal Society for the Protection of Animals (RSPCA) International Division. The RSPCA is an international organisation whose primary objective is animal welfare. They kindly donated this new vehicle to WARF for use as a mobile clinic at the Gibbon Rehabilitation Project (GRP), Phuket and it’s new wildlife and education centre at Baan Talae Nork, Ranong. The all-terrain vehicle is equipped with an air-conditioned animal-carrying compartment and is for the use of our full time Thai veterinary surgeon, Dr Tum.

EDUCATION: The MAC truck is also used for our education programme. The GRP holds talks for people, schools and colleges, and arranges tours and workshops to try to help people understand and protect the gibbons and their forest. This involves us transporting staff and volunteers to the schools and villages. We employ ‘gibbon guardians’: local people that live and work in and around the forest. They act as community educators, become involved in protecting the gibbons from poaching and assist in the post-reintroduction follow-up studies.