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Gibbon Rehabilitation Project (GRP) : Phuket
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Project Overview:

The Gibbon Rehabilitation Project (GRP) is a research division of The Wild Animal Rescue Foundation of Thailand. Khun Noppadol Preuksawan, the chief of the Royal Forestry Department in Phuket together with the Asian Wildlife Fund and support from WARF, established it in 1992. Terrance Dillon Morin was also a driving force.

In 1994 GRP became a research division of WARF. The project's goal is to save gibbons and their rainforest habitat through rehabilitation and education. Find out more about how to become a volunteer for this project. Also visit the new project website at www.gibbonproject.org


Project Location:

The Rehabilitation site is in Khao Pra Theaw Non-Hunting Area at the Bang Pae Waterfall, Phuket, Thailand. It is about 9 km. east from the Heroines Monument. You can visit our center and see some of the gibbons from the viewing platform. The Center open daily 9am to 4pm. We do not charge an entrance fee. If you'd life t visit in a big group, please contact our office. We are around 20 km away from Phuket International Airport, from here you should follow the sign to the Heroines monument and turn left onto road 4027. Follow the road until you see the sign for Bang Pae Waterfall, where you turn left and drive for 1 km to the entrance of the park. You will have to pay an entrance fee to the National Park Wldlife and Plant Conservation Department. Once inside the park a car par is provided and you can walk from here to our center.

Project Objectives:

  1. Develop a method to successfully rehabilitate white-handed gibbons back into their natural habitat. The GRP has been testing methods of reintroduction for the past 10 years. Every reintroduction is a learning opportunity. Reintroductions remain a relatively new division of conservation movement as well as uncharted terrain for research.
  2. End the demand for the illegal use of gibbons as toursits attractions and as pets: Throgh the education of visitors at our Center for Conservation Education and Fund-Raising, the GRP hopes to create awareness of the plight f the captive gibbon and to the role that tourism plays in the demand for baby gibbons.
  3. To repopulate the last remaining rainforest in Phuket-Khao Pra Theaw Non-Hunting Area (National Park, Wildlife and Plant Conservation Department). The gibbons were poached to extinction in Phuket over 25 years ago. The GRP hopes to repopulat this forest thought the rehabilitation for gibbons that were previously being help in captivity. The GRP has successfully reintroduced group in October of 2002, a second family in August 2003, a third group was reintroduced at the end of 2004 and many more in the near future.
  4. To create awareness of the importance of conservation of the environment: The GRP is also a effective resource for teaching the local community about the importance of conservation. The GRP runds education programs to enable local villagers and children to see the forest and its animalsas an essential life supporting source.
  5. Provide the opportunity for volunteers to study the white-handed gibbon: volnteers come from all over the world to study the white-handed gibbon. The gibbons at the GRP allow for the many forms of research, such as reintroduction methods, behavioural research of both captive and released gibbons, and research into deseases of gibbons in captivity.

By means of our education programme we aim to reduce poaching and deforestation both gaining support for our project and assisting the conservation movement in Thailand. The GRP is an effective resource for teaching the local community and foreign tourists. It attracts international students and volunteers who wish to study gibbons. Gibbon conservation is not a problem unique to Thailand. What we learn here will be passed on to other projects with similar aims.

Project tasks:

Gibbons are small, monogamous, territorial apes that live in the upper canopy of the lowland rainforest of South East Asia. These apes have a unique form of locomotion, an arm-to-arm swinging movement called brachiation. Also unique to gibbons are their loud territorial songs, which can be heard for several kilometers in the rainforest. In the wild, gibbons feed mainly fruits, leaves, flowers and insects. They can live for more than 30 years.

Thailand's gibbons are threatened mainly by destruction of their rainforest habitat, but they are also poached for meat, medicine and the lucrative pet trade. All nine species in SE Asia are listed in Appendix 1 of the Convention in International Trade in Endangered Species (CITES). In Thailand it has been illegal to take gibbons from the wild since 1992. Sadly, this practice still continues.

The GRP works with White-Handed gibbons (Hylobates lar); the most widespread of the four species found in Thailand. Gibbon babies are acquired when their mothers are shot; they are then illegally sold as pets or as tourist attractions. Sometimes they end up in bars, being taunted by tourists, forced to drink whisky and smoke cigarettes. This solitary existence is a far cry from the family life they would normally have in the wild. When gibbons reach sexual maturity, at 6-7 years, they can become aggressive and so they often get dumped or killed. If they are kept, their canines are filed down or removed and are often housed in small cages or chained up. As a result of illegal poaching, much of the rainforest in Thailand is under-populated with gibbons. At the GRP we work to rehabilitate the gibbons, which have come from captivity. Our objective is to repopulate the rainforests where gibbons once lived before they were poached to near extinction.

When a gibbon comes to the GRP it receives a medical check, undergoes blood tests for various diseases and is then placed in a quarantine area. Before gibbons are ready for release they are put through a long rehabilitation programme . This involves putting them through a series of environments, which encourages their natural behaviours and provides them with the opportunity to practice brachiating, eating natural foods and having minimum contact with humans. Juvenile gibbons are put together and adults have the opportunity to form pairs.

The GRP is currently funded by donations from the public who visit our waterfall site, from our adoption and volunteer programmes and from philanthropic companies. The volunteers make a donation to the GRP as well as giving their time and energy, many stay for several months at a time, improving their studies and using their qualifications to help the project. We constantly need funds to keep the project alive.

Ideally reintroduction projects should be able to accept all of the Guidelines for Reintroduction, IUCN/SSC Reintroduction Specialist Group, any International Guidelines or International Reintroduction Standards. 

In reality though, each organization is different and situations, resources, and limitations vary. For this reason we need to work together and accept that those organizations with less resources are doing what they can.

We currently have 9 gibbons in the reintroduction site that have been released using soft release method (gibbon held in enclosures at the reintroduction site prior to release, to assist them in adjusting to their new environment). Release stock types are captive and captive-born gibbons.

It is estimated that once we have chosen a family group, it takes approximately 1 year to complete the release. With this in mind our goal is to release at least one gibbon group every year. Khao Phra Theaw non-hunting area can support at least 60 groups of gibbons, so we can carry on this work for many years to come. It also allows area for the reintroduced gibbons to breed and create a wild population.

How Rehabilitaion Works...

Rehabilitation involves putting healthy captive gibbons into a series of environments which promote the physical health and natural behaviour that is necessary for survival in the wild. This is done in three phases, starting with in-cage rehabilitation and leading to the final acclimatization period in conjunction with release in the rainforest. To be successful, not only must the gibbon behave naturally, it is also crucial that the reintroduction habitat be suitable and protected from poaching, encroachment and logging. If humans are living in the area, a consultation and education process is vital. Planning is from the ground up and involves the employment of local people who act as educators and 'gibbon guardians'.



New gibbons must undergo veterinary clearance and a quarantine period to make sure they are disease-free. This requires a thorough veterinary check and medical tests for TB, Herpes Simplex and Hepatitis A, B. All new gibbons are kept in quarantine for a period of 90 days.


The gibbons are kept in large enclosures at Bang Pae Waterfall. They are fed twice each day and observed regularly. We encourage their natural behaviours: for example, the opportunity to practice brachiating, eat natural foods, have maximum contact with other gibbons and minimum contact with humans. Adult gibbons will be placed in pairs whilst the younger gibbons will be put in small groups with gibbons of a similar age. The gibbons are observed each day for the first few months they are here. It is important to observe whether gibbons that have been alone as pets can get along with other gibbons in the way that wild gibbons would and whether they display the appropriate behaviours.

Their diet must be altered to one rich in fresh fruits and vitamins. We introduce them to a wide variety of healthy food including wild food straight from the forest.

FITNESS: The gibbons are put into large cages with ropes and branches where they can brachiate. Here they develop strong muscles and good motor skills.

SOCIALIZATION: The captive must learn to behave like wild gibbons again. To get the gibbons to socialize with their own kind and avoid humans, they are handled as little as possible. In this way they can learn to swing, sing and groom in peace.
PAIRING: When a sexually mature gibbon is selected they are put into a cage with another suitable gibbon of the opposite sex. This is to encourage the bonding of a pair. Sometimes it can take a long time to find the right partner. The pairing is done in order to help them survive when they are finally released into the wild; a strong bond makes it easier for them to adapt and establish a new territory. When they do bond, some give birth in captivity. These bonded pairs are put in a minimum contact area in large cages. Six pairs have now bred in captivity.



A: TRAINING: A training cage has been built in Khao Pha Theaw Royal non-hunting area. The cage is situated about half an hour walk from the Rehabilitation site. This cage is used for a family of gibbons to explore and adapt to the rainforest environment before moving them to the Acclimatisation cage. They will spend up to 3 months in this cage. A special feeding system is used to ensure that the gibbons have no contact with humans. Feeding is also from the top of the cage. This is a benefit as gibbons naturally spend most of their lives in the upper canopy of the forest.

B: RELEASE: The final release for the gibbons is in Khao Pha Theaw Non-Hunting area. The minimum area for a genetically viable population is considered to be 10 square kilometers. Gibbons used to live here twenty five years ago, before they were poached to extinction. After the period of time in the training cage, the family will be moved to an Release cage which is suspended 20 meters above the forest floor. The door will not be opened for 10 days, so they can adapt to the surroundings. The door is then opened and the gibbons are allowed to leave in their own time. They will generally stay around the release cage for the first few days, going in and out. After 5 days the door will be closed and the gibbons will move further away from the cage, finding their own territory.

C: FOLLOW-UP: During the first few days after the release, gibbons are still insecure and spend much of their time nearby the cage. They are still being fed fruits in the morning and afternoon to ensure that they receive enough food. To encourage them to start exploring further away from the release cage, we move the feeding baskets deeper and deeper into the forest. After a long acclimation period, they will eventually expand their territory naturally and be able to survive on their own. Regular observations will be maintained by staff and help from volunteers in order to ascertain the success of the release.

GRP Conservation Education Centre: We also have a Centre for Conservation, Education and Fundraising.The Centre 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 Royal Thai Non-Hunting Area, near a waterfall used by both tourists and local people. Visitors to the centre are able to view (from a distance) gibbons in someof our holding cages. Between the hours of 9am and 4pm 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.


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.

Released Gibbons

After 10 years of releasing gibbons, with varying outcomes, we have developed the rehabilitation programme in place now. This programme has proved successful and we now have 10 gibbons living in the forest.


It is estimated that once we have chosen a family group, it takes approximately 1 year to complete the release. With this in mind our goal is to release at least one gibbon group every year. Khao Phra Theaw non-hunting area can support at least 60 groups of gibbons, so we can carry on this work for many years to come. It also allows area for the reintroduced gibbons to breed and create a wild population. After we have released a group of gibbons it is necessary to provide them with a small amount of supplementary food, which is gradually reduced until it is no longer needed.

First group

We released the first group of gibbons (Adult male=Joe, Adult female=Kip and Juvenile male offspring=Thong) on the 27th of September 2002, and the female, Kip, gave birth to a female baby, who we named Hope on the 21st October 2002.


In October 2006, Kip gave birth to another baby who we named "Toffee". We can give an educated estimate of the date of birth as the 21st October 2006.


Aggression towards humans was showed by the two adults immediately after they left the cage. The male approached people jumping from tree to tree at a low height or running bipedally on the ground. Some observers, including both volunteers and staff were scratched or bitten by the animal. The female (and the juvenile) eliminated sometimes on humans or things belonging to them; she also scratched some observers and seemed to dislike particularly female observers, while she didn't pay attention to male observers. If a gibbon begins to show aggresive behavior, the staff in the forest use sling shots to scare the animal off. Because of past experience the gibbons know to stay away from the sling shots, even if their is nothing in them. The aggressiveness of the adult male towards observers seemed to decrease during the study period, while the adult female still showed aggressive behavior to every new female observer that she didn't like, hooting rapidly and trying to scratch. Apart from this type of interaction the gibbons (adults) were not interested in observers' activity and objects, with the exception of food, which they didn't hesitate to take if left unwatched. Food manipulation (both for humans and for feeding stations) by observers was also a reason for aggressive interactions. Interactions with humans were performed by the two adults but not by the juvenile. The juvenile limited its interactions in watching people, while the adults showed physical contact, attacking observers several times. Thus, the rate of aggressiveness decreased through the study period.


Second group

The second group (Adult Male=Bo, Adult female=Lek, Juvenile female offspring=Dao and Male offspring= Arun) were released on 15th of August 2003. This group appears easier to observe than the first group and are much friendlier towards humans. Up till 4 months after the release, the aggressiveness of two adults towards observers seemed to increase and they attacked the observers during feeding time.
The adult male liked to come close to humans more than the other group members, but sometimes he showed signs of aggressiveness, yawning (showing his canines) towards an observer. Usually when he came close to observers, we would shout or simply walk away. Observers used to shoot him with the sling shots, but he was less scared of it than the gibbons of the first group released. Sometimes we did not see him and he came close to us quickly. In this kind of situation we don't want to shout (we believe it may make him excited and he would bite us). Then he would embrace us. Unfortunatly this was a bad sign. Bo began to return to the rehab site, leaving his female mate and offspring. After reintroducing him on six different occasions, he had to be sterilized, and will now stay in an enclosure for the rest of his life.
For supplemental feeding, usually one Thai staff member goes to work alone in the forest. On the 12th of March 2004, Dr. Tum went to feed, and the Adult male jumped (showing his canines in an aggressive manner) to bite him 2 times, but the second time Dr. Tum hit the adult male with a wooden stick. After that exchange, the aggressive behavior of the adult male seemed to decrease.
Unfortunately, the adult male repeatedly returned to the rehabilitation site. After several attempts to reintroduce him back to his family in the forest we decided that he would remain at the rehabilitation site for the foreseeable future.


Third Group

We released a third group of gibbons (Adult Male=Bird, Adult Female=Pompam, Juvenile female offspring=Sabai, Male offspring=Yoge)  on the 10th December 2004, in the beginning this group was doing well in the forest.  The family tended to stay together and move around the forest looking for food trees.   Bird, the adult male, showed signs of aggressive behavior.  He attacked one of our volunteers and came very close to at least two others.  He was afraid of the Thai staff and tended only to be interested in attacking females.  We started to take sling shots into the forest and have kidney beans as ammunition, but often just the sight of the sling shot was enough to send Bird away.  The rest of the family has little to no interest in us aside from feeding time.
On the 18th of December 2004 Bird went missing, and although he was seen again on the 21st December, on the 21st February 2005 he disappeared again and has not been seen since.
After Bird went missing, the rest of the family seemed to be doing well, until the mother, Pompam also went missing on the 1st December 2005. We believe Pompam is dead and were concerned for the safety of the two offspring, Yoge and Sabai.

On the 7th February 2006 we released two juvenile males, Khan Ngean and Bank, who had been living at a resort in Khao Lak. Sabai and Yoge were seen playing with these two while they were still in the acclimitisation cage and it was hoped they would stay together. Sadly Khan Ngean became ill soon after the release and had to be bought back to the clinic for treatment, however he died several days later due to intestinal complications.

On the 17th of February we were unable to find Sabai and she was missing for a month. On the 18th March we found her in a different part of the forest. Staff brought her back to the acclimitisation cage in Arun territory. However during the night, the females from Arun group, Lek and Dao fought with Sabai through the Cage and left her with serious wounds on her arms and hands. We had to bring Sabai back to the clinic for veterinary treatment. As the other females had rejected her, we made the decision to keep Sabai at our Rehabilitation site rather than leaving her in the forest alone. When she is older and we have found her a mate she will be released again. We suspected that Yoge and Bank had joined Arun group after staff observed them playing with Dao on the 11th of February. We later confirmed this and now call the second group, Arun Group. They are now off of our food supply and can find food enough for themselves.


Fourth Group

On the 10th March 2006 we released a fourth group of gibbons (Adult Male=Bozo, Adult Female=Kushta, Infant Male offspring=Nat) unfortunately this release was unsuccessfull as Bozo went missing just two days after the initial release and despite our best efforts was not found in the following month. It was decided to bring Kushta and Nat back to our rehabilitation site on the 12th of April 2006. When Nat is older we hope that Kushta may be paired with another male and have a second chance to be released.


Working in Forest:
Releasing the gibbons into the forest requires a large amount of work both before and after the release. We follow a soft release strategy where we provide the gibbons with fruit after they have been released. A member of staff therefore has to go into the forest to feed the released gibbons. The first family is now getting food every 2 days, but the recently released gibbons get the food everyday. The feeding also allows us to check the gibbons everyday, so we know that they are safe and healthy.

We also collect data for our research into rehabilitated gibbons. Groups of staff and volunteers will spend several days a week in the forest following and observing the gibbons. These observations start at around 6 in the morning when the gibbons will just be waking up and continue throughout the day. We follow them for the whole day and do not leave until they are sleeping. Data is recorded every 10 minutes throughout the day to record the positions of the gibbons in the forest and in relation to each other. We also record any social behaviours. At the same time we will observe a focal gibbon. Data on this gibbon will be recorded every 2 minutes.

MAPPING: An important aspect of our work is mapping because the area in Khao Pha Theaw royal non-hunting area that we use for the releases has not been accurately mapped. We have set up a grid system within the forest so that we can accurately record where the gibbons are. These grid systems need to be recorded on maps. With the maps we can also record the territories of the gibbon families we are releasing. It is important for us to know the territories so that we can make sure future releases are not within them. Before we can release a new family we have find them a suitable territory, we than have to cut trails and map the new area.

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