Related Topics  Food Species that are consumed by our released gibbons Gibbon Behaviours Ecological Community in Reintroduction Site Download GRP Report and Articles

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 fewer resources are doing the best that they can.

There are now 21 gibbons at the reintroduction site in Khao Phra Thaew Non-hunting Area, 14 are fully independent and 7 (two families) are receiving supplementary food. The Tony group (Jita, Tony and Claire) were released on December 10th 2009, Jita (female) went missing and no record since the 29th March 2011. And the Kushta group (Kushta, Peemai, Nat and Muki) were released in April/May 2011. First, Kushta and Peemai were released on April 27th. The reason for this is that Arun had been at the training cage while the Kushta family was inside, and it was thought that Arun was looking for a mate. When Kushta and Peemai were released Arun showed interest in Kushta and was also very protective towards Peemai so it is very likely that Arun will become part of this family. Nat and Muki were released on May 2nd and all of the gibbons have taken to each other as well as their new environment. On the 16th July 2011 Peemai went missing and found again on the 16th September 2011.

Since the first released family, 8 babies have been born in the forest.

All have been released using the Soft Release Method (gibbons are 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 an adequate area for the reintroduced gibbons to breed and create a wild population.

Stopping the Supplemental feeding

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. For example since the 19th April 2004, we decided that "Kip group" had been in the wild for a sufficient time (since October 2002) to learn how to forage alone. The small amount of food we were providing them with was increasingly being ignored in favor of food they found themselves, particularly once the rainy season began and more food was naturally available. We stopped feeding them, but continue with regular observations. If all goes well, we will consider them fully rehabilitated and focus our efforts on releasing a new family.

We stopped feeding the Lek Group on 24th July 2005 and stopped feeding the Payu group on the 7th June 2009. But now we still feeding the Tony's group 0.5 kg of fruit every 2 days and the Kushta group 4 kg of fruit every day.

Feeding Basket for Released Gibbons (Left). Released Gibbons feeding from tree tops (Right)

Follow-up and Data Collection

Radio telemetry is recommended by some researchers. This method proved to be successful for monitoring released primates, like in the case of the golden lion tamarins released in a reserve in Brazil. Unfortunately, due to its high cost, this technique is unable to be used at GRP.

We are able to use only follow-up observations to evaluate the success of the release. The study groups were watched every day during the first month and after that several days each month, the amount varying depending on the number of observers available. Follow-up studies may be required for many years after the release. Observations include general behavior, grooming behaviors, duetting, general appearance and vigor, monitoring of range, height reached in the canopy, distances between group members, identification of types of natural food eaten.

The free animals were also discouraged from following and interacting with humans.
To prevent attacks on the observers, the adults were kept at a distance of at least 5 meters using a sling shot which sometimes contained harmless beans and other times contained nothing at all (just the noise of it scared them off)..

Human Aggression One of the gibbons (Tony) attacked a member of staff causing superficial injury. So for safety reasons only staff members and not volunteers take food to his group. Gibbons are very protective of their families and this is what Tony was doing. Aggression towards humans included the following behaviors: jaw-snapping, loud vocalization, vigorous locomotion, legs and arms spread (to show a large surface and consequently to increase the body size), touching, grabbing, and biting.

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Observation and data collection (1), (2), (3), (4), (5), (6)

Current Released GIbbons in Khao Phra Thaew Non-hunting Area

First group .... "Kip Group"

We released the first group of gibbons (Joe; adult male, Kip; adult female and Thong; sub adult male offspring, born at Rehabilitation Site) on the 5th October 2002, and the female, Kip, gave birth to a female baby, who we named "Hope" on the 21st October 2002. On the 26th October 2006, during observation, our staff and volunteers found that Kip had given birth to her third female baby, who we named "Toffee". We can give an educated estimate of the date of birth as the 21st of October. On the 30th of December 2009 our staff discovered Kip had given birth again to a male who we named “Omyim”

This group has continued to be observed in the forest on a regular basis. Supplementary feeding of this group ceased early (the 19th April 2004) as they now forage and function as a wild family of gibbons. Tourists can see or hear them when they are singing by walking up along the nature trail.

..... Group members:

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Kip group members..... Joe; father (1), Kip and Omyim; mother and male offspring (2), Hope; female offspring(3),

Thong; adult male offspring(4), Toffee; female offspring (5), Omyim and Kip (6), Omyim (7)

Hope is now almost 9 years old, and is thriving through her adolescence. She has been seen on several occasions spending time with Yoge. They seem to have paired and may have a baby very soon. Toffee is 4 years old and is displaying increasing independence from her mother but is still under her watchful eye. Thong, the eldest child, almost 10 years old has now reached sexual maturity and had been observed spending more and more time away from the family unit to be with Dao (9 years old female of Lek group), they were seen playing and copulating for 5 months before they split up and Dao left to join with the newly released Payu group. Now Thong is spending more time back with his own family though also spending time alone.

However, this situation is very promising and is demonstrating that newly wild ex-captive gibbons released by the GRP are capable of forming monogamous relationships just as their wild-born counterparts do. It also illustrates that further releases should provide sufficient variation in order to make a long-term wild population viable.

Dao and Thong copulating on the top of the tree ... !!!!

Second group .... "Lek Group"

The second group (Bo; adult male, Lek; adult female, Dao; juvenile female offspring and Arun; Male offspring, both born at the Rehabilitation Site) was released on the 15th August 2003.

This group appeared easier to observe than the first group and was much friendlier towards humans. The adult male, Bo, particularly liked to approach observers. Observers used to shoot at him with a sling shot, but he was not afraid of it. Sometimes we would not see him creep up on us and were wary of shouting at him in this kind of situation (in case it would excite him and he’d attack). Then he would embrace us. In March 2004 Bo showed aggressive behavior to an observer at feeding time and the observer had to beat him off with a stick. After that exchange, Bo’s aggressive behavior seemed to decrease. Unfortunately, Bo 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. This left Lek alone with the two offspring, but under observation all three seemed to be doing very well in the wild on their own.

Group Members...

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Lek group members.....Bo; father (1), Lek; mother (2), Dao; sub adult female (3), Arun; juvenile male (4)

After some time, the three were joined by two other gibbons that belonged to a subsequent release that had failed (Yoge group), Yoge and Sabai. Yoge and Sabai are the offspring of Bird (male) and Pompam (female) who were released on the 10th December 2004 (the third group to be released). In the beginning this group was doing well in the forest; the family tended to stay together and move around the forest looking for trees bearing food. Bird, the adult male, showed signs of aggressive behaviour. 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 decided to use a sling shot like with Bo and his behavior seemed to improve. 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 of December 2005. We concluded that Pompam must be dead and much to our dismay our worries were confirmed when we discovered her skull and some other bones and fur in the forest lying next to some gun cartridges on the 17th of March 2006. She had been poached. We were obviously concerned for the safety of the two offspring, Yoge and Sabai, but allowed them to remain in the forest for the time being under observation.

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 Acclimatization 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. We suspected that Yoge and Bank had joined with the Lek group after staff observed them playing with Dao on the 11th February 2006. We can happily confirm that Bank has formed a breeding pair with Lek and on the 20th November 2007 we discovered that she had given birth to a baby. Unfortunately, though, the baby did not survive, as we discovered four days later that Lek was no longer carrying the infant, and concluded that it had died of three possible causes: either it had been taken by a predator, such as a python or a bird, had been dropped by Lek-which is possible as her previous offspring were born in cages, where they would not be harmed if dropped-or that the baby was simply too weak to survive.

                                                                                   New Members of Lek Group....

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Bank; adult male(1),    Yoge; Juvenile male from the third group (2)

On the 17th of February 2006 we were unable to find Sabai. She was finally traced on the 18th March in a different part of the forest. Staff brought her back to the acclimatization cage in Lek territory. However during the night, the females from the Lek 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 leave her in the forest alone. Attempts were made, unsuccessfully, to pair Sabai with a mate. Shortly after her return to the Rehabilitation Site, Sabai tragically died of Pneumonia.

On the 25th of September 2008, Lek (with Bank the father) gave birth to her second male baby, who we named "Redy". He is the fourth gibbon born in Khao Phra Theaw Non-hunting Area since we began releasing the gibbons back to this forest (2002). He is 2 years old and now went missing has not been seen since September 19th 2010.

Lek and Peanut (New born, Above right), Lek and Redy (Redy who went missing, Above left)...

NEW BORN! On the 30th June 2011, during an observation with the ISV group (International student volunteers), we could have the pleasure to see a new baby born (the third born of Lek and Bank) named Peanut. We don’t know how old is it, approximately one month, and also we still not sure about the gender.

"Arun" has recently been with Kushta family which were released in April/May 2011..

Third group (Fifth Released) .... "Payu Group"

This group (Khao; adult male, Nuan; adult female, Payu; juvenile male offspring and Namthip; infant female, both born at the Rehabilitation Site) were first released on the 7th of June 2007 in commemoration of the King of Thailand who celebrated his 80th birthday in the same year. However it soon became apparent that the Lek group were clashing over territory with the Payu group, as they fought shortly after we opened the door of the acclimatization cage, which resulted in Nuan dropping her baby, Namthip. This meant that we had to find a new territory for the group, much further away.

The move to the new site took place on the 7th of July 2007 and we opened the door for the second time on the 26th of September 2007. Staff and volunteers continued to observe this group every day for 3 months. They were all doing well, foraging, traveling together, vocalizing interaction between groups, as mentioned above, we have recently decreased the amount of supplementary feeding, as they appear to be foraging more and more for naturally occurring forest food.

Group Members...

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Payu group members.....Khao; father (1), Nuan; mother (2), Payu; sub adult male (3), Namthip; female offsping (4)

On the 29th of October 2008 Khao went missing, and although he was seen once again on the 5th of November, he disappeared again on the 6th of November 2008 and has not been seen since. The other three members remained in the forest and seemed to be doing okay without the Male.

On the 15th December 2008, Dao was found in Payu ’s territory playing with Payu and Namthip. Nuan was found not far from the group, she was sitting on the ground and she seemed weak and injured, unable to use her right hand for swinging at all. We concluded that she may have had a fight with Dao, as Dao had taken her place in the group, pairing up with Payu. We decided to catch her and bring her back to the rehabilitation site to treat the injury. When she recovered she was paired with Max and gave birth to two babies girl named “Maesa” on 12 April 2010 and “Emily” on 11 March 2011.

Payu, Dao and Namthip joined and formed a new group, still called Payu Group. This group has been doing well and we stopped the Supplemental feeding on the 7th of June 2009. On the 20th December 2009 our staff went to check on Payu group while on a routine feeding trip and found that Dao had just given birth to a male baby who we named Newbe-Mek which is now 21 months old.

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Payu, Dao and Namthip living together and formed a new group.....!! (1)

Newbe-Mek clinging on Dao's belly (2) Payu; new father (3)

Fourth group (Sixth Released) .... "Tony Group"

Tony Group (Tony; adult male, Jita; adult female and Claire; female infant) was moved into the acclimatization cage on the 29th November 2009.

However it seems that this group was eager to be free and did not want to wait for our planned release date. On the 4th of December when our staff went to feed the group they discovered the cage was empty - Tony had bitten through the mesh and the family had escaped! As we were not fully prepared for the release and follow up, we managed to entice Jita and Claire back inside the cage using food. Tony remained free but always stayed in the trees close to his family.

On the 10th December 2009, staff and volunteers trekked up to the release site and while Tony watched we opened the door of the cage. Jita hardly even hesitated before taking Claire and confidently exiting the cage, heading toward the food basket.

Group Members...

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Jita group members.....Tony; father (1), Jita; mother (2), Claire; female offsping (3)

After a release it is normal for Staff and Volunteers to spend all day every day in the forest following the released gibbons. the released gibbons will continue to be provided with supplementary food until we are sure they are able to find enough food on their own. We also spend time doing observation to check on their behaviour and generally make sure they are healthy and adapting well to life in the forest.

However with this family we had to change our plans as Tony was displaying a lot of aggression towards the observers. On the 14th of December one of the volunteers was bitten on her upper back and then on the 24th of December a staff member was bitten several times. We decided that while this behaviour was in a way normal – as Tony is trying to defend his territory and protect his family – it was too dangerous to spend a full day around the family as we needed to be constantly on guard. For now we continue to feed them every two days (0.5 kilogram of fruit) and spend some time watching their behaviour before going to check on the other released gibbon groups. Now Jita is missing and no record since the 29th March 2011.

Tony group......

Fifth group (Seventh Released) ...."Kushta group"

On the 10th of March 2006 we released a family of three gibbons Bozo; adult male, Kushta; adult female and Nat; infant male offspring, born at the Rehabilitation site. Unfortunately this release was unsuccessful as Bozo went missing just two days after the initial release, and despite our best efforts, was never found again and is presumed dead. It was decided to bring Kushta and Nat back to our rehabilitation site on the 12nd of April 2006. Nat remained with his mother and was a very healthy infant, larger than some gibbons at the Rehabilitation site who are twice his age. This is due to his being raised naturally by his mother and thus having received the necessary care and nutrition that those gibbons taken from the wild whilst still suckling sadly lack.. Nat was separated from Kushta at the end of 2008 to allow for the chance of another mating for Kushta, and was living with playmate Muki,  at the rehabilitation site. Kushta was introduced to one of the adult males, Mai, and they formed a successful pair, confirmed by the birth of their baby girl, Pee mai in January 2009. Sadly in May 2009 we discovered that Mai was losing his sight and we brought him back to live in our quarantine site for monitoring. Kushta and Pee Mai were introduced to Muki, who Kushta adopted and together with Nat they were taken into the forest to the training cage on January 30th 2011 in readiness to be released.

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Kushta group in training cage(1), Kushta; female (2), Nat; male offspring (3), Muki; male adopted (4), Peemai; female offspring (5), and Arun (6)

The family were released in April and May 2011. First, Kushta and Peemai were released on April 27th. The reason for this is that Arun had been at the training cage while the Kushta family were inside, and it was thought that Arun was looking for a mate. When Kushta and Peemai were released Arun did show interest in Kushta and was also very protective towards Peemai so it is very likely that Arun will become part of this family, he may pair with Kushta and make her family complete. Nat and Muki were released on May 2nd and all of the gibbons have taken to each other as well as their new environment.

They must be observed constantly for at least two weeks after release so staff and volunteers have been clearing trails so that the family can be tracked more easily (gibbons can travel through the trees at up to 25 metres). A camp site has also been prepared as a base for the observations. Now we still give food to them every day (4kg), gradually we will decrease and in soon let them trying to find food only by themselves. Some of them still being seen on the floor.

Since the released of Kushta family Arun moved to the Kushta Family. Before that he was already around the training cage. Kushta and Arun have been seen having sexual relation. On the 16th July 2011 Peemai went missing and found her agin on the 16th September 2011.

Other releases – Unsuccessful

"Yoge Group" .... Third Released

As detailed above, under description of second group (Lek Group).

Group Members of Yoge Group .....

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Yoge group members.....Bird; father (1), Pompam; mother (2), Sabai; sub adult female (3),Yoge; juvenile male (4)         

"Nat group" .... Fourth Released

As detailed above, under description of "Kushta group" which now were released.

Group Members of Nat Group

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Nat group members.....Bozo; father (1), Kushta and Nat; mother and male offspring (2)

Public relations, conservation education

Before and after the release, local residents were educated about the project and the release program. Flyers were distributed in the villages, especially in schools and to hunters, near the release site and people were asked to support the project by not disturbing the animals once they were in the forest. Signs were placed around the release site indicating that research was going on in the area.

Information on wildlife conservation has been distributed for ten years by GRP/WARF. At the east entry of the forest boards are installed indicating the goals of the project, the procedures and news about ongoing releases. At the same place local people and tourists are educated about conservation in general and funds are collected, mainly from foreign tourists. Film crews are allowed to go to the release site and document the re-introduction. Small groups of very interested people can also visit the animals in the forest.

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Last Update on 10 September 2011