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Current Released Gibbons
Suggestion from our advisor, Dr.Warren Brokelman
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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.

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. Since 19th February 2004, we decided that the first 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 favour 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. The second group  (which now includes Yoge and Bank ) is still receiving food. As of May 2006 we reduced their food  to 1kg of fruit every second day.  

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(1) Feeding Basket for Released Gibbons
(2) Released Gibbons feeding from tree tops

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 time contained nothing at all (just the noise of it scared them of).
Human Aggression

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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(3-6) Observation and data collection

Current Released Gibbons

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 male baby, who we named Hope on the 21st October 2002.

On 26th October 2006, during the observation hour, our staff found that Kip has already given birth to her third baby. We can give an educated estimate of the date of birth as the 21st of October and do not sure yet about sex of new baby. The new baby was named "Toffee".

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. Things went much better after air-guns shooting small plastic pellets started to be used. After few experiences with the guns the gibbons learned to stay far from people pointing the plastic weapons towards 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.

Group members:

(Joe) (Kip)

(Thong) (Hope)

New born, Toffee

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 air gun, 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.
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. Currently they are being fed 1kg every second day and will hopefully soon be self sufficient.

Group Members          
            (Bird)    (Pompam)

(Sabai)  (yoge) 

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.

Group Members
                       (Bozo)  (Kushta and Nat)           

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 not disturbing the animals once they were in the forest. Signs were placed around the release site indicating that a research was going on in the area.

Information on wildlife conservation has been distributed for ten years by GRP. 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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References:

• PHUKET'S FOREST SINGS AGAIN, A survey of a group of white-handed gibbons (Hylobates lar) released in Khao Phra Theaw Non-Hunting Area, Phuket, Thailand (2004) by Damiana Ravasi
• Hermatolygy and blood chemisty associated with licer function to Hepatitis B Virus Disease in gibbon (Hylobates lar) (2003) by Yoopadee Wongsuptawee, Kulsiri Hanhabook and Srisucha Vongvisitsin
• An assessment the current reintroduction potential and planned release (1998) by Kersty Hobson
• Rehabilitated White-handed Gibbons (Hylobates lar) on Ko Boi Yai, Thailand (1996) by Casper J.Breuker