Pilot Project: Release of Perth Zoo Orang-utan into Protected National Park

Background

The Sumatran Orang-utan (Pongo abelii) population (IUCN Critically Endangered) is less than 7% of what existed in 1900. There are approximately only 7,300 left in the wild and the current rate of loss is approximately 1,000 per year. Unfortunately 80% of the remaining orang-utan habitat is covered by timber concessions in the troubled province of Aceh.

Sumatran orangutans are the slowest reproducing species in the world. Females have their first infant at 15 years and then every nine years thereafter. Even if we could stop habitat destruction, without human intervention the recovery of the species would be approximately 0.006% per year. The re-introduction of orangutans from zoos has the potential to assist with the establishment of new orangutan populations and increasing gene diversity.

As the Sumatran orang-utan is Critically Endangered it is imperative that viable released populations are built up outside of the Aceh province. The Bukit Tigapuluh National Park (144,000 ha) contains the most intact examples of the entire mega fauna of Sumatra. However, although orangutans did historically occur in Bukit Tigapuluh (there are reliable reports of orangutans persisting in the area up until the 1830’s), they are now extinct in this area. Negotiations are currently near finalisation to expand the Park to at least 250,000 ha and there is also discussion about the park becoming a world heritage site.

The importance of Bukit Tigapuluh can’t be emphasised enough; Bukit Tigapuluh’s fauna contains the Sumatran tiger, Sumatran elephant, Sun Bear, tapir, probably still some Sumatran rhinos and, now, reintroduced Sumatran orangutan. These charismatic species upgrade Bukit Tigapuluh to the only National Park in Sumatra with a complete collection of the whole Sumatran mega fauna.

All logging and poaching activities within the Park boundaries have been stopped as a result of Orangutan Protections Units (OPU). The OPUs also monitor and guard reintroduced orangutans. A comprehensive orangutan reintroduction project has been established by the Sumatran Orangutan Conservation Programme (SOCP). Presently 100 orphaned and pet trade orangutans have been released into the national park as a part of a comprehensive reintroduction project of the SOCP. The aim of the project is to re-establish a viable orang-utan population in Bukit Tigapuluh. This is done with the agreement and support of the Indonesian Government.

Perth Zoo Involvement

Perth Zoo has one of the most successful breeding colonies of Sumatran orangutans in the world. Since 1970, 26 orangutans have been born at Perth Zoo and the colony currently comprises eight females and four males.

In recent years, Perth Zoo’s Curator of Exotic Mammals and Senior Primate Keeper have been instrumental in the Australian Orangutan Project (AOP) which has funded and supported conservation work at Bukit Tigapuluh National Park. This has assisted Perth Zoo in establishing strong links with Bukit Tigapuluh.

After much consideration and discussion about the conservation priority for such a strategy, as well as the safety of the release site, and with the endorsement of the Perth Zoo Board and the Western Australian Minister for the Environment, Perth Zoo embarked on a pilot project to release a suitable Perth Zoo-born orang-utan into this protected national park. The first release animal, Temara, was relocated from Perth Zoo to Indonesia in November 2006. 

Release Site

Bukit Tigapuluh National Park is an extremely important area of land. The protected area of Bukit Tigapuluh National Park is about 144,000 ha at present. Moreover, adjacent to the park’s boundaries are still considerable areas of forest in reasonably good condition. The whole remaining forest complex (including the protected area) encompasses at least 250,000 ha.

The SOCP estimates that the number of illegally kept Sumatran orangutans is around 200 to 400 individuals. SOCP Director Dr Peter Pratje of the Frankfurt Zoological Society conservatively estimates that the primary forest area within Bukit Tigapuluh has a carrying capacity of around 750 orangutans. The whole Bukit Tigapuluh forest block is ten times larger than the primary forest area and therefore has a much higher carrying capacity.
 
Bukit Tigapuluh National Park is located in the province of Jambi in eastern Sumatra. It is being used for a re-introduction project for orang-utans by the SOCP and 100 orangutans have been released since December 2002. It is planned to release around 20-25 orangutans per year over a 10-year period. The final goal of the project is to establish a viable Sumatran orangutan population in the Bukit Tigapuluh area. Trained professional Protection Units protect the National Park. Eight Orangutan Protection Units, are currently employed. To guarantee the success of the reintroduction programme, it is crucial that the Protection Units protect the national park habitat as well as prevent poaching of the orang-utans and other animals. Many local people are employed by this programme; local school programs are funded through the programme; and the Indonesian Government actively supports the project.

Previous Releases

The release programme run by the SOCP at Bukit Tigapuluh National Park has been successful. One hundred orphaned and ex-pet orangutans have been released at the site since December 2002 with a 77% survival rate. This is extremely high for orang-utan releases. All of these juvenile orangutans had lost their mothers and most had experienced physical and psychological trauma which has an impact on how they cope when released back into the forest.

Many of these young orangutans face a long rehabilitation process before release can be considered due to their unnatural upbringing. The survival rate is expected to increase as a result of changes to the release protocols since the first release. The main change has been reducing the number of orangutans released at the one time. The maximum number of orangutans now released at the one time is two as this ensures they can be observed and tracked fully for the initial release period.

The behaviour of an orangutan in the initial two weeks after release is often indicative of how they will cope in the future. If an orangutan adjusts well and is confident in the first week, then it will most likely flourish in the rainforest. If an orang-utan is unsure and stays near camp then it will take longer for the orang-utan to adapt to its new environment.

Over 10,000 hours of data has been recorded on released orangutans by local trackers who are employed and comprehensively trained by SOCP. The behaviour of the orangutans is recorded at two minute intervals to obtain a complete overview of their daily activity pattern. Orangutans are followed until they make a sleeping nest in the early evening. Trackers will then leave the nesting site and return early the following morning before the orang-utan has started to travel for the day so they can be followed again. Fruits and leaves that the orang-utans eat are also recorded. Once the Director of the project and the trackers feel confident that an orangutan is doing well and is self-sufficient, it will not be followed any longer. However, it will be recorded if this orangutan is encountered whilst another orang-utan is being followed.

Perth Zoo’s Temara

Temara was born on 14 September, 1992 to Puteri and Hsing Hsing. Temara was naturally raised by Puteri. Her older half sister, Utama was also housed with Puteri and Temara for numerous years.

At 14 years old Temara was at the natural age of dispersion (when an animal leaves its mother) for a female orang-utan. She has had a secure and nurturing upbringing and is an intelligent and independent orang-utan. Temara is active and shows good problem solving skills. She eats a wide variety of food and is always keen on her browse, fodder and feed. She is used to human company, however, was wary of keepers when they enter her exhibit for contact sessions. These are positive traits in terms of releasing an orang-utan. Temara’s intelligence and curiosity has encouraged her to explore the forest, travel and eat different foods including leaves. Her wariness of humans and independent nature assist her in not being reliant on the trackers for extra food.

As mentioned above, all of the juvenile orangutans released so far at Bukit Tigapuluh National Park have lost their mothers and have usually experienced physical and psychological trauma which has an impact on how they cope when released back into the forest. This is not the case with Temara. She has had a natural upbringing in terms of having the security of her mother for 13 years and given the opportunity to behave as a ‘normal’ orangutan. The orangutans at Perth Zoo are encouraged to perform natural behaviours such as nest building and using tools to obtain food. Temara has also had the opportunity to observe an infant orangutan being raised by his mother over the last year. This will greatly improve her chance of being a successful first time mother in the Sumatran rainforest. Psychological well being is the most important factor when releasing a captive or ex-pet orangutan and Temara is well equipped to handle the transition from a zoo environment to the rainforests of Sumatra.

Preparation in Captivity for Release

Orangutan keepers introduced changes to Temara’s diet and routine in preparation for her release. A wider variety of leaves and Indonesian fruits were introduced to her diet. She was also given smaller amounts of food every one to two hours during the day to mimic rainforest feeding patterns. Her vegetable ration was reduced and fodder (leaf) material increased to represent more closely what will be available to her in the Sumatran rainforest.

She was given extra vegetation to construct her sleeping nests rather than hessian sacks and cardboard and was given full access to the outside exhibit overnight to accustom her to sleeping outdoors. Live termites were introduced to her diet as these are readily available within Bukit Tigapuluh National Park. Temara had access to a mature 30m high fig tree for climbing and nest making. This improved her fitness and muscle tone to assist with the transition to tall rainforest trees. Hand injection and crate-training took place in preparation for her pre-shipment health check and transport.

The Release Process

Temara was 'soft-released' at Bukit Tigapuluh National Park. A 'soft-release' means an orang-utan is provided with additional back up food and is monitored once they are released. Perth Zoo’s Head Orangutan Keeper and Exotic Curator travelled with Temara to the National Park and was involved with the release. The head orangutan keeper stayed with Temara for an initial three month period as she acclimatised to her new environment.

Prior to release orangutans are kept in a large cage complex at the station to assess their personality and potential forest skills. Some orangutans are involved in a forest ‘playgroup’ where they are taken into the forest daily with keepers and encouraged to climb, feed on forest fruits and leaves and build nests. Temara was kept in the cage quarantine facility for the first two weeks so she had time to settle and become accustomed to the local temperature, wild fruits and leaves. Orangutans are only released during the fruiting season (November to January) to increase the amount of food available to them. Temara was released during this time with other compatible orangutans.

After the Release

Temara has been closely monitored by Perth Zoo and SOCP staff since her release in November 2006. She continues to be followed by the two SOCP staff members who are dedicated to tracking Temara. For more information on Temara's progress, click here for reports from the field.

Orangutan Open Sanctuary

SOCP Director Peter Pratje estimates that two out of every ten ex-pet orangutan do not fully acclimatize to independent life in the rainforest after two years.

To provide a better welfare and conservation outcome for these individuals, working with SOCP, Perth Zoo is developing an orangutan open sanctuary to care for these individuals in a rainforest setting near Bukit Tigapuluh National Park. These orangutans will be given daily care and supplementary feeding. Perth Zoo staff will be involved with training, care and husbandry of the animals. This is consistent with the Zoo’s position that its activities are not confined to the Perth Zoo site alone. It is anticipated that the animals at the open sanctuary will breed and their offspring will become fully wild orangutans within the park.

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