Hunting for meat and the illegal pet trade take an unusually high toll on orangutans.
Orangutans have the longest birth interval of any land mammal, with females usually producing no more than three or four babies in their lifetime. That makes them particularly sensitive to hunting pressure, with the loss of just one individual having a huge effect on the overall viability of a population.
Hunting and the use of orangutans for sustenance has always been a factor in Borneo and Sumatra, and traditional hunting by indigenous people has been responsible for a number of local extinctions. Although hunting by indigenous peoples for food is less of an issue today, a survey conducted in Kalimantan suggested up to 1,000 orangutans are still being lost every year to local hunting pressures (Meijaard, 2010). Research suggested that if local people no longer hunt orangutans, it was because they were so rarely seen, rather than because of any change in beliefs (Marshall et. al., 2006).
More troubling has been the more recent report of over 100,000 orangutans lost on Borneo during a 16 year period (1999-2015) as a result of killing outside of protected areas due to natural resource extraction with a large part of direct killing due to hunting from within forests (Voigt, et al. 2018).
Today, in the Malaysian state of Sarawak, orangutans are found mainly in areas where the Iban, the indigenous people of the area, have a taboo against the killing of orangutans. In areas where local people have no such taboo, orangutans are extinct. The eating of orangutans is also less common in areas where local people have converted to Islam, due to religious restrictions on eating meat.
The killing of orangutans by plantation workers, or by farmers who see them as pests, is still a serious issue, and the majority of orangutans currently in rehabilitation centers are orphans rescued from plantations after their mothers have been killed.
There have also been occasional reports from Aceh that suggest elements of the military have hunted orangutans for sport during the recent separatist conflict.
It has been illegal to own or trade orangutans in Indonesia and Malaysia for decades, but despite the substantial resources and media attention devoted to the issue, the trade in orangutans, predominantly infants, continues to flourish.
Although hunting is still an issue (see above) in both Indonesia and Malaysia, and illegal poaching does occur, most of the illegal trade in orangutans is a by-product of the destruction of the orangutan’s habitat. As the rainforest is cut down, terrified orangutans have nowhere to go and will descend to the ground, where they will usually encounter loggers or field workers. These orangutans, usually mothers with dependent offspring, are inevitably attacked, killed and eaten, their babies taken from them and either kept as pets or sold into the illegal animal trade.
Most infants don't survive the harsh journey to the wildlife markets in Jakarta, Bali, or other international locations. Poor care, disease, injury and the psychological trauma of losing their mothers means most captive infant orangutans don't survive their first year. It's estimated that for every orangutan that does survive, another six to eight die.
If an orangutan does survive the journey, for the first 2-3 years of their life they will make cute and appealing pets. However, by the age of 3 or 4, an orangutan will already be as strong as an adult human, and by the time an orangutan is approaching maturity at 10 years old, it will be between 5 and 7 times as strong as a male human. At this stage, most owners will keep the orangutan permanently caged, kill it or discard it. The lucky few will be confiscated.
There are currently over 1,500 hundred orangutans in rehabilitation centers in Borneo and Sumatra.
The impact of this trade is discussed in the UNEP Report "Last Stand of the Orangutan."
The illegal trade in wildlife has long been one of the most serious threats to the conservation of endangered species throughout the world, and, despite the large amounts of resources being spent on combating it and the huge publicity given to the animals most severely threatened by it, the pace of the trade continues unabated. Today, the illegal trade in wildlife is one of the world’s most lucrative illegal trades, with a combined value of around $10 billion dollars annually, and it has been estimated that the trade is, behind the international drugs trade, the world’s second-largest (Vince, 2002).
Primates are one of the most heavily traded types of wildlife and are traded for a variety of reasons, including for use as pets, for consumption, for use in biomedical research, traditional medicines, and for zoos, wildlife collections and the entertainment industry (Nijman, 2005). Most of the primate trade is illegal; however, some species are still traded legally. Historically, the most widely traded primate has been the macaque, which is used heavily in biomedical research, and an estimated 9,500 to 12,000 macaques enter the USA legally every year for use in research (WWF), with long-tailed macaques (Macaca fascicularis) still legally exported from Indonesia every year for this purpose (Soehartono & Mardiastuti, 2002).
Chimpanzees, bonobos, gorillas, gibbons, siamangs, and orangutans have long suffered from hunting pressures, and their continued presence in the illegal wildlife trade is considered one of their biggest threats while addressing these concerns is the focus of renewed attention (Shepherd, 2010).
Chimpanzees are perhaps the most famous of all the apes and have been traded illegally for decades, primarily for use as pets, and in the entertainment and biomedical research industries. Although the trade in wild chimpanzees is illegal and most countries either have or are now moving towards a ban in the use of great apes in invasive scientific experiments, there are currently around 1,300 chimpanzees housed in US laboratories, and they are all either wild-caught, or acquired from circuses, zoos or private collections (Project R&R). A further 113 are kept as pets in the USA, one of the few countries where keeping a great ape as a pet is legal. Although public pressure has seen the use of apes in entertainment decrease, until 2002, one of the most popular and successful advertising campaigns in the UK involved a group of chimpanzees, dressed as humans, drinking tea, a campaign which was voted the nations favorite in 2003 (The Guardian, 2003), and a pet gibbon recently featured prominently in a successful US comedy series. Throughout South East Asia, orangutans and gibbons, the only apes native to this part of the world, are found in tourist areas, often being forced to take part in boxing matches, or seen drinking alcohol and smoking cigarettes for tourists in nightclubs. Although proprietors claim these animals are captive born, they are more than likely poached from the wild (The Daily Mail, 2010).
Perhaps the biggest threat to the great apes of Africa is the increasing trade in the animals for human consumption, known as the bushmeat trade. Communities in Africa living in proximity to forested areas have always hunted chimpanzees, gorillas, and bonobos, and although there are local taboos, their meat has always been a staple of Central African diets. However, with the arrival of modern weapons, population growth, urban sprawl, and the opening up of Africa’s forests by timber companies, the consumption of ape meat has exploded from a pure subsistence activity, into a large commercial enterprise (Peterson, 2001). Today, it is estimated that up to 8,000 chimpanzees, bonobos, and gorillas are killed each year to fuel this industry (Bushmeat Project, 2010).
Orangutans, like all the other great apes, are listed on Appendix I of the Convention on International Trade in Endangered Species (CITES), which prohibits their unlicensed international trade, and, as signatories to CITES, Malaysia and Indonesia are required to adhere to this prohibition. Orangutans are also protected by national laws in both countries, initially introduced during their periods of European colonization, and amended upon independence. They are also members of the ASEAN Wildlife Enforcement Network (ASEAN), and Indonesia is a signatory to the Kinshasha Declaration, which resolves to improve “the protection of individual great apes and their habitats everywhere by demonstrably improving where necessary the quality and enforcement of relevant laws, as well as the capacity of law enforcement agencies” (CITES/GRASP, 2006). Despite this, the trade continues.
The orangutan trade encompasses many forms, but at its heart is the poaching of orangutans from the wild, be it for food, to obtain infants for the pet trade, for traditional medicine or in response to crop raiding (Rijksen & Meijaard, 1999).
One of the most complex issues in orangutan conservation is the hunting of orangutans by local people for food, something conservationists have often shied away from dealing with, for fear of offending local sensitivities. Fossil evidence from the Niah caves of Sarawak in Malaysia indicates humans were killing and eating orangutans as early as 40,000 years ago (Bennett, 1998), and, although different cultures have different taboos, the hunting of wild animals for sustenance has been, and still is, an integral part of indigenous cultures and rural life throughout Indonesia and Malaysia, with historic hunting seen as the likely explanation for the large areas of suitable forest habitat throughout Borneo currently devoid of wild orangutans (Rijksen & Meijaard, 1999). The introduction of both Christianity and Islam to the region has seen a modification in the beliefs and practices of many of the indigenous people, and today, most Muslim communities generally refrain from eating orangutan meat. However, there is still a large local variation in this activity, and whether or not orangutans are hunted is strongly linked with tribal and village identity (Marshall et. al., 2006). Surveys in Kalimantan have shown that hunting for meat claims the lives of around 1,000 orangutans a year (Mongabay, 2010), and studies have found that sustenance hunting was the primary factor reducing orangutan density in areas of Kalimantan, that orangutans were being killed not just for their meat, but for their perceived medicinal benefits of their body parts, and that any drop in the levels of hunting was due to the scarcity of orangutans today, rather than to any change in beliefs (Marshall et al, 2006). Research conducted by CITES and the Great Ape Survival Project (GRASP) in 2006 found that although the hunting of orangutans for their meat was not as widespread throughout Indonesia as the bushmeat trade is throughout Africa, orangutans are still widely hunted, and in some rural areas, some restaurants would prepare dishes containing orangutan meat, although these dishes would have to be specifically requested and would not be offered openly. They also found that orangutan fat and skin is used as a form of talisman to protect houses against fire.
Land conflict between wildlife and humans is not a new phenomenon and has occurred throughout the world since time immemorial. As a consequence of this conflict with population expansion and technology, the killing by humans has caused the extinction, or near extinction, of most large predators throughout Europe, North America and Australia. In the developing world, where large areas of tropical rainforest have been converted into agricultural land, such conflicts are an increasing problem. Although conflicts usually occur with larger, ground-dwelling animals like elephants and tigers, as the rate of deforestation in Indonesia and Malaysia has increased, so have human-orangutan conflicts, as starving displaced orangutans raid crops and wander into villages in search of food, where they are usually killed. One palm oil company in Central Kalimantan instigated a policy of paying local people 150,000 Rupiah (around $17) for every orangutan ‘pest’ killed (Buckland, 2005), and although a local NGO was able to form an agreement with this company in 2004 to rescue 52 adult and 11 infant orangutans found in their plantation, it is likely similar policies are in place in most other plantations. As firearms are not easily available, most orangutans in these situations are either beaten, hacked, drowned, set on fire, or buried alive (Schuster, 2007).
The illegal pet trade is one of the biggest threats to orangutans and is comprised of two components: the domestic market and the international market. The practice of keeping pets is widespread in many parts of Indonesia, and wildlife markets are a feature of most large towns and cities. Although illegal, the keeping of primates as pets is common (CITES/GRASP, 2006), and these primates, most often orangutans and gibbons, will often be kept by families, in good conditions, in the same way, people in western countries keep cats and dogs. In some circumstances, orangutans are also kept as status symbols, indicating an owner’s social status or wealth. Orangutans are also acquired by people for the sole reason of being illegal, and therefore a way for the owner to demonstrate that he or she is above the law. Investigations in Sumatra have shown that possession of orangutans is usually by local politicians, senior military and police staff, and many of the orangutans confiscated by the police and junior military will be used to curry favor with higher-ranking officials, with 60% of all orangutans in rehabilitation centers on the island having come from such sources (ibid).
Like all great apes, orangutans have slow life histories, and for the first few years of their lives, are docile, sweet and gentle. However, at around 5 years of age, an orangutan already has the strength of an adult male human, and by maturity, will be as strong as five to seven adult male humans, with an unpredictable and possibly aggressive nature that makes them unsuitable as pets.
The only way for an orangutan baby to be caught is for the mother to be shot, and the baby pried from her dead body. The route the baby then takes is entirely dependent on the intended form of trade, and how much money can be obtained. Almost every person living in a forested area of Kalimantan will know the value of a baby orangutan, so while poachers will sometimes keep orangutans for themselves, usually if the baby is kept by the poacher, or sold to a family in the same village, it is because the orangutan is a valuable commodity that can in time be sold or bartered (Nijman, 2005). Rather than being kept, it is more than likely that the baby will enter the illegal trade, usually sold to someone in another area, who will then sell it on for an increased price; the process becomes more and more professional and lucrative as it develops. The monetary value of an orangutan varies from place to place and depends on whether it is being sold in an area where orangutans live in the wild. For example, in Kalimantan, orangutans can be priced between 243,000-1,007,000 Rupiah ($27-$112), while on the island of Java, orangutans will cost more, from 3,462,000 Rupiah ($385). Orangutans are also often acquired in exchange for other commodities, such as a wristwatch or an electronic appliance (Nijman, 2005).
Orangutans are also often poached from the wild to form collections for zoos and wildlife parks throughout the country. The origins of the orangutans and other primates kept in these zoos are often uncertain, and records are not always kept, but it is likely few are captive-born. Conditions at these zoos are usually appalling, and have a high mortality rate; of the six orangutans present at the Medan zoo in Sumatra in 2006, only 2 were still there in 2008 (Nijman, 2009).
The international trade in orangutans is strictly prohibited, but despite its illegality, research into the illegal wildlife trade in Kalimantan and Sumatra has shown that orangutans are still being smuggled out of Indonesia into neighboring southeast Asian countries (Nijman, 2005; CITES/GRAS, 2006). Performing orangutans have always been extremely popular in South East Asia, and the similarities between infant orangutans and human babies have always made them popular household pets (Foead et. al., 2005). In the 1980s and 1990s, the illegal trade was focused mainly in the affluent country of Taiwan, where demand for orangutan pets was high, and to where an estimated 1,000 orangutans were illegally imported between 1985 and 1990 (WWF). In recent years, the large numbers of orangutans in Thailand and Cambodia has brought renewed attention to the wildlife trade, and their use in highly publicized kickboxing shows, aimed at domestic and international, usually western, tourists, has been the focus of intensive lobbying by NGOs.
In 2004, 114 orangutans were seized from the Safari World theme park in Bangkok, where they were forced to dress up and engage in Thai-boxing, and in 2006, 54 of these orangutans were returned to Indonesia. Unfortunately, the other 60 were believed to have died (Profauna, 2006). Despite the safari park being ordered to close, media reports surfaced in 2010 showing the park open and once again advertising orangutan boxing shows (Daily Mail, 2010). Orangutans are kept in similar parks in other areas of Thailand and Cambodia (Davies, 2005), with further groups of illegally imported orangutans known to exist in peninsular Malaysia, Saudi Arabia and Vietnam (CITES/GRASP, 2006). Like the domestic trade, these orangutans are poached from the rainforests, and transported to coastal towns, where they are often sold to crews of foreign-owned ships, and, through a system of corruption, bribes, and collusion, clear customs easily. Intelligence related to the illegal importation of one large shipment of orangutans from Kalimantan to Cambodia showed that a Thai fishing vessel had been involved (CITES/GRASP, 2006), and cargo ships are known to transport orangutans from the coastal city of Pontianak in west Kalimantan to Singapore (Nijman, 2005).
It is difficult to estimate the number of orangutans involved in the illegal domestic and international wildlife trade, or those lost to sustenance hunting, but it is evident that it is a considerable number. Between 1971 and 2004, 1433 orangutans were confiscated by forestry department officials in Kalimantan and placed in one of the 4 rehabilitation centers (Nijman, 2005); between 1973 and 2000, 226 orangutans were rescued and handed to the largest rehabilitation centre in Sumatra (Nijman, 2009). These numbers are likely just a drop in the ocean, but it is clear that if orangutans in Malaysia and Indonesia are to survive, stronger law enforcement is needed, and current domestic and international laws and treaties banning this trade are enforced.
Due to the illegal wildlife trade and the rate of deforestation in Indonesia and Malaysia over last 40 years, there has been an alarming increase in the number of orangutans in captivity - in zoos, wildlife parks, wildlife markets, and private homes, both domestically and internationally. As a result, conservation organizations are increasing efforts to rescue, rehabilitate, and release these orangutans. Ex-captive, wild-born orphans now represent a significant proportion of the surviving orangutan population.
Orangutan rehabilitation is complex and fraught with difficulties. It's currently one of the most controversial and hotly-debated aspects of orangutan conservation.
The first orangutan rehabilitation project began in the Malaysian state of Sarawak in the 1960s and was followed soon after by similar projects in Sabah in Malaysia, and Sumatra and Kalimantan in Indonesia, with the project in the latter, at Tanjung Puting National Park in Central Kalimantan, arguably being the most famous. At the time, little was known about the status of wild orangutans, the size of remaining populations, or even their life histories and ranges, as wild studies where then in their infancy, so rehabilitation methods were largely experimental.
Our partners the Sumatran Orangutan Conservation Program (SOCP) have run the world’s only Sumatran orangutan rehabilitation and release project since 2001. To date, it has cared for nearly 400 orangutans, releasing more than 180 of them back into the wild.
Although different project founders had their own motivations for establishing each program, they were usually initially set up to help enforce orangutan protection laws by providing legal holding facilities for confiscated orangutans, and, from an animal welfare perspective, giving orangutans confiscated from often appalling conditions a chance to once again live independently in the forest (Frey, 1978). Due to uncertainty over the number of orangutans living in the wild, rehabilitation programs in the 1970s placed an emphasis on releasing orangutans into areas with existing wild orangutans, to supplement populations that were considered too small to be viable (Russon, 2009). For example, at Tanjung Puting, between 1971 and 1994, at least 180 orangutans were released (Yeager, 1997) and at Bohorok in Gunung Leuser National Park in Sumatra, 218 orangutans were released between 1973 and 2000.
Most orangutans in rehabilitation centers were confiscated by forestry department officials. Occasionally they're handed in by people unable to look after them. The time spent in captivity and the age upon arrival vary, but most are confiscated when they are young, with between 63-97% of intakes under seven years old (Russon, 2009).
The living conditions in captivity also vary, but inadequate care under poor conditions is the most prevalent, and physical damage often includes gunshot and machete wounds, broken or missing limbs, scars and wounds from chaining, paralysis, blindness, and internal damage. Confiscated orangutans have also usually suffered extreme behavioral and psychological damage, including prolonged periods of isolation, physical and sexual abuse and abnormal associations with humans (Russon, 2009).
The behavioral abnormalities observed in ex-captive orangutans has been one of the most challenging aspects of the rehabilitation process, and has led to a divergence in the methods used, with some practitioners advocating limiting human contact severely, to try and remove learned human behaviors and encourage those seen in wild orangutans, while others believe orangutans, particularly infants and juveniles, should be assigned a human caregiver to teach them such behaviors, on account of the long period of dependence between a mother and infant in the wild. Regardless of the method used, almost all rehabilitation centers and release sites see abnormalities in released individuals. At Tanjung Puting, released orangutans occasionally attacked humans, others often reappeared at the release camp with deep wounds, indicating negative encounters with their wild counterparts, and others have been seen either ill or underweight (Yeager, 1997). Similar observations have been made at Bohorok in Gunung Leuser National Park (Dellatore et al, 2009). High infant mortality has also been observed in a number of release sites, indicating released ex-captive females lack the mothering skills of wild females (Russon, 2009).
The prevalence of diseases in ex-captive orangutans and the risk of these diseases spreading to wild populations is also a major concern. Ex-captive orangutans often carry human diseases such as hepatitis-a/b/c, tuberculosis, tetanus, respiratory disease, poliomyelitis and significant parasite loads (Russon, 2009), and while diseases are usually identified during a screening and quarantine period, there is a danger of these potentially fatal diseases being spread to wild populations if undetected. This threat has been exacerbated in recent years by the flourishing tourist trade that has developed around the ex-captive orangutans. Tourism and the revenue it raises is an incredibly important conservation tool, providing jobs and income for local people and governments, and a financial incentive to conserve wildlife. It is accepted that the large amounts of money tourists are willing to pay to see mountain gorillas in Central Arica is one of the main reasons for their continued conservation (Redmond, 2008), and there is a similar demand to see orangutans in the wild. However, unlike gorillas, which live terrestrially in large family groups, wild orangutans live solitary lives high up in the dense forest canopy and are difficult to observe from the forest floor.
Ex-captive orangutans, however, tend to spend extended periods on the ground, are more gregarious than their wild counterparts, and, due to their captive backgrounds, are usually comfortable around humans. Sepilok in the Malaysian state of Sabah, Bohorok, and Tanjung Puting all allow tourists to visit the ex-captive orangutan release sites, and, at the latter two sites, humans have been observed soliciting contact with the orangutans. Studies have shown that primate populations in close proximity to humans have higher levels of parasitic infection than those that rarely come in to contact, and our genetic closeness to orangutans makes them highly susceptible to human diseases (Wallis & Lee, 1999). It is feared that if an ex-captive orangutans were to catch a disease from a human tourist, it could decimate the wild populations, who do not have any natural immunity to human diseases. Although the semi-solitary nature of wild orangutans would usually restrict disease transmission (Galdikas, 1999), released ex-captives are more gregarious and, lacking the social skills they would learn from their mother, have been seen observed at Tanjung Puting soliciting play with wild females and their offspring, and climbing in and out of wild female’s day nests, while respiratory and skin diseases have been seen to be transmitted between individuals (Yeager, 1997).
To mitigate these problems, and in recognition of the fact that, due to an acceleration in deforestation, ex-captives were likely stressing wild populations and competing with them for food, the Indonesian government passed a law in 1995 restricting the release of ex-captive orangutans in to areas with a viable wild orangutan population, and aimed to restrict tourist activity at release sites. Today, although tourists can still visit the previously released ex-captives at Bohorok and Tanjung Puting, all confiscated orangutans are now quarantined and rehabilitated at specialist clinics, and released in to areas devoid of wild orangutans, or areas without a viable wild population, and closed to tourists, although such sites in both Indonesia and Malaysia are becoming almost impossible to locate. Most release projects also provide ‘soft releases’ for orangutans, where provisions and other supports are offered for a short period after the initial release, and in some cases, indefinite supplementary feeding is provided. Post-release monitoring of ex-captives has historically been difficult, due to a combination of lack of funds, the tough terrain and the orangutans wide-ranging patterns (Russon, 2009), but is hoped that new developments in microchipping technology could aid with post-release monitoring, and preventative measures could be taken to improve post-release mortality and success rates.
Despite these difficulties and ongoing problems, orangutan rehabilitation has also brought huge benefits and remains an important part of orangutan conservation and animal welfare. Continued deforestation and the illegal wildlife trade have caused orangutans being kept in appalling conditions throughout Indonesia and Malaysia, and often in other parts of the world. The existence of rehabilitation centers and the knowledge they will accept rescued individuals has provided impetus to forestry department officials to confiscate illegally owned orangutans, and these centers, all given the support of international NGO’s, are an essential facet of law enforcement (Russon, 2009). If rescue centers were not able to care for these ex-captives, they would likely die in captivity, in often appalling conditions; and while studies have shown that ex-captives have higher than average mortality and infant mortality rates (Russon, 2009; Yeager, 1997), it is also likely that a large number of those released into forests have survived and are living free, wild lives (Galdikas, 1999). Those orangutans not suitable for release are now often housed in sanctuary like enclosures in centers, where they enjoy a vastly improved quality of life, and at the Sumatran orangutan release site in the Bukit Tigapuluh landscape, a sanctuary for orangutans deemed unsuitable for rehabilitation has been developed in a semi-natural setting (Perth Zoo, 2009).
Rescue and rehabilitation projects are also important for the part they play in the relocation of wild orangutans from recently deforested areas to still forested areas, a process often referred to as translocation (Beck et. al., 2007). As the forest is cut down and orangutans are displaced, those that have been living independently in the forest, usually adults independent of their mothers, and have been captive for a just short period of time, often just a number of hours or days, can be relocated and released immediately into other areas of forest, without going through the rehabilitation process, limiting their exposure to human behaviors. Existing rescue and rehabilitation centers often provide the necessary logistical support and infrastructure to aid this work.
While the tourism industry brings with it complications, and the threat of humans infecting ex-captives and wild orangutans with human diseases remains an ever-present threat, it has also brought with it economic benefits, employment for local people and has helped create local, institutional and governmental support and commitment for orangutan conservation. (Galdikas, 1999). These easily accessible ex-captive orangutans have also made viewing orangutans in the wild possible for large numbers of people, and remain charismatic representatives of their under-siege species.
There is also evidence that the presence ex-captive orangutan release sites have, in some cases, strengthened the case for conserving the rainforest. The fall of President Soeharto from power in May 1998 after 32 years of dictatorial rule plunged Indonesia into political chaos, and vast areas of forest throughout the country were logged with impunity. Tanjung Puting National Park was overrun with illegal loggers (EIA, 1999), but the area in the vicinity of the most high profile release site in the park, known as Camp Leakey, an area with extensive local support and a high international profile, was left largely undisturbed (OFI, 1999). Two former logging concessions in Central Kalimantan that were to be turned into a palm oil plantation are now known as the Lamandau River Wildlife Reserve, which acts as a government-designated orangutan release site, after lobbying by NGO’s in the area, and surveys are currently underway to locate suitable release sites in West Kalimantan. Worldwide media attention has recently been given to plans by a pulp and paper company to convert a portion of the Bukit Tigapuluh landscape in Sumatra in to a plantation, with particular attention being paid to areas that act as a Sumatran orangutan release site, and the release of a zoo-born adult female from Perth Zoo in to this area in 2006 has ensured support for its continued protection from the West Australian government (Russon, 2009).
In 2007, the Indonesia government formulated an action plan for orangutan conservation, and one of its objectives was the release of all ex-captive orangutans and the closure of all current orangutan rehabilitation centers in the country by 2015 (MoF, 2009). Continued forest conversion, the illegal pet trade, the significant number of ex-captives currently in overcrowded rehabilitation centers and the difficulty in finding and securing suitable release sites means this is perhaps an optimistic timeframe, but securing an independent future for these wild-born, ex-captive orangutans nevertheless remains a hugely important part of the wider conservation movement.
Beck, B.B., Walkup, K., Rodrigues, M., Unwin, S., Travis, D. & Stoinski, T. (2007). Best practice guidelines for the reintroduction of Great apes. SSC Primate Specialist Group of the World Conservation Union, Gland, Switzerland.
Bennett, E. (1998). The natural history of the orangutan. Natural History Publications (Borneo).
Buckland, H. (2005). The oil for ape scandal. Friends of the Earth, UK.
Bushmeat Project. (2010). The Bushmeat Crisis. Bushmeat Project, UK.
CITES/GRASP. (2006). CITES/GRASP orangutan technical mission Indonesia. CITES/GRASP.
Davies, B. (2005). Black market. Inside the endangered species trade in Asia. Earth Aware Editions, USA.
Dellatore, D.F., Waitt, C.D. & Foitova, I. (2009). Two cases of mother-infant cannibalism in orangutans. Primates.
EIA. (1999). The Final Cut. Environmental Investigation Agency, UK.
OFI. (1999). A message from Dr Galdikas. Orangutan Foundation International, Red Ape newsletter.
Foead, N., Elliott, W., Ziegler, S., Van Gool, M. & Nijman, V. (2005). WWF’s species action plan for the conservation of orangutans in the wild.WWF's Species Action Plan, UK.
Frey R. (1978). Management of Orangutans. BIOTROP Special Publication.
Galdikas B. (1999). Orangutan Odyssey. Harry N. Abrams, USA.
Marshall, A.J., Nardiyono., Engstrom, L.M., Pamungkas, B., Palapa, J., Meijaard, E. & Stanley, S.A. (2006). The blowgun is mightier than the chainsaw in determining population density of Bornean orangutans (Pongo pygmaeus morio) in the forests of East Kalimantan. Biological Conservation, 129, pp. 566-578.
Meijaard E. (2010). Indonesian people-not international donors or orangutan conservationists-will determine the ultimate fate of Indonesia's forests. Mongabay.com.
Nijman, V. (2005). Hanging in the Balance. An assessment of trade in orangutans and gibbons in Kalimantan, Indonesia. TRAFFIC, Southeast Asia.
Nijman, V. (2009). An assessment of trade in orangutans and gibbons in Sumatra, Indonesia. TRAFFIC, Southeast Asia.
Perth Zoo. (2009). Perth Zoo’s work in Bukit Tigapuluh. website.
Peterson, D. (2001). Eating apes. University of California Press, USA.
ProFauna. (2006). Indonesia welcomes home orangutans. Profauna.
Redmond I. (2008). The Primate Family Tree. Firefly Books Ltd, UK.
Rijksen H. & Meijaard E. (1999). Our vanishing relative. The status of wild orangutans at the turn of the 20th century. Kluwer academic Publishers, Netherlands.
Russon, A.E. (2009). Orangutan rehabilitation and reintroduction. In Wich, S.A., Utami Atmoko, S.S., Mitra Setia, T. & Van Schaik, C.P. editors. Orangutans: Geographic Variation in Behavioral Ecology and Conservation. Oxford University Press.
Schuster, G. (2007). Thinkers of the jungle. Tandem Verlag GmbH, Germany.
Shepherd, C. (2010). Illegal primate trade in Indonesia exemplified by surveys carried out over a decade in North Sumatra. Endangered Species Research
Soehartono, T. & Mardiastuti, A. (2002). CITES implementation in Indonesia. CITES.
The Daily Mail. (2010). Orangutans kickbox and parade in bikinis for cheering tourists. The Daily Mail.
The Guardian. (2003). Gone but not forgotten. The Guardian.
UNEP. Last Stand of the Orangutan. http://www.unep-wcmc.org/last-stand-orangutan_127.html.
Vince, G. (2002). Organized gangs target wildlife trade. New Scientist.
Wallis, J. & Lee, D.R. (1999). Primate conservation: The prevention of disease transmission. International Journal of Primatology, Vol 20, 6, pp. 803-826.
WWF. (2008). Sumatra. WWF.
WWF (2009). APP's forest clearing linked to twelve years of human and tiger deaths in Sumatra. WWF.
Voigt, M. (et. al.) (2018) Global Demand for Natural Resources Eliminated More Than 100,000 Bornean Orangutans. Current Biology, https://doi.org/10.1016/j.cub.2018.01.053
Yeager, C.P. (1997). Orangutan rehabilitation in Tanjung Puting National Park, Indonesia. Conservation Biology, Vol. 11, No. 3, pp. 802-805.