tourists-mtgorilla-guardian   Tourism is one of the world’s fastest growing industries, and ecotourism has emerged as one of its leading sectors, estimated to be growing at a rate of between 10% and 15% per year (Matthews, 2002). Ecotourism has been defined as travel to natural areas that conserves the natural environment and helps the local people (Chin et al, 2000), and is seen increasingly as a significant tool in the conservation of endangered species, by providing local people with economic alternatives to resource exploitation (Nakamura & Nishida, 2009), raising living standards (Matthews, 2002), providing awareness and financial support for conservation (Ash, 2006) and financing protected areas (Wilkie & Carpenter, 1999). Although ecotourism has enjoyed broad support as a conservation tool, concerns have been raised that the development of tourism can negatively impact on the environment, by the development of urban infrastructure, can cause stress to animals and affect their behaviour and cause social problems for local people (Roe et al, 1997).

Ecotourism has become an increasingly popular tool in the conservation of the great apes, which are all either endangered or critically endangered in the wild (Beck et al, 2001, cited in Nakamura & Nishida, 2009). In Africa, ecotourism has involved habituating groups of wild gorillas and chimpanzees to human observers (Nakamura & Nishida, 2009), and such projects have thrived; In Uganda, tourism has become the principal source of foreign exchange, and gorilla and chimpanzee viewing is responsible for 52% of tourism revenue (Wrangham, 2008, cited in Nakamura & Nishida, 2009).


In Indonesia and Malaysia, home to the only remaining populations of orangutans, ecotourism has taken a different approach. Unlike chimpanzees and gorillas, which live in large social groups and spend a significant proportion of their time on the ground (Redmond, 2008), orangutans are semi-solitary and almost strictly arboreal (Gladikas, 1985). As such, they are difficult to find and observe from the ground, and even when found, have often been accused by tourists of being boring (pers. obs), on account of their slow activity patterns; orangutans in some areas spend 60.1% of their time foraging and eating, and 18.2% resting (Gladikas, 1988). Instead, tourism most often revolves around ex-captive orangutans, which are often more social than those in the wild (Yeager, 1997), and spend more time on the ground and in association with conspecifics (Snaith, 1999). Hence, they are often easier for tourists to see.


ecotouristtpnp1Tanjung Puting National Park is a 416,000 hectare park in the province of Central Kalimantan. The park hosts a wide variety of biodiversity (Brend, 2006), but is most famous for its population of Bornean orangutans; the park was estimated to comprise a population of 6000 individuals in 2004 (Singleton et al, 2004), though it is possibly less now. Orangutan rehabilitation began in Tanjung Puting in 1971, concentrated around the Camp Leakey study area (Galdikas, 1982). Ninety orangutans were released there between 1971 and 1985 (Galdikas & Ashbury, 2012), and possibly as many as 180 up to 1994 (Yeager, 1997), when orangutan rehabilitation began being moved to other areas. Today, tourists can visit ex-captive orangutans at 3 areas in the park, Camp Leakey, Tanjung Harapan and Pondok Tanggui (Brend, 2006), where orangutans are given a daily supply of milk and fruit daily at a feeding and viewing platform (Galdikas & Ashbury, 2012). Although Tanjung Puting contains a large wild population and some wild individuals visit the feeding platforms (Ibid), most tourists will only see ex-captive orangutans and their offspring (pers. obs).


Bukit Lawang is a former orangutan rehabilitation centre situated in the Gunung Leuser National Park in Sumatra, an 830,000 hectare park situated in the Leuser Ecosystem (Dellatore, 2007; Singleton et al, 2004). Bukit Lawang acted as a Sumatran orangutan (Pongo abeli) rehabilitation project between 1972 and 1991, with 227 orangutans being associated with the project, though 51 are confirmed as having died (Dellatore, 2007). Orangutans are no longer rehabilitated at the centre, but the area remains home to a number of ex-captive orangutans and their offspring, who receive supplementary feedings of fruit and milk twice a day at a feeding platform attended by tourists (Ibid). Official Forestry Department figures show 206,963 foreign tourists visited Bukit Lawang between 1985 and 2003, an average of 10,893 per year, and 5,800 domestic tourists visited per year between 1990 and 2003 (Ibid). In total, 288,165 people visited this site in 18 years, though this might be less than half the real figure if unregistered visitors are taken in to account (Rijksen & Meijaard, 1999, cited in Dellatore, 2007).


ecotouristtpnp2The ex-captive tourist sites in both Tanjung Puting and Gunung Leuser remain controversial (Russon, 2009), and there have been longstanding fears about the effects such high densities of people have on the orangutans. In both national parks, tourists have been observed soliciting contact with orangutans, stroking them, trying to touch infants leading to aggressive encounters with mothers, shaking trees to get an orangutans attention and taunting them with fruit (pers. obs), and similar behaviours have been seen elsewhere; Bowden, 1980 reports seeing ex-captive orangutans at Sepilok in Malaysian Borneo being approached by humans, offered food, being touched, harassed, hit and kicked (cited in Snaith, 2009), and Yeager, 1997 reports that 3 released individuals in Tanjung Puting were recaptured and released in to other areas after aggressive encounters with humans.


The close proximity of humans and orangutans at such tourist sites remains a concern; the close phylogenetic relationship between humans and non-human primates means pathogen exchange is a risk (Gillespie et al, 2008), and the great apes are particularly susceptible (Homsy, 1999). A number of cases of illnesses in apes have been shown to be linked to human respiratory viruses and bacteria, including influenza, measles, mumps, pneumococcal pneumonia and herpes viruses (Ibid), and in the Virunga volcanoes in Africa, over 81% of gorillas in 7 groups used for research and tourism purposes suffered from an influenza-like disease, with 6 adults dying from it in 1988 alone (Reynolds, 2006, cited in Isabirye-Basuta & Lwanga, 2008).


Surveys at the Sepilok orangutan rehabilitation centre in Malaysia show that a significant portion of tourists that visit this centre, which totalled 97,367 in 2006 (Muehlenbein et al, 2010), are ill and potentially infectious at the time they visit, and risked infecting the animals, local inhabitants of the area and Sepilok rangers (Ibid). Such diseases not only pose a threat to the ex-captive orangutans, but risk spreading to the wild populations, which would have no such natural resistance. Although authors have argued that the largely solitary nature of wild orangutans would inhibit disease transmission (Galdikas & Briggs, 1999), ex-captive orangutans at Tanjung Puting have been shown to be social, often travel together, and have been observed soliciting play with wild females and their offspring and climbing in and out of their nests (Yeager, 1997), and that ex-captives are exposed to human diseases and that respiratory diseases and skin infections have been transmitted between individuals (Ibid).


The risk of behavioural changes in wildlife also remains a concern at ecotourism sites. Bukit Lawang, Sepilok and Tanjung Puting all report higher infant mortality in the offspring of ex-captives than is seen in wild orangutans (Dellatore et al, 2009; Russon, 2009), and cases of ex-captive females at Bukit Lawang cannibalising their offspring, a previously undocumented behaviour in wild orangutans, may have been influenced by stress caused by the high concentration of humans in the area (Dellatore et al, 2009).


Modifications in primate behaviour are seen in numerous other primate ecotourism sites. An examination of the impacts tourists have had on wild howler monkeys in the 400 hectare Lamanai Archaeological Reserve in Belize, which attracted 21,499 visitors in 2000 (Grossberg et al, 2003), has shown that 25% of all tourists have observed other tourists or guides interacting with howler monkeys, shaking branches, trying to make them roar, offering food or making physical contact with them (Ibid), and that such provocation disrupted activity patterns, with juveniles, females and infants avoiding provocation by moving higher in to the canopy, while adult and sub-adult males responded by roaring or approaching the humans, moving to the ground to bite people, or grabbing bags (Ibid). Intense roaring against humans has also provoked neighbouring howler monkey groups to either roar back or approach (Ibid). As howler monkeys are highly territorial, spend the majority of their time in the trees, roaring is believed to act as spacing mechanism, and competition between adult males is intense (Redmond, 2008; Di Fore & Campbell, 2007), such behaviour is a concern.


Instances of primates descending to the ground and biting or attacking humans have been observed at a number of primate ecotourism sites (Fuentes et al, 2007), and often involves provisioning of food, which can increase levels of aggression (Westin, 2007; Hsu et al, 2009). In India, monkeys around Hindu temples are given hand-outs by local people and tourists, and often become aggressive when food is denied, tearing clothes, biting, and raiding pantries and hotel rooms (Wolfe, 2002, cited in Westin, 2007). In Tanzania, vervet monkeys have been seen waiting at picnic tables and public toilets to ambush tourists to take their food (Ibid). Fuentes et al, 2007 found that at the Padangtegal Hindu temple on the Indonesian island of Bali, the strongest enticement for contact between tourists and the resident long-tailed macaques was the presence of food or the suggestion of it, in the form of plastic bags or items wrapped in banana leaves, and though there are signs warning tourists against feeding, such aggressive encounters are common, with 11.4% resulting in bites.


macaquechina5ftoffgroundMacaques have the widest distribution of any non-human primate (Thierry, 2007), and their home ranges frequently overlap with humans and tourist sites (Fuentes, 2004). Conflict between humans and macaques often leads to injury in both species, and there is a great risk of disease transmission; macaques can carry diseases that can transfer to humans, including simian foamy virus, herpes B and simian retrovirus, and humans carry influenza and respiratory pathogens that can spread to macaques (McCarthy et al, 2009). Wild Tibetan macaques can be seen by tourists at two sites in China, Mt. Emei and Mt. Huangshan. Examinations in to macaque-human interactions at these sites shows that humans initiate contact with macaques far more than macaques do with humans, with pointing, waving, making facial threats and slapping the railings the most common observed human behaviours (Ibid). Although humans and macaques were found to provoke each other, many of the human behaviours observed were repeated, indicating tourists were deliberately antagonising macaques and waiting for a reaction (Ibid). The macaques at Mt. Emei regularly rob food and other possessions from visitors, injuries are common and 10 people even died in a period of 8 years as a result of conflict encounters (Ibid). Such observations have also been seen at macaque tourist sites in Taiwan and Gibraltar, where humans initiate contact with the monkeys far more than macaques do with humans (Ibid; Hsu et al, 2009).



gibraltarbarbarymacaque-wikipediaAggressive primate encounters can not only be a danger to the tourists involved, but the increasing habituation of primates and corresponding boldness can create problems for local people; monkeys that have been habituated to the presence of tourists often seek out contact with humans, and raid crops and garbage bins (Muehlenbein et al, 2010). In Gibraltar, the increase in tourist activity around the resident Barbary macaques from 1960 onwards, to around 800,000 people per year, led to a rise in illegal provisioning, and taxi drivers and tour guides encouraging closer interactions between macaques and tourists, often so tourists could get better photos (Fuentes et al, 2007). Today, people in the tourist industry have a vested interest in conserving the macaques, but many residents in Gibraltar complain that they raid bins and occasionally kitchens looking for food, and have actively called for them to be removed and for some to be culled (Ibid).


Local people often suffering as a result of conservation projects is not a new phenomenon; the development of national parks and protected areas have traditionally excluded local people from those areas, effecting their income and traditional subsistence methods, and creating negative attitudes to conservation (Hartter & Goldman, 2010). Ecotourism has aimed to rectify this, however, by bringing economic benefits to local communities.


Kibale National Park is a 79,500 hectare park in Western Uganda (Hartter, 2009) and its population of wild chimpanzees attract tourists to the area (Lepp, 2008), which is one of the most densely populated in Sub-Saharan Africa (Lepp & Holland, 2006), with 262 individuals per km2 on the west side of the park, and 335 individual per km2 on the east side (Hartter, 2009). The predominant subsistence crops in the area are bananas, maize, beans and cassava (Ibid). Authors working in the area have shown that 74% of local people have reported problems with crop raiding and wild animals killing small livestock, with red-tail and vervet monkeys the most common nuisance animal, with other species of monkey and elephants also cited as problems (Ibid). A tourism project has been developed in the small, rural village of Bigodi, which borders the park, which attracts an average of 75 tourists per month and centres on an area of swampland which had always been considered a nuisance to locals but offers visitors a perfect view of different species of monkeys and birds (Lepp, 2008). Despite the high levels of poverty in the area and the need for income, residents were initially deeply anxious of allowing tourists in to their community, and considered the project a plan by westerners to steal land and resources (Ibid). Although residents’ views have since warmed to tourism, conservation of the swamp has seen wildlife increase and a corresponding increase in the levels of crop raiding (Ibid). Although tourism has been successful and provides employment for young men, farming is still the principal subsistence strategy in the village, and crop raiding therefore not only threatens people’s subsistence and economic activities, but has been noted to effect education in the village, as children are made to miss school to guard crops (Ibid).


Such findings are not isolated. More than one million people visit Costa Rica every year, and the tourism industry is heavily promoted and has an annual turnover of over $1,200 million (Koens et al, 2009). Nature tourism in the country is considered successful, but an examination of four tourist sites in Costa Rica found that, at two sites, the development of infrastructure for tourism purposes had resulted in vegetation damage, disturbance to wildlife, and had increased the risk of erosion, with a corresponding loss of biodiversity, and air pollution had increased as a result of higher numbers of vehicles entering the area (Ibid). The economic improvements tourism can bring vary depending on who owns accommodation and services used, and whether money stays in the area, but an increase in tourism was seen to bring increased education, medical care and increased levels of female empowerment (Ibid), although community organisation had diminished, alcohol and drug consumption had increased and some areas had seen in an increase in crime (Ibid).


The examples shown in this article demonstrate some of the challenges and complexities inherent in tourism involving species that are often endangered and highly intelligent, opportunistic and capable of aggression (Hadiswoyo, 2008) and live in areas of high human densities and low economic activity. They are not, however, representative of all primate ecotourism projects.


Great ape ecotourism remains challenging, and as demonstrated by Tanjung Puting and Bukit Lawang, is difficult when the subject is an ex-captive, but tourism with other great apes has had some notable successes; tourism is regarded as one of the reasons the number of mountain gorillas are increasing (Redmond, 2008), and gorilla trekking is the most popular activity for international tourists travelling to Rwanda (Spenceley et al, 2010), with 16,937 people travelling to the Virunga National Park in 2008 to see the gorillas (Ibid). The tourism industry around this park in Rwanda is estimated to be around $42.7 million, in terms of turnover for accommodation, tour operators, shopping and other excursions, and the park itself directly employs at least 180 people (Ibid). The success of gorilla tourism, in business terms, and the increasing economic viability of the mountain gorilla population have led protecting them to be considered economically important for the government and local businesses (Redmond, 2008). Such an attitude has also been seen in Tanjung Puting in Indonesia, which suffered widespread logging during the crisis that followed the resignation of General Soeharto in 1998; at its height, it is believed up to 800 ramin wood logs were being taken out of the park every day (EIA, 2003). The only part of the park that remained relatively undisturbed was the Camp Leakey study area, the principal tourist area in the park (OFI, 1999; G. Shapiro, personal communication).


The threat of disease transmission remains a concern in all areas where humans and non-human primates come in to contact; as well as habituated gorillas, chimpanzees living at the famous Gombe National Park in Tanzania have been shown to be at risk of tuberculosis from people, and have suffered in the past from polio and a respiratory disease that killed 11 chimpanzees (Wallis & Lee, 1999), and a female researcher in the Ivory Coast caught the Ebola virus from an infected chimpanzee in 1994 (Goldberg et al, 2007). While exposure at tourism sites is always a risk, it could be reduced by the enforcement of existing rules that govern primate viewing, or strengthening of those that are unsatisfactory; Homsy, 1999, recommends limiting the number of visits to gorillas, reducing the number of tourists per group, increasing the distance between humans and gorillas, enforcing rules on eating, litter and faeces disposal and stronger enforcement of rules forbidding tourists exhibiting illnesses.


Enforcing existing rules would also help mitigate aggressive encounters at sites involving monkeys. All reserves in Gibraltar that house macaques have signs stating that feeding them is illegal, punishable by a £500 fine, and warning humans of potential dangers (Fuentes et al, 2007). In Bali, while staff tentatively try and discourage contact between humans and macaques, they rarely directly intercede, unless aggression occurs (Ibid). Singapore has an education and awareness programme in areas where humans and macaques come in to contact, and sometimes enforces fines and penalties for people caught feeding them (McCarthy et al, 2009). As interactions have been shown to be more aggressive when food is involved, similar rules and enforcement should be developed at all ecotourism sites. Enforcement of rules is often difficult for park rangers, for cultural reasons (pers. obs), and could possibly lead to arguments with tourists, but strongly regulated tourist sites would likely decrease aggressive encounters and make primate viewing a much safer activity; Grossberg et al, 2003 specifically recommend education and enforcement as a way of reducing human-howler monkey conflict in Belize.


The greatest success for ecotourism projects will likely come from the involvement of local people. Increasing efforts have been made to ensure local people benefit from wildlife tourism (Aharikundira & Tweheyo, 2011), but communities adjacent to protected areas still suffer from high levels of conflict and, particularly, crop raiding (Ibid; Distefano, 2005). Bwindi National Park in Uganda has a large population of mountain gorillas and a lucrative tourism trade, but habituated gorillas regularly raid local farms (Aharikundira & Tweheyo, 2011). To mitigate this conflict, gorilla conservation organisations have organised special response units to help protect crops and limit retaliatory action, which authors show have reduced raiding and attacks on humans (Ibid). Such projects enjoy community support (Ibid). However, local people complain that park authorities are so focused on gorillas that they remain indifferent to crop damage by other animals, which is often more severe (Ibid).


As the case studies have shown, primate tourism sites can often bring development which negatively impacts on the environment, and the influx of large amounts of people can change traditional cultural and social behaviours, lead to an increase in crime, and can lead to an increase in prices that exclude local people from areas they have traditionally used (Koens et al, 2009). However, they have been shown to also bring medical facilities and increased education (Ibid) and can help the poor; revenue from tourism in Rwanda has not only helped alleviate poverty and provide employment (Spenceley et al, 2010) but has also contributed to reconciliation and peace in the country (Alluri, 2009).


An examination in to ecotourism sites worldwide by Matthews, 2002 showed that the most successful ecotourism projects were those with the most efficient management structure, that efficiency was improved by the involvement and training of local people, and that resources had to be shared equally to improve attitudes to conservation areas and reduce conflict in and between communities, and that those sites struggling with community support were those lacking community development projects, had inefficient management and where resources were denied to local people and revenue was often taken out of the area. This research is corroborated by evidence from the macaque tourist sites in Bali and Gibraltar; in Bali, despite aggressive encounters and instances of crop raiding, local people remain tolerant of the macaques and supportive of the ecotourism project, largely because the majority of tourism revenue remains in the village and is distributed by the village council for infrastructure and cultural projects, while in Gibraltar, a richer and more developed area, the government receives all entrance fees and revenue from the tourist sites, and local support has wavered (Fuentes et al, 2007).


On paper, ecotourism can appear relatively simple. In reality, it is a difficult process that in many cases struggles to combine habitat and wildlife conservation with the reasonable expectations and needs of the local people who depend on that habitat, and often come in to conflict with its wildlife. Only by including local people in the conception and management of ecotourism projects and making sure revenue is distributed equally can such projects be successful, and only by eco-tourists strictly adhering to the rules and regulations of tourism sites can such sites fully safeguard animals from diseases, abnormal behavioural changes and heightened levels of aggression.







Aharikundira, M. & Tweheyo, M. (2011). Human-wildlife conflict and its implication for conservation around Bwindi Impenetrable National Park. USDA Forest Service Proceedings


Alluri, R.M. (2009). The role of tourism in post-conflict Rwanda. Working Paper, Swiss Peace Foundation


Ash, G.L. (2006). Ecotourism and interpretation in Sri Lanka: visitor perceptions of the local primates. MsC dissertation. Oxford Brookes University


Brend, S. (2006). Tanjung Putting National Park: Orangutans and their habitat. The Orangutan Foundation & Yayorin


Chin, C.L.M., Moore, S.A, Wallington, T.J. & Dowling, R.K. (2000). Ecotourism in Bako National Park, Borneo: Visitors’ perspectives on environmental impacts and their management. Journal of Sustainable Tourism, 8, pp. 20-35


Dellatore, D.F. (2007). Behavioural health of reintroduced orangutans (Pongo abeli) in Bukit Lawang, Sumatra, Indonesia. MSc thesis, Oxford Brookes University


Dellatore, D.F., Waitt, C.D. & Foitova, I. (2009). Two cases of mother-infant cannibalism in orangutans. Primates


Di Fiore, A. & Campbell, C.J. (2007). The atelines: variation in ecology, behaviour and social organisation. 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


Distefano, E. (2005). Human-wildlife conflict worldwide: collection of case studies, analysis of management strategies and good practices. Food and Agricultural Organisation of the United Nations, Rome


EIA. (2003). Illegal logging in Tanjung Puting National Park. Environmental Investigation Agency


Fuentes, A. (2004). Is monkey business a valid enterprise? The political ecology of macaque ‘ecotourism’. Folia Primatologica, 75, pp. 43-44


Fuentes, A., Shaw, E. & Cortes, J. (2007). Qualitative assessment of macaque tourist sites in Padangtegal, Bali, Indonesia and the Upper Rock Nature Reserve, Gibraltar. International Journal of Primatology


Galdikas, B.M.F. (1982). Orangutan tool use at Tanjung Puting Reserve, Central Indonesian Borneo (Kalimantan Tengah). Journal of Human Evolution, 10, pp. 19-33


Galdikas, B.M.F. (1988). Orangutan diet, range and activity at Tanjung Puting, Central Borneo. International Journal of Primatology, Vol. 9, No. 1


Galdikas, B.M.F. (1985). Orangutan sociality at Tanjung Puting. American Journal of Primatology, 9, pp. 101-119


Galdikas, B.M. & Ashbury, A. (2012). Reproductive parameters of female orangutans (Pongo pygmaeus wurmbii) 1971-2011, a 40 year study at Tanjung Puting National Park, Central Kalimantan, Indonesia. Primates


Galdikas, B.M.F & Briggs, N. (1999). Orangutan odyssey. Harry N. Abrams, Inc, USA


Gillespie, T.R., Nunn, C.L. & Leendertz, F.H. (2008). Integrative approaches to the study of primate infectious diseases: Implications for biodiversity conservation and global health. Yearbook of Physical Anthropology, 51, pp. 53-69


Goldberg, T.L., Gillespie, T.R., Rwego, I.B., Wheeler, E., Estoff, E.L. & Chapman, C.A. (2007). Patterns of gastrointestinal bacterial exchange between chimpanzees and humans involved in research and tourism in western Uganda. Biological Conservation, 135, pp. 511-517


Grossberg, R., Treves, A. & Naughton-Treves, L. (2003). The incidental ecotourist: measuring visitor impacts on endangered howler monkeys at a Belizean archaeological site. Environmental Conservation, 30 (1), pp. 40-51


Hartter, J. (2009). Attitudes of rural communities towards wetlands and forest fragments around Kibale National Park, Uganda. Human Dimensions of Wildlife, 14, pp. 433-447


Hartter, J. & Goldman, A. (2010). Local responses to a forest park in western Uganda: alternative narratives on fortress conservation. Oryx, 45, pp. 60-68


Homsy, J. (1999). Ape tourism and human diseases: How close should we get?. Report of a Consultancy for the International Gorilla Conservation Programme


Hsu, M.J., Kao, C.C. & Agoramoorthy, G. (2009). Interactions between visitors and Formosan macaques (Macaca cyclopis) at Shou-Shan Nature Park, Taiwan. American Journal of Primatology, 71, pp. 214-222


Isabirye-Basuta, G.M. & Lwanga, J.S. (2008). Primate populations and their interactions with changing habitats. International Journal of Primatology, 29, pp. 35-48


Koens, J.F., Dieperink, C. & Miranda, M. (2009). Ecotourism as a development strategy: experiences from Costa Rica. Environment, Development and Sustainability, 11, pp.1225-1237


Lepp, A. (2008). Attitudes toward initial tourism development in a community with no prior tourism experience: the case of Bigodi, Uganda. Journal of Sustainable Tourism, Vol. 16, No. 1


Lepp, A. & Holland, S. (2006). A comparison of attitudes towards state led conservation and community based conservation in the village of Bigodi, Uganda. Society and Natural Resources, 19, pp. 609-623


Matthews, E.J. (2002). Ecotourism: Are current practices delivering desired outcomes? A comparative case study analysis. MA thesis. Virginia Polytechnic Institute & State University


McCarthy, M.S., Matheson, M.D., Lester, J.D., Sheeran, L.K., Li, J.H. & Wagner, R.S. (2009). Sequences of Tibetan macaque (Macaca thibetana) and tourist behaviour at Mt. Huangshan, China. Primate Conservation, 24, pp. 145-151


Muehlenbein, M.P., Martinez, L.A., Lemke, A.A., Ambu, L., Nathan, S., Alsisto, S., & Sakong, R. (2010). Unhealthy travellers present challenges to sustainable primate ecotourism. Travel Medicine and Infectious Disease, 8, pp. 169-175


Nakamura, M. & Nishida, T. (2009). Chimpanzee tourism in relation to the viewing regulations at the Mahale Mountains National Park, Tanzania. Primate Conservation, 24, pp. 85-90


OFI. (2003). A message from Dr Birute Galdikas. Orangutan Foundation International


Redmond, I. (2008). The primate family tree. Firefly Books Ltd, UK


Roe, D., Leader-Williams, N. & Dalal-Clayton, B. (1997). Take only photographs, leave only footprints: the environmental impacts of wildlife tourism. IIED Wildlife & Development Series, No. 10


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


Singleton, I., Wich, S., Husson, S., Stephens, S., Utami Atmoko, S., Leighton, M., Rosen, N., Traylor-Holzer, K., Lacy, R. & Byers, O. (2004). Orangutan population and habitat viability assessment: Final report. IUCN/SSC Conservation Breeding Specialist Group, Apple Valley, MN


Snaith, T. (1999). The behaviour of free-ranging ex-captive orangutans in Tanjung Puting National Park, Indonesia. MA thesis, University of Calgary


Spenceley, A., Habyalimana, S., Tusabe, R. & Mariza, D. (2010). Benefits to the poor from gorilla tourism in Rwanda. Development Southern Africa, Vol. 27, No. 5


Thierry, B. (2007). The macaques: A double layered social organisation. In Campbell, C.J., Fuentes, A., Mackinnon, K.C., Panger, M. & Bearder S.K. Primates in Perspective. Oxford University Press


Wallis, J. & Lee, D.R. (1999). Primate conservation: The prevention of disease transmission. International Journal of Primatology, Vol. 20, No. 6


Westin, J.L. (2007). Effects of tourism on the behaviour and health of red howler monkeys (Alouatta seniculus) in Suriname. PhD dissertation, University of Michigan


Wilkie, D.S. & Carpenter, J.F. (1999). Can nature tourism help finance protected areas in the Congo basin?. Oryx, Vol. 33, No. 4, pp. 332-338


Yeager, C.P. (1997). Orangutan rehabilitation in Tanjung Puting National Park, Indonesia. Conservation Biology, Vol. 11, No. 3, pp. 802-805