September 22, 2015

BORA views on World Rhino Day 2015

Sumatran rhinos are indeed likely to become extinct … but stopping poaching without boosting birth rate will not save the species — Borneo Rhino Alliance

Ceratotherium simum (White rhino), Dicerus bicornis (Black Rhino), Rhinoceros unicornis (Indian rhino) and Dicerorhinus sumatrensis (Sumatran rhino) belong to the same family, just as humans, orang-utans, gorillas and chimpanzees belong to the same family but belong to different genera. We would not presume that the same techniques should be used to promote breeding in all four ape species. Or that what was true in 1980s is the same as in 2015. Or that what is true in Kenya (for example) is true in Malaysia (for example). So there is no reason to treat rhinos as one big homogeneous type of animal with the same issues globally. Each species is different. The Sumatran rhino is the most different of all: it is about to go extinct … not primarily as a result of poaching but primarily because there are not enough births … and this has been the main problem for many decades.

Certainly, we cannot discount poaching. But there is no point in putting most of our efforts into preventing poaching if we are not putting even greater efforts into making more Sumatran rhino babies. You would think that that is common sense.

There is a misconception that more data are needed on wild Sumatran rhinos in order to imagine the best way to save the species from extinction. It does not matter if there are 37 or 57 or 127 Sumatran rhinos remaining (except that, if there are indeed “more studies”, those who think there might be more than 100 Sumatran rhinos are surely in for a nasty surprise. Every effort to estimate Sumatran rhino numbers in the wild after 1980 has resulted in wildly optimistic over-estimates).

To those who wish to deploy camera traps and get faeces to analyse for DNA: “Doing that will not give us any data of use in deciding on policy”. For a solitary and extremely rare animal (in most places where cameras are set, there will be only 0, 1 or 2 rhinos) there is NO way to estimate numbers in the wild. And even if someone does produce an estimate, we have no way of knowing of those individuals are fully fertile or if they are involved in breeding.

The points to bear in mind are: the number of Sumatran rhinos left is getting close to zero; the number that are fertile adults ready to breed is almost zero; the species WILL go extinct if ways are not found and IMPLEMENTED to boost the birth rate above that we have seen since 1980. Those points apply to both wild Sumatran rhinos and to the nine in captive conditions.

The difference between the wild and captive rhinos, however, is profound: we have no idea at all of the actual numbers, fertility, relatedness or frequency of mating (if any) of any wild rhinos. But with the -existence of a single collaborative programme – every rhino in fenced, managed conditions – can contribute to the goal of producing more babies. Even rhinos that cannot breed naturally can contribute.

In Sabah, sperm and eggs have been harvested successfully from Sumatran rhinos that otherwise would have no hope of contributing to production of babies. We in BORA agree that in vitro fertilization is NOT the solution for saving almost any other species from extinction. In fact, it is irrelevant and not even part of the solution for almost all species. But the Sumatran rhino is different. Every possible method known to man has to be used to produce more baby rhinos. Successful in vitro fertilization leading to embryo production is not unknown to man.

Let’s do it.


Filepic of Tam being coaxed into a trap with leaves. He was found wandering in an oil palm plantation in Kretam, Sabah in 2008.

Filepic of Tam being coaxed into a trap with leaves. He was found wandering in an oil palm plantation in Kretam, Sabah in 2008

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Comment: What we now know; what we need to do next

A Sumatran rhino wallows in a mud bath at Tabin Wildlife Reserve



The phrase “doing the same thing again and again, and expecting a different result” applies egregiously to the Sumatran rhinoceros. It is clear that protecting wild populations has failed, and that natural breeding in captivity results in too few births to be a viable strategy.

Over the past thirty years, very many more Sumatran rhinos have died than have been born, both in the wild and equally so in captivity. There are two possible solutions. One is to accept that saving this species is now too difficult and expensive, and to abandon it to extinction. The other is to focus entirely on production of Sumatran rhino embryos in the laboratory. This can be done by intracellular sperm injection into oocytes, where one sperm is inserted into an oocyte (thereby saving the millions of sperm that are always wasted during classical artificial insemination), and the resulting embryo implanted into a female rhino. There are at least two male Sumatran rhinos in captivity that are known sperm producers (Tam in Tabin, and Andalas in Way Kambas). Indonesia has three fertile females Sumatran rhinos in managed facilities at Way Kambas, none of which are producing babies by natural breeding. All captive females, including Puntung and Iman in Tabin, can be treated with hormones to boost and regularize oocyte production.

In theory, several hundreds of Sumatran rhino oocytes could be produced annually from captive females. Any extra embryos that might be produced can either be frozen for future maturation, or attempts could be made to implant them into zoo rhinos of different species.

We need to pose several pressing questions: why are we not doing this now? Why are we wasting time counting wild rhinos and not making any clear decisions? Why are the rhino experts not advocating for this? Why are the big international conservation organizations not explicitly supporting this idea?

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A comment on ‘Sex and the Single Rhinoceros’ by Henry Nicholls

Borneo Sumatran rhino Puntung in her temporary enclosure in the Tabin forest.

By Junaidi Payne (executive director) & Abdul Hamid Ahmad (chairman) BORA, 10 June 2012

The fine article entitled Sex and the single rhinoceros by Henry Nicholls (Nature, Volume 485:566-569, 31 May 2012) provides just the sort of debate that is needed on the pros and cons of trying to save species that are on the brink of extinction. And too much of the debate that has occurred was printed (not spoken) in academic journals, far from and never seen by those working on the ground.

Read the article in Nature: International Weekly Journal of Science

The founders of WWF saw the need in 1961 : supporting a very small number of dedicated people to do whatever necessary to promote breeding amongst very small populations of animals where the death rate had become higher than the birth rate (i.e. the Allee effect), in situations where governments were unable or unwilling to act. The original WWF vision meant that (a) the passionate people have to be found and helped with money and freedom to act, and (b) usually, at least some animals would need to be removed from the wild.

From the ground, it seems that a few subsequent decades of conservation genetics and philosophy has almost put paid to that sort of thinking. The classic cases of bisons and African rhinos at end of the 19th century, and those of the Arabian oryx and Hawaiian goose in the mid-20th century are barely mentioned nowadays. Government agencies and non-governmental organisations (NGOs) can get together for meetings to defer difficult decisions. Decades of time and money are wasted. The inevitable happens. The species goes extinct, but (usually) no-one can prove when the last animal dies, so no announcement is made. No-one need take responsibility for wrong decisions or failure.

We all know that habitats are being lost and will be lost, and that removing the factors causing species to become extinct need to be addressed. Those universal issues are not the ones that need to be addressed in the case of species like the Sumatran rhino, for which such concerns are too generic to be of use.

We still see statements that the Sumatran rhino is endangered by habitat loss, forest fragmentation and poaching. That is not true. The Sumatran rhino is endangered because there are hardly any of these rhinos left alive; many, probably most, remaining rhinos are infertile or too old to breed; fertile rhinos are so sparsely distributed that they no longer even meet; and at any one location, there is almost certainly inbreeding and skewed sex ratio. Those are the challenges to be either addressed or regarded as too difficult to tackle.

The question before us, therefore, is : If there are committed individuals and organisations that feel compelled to do what they can to save the Sumatran rhino from extinction, should they be encouraged to try, or to give up?

Only four elements are required to launch and sustain a programme to try to save a species on the brink of extinction. Firstly, there has to be a small group of dedicated people who get together, putting aside their egos, and decide to do whatever it takes. They have to formulate themselves as an NGO, in order to provide a legal entity with which governments and donors can interact. For the Sumatran rhinoceros, this has already happened in Malaysia (Borneo Rhino Alliance, BORA) and Indonesia (Yayasan Badak Indonesia, YABI). Secondly, one or a few big funders have to be secured, so the small group of dedicated people can work on the animal and human issues, and do not have to spend half their time worrying about how to raise funds. In the case of Malaysia, this role has been taken up by Sime Darby Foundation. In Indonesia, most funds for Sumatran rhinos are raised outside Indonesia via a US based NGO. Thirdly, the relevant government(s) have to provide support for the small group of people. That support can best be given just in terms of removing obstacles, and it has to be consistently whole-hearted from all parts of government that have some involvement in the programme. Fourthly, the local NGO and government need to obtain the best possible additional technical help that exists anywhere in the world and that might make a difference to the outcome of the programme. In the case of Sumatran rhino in Malaysia, the current big external help is from Leibniz Institute for Zoo and Wildlife Research, and this element of the rhino programme in Sabah (a State in the federation of Malaysia) was the one high-lighted in Nicholls’ article.

Once those elements are in place, there is no need for more stakeholder consultation or detailed action plans. When just a few animals are left, challenges and opportunities change by the month. Half the work is seat of pants.

Responding to the concern that there needs to be a long-term strategy for reversing the environmental pressures that are killing them off, and that captive breeding alone can never restore the wild population, we would argue that this is a matter of personal philosophy. When we first conducted surveys for rhinos in Sabah (J Payne in the early 1980s, Abdul Hamid in the early 1990s), the species was already critically endangered, and we estimated a total of about thirty rhinos in existence in Sabah at that time. The single major reason that accounts for the very small size of the remaining rhino population was a history of hunting for the horns, used in traditional Chinese medicine, over the past thousand years or so. By 1984, Government of Sabah had already agreed to the establishment of Tabin Wildlife Reserve (1,200 sq km) and Danum Valley Conservation Area (430 sq km), both previously unprotected forests that held the last remaining breeding rhinos. Since then, rhino numbers have declined still further. There have been hardly any signs of breeding, while targeted rhino poaching has been minor. As biologists, one can question whether the Sumatran rhino is well-adapted to closed canopy evergreen rainforest. Possibly it is a remnant taxon from the Pleistocene. (We do not want to enter here the debate as to whether, if that is true, there is ethical justification for trying to save a species that “should” be allowed to go extinct.) A combination of decreasing quality of the Sumatran rhino diet (mature leaves of woody plants – the lowest quality diet of any mammal species in South-east Asia) in the forest after the end of the Pleistocene and increasing temperature has forced this animal to evolve to a body size that is about as small as is possible for a rhinoceros. We can imagine that Sumatran rhinos are barely able to obtain enough nutrition to produce milk and foetuses and bear young from the sparse, fibrous leaves available in the under-storey of closed canopy forests. A combination of lower temperatures, fertile soils and extensive successional stage forests that might be needed to build up and sustain wild Sumatran rhino populations ceased to exist hundreds of years ago and may never exist again.

For the reasons outlined above, plus our fear that there may be even fewer rhinos left than the official figures, plus the likelihood that most are infertile or too old to breed, we no longer believe that the Sumatran rhino will survive in the wild, even with the complete cessation of poaching. We do not say this lightly. We have spent over 25,000 hours living inside tropical rainforests in Malaysia and Indonesia, conducting wildlife and vegetation surveys, starting in 1975, and arguing for the establishment of more rainforest conservation areas. Nicholls alludes to the disastrous 1984-94 period when 40 Sumatran rhinos were captured from forests then being converted to plantations, for a global captive breeding programme, based on an IUCN-brokered agreement. There are many factors which led to only one pair of those rhinos (in Cincinnati Zoo) breeding and producing three offspring, but the over-riding major one was inadequate genuine collaboration between the many players.

The triage argumentation for choosing species to be saved is of impeccable logic and replete with common sense. But decisions made in one part of the world cannot necessarily be implemented by decree in other countries. The success or failure of a programme to try to prevent the extinction of a species will depend on the particular circumstances in the country concerned, especially the motivations and stamina of the people involved during the critical two or three decades when intense sustained effort will be needed. If the response then is “we have factored that point into the triage decision on Sumatran rhinoceros”, our response is “the potential for success still boils down to the specific place, time and availability of willing people where the animal occurs.”

Regarding the question “should the money spent on trying to save a seriously endangered species be spent instead on another, more promising conservation project?” The answer is “no” because the question is predicated on an over-simplification of how money flows and is spent. The amounts spent on any conservation project are absolutely miniscule when compared to the daily flow of money around the world, the income of governments, and the wealth of the richest people anywhere in the world, including the wealthiest in Malaysia and Indonesia. One cannot argue that there is a small pot of money for which different conservation organisations compete – except in the narrow context of many NGOs applying for the same money from a few well-known conservation funds. Apart from the necessary commitments of governments for social welfare spending, whether one can obtain money for a particular venture from any potential source – whether aimed at profit-making or not – depends on a combination the people involved, marketing of the project, and luck.

Regarding the US$250,000 spent on the capture of the rhino Puntung. This is indeed our best estimate, given that it is difficult to separate all the costs that were directly linked to the capture from those linked to looking after two other rhinos already in captivity, and to running an NGO. Costs can normally be reduced significantly if obstacles beyond the control of the donor and NGO can be removed. The biggest part of that amount was sustaining half the full complement of staff over twenty months from placement of the first trap until removal of the rhino from the sixth trap, just two days after the trap had been completed.

We want to say something on the main corporate contributor to Sumatran rhino conservation in Sabah, and put that in the context of the article’s statements on Sime Darby as well as those of commentators on the article. Firstly, the Sumatran rhino was already endangered long before the expansion of oil palm plantations. We have said this many times to many people but there is a recurring tendency to attribute all endangered wildlife problems to recent forest loss, and forest loss in Malaysia and Indonesia to oil palm. Secondly, the spread of oil palm has occurred because oil palm yields the most profit per hectare per year on lowland soils in Malaysia and Indonesia when compared to any other land use outside urban centres. Malaysia (and Indonesia) are now in the last stages of the “land race” period in history, when the once widespread natural forests have been logged out or gone, and corporations, governments and poor people alike want to secure rights over specific land areas. Primarily, they want to secure the land for profit-making or speculation or subsistence. If crops other than oil palm yielded greater profits per hectare per year, then most land owners and claimants would switch to that other crop. But for the time being there is no such crop.

One of the most ground-breaking ventures relating to both oil palm and nature conservation is the formation of the Roundtable on Sustainable Palm Oil (RSPO;, a global not-for-profit association that includes stakeholders from seven sectors of the palm oil industry. RSPO is a voluntary, market-driven venture, currently with over 700 members globally, with a vision to “transform markets to make sustainable palm oil the norm.” Sime Darby, Malaysia’s largest palm oil producer, has to date produced about 30% of the global total amount of palm oil independently certified as sustainable according to the principles and criteria of RSPO. Sime Darby Foundation, operated independently of the palm oil producing arm of the company, has emerged over the past two years as one of the major financiers of wildlife projects in Malaysia, including the “Borneo Rhino Sanctuary” programme in Sabah. This mechanism of providing funds for conservation programme has merit over extra taxation by government, not least because of governmental inefficiencies and the fact that any extra tax might not necessarily go towards priority conservation programmes, and because palm oil producers feel that they are already over-taxed. Allocation of funds by Sime Darby Foundation is made on a competitive basis. The recipient of the funds (in the case of BORA, a not-for-profit company) is audited both by the donor and an audit firm.

We want to re-iterate the theme that conservation programme success depends on the specific people involved in the specific programme, by paying tribute to the dream team that is BORA. Apart from ourselves (a biologist and conservation biology professor from the local university) BORA has on a full-time basis Malaysia’s most experienced wildlife veterinarian (and arguably the world’s most experienced Sumatran rhino vet); a Malaysian entrepreneur, fund-raiser and social activist who always has a non-scientist’s eye view of things; a French biologist resident in Sabah who has managed many projects involving and training people from rural communities; a dedicated workaholic administrator; and more than twenty Sabahan natives who perform many jobs, some tedious, for 25 days every month and far from home.

In final summary, collective commitment and agreement is needed not to stand idly by and instead to do all that is possible to facilitate recovery of the species.





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View video footage of rhino conservation activities

Watch highlights of a video feature on BORA’s activities to rescue Borneo’s Sumatran Rhinos from extinction. The video is in Bahasa Malaysia and is used with permission from RTM.

View more videos here

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Bringing Puntung to the Sanctuary

Click on the links below to see images from the successful operation to capture Puntung and transport her to her new home.

Puntung capture photos (1st Part)

Puntung capture photos (2nd Part)

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BORA and BRS call on new Permanent Secretary

Sabah Wildlife Department comes under the Sabah State Ministry of Tourism, Culture and Environment. In 2011, the Ministry welcomed a new Permanent Secretary, Datuk Michael Emban, who is also Chairman of the Borneo Rhino Sanctuary (BRS) programme steering committee. BORA made a courtesy call on Datuk Michael on 23 May 2011 with Sabah Wildlife Department Assistant Director Dr Sen Nathan to outline progress of the BRS programme.

Picture shows Datuk Michael Emban (third from left) receiving a memento from Professor Dr Abdul Hamid Ahmad (left), Chairman of the BORA board of directors during the courtesy call. Also in the picture are Dr Sen Nathan (second from left), BORA Executive Director Datuk Dr Junaidi Payne (fourth from left), Deputy Permanent Secretary Mr William Baya,  and Assistant Secretary (Environment) Mr Edip Abun.

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Extinction of Vietnam rhinoceros and implications for Malaysia

The recent news of the extinction of the Javan rhinoceros on mainland Asia, with the death by poaching of the last remaining female in Vietnam in 2010, prompts us to draw attention to two implications for Malaysia. Firstly, this same kind of rhino went extinct in Malaysia in the 1930s. Thus, what seems at first to be only a local loss from Peninsular Malaysia has transformed into a global extinction of a unique population of Javan rhinoceros. It is now up to Indonesia to save the last remaining population of the species, on the island of Java. Secondly, there is another species of Asian rhinoceros of concern nearer to home. This is also an extremely endangered species, commonly known as the Sumatran rhinoceros, previously widespread in Asia but now confirmed to occur only in Indonesia and Malaysia.

Despite dedicated efforts to protect this species from poaching over the past few decades, within protected areas in Sumatra, Peninsular Malaysia and Sabah, numbers have continued to decline. Most specialists close to the situation now believe that habitat loss and poaching no longer represent the major threats to the survival of this rhino. Instead, numbers are so very low that factors associated with low numbers, including inability to find a fertile mate, pathology of the reproductive organs in females resulting in no pregnancies, inbreeding and skewed sex ratio, mean that for many years, rhino death rate has been exceeding birth rate. If this is so, then protection of the remaining wild rhinos and their habitat are necessary but insufficient measures to prevent the species extinction.


In a paper titled “Now or never: what will it take to save the Sumatran rhinoceros Dicerorhinus sumatrensis from extinction?” published in the international conservation journal Oryx earlier in 2011, Ahmad Zafir and his colleagues in WWF-Malaysia, Sabah Wildlife Department and Yayasan Badak Indonesia, wrote the following: “Recent data from governments, NGOs and researchers indicate that the global Sumatran rhino population could be as low as 216, a decline from about 320 estimated in 1995. Based on lessons learnt and expert opinions we call on decision makers involved in Sumatran rhino conservation to focus on a two-pronged approach for conservation of the species: (1) the translocation of wild rhinos from existing small, isolated or threatened forest patches into semi-in situ captive breeding programmes, and (2) a concomitant enhancement of protection and monitoring capacities in priority areas that have established these breeding facilities or have recorded relatively high population estimates and track encounter rates. At least USD 1.2 million is required to implement this two-pronged strategy annually in four priority areas: Bukit Barisan Selatan and Way Kambas National Parks on Sumatra, and Danum Valley Conservation Area and Tabin Wildlife Reserve on Sabah.” The Borneo Rhino Sanctuary programme is already underway in Sabah, based on those two approaches, and implemented by Sabah Wildlife Department with assistance from other agencies including Institute for Zoo and Wildlife Research (Berlin), Yayasan Sime Darby, WWF-Malaysia and Borneo Rhino Alliance, a recently established Malaysian NGO dedicated to saving the rhinos in Sabah. A similar programme has been underway in Indonesia for more than a decade.


The extinction of the Vietnam rhino suggests that leaving rhinos in the wild to be poached or die of old age is no longer an adequate approach. Instead, the Indonesian and Malaysian approach for the Sumatran rhinoceros is most likely now the only way forward to prevent the extinction of this species. Why bother to save the species? The argument is ethical, not economic. Fossils show that something very similar to this form of rhino has existed for about 20 million years, and we may be only a decade or two away from its extinction if no active interventions are made. Now that we know the situation, we ought to try to prevent extinction before that opportunity is lost. Is it worth the money? Ahmad Zafir and colleagues put that question in context, noting in their paper that the annual cost of running the ongoing programmes in Sumatra and Sabah is equivalent to the amount paid at an auction in USA in 2010 for a 1939 edition of a Batman comic book.


We surely do not want Malaysia to have to announce in a couple of decades from now news similar to that from Vietnam last month. Let’s recognise that efforts to promote the survival of the Sumatran rhinoceros ought to be made a national conservation priority.



This joint statement is signed off by the following organisations:


Borneo Rhino Alliance (BORA)

Land Empowerment Animals People (LEAP)

Resources Stewardship Consultants Sdn. Bhd. (RESCU)

Malaysian Nature Society (MNS)

TRAFFIC Southeast Asia



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What will it take to save the Sumatran Rhino




Now or never: what will it take to save the Sumatran rhinoceros Dicerorhinus sumatrensis from extinction?


-Abdul Wahab Ahmad Zafir, Junaidi Payne, Azlan Mohamed, Ching Fong Lau, Dionysius Shankar Kumar Sharma, Raymond Alfred, Amirtharaj Christy Williams, Senthival Nathan, Widodos Ramono and Gopalasamy Reuben Clements.

Copyright notice: Cambridge University Press

Read the full article.


We’re sure many of you know that one of the world’s most magnificent and docile creatures, the Sumatran Rhinoceros (Dicerorhinus sumatrensis), is in deep trouble.

But just how bad is it? From a population of around 320 estimated in 1995, experts now say it could be down to as low as 216 individuals.

One of Rimba’s researchers, Reuben, was involved in a review published recently in the international journal Oryx. This paper was led by Ahmad Zafir Abdul Wahab (currently doing his PhD based at Universiti Sains Malaysia; to find out what needs to be done to save this species from extinction. The consensus is that:

1) Wild individuals have to be captured and put in carefully managed forests that are as large and natural as possible.

2) There has to be an urgent injection of government and private funding to improve protection and monitoring capacities of agencies  working on rhino conservation in four priority areas: Bukit Barisan Selatan and Way Kambas National Parks in Sumatra, and Danum Valley Conservation Area and Tabin Wildlife Reserve in Sabah.

Once this basic level of funding is secured for these priority areas, more funds need to be channeled towards a search party to determine the status of rhinos in two other important areas, Gunung Leuser in Sumatra and Taman Negara in Peninsular Malaysia.

Just how much are we talking about for this basic level of funding? Only USD1.2 million! Pocket change for some people, especially the guy who bought a 1939 Batman comic for the same price at an auction in Dallas, back in February 2010.

Surely the price of the Sumatran rhino’s existence is worth much more than a comic book? Surely governments and noble companies can put together a fraction of their GDPs and annual revenues to save this species?

Although the Sumatran rhino has a negative SAFE index of -1.36 and is tipping over into the chasm of extinction, there have been positive historical examples of rebounding rhino populations:

In southern Africa, white rhinos (Ceratotherium simum) rebounded from just 20-50 individuals in the early 1900s to around 17,480 individuals today.

In India and Nepal, Indian rhinos (Rhinoceros unicornis) rebounded from only 200 individuals at the turn of the 20th century to around 2,575 individuals today.

Recovering from 216 individuals is by no means easy in this day and age, but history has shown it’s possible.

Please contact organizations actively engaged in Sumatran rhino conservation like the Borneo Rhino Alliance or International Rhino Foundation if you want to help preserve the existence of the Sumatran rhino. It’s now or never…

Full citation: Ahmad Zafir, A. W., Azlan, M., Lau, C. F., Sharma, D. S. K., Payne, J., Alfred, R., Williams, A. C., Nathan, S., Ramono, W. S., and Clements, R.G. 2011. Now or never: what will it take to save the Sumatran rhinoceros (Dicerorhinus sumatrensis) from extinction? ORYX 45: 225-233.



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Why are Sumatran rhinos so seriously endangered?

Current situation

The current number of living individuals of the Bornean subspecies of the Sumatran rhino (Dicerorhinus sumatrensis harrissoni; also known as the Bornean rhino) is possibly around forty or less. Sabah now offers the only likely prospect for saving this sub-species, and the best prospect for saving the species in Malaysia.

Based on morphological characters, Groves (1965) favoured separation of the Borneo form of the Asian two-horned or Sumatran rhinoceros (Dicerorhinus sumatrensis) as a distinct sub-species (D. r. harrissoni), with D. r. sumatrensis regarded as a single form occurring in Sumatra and Peninsula Malaysia. Based on mitochondrial DNA, however, Amato et al (1995) concluded that all Sumatran rhinos in Indonesia and Malaysia should be regarded as a single conservation unit. These results are of great significance : the Sumatran rhinoceros is now so highly endangered that mixing of Bornean and Sumatran forms in captive situations represents a potentially significant means to increase the number of births.

Historical context

The fact that the ecologically similar Javan rhino and Malay tapir became extinct in Borneo before the expansion of the human population suggests that natural factors may have played a role in the low population density of rhinos. Pressure from hunting of rhinos for their horns (a mainstay of ancient Chinese medicine) has likely been ongoing over long periods. The Bornean rhino was widely distributed in at least some localities in eastern and central Sabah in the late nineteenth century (Payne 1990), but the population was likely depleted below natural carrying capacity by that time. The species was already regarded as very rare and endangered in Sabah by 1961 (Burgess, 1961). Payne (1990) showed that isolated ones or twos of rhinos occurred in many parts of eastern Sabah as recently as the 1970s, but the species quickly became extinct at most sites during the 1980s. Davies and Payne (1982) noted that all Sabah rhino records compiled in 1981 showed that a natural salt source or mud volcano was present within a maximum of 14 km for all records, suggesting that the species distribution may be limited by access to certain minerals. More recently, it has been noted that all confirmed Sabah rhino records from late nineteenth century to present occur on sedimentary (most) and volcanic (some) derived soils, with none on crystalline basement and ultramafic rocks. Although overall rhino numbers have continued to decline in Sabah since 1980, the general pattern of rhino distribution (very small breeding populations in what are now Tabin Wildlife Reserve and Danum Valley Conservation Area, with a few scattered individuals elsewhere) has remained remarkably constant.

The argument that it is too late to save this rhino because of inbreeding is not valid. The African and Indian rhinos species were in a similar situation about a century ago, as were several other large mammal species such as the European bison, Arabian oryx and Pere David’s deer, all of which were built up to much larger numbers with appropriate passion and action by a small number of people.

Major threats faced by rhinoceros today

Very low numbers

The Sumatran rhino is one of the most endangered animal species anywhere in the world. Less than 40 rhinos are believed to survive in Sabah. Even if half are females, and some are too old or too young to reproduce, perhaps only six to seven remaining rhinos have the potential to give birth. With a birth interval of three years under optimum conditions, no more than two rhinos are being born annually (see below). The Allee effect (Allee, 1931) refers to a phenomenon whereby a positive correlation exists between of individual fitness (e.g. survival probability, fertility, reproductive rate) and population density of the species (Courchamp et al, 2008). As numbers of individuals of a species decline to a low very level, the various factors associated with very low numbers (e.g. narrow genetic base, locally skewed sex ratio, difficulty in finding a fertile mate, reproductive pathology associated with long non-reproductive periods; see below) conspire to drive numbers even lower, to the extent that death rate eventually exceeds birth rate, even with adequate habitat and zero poaching. In the absence of specific actions to bring Sumatran rhinos together and boost production of offspring, therefore, there is a strong possibility that the Sumatran rhino may go extinct even if protection of rhino habitats and rhinos can be maintained and improved.


Birth rate

The only information on inter-birth interval for the Sumatran rhino comes from Cincinati Zoo, where three young were born at intervals of 2 years and ten months between 2001 and 2007. For wild Sumatran rhinos, actual birth interval is likely to have been less in recent decades, because of the paucity of sites with fertile females and males present.

Cranbrook (2009) points to the long inter-birth interval of these taxa, and refers to Johnson’s (2006) modeling of different levels of off-take applied to large mammals, whereby a small increase in juvenile mortality can hold recruitment rates below a level needed to replace breeding adults. If Danum and Tabin are each assumed to contain 15 rhinos, and that about half are females, and that of those females some are too old or too young to reproduce, perhaps only three or four rhinos in each area will be reproductively active. With a birth interval of three years under optimum conditions, only one rhino will be born into each population annually – this would explain the apparent zero rate of population increase in these protected areas. Even this may now represent an optimistic scenario.

Reproductive tract pathology

At least half the female rhinos caught between 1984 and 1995 had reproductive tract pathology (Schaffer, 2001), a phenomenon associated with lack of breeding and carrying of fetuses to successful birth that appears to particularly afflict rhinos (Hermes et. al, 2006). The fact that at least some wild female Sumatran rhinos have exhibited this pathology at time of capture indicates that not all wild female rhinos are breeding, presumably due to insufficient fertile males to meet and mate.

Skewed sex ratio

A period of active capture of rhinos from sites in Sumatra in 1959, and from Sumatra, Peninsula Malaysia and Sabah where forest was being converted to plantations between 1984 and 1995 and Sabah revealed differences in sex ratio. Of nine rhinos caught in the Siak River area, Riau, Sumatra, in 1959, only one was a male (Skafte, 1964). At that time, Riau was largely forest-covered. Of twenty rhinos caught at various locations in Sumatra between 1985 and 1992, a period of accelerating forest loss, eleven were females. Later, in September 2005, two immature female rhinos were caught (named Rosa and Ratu), each having apparently moved into inhabited semi-forest areas from Bukit Barisan Selatan and Way Kambas National Park respectively. Of twelve rhinos caught in Peninsular Malaysia between 1984 and 1994 from several separate regions, nine were females. Since female Sumatran rhinos are believed to have smaller home ranges than males, and siting of rhino traps was based on well-used rhino paths, and the sample size is small, this bias towards females is not unexpected. Yet a severe bias in sex ratio in the opposite direction was observed in Sabah where, between March 1987 and November 1995, a total of ten rhinos were captured. Of those, nine were caught within an area of about 120,000 hectares which would up to around 1980 have been contiguous forest cover. Of the nine, one was a mature female and eight were mature males. Although the sample size is small by normal standards in biology, there are unlikely to have been many, if any, rhinos not located during the conversion of 120,000 ha of forest. Thus, the remnant rhinos in this small population were almost all mature males. The tenth rhino, caught in April 1989, was a young female (named Lun Parai) that had arrived near a major road and which may have come from Tabin Wildlife Reserve, the nearest large block of forest some 25 km away in a straight line. Not much can be gleaned from these records and a similar situation will not happen again, as there is now much less forest and much fewer rhinos. It is clear, however, that a biased sex ration may occur in very small populations of Sumatran rhino. The observations from Sabah also suggest that female rhinos, potentially easier to locate than males because of their presumed use of smaller areas, had already been selectively taken by hunters before the start of government-sponsored trapping for a captive breeding programme. Also, despite the very small sample size, the three cases of young rhinos moving out of forest into areas inhabited by humans suggests that young adult rhinos may tend to move far from their natal area.

Hunting and trapping

At any time, a single rhino poaching or inadvertent trapping event may represent the tipping point that pushes the species to a trajectory of extinction in Sabah.

Cause for optimism

The rhino in Sabah represents one of the few examples of a tropical large mammal where forest loss is not a major issue threatening the species. Conservation efforts can focus, therefore, exclusively on minimizing human-induced mortality and on bringing fertile females and males together.


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Borneo’s hairy rhino

A moment to treasure - a female Sumatran rhino and her young.

Together with the Javan Rhino, the Sumatran Rhino (Dicerorhinus sumatrensis) is the most critically endangered of the rhino species. This rhino species may represent the rainforest relic of a rhino which was once adapted to the open woodlands of the Pleistocene ice ages when sea levels were much lower than now, and Borneo and Sumatra were joined to mainland Asia via savannahs now under the South China Sea.

Over the past millennium, hunting and habitat loss have driven this rhino to the brink of extinction. Now, there may be just too few fertile females and males in any one forest area to sustain breeding.

Scientists now estimate that there are only about 200 animals remaining in the wild, clinging to existence in highly fragmented populations. As the persistence of populations in Peninsular Malaysia is very much in doubt, Indonesia and Sabah hold the only significant breeding populations. Between 30 – 40 rhinos are thought to be found in Sabah’s Tabin Wildlife Reserve, Danum Valley Conservation Area, and pockets of eastern and central Sabah.

In Indonesia, small populations may be found in three Indonesian National Parks in Sumatra: Bukit Barisan Selatan, Way Kambas and possibly Gunung Leuser.

Sumatran rhinos can be expected to persist and breed only in protected areas where they are physically guarded from harm by Rhino Protection Units. The continuation of this protection provides a necessary but perhaps insufficient means for the species’ survival. Active programmes to bring fertile females and males together may now be a necessary supplement to pull the species back from the brink of extinction.

The Littlest rhino

The Sumatran Rhino found in Sabah, is somewhat smaller than that found in Sumatra. It ranges from 4 to 5 feet in height, and 6.5 to 9.5 feet in length. Of course little is relative when discussing rhinos! Sumatran rhinos still weigh in at between 500 and 800 kilos. The Borneo form has been classified as a sub-species belonging to the same species as the rhinos found in Sumatra. This is based on skull shape, DNA and a slight difference in size – the Sumatran rhinoceros is now known as Dicerorhinus sumatrensis sumatrensis while the Bornean rhinoceros is more correctly referred to as Dicerorhinus sumatrensis harrissoni.

The Sumatran Rhino is also known as the Asian Two-horned rhino because of its two horns – a larger anterior horn and a smaller horn behind it. However, the main feature that distinguishes it from the other four rhino species is its covering of hair and reddish-brown skin. This is why the Sumatran rhino is sometimes called the ‘hairy rhino’.

Sumatran rhinos are browsers and consume a wide variety of plant species in the tropical forest. They have a lifespan of between 25 and 35 years. Mothers give birth to one calf every 3 years and the gestation period for a Sumatran rhino is 15-16 months. Females reach sexual maturity between 6 and 7 years of age, while males mature at approximately 8 years of age. Sumatran rhinos are generally solitary in nature and generally form temporary associations for mating before parting ways once again.

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