With fewer than 100 Sumatran rhinos remaining in the world, the species is verging on the brink of extinction. It is this tragic news that led Cincinnati Zoo to announce that it is hoping to mate a pair of captive Sumatran rhino siblings (see news story, July 2013) in an attempt to improve the survival chances of the species.
So what is the situation for the Sumatran rhino, and how can captive breeding programmes play a role in the species’ survival? Let’s start with an overview of the current state of Sumatran rhinos across the world.
Situation in Sabah, Malaysia:
Malaysia has a handful of Sumatran rhino left:
- One old, almost certainly post-reproductive, blind female called Gelogob, who was captured in June 1994. Her exact age is unknown. She has alternated between being kept at the Sepilok Orangutan Rehabilitation Centre, then in Kota Kinabalu Zoo and in a captive facility in Tabin Wildlife Reserve
- One male, Kretam, known as Tam, who was captured in August 2008, when he was roughly 20 years old, so he is now approximately 25. There have been several attempts to collect and cryopreserve sperm from Tam (through electro-ejaculation), but to-date, no high quality samples have been obtained.
- One female named Puntung, who was airlifted from a solitary life on a hill range in the Tabin Wildlife Reserve on 25 December 2011, in a dramatic operation, as a mate for the male rhino Tam. Puntung suffers from snare wound that has removed part of one lower leg, so this may mean she is unable to bear the weight of a male for natural mating. Punting also has reproductive pathologies; she has problems with endometrial cysts in the lining of her womb that could hinder the sperm from reaching the ova as well as prevent the implantation of embryos on the uterine wall. This condition is possibly as a result of long periods in the wild without reproductive activity
In addition, camera-trap footage shows evidence of just one wild rhino (female) surviving in Danum Valley. There have been no signs of any other wild rhinos in the whole of Sabah. Conservation groups intend to capture this female and bring her into the captive facility along with Puntung and Tam, but there are difficulties in getting authorities’ permission to do so.
No rhinos are thought to survive in Peninsula Malaysia. There used to be a captive facility, Sungai Dusun Rhino Conservation Centre in Selangor; however captive breeding efforts ended abruptly in late 2003 when all five rhinos died over a span of 18 days from a protozoan infection. So the only examples of the Malaysian Sumatran rhino subspecies are in Sabah.
Situation in Indonesia:
There are five Sumatran rhino kept in captivity in a large enclosure in the Sumatran Rhino Sanctuary (SRS), Indonesia.
- Old female called Bina, who was captured in 1991 as part of a zoo capture programme. She is probably post-reproductive. Initially Bina was kept at Bogor Zoo in Indonesia and then was moved to the SRS once it opened in 1998
- Young female called Rosa, who was captured in 2005 after she started straying into human areas outside of Bukit Barisan Selatan National Park. Unfortunately Rosa is very human-focused and has resisted attempts at natural mating with Andalas (see below)
- Young female called Ratu was captured in 2005 after she wandered outside of Way Kambas National Park and efforts to drive her back into the Park failed. She is a proven breeder and mother of Andatu
- 12-year-old male called Andalas, who was born 2001 in Cincinnati Zoo (see below) to Ipuh and Emi and sent to SRS in 2007. He is a proven breeder and father of Andatu
- Male calf called Andatu, offspring of Andalas and Ratu, born June 2012 at the SRS. Andatu made history as the first Sumatran rhino born in captivity in Indonesia
Experts estimate that there are approximately 90 Sumatran rhino remaining in the wild in the island of Sumatra in Indonesia, spread between three parks: Way Kambas NP, Bukit Barisan Selatan NP, and Gunung Leuser ecosystem, but precise figures are not known.
Situation in the rest of the world:
There are just two animals, held in captivity in the USA, who have now been reunited at Cincinnati Zoo.
- Nine-year-old female called Suci, born to Ipuh and Emi
- Six-year-old male called Harapan, born to Ipuh and Emi
- So all three calves born in captivity (until last year when Andatu was born in Indonesia) were born at Cincinnati Zoo to the same parents, Ipuh (dad) and Emi (mum), who are now both dead
Between 1984 and 1996, 40 Sumatran rhinos were captured and translocated from their native habitats to zoos and reserves across the world in an attempt to breed the species. While hopes were initially high, and much research was conducted on the captive specimens, by the late 1990s, not a single rhino had been born in the programme, and most of its proponents agreed the programme had been a failure. Apart from the Sumatran rhinos at Cincinnati Zoo, and Bina at the Sumatran Rhino Sanctuary, all other zoo animals caught during the capture operations are now dead. This includes a male Torgamba who was at Port Lympne Wild Animal Park in the UK and then sent to the Sumatran Rhino Sanctuary in Indonesia, but died in 2011
In April 2013, the Sumatran Rhino Crisis Summit was held in Singapore bringing together rhino experts, scientists, government officials and representatives of non-governmental organizations from around the world. With only 100 Sumatran rhinos remaining, participants in the conference recommended that an Intensive Protection Zone (IPZ) be created within Way Kambas National Park, in Indonesia, which is the only area where rhino numbers are thought to be stable and growing, and then rotate the animals through the SRS (rather than expand it per se). This would mean that intensive management / captive breeding efforts are mixed with extensive management, i.e. protection and monitoring within the IPZ. This decision has yet to be ratified / agreed. The future survival of rhinos in Sabah, Malaysia is unlikely, unless politicians agree to an exchange of animals between countries.
Captive-breeding programmes for Sumatran rhinos are increasingly important for the future survival of the species. All Sumatran-rhino-holding organisations meet for an annual Global Management and Propagation Board meeting, when they discuss breeding options. The GMPB has agreed that the two Sumatran rhino subspecies Dicerorhinus sumatrensis sumatrensis and Dicerorhinus sumatrensis harrissoni should be treated as one species, rather than trying to manage breeding separately.
So the possibilities for future captive breeding of Sumatran rhinos are small, which is why Cincinnati Zoo has decided to breed the Sumatran rhino siblings, Suci and Harapan. There is a strong possibility that unless Suci (and Rosa) are mated soon, they may miss their “biological window” and become infertile. It is vital that they are mated, or they may develop reproductive problems, as seen in captive female Puntung in Indonesia.
There is no point in sending Suci to Sabah as Tam’s fertility is in question, and there is greater expertise in successful breeding at Cincinnati Zoo, which has successfully bred three calves. There is also no point in sending Suci to SRS, as the only potential mate there currently is Andalas (unless more male wild rhinos are captured), who is Suci’s older brother.
So the only option for now is to mate Suci with her younger brother Harapan, who was born at Cincinnati Zoo, then moved to White Oak Conservation Centre in Florida, then to Los Angeles Zoo, and then returned to Cincinnati Zoo in July 2013.
The inbreeding of such close relatives in captivity is a controversial subject and a decision that is not taken lightly. Scientists strive to avoid such situations, but such a step is needed when a population drops to extremely low levels. The ideal situation would be to bring more animals into captivity, so that there are more breeding permutations available; however the Indonesian Government is unwilling to do so at present time. The drastically low numbers of Sumatran rhino in the wild means that inbreeding between such close rhino relatives may already be happening in the wild, but it is difficult to know because the animals are so rare and the genetics studies that would give us definitive answers have not yet been done.
There are several examples of species whose populations have been brought back from the brink of extinction by captive-breeding programmes and intensive conservation efforts. For example, the Southern white rhino numbered approximately 50 individuals at the beginning of the 20th century, before being bred up to today’s figures of around 20,405 animals. There are now several generations of Southern white rhinos with no apparent birth defects, although there must have been a high degree of inter-relatedness.
Another reason for maintaining a captive population of Sumatran rhinos in the USA is to avoid having all the rhinos in one place where they are at risk of disease, poaching and / or natural disaster that could potentially wipe out the entire captive population in one go.
Artificial Insemination options and Assisted Reproduction Technologies are being pursued by Malaysian scientists, together with the Institute for Zoo and Wildlife in Germany. However, there has only been limited success with artificial insemination in white and Greater one-horned rhinos and so much less is known about Sumatran rhino biology / fertility / reproduction, that these techniques seem less likely to succeed in the near future than natural conception.
It is important to cryogenically preserve as much genetic material – oocytes and gametes etc. as possible, and Cincinnati Zoo with its CryoBioBank and the Frozen Zoo in San Diego Zoo are ideally positioned to manage this.
The future of the Sumatran rhino needs government action and international collaboration to secure the remaining wild populations, along with using the knowledge and skills gained through recent successful captive breeding programmes.
Press release from Cincinnati Zoo http://cincinnatizoo.org/blog/2013/07/21/sumatran-rhino-returns-to-the-cincinnati-zoo-in-the-face-of-crisis/
Photo credits Alain Compost, YABI / SRS, SRI, Steve Robbins