OLL LEWIS: The State of the Sumatran Rhinoceros

Whilst there is still no news from Sumatra, Oll is hard at work looking at the forteana of that strange island...

Another of the fantastic and unusual creatures found in Sumatra is the critically endangered Sumatran rhinoceros (Dicerorhinus sumatrensis). The Sumatran rhinoceros is the only member of the genus Dicerorhinus and is also known as the hairy rhinoceros because of the long hair that covers its body. Because populations of the species have become geographically isolated over time, three distinct subspecies have evolved. These are the Western Sumatran rhinoceros (Dicerorhinus sumatrensis sumatrensis) found on the island of Sumatra itself and the Malaysian Peninsula, the Eastern Sumatran rhinoceros or Bornean rhinoceros (Dicerorhinus sumatrensis harrissoni) found only in the Tabin Wildlife Reserve in Borneo and the Northern Sumatran rhinoceros (Dicerorhinus sumatrensis lasiotis) once found in India and Bangledesh.

All subspecies are critically endangered as there are less than 300 individuals left in the wild, but the situation is especially bad for the Eastern Sumatran rhinoceros as they are now thought to be present in only one area of national park in Borneo and single sites like this can be easily wiped out by natural disasters and disease can have a devastating effect on them, potentially completely wiping out all individuals. There are thought to be only 50 surviving Eastern Sumatran rhinoceros so they are likely not to be very genetically diverse which would also have a serious impact on the sub-species’ susceptibility to disease both in terms of potential genetic immunity and in an increased likelihood of genetic abnormalities.

Things may be even worse than that for the Northern Sumatran rhinoceros, as it may be extinct already. The Northern Sumatran rhinoceros once ranged across India and Bangladesh but it is thought that not a single Northern Sumatran rhinoceros survives in these countries having been wiped out by habitat destruction, disease and poachers. Poachers target the rhinos because of the high price that the creature’s horn fetches on the black market for use in Chinese medicine which is particularly galling because the powdered rhino horn used in Chinese medicine as a fever treatment is chemically and structurally identical to ground up fingernail cuttings, are people who bite their fingernails any more healthy than the rest of us? Not the last time I checked! Although declared extinct it is thought possible that there may still be an extant population in Burma but scientists have not been able to verify this for many years because of the political situation that exists there. Sadly it is very likely that poachers would have taken advantage of the situation and there is very little chance this population survives to the present day.

The outlook for the Western Sumatran rhinoceros, although less bleak than that of the other sub-species, is still dire due to its low population. Conservationists are doing the best that they can with what they have to work with and the Western Sumatran rhinoceros is protected in five locations, four in national parks in Sumatra and one on the Malaysian peninsular. Due to the rarity of the species attempts were made in the 1980s and 90s to breed the species in captivity. In 1984 40 rhinos were taken from the wild and into zoos in an attempt to get them to breed. None did. The program was a complete and abject failure and the IUCN noted that the program had failed to even keep the animals within the acceptable limits of mortality with 20 of the rhinos being dead by the mid 90s. Further casualties arouse within the Sumatran Rhinoceros Conservation Centre in Malaysia in 2004 when an outbreak of surra killed all but eight of the captive rhinos there.

All but one of the survivors were sent to the USA and by 1997 the project had been all but abandoned and only three of the captive rhinos survived in zoos dotted across the USA. No doubt realising what a senseless waste it was to have the animals apart, the remaining three captive animals were reunited in Cincinnati Zoo for one last attempt to get them to breed. All attempts ended in failure, although one of the females became pregnant 5 times these were never carried full term, until 2001 when the zoo-keepers treated the pregnant rhino with hormones and the baby was carried to full term. This was the first successful captive birth of a Sumatran rhinoceros since the 19th century and the first of three successful births at the zoo to date. The first rhino calf has since been sent back to Sumatra to take part in breeding programs in the natural habitat there.

Captive breeding in zoos of Sumatran rhinos, even with Cincinnati’s success, is now considered to be a poor substitute for letting the animals breed in the wild in well protected habitats and reserves. However, because of the threats facing the Sumatran rainforests from legal and illegal logging and palm oil plantations it is certainly possible that captive breeding may have to form a part of future conservation programs.