The recent “rescue” of the young female Sumatran rhinoceros, Puntung, from the heart of the Tabin Wildlife Reserve in Borneo has raised much hope for the survival of the species which is in its twilight existence and nearing extinction.
There is no reliable method to estimate their numbers as these animals lead solitary lives in remote areas and are almost never seen. It is believed that less than 30 remain in Sabah and around 150 remain in Indonesia while there could be a few remaining rhinos scattered in other areas.
Only 10 Sumatran rhinos are currently in managed breeding programmes around the world. Besides Puntung, there are two other rhinos, Kertam and Gelogob who are also in the Borneo Rhinoceros Sanctuary (BRS), while there are four in Indonesia (Andalas, Ratu, Bina and Rosa), two at the Cincinnati Zoo (Ipuh and Suci) and Harapan is Los Angeles, USA.
The life span of the Sumatran rhinos, based on the few individuals in breeding facilities between 1990s to present, is up to about 35 years and their population is dwindling rapidly due to very few births in recent decades.
Unlike other animals which live in herds, this most ancient of living mammal types which has been facing intense hunting pressure over the past 1,000 years, especially for horns used in traditional Chinese medicine, could have resulted in them living solitary lives to survive and breed.
More rhinos are believed to have died in the past years compared to those born. This is because there are so few of them left in the wild thus reducing their chances of meeting and mating, and due to the few fertile rhinos in any area, breeding hardly occurs. Wild rhinos also only meet to mate and are solitary otherwise. Mating is possible only every 23-25 days and when the female is receptive and fertile. Most months, no male will find the potentially receptive female.
Since these rhinos are normally solitary, they tend to regard each other as a threat or interloper, whether they are males, or between male and female and hence, even their mating, when it happens is violent. When a female is ready to mate, she gives off a scent to attract the male and if the male tries to mate when she is not receptive, she may flee or fight back.
While natural mating is still the best choice, artificial insemination is an option to boost the pregnancy rate as there are only four fertile Sumatran rhinos currently in breeding facilities (one in Sabah, two in Sumatra, 1 in USA) as the rhinos become less fertile as they age.
Working in these rhinos to save them from extinction is actually a race against the clock as once the rhinos are pregnant, the gestation period is at least 15.5 months, with the new born rhino staying with the mother for at least four years.
Miscarriage rate is also believed to be high for this rhino as has been the case with at least two pregnancies in breeding facilities at the Cincinnati Zoo and at the Way Kambas Sanctuary in Indonesia.
It is also believed that conception could be difficult due to low sperm counts and even deformed sperm which have been discovered among the few male Sumatran rhinos in breeding facilities in the past 20 years. One of the theories which is being examined that this is due to the rhinos being a very ancient species, "on the way" to extinction. Another theory is that the rhinos have in some way been affected by pesticide usage which has not affected the breeding patterns of other animals such as elephants and macaque monkeys, which also feed from plantations.
Another speculative idea is that the rainforest plants on which rhinos feed contain natural compounds that might inhibit sperm production.
It is hoped that with global efforts towards preventing their extinction via the Sumatran Rhino Global Management and Propagation Board (GMPB) could bear fruit. Yayasan Sime Darby which has pledged RM11.4 million until 2015 towards the BRS joined the organisation last year.
The main aim of the GMPB is to recommend and decide on the management of the global Sumatran Rhino population as a truly global population to maximise the options for reproduction and to improve its vitality in a global Sumatran Rhino propagation programme.
The GMPB is also looking at preparing and facilitating exchange of animals between all locations if indicated for the purpose of the programe including sharing the experience and transfer of knowledge and technology.
The rhinos need real protection in their habitat but efforts must include biological monitoring and international support at a global level to protect and conserve them.
Hence, to save the Sumatran rhinos, a big step forward is needed as small steps won’t just work anymore.
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