| Citation |
van Strien, N.J., Manullang, B., Sectionov, Isnan, W., Khan, M.K.M, Sumardja, E., Ellis, S., Han, K.H., Boeadi, Payne, J. & Bradley Martin, E. 2008. Dicerorhinus sumatrensis . The IUCN Red List of Threatened Species 2008: e.T6553A12787457. https://dx.doi.org/10.2305/IUCN.UK.2008.RLTS.T6553A12787457.en. Downloaded on 04 February 2020. |
Description |
JUSTIFICATION
This species is listed as Critically Endangered due to very severe declines of greater than 80% over three generations (generation length estimated at 20 years); and because its population size is estimated to number fewer than 250 mature individuals and there is an expected continuing decline of at least 25% within one generation; and because its population size is estimated to number fewer than 250 mature individuals, with no subpopulation greater than 50 individuals, and it is experiencing a continuing decline.
RANGE DESCRIPTION
The Sumatran rhinoceros once occurred from the foothills of the Himalayas in Bhutan and north-eastern India, through southern China (Yunnan), Myanmar, Thailand, Cambodia, Lao PDR, Viet Nam and the Malay Peninsula, and onto the islands of Sumatra and Borneo in Indonesia (Foose et al., 1997; Grubb, 2005). The species precise historical range is indeterminate, as early accounts failed to distinguish rhinos to specific level, due to partial sympatry with the other two Asian rhino species (Rhinoceros sondaicus and Dicerorhinus sumatrensis).
The subspecies Dicerorhinus sumatrensis lasiotis formerly occurred in India, Bhutan, Bangladesh, and Myanmar (Nowak, 1999). The subspecies is extinct in the three former countries, but there is a possibility that populations remain in northern Myanmar.
The subspecies Dicerorhinus sumatrensis harrissoni formerly occurred throughout the island of Borneo. Currently, the species occurs only in Sabah (Malaysia), although a few individuals may still survive in Sarawak (Malaysia) and Kalimantan (Indonesia) (Meyaard, 1986).
Dicerorhinus sumatrensis sumatrensis formerly occurred in Thailand, Peninsular Malaysia, and Sumatra (Indonesia). Presently, the subspecies occurs only in parts of Sumatra and Peninsular Malaysia (Foose et al., 1997).
It occurs from sea level to over 2,500 m asl.
DESCRIPTION
The total population is estimated at fewer than 275 individuals, though probably more than 220. Until the early 1990s the numbers continued to decline at a rapid rate with estimated losses of 50% or more of the population per decade (Foose and van Strien 1997). Over the last decade the decrease has been halted or slowed in most of the larger populations because of better protection, but animals are still being lost in the small remnant populations.
The subspecies Dicerorhinus sumatrensis sumatrensis now occurs mainly on Sumatra, where there are 170 to 230 individuals. It has its largest populations remaining in Bukit Barisan Selata, Way Kambas, and Gunung Leuser National Park (Foose et al., 1997). There are about 60 to 80 animals in Gunung Leuser, about 60 to 80 Bukit Barisan Selatan, and 15-25 in Way Kambas, with some local reports of rhinos occurring outside of protected areas in Aceh Province (Sectionov and Waladi pers. comm.). There are also a few small, non-viable populations, including no more than a few individuals in Kerinci-Seblat National Park. Some populations are decreasing due to poaching, with very steep decreases in some areas (Sectionov and Waladi pers. comm.). Poaching has ceased in Bukit Barisan Selata and Way Kambas National Parks recently (Sectionov and Waladi pers. comm.). Populations in Peninsular Malaysia are now very small, but the species possibly survives in Taman Negara National Park and in Tamon Besor/Belum area. It probably no longer survives in Endau Rompin National Park (Malaysia).
The majority of the few remaining individuals of the subspecies Dicerorhinus sumatrensis harrissoni occur in Tabin National Park in Sabah (Malaysia), with some also in the Danum Valley (also in Sabah). The total population in Sabah is likely to be about 50 individuals (Han pers. comm.). A two year survey from 2000-2002 indicated 6 known individuals, 10 probable individuals, and an additional 35 possible (Van Strien, 2005).
The population status of the subspecies Dicerorhinus sumatrensis lasiotis is unknown, with the very slight possibility that a small number of individuals survive in the Lassai Tract in Myanmar.
There are over 20 animals in captivity, mostly in Indonesia and Malaysia, with a few in the United States.
HABITAT AND ECOLOGY
The species inhabits tropical rainforest and montane moss forest, and occasionally occurs at forest margins and in secondary forest (Nowak, 1999). The species occurs mainly in hilly areas nearby water sources, and exhibits seasonal movements, moving uphill in times of lowland flooding (van Strien, 1975). This shy species is dependent on salt licks, and occurs mostly in primary forest in protected areas, but wandering into secondary forests outside protected areas, especially in the dry season in search of water (Van Strien, 1975; Boeadi pers. comm.).
Males are primarily solitary, but can have overlapping territories with females, which are commonly found with offspring (Nowak, 1999). The home range size of females is probably no more than 500 ha, while males wonder over larger areas, with likely limited dispersal distance. The species is generally solitary, except for mating pairs and mothers with young (Nowak, 1999). Its life history characteristics are not well known, with longevity estimated at about 35-40 years, gestation length of approximately 15-16 months, and age at sexual maturity estimated at 6-7 years for females and 10 years for males (Nowak, 1999; IRF website (www.rhinos-irf.org), 2007).
Home range: Males up to 5,000 ha, females 1,000 -1,500 ha. Daily movements between feeding sites and wallows are probably only a few kilometers per day. Longer treks are made when males and females go to saltlicks (5-10 km) and by males exploring their large ranges. Dispersal appears to be mainly by sub-adult animals (4-7 years) old. In this period they may be found rather far from the home grounds. Adults are very traditional in the use of their ranges and will not move away unless severely disturbed. Water is never very far away in the habitats occupied by the Sumatran rhino.
THREATS
The two principal threats are poaching and reduced population viability. Hunting is primarily driven by the demand for the supposedly medicinal properties of rhino horns and other body parts, and many centuries of over-hunting has reduced this species to a tiny percentage of its former population and range. The species is now so reduced that there are very small numbers in each locality where it still survives. As a result, breeding activity is infrequent, successful births are uncommon in many populations, and there is a severe risk of inbreeding depression (J. Payne pers. comm.). The species is frequently stated to be sensitive to habitat disturbance (van Strien, 1986), but timber extraction is of little or no significance to the species, as it is robust enough to withstand more or less any forest condition (J. Payne pers. comm.).
USE AND TRADE
Over-hunting for its horn and other medicinal products has driven this formerly widespread species to the brink of extinction.
CONSERVATION ACTIONS
The species has been included on CITES Appendix I since 1975, and legally protected in all range states. An extensive international co-operative programme for the conservation of this species is being implemented with in situ activities being conducted in Indonesia and Malaysia. The primary objectives are to develop and deploy effective anti-poaching teams and to provide the co-ordination capacity to manage and sustain the programme. Rhino Protection Units (RPU) have been a force majeur in stopping poaching in Sumatra. Many organizations are involved with these units, including the Government of Indonesia (Sectionov and Waladi pers. comm.). The expansion and reinforcement of anti-poaching programmes is the top priority if this species is to survive.
There are also ongoing efforts to develop managed breeding centers for the species in Indonesia and Malaysia. There have been recent advances in captive breeding techniques for this species, including a successful births at the Cincinnati Zoo in 2001 and 2004 (Khan et al., 2004). One of these offspring was transferred back to a breeding center in Sumatra.
There is a need for further surveys in northern Myanmar to determine the status of any remaining populations. |
