The Sumatran rhinoceros, also known as the hairy rhinoceros or Asian two-horned rhinoceros (Dicerorhinus sumatrensis), is a rare member of the family Rhinocerotidae and one of five extant species of rhinoceros. It is the only extant species of the genus Dicerorhinus. It is the smallest rhinoceros, although it is still a large mammal, it stands 112-145 cm high at the shoulder, with a head-and-body length of 2.36-3.18 m and a tail of 35-70 cm. The weight is reported to range from 500 to 1,000 kg, averaging 700-800 kg, although there is a single record of a 2,000 kg specimen. Like both African species, it has two horns, the larger is the nasal horn, typically 15-25 cm, while the other horn is typically a stub. A coat of reddish-brown hair covers most of the Sumatran rhino's body. The males have larger horns than the females, though the species is not otherwise sexually dimorphic.
The rhino has a patch of long hair around its ears and a thick clump of hair at the end of its tail. Like all rhinos, they have very poor vision. The Sumatran rhinoceros is fast and agile, it climbs mountains easily and comfortably traverses steep slopes and riverbanks.
Members of the species once inhabited rainforests, swamps, and cloud forests in India, Bhutan, Bangladesh, Myanmar, Laos, Thailand, Malaysia, Indonesia, and China. In historical times, they lived in southwest China, particularly in Sichuan. They are now critically endangered, with only five substantial populations in the wild, four in Sumatra and one in Borneo. Their numbers are difficult to determine because they are solitary animals that are widely scattered across their range, but they are estimated to number fewer than 80. The species was completely extirpated from Malaysia in 2019, and one of the Sumatran populations may already be extinct. Sumatran rhinos compete with the Javan rhino for the unenviable title of most threatened rhino species. While surviving in possibly greater numbers than the Javan rhino, Sumatran rhinos are more threatened due to habitat loss and fragmentation.
Sumatran rhinoceroses were once quite numerous throughout Southeast Asia. Fewer than 100 individuals are now estimated to remain. The species is classed as critically endangered (primarily due to illegal poaching) while the last survey in 2008 estimated that around 250 individuals survived. From the early 1990s, the population decline was estimated at more than 50% per decade, and the small, scattered populations now face high risks of inbreeding depression. Most remaining habitat is in relatively inaccessible mountainous areas of Indonesia.
The poaching of Sumatran rhinoceroses is a cause for concern, due to the high market price of its horn. This species has been overhunted for many centuries, leading to the current greatly reduced and still declining - population. The rhinos are difficult to observe and hunt directly, so poachers make use of spear traps and pit traps.
In the 1970s, uses of the rhinoceros' body parts among the local people of Sumatra were documented, such as the use of rhino horns in amulets and a folk belief that the horns offer some protection against poison. Dried rhinoceros meat was used as medicine for diarrhea, leprosy, and tuberculosis. "Rhino oil", a concoction made from leaving a rhino's skull in coconut oil for several weeks, may be used to treat skin diseases. The extent of use and belief in these practices is not known. Rhinoceros horn was once believed to be widely used as an aphrodisiac; in fact, traditional Chinese medicine never used it for this purpose. Nevertheless, hunting in this species has primarily been driven by a demand for rhino horns with unproven medicinal properties.
The rainforests of Indonesia and Malaysia, which the Sumatran rhino inhabits, are also targets for legal and illegal logging because of the desirability of their hardwoods. Enforcement of illegal logging laws is difficult because humans live within or near many of the same forests as the rhino. The 2004 Indian Ocean earthquake has been used to justify new logging. Although the hardwoods in the rainforests of the Sumatran rhino are destined for international markets and not widely used in domestic construction, the number of logging permits for these woods has increased dramatically because of the tsunami. However, while this species has been suggested to be highly sensitive to habitat disturbance, apparently it is of little importance compared to hunting, as it can withstand more or less any forest condition. Nevertheless, the main cause of drastic reduction of the species is likely caused by the Allee effect. There are a variety of mechanisms that can create Allee effects, including mating systems, predation, environmental modification, and social interactions among others.
#Wildlife #AlleeEffect #Rainforest
25 окт 2021
