Primate species on verge of extinction
Syofiardi Bachyul Jb, The Jakarta Post/Padang
The population of the four primate species endemic to Mentawai Islands, West Sumatra, has dropped drastically due to excessive logging in the area. They are the bilou or dwarf gibbon (Hylobates klosil), simakobu or pig-tailed monkey (Simias concolor), bokkoi or Mentawai macaque (Macaca pagencis) and joja or Mentawai monkey (Presbytis potenziani).
Based on data collected by the World Wide Fund for Nature (WWF) in 1980 on Siberut island -- one of the four largest islands and home to the four primates -- the total population of bilou was 36,000, joja 46,000, simakobu 19,000 and bokkoi 39,000.
However, over the period of 18 years, their population drastically dropped. Based on data recorded at the Biodiversity and Conservation Study Center (PSBK), Mathematics and Natural Sciences (FMIPA) department of the University of Indonesia in 1998, the bilou population stood at 8,300, joja 2,200, simakobu 1,600 and bokkoi 1,300.
There is no data on the population of the four primate species on the island since then. But, according to head of the Siberut National Park Bureau, Tri Prasetyo, the total population of the primates, which could be found only on the Mentawai Islands, had definitely dropped due to rampant logging by Natural Forest Concession (HPHA) and Timber Utilization (IPK) permit holders. "We plan to take inventories of the population of the primates endemic to Siberut Island next year," said Tri recently.
They live in forested areas on four of the bigger islands on the Mentawai Islands namely, Siberut, Sipora, Pagai Utara and Pagai Selatan islands.
However, large-scale forest exploitation by HPHA and IPK permit holders on the three other islands since 1969, has caused their habitat to shrink and their populations to drastically drop.
Based on research by DJ Whittaker from the Department of Anthropology at the New York City University this year, the population ratio of the four species of endemic primates in Sipora was only 4.48 per animal per square kilometer (sq km), while on Pagai Utara and Pagai Selatan the ratio was 6.8 per individual animal per sq km.
According to him, the barren forests on the three islands have had an immediate impact on the conservation of the arboreal primates.
It is estimated that there are no more than 100 animals of each species on each island and they too are on the verge of extinction because there is little protected forest left.
Siberut island which measures 403,000 hectares, is one of the islands in the Mentawai island chain still covered by vast natural forests where the four species live. However, forest exploitation is on the rise there due to the unrestrained issuance of HPHA and IPK permits by the local authorities.
The Andalas Madani Cooperatives (KAM), affiliated to the Andalas University in Padang, obtained a concession area of 49,650 hectares in 2001. The Ministry of Forestry is now processing the forest concession permit for PT Salaki Summa Sejahtera which is allotted 49,440 hectares.
Besides that, seven companies and cooperatives holding permits issued by the Mentawai regent are operating 6,700 hectares of the forest.
These areas border the Siberut National Park which measures 190,500 hectares.
"These logging activities will have an influence on the decline of the primate populations there due to the decreasing room for their movement," said Tri.
Tri was convinced that logging activities had caused a decrease in the population of the four endemic primate species. One of the causes was that they would be severely depressed, run off and then die. Moreover, they not only survive in the national park, but also in forest concession area which forms the whole ecosystem.
They are not only threatened by large scale logging but also by the Mentawai people's habit of hunting and eating the flesh of the bilou, joja, simakobu and bokkoi. However, they do this in a traditional way by using poisoned blow darts.
The four islands in Mentawai, including Siberut, are recorded as islands with the densest primate population in the world, followed by Taiwan with one primate species, Sulawesi with seven species, Sumatra with one species, Madagaskar with 19 species and Kalimantan with four primate species.