Last June, at the end of the entrance road to Berkat Forest, Tuapeijat Village, Sipora Island, Mentawai Islands, West Sumatra, an orange heavy equipment was seen working. It was stacking logs that had just been removed from the forest. The sound of chainsaws cutting trees could also be heard wailing from the forest. Only in the late afternoon did activities in the forest stop.
Berkat Forest is known as the habitat of four endemic Mentawai primates on Sipora Island. The four endemic primates are bokoi (Macaca pagensis), joja pagai (Presbytis potenziani), bilou (Hylobates klossii), and simakobu (Simias concolor). All of these primates live in the forest in different trees.
The primate species on Sipora Island are similar to those on Pagai Island. In a recent study, primate taxonomists separated the joja on Pagai and Sipora Islands from the joja on Siberut Island, due to species differences. Likewise, bokoi on Siberut are different species from bokoi on Pagai Island.
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Morphological characteristics also distinguish these two primate species. The joja on Siberut tends to be dark in color on the front of its body, while the joja on Sipora and Pagai have a golden color on the chest. Macaca siberu has a tail that curls at the end, while Macaca pagensis has a straight tail.
Like the other three islands in the Mentawai Islands, Sipora Island also has a diversity of animal and plant life due to the unique geological history of the Mentawai Islands. It is estimated that 500,000 years ago the fauna and flora of the islands were preserved from dynamic evolutionary changes, as happened in other areas of the Sunda Shelf. 65 percent of the mammals are endemic. Besides the primates of the Berkat Forest, Sipora Island, also has the rare endemic flying squirrel (Lomys sipora) and the Mentawai owl (Otus mentawi), the only endemic bird in the Mentawai Islands.