The Siberut island is characterized by a wet equatorial climate, with minimum and maximum temperatures of 22o C (71.6F) and 31o C (87.8F). The dry season is from February to June and the raining season is from July to January. Siberut is hilly with wide variations in elevation. Almost 60% is covered by tropical rain forest with many forest type such as: primary dipterocarp forest, primary mixed forest, swamp forest, barringtonia forest and mangrove forest. Also, there are many rivers on the islands with a complex system of tributaries.