Kalimantan is the Indonesian part of the island of Borneo, the 3rd largest island in the world. The Indonesian part covers some 580.000 km2 (225.000 sq mi), the vast area is home to only 12 million people, so most of the provinces, especially the interior is very sparsely populated, and the vast rain forests here is some of the most bio-diverse areas in the world. The Borneo rainforest is 130 million years old, making it one of the oldest rainforests in the world and 70 million years older than the Amazon rainforest. Borneo is very rich in biodiversity compared to many other areas. There are about 15,000 species of flowering plants with 3,000 species of trees, 221 species of mammals and 420 species of birds. Subject to mass deforestation, the remaining Borneo rainforest is one of the only remaining natural habitat for the endangered Bornean Orangutan. It is also an important refuge for many endemic forest species, as the Asian Elephant, the Sumatran Rhinoceros, the Bornean Clouded Leopard, and the Dayak Fruit Bat.