Established in the year 1986, Nilgiri Biosphere Reserve is the first biosphere reserve in India. It is located in the Western Ghats between 76°- 77° 15'E and 11° 15' - 12° 15'N. Primary objectives in the establishment of this reserve include conservation of the in-situ genetic diversity of species, restoration of degraded ecosystems to their natural conditions, providing data for ecological and environmental research and education and functioning as an alternative model for sustainable development.
The total area of the Nilgiri Biosphere Reserve is 5,520 sq km. It encompasses parts of Tamil Nadu, Kerala and Karnataka. The annual rainfall of the reserve ranges from 500 mm to 7000 mm with temperature ranging from 0°C during winter to 41°C during summer. The Nilgiri Biosphere Reserve comes under the biogeographic region of the Malabar rain forest. The Mudumalai Wildlife Sanctuary, Wyanad Wildlife Sanctuary, Bandipur National Park, Nagarhole National Park, Mukkurthi National Park and Silent Valley National Park are the protected areas in this reserve. Rich in plant diversity, about 3,300 species of flowering plants can be seen here. The fauna of the Nilgiri Biosphere Reserve includes over 100 species of mammals, 350 species of birds, 80 species of reptiles and amphibians, 300 species of butterflies and innumerable invertebrates. Fishes, amphibians and reptiles endemic to the Western Ghats also occur in the Nilgiri Biosphere Reserve.
Many major tributaries of the river Cauvery have their sources and catchment areas within the reserve. Many hydroelectric power projects are functioning in the Kundah, Bhavani and Moyar basins.