Nilgiri Biosphere Reserve, Biosphere reserve in South India.

The Nilgiri Biosphere Reserve is a protected area in South India covering parts of Tamil Nadu, Kerala, and Karnataka states, and including several national parks and wildlife sanctuaries within its boundaries. The landscape changes from dense rainforests at lower elevations to open grasslands on plateaus, with each zone hosting its own plant and animal species.

The protected zone was established in 1986 and became the first of its kind in the country to receive recognition from UNESCO. The initiative arose to secure a large continuous forest area in the Western Ghats and protect its wildlife.

The name Nilgiri comes from the Tamil word neelam (blue) and the Sanskrit giri (mountain), often linked to the bluish flowers of kurinji shrubs. Tribal groups native to the reserve include the Toda, Kota, Irula, Kurumba, Paniya, Adiyan, Edanadan Chettis, Allar and Malayan.

Several information centers are located near the main entrances and provide maps and guidance about trails and observation points. The best time to visit is between October and May when paths are dry and animal sightings are more common.

The reserve holds India's largest Asian elephant population, estimated at 5,750 animals in 2007. Herds range over 562–800 km2 and gather at perennial water sources in the dry season. Above 1,800 m, stunted evergreen shola patches are festooned with epiphytes, and giant honey bees (Apis dorsata) build nests in trees taller than 18 m.