Biligiriranga Hills

The Biligirirangana Hills or Biligirirangan Hills (as referred to in biology and geology) is a hill range situated in Chamarajanagar District in south-western Karnataka, at its border with Tamil Nadu (Erode District) in South India. The area is called Biligiri Ranganatha Swamy Temple Wildlife Sanctuary or simply BRT Wildlife Sanctuary. It is a protected reserve under the Wildlife Protection Act of 1972. Being close to the Eastern Ghats as well as the Western Ghats, the sanctuary has floral and faunal associations with both regions. The site was declared a tiger reserve in January 2011 by the Government of Karnataka, a few months after approval from India's National Tiger Conservation Authority.

The hills are located at the north-west of the Western Ghats and the westernmost edge of the Eastern Ghats. Thus this area supports a diverse flora and fauna in view of the various habitat types present. A wildlife sanctuary of 322.4 square kilometres (124.5 sq mi) was created around the temple on 27 June 1974, and enlarged to 539.52 square kilometres (208.31 sq mi) on 14 January 1987. The sanctuary derives its name Biligiri (white hill in Kannada) from the white rock face that constitutes the major hill crowned with the temple of Ranganathaswamy (Vishnu), a major deity in Hinduism, or from the white mist and the silver clouds that cover these hills for a greater part of the year. An annual festival of Vishnu, held in the month of April, draws pilgrims from far and wide. Once in two years, the Soliga Tribals present a 1-foot and 9 inches slipper, made of skin, to the deity in Biligiriranga Hills.

The hills are in the Yelandur, Kollegal and Chamarajanagar talukas of Chamarajanagar District of Karnataka. They are contiguous with hills in Sathyamangalam Wildlife Sanctuary in Erode District of Tamil Nadu to the south. By road, they are about 90 kilometres (56 mi) from Mysore and 160 kilometres (99 mi) from Bangalore. The road leading to the village on top of the hills may be approached either from Yelandur or Chamarajanagar. Kyathadevara Gudi or K Gudi is located close to BR Hills, where safari is conducted.

The BR hills are a starting point of the Eastern Ghats and contact the border of the Western Ghats, allowing animals to move between them and facilitating gene flow between populations of species in these areas. Thus, this sanctuary serves as an important biological bridge for the biota of the entire Deccan Plateau.

The BR hills along with the Male Mahadeshwara Hills (MM Hills) range form a distinctly unusual ridge running north–south amidst the plains of Bangalore (~900 m), Mysore (~800 m) and Krishnagiri(~450 m). The peaks of these lofty ranges rise as high as 1,800 metres (5,900 ft) (BR hills 1,400–1,800 metres (4,600–5,900 ft); MM Hills 1,000–1,200 metres (3,300–3,900 ft)). The highest hill is Kattari Betta, at 1800 metres. Various observations point to a possible biogeographic link between BR hills and Nilgiri ranges.

Biogeographically, the sanctuary is unique. It is located between 11° and 12° N and the ridges of the hills run in the north–south direction. It is a projection of the Western Ghats in a north-easterly direction and meets the splintered hills of the Eastern Ghats at 78° E. This unique extension / offshoot of Western Ghats constitutes a live bridge between the Eastern Ghats and Western Ghats with the sanctuary located almost in the middle of this bridge. Thus, the biota of BRT sanctuary can be expected to be predominantly of Western Ghats in nature with significant proportion of eastern elements as well.

The sanctuary, ~35 km long north–south and ~15 km wide east–west, is spread over an area of 540 km² with a wide variation in mean temperature (9 °C to 16 °C minimum and 20 °C to 38 °C maximum) and annual rainfall (600 mm at the base and 3000 mm at the top of the hills) The hill ranges, within the sanctuary raise as high as 1200 m above the basal plateau of 600 m and run north–south in two ridges. The wide range of climatic conditions along with the altitude variations within the small area of the sanctuary have translated it into a highly heterogeneous mosaic of habitats such that we find almost all major forest vegetation types – scrub, deciduous, riparian, evergreen, sholas and grasslands.

The forests harbour close to 800 species of plants from various families and shows a close affinity to the Western Ghats.