Ropiquet & Hassanin, 2005
The Nilgiri Tahr, Nilgiritragus hylocrius, known locally as the Nilgiri Ibex or simply Ibex, is an ungulate that is endemic to the Nilgiri Hills and the southern portion of the Western Ghats in the states of Tamil Nadu and Kerala in Southern India. It is the state animal of Tamil Nadu. Despite its local name, it is more closely related to the sheep of the Ovis genus than the Ibex and wild goats of the Capra genus.
In the Tamil Language it is called varaiaadu, the term being composed of two Tamil words, wurrai a precipice, and aadu, a goat. It is also the state animal of Tamil Nadu. The ancient word in classical Tamil was "varudai" (வருடை: Natrinai, 359; Ainkurunuru, 287; Pattinappalai, 139). It was previously named Capra warryato by Gray.
Its closest relatives are sheep (genus Ovis). Until 2005, it was placed with the Himalayan Tahr (Hemitragus jemlahicus) and the Arabian Tahr (Arabitragus jayakari) in the genus Hemitragus. However, it has recently been transferred to a new genus Nilgiritragus because it is genetically more similar to members of the genus Ovis than to other Tahrs.
The Nilgiri Tahrs are stocky goats with short, coarse fur and a bristly mane. Males are larger than the females, and have a darker color when mature. Both sexes have curved horns, which are larger in the males, reaching up to 40 centimetres (16 in) for males and 30 centimetres (12 in) for females. Adult males weigh 80 to 100 kilograms (180 to 220 lb) and stand about 100 centimetres (39 in) tall at the shoulder. Adult males develop a light grey area on their backs and are thus called "saddlebacks".
These Tahrs inhabit the open montane grassland habitat of the South Western Ghats montane rain forests ecoregion. At elevations from 1,200 to 2,600 metres (3,900 to 8,500 ft), the forests open into grasslands interspersed with pockets of stunted forests, locally known as sholas. These grassland habitats are surrounded by dense forests at the lower elevations. The Nilgiri tahrs formerly ranged over these grasslands in large herds, but hunting and poaching in the nineteenth century reduced their population to as few as 100 animals by the early 20th century. Since that time their populations have increased somewhat, and presently number about 2000 individuals. Their range extends over 400 kilometres (250 mi) from north to south, and Eravikulam National Park is home to the largest population. The other significant concentration is in the Nilgiri Hills, with smaller populations in the Anamalai Hills, Periyar National Park, Palni Hills and other pockets in the Western Ghats south of Eravikulam, almost to India's southern tip. A small populations of Tahr numbering around 200 are known to inhabit the Boothapandi, Azhakiyapandipuram, Velimalai, Kulasekaram and Kaliyal Ranges in the Kanyakumari district of Tamil Nadu  and another small herd of less than 30 animals is known to inhibit Ponmudi hills in Trivandrum district of Kerala 
Several studies have occurred about Nilgiri Tahr across the last three decades. But the best known and one of the earliest was the two and half year long research at Eravikulam National park in Kerala by Dr. Clifford G. Rice of Washington Department of Fish & Wildlife and his Indian associate M.C. Philip in the late Seventies. Dr. Rice, then a graduate student at the Texas A & M University and a fellow with the American Institute of Indian studies, conducted extensive studies and data collection on Tahr herds in Eravikulam. He spent months with the herd and habituated them to his constant presence. This helped him to extensively photograph the animals and color collar about 50 females. The focus of his study was Tahr behaviour, their social hierarchy and mating rituals.
Other notable studies on Tahr include research works by E.R.C Davidar, who conducted the first census of Tahr in India and papers published by noted Biologist George Schaller, an expert on field work techniques. Inspired by Davidar's work, Schaller visited Nilgiris and the duo collaborated for sometime. Schaller, in his book, 'The Stones of Silence', pays tribute to Davidar's efforts in saving the endangered Nilgiri Tahr.
- Alempath, M. & Rice, C. (2008). Nilgiritragus hylocrius. In: IUCN 2008. IUCN Red List of Threatened Species. Retrieved 5 April 2009. Database entry includes a brief justification of why this species is of endangered.
- Prater, S.H. 1948, 1971. The book of Indian Animals, Bombay Natural History Society and Oxford University Press, India. 324 pages. ISBN 0195621697.
- Hamilton, General Douglas (1892). Hamilton, Edward, ed. Records of sport in southern India chiefly on the Annamullay, Nielgherry and Pulney mountains, also including notes on Singapore, Java and Labuan, from journals written between 1844 and 1870. London: R. H. Porter. pp. Illustrated, photo. Frontis of the author. Numerous illustrations, some full page. 284 pages. Quarto. (ref=page 113). OCLC 4008435.
- Ropiquet, A. & Hassanin, A. 2005. Molecular evidence for the polyphyly of the genus Hemitragus (Mammalia, Bovidae). Molecular Phylogenetics and Evolution 36(1):154-168
- "Bonnet Macaque tops in wildlife survey in Kanyakumari district"
- "Squeezing Life out of Ponmudi"
- Rice, Clifford G. (1988). Reproductive biology of Nilgiri Tahr. Journal of Zoology, London, 214: 269-284 (pdf).
|Wikimedia Commons has media related to Nilgiritragus hylocrius.|
- ARKive - images and movies of the Nilgiri tahr (Hemitragus hylocrius)
- The Nilgiri Tahr Trust, Kerala, India
- Nilgiri Tahr Information Website