The behavior and ecology of Nilgiri tahr (Hemitragus hylocrius Ogilby, 1838)

Abstract

The behavior and ecology of Nilgiri tahr was investigated during a two-year field study at Eravikulam National Park, Kerala, India. The primary method of investigation was direct observations on wild tahr. The Nilgiri tahr is one of three species of tahr comprising the genus Hemitragus in the subfamily Caprinae. The distribution and current status of Nilgiri tahr is reviewed. Nilgiri tahr assembled in mixed groups of all sizes up to 150. Males separated from mixed groups outside the rut, and were found in small groups (up to 20) or alone. While mixed groups primarily utilized the grassy plateau margins, males also ventured further onto the center of the plateau and onto shrubby areas below cliffs and slabs. The Nilgiri tahr populations whose history is known have remained stable, despite a variable reproductive rate. Mortality was estimated at about 40% for subadults, and 20% for adults. Nilgiri tahr give birth to one young. The main birth season is in January-February, although additional births took place during the monsoon. Observations indicated that leopard, Asiatic wild dog, and man were the main predators on the Eravikulam tahr population. Tiger and jackal, although present, did not seem to play a significant role in Nilgiri tahr life history. The social behavior of Nilgiri tahr is described, with emphasis on agonistic and sexual behavior. The role of these behaviors in the rutting season is discussed, and comparisons drawn with related species. Recommendations are presented for the maintenance of existing Nilgiri tahr populations, and it is suggested the reintroductions be attempted if suitable sites can be found and protected.