Habitat, population dynamics, and conservation of the Nilgiri tahr, Hemitragus hylocrius

Abstract

In Eravikulam National Park, India, Nilgiri tahr Hemitragus hylocrius frequent the fringes of the grass-covered plateau. The two main types of grassland utilised by tahr were dominated by Eulalia phaeothrix and Andropogon polyptichus. The total wild population of Nilgiri tahr is about 2200. Available evidence suggests that the three largest populations have remained approximately stable in recent years. Annual mortality at Eravikulam NP was estimated to be 44–52% for young, 31–37% for yearlings, and 17–24% for adults. Life expectancy at birth was estimated at 3–3·5 years. There was evidence for mortality incurred by predation, disease, accidents, injury during intraspecific combat, and thermal stress. Relevant to conservation are the short life expectancy of Nilgiri tahr; the need for comparable information on size and structure of all extant populations; and the effect of weather patterns on the temporal distribution of births and census results.