Abstract

The endemic and endangered primates of Western Ghats namely lion-tailed macaque (Macaca silenus) annd Nilgiri langur (Trachypithecus johnii) were studied in Silent Valley National Park and adjacent areas, for a period of three years from 1993. Fourteen lion-tailed macaque troops constituting 275 individuals were identified. Eight lion-tailed macaque troops having 147 individuals were found to inhabit east of Kunthipuzha river. The population west of Kunthipuzha river constituted six troops having 128 individuals: average adult males and 45 adult females; subadult males constituted 6, subadult femals, juveniles, infants and cradled infants constituted the immature class with 41. Adult male-female ratio was estimated as 1:5:6, during the study periodtwo lion-tailed macaque troops fissioned. Ninty two plant species were utilized by the lion-tailed macaque for food which included 62 trees, 10 lianas, eight shrubs, six species of mushroom, three species of lichens and three parasitic plants. Among the food species, Cullenia exarillata used both for seeds and flowers, was favoured the most. An average of 21 plant species were used for food every month. The average home range size of lion-tailed macaque in the rainforest habitats of Silent Valley was estimated as 2.41 square kilometre. Nilgiri langur was commonly seen in the entire stretch of evergreen forests inside the National Park and semi-evergreen and moist deciduous forest along the fringes. Eighty five Nilgiri langur troops were identified. Among the 85 troops, 69 were ranging well inside the boundaries of the National Park, of which, Sairandri and Puchappara sections hold the majority of population. The remaining 16 troops were located from adjacent forest areas mainly in the Attappady Reserved Forest. Seventy nine troops were confined only to the evergreen forests. Nilgiri langur troops residing in the evergreen forests of Nilikkal border areas occasionally foraged to the adjacent moist deciduous forests. Average troops size was estimated as 5.89. The adult male-female ratio was estimated to be 1:2. Eighty nine plant species, utilized as food by Nilgiri langur, included 72 trees, 7 shrubs, 7 lianas, one herb, one reed , a parasitic plant and mushroom species. Home range of Nilgiri langur was estimated as 0.47 square kilometre