Impact of biotic disturbances on nilgiri langur habitat, demography and group dynamics
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Impact of biotic disturbances on the Nilgiri langur (Trachypithecus johnii) habitat, demography and group dynamics was investigated from 1985 to 1988. Wood cutting, dynamiting and pilgrimage were the distur- bances. Based on the intensity of disturbances the Nilgiri langur habitat was subjectively different iated into highly disturbed (HD), moderately disturbed (MD) and least disturbed (LD) areas. Ten groups of langur were selected: four in the HD areas and three each in the MD and LD areas. These groups were monitored to collect data on group size, composition and birth and death rates. There was loss of trees, poles and canopy cover due to firewood cutting and pilgrimage to Sorimuthayana r temple. Most of the trees cut were Nilgiri langur food plants. Dynamiting near Servalar reservoir destroyed 103 trees belonging to 10 species in a sample area of 1.2 ha. All ten species were Nilgiri langur food plants. Disturban - ces decreased birth rate and increased death rate. Increase in mean group size seen in the LD area was not seen in other two areas. Several conservation problems are identified and management recommen- dations for protection, restoration and education are given.