Feeding Ecology and Social Structure of Golden Langur (Trachypithecus geei) in Secondary Forests of Chakrashila Wildlife Sanctuary, Assam, India

Abstract

I studied Golden langurs in altered habitats to understand the consequences of habitat conditions on social organization, ecology and ranging pattern. I selected 12 groups inhabiting forest edge and forest core of Chakrashila Wildlife Sanctuary and the adjoining rubber plantation. Three groups from the different habitats were also selected for activity budgeting and ranging data collection. Instantaneous scan sampling method was used and groups were followed from dawn to dusk. Geocoordinates of the group movements were recorded at every 30 minutes interval. The overall group size of golden langur was 11.3±3.5SD, and ranged between 5 and 18. The mean group size in forest core, forest edge and rubber plantation differed significantly. Births occurred in all the months but peaked between May and September (82.6%). The mean number of births positively correlated with mean monthly rainfall. Diurnal activities varied significantly with highest time spent on resting followed by feeding, locomotion, monitoring and social for all the three groups. The core group, edge group and rubber group spent 27.33%, 26.83% and 25.27% time in feeding respectively. Food items consumed varied significantly across the seasons and across the groups with highest leaf consumption of leaf annually by core group (65.67%), edge group (59.39%) and rubber group (34.60%). Number of plant species consumed by core group, edge group and rubber group are 39, 41 and 40 respectively. Mean annual day path length among the three groups have significant difference (F2,182=11.08, p<0.001). Home range area used by core group, edge group and rubber group are respectively 29 ha, 42.25 ha and 49.5 ha, however, the spatial use of the habitats by each group varied seasonally. It therefore, appears that social organisation, activity budget, diet and ranging pattern are related to disturbance and environmental factors. The behavioural parameters may influence life-history traits if continuous habitat alteration persists.