Observation of Grooming Behaviour in Wild Capped Langur Trachypithecus pileatus

Abstract

The manual dexterity of primates allows them to use their hands to clean their skin and hairs as well as maintain a good social relationship with intra-group members. This behaviour is described as grooming. It is the most common affinitive behaviour among primates and may be directed to the self (Autogrooming) or with a intra-group member (Allogrooming or social grooming). Auto-grooming is often determined by the site accessibility, while social grooming is concentrated on parts inaccessible to the groomee. In this paper, we have recorded the grooming behaviour and patterns in capped langur (Trachypithecus pileatus) in Pakke Wildlife Sanctuary, Arunachal Pradesh, India. Focal-animal sampling technique was adopted for recording the grooming behaviour. The following behavioural observations in relation to time spent on grooming, grooming bouts and length, and grooming site preference are studied with the aim to assess the diurnal active time spent on grooming patterns of capped langurs. Of the 1683 hrs of observation, T. pileatus spent totally 60.95 hrs in grooming behaviours including 32.9 hrs (54%) for social grooming and 28.1 hrs (46%) for auto-grooming. A total of 1934 grooming bouts were recorded during the observation period. Of these, 58% bouts were for auto-grooming followed by 42% for social grooming. Maximum (15 min) grooming bout length was recorded in social grooming prior to copulation in compare to auto-grooming (8 min). Seven major body regions namely dorsal, ventral, lateral, ano-genital, face and head, tail and hind limbs were frequently observed to be groomed by capped langur. Of the total social grooming bouts (817), maximum (30%) was estimated on the dorsal side followed by 23% on ventral side, 21% on ano-genital region, 14% on lateral side, and 11% on face and head. Social grooming is adopted as tool to manipulate reproductive behaviour and to formulate survival strategies of the species.