Social Behaviour and Communication Among Wild Lion-Tailed Macaque (Macaca silenus) in the Indira Ganghi Wildlife Sanctuary, Tamil Nadu

Abstract

This study on the social behaviour and communication among wild lion-tailed macaque was carried out between November 2000 and April 2001, on a group of lion-tailed macaques that inhabit the wet evergreen Puthutotam forest fragment. located within the Indira Gandhi Wildlife Sanctuary in the Anaimalai hills, Tamil Nadu.The troop consisted of 16 to 19 animals. For the purpose of this study, social interactions within and between adults and subadults of both sexes were considered. Focal animal sampling and instantaneous scan sampling was thus conducted on only ten identified individuals (four males and six females) in the troop. A complete ethogram describing all behaviour observed during the period of the study was repared. The time-activity budget was calculated for the troop. The predominant behavioural states among all the individuals were Active Forage (mean ± SD of 22.4 ± 0.08%), Active Feed (17.0 ± 0.05%), Sit (16.6 ± 0.04%), Move (13 ± 0.030/0), Passive Forage (6.8 ± 0.02%) and Passive Feed (6.5 ± 0.02%). The adult males and females of the study troop differed in the proportion of time spent by them in the different behavioural states. Autogroom and Allogroom accounted for the principal difference between the sexes. Adult males spent relatively greater time Autogrooming than females, while females allogroomed relatively more. Dominance ranks were calculated independently for males and females in the study troop. Among both males and females, rank position in the dominance hierarchy appeared to be influenced strongly by body size. This is an unusual finding for the females of cercopithecine primate species, implying the existence of an unique individual-based dominance hierarchy among the study females. There was i.e remarkable similarity in the frequency with which dominant and subordinate females displayed virtually all behaviours towards each other in dyadic interactions. This provides support to the prevailing view that lion-tailed macaques indeed display an egalitarian nature. Classification of the gestures and vocalisations were observed to be largely dependent on the dominance rank of the individuals. with certain gestures being characteristic of submission. Males and females showed differential use of the gestures and expressions.