Population dynamics of a group of lion-tailed macaques (Macaca silenus) inhabiting a rainforest fragment in the Western Ghats, India

We observed the overall population dynamics and number of births and deaths in identified individuals between January 2002 and October 2005, in a large group of lion-tailed macaques in the Anaimalai Hills of the Western Ghats in the south Indian state of Tamilnadu. The group inhabited an isolated rainforest fragment located inside a private tea/coffee garden. The group size increased from 56 in January 2002 to 84 in October 2005. All females reproduced, and the interbirth interval was 23.18 months. Of the 37 infants born between 2002 and 2005, only 1 died providing an infant survivorship rate of about 97.3%. Although births occurred in all months, most of the infants were born between February and March, and this pattern of births was consistent over the years, indicating a major birth peak in this species. The population growth rate in this unusually large group was found to be higher than even in those groups of lion-tailed macaques that inhabit large and relatively undisturbed rainforest complexes. This high growth rate could be attributed to the availability of abundant cultivated fruit plants including commercial crops such as coffee seeds. The observations provide a perspective for the management of other groups of this endangered species inhabiting rainforest fragments.