Effects of Sterilization on social organization and behaviour of free ranging rhesus macaque (Macaca mulatta

Abstract

Non-human primates are frequently at conflict with humans due to their adaptability towards human-modified environments. Rhesus macaques (Macaca mulatta) co-occur with humans throughout the North and Central parts of India. In the past two decades, there has been a significant increase in the intolerance towards macaques as they are continuously forced to share space with humans. Using birth control to limit population growth is believed to be an ethical alternative to culling. Hence, owing to the human-macaque conflict in Himachal Pradesh, the State Government and Forest Department of the state initiated the ‘Monkey Sterilization Programme’. The study was conducted to understand and assess the consequences of long-term sterilization on the macaques’ social organization and in turn, on their behavior. Field work for sampling was carried out from December 2019 to March 2020. To address the set objectives, a 12-day survey was pursued within a radius of 31 km of a Monkey Sterilization Centre at Una, Himachal Pradesh, to understand the social organization of rhesus macaques in the study area. An ethological study was carried out with a group of 21 individuals of rhesus macaque to understand their behavior. The results indicate that the mean group size of rhesus macaque in Una was 12.27±10.24SD, is relatively smaller when compared to other sites e.g., North India (41.9), Central India (41.9), Bangladesh (urban) (41.3) and Bangladesh (rural) (30.2), where there was no sterilization of individuals done. Also, the size of the group in the population was much smaller (~51% of groups).