Sterilization by endoscopic tubectomy of female long-tailed Macaques (Bali, Indonesia) - surgical protocol and behavioural impact

Abstract

Through this study, I will first describe the main types of contraception or sterilization techniques found in different species of primates. These methods involve the use of chemical molecules or surgical protocols. By explaining why surgical and permanent methods are better for the Macaca fascicularis females in the Ubud Monkey Forest, I will describe the tubectomy procedure used during a sterilization campaign. Finally, I will study the impact of sterilization on the behaviour of females by comparing two groups, the one-year-sterilized females (2017) with the newly sterilized females (2018).

Although the Ubud Monkey Forest is the ideal example of the coexistence between humans and primates, there has been a recent emergence of conflicts. In fact, primate provisioning and protection, as well as the lack of natural predator have led to a significant macaque population growth due to an increase of birth rates and a decrease of mortality. To deal with this population growth and very high local density, a birth control program has been initiated in 2017, aiming the sterilization of females with a tubectomy approach. It consists of a surgical ligation of fallopian tube by laparoscopy. This technique has been chosen among other sterilization or contraception methods as it presents the advantages for wild primates of being permanent, highly effective and safe.

Regarding the effect of this sterilization on female behaviours, my observations indicate that three categories of behaviour significantly varied between 2017 and 2018 sterilized females: agonistic, sexual, and caring behaviours. 2017 sterilized females were more targeted for aggressions, they spent more time involved in sexual behaviours and less time devoted to infant-caring behaviours compared to 2018 sterilized females.