Masturbation in a Free-ranging Male Long-tailed Macaque Macaca fascicularis (Raffles, 1821) on Mindanao Island, Philippines

Abstract

Long-tailed macaques in the Philippines are understudied in terms of ecology and behavior, which includes their sexual behaviors, in their natural habitats. Masturbation is a natural, auto-erotic behavior rarely observed in the wild in most non-human primates. In this paper, we report an act of masturbation by a free-ranging male long-tailed macaque in a beach forest at an eco-tourism site in Tagum City, Mindanao Island, Philippines. The masturbation was performed by a sub-adult male resting on the handrail of a wooden staircase. A few seconds after masturbation, ejaculation was achieved. Although more detailed observations are needed, it is likely that limited access to female mates contributed to the male’s self-stimulation. This further calls for more scientific explorations on reproductive and non-reproductive sexual behaviors of long-tailed macaques in the wild. Moreover, this can be crucial for conservation purposes such as its application to the non-invasive collection of semen samples in wild populations.