The toque macaque (; Macaca sinica) is a reddish-brown-coloured Old World monkey endemic to Sri Lanka, where it is known as the rilewa or rilawa (Sinhala: රිළවා), (hence "rillow" in the Oxford English Dictionary). Its name refers to the whorl of hair at the crown of the head, reminiscent of a brimless toque cap. Taxonomy The generic name Macaca is from Portuguese macaco, of unclear origin, while sinica means "of China," even though the species is not found there. There are three recognized subspecies of toque macaques: Macaca sinica sinica, dry zone toque macaque or common toque macaque Macaca sinica aurifrons, wet zone toque macaque or pale-fronted toque macaque Macaca sinica opisthomelas, highland toque macaque or hill zone toque macaque M. s. opisthomelas is similar to subsp. aurifrons, but has a long fur and contrasting golden color in the anterior part of its brown cap. The three subspecies can be identified their head colour patterns. Description With age, the face of females turns slightly pink. This is especially prominent in the subspecies M. s. sinica. Distribution M. s. sinica is found from the Vavuniya, Mannar to the lowlands of Anuradhapura, Polonnaruwa, Puttalam, and Kurunegala; and along the arid zone of the Monaragala and Hambantota districts. M. s. aurifrons can be found sympatrically with the subspecies M. s. sinica within intermediate regions of the country in Kegalle and parts of Kurunegala. It is also found in south-western parts of the island in the Galle and Matara districts near Kalu Ganga. M. s. opisthomelas has recently been identified as a separate subspecies. It can be found in the entire south-western region of Ratnapura and in the Nuwara Eliya districts. It is also found around Hakgala Botanical Garden and other cold climatic montane forest patches. Behaviour and ecology Social structure Social status is highly structured in toque macaque troops and dominance hierarchies occur among both males and females. A troop may consist of eight to forty individuals. When the troop becomes too large, social tension and aggression towards each other rises, causing some individuals to leave. This is noticeable in adults and sub adults, where a troop may consist largely of females. Newly appointed alpha males show aggressiveness towards females, causing the females to leave the group. Fighting within the troop can cause serious injuries including broken arms. Young offspring of a troop's alpha female will typically receive better sustenance and shelter than