In the forests of North Sulawesi lives a rather majestic monkey species, named for their colouration and distinctive hair style! Sulawesi crested black macaques are known locally as Yaki, and are one of seven species of macaque endemic to the Indonesian island of Sulawesi, found nowhere else in the world.
Apart from an island 345 miles from Sulawesi, Pulau Bacan, crested black macaques’ range is restricted to small forest fragments in the province of Minahasa, where they live in large multi-male multi-female groups with an alpha male sitting at the top of the hierarchy. They are sexually dimorphic, meaning the males look different to the females, and are in fact almost twice their size, with bigger canine teeth often used in displays and in aggressive encounters. Characterised by their distinctive crest of hair, entirely black face and body colouration and bright pink, heart shaped bottom (ischial callosities) these monkeys are a striking and iconic species.
They are predominantly frugivorous (fruit eaters), with fruit from around 150 tree species making up about two thirds of their diet. They are semi-terrestrial, spending time on the ground moving quadrapedally. Communication between crested black macaques involves a variety of vocalizations and postures performed in different situations. These are used to mediate social interactions between individuals and other groups, and to increase group cohesion, strengthening the bonds within the groups.
The largest population of crested black macaques are found in Tangkoko Nature Reserve. Consisting of lowland tropical rainforest, the reserve covers an area of 8,867 ha and ranges from sea level to 1,350 m. These monkeys represent a key species within this ecosystem, and the study of their population and distribution can provide an indication of habitat quality with far-reaching implications for many other plant and animal species. With a wealth of other species dependent on the same habitat, protecting the forest homes of Yaki will ensure the survival of the impressive biodiversity of this unique area.