The Sulawesi crested macaque (Macaca nigra) is a terrestrial macaque distributed in the northeastern part of Sulawesi Island, Indonesia. Body length is 45–60 cm, males are larger than females, the entire body is black with a distinctive crest of hair and pink buttocks. It mainly eats fruit, and when fruit is scarce it also consumes insects, young leaves, reptiles, and agricultural crops. Troops are matrilineal and number about 50–100 individuals, exhibiting complex social behavior and communication. Reproduction shows no clear seasonality, although mating is more common in June and August; gestation lasts about 5–6 months and usually results in a single offspring. Populations have declined rapidly due to hunting and habitat destruction, and the species is listed as Critically Endangered (IUCN Category I A).