The black capuchin (Sapajus nigritus), also known as the black-horned capuchin, is a capuchin monkey from the Atlantic Forest in south-eastern Brazil and far north-eastern Argentina. Historically, it was included as a subspecies of the tufted capuchin. Taxonomy The black capuchin was originally named Cebus nigritus or Cebus apella nigritus, and while this has been changed, a lot of sources still name the black capuchin as part of the genus Cebus. Social behaviour Group size The black capuchin is a social animal. It likes to live in groups, usually consisting of 6 to 20 members, and is hierarchal. Despite the fact that these groups tend to be made up of more females than males, the alpha female of the group is submissive to the alpha male. The size of the group operates as a function of food availability; size and cohesiveness are highest when food is readily available. When food is scarce, black capuchins split up into smaller groups to cover more ground on a per capita basis. This is observed both seasonally in the short term and over the course of years in the long term. The larger the group, the more food they need, which in turn leads to more travel. Females are, for the most part, philopatric. Although the rare female can be observed leaving her natal group, dispersal is largely a male phenomenon. When females do leave, they do so gradually, retreating first to the group’s periphery before breaking away entirely. Aggression Males are apt to kill the offspring of competing males, especially during power struggles. When females are aggressive, it is generally in food squabbles, but even these conflicts are generally relegated to the male portion of the population, with one study finding that females participated in only 19% of such fights. When they do so, however, they are almost always the aggressor (93% of the time in the same study), their favourite target being juveniles. Such conflict perhaps arises due to the tendency of dominant females to take control of patchy areas of food. Communication Communication within groups consists of bodily, facial and vocal communications. One example of this is the 'scream embrace mechanism’, a high pitched called used to regroup (usually male) members of a group. Bonding Grooming plays a central role in bonding between black capuchins. It serves the obvious purpose of hygiene, evidenced by how the monkeys focus their efforts on