|Common Name||Black-headed Uakari|
|Range||Brazil, Colombia, and Venezuela.|
The species Cacajao melanocephalus was previously named the black-headed uakari and two subspecies were thought to exist: Cacajao melanocephalus melanocephalus (black-backed uakari) and Cacajao melanocephalus ouakary (golden-backed uakari). However, in 2008 a new black uakari was discovered and the species group was reassessed by Boubli et al. using morphological and molecular analyses. Cacajao melanocephalus ouakary was found to be a junior synonym of Cacajao melanocephalus but its common name, golden-backed uakari, replaced the previous one, black-headed uakari. Cacajao melanocephalus melanocephalus was elevated to species status as Cacajao hosom (the Neblina uakari), and the new species was named Cacajao ayresi (Aracá uakari).
The golden-backed uakari is characterized by a black haired head, black hairless facial skin, black lower limbs and hands, black soles on hands and feet, and a reddish hued flank, tail, and upper limbs. They are noted for having a particularly short and non-prehensile tail and highly specialized teeth.
Sexual dimorphism is present, with females being slightly smaller than the males, having a mass generally less than 3 kg compared to an overall species' mass ranging from 2.5 to 3.7 kg.
They typically live in groups of 5-40 individuals, but occasionally more than 100 may come together. Individuals within a subgroup exist in close proximity and interact frequently. The uakari are diurnal. They move around by walking and running on all fours and even climbing and galloping. Leaping is the main method of travel, allowing them to cover a distance of 10 meters in one leap. Swimming is done only when required, as when they accidentally fall into the water.
Newborn infants range from 25% to 67% of the mother’s body length. After birth, the infants follow the mother for a year and a half, being carried on her back or front side.