The northern muriqui was once widespread in the Atlantic Forest region, but today there are only a handful of sub-populations in nine or more protected areas, including Rio Doce State Park, Caparaó National Park, Serra do Brigadeiro State Park, and Augusto Ruschi Biological Reserve (1) (2) (4). The total known population is very low, at only 300 to 400 individuals (2), and the largest sub-population recorded has only 157 individuals, which severely limits the group’s breeding potential (1). This species is threatened by habitat destruction as it occurs in one of the most populated and industrious region of Brazil (4). Vast tracts of forest have been lost, and the remaining healthy forests are fragmented and at risk of being destroyed in the future. In addition, these large primates were an important food source for people in the region and have been widely hunted (4).