Easily observed in the trees above the research camps or above the Park's headquarters in Bomassa, the Old World monkeys found in Nouabalé-Ndoki National Park are a large family of monkeys remarkable for their diversity of colors and appearances. Their size also varies greatly, ranging from 40 to 70cm for some species, yet they all belong to the same family of primates, cousins of the great apes, and therefore of humans. Although not considered endangered, these species are found in every bushmeat market in the region, and their survival could quickly be threatened.