The Golden Bellied-Mangabey is a rare endemic to the Democratic Republic of Congo. I saw these primates in 2013 while habituating bonobos for the Max Planck Institute. Very little is known about this species. So let's get some basic facts down.
Common Name: Golden-Bellied Mangabey
Other names: N/A
Latin name: Cercocebus chrysogaster
Location: Democratic Republic of Congo
Status: Data deficient
So from the above information, or lack of it, you can see very little is known about this species. It has never been studied in the wild, only in captivity, and that is limited. In the wild few people, aside from those who live in the forest, have ever seen it. Very few westerners have seen this species. Of these few I am the only person known to have taken photos and even captured video footage.
They are endemic to DRC and much like the bonobo they are only found south of the Congo River. What is know is they live in groups of between 15-100 individuals. Other than this not much is known. I will tell you of my observations.
I was following my group of bonobo one day and they headed into a swamp. To leave they climbed up a steep bank. As I followed I lost the group but when I reached the top I was surprised to see a different primate. The golden-bellied mangabey. There were about 50 individuals. What was surprising was they showed no fear to either me or the bonobos. That was surprising in two ways. First bonobos hunt monkey and other monkeys flee from them. Here these were as one group. I guess bonobo don't hunt golden-bellied mangabey? The fact they were not afraid of me shows something else. They are naive. This means they have no fear of humans. In fact some came for a closer look. I guess they have never been hunted in Lui-Kotale?
I stayed with the group for around half an hour before the bonobos moved off. I wrote a more detailed account in my book (available on amazon, click here). I will leave you with the footage I captured.