Unveiling the Secret: The Grey-cheeked Mangabey – Uganda’s Elusive Forest Dweller. Grey-Cheeked Mangabey (Lophocebus albigena); The thick rainforests of Uganda are rich in bio-diversity and host some of the most interesting primates of Africa, including the enchanting Grey-cheeked Mangabey. This is one of the best-looking primates that are usually found in quite lively social groups....