An African forest monkey with long white fringes that feeds mainly on leaves.
Adults have white fringes along the sides of a black body and a white tuft at the end of a long tail.
In Wof-Washa Natural State Forest in Ethiopia, researchers followed two neighboring groups of Omo River guerezas for 12 months: one in natural forest and one in an adjoining plantation. The natural-forest group fed on 30 plant species, while the plantation group fed on 18. Both ate mostly young leaves. The natural-forest group ate more mature leaves and shoots and fewer fruits and stems.
Diets also featured different plants: Maesa lanceolata leaves made up a larger share for the plantation group, while Vernonia leopoldi was the largest food item for the natural-forest group. The five most-used plant species made up 83% of the plantation group’s diet and 70% of the natural-forest group’s. Plant surveys also found higher monthly availability of young leaves in natural forest. Their food mix differed within the same subspecies.
IUCN Red List (IUCN SSC Primate Specialist Group) · Least Concern (LC) · Global
The 2025 global IUCN assessment classified the Guereza as Least Concern (LC), based on an assessment dated 5 February 2024. It has a wide range and is common at many sites, especially in protected areas, although the population trend is decreasing and it is locally threatened. In parts of its range, forest loss from timber extraction and conversion to agriculture or plantations, as well as bushmeat hunting in the west, are threats.