The Tana River mangabey (Cercocebus galeritus) is a highly endangered species of primate in the family Cercopithecidae.

[1] It is endemic to riverine forest patches along the lower Tana River in southeastern Kenya.

[7] Recently, it has been suggested that 20,000 hectares of the Tana River Delta should be transformed into sugarcane plantations, but this has, temporarily at least, been stopped by the High Court of Kenya.

It is believed to sleep in trees to reduce the risk of predation and chooses this site according to its last feeding position in the area.

[12] During the dry season when food is limited, groups maintain discrete territories with minimal overlapping.

[13] The species is omnivorous, feeding on leaves, seeds, fruits, insects, and reptile and bird eggs.

The mangabey gets most of its food from subcanopy and canopy trees, although it spends most of its time feeding and moving on the ground.

[18] The forests in which it is found are naturally fragmented due to the meandering of the Tana River and its fluctuating water levels.

The forest is becoming even more fragmented due to habitat loss from human disturbance, which may reduce species' survival.

[9] Felling of canopy trees for canoe construction, wild honey collection, and palm fronds are being used for thatching and mats.

Subcanopy trees are being used for housing poles and the topping of Phoenix reclinata for palm wine collection severely impacts the resources used by the species.

[20] With the poor management of the Tana Delta Irrigation Project, habitat loss outside the reserve also continues.

The Tana and Athi Rivers Development Authority, which is in charge of the project, are now in the process of expanding to establish a sugarcane plantation, which will in turn remove more forested areas.

The project was poorly managed and was terminated after two years, leaving the wildlife service with the protection of these areas.

Tourism development is believed to be important in that it will secure the conservation of the habitat and the species with the communities around the reserve.

Tourism will benefit both the mangabey and local communities through economic development and a reduction in habitat loss.