[4] Some recent authorities include P. tephrosceles, P. foai and P. tholloni as subspecies of P. rufomitratus instead of recognizing them as separate species.

[9] 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.

They put a large amount of research and study into the conservation of the Tana River red colobus.

They found that only 37% of the red colobuses lived inside the preservation itself, which has brought the conservation strategy into question.

[13] A survey conducted in 1987 concluded that since 1975 there has been approximately an 80% decline in the numbers of Tana River Colobus monkeys.

Habitat disturbances, changing farming practices, and the altering course of the river were found to be the main reasons for endangerment.

[14] Another developing threat to the Tana River red colobus is the introduction of parasitic diseases to their habitats.

Their stomachs are large and have three chambers, and carry a specific bacterium which helps to ferment and digest the leaves.

[17] Tana River red colobus monkeys tend to be sedate and quiet creatures.

The average annual rainfall is between 500 and 600 mm, with the wettest months being March and April and the driest being November and December.

[18] A study was done in 1988 to determine what was causing the drastic decline of the crested mangabey and the Tana River red colobus.

[19] The Tana River red colobus has a polygynous mating system especially when only one male is present.