Written by: Hagai Zvulun
The Zanzibar red colobus (Procolobus kirkii), otherwise called the Kirk’s red colobus, it is historically endemic to Unguja Island in the Zanzibar Archipelago. It is found in a variety of habitats such as ground water forests, coral rag thickets, mangrove swamps and in secondary forests.
Matembezi safaris takes a closer look at the charismatic Zanzibar red colobus this Monkey Day!
The Zanzibar red colobus lives in mix troops, with a higher ratio of females to males and an average troop size of 15-30 animals. Troops tend to be larger within protected areas.
The monkey’s range was extended when a troop of 15 individuals was introduced from Unguja to the Ngezi-Vumawimbi forest on Pemba Island in 1973, also part of the Zanzibar Archipelago. The Pemba troop is now at 40 individuals.
Like all other colobus monkeys, the Zanzibar red colobus is a foliovore (a herbivore that specialises in eating leaves). A diet of leaves holds little nutritional value, with high levels of hard-to-digest cellulose and less energy than other food sources. Leaves also often include toxic compounds and it takes a specialised gut to process all this greenery. This monkey has evolved to deal with its unique dietary niche through an elongated digestive tract and a slow metabolism. It is its gut that is responsible for the colobus’ cute potbelly.
They also enlist the use of symbiotic bacteria in their gut that releases the nutrients from their tough and fibrous food. They actively seek younger leaves, as those are higher in their nutritional value and lower in fibre and toxins. A behavioural response they have had due to their slow gut is that they are more sluggish than their other monkey cousins.
The name colobus comes from Greek ekolobóse, meaning “he cut short”, which refers to the lack of opposing thumbs in colobus monkeys. The remaining four digits are long, strong and aligned to form a strong climbing hook that serves them well in their arboreal life.
The total population of the Zanzibar red colobus in the wild is estimated at 2,000-3,000 individuals, making them one of the most endangered monkeys in Africa. Furthermore, about 50% of their population is found outside of protected areas, and their habitat is constantly being degraded by firewood collection, charcoal production and conversion of coastal thicket to agriculture.