Colours of Wildlife: Zanzibar Red Colobus

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Zanzibar Red Colobus

Willem is a wildlife artist based in South Africa. He says "My aim is simply to express the beauty and wonder that is in Nature, and to heighten people's appreciation of plants, animals and the wilderness. Not everything I paint is African! Though I've never been there, I'm also fascinated by Asia and I've done paintings of Asian rhinos and birds as well. I may in future do some of European, Australian and American species too. I'm fascinated by wild things from all over the world! I mainly paint in watercolours. . . but actually many media including 'digital' paintings with the computer!"

Zanzibar Red Colobus by Willem

A monkey for the end of the alphabet! This is a Zanzibar Red Colobus, Procolobus kirkii. While the Lesula looks like a sage among the monkeys, this one looks like a clown, with permanent make-up and funny hairstyle! Actually, their faces vary individually, allowing them to recognize each other, but all of them have the black faces with pink nose and lips, fringed by wild white hair. The belly, hind legs and insides of the arms are white; a black stripe runs up the outsides of the arms up to the upper back and shoulders; from the upper back to the base of the tail the fur is rich red-brown. The rest of the tail is greyish to white. Zanzibar red colobuses reach 12 kg/26.5 lbs in bodyweight; males are only slightly larger than females. The scientific species name commemorates Sir John Kirk, British Resident of Zanzibar, who brought this species to the awareness of scientists.

As you may have guessed, these monkeys only occur on Zanzibar, the largest island off Africa's eastern coast. Zanzibar is part of the country of Tanzania – indeed, the name Tanzania comes from Tanganyika (the name for German East Africa after the British took it over), and Zanzibar. Zanzibar has a strong Arab/Islamic colonial element. Tanganyika and Zanzibar became independent in the early nineteen sixties, and then unified in 1964 to constitute the new country of Tanzania.

Thumbless Foliovores

Colobus monkeys, in general, are a large and diverse group of mainly leaf-eating monkeys living in tropical Africa, mostly in rainforests. They are close relatives of the leaf-eating monkeys of Asia: the langurs, snub-nosed monkeys and proboscis monkeys. The name 'colobus' comes from the Greek 'ecolobóse' which means 'he cut short'. This refers to their thumbs: these monkeys either have very short, stubby thumbs, or no thumbs at all. It's not clear why they have such short thumbs; it doesn't seem to limit their agility in the trees, or their ability to manipulate their food.

Colobines in Africa fall into three groups: the single, probably very conservative Olive Colobus, then the black-and-white colobuses, and finally the red colobuses, to which this one belongs. The red colobuses are the most diverse, and also the most endangered. The closest relative of the Zanzibar Red Colobus is the Iringa/Udzungwa Red Colobus, Procolobus gordonorum, which is highly endangered and occurs quite a distance inland in the Udzungwa mountains of Tanzania. Genetic evidence shows that the two species diverged from each other about 600 000 years ago. There must have been a time when the ancestors of these two species ranged in a continuous belt across Tanzania; during the Ice Ages, it is possible that there existed a land bridge between Africa and Zanzibar, allowing the colobus monkeys to colonize it; then, when the glaciers melted and the sea level rose again, the island became cut off and the colobuses on it started evolving into a new species. Overall drier climates meant that previously more extensive forest retracted, so that now the Udzungwa red colobuses only remain in the moist mountain forest, with a vast stretch of dry savannah unsuited to colobuses separating it from the colobuses on Zanzibar.

Self-Medicating Monkeys

Most African monkeys have diets that are diverse; colobines are the vegans among them, with a very restricted diet. Leaves are much less digestible and lower in nutrients than fruits; consequently, colobus monkeys have enlarged bellies with extra entrails and four-chambered stomachs reminiscent of those of cud-chewing mammals. The food stays in there for a long time so as to digest and yield its nutrition. In addition, many leaves, especially young leaves, contain toxic substances for protection. Colobuses show some resistance to this, but the Zanzibar red colobus goes a step further, and actually medicates itself to neutralize some of these poisons! They eat charcoal whenever they can find it. Medically, among us humans, activated charcoal is used to absorb many poisons; the monkeys seem to have discovered this property for themselves. It apparently has to be learnt – so, seeking out and consuming charcoal can be considered a colobus tradition.

Apart from leaves, colobuses also eat shoots, flowers, bark, dead wood and unripe fruits. They also consume some soil, again perhaps because of poison-neutralizing compounds in it (which is also done by many unripe-fruit-eating parrots in Amazonia). Because they frequent mangrove swamps (which are partly inundated by the salt water of the sea each day), they take in a lot of salt from the mangrove tree leaves; they therefore have to drink a lot of fresh water to prevent their blood from becoming too salty. Ironically, the one thing their digestion cannot deal with is the simple sugars in sweet, ripe fruit!

Sociable Primates

Like the vast majority of monkey species, Zanzibar red colobuses are very social. They live in troops of mostly 30 to 50 animals. They're not territorial; groups can mingle. Within each troop, though, there's typically a dominant male. He allows some other adult males in his troop, but typically there are about twice as many females as males. The monkeys are very communicative; as I've said, they can recognize each other's faces, and can surely tell a lot from each other's expressions. They also have a large repertoire of calls. Their voices are higher than those of the black-and-white colobuses, which have deep, croaking calls. In this species, males not only tolerate each other, but even groom each other. Because they are so social, these colobuses have a loud call which any individual utters when it is for some reason cut off from the rest of the troop and feeling alone and vulnerable – which sends the other monkeys scurrying to its rescue!


Sadly, this is one of the many highly endangered primate species in the world. Being entirely confined to Zanzibar Island is the first factor: they only live there, so naturally their population is much constrained. But humans are also living there, and have cut down much of the forest and thicket in which the monkeys used to live. Then there's ongoing conflict between people and monkeys. There is a superstition that the monkeys are poisonous – this might have something to do with their poisonous diet, and also they have a rank smell. But the people believe the monkeys will cause trees to die by eating them, and thus are unwilling to tolerate them in their orchards. Nevertheless these monkeys do enter farms a lot, and even thrive in these altered environments where tolerated. They're currently given complete legal protection, but this doesn't completely stop people from persecuting them, even killing them to eat them. Then there's the opposite problem, where people actually like them and capture young ones for pets! All of this impacts the stability and social order of the troops. Like many island animals, they don't breed very prolifically, a typical female giving birth to one or two babies every two years or so. An attempt has been made to introduce these monkeys to the other East African island of Pemba; this hasn't been very successful.

At present, the laws protecting this species don't seem to be doing much. Part of Zanzibar has been declared a nature reserve, the forest at being conserved, giving the monkeys at least a place in which to live. Their current population is estimated at 1600-3000 individuals. Conservation organizations are trying to combat negative superstitions and to raise awareness and appreciation of the uniqueness of this species among the people of Zanzibar. This monkey with its striking frightened-clown face can serve as a kind of mascot for the island and for conserving its unique natural heritage. Ultimately one hopes that more tourists will come to visit Zanzibar to see the monkeys, supporting the economy and giving people more reason to care about, and for, these unique primates.

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