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!"
Everything's better with monkeys! This week I bring you a Moustached Monkey, or Moustached Guenon, Cercopithecus cephus. Moustached monkeys are about the size of cats, ranging from 2kg/4.4lbs to 5 kg/11 lbs in bodyweight (males being larger than females), and with tails as long as the rest of their bodies. Like others of their group, their forelimbs are shorter than their legs, which are adapted for powerful jumping.
Please distinguish this species from the little moustached monkey of South America, the Emperor Tamarin, which has a most distinguished moustache quite different in appearance. The tamarin is also only distantly related – as are all the South American monkeys to African monkeys. I hope to feature the South American ones sometime, but for now, let me speak of the monkeys of Africa.
Africa has an astounding diversity of monkeys – most quite unknown to the general public, and many severely endangered. I've already featured here a variety of the larger baboons and their relatives; Mangabeys, De Brazza's monkeys and vervets. This week's monkey is related to the vervet, but different in many ways. Moustached guenons are of a group of small, rainforest-inhabiting monkeys, with brightly coloured faces – these are generally referred to as the 'cephus'-group of monkeys. These species replace each other geographically, each inhabiting a particular patch of the vast, equatorial, lowland rainforest belt of Africa. The westernmost species is the Lesser Spot-Nosed Monkey, Cercopithecus petaurista, which ranges from Sierra Leone to Benin, while the easternmost is the Red-Tailed, ranging as far east as Uganda. The moustached guenon occurs pretty much in the middle, in southern Cameroon, and throughout Gabon, Equatorial Guinea and the Congo (not the DRC), and just entering northwestern Angola. Of these various species, each has a distinctive face pattern, and other parts of the body such as the tail or the belly can be brightly coloured as well. Moustached guenons come in two sub-species: the typical one has a red tail, while the other has a grey tail.
Cephus-monkeys are all small and very active. They are adapted to move rapidly through the rainforest at high levels, running amidst the branches and leaping from tree to tree. Admittedly in the dense rainforest the threes are very close together, so these monkeys are not quite as prodigious at leaping as some other primates. They don't come down to the ground, spending most of their time at high levels. They occur in small bands, the majority of which are adult females with their babies and young offspring. Each band has only a single dominant male. The females however are also quite assertive, and will chase females of a competing band out of their territory, and will even drive away unaffiliated, solitary males!
With their faces being so brightly coloured and patterned – natural permanent make-up – it is clear that visual appearance is important to these monkeys. They have excellent eyesight and can distinguish colours better than most mammals. Their distinctive coloration helps them to spot and keep track of each other. Cephus monkeys meeting, greeting or displaying to each other, do so with wagging or jerking movements of their heads.
But their fine sense of sight also helps them put food in their bellies. They eat mainly fruit, which in the moist, equatorial forests is available year-round. But there might be shortages lasting for days or weeks in certain areas, in which case they can get by on chewing leaves and soft stems of some of the trees and shrubs. Amidst the fruits and leaves they also find insects – indeed, the females will peer and scan the leaves for insects, being able to spot them from a distance and pouncing on them. It's been found that the females of the troop include a greater percentage of insects in their diet than the males do – and that's because the dominant male must spend much of his time watching over his troop members and keeping an eye out for threats, rather than for insects!
It's not just visual signals that are important to these monkeys. They've good hearing as well, and will communicate to each other with a variety of sharp chirps and barks. They're often found sharing their habitats with other species such as colobus monkeys, mangabeys, and guenons of different species- groups. These different species often join into mixed troops, sorting themselves out by ecological role, each targeting a particular kind of food with a particular foraging strategy. The cephus monkeys are able to spot and get to fruiting trees quicker than the others, but because of their small size, can easily be driven off by the larger species. But an interesting interaction has been noticed. While the cephus monkeys have calls that are quite loud, the larger gentle monkeys (a different and also very diverse group of species and subspecies) have calls that are much louder. The little cephus monkeys often synchronize their calls with those of the larger gentle monkeys – a kind of duet – to make them carry more weight, so to speak! In turn the larger gentle monkeys benefit when the more alert and keen-eyed cephus monkeys spot danger, their warning calls being immediately intelligible to all the monkey species in these mixed troops.
At present, moustached monkeys are still widespread and abundant. But they are hurt by ongoing clear-cutting of forests in equatorial Africa, as well as by indiscriminate hunting. There is great need for proclaiming more forest reserves in central Africa to benefit this and many other rainforest species – animals and plants.