About Colobus guereza Rüppell, 1835
This species, the mantled guereza (scientific name Colobus guereza Rüppell, 1835), has a distinctively patterned coat that is mostly black, with long silky white fringes called a mantle running along the sides of its body and tail. The mantle bands start at the shoulders, extend along the back, and connect at the lower torso. The guereza has a long tail that ends in a white tuft; the proportion of the tail covered by this tuft varies across subspecies. For example, the tail of C. g. guereza is gray until the white tuft, which covers half the tail length, while the white tuft of C. g. caudatus makes up 80% of the tail. Mantle color can range from white to cream or yellow. The guereza’s face is framed by white hair, and it has bushy cheek hairs, plus a white stripe on the thigh. Infants are born with pink skin and white hair; their skin and hair darken as they age, and they reach full adult coloration by three to four months, with males typically developing adult coloration earlier than females. On average, males weigh between 9.3 and 13.5 kilograms (21 to 30 lb), while females weigh between 7.8 and 9.2 kilograms (17 to 20 lb). Average head and body length is 61.5 centimetres (24.2 in) for males and 57.6 centimetres (22.7 in) for females. Like most colobi, mantled guerezas have a small, vestigial thumb. Subspecies show varying patterns of dental sexual dimorphism: in some subspecies males have larger teeth than females, in others females have larger teeth than males, and some subspecies show no significant size difference between the teeth of males and females. The mantled guereza is found across Equatorial Africa, ranging from Nigeria and Cameroon in the west to Ethiopia, Kenya, Uganda, and northern Tanzania in the east. It inhabits both deciduous and evergreen forests, and primarily lives in forests and savannah woodlands, often extending into highland and montane forests. It can also occupy other forest types including primary and secondary forests, such as riparian forests near fresh or brackish water, gallery forests, and upland forests. It is particularly common in forests near rivers and lakes and at high elevations, and can be found at elevations up to 3,300 metres (10,800 ft). This species prefers secondary forests over old-growth forests when given a choice, likely because secondary forests have more food trees and the plant species there have weaker chemical defenses. Mantled guerezas are sometimes also found in swamps, and in human-made habitats such as Eucalyptus plantations, which they may visit when they have nutritional deficiencies. The mantled guereza is primarily arboreal, but will sometimes descend to the ground to forage and travel, possibly more often than most other colobines. It is diurnal, and rests for up to half of each day; foraging and travelling are the next most common daily activities. After dawn, guereza groups leave their sleeping trees, and return to them again at dusk. The species takes long rest periods between periods of moving and feeding throughout the day, while other activities including grooming, greeting, playing, and vigilance occur less frequently. Despite a common reputation as an exclusive leaf-eater, the mantled guereza is not an obligate folivore. While it eats mostly leaves and fruit, its diet is quite variable, and can also include bark, wood, seeds, flowers, petioles, lianas, aquatic plants, arthropods, soil, and even concrete from buildings. The proportion of each food type in its diet varies by location and time of year. Nutritional factors including protein, tannin, and sodium levels in leaves influence the guereza’s food choices, and it will occasionally travel longer distances to reach plants with higher nutrition levels. Leaves usually make up over half of its diet, though fruit may be eaten more often in some seasons. When foraging for leaves, mantled guerezas prefer young leaves over old leaves. When feeding on fleshy fruits, they prefer to eat unripe fruits, which may reduce competition with other primates that feed on ripe fruits. While the guereza consumes many different plant species, only a small number of these make up most of its diet at any specific site. Like all colobi, the mantled guereza can digest leaves and other plant fibers using a large, multi-chambered stomach that hosts specialized bacteria in certain regions. Like most colobines, it prefers foods with high fiber content that its specialized stomach can process easily. The mantled guereza’s main predator is the crowned hawk-eagle, but it is also hunted by other birds of prey including Verreaux's eagle. Common chimpanzees are known to hunt guerezas, and leopards are also counted as possible predators. Mantled guerezas have a polygynous, harem-based mating system. Both males and females initiate half of all mating solicitations. To solicit mating, an individual will walk near its potential partner and make low-intensity mouth clicks or lip-smacks. During copulation, the male holds onto the female’s ankles and body. Most matings occur between individuals from the same social group, though extra-group copulations have been recorded. In multi-male groups, more than one male may mate with the group’s females. The gestation period lasts 158 days, and the interbirth interval is between 16 and 22 months. Newborn guerezas depend on their mothers for support and must cling to them. As they grow older, infants can move independently but still return to their mothers regularly. Infants receive most of the attention from other group members. Other females in a group may handle an infant, though infants are only comfortable with their own mothers. Males usually do not pay much attention to infants until they are four to five weeks old. Infants can eat solid food by around eight to nine weeks of age, and are fully weaned by fifty weeks, at which point they no longer need to cling to their mothers.
