| Mantled guereza[1] | |
|---|---|
| Mantled Guereza at the Henry Doorly Zoo | |
| Conservation status | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Primates |
| Family: | Cercopithecidae |
| Genus: | Colobus |
| Species: | C. guereza |
| Binomial name | |
| Colobus guereza Rüppell, 1835 |
|
| Mantled Guereza range | |
The mantled guereza (Colobus guereza), also known simply as the guereza, the eastern black-and-white colobus,[2] or the Abyssinian black-and-white colobus,[3] is a black and white colobus monkey, a kind of Old World monkey. It is native to much of west central and east Africa, including Cameroon, Equatorial Guinea, Nigeria, Ethiopia, Kenya, Tanzania, Uganda and Chad.
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There are several distinct subspecies of this colobus:[1]
The mantled guereza has a distinctive pelage, being mostly black with a white mantle, also known as an ornamentation, and tail tuft. The bands that make up the mantle extend from the shoulders to the hips and connect around the lower torso. The tail tuft varies in how much it takes up along the tail. Subspecies vary in color variations of these features.[4] There is also white hair surrounding the face with the hair between the cheeks being bushy. The thigh has a white stripe.[4] The guereza typically weighs 9.3-13.5 kg (20.5-29.8 lbs) and 7.8-9.2 kg (17.2-20.3 lbs) for males and females respectively.[5] The head and body length averages 61.5 cm (24.2 in) for males and 57.6 cm (22.7 in) for females.[5] Like most colobi, the guereza has a reduced thumb that is rudimentary.[5] There is variation among the subspecies in dental sexual dimorphism. In some, there is lesser difference between those of the males and females, in others, males have larger teeth than females and in others the reverse is true.[6]
The guereza is distributed throughout Equatorial Africa. It ranges from Nigeria and Cameroon in the west though the northern Democratic Republic of the Congo and southern Sudan and into Ethiopia, Kenya, Uganda and northern Tanzania in the east.[4][5] Guerezas live in both deciduous and evergreen forests. They mainly inhabit forest and savanna woodlands and often extend into highland and montane forests.[7] They can be found in other forest habitats, both primary and secondary, such as riparian, gallery and upland forests. They are particularly common in forests near river and at high elevations.[8] They can be found in elevations as high as 3300 m (10,826.8 ft).[9] This species prefers forests of secondary growth and chooses them over old growth forests when both are available.[10] It is likely that the guerezas prefer second growth forests due to the greater plant species diversity in some of them and weaker chemical defenses from the plants.[10] Guerezas sometimes visit swamps[11] as well as human-altered habitats such as eucalyptus plantations, which may be visited when the monkeys need to make up for nutritional deficiencies.[9]
Despite its reputation as a leaf-eater, the guereza is not an obligate folivore.[7] While it mainly eats leaves and fruit, its diet is quite variable. It may consume bark, wood, seeds, flowers, petioles, lianas, aquatic-plants, arthropods, soil and even concrete from buildings The amount of each food item in their diet varies by area and time of year. Leaves usually make up over half of their diet but fruits occasionally predominate.[7][9] When foraging for leaves, guerezas prefer young ones over old. With fleshy fruits, guerezas prefer to eat them unripe, which may serve to reduce competition with primates that eat ripe fruits.[12] The guereza consumes a number of species but only several make up most of its diet at a specific site.[11][12] Like all colobi, guerezas are able to digest leaves and other plant fibers with a large, multi-chambered stomach that contains bacteria in certain areas.[13] The main predator of the guereza is the crowned hawk-eagle.[14] Other birds of prey that prey on it include the Verreaux's eagle.[9] The common chimpanzee is known to hunt the guereza.[15] The leopard is a another potential predator.
This species is primarily arboreal, but does sometimes descend to and travel on the ground, perhaps moreso than most other colobines. The guereza is diurnal, being active during the daytime. It spends most of the day resting.[16] The second most common activity is usually feeding, although traveling is sometimes the second most common.[16] During the day, guerezas have long rest periods in between periods of moving and feeding. Sometime after dawn, guerezas leave their sleeping trees and later return to them at dusk.[16] To a lesser extent, other activities are preformed, including grooming, greeting, playing and being vigilant.
Guerezas live in cohesive social groups usually containing of 3-15 members.[17] The groups usually contain one male, several females and juveniles. In some populations, groups containing several males are common. In multi-male groups, interactions between males tend to be aggressive with one being dominant. Some males may be forced out of the group.[16] Multi-male groups may contain father-son pairs or unrelated males.[18] Males that are not part of groups either live solitarily or with other 0utside males in bachelor groups. The females and juveniles form the core of the social groups and they are matrilineally related.[16] Females rarely disperse from their natal groups, expect possibly when they dissolve.[16] Males on the other hand, usually leave as subadults or adults. They may start out being solitary and or in bachelor groups. They gain entry into a social group either by being on the periphery or staging a takeover.[9] Within the main social groups, most interactions tend to be friendly. Allogrooming is an important part of guereza interactions and mostly occurs between females.[16] The adult males rarely groom in the groups. While not strictly territorial, guereza groups can be aggressive towards each other.[17] In some populations, groups may defend core areas, resources and mates. It is the males that participate in agonistic inter-group encounters but female may do so as well.[17] Aggressive encounters between groups usually involve chases, displays and vocalizations rather than physical contact.[17]
The guereza has a polygynous harem-based mating system.[16] Mating solicitations are done both by males and females, half of the time for each.[19] To solicit mating, a guereza will approach its partner and make low-intensity mouth clicks or tough-smacks.[20] During copulation, the males grasps the female’s ankles and trunk from behind.[21] Most copulations take place in the groups but extra-group copulations have been recorded.[21] In multi-male groups, sometimes more than one male can mate with the females.[17] The gestation period lasts 158 days with a 16-22 month interbirth interval.[9] Infants are born with pink skin and white hair. The hair darkens as they age and by 3–4 months they attain adult coloration. Male usually gain their coloration before females.[22] The newborn guereza is dependent on its mother and must cling to her. As they grow older, infants can move on their own and will actively return to their mothers.[23] The infants take up most of the attention in the groups, especially by the females. Multiple females may handle an infant although infants are uncomfortable with females that are not their mothers.[24] The males are mostly uninterested in the infants early on but their interest increases when they are 4–5 weeks.[23] Infants can eat vegetation at about 8–9 weeks and by 50 weeks they are fully weaned and no longer cling to their mothers.
The most notable vocalization of the guereza is the "roar", which is made mainly at night or dawn by males. The sound of a roar can be carried for up to a mile. Only one male in a group will roar, even in multi-male groups. Roars are used for long distance communication. When one male starts roaring, neighboring males will start to roar as well.[21] There is variation is the roars of males which could signal the status of their group and fighting ability.[21] With a roar, a male can advertise his body size; both actual and exaggerated.[25] Other vocalizations are made as well. Males may snort, possibly as an alarm call.[26] "Purrs" are made before group movements. Female and infant may "caw" when under light stress. When in strong stress, females and sub-adults will squeak or scream, particularly when infants are threatened.[26] "Tongue-clicking" is made during mild aggression.[26] In addition to vocalizations, guerezas make several different body postures and movement as well as tactile communications.
Because it can use dry and gallery forests and will travel on the ground, the guereza is among the least threatened colobine species.[7] The IUCN lists it as Least Concern because "although locally threatened in parts of its range, this widespread species is not thought to be declining fast enough to place it in a higher category of threat."[2] Unlike most other primate species, the guereza cope with habitat degradation and can thrive in degraded forests.[27] Sometimes, logging may increase the number of preferred food trees for guerezas and the monkeys are more abundant in logged areas than unlogged ones.[7] Nevertheless, complete forest clearings cause their numbers to decline as was the cause in Uganda.[28] Guerezas are also threatened by hunting/harvesting for their meat and skins. Guereza meat has been sold on the bushmeat trade for $4–9 US.[29] The guereza skins have been sold for fashion or the tourist trade.[30]