Despite being widespread, De Brazza's monkey is generally shy and inconspicuous, only rarely announcing its presence with deep, booming group calls (1) (5). This species is mostly arboreal, but unlike other guenons, which usually stay in the tree canopy, it is often found moving through the forest understory or along the ground (6). The diet consists mainly of fruits and seeds, although leaves, mushrooms and small reptiles and insects may also be consumed (4) (5). As foraging usually takes place in exposed areas, food is stored in cheek pouches, and only eaten when the monkeys return to a safe location (4). Throughout much of its range, this species lives in polygynous groups of between eight and ten individuals, but in certain regions, such as Gabon, De Brazza's monkeys can be found in small, monogamous family groups, comprising a male-female pair and their offspring (2) (6). Interestingly, De Brazza's monkey is the only guenon species that forms these strong breeding pair bonds (5). Although groups maintain small territories that they mark out with saliva and scent, they do not appear to show any aggression towards other groups of De Brazza's monkey that enter these areas (4) (5). In contrast, when encroachment is made by a different species of monkey, De Brazza's monkeys may become extremely hostile, with the entire group becoming involved in forcibly ejecting the intruder (4). De Brazza's monkey breeds throughout the year, with the female usually giving birth to a single infant after a gestation period of around 168 to 187 days. In order to reduce the risk of predation, the vulnerable infant clings tightly to the mother's stomach. Weaning takes place after around one year, but the young begin to try solid food after about two months of age. De Brazza's monkeys become sexually mature at around age five or six, and may live for up to 22 years in the wild (4). De Brazza's monkey is preyed upon by numerous animals, such as large African eagles, leopards, and other primates—including humans (7). When a group is threatened, the females and the young generally hide in the undergrowth, while the male climbs a tree and makes loud calls in an attempt to distract the predator (6).

De Brazza's monkey is one of the most distinctive species of guenon, a collective name for members of a large group of African monkeys belonging to the genus Cercopithecus (4). The head is adorned with a striking orange-red crescent shaped patch on the brow, and the face has a white muzzle extending into a long, white beard. The coat is mostly finely speckled grey and white, with black limbs and tail. Other distinguishing features include a white thigh stripe and rump and, in the male, a bright blue scrotum (2) (4).

This widespread species ranges from north-eastern Angola, Cameroon, Equatorial Guinea (Rio Muni) and Gabon in the west of its range to Uganda, Kenya and south-western Ethiopia in the east. It was formerly believed that the Sanaga River formed the northern boundary in Cameroon, but Maisels et al. (2007) extended the current known range for C. neglectus 100 km farther north in Cameroon, about 140 km farther south in Gabon, and about 80 km farther west in Congo than was previously known. The surveys were carried out in Cameroon in the Mbam Djerem National Park, in Gabon in the Bateke Plateau National Park, and the adjoining Bateke Plateau area in Congo. C. neglectus were found on both sides of the Djerem River in Cameroon, along the Mpassa and its tributaries in Gabon, along the Nambouli River in the Lefini Reserve in Congo, and up to the right bank of the Ogooué River on the Congo side of the border (Maisles et al. 2007). Until recently, the species was not known to range east of the Great Rift valley in Kenya, but it has now been recorded in the remote and isolated Mathews Range Forest Reserve of Samburu at an elevation of 2,200 m (the highest elevation at which the species has yet been recorded; Mwenja 2007).

The range of Debrazza's monkey, Cercopithecus neglectus, is a large triangle bordered by southern Ethiopia to the Northeast, Cameroon to the Northwest, and northern Angola to the south. This species is more common in easten Africa and less regularly observed on the continent's western side.

Biogeographic Regions: ethiopian (Native )

One of the most widespread guenon species, the range of De Brazza's monkey extends from Cameroon, southwards, through northern Gabon, and Congo to northern Angola, and eastwards through much of the Democratic Republic of Congo and southern Central African Republic to eastern Uganda. Fragmented populations are also found in western Ethiopia, extreme southern Sudan and eastern Kenya (1).

This species shows marked sexual dimorphism in size. Male Debrazza's monkeys weigh up to 7 kg, three more than the average female, which weighs 4 kg. Lengths range from 40 to 63.5 cm. Females and males are gray with black extremities and tail. The shape of the head is round, with a long white beard, white muzzle, and an orange crown. The thighs and rumps have white stripes. Legs are long, and the tail is non-prehensile.

Male Debrazza's monkeys have a distinct blue scrotum. In addition, both males and females have well-developed cheek pouches and the most robust feet of all of the guenons.

Range mass: 4 to 7 kg.

Range length: 40 to 63.5 cm.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry

Sexual Dimorphism: male larger

Habitat and Ecology

Systems

• Terrestrial

Debrazza's monkeys are found in forests, swamps, and seasonally flooded areas. They exist predominantly in the closed canopy, preferring dense vegetation, and are generally found within 1 km (.62 miles) of rivers in humid forests.

Habitat Regions: tropical ; terrestrial

Terrestrial Biomes: forest ; rainforest

De Brazza's monkey generally occupies forested regions close to rivers and waterways, including dense swamp forest, lowland tropical forest, and mountain forest up to elevations of 2,200 metres (1) (2).

Debrazza's monkeys are omnivorous, but primarily eat fruit. Other items in their diet include leaves, flowers, mushrooms, beetles, termites, and worms.

Animal Foods: insects; terrestrial worms

Plant Foods: leaves; fruit; flowers

Other Foods: fungus

Primary Diet: omnivore

As a prey species, it is likely that these small primates have some impact on predator populations. In addition, because they are largely frugivorous, they probably play some role in seed dispersal.

Ecosystem Impact: disperses seeds

Like other small forest monkeys, it is likely that Debrazza's monkeys fall prey to chimpanzees, leopards, various avian predators, and snakes.

Communication between Debrazza's monkeys is both vocal and visual. Visual communication includes staring as a threat, sometimes with the mouth open but the lips covering the teeth. Another threat display is bobbing the head up and down. To reduce aggression in certain situations the lips are retracted showing clenched teeth. As an expression of tension or as another threat display, yawning by adult males is performed to show the canines.

Vocal communication consists of low boom calls to communicate territorialiy, and isolation calls often given by infant or juvenile monkeys when they become separated from the troop.

In addition to these, there is communication through tactile signals. These are likely to be especially important during mating, as well as between mothers and their offspring.

Communication Channels: visual ; tactile ; acoustic ; chemical

Perception Channels: visual ; acoustic

The longevity of C. neglectus has not been reported, but other species within the genus Cercopithecus have been reported to live in excess of 30 years in captivity. Lifespans in the wild are likely to be somewhat shorter. It is reasonable to assume that Debrazza's monkeys are like the other members of their genus in regard to lifespan.

Average lifespan

Status: captivity: 30 years.

Average lifespan

Sex: female

Status: captivity: 23.0 years.

Average lifespan

Sex: female

Status: captivity: 26.3 years.

Maximum longevity: 30.8 years (captivity)

The sexual dimporphism in size of this species suggests that breeding is probably polygynous. In most guenons, females remain in their natal group all of their lives, whereas males disperse around the time they reach sexual maturity. Males typically compete to control access to a group of females (Nowak, 1999). However, this species is reported to sometimes be found in pairs with young, indicating that there may be some monogamy (Oregon Zoo, 2005).

When it is time to mate, females solicit copulation by presenting themselves. During copulation, the female pouts by sticking her lower lip forward while keeping her lips closed.

Mating System: polygynous

Debrazza's monkeys reach sexual maturity at 5 to 6 years of age. The breedng interval is long, but the gestation period is 5 to 6 months. Single births are normal, although twins are produced on rare occasions. The known breeding season in the equatorial rain forest is from February to March. Otherwise, breeding occurs when food is available.

Becuase females nurse their young for a year, it is unlikey that females are able to produce more than one young per year, even under good conditions. Young begin to eat solid food around the age of 2 months.

Breeding interval: The exact breeding interval is not known.

Breeding season: The known breeding season in the equatorial rain forest is from February to March.

Range number of offspring: 1 to 2.

Range gestation period: 5 to 6 months.

Average weaning age: 12 months.

Range age at sexual or reproductive maturity (female): 5 to 6 years.

Range age at sexual or reproductive maturity (male): 5 to 6 years.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); viviparous

Average birth mass: 260 g.

Average number of offspring: 1.

When born, the young are furred with eyes open. Newborns are able to cling to their mother's fur, but are comletely dependent upon her for food, comfort, grooming, and protection. Females nurse and care for their young until they become independent, sometime around the age of 1 year. Young females stay with their mothers a long as they live, whereas males leave when they are sexually mature.

The role of males in parental care has not been described. Although most parental care is clearly the responsibility of the mother, fathers may aid in protecting the young born to them in the social group from predators or from infanticidal males. Although infanticide has not been reported for this species, it does occur in other guenons.

Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Provisioning: Female, Protecting: Female); post-independence association with parents; extended period of juvenile learning

Debrazza's monkeys are neither endangered nor threatened. However, in 1975, Ethiopia started protecting them from being hunted and trapped. Threats to these monkeys include the pet trade, habitat destruction from deforestation, range fragmentation from increasing human populations, and cultivation, mainly of coffee plantations in Ethiopia. These monkeys can also be found protected on the Dja Reserve in Cameroon.

US Federal List: no special status

CITES: appendix ii

IUCN Red List of Threatened Species: least concern

Classified as Least Concern (LC) on the IUCN Red List (1) and listed on Appendix II of CITES (3).

Population

Population Trend

Major Threats

Although De Brazza's monkey is widespread, it is never found in abundance in any part of its range, and in many regions appears to be undergoing a decline. The main threat to this species is habitat loss due to ongoing forest clearance for agriculture and timber (1). In addition, De Brazza's monkey is also hunted for food, and may become increasingly targeted due to the expansion of the bushmeat trade (1) (4).

Conservation Actions

De Brazza's monkey occurs in a number of protected areas across its range, thereby safeguarding, to some extent, against habitat loss (1). The recent discovery of this species in the Lesio-Louna and south-west Lefini Reserves in the Democratic Republic of Congo, has shown that conservation activities targeted towards reintroducing gorillas to the region have also helped the local De Brazza's monkey population to recover from years of heavy hunting (8). De Brazza's monkey is listed on Appendix II of the Convention on International Trade in Endangered Species (CITES), and therefore any international trade is strictly controlled through maximum export quotas (3). In addition, in many African countries, hunting of this species requires authorisation (1) (9), while in Ethiopia it is prohibited altogether (7). Despite these controls, the bushmeat trade for De Brazza's monkey—along with many other species—continues to grow (4). In order to combat this, a consortium of conservation organisations called the Bushmeat Crisis Task Force has been established. By working with governments, organisations and the general public, they aim to eliminate unsustainable and illegal bushmeat hunting practices worldwide (10).

There are no negative effects of Debrazza's monkeys on human economies.

Debrazza's monkeys are hunted for their flesh in Zaire and Cameroon. They have also been widely collected for zoos, mainly from areas of Uganda and Kenya. From 1968 to 1973, 152 Debrazza's monkeys were imported into the United States and from 1965 to 1975, 373 were imported into the British Isles.

Positive Impacts: pet trade ; food ; research and education