Cercopithecus wolfi
Wolf's monkey

Cercopithecus wolfi is most commonly found in the Democratic Republic of Congo and areas in Uganda. There are three subspecies of Wolf’s monkey: Cercopithecus wolfi wolfi occurs between the Congo and Sankuru Rivers, Cercopithecus wolfi pyrogaster is found between the Kwango and Kasai-Lulua Rivers, and Cercopithecus wolfi elegans is found between the Lomami and Lualaba Rivers. (Groves, 2001)

Cercopithecus wolfi occupies primary and secondary lowland rainforest habitats. Wolf's monkeys are commonly found in swamp forests and secondary forests along riverbanks. They spend a majority of their time between 15 and 25 meters high in the canopy where they forage and sleep. (Groves, 2001; Napier and Napier, 1967; Rowe, 1996)

Wolf's monkeys have dark grey fur dorsally with a reddish patch in the center of the back. The ventral fur is usually white or pale yellow. The forelimbs are dark grey to black while the hindlimbs are a light reddish-brown color. The distal half of the tail is black while the proximal half is a grayish coloration. The face is characterized by a black patch extending from ear to ear, from below the eyes to the top of the head. Within this black area is a patch of white fur that grows from the brow. The cheeks and chin are the same whitish-yellow as the ventral fur and the ear tufts are often white or slightly reddish. The scrotum is blue, which may be important in mate selection. Blue scrotal color is common in many Cercopithecus species and related genera. Wolf's monkeys have ischial callosities (callus-like areas of skin on the buttocks). This provides a degree of comfort while sitting on branches and night resting. These callosities are typical of the family Cercopithecidae. ("Wildlife Conservation Society", 2007; Fleagle, 1999; Napier and Napier, 1967; Rowe, 1996)

Being an arboreal quadruped, Wolf's monkeys have forelimbs and hindlimbs that are fairly equal in length giving it an intermembral index number close to 100. The head and body length of males varies from 445 to 511 mm with an average of 485 mm. The length of the tail in males ranges from 695 to 822 mm with an average of 779 mm. There has not been enough data collected from females to adaquetely determine these measurements. Cercopithecus wolfi is a sexually dimorphic species. The weight of males ranges from 3.8 to 4.2 kg, females are considerably smaller, ranging from 2.4 to 3.1 kg. Males also have larger canine teeth than females.

The average lifespan is reported to be 20 to 26 years. ("Wildlife Conservation Society", 2007)

Cercopithecus wolfi is a diurnal species with an arboreal quadrupedal style of locomotion. They tend to reside and forage at an average height of 15 meters above the ground. Wolf's monkeys are most active in the morning and evening.

Wolf’s monkeys live in single-male, multi-female groups. Post adolescent males leave their natal group and form bachelor groups. These bachelors will occasionally try to overtake the dominant male of another group and gain reproductive rights to the females. Females stay in their natal group.

Group size varies from 1 to 12 individuals. Larger groups will often split into smaller foraging groups while searching for patchy foods such as fruits and insects. These monkeys are also found in mixed-species groups. They are most often seen associating with black mangabeys (Lophocebus aterrimus), about 80% of the time. Less often they are seen with red-tailed guenons (Cercopithecus ascanius) and Angolan black-and-white colobus monkeys (Colobus angolensis). (Fleagle, 1999; Nowak, 1999; Rowe, 1996)

Home Range

There is currently not enough data about the size of day ranges and home ranges of C. wolfi. Both females and males have been observed actively defending territories, but it is unclear what the boundaries and size of these territories are. Home ranges in other Cercopithecus species vary widely, from 3 to 130 hectares. (Fleagle, 1999)

Vocalizations of Wolf’s monkeys includes 2 contact calls, 2 travel calls, and 3 alarm calls. The most common contact call is used while foraging. These monkeys let out an occasional grunting sound to maintain vocal contact and know the positions of other members of the group. These calls are made more often when foraging in large groups or in areas of low visibility, such as the upper areas of the canopy. Vocal communication is also more common while hunting for insects than foraging for fruits and leaves. To communicate territoriality, males let out a boom call, which is a low, short tone that can be carried long distances due to resonating air sacs. A common alarm call is the sneeze call. It is a short call resembling a the sound of a sneeze.

This species also uses visual communication to convey threats and aggression. Males fix their eyes on the target, move back their ears to stretch out the facial skin, and retract their scalp. This is called staring. Along with staring, they will sometimes open their mouths, but keep the teeth hidden. To present an even greater threat, they will stare with their mouth open, but begin bobbing their head. A fear grimace is used as an appeasement signal to reduce aggression in aggressive encounters. This is accomplished by retracting the lips to show the teeth, but keeping the teeth closed together. Males also perform a visual cue that resembles yawning. The mouth is opened and the canines are revealed to convey tension or aggression.

Like other primates, Wolf's monkeys also extensively use grooming for tactile social communication. The use of chemical cues, such as pheromones, is likely, but undocumented. (Estes, 1991; Mulavwa, 1991; Rowe, 1996)

Wolf's monkeys are frugivorous, but they supplement their diet heavily with leaves, seeds, and flowers. At Salonga National Park in the Democratic Republic of Congo, Wolf's monkeys have been recorded consuming 32% fruit (4% fleshy and 27% arils), 27% seeds, 29% leaves, and 11% flowers. Though not a primary means of sustenance, Wolf’s monkeys will occasionally feed on nectars and insects if they are readily available. The principal feeding time for this species is during the early morning and early afternoon. (Lambert et al., 2002; Napier and Napier, 1967)

Since this species is arboreal, its main predators are avian, primarily crowned hawk eagles (Stephanoaetus coronatus). When these birds are spotted by Wolf's monkeys, they will sound an alarm call and retreat to the ground. Though less common, leopards also pose a threat to this species. More recently, humans have become a major predator of this species for the bush meat market. In addition, their primary habitat is being destroyed at an extremely rapid pace for lumber. ("Wildlife Conservation Society", 2007; Rowe, 1996)

Wolf's monkeys are probably important in seed dispersal of food trees and they may contribute to pollination when they drink nectar.

Wolf's monkeys occasionally raid local agricultural crops and have a potential for carrying diseases that can be contagious to humans.

Wolf's monkeys are one of the species hunted in the bushmeat market. Their meat provides food to local inhabitants and a product to trade for other goods. They are also likely to play a role in the regeneration of healthy forests through seed dispersal.

Cercopithecus wolfi has not been evaluated by the IUCN. As a primate, C. wolfi is on appendix II in CITES.