Cercopithecus ascanius
black-cheeked white-nosed monkey

Redtail monkeys (Cercopithecus ascanius) are found in Africa from the Central African Republic eastwards through Kenya and south into Angola and Zambia. Populations are most dense in Uganda. ()

Redtail monkeys can live in a rather large variety of habitats. They are mainly found in the middle canopy of tropical rain forest habitats. However, they have also been observed in swamp forests, secondary forests, riverine gallery forest, and other woodlands (Smuts et al. 1987). ()

This relatively small primate exhibits some sexual dimorphism in weight and body length. Males have an average mass of 4.1 kg and a length of approximately 46 cm. Redtail monkey females, in contrast, average 2.9 kg in mass and about 38 cm in length (Torstar Books 1984; Smuts et al. 1987).

Other than size differences, males and females of this species are very similar. The recognizable markings of adult redtail monkeys include a black face, bluish skin around the eyes, a white spot on the nose, and white cheek fur. The name 'redtail' comes from the chestnut-colored fur on the underside of the tail. The rest of the body is covered with a speckled brown coat and gray or black limbs, depending on the subspecies (Torstar Books 1984).

Redtail monkey infants have woolly gray fur at birth. Although they are born with a visible nose spot, young redtail monkeys have a brown tail and no cheek whiskers. As they mature, their markings begins to resemble those of adults (Kingdon, 1984). ()

Although data are not available for this species, other members of the genus Cercopithecus are known to live in captivity for more than 30 years. It is likely that C. ascanius is similar to other members of the genus in lifespan. Lifespan in the wild is likely to be somewhat shorter than it is in captivity. ()

This diurnal, arboreal species is quite agile and active. Their main hours of activity are in the early morning and late evening (Kingdon, 1984).

Redtail monkeys tend to be found in medium-sized groups of 11 to 14 individuals containing one male and a matrilineal group of females (Chapman and Chapman, 2000). It is common for several of these troops to congregate together at food resources or in large trees during resting periods (Kingdon, 1984). Groups of redtail monkeys travel approximately 1.4 km each day in search of food.

Allomothering, the sharing of maternal care by other females of the group other than the infant's mother, has also been observed in redtail monkey groups, although occasionally the infant is harmed in a fight for possession of the youth (Struhsaker and Leland, 1979).

Cercopithecus ascanius males, upon reaching sexual maturity, disperse from the home range and displace other males in different groups or join all-male wandering bands (Cords 1984). After displacement of the tenured male, it is common for the incumbent male to kill all existing offspring in the group, thereby making lactating females come into estrous sooner and bear his offspring (Struhsaker, 1977). ()

Home Range

Groups defend their home ranges of about 120 hectares primarily through visual threats and, if necessary, physical combat (Smuts et al., 1987). ()

As in all primates, communication in this species is complex, and includes chemical, visual, auditory, and tactile components. The visual communication system consists of eyebrow raising, facial skin stretching, and head-bobbing (Estes, 1991). These signals are commonly used to warn potential predators or unwanted intruders. Vocal communication consists of birdlike chirps between members of a group (Kingdon, 1984). This form of communication is mainly used socially among members of the same unit. These associated individuals may also identify one another by nose-to-nose greeting, in which two individuals press their muzzles together. After this greeting they will commonly practice reciprocal social grooming or play (Estes, 1991). ()

Redtail monkeys are primarily frugivorous, but supplement their diet with leaves, insects, flowers, buds, and gum (Torstar Books, 1984; Chapman and Chapman, 2000).

It is common for adults to store fruit in their large cheek pouches in order to take their meal to an area free from the threat of theft by other monkeys (Torstar Books, 1984). ()

Cercopithecus ascanius is potential prey for chimpanzees, crowned hawk-eagles, wild cats, and humans (Kingdon, 1984; Leland and Struhsaker, 1993). It is also likely that these monkeys fall victim to the same predators that trouble other small, arboreal primates in African forests. These include leopards, snakes, and a variety of avian predators. ()

Because these monkeys are frugivorous, and can transport fruits in their cheek pouches, it is likely that they play some role in seed dispersal. In addition, as a prey species, they probably have some effect on predator populations. ()

Cercopithecus ascanius regularly practices crop raiding of nearby agricultural gardens containing maize, banana, millet, bean, pumpkin, pineapple, or passion fruit crops (Kingdon, 1984). In regions of low productivity this behavior has become a serious problem for neighboring human villages.

Redtail monkeys are also one of the major carriers of yellow fever in Africa (Kingdon, 1984). When the monkeys venture into human villages to raid their crops, there is a greater chance that an infected individual could spread this disease to the villagers. ()

Redtail monkeys have been instrumental in the regeneration of Strychnos mitis, a tree species found in the Kibale Forest. Redtail monkeys feed heavily on the fruit of this tree. As they eat the fruit, they spit the intact seeds, which fall to the rainforest floor where the seeds can successfully germinate. This method of seed sowing produces more saplings annually than the fruit would normally produce without the help of redtail monkeys (Lambert 1995).

Redtail monkeys have also been useful as laboratory animals in studies on various viral diseases (Kingdon 1984).

Although redtail monkey populations are currently healthy, there is some concern about their future status. As is the case with many rainforest dwelling animals, the threat of habitat loss by deforestation is a major concern. Since C. ascanius inhabits a relatively small area on the African continent, loss of habitat could be detrimental for the future of this primate species.

Redtail monkeys are also threatened by predation. They are potential prey for chimpanzees, crowned hawk-eagles, wild cats, and humans (Kingdon, 1984; Leland and Struhsaker, 1993).

Redtail monkey populations are depleted by distraught farmers that view them as pests and shoot them on sight (Leland and Struhsaker, 1993). ()

Redtail monkeys are commonly found in close association with other primate species, such as red colobus, mangabeys, and blue monkeys. Redtail monkeys form an important feeding association with colobus monkeys. Colobus monkeys bite through the tough outer skins of Mondura fruits and redtail monkeys are able to eat the fruit scraps that contain ordinarily unobtainable fruit pulp (Leland and Struhsaker, 1993). They have also been observed to interact socially with other species; playing, grooming, and helping in defense from common predators.

Redtail monkeys have been observed to mate with blue monkeys, and produce fertile offspring (Leland and Struhsaker, 1993). ()