Procolobus verusolive colobus

Geographic Range

Procolobus verus is found on the western coast of Africa, from Sierra Leone to Tongo. There is also an isolated population in eastern Nigeria.

(Burton and Pearson, 1988; Oates and Whitesides, 1990; Flannery, 2000; Nowak, 1997) (Burton and Pearson, 1988; Flannery, 2000; Nowak, 1997; Oates and Whitesides, 1990)


Olive colobus monkeys are arboreal and are restricted to rainforest habitat. They prefer the dense understory of the forest, often near water. Procolobus verus sometimes travels into the middle canopy to sleep, but never ventures to the upper stratum.

(Burton and Pearson, 1988; Flannery, 2000; Nowak, 1997) (Burton and Pearson, 1988; Flannery, 2000; Nowak, 1997)

Physical Description

Procolobus verus is the smallest and the most drab colored of all African colobus monkeys, bearing olive colored hair with a tinge of brown on top and grayish underparts. Weights range from 2 to 4.5 kg, and body lengths of 90 to 430 mm are reported. Procolobus verus has a similar body structure to black and white colobus monkeys, but olive colobus monkeys have a small crest on top of the head and the most reduced thumb and largest feet of any colobine. Males are equal in size to females with relatively larger canines than females.

Procolobus verus possesses six cusps on the lower third molars.

(Burton and Pearson, 1988; Nowak, 1997) (Burton and Pearson, 1988; Nowak, 1997)

  • Sexual Dimorphism
  • sexes alike
  • Range mass
    2.2 to 4.5 kg
    4.85 to 9.91 lb
  • Range length
    90 to 430 mm
    3.54 to 16.93 in


These colobines are reported to be polygynous.

Olive colobus monkeys have a gestation period of 5 to 6 months, with no specific breeding season. Females reproduce about every two years and usually bear only one young at a time. Females reach sexual maturity around 3 to 4 years old, males around 5 to 6 years old. Female P. verus have perineal organs that swell during estrus. (Flannery, 2000)

  • Breeding interval
    Females can produce young once every 2 years.
  • Breeding season
    Breeding in this species occurs throughout the year.
  • Average number of offspring
  • Range gestation period
    5 to 6 months
  • Range age at sexual or reproductive maturity (female)
    3 to 4 years
  • Range age at sexual or reproductive maturity (male)
    5 to 6 years

Female P. verus carry their young around in their mouths for a few weeks after birth, a behavior not observed in Colobus species. As the young matures, it is carried on the abdomen of the mother. Mothers provide milk, grooming and protection for the young. The role of males in care of infants has not been reported.

  • 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
  • extended period of juvenile learning


The lifespan of these animals has not been reported, but other leaf eating monkeys rarely live in excess of 30 years in captivity. It is likely that P. verus is similar. (Nowak, 1997; Nowak, 1997)

  • Average lifespan
    Status: wild
    20 years
  • Average lifespan
    Status: captivity
    29 years


Procolobus verus is diurnal and uses quadrapedal locomotion. Troops of P. verus consist of an old male, several females and their offspring. Group size ranges from 10 to 15 individuals. This species is often seen grouping with other monkeys, especially Diana monkeys. When an alarm call is sounded, usually by a Diana monkey, P. verus sits very still, camouflaged by the green color of its pelage.

(Burton and Pearson, 1988; Oates and Whitesides, 1990; Flannery, 2000; Noe and Bshary) (Burton and Pearson, 1988; Flannery, 2000; Oates and Whitesides, 1990)

Communication and Perception

Communication in these monkeys is not well described. However, we may assume that they are like other primates, and use various means of communication. Included in these are visual signals, such as facial expressions and body postures, vocalizations, and tactile communication, including grooming, playing, and aggression. (Nowak, 1997)

Food Habits

Procolobus verus forage in understory and middle canopy of the forest, feeding mainly on young leaves. These monkeys are highly selective feeder, but seasonally they will also eat seeds, flowers, and petioles. When young foliage is available, they ignore mature leaves. Procolobus verus has a sacculated stomach to assist in the breakdown of cellulose in its primarily folivorous diet.

(Flannery, 2000; Oates, 1988) (Flannery, 2000; Oates, 1988)

  • Plant Foods
  • leaves
  • seeds, grains, and nuts
  • flowers


Procolobus verus is the most accomplished leaper in the Tai Forest, where it commonly lives. This capability of P. verus allows it to avoid predators that share this habitat. It also frequently groups with Diana monkeys to avoid predation. Procolobus verus is hunted by humans for its meat and skin.

(Noe and Bshary)

Ecosystem Roles

The ecosystem role of these animals is not well understood. We may assume that to the extent that other animals prey upon these monkeys, they serve as a control on predator populations. They may also help to disperse seeds.

Economic Importance for Humans: Positive

Procoloby verus is hunted by humans for food.

  • Positive Impacts
  • food

Economic Importance for Humans: Negative

There are no known adverse effects of P. verus on humans. However, as primates, they may carry some of the same disease organisms which affect people.

Conservation Status

Although this species is not of special conservation concern, all primates are listed as CITES appendix II because they are vulnerable to habitat loss.


Nancy Shefferly (editor), Animal Diversity Web.

Leah Thompson (author), University of Michigan-Ann Arbor, Kate Teeter (editor), University of Michigan-Ann Arbor.



living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

World Map


uses sound to communicate


young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.


Referring to an animal that lives in trees; tree-climbing.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.


uses smells or other chemicals to communicate

  1. active during the day, 2. lasting for one day.

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.


union of egg and spermatozoan


an animal that mainly eats leaves.


A substance that provides both nutrients and energy to a living thing.


An animal that eats mainly plants or parts of plants.


offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).


having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.


having more than one female as a mate at one time


rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.


remains in the same area


reproduction that includes combining the genetic contribution of two individuals, a male and a female


associates with others of its species; forms social groups.


uses touch to communicate


Living on the ground.


the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.


uses sight to communicate


reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

year-round breeding

breeding takes place throughout the year


Burton, J., B. Pearson. 1988. The Collins Guide to the Rare Mammals fo the World. Lexington, Massachusetts: The Stephen Greene Press.

Flannery, S. 2000. Accessed September 23, 2001 at

Noe, R., R. Bshary. "Association of red and olive colobus monkeys with diana monkeys" (On-line). Accessed 11/14/2001 at

Nowak, R. 1997. "Walker's Mammals of the World/Olive Colobus Monkey" (On-line). Accessed November 12, 2001 at

Oates, J. 1988. The diet of the olive colobus monkey, *Procolobus verus*, in Sierra Leone. International Journal of Primatology, 9/5: 457-478.

Oates, J., G. Whitesides. 1990. Association between Olive Colobus, *Procolobus verus*, Diana guenons, *Cercopithecus diana*, and other Forest Monkeys in Sierra Leone.. American Journal of Primatology, 21/2: 129-146.