Piliocolobus preussi

Geographic Distribution and Habitat

The Preuss’s red colobus (Piliocolobus preussi) is an African monkey native to western Cameroon and a small section of southeastern Nigeria. They make their homes among high canopies in dense rainforests, and they spend the majority of their time in the upper canopy.

Because of illegal hunting and severe threats to their habitats, Preuss’s red colobus is one of the most critically endangered primate species in the world.

Before their significant population decline, Preuss’s red colobus monkeys inhabited a much larger area in the western part of Africa. Today, the majority of the population lives in Cameroon in Korup National Park. There’s also a small community close to the border of Cameroon, in Nigeria’s Cross River National Park.

Preuss's red colobus range, IUCN 2017

Size, Weight, and Lifespan

Compared to other red colobuses, the Preuss’s red colobus is considered large-bodied. Individuals weigh an average of 11–24.25 pounds (5–11 kg), which is comparable to a large housecat. From head to body, average lengths are 22–24 inches (56–63 cm), and their tails add about 29.5 inches (75 cm).


As the name suggests, Preuss’s red colobuses have varying shades of red fur on their bodies and tails. Their chest, belly, and inner limbs are cream-colored, and their backs are red and black. Around their dark faces are orange cheeks. Infants are black with gray undersides.

The Preuss’s red colobus has denser and frizzier fur than similar species.

Because they live in dense forest, there are few photos of Preuss's red colobus. This is the closely related western red colobus, Piliocolobus badius.

Like other species of red colobuses, Preuss’s red colobus monkeys are folivores (leaf eaters). They prefer the young leaves from a variety of different trees. They also supplement their diet by snacking on flowers and buds.

Since immature leaves are low in nutrition, they have to eat a lot to survive. The high volume of leaves they eat subsequently plays an integral role in how the forest ecosystem is structured. Most often, Preuss’s red colobuses feed from trees that are exploited for timber, which affects both their nutrition options and their habitats.

Behavior and Lifestyle

​Preuss’s red colobus monkeys are arboreal and spend most of their time in the upper canopy of their rainforest homes. In fact, colobus monkeys are the most arboreal of the African monkeys. They rarely visit the forest floor.

Like many other leaf-eaters, ​Preuss’s red colobus monkeys are slow-moving and spend a lot of their day resting. They socialize by grooming others in their large group, which can include anywhere between 20 to 60 individuals.

Fun Facts

The Preuss’s red colobus is one of 18 different species of red colobus monkeys.

“Colobus” comes from the Greek word for “mutilated.” They got this name because colobus monkeys do not have thumbs.

Daily Life and Group Dynamics

In Korup National Park in Cameroon, group sizes range between 20 to 60 individuals. Groups of over 100 individuals have also been reported. The size of the group is likely dependent on the quality of the habitat, predation, and other threats.

The average group of Preuss’s red colobus monkeys includes multiple males and females and their young. Typically, groups will contain more adult females than adult males.

Dispersal patterns are not known in the Preuss’s red colobus, but in other species of red colobus monkeys, both males and females disperse from their natal group. However, many males stay in their natal groups and form coalitions with other males.


Little is known about Preuss’s red colobus communication, but there have been several accounts of red colobuses with complex vocal repertoires.

These accounts tell us that red colobuses may use various chirps, barks, and yelps in low to high pitches. They will also make aggressive sounds when threatened by predators or other groups of colobus monkeys. Males seem to be the primary talkers, but females are more vocal when mating.

Reproduction and Family

There is limited information on Preuss’s red colobus reproduction, but they may be similar to other red colobus monkeys.

Female red colobuses give birth to one child every two years, after a gestation period of 5 to 6 months. Births occur all throughout the year, but mating peaks during the rainy season.

Adult females approaching estrus display swelling and bright red coloring on the genital area, which is a visual way to communicate her reproductive status and readiness to mate. They also leap and make loud calls to alert males.

Facing Korup National Park, home to a majority of extant Preuss's red colobus monkeys. Photo credit: Christos Astaras/Creative Commons
Ecological Role

The Preuss’s red colobus plays two important ecological roles. Their leaf-heavy diet makes them an important part of structuring their forest ecosystems. And they are also vulnerable to predation by chimpanzees in areas where they have overlapping ranges.

Conservation Status and Threats

The Preuss’s red colobus is listed as Critically Endangered by the International Union for Conservation of Nature (IUCN, 2019). The species was listed in the IUCN SSC Primate Specialist Group’s “Primates in Peril: The World’s 25 Most Endangered Primate Species February 14, 2016” report.

The Preuss’s red colobus has been classified as Critically Endangered since 2008 and is the most endangered species of African monkeys. Their population decreased by over 80% in the last three generations (30 years) and it continues to decline.

Humans are the biggest threat to the Preuss’s red colobus. Throughout Cameroon and Nigeria, their habitats are threatened by illegal hunting and habitat loss. The trees where they make their homes are threatened by both small and large-scale industrial agriculture. There are also high levels of illegal hunting in the area.

Conservation Efforts

Since humans are the biggest threat to Preuss’s red colobus monkeys, education is crucial to conservation. In Cameroon, The Mohamed bin Zayed Species Conservation Fund is working to increase conservation knowledge through rural and urban conservation outreach programming. Their mission is to educate communities about the fragility of ecosystems and the urgent need to conserve the habitats where Preuss’s red colobus monkeys and other wildlife call home.

The Red Colobus Action Plan (ReCAP)—the first action plan to target an entire group of African monkeys—was presented at the 2018 International Primatological Society Congress in Kenya. ReCAP is a joint effort of the IUCN/SSC Primate Specialist Group and the African Primatological Society. The plan’s goal is to unite and mobilize conservation groups, communities, governments, zoos and wildlife centers, and other institutions to help protect red colobuses from extinction.

While these conservation groups are integral to the survival of Preuss’s red colobus monkeys, there is no such group solely dedicated to saving the species. More research is needed to get a more accurate estimate of the remaining population and to better understand the behavior of this species.


Written by Maria DiCesare, July 2023