Black Colobus, Colobus satanas
BLACK COLOBUS
Colobus satanas
Geographic Distribution and Habitat
The black colobus (Colobus satanas), also known as the satanic black colobus or black colobus, is an Afro-Eurasian monkey that inhabits small regions of western central Africa.
This species can be found in Equatorial Guinea, southwest Cameroon, and central and northwestern Gabon, with smaller populations in the north of the Republic of Congo. Here, they roam the lush rainforests and can occasionally be found near coastal areas and in wooded meadows.
The stability of their environment is of vital importance because they struggle to survive in secondary forests, which are forests that have been replanted due to deforestation. They generally avoid human settlements; thus, habitat disruption is taking its toll on them.
Two subspecies of black colobus are currently recognized: the Bioko black colobus (Colobus satanas satanas) on Bioko Island, and the Gabon black colobus (Colobus satanas anthracinus), found in Gabon
Size, Weight, and Lifespan
The black colobus is a relatively large monkey. Head-body length is around 19-27 inches (50–70 cm), with a tail as long as 31 inches (80 cm). There are no significant differences between the two sexes, except that males may grow larger on average. Males can weigh between 22-33 pounds (10–15 kg), while females usually weigh between 10-11 pounds (4.5–5 kg).
We don’t know exactly how long they live in the wild because this species is rather skittish and lives high in the canopy. They also struggle to reproduce in captivity, making life-long studies rather difficult. However, most colobine species live around 20 years.
Appearance
Black colobus monkeys owe their name to their distinctive pitch-black fur that covers almost the entirety of their body. This species may well be considered a gothic icon. Their fur has a smooth appearance and tends to spike up on their head. Their skin, exposed on their hands, feet, and face, is also black.
They have slender and agile bodies, with longer patches of fur covering their thin limbs. Their tail is long and relatively thick considering how thin their bodies are. Their eyes are also piercingly black.
Babies are born with brown fur that later develops into the characteristic black fur of adults.
Diet
The black colobus monkey is herbivorous, feeding exclusively on plant matter. Although they love munching on leaves, buds, and unripe fruit, their diet mainly consists of seeds. In some periods, as much as 60% of their monthly feeding is made up of seeds.
Unlike other primates, colobus monkeys have multi-chambered stomachs that allow them to digest leaves more easily. Their digestion is often described as ruminant-like because it resembles that of ruminants, like cows, sheep, and goats, all species that predigest food by fermenting it in specialized stomach chambers. Colobine monkeys have two stomach portions: one with a neutral pH filled with bacteria evolved to digest cellulose where food is fermented and predigested, and the other with an acidic pH where digestion is completed. Because of this formidable evolutionary advantage, they’re able to feed on leaves that many other animals don’t find palatable.
Whereas most colobus species prefer to feast on young leaves packed with nutrients, black colobus monkeys can withstand higher concentrations of plant toxins found in immature leaves, giving them a significant advantage over other species. This ability cuts down their competition and allows them to live in areas unoccupied by other species.
Interestingly, black colobus monkeys have also been observed eating soil, probably as a supplementary source of sodium.
Behavior and Lifestyle
The black colobus monkey is an arboreal and diurnal animal, meaning they spend most of their life in trees and are active during the day while resting at night. They spend 22% of their day eating, which includes plucking, handling, and finally ingesting food.
Although they’re exclusively active during the day, the majority of it is spent in idleness. They sleep in trees, like the azobé tree, and there they rest until mid-morning. After waking up, they laze around a little bit; they sit and enjoy the safety of their tree, groom, and occasionally feed if the tree bears any food. When the sun starts getting a little too hot, they move down to laze some more. It’s only in the mid-afternoon that the show goes on: their feeding feast begins then. It’s during this time that they move around their home range the most. By evening, they return to higher spots to settle down for the night. Because they feed on leaves and plant matter that’s difficult to digest, their activity level is quite low.
The trees they feed on tend to grow quite fast, so it is not unusual for this species to feed on the same trees in rotation. They’re extremely skilled leapers, as they often use branches and lianas as launching pads to spring from one tree to another. They also move on their four limbs. Natural predators of this species include leopards, Panthera pardus, and crowned eagles, Stephanoaetus coronatus.
The word ‘colobus’ is a Greek word meaning ‘mutilated.’ This name refers to the fact that over time these monkeys have evolved and lost their thumb.
Unlike most colobine monkeys, the black colobus monkey prefers seeds over leaves.
They have multi-chambered stomachs that resemble more those of cows than those of other primates.
Black colobus monkeys are gregarious animals living in groups of about 15 individuals, although group size varies significantly. They live in multi-male groups in home ranges that extend beyond 1,400 acres (around 573 ha). This species is rather territorial; however, parts of their home range overlap with those of neighboring groups, and only a fraction of their home range is used exclusively by one troop. This is also why estimating the exact number of monkeys belonging to a single group is an arduous task. It’s been suggested that this species is semi-nomadic, meaning they migrate to different places depending on food availability and don’t feel shackled to specific areas.
Not only do black colobus monkeys share their home range with neighboring groups, but they coexist with a multitude of other species, including other primates such as mangabeys and crested mona monkeys (Cercopithecus pogonias). When other fruit- or seed-eating species are present, black colobus monkeys tend to feed more on leaves. But they don’t just coexist with some species; they interact with them. Male crested mona monkeys sometimes join black colobus groups and become integral parts of their troop. Interspecies interactions between the two species are rather common, for example, through grooming. Crested mona monkeys are usually silent creatures, but those who join black colobuses find their voice and help black colobus monkeys escape predators by launching alarm calls.
The black colobus monkey relies on vocal communication to maintain contact with other members of their group and to warn others against predators. Additionally, they use alarm calls to deter neighboring groups and ensure that they don’t trespass. Finally, they are responsive to alarm calls of other species, like the previously mentioned crested mona monkeys.
Grooming is also an essential communication tool, used to establish and maintain friendships and strengthen group cohesion.
This species does not have a specific breeding season, although they prefer mating during wetter periods. Females become fertile around the age of 4, while males reach sexual maturity around 6.
A female black colobus monkey generally gives birth to one baby, which is born helpless and depends completely on the support of their mother. As a matter of fact, other members of the group rarely take care of babies that are not directly related to them, and male black colobus monkeys take little to no interest in their offspring.
The black colobus monkey plays an essential role as a pruner and seed disperser. This species feeds mostly on seeds, aiding their dispersal in the environment. Moreover, they feed on leaves, contributing to healthier forest growth. The trees they feed on are fast-growing, and without proper control, they would take over the entire forest. Black colobus’s feeding habits provide the necessary counterbalance, ensuring better biodiversity. Moreover, this species lives in the upper canopy of forests. Their movements, foraging, and living habits help shape the canopy structure.
Needless to say, black colobus monkeys live in harmony with a myriad of species. Their disappearance has long-lasting effects on other animals that share the same ecosystem.
The black colobus is classified as Vulnerable by the International Union for Conservation of Nature (IUCN, 2019), appearing on the IUCN Red List of Threatened Species. In the past 30 years, the number of black colobuses has declined dramatically, mainly due to illegal hunting. This species is relatively slow and easy to target, and due to their size, their meat is highly prized. As a matter of fact, their meat is consumed locally and sold in nearby cities. Other threats include habitat loss due to urbanization, agriculture, and the pet trade. In many areas, urban settlements are rapidly expanding. Roads have been constructed through the once remote forest floors, making previously isolated locations easily accessible by hunters, thus increasing hunting and facilitating transport. In Cameroon and Equatorial Guinea, forests are being cut down to make space for farms, destroying their homes.
Finally, mining and quarrying also contribute to habitat destruction. It is estimated that around 30% of black colobuses have already disappeared. The subspecies Bioko black colobus is even more at risk, considering the limited size of their home range.
The future looks pretty grim as populations keep disappearing due to human activity. If we don’t put a stop to it, we risk losing them forever.
Black colobuses are listed in Appendix II of the Convention on International Trade in Endangered Species (CITES), an international agreement between governments whose goal is to ensure that international trade in specimens of wild animals and plants does not threaten their survival. They occur in many protected areas, including a World Heritage Site, Lopé (Gabon). It is in protected areas that the black colobus is thriving since they’re slowly disappearing in other parts. For example, the subspecies Bioko black colobus is almost entirely found in protected forests as they’ve been wiped out in other parts.
Equatorial Guinea banned hunting, trade, and consumption of primates in 2007; however, it seems that the law is often bent or simply ignored. Finally, in Congo, it is considered a completely protected species. Nevertheless, their name makes no appearance in any laws of the other three range states.
Worth mentioning is The Bioko Biodiversity Protection Program born from the collaboration between Drexel University in Philadelphia, USA, Universidad Nacional de Guinea Ecuatorial in Malabo, and the Wildlife Conservation Society. This program emphasizes research, ecotourism, and community engagement.
The artisan collective, instead, supports rural communities by promoting sustainable and eco-friendly micro-enterprises. Finally, the Bioko Island Book Series aims to educate children about the remarkable biodiversity of their native land.
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Written by Mirko Cerrone, March 2025