King Colobus, Colobus polykomos
KING COLOBUS
Colobus polykomos
Geographic Distribution and Habitat
The king colobus (Colobus polykomos), also known as the western black-and-white colobus, is native to the tropical lowland and montane rainforests on the western coast of Africa, from Gambia to Côte d’Ivoire. They have a strong preference for primary forest, and only rarely inhabit secondary forests or habitats that are degraded.
Size, Weight, and Lifespan
Male king colobuses weigh about 22 lbs (10 kg), and females are about 18 lbs (8 kg) on average. The length of the head and body ranges from 17 to 28 inches (45–72 cm), with the tail adding another 20–39 inches (52–100 cm) in length. This size difference is the species’ only sexually dimorphic trait. Their average lifespan in captivity is 23 years, and their lifespan in the wild is unknown—but likely lower than this.
Polygynandry:
A mating system in which both males and females have multiple mating partners during a breeding season.
Polygyny:
A pattern of mating in which a male animal has more than one female mate.
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Appearance
King colobus monkeys are mostly black, with striking patches of long white hair framing their face. Long patches of silvery-white hair stream from down each shoulder, meeting at the lower back like a “U.” Their tails are very distinctive in appearance: the portion closest to the body is thin and black, while the rest is covered in long white hair. The amount of white hair on the tail varies by individual—in some, it is only the very tip, while in others, it covers nearly the entire tail. Unlike other black-and-white colobus monkeys, their tail does not fluff out into a dramatic “plume,” but rather remains narrow.
Newborns are born with white hair and black hands and feet. They develop their black coat as they age.
Unlike most other primate species—but like all colobus monkeys—king colobuses do not have thumbs. Instead, they have a small rounded projection where their thumb would be. Their thumbs were lost over the course of evolution, possibly because they actually became a hindrance as they navigated through the thick rainforest canopy. Their fingers and hands are very long, allowing them to firmly grasp tree branches as they move about arborally.
Diet
The king colobus’s diet consists mostly of leaves, supplemented by fruits and flowers depending on seasonal availability. Because leaves have relatively little nutritional value, they must eat large quantities of them to meet their nutritional needs. Occasionally, they eat charcoal, which helps to eliminate chemicals that are toxic or that slow down digestion.
A unique feature among colobus monkeys is their sacculated stomachs. Their stomachs are large and compartmentalized, similar to the stomach of a cow. This allows them to use bacterial fermentation to break down their food, which is typically low in nutritional value and eaten in large quantities. This process is very slow, but it allows the monkeys to process the cellulose fiber that they would otherwise not be able to digest. The ability to consume foods that others cannot is an evolutionary adaptation that gives them a distinct advantage over other species.
Behavior and Lifestyle
King colobus monkeys are highly arboreal. As such, they primarily live in trees, but often forage on the ground too. On a daily basis, they forage in a path only about 1600 feet (500 m) long, a relatively short distance. Because of their dietary requirements, they spend the better part of the day foraging.
The word “colobus” comes from the Greek word kolobós, meaning “truncated” or “mutilated,” a reference to their absent thumbs.
King colobus monkeys are diurnal (active during the day) and spend the majority of their time in trees. They live in groups of 3 to 4 adult females and 1 to 3 adult males. Males don’t often interact with each other, and they maintain a dominance hierarchy. While female-female aggression does occur, females tend to be closer to each other, engaging in grooming behavior with one another.
A troop’s home range is about 54 acres (22 hectares) on average, with home ranges of different groups overlapping significantly. This leads to frequent intergroup interactions. Most of the time, when different groups come into contact with each other, chases and fights ensue; peaceful interactions between different groups are relatively rare. The motivation behind this intergroup aggression differs between males and females. Female aggression during intergroup interactions is largely motivated by food procurement, as reproductive success is strongly dependent on having sufficient access to food. For males, these intergroup interactions offer new reproductive opportunities.
Successfully defending his resources and territories may attract new females to a male’s group. Sometimes, males will even harass the females and engage in infanticide, killing their infants, in order to force mating receptivity upon the female, who is not receptive to mating as long as she is nursing an infant. This is further motivation for the female to seek out the strongest male she can—to protect herself, her offspring, and her resources.
King colobus monkeys have two main types of alarm calls: snorts and roars. The main purpose of the calls is to maintain distance between groups, or between male members of the same group. When separate groups encounter one another, males engage in aggressive displays. Alarm calls are also sounded when a predator is threatening the group. Interestingly, different types of predators elicit different patterns in alarm calls. For example, the monkeys respond to leopards with a snort followed by several roars, and to crowned eagles with no snorts and many roars.
The king colobus mating system is not fully understood. Some believe them to be polygnous—one male mating with several females—while other sources cite that they are polygynandrous—both males and females taking on multiple sexual partners.
Some evidence suggests that females give birth year round, while other evidence suggests that birth takes place during the dry season. It is possible that different populations exhibit different mating systems. Gestation is 175 days long on average (almost 6 months), and females produce one offspring every 20 months, on average. Sexual maturity is reached at about two years of age.
Females are the primary caretakers of offspring, providing nursing, protection, and grooming, as well as carrying the infant until he or she is old enough to move independently. It is unclear what the male role, if any, is in rearing offspring.
As leaf, fruit, and flower eaters, king colobus monkeys are important seed dispersers. In addition, they may be prey for numerous species, including raptors, leopards, and large snakes in the case of young.
King colobus monkeys are listed as Endangered by the International Union for Conservation of Nature (IUCN, 2019). In the past thirty years, its population has likely dropped by more than 50%. The primary threat to the survival of the species is uncontrolled hunting for bushmeat and their pelts throughout their range, coupled with forest loss, degradation, and fragmentation.
Because the king colobus does not successfully thrive in degraded habitat and relies on primary forest, a rainforest doesn’t necessarily need to be clear-cut to be rendered unsuitable for the species, only degraded. Even replanting a forest that was clear-cut won’t be enough for the species to thrive, since the monkeys rely on primary forest that has developed its unique ecological features over hundreds of years.
While Africa may be well known for its charismatic savanna species, its rainforests provide a home to about half of the animal species on the continent, while constituting a far smaller percentage of land area compared to the savanna. The rainforests of Africa have an unfortunately sordid history, being the site of the 19th century exploitation in the Belgian colony of Congo, where thousands of native people lost their lives while being forced to harvest wild rubber. Unfortunately, exploitation of the rainforest has continued in the centuries since then, with the west African rainforests (the habitat of the king colobus) being the most severely impacted. Almost 90% of the original rainforests of west Africa are gone, with most of the remainder being significantly degraded and fragmented. Desertification, a type of land degradation in which fertile land, including rainforest, suffers a permanent loss in productivity, is a significant threat to the rainforests of west Africa. Many parts of the king colobus’s range are extremely vulnerable to desertification.
Current rates of deforestation of the African rainforests are relatively low compared to the rest of the world—between 2000 and 2010, an average of 0.72 million acres (0.29 million hectares) of forest were lost per year, a decrease by about half from the previous decade. However, despite the slowed rate of deforestation, it is important to remember that it is still deforestation, and a far cry from a net increase, or even stability, in the acres of habitat. And because the king colobus, and many other species, rely on primary forest, even replanting these lost trees won’t replace the lost habitat.
The king colobus is listed under Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), which controls trade of the species to prevent it from becoming endangered, and Class A under the African Convention on the Conservation of Nature and Natural Resources, the highest level of protection under this treaty, which completely bans the hunting and collection of this species except under very specific circumstances.
There are several protected areas that maintain habitat for king colobus monkeys, including Sapo National Park in Liberia, Tai National Park in Côte d’Ivoire, and Tiwai Island Sanctuary in Sierra Leone. However, these national parks only make up a small fraction of the species’ total range.
The Great Green Wall is an initiative by the African Union to plant a wall of trees 9 mi (15 km) wide and 4,400 mi (7,100 km) long along the southern edge of the Sahara Desert to help prevent the spread of the desert. If successful, this proposal could potentially save crucial habitat for the king colobus, which is entirely reliant on the rainforest.
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Written by K. Clare Quinlan, October 2019. Conservation status updated July 2020.