Learn About Red Colobus
Africa’s most endangered group of monkeys
What is a red colobus?
Picture in your mind a chimpanzee or a gorilla. Even though you may have never seen these kinds of animals in the wild, you probably have a good idea of what they look like. But, what if we asked you to picture a red colobus monkey?
Most people don’t know what a red colobus is. And, yet, they are Africa’s most endangered group of African monkeys. In fact, some species of red colobus are among the most threatened primates in the world and one species may already be extinct. So, what’s a red colobus?
Red colobus are monkeys that are only found in Africa. There are actually four kinds of colobus monkeys in Africa, distinguished, in part, by color: red colobus, black and white colobus, black colobus, and olive colobus.
What do red colobus look like?
Each red colobus species differs from one another in hair color and patterns, but they always have some red on them (sometimes on the top of their head, sometimes on their arms, chest, back, or tail, and sometimes all over their body). Even within a species there may be extensive hair color and pattern variation. Here are the recognized species of red colobus...
How big are they?
Body weight of adult red colobus varies considerably across species, ranging from ~5 to 12 kg, as does degree of sexual size dimorphism (difference in body weight between males and females).
Red colobus have a number of features uniquely shared with the other kinds of colobus monkeys. First, red colobus have a large, four-chambered stomach in which is housed microorganisms (such as bacteria) that help to digest cellulose (a major component of plant cell walls) and secondary compounds (produced by plants to deter feeding). This allows red colobus to more easily digest leaves and seeds, which form key parts of their diet. Second, red colobus have thumbs that are greatly reduced in size and their hindfeet are very long. These traits allow red colobus to more easily grasp branches while moving in the canopy and facilitate dramatic, long distance leaps between trees.
What do red colobus eat?
The dietary repertoire of red colobus varies across species, sites, and seasons. However, in general, red colobus typically feed from mature and young leaves (including leaf buds and petioles), flowers and floral buds, fruits (including unripe fruits), and seeds. Much of the foods eaten by red colobus is found in the canopy of the tallest and oldest trees in their habitat. Red colobus have also been observed to feed on bark, charcoal, soil, and invertebrates.
Red colobus are forest specialists. That is, they need forests to live and especially rely on the oldest and tallest trees. But, they can live in a wide variety of forest habitats (from sea level to 2200 m above sea level) including old-growth primary and secondary rain forest, riverine and gallery forest, mangrove swamp, and dry savanna woodland. Within these kinds of habitats, red colobus are found in 18 countries, from Senegal and the Gambia in western Africa to Kenya, Tanzania, and the island of Unguja in Zanzibar in eastern Africa.
Where do they live?
How do red colobus communicate?
Like other primates, including humans, one important way in which red colobus communicate is through vocalization. Red colobus vocalizations, however, are among the most complex of any non-human primate. Their calls can be difficult to classify and distinguish from one another because they often grade into one another and are not always as discrete as those found in other kinds of primates. To listen to some of these calls, here you will find recordings from Dr. Thomas Struhsaker’s collection of vocalizations from 10 species of red colobus.
What is their social system?
There have only been a limited number of long-term behavioral studies of red colobus and those have been limited to the Ashy red colobus (tephrosceles), Bay colobus (badius), Temminck’s red colobus (temminckii), Tana River red colobus (rufomitratus), and Zanzibar red colobus (kirkii). Thus, information about red colobus social behavior tends to come mostly from these taxa and their study sites.
Like most primates, red colobus live in social groups. Red colobus social group size varies between species and even within a species, being influenced by a number of factors such as habitat size and quality, food distribution and seasonality, the presence of predators, and human activities. Across species, social groups have been observed to vary in size from 3 individuals to over 100 individuals, but typically range in size from ~25 to ~40 individuals. Most red colobus groups are multi-male and multi-female (although females always outnumber males), but for some species a typical group may only contain one adult male. In some areas, red colobus social groups divide temporarily and eventually come back together in a process known as “fission-fusion”. In the few species that have been studied in detail, females (much more than males) tend to leave their natal group (the group in which they were born) and move between groups.
Red colobus conservation
The International Union for Conservation of Nature (IUCN) Red List of Threatened Species is the global authority on assessing the extinction risk of nearly 150,000 species. Species are considered by the IUCN to be “Threatened” with extinction if they are classified as Vulnerable, Endangered, or Critically Endangered. These categories represent increasing risk of extinction, respectively. Species are evaluated on a set of criteria to determine if they are Vulnerable, Endangered, or Critically Endangered. These criteria include information on population size, rate of population decline, causes of population decline, and the size, degree of fragmentation, and rate of decline of its geographic range.
Between 2016 and 2020, experts from the IUCN Species Survival Commission (SSC) Primate Specialist Group (PSG) reassessed the conservation status of red colobus. They concluded that every form of red colobus monkey is threatened with extinction, with 14 of the 18 taxa listed as Critically Endangered or Endangered. This makes red colobus Africa’s most imperiled group of monkeys. Indeed, one species, Miss Waldron’s red colobus (Piliocolobus waldroni) may already be extinct. Despite many surveys, Miss Waldron’s has not be sighted alive by scientists since 1978.
Miss Waldron's red colobus may be extinct already
Why are red colobus at a high risk of extinction?
Red colobus populations are primarily threatened by commercial and subsistence hunting as well as forest loss, degradation, and fragmentation. Activities leading to forest loss, degradation, and fragmentation include logging (industrial and artisanal), mining (industrial and artisanal), and agricultural expansion (industrial and subsistence). These activities have already led to the loss and fragmentation of most of the forests in West and East Africa and are eroding Central African forests. Many of the trees on which red colobus feed and travel are also commercially valuable and targeted by industrial and artisanal loggers.
Nearly every red colobus species is threatened by hunting. Red colobus are notorious for being extremely susceptible to gun hunting. They are large bodied, they live in large, noisy groups, and they tend not to flee in response to the presence of hunters. In fact, they are often one of the first large-bodied mammals to disappear from a hunted forest, thereby serving as early warning indicators of a healthy forest.
What is being done?
In response to the worsening conservation status of red colobus, over 100 experts from the United States, Europe, and Africa published the first ever Red Colobus Conservation Action Plan. The goals of this plan are to identify range-wide and species-specific conservation priorities to mobilize international conservation organizations, governments, communities, academic and research institutions, zoos and wildlife centers, and concerned individuals to take action to prevent red colobus extinctions and effectively protect viable populations.
The Red Colobus Conservation Action Plan calls for:
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Forest surveys to improve understanding of red colobus distribution, population size, and abundance
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Establishing and improving protected areas
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Engaging with local communities and improving their capacity to work in conservation
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Improving local access to healthcare and family planning services
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Raising awareness of red colobus and their conservation
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Increasing government support for red colobus conservation
A Red Colobus Working Group has been formed to encourage and support the implementation of priority actions identified in the action plan. A Red Colobus Conservation Network has also been established to bring together those working on or interested in red colobus conservation.
The world may lose these animals forever...
This video was created by Partners for Red Colobus with support from Re:wild in collaboration with the Red Colobus Conservation Network. Thank you to Jeff Nesmith / Nesmith Creative for creating the video, Alana Hyman (infographics), and Thomas Struhsaker, Scott McGraw, Rachel Ikemeh, Zoe Melvin, Tim Davenport, Mic Mayhew, John Hart, and Stanislaus Kivai for images.
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Interested in red colobus ecology?
Most of the above information on red colobus behavioral ecology was gathered from the following sources:
The Red Colobus Monkeys: Variation in Demography, Behavior, and Ecology of Endangered Species by Thomas Struhsaker, 2010. https://doi.org/10.1093/acprof:oso/9780198529583.001.0001
The Natural History of African Colobines by John Oates (in Colobine Monkeys: Their Ecology, Behaviour and Evolution, 1995, A. G. Davies and J. F. Oates (Eds.), Cambridge University Press, pp. 75-128).
Additionally, a recent overview of red colobus can be found by reading:
Korstjens, A., Hillyer, A., & Koné, I. (2022). Red Colobus Natural History. In I. Matsuda, C. Grueter, & J. Teichroeb (Eds.), The Colobines: Natural History, Behaviour and Ecological Diversity (Cambridge Studies in Biological and Evolutionary Anthropology, pp. 108-127). Cambridge: Cambridge University Press. doi:10.1017/9781108347150.010