ROLOWAY MONKEY

Cercopithecus roloway

Geographic Distribution and Habitat
Roloway monkeys (Cercopithecus roloway), also known as Roloway guenons, are Old World monkeys endemic to Ivory Coast and Ghana. In the thick canopies of moist, old-growth, lowland, and swamp forests, they remain fantastically out-of-sight. Their elusive natures, combined with the complicated terrain of their habitats, makes tracking this species difficult and may affect the overall accuracy of population surveys.

Once occurring from the Sassandra River in southern Ivory Coast, north to the Ghanan city, Goaso, and east to the Pra River, today, the few Roloway monkeys known to exist in the wild are confined to the scarce pockets of jungle still relatively undisturbed in Tanoé and Kwabre forests, in Ivory Coast and Ghana respectively. This species has a strong preference for primary forests and is incapable of surviving in environments degraded more than a little by human activities.

The Roloway monkey was formerly considered a subspecies of the Diana monkey. Though they look strikingly similar, and are closely related, they are now considered two distinct species.

Roloway monkey geographic range. Map: IUCN, 2018
Zooming in to the Roloway monkey's geographic range shows that it is extinct in most of it historic range. Golden tan areas shows where the species still lives. Click map to enlarge. Map: IUCN, 2018

Size, Weight, and Lifespan
Roloway monkeys are among the largest guenons in existence. Males, with an average head and body length of 25 inches (64 cm), are slightly larger than females, 22 inches (57 cm). Their tails, longer than their bodies, more than double their overall lengths!

Males weigh in at a staggering 11 pounds (5.2 kg) compared to females, at 5 pounds (2.3 kg).

Their average life spans in the wild are estimated at 20 to 30 years.

Appearance
Roloway monkeys are similar in appearance to Diana monkeys, a species with which they were once conflated. Both have dark gray fur covering much of their torsos, with notable patches of crimson on their lower backs and red fur along their inner thighs. In stark contrast, their chests and exterior thighs are a bright beige color. The same hue marks their forearms, ears, and distinguished long beards flowing from their chins.

A few traits do set Roloway monkeys apart from Diana monkeys, of course. Most notable are their longer beards, which grow a full 2/3 longer than their cousins’. The stripes of beige fur across their brows also appear more defined than Diana monkeys’. Less prominent are Roloway’s lack of ear tufts, the lighter colored fur on their inner thighs, and that their crimson patches on their backs tend to go higher up.

Males are distinguishable from females by their generally larger framed bodies and longer canine teeth. Otherwise, the sexes look quite similar.

Photo credit: Hans Hillewaert/Creative Commons

Diet
Roloway monkeys are omnivorous primates, partaking in fruits, insects, leaves, and flowers to achieve their nutritional needs. This species is eminently insectivorous, however, hunting down the larger invertebrates that crawl through the canopy as well as foraging their eggs and larva. 

Some evidence suggests these monkeys’ diets may change seasonally. Inhabitants of Bia National Forest, in Ghana, were observed to eat more insects in the wet season and more fruit in the dry season. Such a trend may have more to do with the natural abundance of resources throughout the year than it does these monkeys’ preferences, however. More research needs to be conducted in order to find out. Unfortunately, it is possible that the populations in Bia National Forest no longer exist to be studied.

Behavior and Lifestyle
Roloway monkeys are active during the day, roaming the forest with their troops in search of insects or fruit to eat. They scurry along branches on all fours from tree to tree in a direct and unassuming manner—rarely making the kinds of acrobatic leaps that could attract unwanted attention.

In addition to being extremely rare, Roloway monkeys are characteristically elusive. They not only avoid humans, but actively flee whenever they are close. Combined with the physical difficulties of tracking them in the swampy, dense forests they call their homes, researching this species to a meaningful degree has proven essentially impossible. Much remains unknown regarding their behaviors and lifestyles.

Daily Life and Group Dynamics 
Groups of Roloway monkeys spend much of their day traveling to find food, eating and resting between meals. During rest periods, their group takes time to socialize. Infants play, practicing the types of skills that will help them develop into successful adult Roloways, and adults groom each other, forming and nurturing their relationships and bonds.

Like their closest relatives, Diana monkeys, each group is composed of a single male, multiple females, and their offspring. In the few places where Roloways are left, group sizes vary greatly, averaging 6–22 members. With their overall numbers so drastically low and the untouched habitat their survival depends upon rapidly dwindling, it is more than likely that these statistics speak to a species in crisis rather than one going about its natural existence.

Roloway monkeys are known to fraternize with other species of monkeys, particularly other guenons, with whom they share their ranges. These include the lesser spotted-nosed monkey, the Lowe’s monkey, the olive colobus, and the white-crowned mangabey. Typically, species that associate in this way do so because there is greater safety in greater numbers.

Currently, due to their elusiveness and severe scarcity as a species, very little is known regarding Roloway monkeys’ daily lives and group dynamics. Much of what is surmised has been based off our knowledge of Roloways’ closest relatives, Diana monkeys. But as long as we lack up-to-date research that no longer conflates these two species, what these species’ true similarities and differences are will remain uncertain.

What Does It Mean?

Bushmeat:
Meat from wildlife species that are hunted for human consumption, generally in tropical forests.

Conflate:
Combine two things into a composite whole.

Disturbed Habitat:
A temporary change in environmental conditions that causes a pronounced change in an ecosystem.

Dominance hierarchy:
A type of social hierarchy that arises when members of a social group interact, often aggressively, to create a ranking system. In social living groups, member are likely to compete for access to limited resources and mating opportunities. 

Endemic:
Native or restricted to a certain area or country.

Estrus:
A recurring period of sexual receptivity and fertility in many female mammals.

Habitat fragmentation:
The process by which a large, continuous stretch of habitat gets divided into smaller, disjointed patches of habitat.

Invertebrate:
An animal without a backbone (spine), including arthropods, mollusks, myriapods (such as earthworms, leeches, millipedes, and centipedes), sea anemones, and corals.

Old World monkey:
Monkeys native to Africa and Asia.

Omnivore:
An animal or person who eats food of both plant and animal origin.

Polygynous:
A mating system in which one male mates and lives with multiple females.

Primary forest:
Also termed old-growth forest, virgin forest, or primeval forest—a forest that has attained great age without significant disturbance and thereby exhibits unique ecological features and might be classified as a climax community, an ecological community in which populations of plants or animals remain stable and exist in balance with each other and their environment.

Swamp forest:
Peat swamp forests are tropical moist forests that grow in permanently water-logged areas with mineral-deficient water; the waterlogged soil prevents dead leaves and wood from fully decomposing, over time creating a thick layer of acidic peat. Peat swamp forests are typically surrounded by lowland rainforests on better-drained soils, and by brackish or salt-water mangrove forests near the coast. 

Visit the Glossary for more definitions

Communication
Roloways are social monkeys who likely have sophisticated methods for communicating with each other. They are known to make a number of alarm calls that alert other members of approaching potential threats—humans, for instance. Furthermore, the extensive grooming they participate in on a daily basis is an important way of forming and nurturing relationships, which helps to keep group politics peaceful.

Other guenon species are already known to exhibit complex communication methods, using a number of vocalizations, body postures, physical gestures, and facial expressions to navigate social hierarchies and to share information about their environments with members of their groups. The specific means by which Roloway monkeys do so merely await successful research.

Reproduction and Family
Due to being so elusive, our current understandings of Roloway monkeys’ reproductive cycles and family ties are limited to what we know about Diana monkeys and other guenon species.

Diana monkeys reproduce according to a polygynous system, where the lone male in a group mates with the many females, ensuring that all the offspring he looks out for are his own kin. Roloway monkeys live in groups that look similar and so, likely operate according to this same system. But research is still needed to determine if this is true.

Guenon species typically do not have a specific breeding season. A female can enter her 30-day estrus cycle at any point in the year, though this may be affected by environmental factors such as the abundance of food. A female Diana monkey gives birth to a single offspring. Twins are possible, but rare. She acts as the primary caretaker, carrying and nursing her young while the male watches for and defends against potential threats. A Diana monkey becomes a mature adult sometime between 3 to 4 years of age. At this stage, males disperse to found or conquer their own groups while females remain with their natal groups indefinitely.

Again, until researchers are able to conduct more thorough research of rare and elusive Roloway monkeys, their exact behaviors and ways of life will also elude us.

Fun Facts

Some historical records suggest Roloways may have once lived as far east as Togo. But many researchers doubt the provenance of the museum specimens in question.

In 2020, a trap camera in Tanoé Forest captured the world’s first and only footage of a Roloway monkey in the wild. 

A baby Roloway monkey was born at the Yorkshire Wildlife Park in the United Kingdom in October 2020—marking a huge success for one of the European-based breeding programs trying to help bring Roloways back from the verge of extinction.

Photo credit: Damian Entwistle/Flickr/Creative Commons

Ecological Role
​As fruit eaters, Roloway monkeys contribute to the health of their forest homes by dispersing seeds through their feces as they travel to their different feeding locations. Their healthy appetite for insects also helps to keep those invertebrate populations in check.

Conservation Status and Threats
The Roloway monkey is classified as Critically Endangered by the International Union for Conservation of Nature (IUCN, 2019), appearing on the IUCN Red List of Threatened Species—its threat level increased from the Endangered status it received in its last assessment, in 2008, when it and the Diana monkey were still treated as the same species.

As big-bodied primates, these monkeys have long been prized by local hunters for their meat. In Ghana, the bushmeat trade is responsible for decimating populations of Roloway monkeys in only the last several decades—leading to more than a 90% decline! Lack of their vigilant enforcement has rendered what policies are in place to protect these monkeys essentially. Most recent surveys of two national parks and several protected forest reserves—places where Roloways were once plentiful—reported zero sightings. With so few individuals left in the wild, however, hunting Roloway monkeys has rapidly decreased to the point where it is now unprofitable to go after this species specifically. 

On top of uncontrolled poaching, Roloway monkeys are also greatly threatened by habitat loss. Logging and charcoal production, as well as conversion of forests for agriculture, are human projects that have destroyed acres upon acres of their prime habitat. Infrastructural projects, like roads, fragment what little adequate forests remain. All primates deal with habitat loss as a threat, but Roloway monkeys are a species especially sensitive to forest degradation. This means that even the slightest changes in their ecosystems can have devastating effects on their ability to survive and procreate. In spite of this, human activities have steadily increased, unabated, in the areas where they live. Correction: once lived—Roloway monkeys are no longer found in the majority of the areas where they used to thrive.

Conservation Efforts
The future of the Roloway monkey looks bleak. With fewer than 2,000 individuals estimated to be left in the wild, the Roloway monkey is now considered one of the 25 rarest primates in the world, and is on the fast track toward extinction if drastic measures are not taken immediately.

Currently, the only significant populations of Roloway monkeys are known to live in two forests: Tanoé Forest, in Ivory Coast, and Kwabre Forest, in Ghana. A couple individuals spotted as part of mixed-primate groups in Dassioko Sud Forest Reserve suggests the possibility that other groups, overlooked by surveys, do exist. However, this in no way means likely.

This species is included in the Convention on International Trade in Endangered Species (CITES) Appendix II and marked as a Class A animal of the African Convention of Nature and Natural Resources. While these sorts of recognitions are significant, their meaningfulness is underwhelming in the absence of proper policy-making and enforcement.

Conservation projects involving local communities have been developed, and are under way in Tanoé and Kwabre forests. But these need to be strengthened, perhaps with the help of national and international conservation agencies. Unfortunately, the severe habitat degradation and loss that has affected these areas are not necessarily reversible to an extent or speed that could help Roloway populations meaningfully increase. Other means may be necessary to make an impact and more research, including surveys, needs to be conducted before conservationists can know how to really turn things around for this species on the verge of extinction.

Though less than ideal, the Roloway’s last best hope may lie breeding programs that can keep Roloways in existence long enough to have adequate forests into which they can one day be released.

 References:

  • https://www.iucnredlist.org/fr/species/4232/92384429
  • https://www.alltheworldsprimates.org
  • https://animaldiversity.org/accounts/Cercopithecus_roloway/
  • https://www.rewild.org/press/tropical-treetop-cameras-capture-first-ever-wild-footage-of-critically-endangered-roloway-monkey
  • http://static1.1.sqspcdn.com/static/f/1200343/27605166/1498392083017/Osei_et_al_roloway_Ghana_Afr_Prim_10_2015.pdf?token=V%2FMRYXlC92S1YxIVrkGmwuQjIAs%3D
  • https://www.zoo-mulhouse.com/en/le-parc/animaux/diana-monkey/
  • https://www.rainforesttrust.org/projects/protecting-cote-divoires-primates/
  • https://africanconservation.org/critically-endangered-roloway-monkey-returns-home-to-ghana/
  • https://www.wapca.org/field
  • https://www.yorkshirewildlifepark.com/yorkshire-wildlife-park-celebrates-uks-first-rare-roloway-monkey-birth/

Written by Zachary Lussier, June 2021