WOLF'S GUENON

Cercopithecus wolfi

Geographic Distribution and Habitat

The Wolf’s guenon, also known as the Wolf’s mona monkey, is native to the central basin of the Democratic Republic of Congo (DRC) in west-central Africa. Their particular habitats within this region consist primarily of mature-growth forests and secondarily of newer-growth lowland rainforests and swamp forests.

TAXONOMIC NOTES

There are three recognized subspecies of the Wolf’s guenon, each separated by swamp forest:

  • The Congo Basin’s Wolf’s monkey (C. w. wolfi), which is found between the Congo and Sankuru Rivers
  • The fire-bellied Wolf’s monkey (C. w. pyrogaster), which is found between the Kwango and Kasai-Lulua Rivers
  • The Lomami River Wolf’s monkey (C. w. elegans), which is found between the Lomami and Lualaba Rivers
Wolf's guenon geographic range. Map: IUCN, 2019

Size, Weight, and Lifespan

The Wolf’s guenon ranges in length between 17.5-20 inches (44.5-51.1 cm). The species is sexually dimorphic, which means that there are noticeable physical differences between genders. The females are smaller than and weigh less than the males. The males weigh almost twice as much as females, with an average weight of 10 pounds (4.5 kg) compared to the females’ average weight of 5.5 pounds (2.5 kg). These monkeys usually have a lifespan of around 20 years when living in the wild.

Appearance

All guenons are colorful, and the Wolf’s guenon is no exception! The Wolf’s guenon is dark gray with a red “saddle” on the back. Their arms are black, while their legs are brownish-red. The underside is creamy yellow, occasionally with an orange stripe down the sides. A black mask covers the face and cheekbones, with long yellowish fur covering the lower portion of the face. A bushy gray brow bone (reminiscent of a grandfather’s bushy eyebrows) turns into a reddish tuft that rests on both ears. The expressive face is notable for a long, flat dark nose, a pink mouth and chin, and gold-brown eyes. Their nonprehensile tail is dark gray at the base, turning black as the fur extends to the tip.

Guenons have large cheek pouches—pockets on either side of the jaw that extend down into their throats. The pouches can hold as much food as the monkeys’ stomachs and are handy for stuffing fruit and other foods during foraging expeditions. If interrupted by a rival or predator, the monkey can flee to safety with food securely stored away. Once safely in their perches within the forest canopy, they can enjoy snacking on their meal in peace.

Callous-like pads on the buttocks—known as ischial callosities—provide them with some comfort when resting on branches and other hard surfaces. 

Among guenons, fur color, patterns, and diverse facial markings vary between species. Since many guenons form mixed-species groups that travel and forage together, scientists theorize that similar species that share the same space evolve to look more different from one another so they can more easily tell their own kind from other species, thereby avoiding hybridization. 

Finally, males have a striking blue scrotum, which scientists believe plays a role in attracting females.

Diet

The Wolf’s guenon’s diet varies based on location. They are primarily frugivorous (fruit-eating) and may supplement their diet with young leaves, flowers, seeds, nectar, insects, nestling birds, eggs, lizards, and frogs. 

Behavior and Lifestyle

The Wolf’s guenon is diurnal, meaning they are most active during daylight hours. They are also arboreal, spending most of their time in the trees, traversing the forest, and foraging at a mean height of 50-55 feet (15.2-16.8 m) above ground. They use their long tails to aid in balancing while moving about in the trees, much as a tightrope walker may use a pole.

The Wolf’s guenon primarily forages and feeds during the early morning and early afternoon, with well-deserved breaks for rest in between. Regarding rest, they do not build nests to sleep in at night. Rather, they rest within the branches of the trees.

Besides humans, the Wolf’s guenons’ predators include leopards and crowned eagles. They alert one another to the presence of predators by sounding an alarm call, after which they make a hasty retreat.

Fun Facts

The Wolf’s guenon is not named for wolves but rather in honor of the scientist who first documented them, Dr. Ludwig Wolf.

Guenons, as a whole, are the largest group of African primates.

Daily Life and Group Dynamics

Wolf’s guenons live in groups of up to 12 individuals consisting of a sole alpha male, multiple females, and their offspring. Females remain within the group, while males disperse upon reaching sexual maturity to form small bachelor groups, from which they will one day further split to lead new groups of females. 

While there is great competition between males regarding dominance, females are generally amicable, groom one another, and mutually care for the group’s offspring, maintaining strong social bonds.

Territories are serious business for Wolf’s guenons, and interactions between groups tend to be aggressive, regardless of gender. When an intruder is spotted, territorial boundaries are maintained with females sounding an alarm, summoning the alpha male to defend the territory by challenging the intruder.

Perhaps surprisingly, despite their intolerance for unknown members of their own species, Wolf’s guenons are often found in the company of other primate species. Most often, they can be found alongside the black crested mangabey (Lophocebus aterrimus), but have also been spotted mingling with Allen’s swamp monkeys (Allenopithecus nigroviridis)bonobos (Pan paniscus), colobus monkeys, red-tailed monkey (C. ascanius), and other guenon species. Scientists speculate that these mixed groups most likely form to aid in predator detection. The more monkeys, the more eyes and ears there are to locate potential dangers. Luckily, the various species have different food preferences, thereby reducing the potential for competition over food. Additionally, the various species tend to forage at different heights in the forest or even alter their feeding and rest times, as necessary, to avoid conflicts.

Communication

Wolf’s guenons will bare their teeth in yawn-like grimaces, toss leaves, posture, and stamp on tree branches to demonstrate aggression.

Scientists have documented up to seven distinct calls as part of the Wolf’s guenon’s everyday communications. Alarm calls—loud booming sounds and bird-like chirps—alert one another to danger. These calls vary based on the type of threat and the threat’s location. Wolf’s guenons have also become accustomed to the alarm calls of other primate species with whom they forage nearby. This awareness of the alarm calls of other species is critical in enabling such relatively small monkeys, such as the Wolf’s guenon, to avoid predators. To maintain contact with one another while foraging, Wolf’s guenons will occasionally growl to announce their position within the bustling forest landscape.

Within the realm of tactile communication (i.e., touch), Wolf’s guenons spend extensive time grooming during rest periods. This activity appears to strengthen the bonds between group members.

Reproduction and Family

Wolf’s guenons are polygynous, with one male mating with all of the females in a group. The breeding season lasts from June to December when there is the greatest abundance of food. After a gestation (the length of pregnancy) period lasting from 160-170 days, females bear one (rarely two) offspring. Mothers provide the majority of parental care with several female troop members sharing in the care for one another’s offspring. This practice is known as “alloparenting.” Males contribute by providing protection.

The offspring are often a lighter color than their parents, with their darker adult colors developing when they are four to six months old. Young reach sexual maturity and independence at five years of age, at which time males disperse to find their own group, while females stay with their natal (i.e., birth) group.

Ecological Role

As frugivores, the Wolf’s guenon aids in the regeneration of their forest habitats by dispersing seeds through their feces as they move around their habitats. They also play a role in pollination. Like bees and butterflies, they collect pollen from flowers when drinking nectar. They then deposit pollen on each flower they visit, thereby pollinating the plants.

Conservation Status and Threats

The International Union for Conservation of Nature lists the Wolf’s guenon as Near Threatened (IUCN, 2016), appearing on the IUCN Red List of Threatened Species.

The main threats to the Wolf’s guenon are hunting for the commercial bushmeat trade and habitat loss. 

Guenons as a whole were found to make up 45% of all bushmeat for sale in one of the largest commercial bushmeat markets in their range. In this market, located in the city of Kindu, the Wolf’s guenon was one of the most abundant species for sale.

Their forest habitat is threatened due to ongoing conversion to agricultural land and aquaculture, farming, logging, and wood harvesting. Occasionally, raids on local crops (in land that once belonged to the primates) have been carried out by Wolf’s guenons, adding human-wildlife conflict to the list of threats facing the species. Their potential for carrying viruses and diseases, like Simian foamy virus, which may be contagious to humans, has also contributed to negative perceptions of the species.

The Wolf’s guenon is one of the most common guenon species found in the Central Basin of the DRC. While their population is not severely fragmented across their range, there is a continuing decline of mature individuals due to the multiple threats affecting the species. 

Conservation Efforts

The Wolf’s guenon is 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.

The species is found in protected areas within its range which are regularly patrolled by guards, including Salonga National Park, Lomami National Park, Lomako-Yokokala Faunal Reserve, and Swa-Kibula Hunting Reserve. These patrols, however, are considered to not be sufficient to save the species from the potential of becoming endangered, or worse, extinct.

There are currently neither any action plans nor harvest management plans in place to aid in the protection of the Wolf’s guenon. However, a systematic monitoring scheme is in place, as well as an education plan included in international legislation to increase awareness of the plight of the species.

Overall, further action is needed to protect the Wolf’s guenon from the threats of endangerment and extinction. Laws and policies along with proper compliance and enforcement are necessary to address these critical issues. Additional recommendations include research and monitoring in the areas of Wolf’s guenon population size, distribution, and trends, as well as threats to the species. Conservation planning concerning harvest and trade management is also recommended. Finally, additional monitoring involving trends in harvest level, trade, species population, and the forest habitat needs to be ongoing for the Wolf’s guenon to be able to continue to mature and thrive in their shrinking, yet unique range within the African continent.

References:
  • https://animalia.bio/wolfs-mona-monkey
  • https://animals.sandiegozoo.org/animals/guenon
  • https://www.bioexplorer.net/animals/mammals/monkeys/wolfs-mona-monkey/
  • https://en.wikipedia.org/wiki/Wolf%27s_mona_monkey
  • https://www.iucnredlist.org/species/92466239/166601223
  • https://link.springer.com/content/pdf/10.1186/1742-4690-9-100.pdf
  • https://www.saczoo.org/wolfs-guenon
  • https://southwickszoo.com/our-animals/wolfs-guenon/
  • https://zooatlanta.org/animal/wolfs-guenon/

Written by Sienna Weinstein, February 2024