Lesser Spot-Nosed Guenon, Cercopithecus petaurista
LESSER SPOT-NOSED GUENON
Cercopithecus petaurista
Geographic Distribution and Habitat
Lesser spot-nosed guenons are native to western Africa, residing in the countries of Côte d’Ivoire, Ghana, Guinea, Guinea-Bissau, Liberia, Sierra Leone, Togo, and, possibly, southeastern Senegal. These enchanting primates belong to the family known as Cercopithecidae, and they go by several aliases: lesser white-nosed guenon, lesser white-nosed monkey, lesser spot-nosed monkey, and lesser spotted monkey.
Tropical rainforests and woodlands that include primary, secondary, gallery, swamp, and mangrove forests, along with forest-savanna mosaic landscapes, coastal scrublands, and farm bush, provide habitat to this adaptable species. The guenons frequent the top layer of the forest understory, at times venturing upward into the canopy like those residing within Täi National Park, Côte d’Ivoire, where individuals have been spotted at elevations of 44 ft (13.3 m). The highest elevation recorded for the species is 3,281 ft (1,000 m) on Mt. Bintumani, within old-growth primary rainforests of Sierra Leone’s Loma Mountains.
Guenons are the largest and most diverse primate group in all of Africa. The genus Cercopithecus, of which the lesser spot-nosed guenon is a member, includes at least 33 species and 47 subspecies.
The lesser spot-nosed guenon is the “parent” species to two subspecies, or “children.”
- Eastern lesser spot-nosed monkeys (Cercopithecus p. petaurista) are found east of the Cavally River, residing in tropical forests nearby the village of Souroukou in Côte d’Ivoire. Others reside in western Togo within Fazao-Malfakassa National Park and Danyi Yikpa and Misahöhe forest reserves along the Kamassi River.
- Western lesser spot-nosed monkeys (C. p. buettikoferi) are found west of the Cavally River, residing in tropical forests along the border of Liberia and Côte d’Ivoire. Others reside in Guinea-Bissau’s Bijagos archipelago.
Size, Weight, and Lifespan
Lesser spot-nosed guenons have the distinction of being the smallest guenons in the Upper Guinea forest region. Males of the species stand taller and carry more girth than females.
Head-to-body length for adult males is between 1.4 and 1.7 feet (44–53 cm). Their tail adds another 1.9–2.6 feet (57–79 cm) to their frame. They weigh between 8.6 and 11 pounds (3.9–5.0 kg).
Head-to-tail length for adult females is between 1.3 and 1.4 feet (40–44 cm). Their tail adds another 1.7–2.2 feet (52–68 cm) to their frame. They weigh between 5.2 and 8.4 pounds (2.3–3.8 kg).
Lifespan for the species is between 16 and 19 years in the wild. The oldest captive individual (a female who had been born in the wild and later captured) died at age 29.
Appearance
This beguiling guenon could easily be the inspiration for a monkey character in a children’s book—move out of the way, Lorax (patas monkey)! With a furry little face—except for black-bluish facial skin beneath expressive brown eyes that sit beneath a dark brow ridge—and a fuzzy, white, heart-shaped spot punctuating the tip of the nose (hence, the species’ common name), white flanges of fur that extend wildly from either cheek that tickle large, scalloped ears fringed with white strands, and a generous ruff of white fur that overwhelms the throat . . . the lesser spot-nosed guenon is undeniably one of Mother Nature’s more charming (not lesser!) creations.
The grizzled fur coat of this small-bodied primate is olive green with flecks of black and yellow hairs, especially on the crown of the head. Cream-colored fur adorns the abdomen, inner limbs, and underside of the tail. The long fingers and toes are black.
Diet
Lesser spot-nosed guenons enjoy a varied diet consisting of fruits, leaves, flowers, and insects. Figs are a favorite meal, and these primates select from a variety of species that include hairy rock fig (ficus glumosa) and figs of the Chinese Banyan tree (Ficus thonningii). Berry-like fruits from China laurel (Antidesma), persimmons (Diospyros), African nutmeg (Pycnanthus angolensis), sacred garlic pear (Crateva religiosa), and the fruity pulp of the evergreen tree known as Dialium aubrevillei, Fabacea further satisfy their fruit cravings. Other rainforest plants that provide these primates with nourishment include the leaf flower (Phyllanthus), ohia (Celtis zenkeri), guanabanilla (Ouratea striata), boleko nut (Ongokea gore), Raphia palm (Raphia africana), and African oil palm (Elaeis guineensis). Young leaves and new stems from liana plants are also enjoyed, and a sprinkling of insects adds the animal-derived protein to their diet. (Of all guenon species, lesser spot-nosed guenons are the least insectivorous.) On occasion, lesser spot-nosed guenons are known to raid nearby agricultural fields (once their natural habitat), particularly maize (corn) and cacao crops.
Mother Nature has fitted guenons with extremely large cheek pouches (similar to those of chipmunks!); lesser spot-nosed guenons are no exception to this adaptation. These impressive cheek pouches hold nearly as much food as their stomach, allowing these primates to carry food while out foraging and to store these morsels for later snacking.
Behavior and Lifestyle
These are arboreal creatures, spending most of their lives in the trees. Lesser spot-nosed guenons are most commonly found in the forest undergrowth within liana tangles and vines that grow on large tree trunks. They rarely climb to high treetops, and even more rarely descend to the forest floor.
Active during daylight hours, making them diurnal, lesser spot-nosed guenons exhibit cryptic behavior as they cautiously maneuver through the forest (a predator avoidance strategy) while going about their day’s activities. Those living in the forest of Täi National Park, Côte d’Ivoire, spend 45% of their time feeding and foraging, 26% traveling, 24% resting, and the remainder of their day engaging in other activities.
Most often, lesser spot-nosed guenons advance from tree to tree quadrupedally (using all four limbs); their long tails, while incapable of grasping, help them to balance. The species is also known to climb, and far less frequently, leap or run through their treed habitat. While larger branches provide their travel routes, these guenons forage and eat on smaller branches and twigs. Rump pads, scientifically known as ischial callosities, provide them with comfort as they sit on their tushes while enjoying a meal. Of all guenons, lesser spot-nose guenons have the distinction of being the species who sits the most, likely because fruits are usually plentiful and within easy reach. When they must fulfill their daily nourishment with insects, they will climb a tree to find their prey.
At the end of a day’s activities, the guenons select a tree to spend the night.
Predators of this species include the Western chimpanzee (Pan troglodytes verus), leopard (Panthera pardus), crowned-hawk eagle (Stephanoaetus coronatus), and human primates (homo sapiens).
Beneath their grizzled, olive-green coat, the skin of lesser spot-nosed guenons is blue!
Lesser spot-nosed guenons live in family groups (or troops) of 4 to 24 individuals, depending on geographic location, with an average group size of 10 or 11 members. A single adult alpha male typically presides over a group, which includes several adult females and their young.
In Täi National Park, Côte d’Ivoire, group size has been reported as 7 to 16 members, led chiefly by an alpha male with occasional seasonal influxes of outsider males, creating temporary multi-male groups.
Annual home range encompasses between 99–247 acres (40–100 hectares). During a day’s travels, lesser spot-nosed guenons cover between 0.3–1.1 miles (0.5–1.8 km), averaging about 0.6 mile (1 km) a day. They have little interaction with one another, though females occasionally groom others in the family group.
Should members encounter individuals from an outside lesser spot-nosed guenon troop, when home ranges overlap, both males and females behave aggressively toward these nonfamily members. Skirmishes most often occur at feeding trees, with opposing members battling with one another over who gets to eat the fruits.
Given that family groups are led by a solo alpha male, it’s not wild conjecture that young males, upon reaching reproductive maturity, strike out on their own in the hopes of instilling themselves at the head of their own group. Related females likely remain with their mothers, and a daughter’s social status would depend on her mother’s hierarchal ranking in the family group. Such behavior is known to be true of other guenon species, including Diana monkeys (Cercopithecus diana), close cousins to lesser spot-nosed guenons.
Besides their leopard and chimpanzee predators, sympatric species include Diana monkeys, Campbell’s mona monkeys (Cercopithecus campbelli), and many other primate species. Lesser spot-nosed guenons regularly hang out with Diana and Campbell’s mona monkeys, a strategic association that affords the group greater safety from predators.
A plethora of other wildlife species make their home in the region, including: lions (Panthera leo); hippopotamus (Hippopotamus amphibius); West African crocodiles (Crocodylus suchus); African forest elephants (Loxodonta cyclotis); buffaloes (Syncerus caffer nanus); spotted hyenas (Crocuta Crocuta); warthogs (Phacochoerus africanus); giant pangolins (Smutsia gigantea); royal antelopes (Neotragus pygmaeus); a variety snakes and lizards; and many bird species.
Guenons use vocalizations and body language to communicate with one another. These methods of communication are nuanced among the various guenon species.
Alarm calls of the lesser spot-nosed guenon are said to sound like a purring cat. A group’s alpha male initiates this purring alarm call to distract a predator and give members of his troop a chance to escape the potential threat. Different alarm calls are sounded for aerial and ground predators. Guenons recognize one another’s species-specific alarm calls.
Body language, like the open-mouth threat, is used to intimidate potential predators. With their sharp teeth revealed, eyes closed, and their long tails twitching, guenons send a defiant message. While brow raising is common in other guenon species, lesser spot-nose guenons jerk their head from side to side or bob it up and down to make a threat more menacing.
Also like cats, perhaps, lesser spot-nosed guenons use their tails, not just in conjunction with a threat, but to indicate their mood.
While social grooming, or “allogrooming” (a behavioral adaptation that serves to strengthen social bonds with one another) is practiced in the species, the dominant male is most often the recipient (rather than the giver) of this activity.
Lesser spot-nosed guenons appear to have no specific breeding season. After a gestation period of about 7 months, a female gives birth to a single infant, who enters the world weighing a mere 8 ounces (230 grams). The conspicuous, heart-shaped, furred white spot is missing from the tip of the infant’s nose but will grow in over the next few months of life. By this time, they’ve also attained their grizzled, olive-green pelage, like that of their parents.
Wildlife biologists don’t know much more. To get a few clues, or conjecture, about the mating system and reproductive lives of the species, wildlife biologists look to a close cousin, the Diana monkey, who has a social structure similar to that of lesser spot-nosed guenons.
Diana monkeys are polygynous, meaning that the male mates with multiple females. The gestation period for Diana monkeys is only 5 months; however, 2 months shorter than lesser spot-nosed guenons. Mothers nurse their infants for six months. As the primary caregivers (though a group’s other adult females might assist), they are extremely protective of their little ones, carrying them as they go about their day’s activities. Infants are able to climb at just two weeks of age and become increasingly playful. Juveniles attain sexual (reproductive) maturity at about 3 years old.
Their largely frugivorous diet makes lesser spot-nosed guenons important habitat regenerators. By pooping out the seeds of all those fruits they eat, they help to cultivate new growth throughout their range. Their folivorous proclivities (leaf-eating) help to prune their forested environment.
The lesser spot-nosed guenon is classified as Near Threatened by the International Union for Conservation of Nature (IUCN, July 2017), appearing on the IUCN Red List of Threatened Species. Although the species’ wide distribution keeps it from being denoted with a more dire classification, its current threat level is elevated from its 2008 classification as Least Concern. Make no mistake; these primates are imperiled.
Both subspecies are also classified by the IUCN as Near Threatened: eastern lesser spot-nosed monkey (October 2016); western lesser spot-nosed monkey (July 2017).
Total population is unknown, but some researchers conjecture a decline of about 30 percent over 33 years (three generations).
The primary threat against these primates is hunting. While subsistence hunting occurs in some areas, it’s the illegal bushmeat trade, now a major international industry, driving the species’ decline. With the expansion of logging roads into the forest, hunters have easy access to these primates. After having killed so many of the larger-bodied primates in the region (including colobus monkeys and mangabeys), these unscrupulous hunters have placed the much smaller-bodied guenons in their crosshairs. Today, lesser spot-nosed guenons are the most “harvested” of all primate species in their region.
Habitat loss, degradation, and fragmentation further threaten these primates. Pristine forestland continues to be razed and converted into agricultural land, particularly for “cash crops” such as cacao (cocoa), corn, oil palm, and rubber plantations. As example, Marahoué National Park in Côte d’Ivoire underwent a near total conversion of the forest into plantations, with a 93% reduction in forest cover between 2002 and 2008, leading to the local extinction of many primate species, including lesser spot-nosed guenons. Mining operations for “precious” minerals such as gold and diamonds, also destroy precious guenon habitat.
While these primates are known to be resilient, if they have nowhere to live, they cannot survive. Some conservationists believe that the species is already Vulnerable in certain areas, in particular Togo, and may be nationally Endangered. These smaller-bodied guenons are also victims of the illicit wildlife pet trade. Mother guenons are killed and their babies kidnapped, to be sold as pets. Wildlife biologists are right to worry about the species’ future.
The lesser spot-nosed 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. It is also listed as Class B of the African Convention on the Conservation of Nature and Natural Resources.
Lesser spot-nosed guenons reside in several protected areas, including national parks and forest reserves, throughout their range countries. Unfortunately, population numbers are decreasing in these areas, largely due to lack of enforcement of anti-poaching laws. Conservationists call for the strict enforcement of these laws, along with additional research stations, extensive foot and camera-trap surveys that would help determine actual population numbers, and widespread studies of bushmeat sold in markets nearby these protected areas.
Baseline research is needed to protect the two subspecies, the eastern lesser spot-nosed monkey and western lesser spot-nosed monkey, whose insular populations also face risk from the bushmeat trade. As such, researchers call for examination of the ethnographic social drivers (relating to local culture and customs) that fuel this illicit industry. Like their parent species, both subspecies are threatened by other anthropogenic activities, human-caused environmental disruption and destruction.
Likely because of their widespread distribution, relative to other primate species, lesser spot-nosed guenons are not the monkey darlings of a major conservation campaign. They are, however, included in the Species Survival Plans of the Association of Zoos and Aquariums, with the San Diego Zoo Wildlife Alliance/Institute for Conservation Research one participating partner.
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Written by Kathleen Downey, November 2023