CENTRAL AFRICAN POTTO

Perodicticus edwardsi

Geographic Distribution and Habitat

The Central African potto (Perodicticus edwardsi), also called the Milne-Edwards’s potto, is a primitive primate species, known as a prosimian, belonging to the suborder Strepsirrhini and to the family Lorisidae. It is native to Central Africa, hence its name. The wide geographic distribution for this prosimian begins in the country of Nigeria, where its range extends from the Niger River and continues southeast through the countries of Cameroon and Equatorial Guinea mainland; stretches southerly into northeast Gabon and Republic of Congo, then east, south of the Congo River, through the Democratic Republic of Congo (DRC); and, finally, into Angola, the species’ southernmost range. The collective climate for the species’ range is a tropical soup of monsoons, high temperatures, and humid weather conditions, with some of the countries offering a dry season as well as a rainy season.

Primary and secondary forest that include montane tropical moist, lowland, and swamp provide habitat for these enigmatic primates. They are also commonly found within colonizing forests and at the edges of these forests. Central Africa pottos typically reside at 4,921 ft (1,500 m) above sea level.

TAXONOMY IN TRANSITION

Prior to receiving its distinct species status, the Central African potto had been classified as a subspecies of the West African potto (Perodicticus potto), along with the East African potto (Perodicticus ibeanus). But genetic studies elevated both these former subspecies to full species status in 2015. Many scientists believe that the Central African potto and East African potto are “long-lost sisters,” having diverged from one another about 5.5 million years ago during the latter part of the geological epoch known as Miocene. While the East African potto is “parent” to two subspecies, such lineage remains unconfirmed for the Central African potto. That said, some scientists believe that variations among individuals from different countries within the species’ range will lead to the discovery of subspecies. P. faustus, synonymous with P. edwardsi and found in the Congo Basin, has been suggested as a possible “child” (subspecies). These pottos are smaller than other Central African potto populations. Further research is necessary to determine whether the Central African potto is actually a “parent,” and whether these pottos are, in fact, a subspecies.

Adding to the taxonomic rumpus of this intriguing prosimian is another synonym, Pseudopotto martini, informally translated as “false potto.” On the basis of two skeletons, examined in 1996, researchers cite a creature with a longer tail, shorter spine, and other physical traits that distinguish it from other pottos, hence its “imposter” status. One anthropologist has even posited that this creature may represent a family distinct from lorisoids (whose members also include lorises and angwantibos). Other researchers staunchly disagree, arguing that physical features are variable among pottos.

So what does the environmental global authority International Union for Conservation of Nature (IUCN) say about the Pseudopotto martini kerfuffle? The IUCN considers this unknown strepsirrhine primate a misidentified specimen of an East African potto. However, the American Society of Mammalogists considers it to be a misidentified West African potto. At present, the only certainty appears to be uncertainty. Additional research is required to unveil this alleged imposter and give the primate its own classification—or not.

For now, membership in the “potto club” is restricted to the known three geographically diverse species: West African potto, East African potto, and the Central African potto.

Milne-Edwards Potto range, IUCN 2019

Size, Weight, and Lifespan

Male and female Central African pottos weigh about 2 lb (0.9 kg). Adult males are slightly taller at 16.3 inches (41.5 cm), while the average height for an adult female is 14.6 inches (37 cm). Each sex is fitted with a nonprehensile tail that adds another 2.2 inches (5.5 cm) to its body.

Lifespan in the wild is not well documented for pottos. Captive studies of West African pottos indicate a lifespan of 22 to 25 years, perhaps suggesting a similar longevity for Central African pottos.

Appearance

Central African pottos share similar characteristics with West and East African pottos. Physical features including body mass, body size, pelage, and color of eye shine vary among the three species with their geographic range.

Curious-looking, otherworldly, peculiar, weird, adorable (perhaps!)—all are apt descriptors for this tiny, primitive primate. But catching a glimpse of this shy, nocturnal creature is no easy feat, leaving us to look toward a preserved museum specimen and to other pottos for a general description.

Apart from their sexual organs, there is scant difference in appearance between male and female pottos. A thick, closely cropped fur coat in varying shades of creamy brown to grayish brown covers their slender body and limbs. Forelimbs and hindlimbs are equal length. A fluffy tail adds a bit of “poofiness” to the potto’s beguiling appearance.

Bony protuberances (called “tubercles”), concealed by thick skin and the animal’s dense coat, begin at the lower neck and extend along the elongated spine to form what is referred to as a “scapular shield.” This evolutionary adaptation functions both as a defensive mechanism and as protective armor. Long, stiff, whisker-like hairs called “vibrissae” act as environmental sensors and fly out from the scapular shield.

Staring out from a tiny bowling ball of a head are large, widely spaced dark eyes that appear to glow in the dark. This spooky phenomenon is thanks to a reflective layer of eye tissue known as the tapetum lucidum, which allows visible light to be reflected through the eye’s retina, resulting in so-called “eye shine” and equipping these nocturnal primates with enhanced night vision. On either side of the potto’s round head sit two hairless, nondescript ears.

As strepsirrhines, pottos are defined by a moist snout (similar to that of dogs and cats), earning them the colloquialism “wet-nosed” primate. Above their pointy snout and extending laterally from the side of the skull and around the eye sockets (giving the illusion of eyes “bugging” out of their head) is a hairless, bony arched structure (scientifically known as a postorbital bar) that connects to the cheekbone. Other strepsirrhine attributes include a vestigial index finger on each hand and a reduced, sharpened second digit on the foot, euphemistically referred to as a “toilet claw” (used for grooming). Peek inside their mouth and you will see a toothcomb (sometimes referred to as a dental comb), a specialized set of teeth in the front, lower part of the mouth used mostly for grooming.

What Does It Mean?

Anthropogenic:
Environmental disturbance or environmental pollution originating in human activity. 

Colonizing forest:
Refers to the process by which trees colonize new ground from existing local sources. This natural colonization occurs through seed dispersed by birds, mammals, wind or gravity, or by vegetative colonization where new growth sprouts from the stem or roots of adjacent trees. Wildlife biologists regard species colonization of a new habitat patch as an efficiency indicator of biodiversity conservation.

Montane forest:
A forest that grows on the slope of a mountain, regardless of altitude or latitude, within a specific climate, just below the subalpine zone.

Nonprehensile:
Incapable of grasping or gripping (opposite of prehensile: capable of grasping).

Pelage: 
The fur, hair, or wool of a mammal.

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.

Secondary forest:
A forest that has regrown after a major disturbance, such as fire or timber harvest, but has not yet reached the mature state of primary forest.

Visit the Glossary for more definitions

Photo credit: © Ben Evans/iNaturalist/Creative Commons

Diet

Like all pottos, the Central African species eats lots of fruits, making it largely “frugivorous.” Tropical fruit trees provide these prosimians with a banquet; they have a penchant for figs. Their diet fluctuates with the seasons, however. During dry periods when fruits are unavailable, tree gums provide Central African pottos with necessary sustenance. Snails and insects supplement their meal plan. Scientists theorize that, because the insects eaten by pottos are foul-smelling, other animals avoid these dietary snacks. (Apparently, stinky bugs do not cause olfactory offense for pottos.) Occurrences of pottos catching and munching on bats and small birds have been reported.

As strepsirrhine primates, pottos are able to synthesize Vitamin C from their diet.

Behavior and Lifestyle

Pottos are creatures of night (making them nocturnal) who spend the majority of their time in trees (making them arboreal). They move through their treed environment on all four limbs (that is, quadrupedally) slowly, deliberately, and silently. No death-defying acrobatic leaps for these primates. Their opposable thumbs and an opposable big toe on each foot allow them to firmly grasp tree branches as they advance through the forest; their toilet claws lend additional support.

Most of their evening is spent foraging and eating; lesser time is spent socializing. Daytime hours find these prosimians curled up asleep in tree hollows. In Cameroon, mated adult male/female pairs often sleep together or near one another. However, in Gabon, adult males typically sleep alone while adult females sleep with their offspring.

As strepsirrhines, pottos rely less on visual input than do their “dry nosed” primate kin, the haplorhines (of the higher suborder Haplorhini). Fortunately, pottos’ morphological adaptation of a tapetum lucidum provides them with that eye shine that illuminates their nighttime path.

And it’s a good thing that pottos can see in the dark, because predators lurk. Wild, medium-sized cat-like carnivores known as viverrids (belonging to the family Viverridae and to the suborder Feliformia) hunt and eat pottos. Feliform predators of Central African pottos include the golden cat (Profelis aurata); the leopard (Panthera pardus); the primarily frugivorous African palm civet (Nandinia binotata), who is a relative of the mongoose; and the black-legged mongoose (Bdeogale nigripes).

As with other nocturnal primates, pottos are adept at blending into their environment to avoid detection. This predator-avoidance strategy is called “crypsis” in science-speak, more informally referred to as “camouflage.” Dense vegetation allows the pottos to keep themselves hidden. Pottos further deflect attention from potential predators by moving silently, traveling alone or in small groups, and using only discreet vocalizations when communicating with one another.

Mother Nature has given pottos another trick to evade detection by predators. Thanks to an adaptation of vascular bundles in their limb vessels that regulate blood circulation to contracted muscles—a phenomenon called “retia mirabilia”—pottos are able to remain still for long periods of time without fatigue. In cooperation with their super flexible wrist and ankle joints, a prolonged grip allows them to “wait out” lurking predators.

Should pottos find themselves in a situation where they must defend themselves, their scapular shield can save their neck—literally. Those bony protuberances are sharp, and a potto who engages in combat can, with a well-placed head butt, inflict injury to a would-be predator and, hopefully, knock the predator to the ground below.

The scapular shield also provides protection, and a deterrent, to a predator—or another potto—who attempts to chomp down on the animal’s neck. The scapular shield’s stiff sensory whiskers (vibrissae) also play an important, sensory role in keeping a potto safe; tactile sensitivity is critical to the potto’s survival of a life-or-death situation. For example, when a potto tucks his head between his arms in a defensive posture, rendering him unable to see an approaching predator, the vibrissae alert him of the menace. Sometimes, the menace is human.

Potto defensive reactions to human captors include hissing, grunting, baring of their teeth, repeatedly biting the branch where they cling, and, finally, lunging at their attacker. To escape extreme danger, pottos have been known to deliberately release their grip and drop to the ground.

Daily Life and Group Dynamics

Typical group (or “troop”) composition for a Central African potto is 1 to 3 individuals. Upon reaching sexual maturity, a young male strikes out on his own—leaving his birth group for the solitary life or to establish himself within another group.

Wildlife biologists have long believed that Central African pottos are mostly solitary animals. Part of this premise is that these creatures are typically seen alone during their nocturnal activities. However, this view is changing. More recent field research using radiotelemetry and behavioral observations reveals that these pottos possess social networks that vary among the three species. A significant finding is that social networks appear to be related to home ranges. One study puts the average overall home range for adult pottos at 359 acres (145.2 ha).

Overlapping home ranges occur more frequently than researchers initially thought, allowing for increased social interaction with one another, specifically, between a “paired” male and female adult potto. Although no affiliative or sexual behavior was observed between random individuals, outside of the paired couple, the Central African potto’s secretive and elusive nature allows for the possibility these interactions might occur. To further this supposition, researchers cite the relatively small testes size of adult males, a possible indicator that sperm competition is not of great importance for this species.

Central African pottos share their world with an impressive and diverse array of wildlife species. Gorillas, chimpanzees, forest elephants, buffaloes, giraffes, warthogs, wildebeest, hippos, crocodiles, snakes, zebras, pangolins, ostriches, kingfishers, and the black panther—national animal of Gabon—are only some of the incredible animals who live throughout the pottos’ geographic range.

Fun Facts

In English-speaking parts of Africa, “softly-softly,” “bush bear,” or “tree bear” are among the colloquial names for pottos.

Pottos’ neighbors and closely related strepsirrhine relatives are angwantibos. In fact, these prosimians are commonly referred to as a “golden pottos” for their coat color. But they are not pottos, not even “false pottos.” Rather, they belong to the genus Arctocebus. (You could say: “they don’t pass the smell test,” assuming they don’t smell like curry, as do pottos, purportedly, and if you like puns.)

French mammologist Alphonse Milne-Edwards (1835–1900) is credited with “discovering” the Central African potto, hence this primate’s alternative name of Milne-Edwards’s potto.

Communication

Pottos rely chiefly on chemical cues to communicate. To facilitate this communication, Nature has fitted both males and females with large scent glands beneath their tails (in females, the swelling created by these glands is known as a pseudo-scrotum, for its resemblance to the scrotal skin of males). By leaving urine trails and other secretions on tree branches, pottos mark their territory, convey important information about their reproductive status, and reinforce social bonds between a paired couple. Pottos, themselves, are defined by a distinct odor that has been described as “curry-like.”

A potto mother who “parks” her infant (on a branch or inside a tree hollow) to be kept safe while she goes off to forage applies a noxious salivary secretion to her infant’s coat, using her toothcomb. This noxious secretion acts as a natural predator repellant. Parking is reportedly rare with Central African pottos. However, it could be that this practice occurs but has only been rarely observed.

Grooming is a tactile activity that fosters social bonds, occurring between mother and infant and between a paired couple.

Vocalizations are emitted sparingly and discreetly. The most common vocalization is a mother’s soft contact call, a “psic” sound, to her offspring. A barely audible “wheet” call is sometimes heard from an individual. When engaged in combat with an attacker, pottos emit hisses and grunts, accompanied by defensive body posture.

Reproduction and Family

Both female and male Central African pottos are considered sexually mature at about 18 months of age (able to conceive and bear young; able to sire young, respectively). The animals’ mating system is uncertain. Some researchers suggest a polygynous society, where one male mates with more than one female. Other researchers suggest a polygynandrous, or “promiscuous” society, where both males and females have multiple partners.

Foreplay consists of mutual grooming sessions using claws and teeth, accompanied by licking and scent marking one another. These courtship rituals are often performed while the enamored couple hangs upside down from a tree branch (thank goodness for those strong, opposable toes!).

Breeding occurs year-round, varying by region. After a gestation period of about 193–205 days (with an average of 197 days), a female gives birth, usually to a single infant but occasionally to twins. Birth weight is a mere 1–1.8 oz (30–52 g). An infant instinctively clings to the belly of her mother, later riding on her back as mom travels. Mothers nurse their young for about six months, upon which time infants are fully weaned.

A reproductive female potto gives birth once or twice a year.

This is the closely-related West African potto

Ecological Role

Thanks to their largely frugivorous diet, Central African pottos help to replenish their forested habitat by dispersing the seeds of the fruits they eat, via their feces.

Conservation Status and Threats

The Central African Potto is classified as Least Concern by the IUCN (2016), appearing on the IUCN Red List of Threatened Species. While these monkeys are considered common and widespread, their populations are declining—particularly in the species’ eastern range—due to habitat destruction. But the IUCN has not yet deemed a higher threat category necessary, citing “no evidence of significant range-wide population decline.”

Loss of habitat poses a major threat to the species. Slash-and-burn agriculture is especially devastating to these primates. Not only do they lose their forested home, but often their lives. Because this anthropogenic activity occurs during daylight hours, when the pottos are sleeping, they are taken by surprise and cannot easily escape.

Those pottos who live near human settlements are hunted and killed for their flesh, known as “bushmeat.” They are also killed for their body parts, used in traditional medicine and rituals, and used to make drums (from their skins).

Conservation Efforts

The Central African Potto 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 also listed as Class B of the African Convention on the Conservation of Nature and Natural Resources, a continent-wide environmental protection law signed in Algiers (capital city of the North African country of Algeria); hence, the law is also known as the Algiers Convention.

While some populations of these monkeys live within protected areas, wildlife biologists state that further studies are necessary to fully understand the overall impact of habitat loss and the grim toll of hunting, to ascertain an accurate conservation status.

References:

  • https://www.iucnredlist.org/species/136852/91996061
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Written by Kathleen Downey, June 2022