EAST AFRICAN POTTO

Perodicticus ibeanus

Geographic Distribution and Habitat

The East African potto (Perodicticus ibeanus), also known more simply as the eastern potto, occupies an extensive range at the very center of the African continent. Though the largest portion of its range falls within the Democratic Republic of Congo, it also juts into several neighboring countries: the Central African Republic to the north, and Rwanda and Burundi to the south. To the east, the East African potto’s range narrows into a thin strip across the lower half of Uganda, north of Lake Victoria, before ending just over the border of Kenya.

Represented on a map, this strepsirrhine primate’s geographical distribution assumes a funny shape. It might look nonsensical to some. East African pottos are not beholden to the lines humans draw on their maps, but rather to where their livable habitats begin and end.

Most common at forest edges, East African pottos live in an array of diverse habitats, including lowland, montane, swamp, flooded, primary, secondary, colonizing, riverine, and disturbed forests. The mean average rainfall throughout its range is between 24 and 90 inches (60–230 cm) annually. The fact that they can live in so many habitats with such considerable differences in rainfall suggests these are hardy and adaptable primates, capable of surviving under diverse sets of circumstances.

TAXONOMY IN TRANSITION

Pottos’ slow loris cousins in Asia were recently discovered to be a much more diverse genus than previously believed. At one point, only a single species of slow loris species was recognized. Now, there are eight—and possibly more! Could the same be true of pottos? Only more research can tell us for sure. However, three species of pottos are already recognized today, where recently there was only one.

For now, our knowledge describes two subspecies of East African pottos: the nominate type species (Perodicticus ibeanus ibeanus) found in the area described above, and another known commonly as the Mount Kenya potto (Perodicticus ibeanus stockleyi). The latter is believed to be endemic to the wet forests of Kenya’s central highlands, perhaps isolated to only a few forests growing on the slopes of Mount Kenya. However, Mount Kenya pottos have not been spotted in 80 years, and our only knowledge of them comes from a single female collected in 1938. The most recent surveys conducted in the region as of 2001 did not find any evidence to suggest their continued existence in the wild, but there are still a few places researchers have to keep looking.

East African potto range, IUCN 2019

Size, Weight, and Lifespan

East African pottos are relatively small primates. The average male measures roughly 13.7 inches (34.8 cm) from his head to the base of his tail. Females tend to only be about an inch shorter (12.8 inches/32.5 cm) than males, but their lengths can differ up to two inches (5.1 cm). Short stumpy tails add about two inches (5.1 cm) to their overall length. Females are known to weigh about two pounds (861 grams), but official measurements have not been taken for males.

It is currently not known how long East African pottos live in the wild, but individuals have been known to live more than 20 years in captivity.

Appearance

A potto has a long and slender body and a small, arrow-shaped head covered in brownish-gray fur. Its wet nose sticks out prominently at the tip of the “arrow.” Two hairless ears form tiny arches at the top of its head. However, its most striking feature is the eyes—round and bulging vortexes, big and sensitive enough to allow it to see in the dark.

Pottos are a species with many look-alikes—some more believable than others. Many people mistake them for the more renowned tree sloths native to South America. While both are arboreal mammals, their resemblance is merely coincidental.

To others, pottos look like a type of monkey. Though more closely related than sloths, pottos represent a different kind of primate than monkeys. Their closest relatives are angwantibos, another species of prosimian whose golden fur and uncanny resemblance have earned them the misnomer “golden pottos.”

The slow and slender lorises that populate Asia—also prosimian primates—are close relatives of pottos. In addition to their continents of origin, two key differences between the genera are their size and their markings. Lorises are smaller than pottos, and pottos tend to have plainer markings, especially on their faces, compared to many lorises.

The closely-related West African potto

What Does It Mean?

Arboreal
Physically adapted to living primarily or exclusively in trees.

Canopy:
Beneath the emergent layer, the canopy layer is the primary layer of the forest and forms a roof over the two remaining layers (the understory and forest floor). Many animals live in this maze of leaves and branches, where food is abundant.

Crypsis:
In ecology, the ability of an animal to avoid observation or detection by other animals through methods such as camouflage, nocturnality, subterranean lifestyle, and mimicry.

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

Gene flow:
The transfer of genes from one population into another through breeding.

Genus (plural, genera):
A biological classification, or ranking, of living beings that includes a group(s) of species that are structurally similar or “related” to one another through evolution.

Inbreeding:

The breeding of closely related individuals, especially over many generations.

Infant parking:
Refers to mothers leaving their young alone in the nest at night.

Omnivorous:
Having a diet that consists of food of both plant and animal origin.

Strepsirrhine or strepsirhine: 
Relating to the primate suborder Strepsirrhini, consisting of lemurs, lorises, and bush babies, who characteristically have moist areas around their nostrils.

Subspecies:
A population usually restricted to a geographical area that differs from other populations of the same species, but not to the extent of being classified as a separate species.

Visit the Glossary for more definitions

Diet

East African pottos are omnivorous. Their diets vary seasonally and regionally, from habitat to habitat, and they make do with the variety of resources they come across during their nightly excursions. In general, they eat a large selection of food from all levels of the forest but prefer items from high in the canopy. Ripe fruits, gums, nectars, and invertebrates make up the bulk of their meals, but they have also been observed to eat bird eggs, frogs, and even some mosses. On occasion, they may even eat bats!

A number of adaptations, both physiological and behavioral, give pottos special abilities to exploit several untapped niches. For instance, very large and powerful jaws allow pottos to eat fruits that other creatures cannot access or efficiently process. Furthermore, a potto’s stomach is highly expandable, capable of holding up to 8% of its body weight at a time! This means they can stuff themselves full of fruit quickly and return to the denser foliage before drawing too much attention to themselves from predators.

A wet nose and a sensitive olfactory system help pottos track down insects amongst the dense foliage. Once found, coordinated and lightning-quick reflexes—like something out of an old kung-fu movie—ensure their prey don’t have a chance to escape. Pottos have also adapted to eat species of insects most other animals of the forest do not find palatable, thus eliminating their competition for these protein-packed snacks.

Behavior and Lifestyle

Pottos have evolved certain traits and behaviors to fit a very particular lifestyle. Crypsis refers to a set of strategies certain animals use to avoid being noticed by predators. Such animals have adapted their traits and behaviors to work within the uniqueness of their environments. The most well-known use of crypsis is camouflage, but many other strategies exist, and pottos make use of several!

First, a potto’s arboreal lifestyle keeps it off the ground where it would otherwise be vulnerable to predation. Additionally, its small size allows it to hide in patches of dense foliage where they find even more protection.

Many primates, like monkeys and apes, are gregarious animals. This means they routinely hang out in groups, casually socializing throughout the day. Pottos, on the other hand, never gather in groups since doing so would risk drawing too much attention to themselves. Instead, a potto leads an extremely solitary life. This way it can move through the forest quietly, going craftily about its business, before finding a hiding place to sleep.

A potto sleeps during the daylight hours tucked away in an inconspicuous nook or cranny—wherever it may squeeze itself that offers the most protection. At nightfall, it wakes and sets off into the forest in search of food. Its big eyes pierce the darkness, rendering it no obstacle as it crawls steadily along.

When faced with a threat, a potto freezes in its place, hoping to remain unseen. Pottos have special veins in their muscles that allow them to remain perfectly motionless without tiring for long periods of time, so they can wait out a predator without issue.

In the event that a predator does see them, pottos are armed. They have a special set of vertebrae on their spines that extend slightly above the skin on their necks. Lowering this scapular shield is one of their last defenses against interested predators. Pottos tuck their heads under their shoulders and hope it will be enough to discourage an attacking predator. If predators don’t back down, a potto charges forward in an attempt to knock it off the branch.

Pottos move slowly and deliberately through the trees, most often crawling on top of branches rather than under them. Their special method of locomotion is made possible by pottos’ unique anatomy. Their fore- and hindlimbs are nearly equal in length, and their wrists and ankles are highly flexible. Their index fingers are significantly shorter than their other digits. Aided by their sturdy muscles, these adaptations enable pottos to hold themselves firmly upright as they move along, a phenomenon known as quadrumanous clambering.

Daily Life and Group Dynamics

Pottos spend most of their time alone. However, East African pottos have proven to be somewhat more social than other species. As mentioned, they never come together as groups since that would risk drawing too much attention to themselves. Instead, they keep quiet and hidden as often as possible. Neighboring males and females come together briefly to groom and mate but never linger longer than required. The relationship between mothers and their offspring is the only substantial long-term social contact pottos keep, which lasts only as long as her young remain dependent on her.

A mother East African potto wakes after dusk and sets out through the dark forest in search of food. She leaves her infant parked in the hidden place where the two spent the day sleeping. She keeps her large light-sensitive eyes peeled for tasty morsels, crawling slowly along branch by branch.

When she finds some fruit high up in the canopy, her errand is time-sensitive. Not wanting to linger too long in the open, she stuffs her expandable belly and retreats to the denser understory and shrub layer as fast as possible. Here, she puts her nose to a branch to sniff out nutritious insects hiding in foliage. She fills her stomach with whatever foods she comes across before returning to digest her meals and nurse her infant.

A male keeps the same routine as a female: waking at night, foraging until he is stuffed, and returning to the brush again to rest and digest before venturing off to find more food.

Fun Facts

In some English-speaking regions, pottos are called “softly-softlys.”

Some people says pottos have a very particular smell similar to curry.

Olingos and kinkajous are two creatures from the raccoon family who bear an uncanny resemblance to pottos.

Communication

Pottos might seem introverted to us humans—who tend to think of socializing as something overt and physical, and communication as something vocal and loud. Actually, pottos have simply developed other means to socialize and communicate that are a better fit for their cryptic lifestyles.

Large gatherings and boisterous vocalizations would draw far too much attention. Instead, pottos stay in touch with their neighbors through scent-marking. Glands underneath their stumpy tails secrete a special oil, which they rub on various substrates as they travel. By smelling these scent-markers, mating pairs keep tabs on one another, quietly strengthening their bonds over time.

Males also use glandular secretions and urine to mark their territories, warning rival males to stay out. When male pottos meet, their encounters are often heated.

While smell is pottos’ primary medium for communication, they also use other methods. For instance, during their heated altercations, male pottos make raspy whistles that probably signal their aggression. On a single occasion, an East African potto was observed making a series of loud and long whistles that lasted several seconds. The researcher who observed this event noted that it sounded unlike the typical whistles lorises and pottos are already known to make. Not only that, but the individual opened its mouth in order to make the whistle, a behavior never seen before in our study of these genera.

What could such a call mean, and what other curious vocalizations do pottos make that we have yet to hear? Only more research can tell us.

Reproduction and Family

Pottos are primarily social when it comes to mating and raising a family. A male potto’s territory overlaps with those of one or two females, suggesting they are a promiscuous or polygynous species. They keep in touch with each other through scent-marking. When the male meets one of these females in person, they often perform little rituals. They take turns grooming each other using their claws and teeth, and clean the other’s fur with their tongues. Typically, they also scent-mark each other. And they do all of this while hanging upside-down by their feet!

East African pottos mate once a year, but their breeding seasons vary regionally. It often works out that the baby pottos are born so that fruit is most abundant in the area just as the infants are ready to be weaned.

Following copulation, a mother is pregnant for about 200 days. For such a long gestation period, her newborn is tiny—weighing 1-2 ounces (30–52 grams)! Once in the world, however, the newborn potto’s physical development picks up pace: growing at an average rate of 1/10 of an ounce (3.19 g) per day!

Being so tiny, the newborn potto relies heavily on its mother. The baby climbs onto her belly and clings tightly to her fur for the first three to eight days. Eventually, her baby is big enough to leave alone. She parks her infant on a well-hidden tree branch while she goes off to forage each night. She returns during the day to nurse and sleep.

At three or four months, the newborn starts to accompany its mother during foraging excursions. Thus he begins to learn how to navigate the canopy as a potto. When he gets too far behind, he climbs onto his mother’s back. Between four and six months, the newborn is weaned—it depends on how quickly he learns to forage for himself. He practices by grabbing the food and prey his mother finds from her, and examining it with a head-cocking motion—as though memorizing it—before shoving it in his mouth. Eventually, he learns what sorts of things are edible and forages more and more on his own.

By month six, he knows enough to set off on his own. As a male, he disperses straightaway. Females, however, usually stay with their mothers until they are eight months old, even when they might know enough to make it on their own. When they disperse, females inherit part of their mother’s range. But it is not known to what extent the two pottos stay in contact.

East African potto. Photo Credit: © Yvonne A. de Jong/-iNaturalist/Creative Commons

Ecological Role

As frugivores, East African pottos likely disperse the seeds of the fruit tree species they consume. The seeds pass through their digestive systems while they travel, falling to the forest floor in their feces far from where they were consumed.

Since East African pottos are known to eat a number of insects other animals generally find unpalatable, they may help keep these species’ numbers under control. By drinking the nectar of certain flowers, pottos may help in their pollination. Only more research can shed light on these theories.

Conservation Status and Threats

The East African potto is classified as Least Concern by the International Union for Conservation of Nature (IUCN, 2017), appearing on the IUCN Red List of Threatened Species.

While “Least Concern” doesn’t sound all that threatening, it should in no way imply that East African pottos are fine. Their populations are in decline, with densities much lower across large areas than locally. Seeing how the status of primates can change rapidly, it is important that any threats to their existence are dealt with timely and effectively regardless of their status.

While East African pottos are listed as Least Concern, the Mount Kenya subspecies is listed as Critically Endangered and is possibly already extinct in the wild. If so, it is important to determine why this happened so that similar outcomes can be prevented in other areas where East African pottos roam. If Mount Kenya pottos are still alive in the wild, might their discovery be enough to inspire a new wave of conservation for pottos—especially if it turns out they are not a subspecies after all?

East African pottos are primarily threatened by habitat loss. Despite being a relatively adaptable species—even capable of subsisting in people’s gardens—their species cannot survive without the forests they rely on for food and camouflage. As humans develop the land, converting these forests into farmland in order to grow their settlements larger and larger, East African pottos will only become more and more vulnerable. Deprived of the dense foliage they need to stay hidden, they will only become easy targets for predators. How will they ever hope to escape when their arboreal habitat has been razed?

Even where forests are not clear-cut, roads and other forms of infrastructure fragment pottos’ territories. While these might seem like tiny and negligible developments to us humans who easily walk upright along the ground on two legs, arboreal species that rely on the canopy to get from place to place are doomed to be adversely affected by them. Especially for such a small primate that cannot leap, like the East African potto, any gap in the canopy is a potentially uncrossable obstacle. If a potto bothers to leave the canopy in order to cross a gap, it makes itself vulnerable to predators—its awkward movements along the ground only drawing that much more attention to it. If it needs to cross a street, then it can easily get hit by oncoming cars.

Over time, habitat fragmentation creates genetic bottlenecks. As their populations become isolated, gene flow screeches to a halt, and pottos find it harder and harder to mate with genetically diverse others. This has consequences not only on the number of offspring that are born but on their viability as well. In just a few generations, inbreeding leads to the development of debilitating deformities and heightened vulnerability to diseases and parasites, thus decreasing their chances to live into adulthood when they can mate and pass on their genes.

Deforestation and forest fragmentation also put East African pottos at odds with the very humans that destroy their habitats. Farmers and landowners may find pottos a nuisance, choosing to harm or kill them in order to protect their crops. Loggers generally cut down forests during the day when pottos are sleeping. Their slow movements, not to mention the tendency to freeze when in danger, means that such rudely awakened pottos are more than likely to go down with the tree. Even if the fall doesn’t kill them, they are less than likely to make it to any functional habitat before being found by predators.

Additionally, humans have long hunted pottos for their meat, and their body parts are often used in the Democratic Republic of Congo for traditional medicine and witchcraft. Locals that do not wish to eat them may still capture them to keep or sell as pets. As pets, primates only suffer. Primates forced to be pets lack the social stimulation they would have found in the wild. Pet owners rarely know what their captees need in terms of food, let alone how to provide it, dooming their charges to malnourishment and eventual death through starvation.

Nocturnal primates, like pottos, suffer in especially unique ways when kept as pets. They live in a constant state of threat. Not only does lack of proper habitat disable them from moving about freely, but the diurnal routine of their captors keeps them awake during the day, intensifying their stress. When the sun goes down, the lighting in their captor’s homes hurts their sensitive eyes.

Pottos rescued from the pet trade cannot simply return to their natural habitats like nothing happened. Primates taken from the wild are usually poached when they are still young and vulnerable. This means they never properly learned how to survive in the wild. Rehabilitating primates takes years of hard work, and there is never a guarantee that the time or efforts of conservationists will pay off in the end.

East African pottos are also threatened by human conflicts. Wars and social unrest waging in the countries where they are found put them regularly in harm’s way. Economic instability creates situations where local people are focused on their own survival and cannot be bothered to worry about a primate they know little about. Political upheaval in many areas where pottos live often makes enforcing protections difficult, if not impossible. While these problems persist, conserving East African pottos in the wild will remain tragically difficult.

Conservation Efforts

The East 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. This species is also classified as a Class B species under the African Convention of Conservation of Nature and Natural Resources. East African pottos are present in multiple protected areas throughout the species’ range.

Sadly, there are no conservation projects currently underway that focus on pottos specifically. A few organizations that deal with nocturnal primates more generally do perform some research into pottos, but for the most part this genus doesn’t get nearly as much attention as others.

Since going under everyone’s radar is kind of the whole point, there’s an unfortunate irony in just how little attention pottos receive from conservationists. Pottos have already proven to be more diverse than scientists originally imagined. What if their diversity is even more nuanced and each distinct species that much more precious and endangered? After all, it already turned out to be so with their slow loris cousins in Asia. Such information is also paramount when re-wilding rehabilitated primates, as they would need to be returned to precisely the right habitat and not any other.

References:

  • alltheworldsprimates.org
  • https://www.iucnredlist.org/species/136875/91996195
  • https://radar.brookes.ac.uk/radar/file/bea3a361-ea41-4428-a5f5-498f267a117e/1/176575-451410-1-SM.pdf
  • https://www.int-res.com/articles/esr_oa/n023p107.pdf
  • https://www.wildsolutions.nl/mount-kenya-potto-lost-subspecies/
  • https://animaldiversity.org/accounts/Perodicticus_potto/
  • https://www.researchgate.net/publication/228665534_Distribution_of_the_Potto_Perodicticus_pottoPrimates_Lorisidae_in_Eastern_Africa_with_a_Description_of_a_New_Subspecies_from_Mount_Kenya#pf22
  • http://static1.1.sqspcdn.com/static/f/1200343/27795193/1515432450133/PC31_Butynski_De_Jong_Perodicticus.pdf?token=GGyhSeEUsW83P63OIaRKuStHxgU%3D
  • https://animalia.bio/potto

Written by Zachary Lussier, March 2022