Scientific Latin name

Geographic Distribution and Habitat

Geladas are endemic to Ethiopia, meaning they are found here and nowhere else. It’s in this astounding, unique geography, shaped by millions of years of volcanic and tectonic temper, that geladas have made their last stand. Long ago, they, and other species from their genus, once roamed widely throughout Africa. Now these rarified heights are the last place in the world where you can find this extraordinary creature. 

Living at altitudes of up to 14,400 feet (4,400 meters), geladas are one of the highest-dwelling nonhuman primates. They can be found ranging from the alpine grasslands of the north to the south of Ethiopia where the yawning rift valley, nestled between shadowy and crinkled plateaus, tears at the continent’s seams, burping out fossils from a time when the ancestors of humans and geladas were even more intimately linked.  

Their highest populations, though, live in the north around the expansive highland meadows of Ethiopia’s Simien Mountains. Up here, the craggy mountain peaks and undulating plateaus fade into blue clouds. On clear days, the sun reveals sweeping gorges and steep basalt cliffs that formed 40 million years ago from the remnants of a great shield volcano. At these breezy heights, where temperatures range between 50°F (10°C) and 70°F (21°C), the wind sweeps grasslands of yellow, brown, and green, sparsely forested with shaggy junipers, shrubs, and the peculiar pointed lobelia trees.  

Between the northern and southern reaches of their range, gelada communities can also be found sprinkled in areas around Addis Ababa, Ethiopia’s sprawling capital. These include: Guassa, where the rugged mountains, crosscut by gorges, form the watershed between the Nile and the Awash river systems; the Wollo province, bound by rivers to its north, south, and west, and to the east by the escarpments that border the Afar desert lands; the terraced cliffs, canyons, and waterfalls of the Debre Libanos that feed into the Blue Nile; and the last remnant woods of the Wof-Washa Forest which is known locally as the “Cave of Birds”.  


Before we delve into the taxonomic tussle surrounding geladas, let’s get naming out of the way. If you found yourself among the Oromo-speakers of Ethiopia, with their beautiful beaded headbands, colorful clothes, and irresistible rhythms of life, you might hear the gelada referred to as jaldeessa daabee, an apt two-word description of our monkey: jaldeessa means “baboon” or “ape”, and daabee means “long hair”.

Another alter-ego for geladas could have been scribbled down by a poet: the “bleeding heart monkey”, referring to yet another descriptor of this unique creature: a shiny pink heart-shaped patch of skin on their chests.

The rest of the names for geladas are downright insensitive, and should only be whispered behind their backs so as not to insult them. Case in point: the name “gelada” itself. “Gelada”, a word coming from the Amharic language of Ethiopia’s Gonder region, means “ugly”. Let’s take a look at another one, their genus name: Theropithecus, from the Greek word “beast-ape”; hey, that’s not very nice! While geladas wouldn’t exactly hold a candle up next to Idris Elba or Gal Gadot in a competition of human attractiveness, to them, hairy backs, wacky hairdos, bizarrely elastic upper lips, and a chest that resembles a heart surgeon’s patchy job at coronary bypass surgery are the penultimate signs of hunkiness and attractiveness. Get to know them and, perhaps, you too may find them supremely beautiful. 

Throughout much of their history, geladas have been associated with baboons, and the Oromo aren’t the only ones to think so. Originally, scientists also called them “gelada baboons” or “bleeding heart baboons”. It’s not hard to see why! After all, a gelada looks a bit like a baboon in a poofy parka. But are these monkeys true baboons? That is, do they belong in a genus with baboons? It’s a question that’s had taxonomists and geneticists circling each other for decades.

As of 1979, geladas were placed in their own genus, Theropithecus, distinguishing them from true baboons in the genus Papio. This has been more firmly supported by genetic evidence showing the gelada’s genus, Theropithecus, split from a common ancestor of geladas and baboons long ago. In the interim between today and that distant branching from their common ancestor, the genus Theropithecus was filled with numerous fascinating species whose fossils can be found in what is now South Africa, Malawi, the Democratic Republic of the Congo, Tanzania, Uganda, Kenya, Algeria, Morocco, Spain, and in sites as far-flung as India. These include T. brumpti, a large-fanged monkey dwelling in riverine forests that ate leaves and cracked nuts with its teeth; T. oswaldi, a specialized grass-eater, like geladas, that existed alongside our ancient hominin ancestor Homo erectus who drove them to extinction; finally, there was the mysterious T. darti who ostensibly darted out of existence so quickly there’s not much to say about them. All of that is to say geladas are the remnants of an incredibly unique lineage that can just as easily be extinguished as their ancient cousins.  

Now, something should be said about subspecies. There are two of note: the northern gelada, T. g. gelada, and T. g. obscurus who reside to the south and east and are sometimes known as Heuglin’s gelada. Two key indicators between the subspecies are such: geladas in the southern regions have a shorter snout than those in the north, and geladas in the north have a larger and rounder skull than those in the east and south.

Gelada range, IUCN 2023

Size, Weight, and Lifespan

When it comes to geladas, males are significantly larger than their female counterparts, weighing up to 44 pounds (20 kg) and standing 29 inches (74 cm) tall compared to females who weigh around 31 pounds (14kg) and stand 24 inches (60 cm) tall. In the world of zoology, this difference between males and females is called “sexual dimorphism”. 

In the wild, geladas live to be about 15 years old, but nearly double their lifespan in captivity.


It’s no secret, geladas love grass. In fact, it’s practically the only thing on their menu, along with grass seeds and, well…more grass. They love it so much, one might think they sprouted it from their backs like some peculiar Chia Pet. What does a gelada look like? A lot like the tufted mounds of gold-straw-brown grass blowing in the Simien mountain breeze. Particularly the males who have a great bizarro mane of hair that descends into a shaggy cape along their back. All this hair makes them look like a peculiar mix between the lion in The Wizard of Oz and everyone’s great-aunt Ethel in her fur hat. Beneath that fuzzy mane are two pink eyebrows seated above flickering golden eyes and a wrinkled dark brown face that protrudes in a snout. 

When threatened, their elastic upper lip curls back over this snout revealing a pink patch of gums and two sharp teeth. The rest of their teeth are a threat only to grass and the occasional insect or tuber. In fact, geladas’ teeth are so adept at munching grass, they have the chewing efficiency of a zebra. 

Geladas are called bleeding heart monkeys on account of a shiny patch of skin on their chests that resembles an inverted heart. Aw. Females have them, but not as vibrantly as the males do. During estrus, the female’s heart-shaped patch brightens and grows a “necklace” of fluid-filled blisters that the male gelada finds simply irresistible. But wait a second, is that heart-shaped patch really even heart-shaped? Whoever came up with that name must not have looked very closely. Further examination reveals an hourglass. The inverted heart’s tip spreads out into a fleshy red turtleneck beneath the chin. 

Around their rump, geladas have a thick layer of callouses over a layer of fat. These are known as “ischial callosities” and are reinforced patches of skin, often pink in color, that, as we will see, are an essential adaptation to their posture while grazing.   

Above this butt pad, geladas have a long, slender tail that adds significant length to the body. For males, the tail can add between 17 and 20 inches (45-50 cm) to their body length. Females, on the other hand, may have tails within the range of 11 to 16 inches (30 – 41 cm). At the end of these tails is a tuft of fur.  


Geladas spend a lot of their time grazing, ten hours a day in fact! And, grass— festuca grass to be specific—its seeds and a variety of sedges make up a staggering 90 percent of their calories. In scientific terms, this means they’re “graminivores” or grasseaters. What is the other ten percent of their diet? A smorgasbord of roots, flowers, and the occasional insect. But this deviation from the grass menu mainly occurs in the dry season.

Come dry season, the underground storage organs of plants are a rich source of carbohydrates and water. These storage organs can include tuberous roots, bulbs, and modified stems. Typically plants project these storage organs into the soil to prevent herbivores from finding them, but they’re no match for the gelada. This is partially thanks to the fact that evolution equipped geladas with some unique physical features that help them more readily harvest grasses. For one, they employ an ingenious energy-saving evolutionary technique: the shuffle gait, a unique method of movement that allows geladas to keep low to the ground, essentially scooting along on their padded butts. They then use their short stubby fingers, perfectly shaped for the task, to pluck at grass blades and dig for tubers.  

The only thing wrong with grass? It isn’t particularly nutritious. Well, that’s not exactly true. Grass is nutritious; it has all the proteins, fiber, lipids, water-soluble carbohydrates, minerals, and vitamins one needs for life, but it’s… a little hard on the stomach. This is thanks to one pesky feature: cellulose. Cellulose is a complex carbohydrate that gives grass its structure and strength. That’s great for bouncing back after some water buffalo trods on it, but when it comes to animals breaking it down in their digestive tracts, it can be difficult for many species, including us humans. For many primates, grass is pretty indigestible, but over about 23 million years of evolution, geladas have nurtured a special relationship with it, or should I say their guts have. 

In practically every way, the gelada intestinal tract is about the same as any other primate’s, except for one easily overlooked detail, or should I say trillions: their gut microbiota. Like all living organisms with digestive tracts, geladas harbor colonies of symbiotic microorganisms in their intestines. This can include a hodgepodge of bacteria, archaea, protists, and even fungi and viruses that, together, assist with the breakdown of food. The composition and function of these gut microbiota can differ widely from animal to animal, meaning they’re highly coevolved to specific lifestyles. In the case of geladas, their gut lining is composed of predominantly three phyla of microbiota including Bacteroidetes (44.5%), Firmicutes (34.6%), and Spirochaetes (4.5%). These percentages vary slightly from season to season and between different reproductive units. Importantly, all three of these groups of microbiota are experts at breaking down cellulose through a fermentation process in the hindgut. 

But, even with the help of these microbes, it’s a tough life being reliant on grass. To assist their tiny workforce with breakdown, geladas have evolved enlarged molars and reduced incisors that help grind the grass down before digestion. But, at the end of the day, even with all this help, grass as a whole provides scant nutrients to geladas. As a result, they must forage longer hours than the typical primate just to meet their nutritional requirements. This has an impact on their work-life balance, namely the amount of time dedicated to social grooming, an activity usually valued among primate troops because it enhances social bonds. But, alas, the gelada must sacrifice for the thing he or she loves.

Behavior and Lifestyle

Being a diurnal species, geladas spend most of the daylight hours foraging. At dawn, they awake upon the sleeping cliffs, stretching, and spending a small amount of time grooming and sunning themselves. Then it’s off to the grasslands to forage. Throughout the day geladas move with a combination of quadrupedalism, meaning they walk on all fours, and a “shuffle gait”, which is used primarily when feeding. While the “shuffle gait” sounds like the latest TikTok dance, it’s actually a unique method of movement that allows geladas to keep low to the ground. To do the shuffle gait they squat on their hind legs, then move along, plucking grasses, without changing their posture. If it weren’t for hairless pads of calluses on their rear, known to science as “ischial callosities”, the shuffle gait would be a real pain in the butt—literally. Instead, these butt pads provide comfort and prevent soreness during long periods of sitting and scooting.   

While geladas have long tails, they aren’t prehensile, meaning they’re incapable of grasping or holding objects like branches. Instead, these tails are primarily used for balance, especially when cliff climbing, and communication. Geladas don’t spend much time in trees. In fact, they are the world’s most terrestrial primate species, aside from humans. The only time they are caught in a tree is during sentry duty. If a predator is spotted, they release an alarm cry causing the grazing geladas to gather together and flee towards their sleeping cliffs. 

Geladas aren’t the only hungry ones out in the Ethiopian mountains. These cliffs act as strongholds from predators both during the day and through the perilous night. When they’re not collecting grass, those strong stubby fingers are excellent for rock climbing. On the narrow shelves of these cliffs, geladas spend the night huddling closely together. And for good reason; in this case, there actually is something scary beneath their bed. Hyenas have been known to lay in wait beneath the cliffs where geladas sleep in hopes one will fall. And, hyenas aren’t the only ones hoping to turn a gelada into a tasty morsel. Life in these mountains can be precarious. Lone leopards wait in hidden viewsheds, servals slink silently through the brush, clever jackals and foxes plot to carry off the young and sick, packs of wild domestic dogs prowl, and birds of prey cast their shadows from above. Geladas must always stay vigilant. 

Fun Facts

Amazingly, geladas have developed a commensal relationship with Ethiopian wolves, allowing them to trot about their herd without so much as batting a pink eyelid. The wolves brush past baby geladas without so much as a sniff, preferring instead to devour rodents that are easier to catch in the geladas’ presence. Among the gelada herd, wolves have a hunting success rate of 67 percent compared to just 25 percent outside of the herd. To some, this conjures images of human’s early relationship with wolves who would eventually be domesticated into dogs. But don’t think geladas are going to be breeding Schnauzers anytime soon. They have a healthy distaste for domesticated dogs who they flee from upon first sight. This is because domesticated dogs in the Ethiopian highlands are much more likely to prey upon geladas than any wolf. Geladas benefit from this relationship with wolves by having one less predator to worry about in the Ethiopian heights.

Daily Life and Group Dynamics

The Levels of Gelada Society

Gelada society throughout the Ethiopian mountains is multilayered and dynamic. At its most reductionary level, it consists of two types of fundamental “blocks” or “units”. The most common is the “reproductive unit” or “harem”. These units consist of a dominant female elder, her close female kin (usually one to twelve females), their offspring, a dominant male leader, and occasionally a few “subordinate” or “follower” males. The second type of unit is the “all-male” or “bachelor” unit. These consist of anywhere between two and fifteen males. As we will see, these all-male groups can play a crucial role in the genetic diversity of a reproductive unit and have a significant effect on the power dynamics of life in the Ethiopian Highlands. 

Expanding our scope outwards, the next largest strata of gelada society is called the “band”. But don’t expect to see any geladas holding trumpets or glockenspiels. This band is composed of somewhere between two to about twenty-seven reproductive units and several all-male units. The band members generally sleep and forage within close range of each other. You can also think of the “band” as an “ecological unit”. Since the gathering of units in a band is concentrated within a geographical home range, they influence the distribution of resources and other species within that ecosystem, such as predators, availability, and functionality of grass, roots, rhizomes, and tubers. Part of the benefit of a band over a single unit is greater strength in numbers. Higher numbers mean there are more eyes to look out for predators or available food patches.    

Bands typically share overlapping home ranges with between one and four other bands. These overlapping groups compose a “community”. Communities are less tightly knit than bands with members of the same community associating less than 50 percent of the time whereas units in the same band interact more than 50 percent of the time. The interactions between bands within a community allow for a unique type of fission-fusion to occur. Essentially, “fission-fusion” refers to a type of social organization where the composition of a group changes as individuals move in or out of the “band” or “unit”. Fission, or the splitting of a group, can occur for a number of reasons including a change in food availability or conflicts within a group. These community gatherings can provide a vital opportunity for young males to take over or join reproductive units.  

Finally, you have the “herd” which is made up of about sixty reproductive units that are sometimes from different bands. When herds come together they can be as large as a thousand individuals or more. Woah, that’s a whole lotta geladas. 

Life in the Reproductive and Bachelor Units

For most geladas, social life typically revolves around what’s called the “reproductive unit” or “harem”. Even the fiery adolescent geladas from the bachelor units have their lusty eyes on these groups. The most consistent members of the “reproductive unit” are the females. A dominant female holds the most sway over the social decisions of the unit. The other females and young look to her when it comes time to move the unit to grazing grounds. She tends to be the eldest and has no doubt seen the rise and fall of a few dominant males in the unit in her lifetime. 

While the dominant male will mate with multiple females in the harem, the dominant female will frequently monopolize sexual access to him. This means that she, and occasionally other high-ranking females (closely related to her), will bear the most offspring with him. To be sure, there’s a pecking order. Geladas interact at most with only three other members of the unit. While aggression within a unit tends to be rare, when it does occur, it typically happens between females. 

This dominant male or “harem master”, as some call him, has the reddest chest patch of all the males. The more females he has in his harem the redder his chest becomes so that harem masters with many females (~12) have redder chests than those with less. This colored trait advertises his virility to females and may also serve as a warning signal to rival males. 

It’s thought this red patch serves as a signal to ward off rival males and predators. One day the resident male will be supplanted by a rival male. Until then he must stay vigilant, keeping an eye on those all-male units patrolling the outskirts of his territory. In this zero-sum game of mating, you’re either leading a harem or struggling for access to reproductive females. But this struggle for access can occur in a variety of ways, and gelada males employ a range of strategies to accomplish this. 

Occasionally, unrelated males, known as “follower” or “subordinate” males, will join reproductive units, though this means they’ll abstain from mating for some time (or so it appears) since only the dominant male may mate with the females in the harem. These males act as the group’s babysitters or coalitionary backups should the unit be invaded by rivals. 

Some of these subordinates are unsuccessful rivals; others have left their reproductive unit only to return; others, still, prefer to employ a different reproductive strategy other than taking over a harem. While subordinate males are not supposed to mate with any females in the harem, they often do when the dominant male’s back is turned. In fact, about 17 percent of a unit’s offspring are fathered by subordinate males. Not such a bad strategy after all. Interestingly, when this occurs, both the female and the subordinate male suppress their typically loud mating cries, suggesting they don’t want to be overheard. This is one example of cheating and fear of discovery being observed in wild animals. 

While female geladas stay in a reproductive unit for life, young male geladas typically only remain for four or five years on average and then venture out to start their own unit. This happens in a few different ways: a few simply return to the reproductive unit in which they were raised; others will go off and join another reproductive unit as subordinate males with the dream of breaking off into their own reproductive unit when the females number more than twelve; and, lastly, some will gather their peers and create an all-male unit with the intention of toppling a dominant male leader from his harem. As it turns out, which path an individual takes depends a lot on the social environment in which he was raised.

Juvenile males that form these all-male units are typically the offspring of nondominant mothers. Their blood is surging with androgens, hormones that are associated with male secondary sexual characteristics. While, in pop wisdom, androgens, like testosterone, are associated with aggression, it’s important to note that they don’t actually cause aggression. Rather they amplify pre-existing aggression. They also make the hard things—such as hand-to-hand or tooth-to-tooth combat— easier, even pleasurable, to do. These males typically leave their units earlier than the others, often bringing with them male peers of their own age. That said, these all-male units will have just one dominant leader. In contrast to this group, juvenile males with high-ranking mothers tend to have lower androgen levels. Interestingly, it’s thought that the resources available to the growing juvenile male via its mother’s rank are what determines the androgen levels and pace of their development.

When a rival male topples a dominant male he then looks to the dominant female for acceptance into the group. That’s because when it comes to reproductive units, sure the male draws attention with his flashy chest and tufted cape, but it’s the dominant female who is actually calling the shots. The others in the troop, mostly her close relatives, look to her for decisions, including the acceptance of a new harem master. Should the residing male falter or show weakness in a fight, she will most likely accept the stronger rival. After all, she wants the best for her family, and a male must be able to fend off predators and dangerous intruders. Sometimes the residing male will even fight to his death. With a female leader, this powerful diplomacy takes a gentle touch. Rather than rule by force (as is the case with the gelada’s close relative, the hamadryas baboon), the dominant male grooms the dominant female, making sure she’s content enough to support him when a rival male comes roaming around.


Geladas are extremely vocal, employing a large range of vocalizations including wobbles, grunts, groans, and squeals. Since foraging takes up so much of their time, ten to twelve hours by some estimates, there isn’t much time for social activities like grooming. It’s all scooting and scuttlebutt. So to keep up with the social hoopla, geladas employ a range of 30 different vocalizations when in the vicinity of one another. These sounds can confirm close contact, reassure others of safety, appease dominants, solicit others, convey ambivalence, front aggression, or act in one’s own defense. 

But it’s not only the apparent meaning behind these wobbles, grunts, groans, and squeals that are interesting; geladas will string these sounds together with contextually dependent length and complexity. When combined with the elasticity of their lip movements, these strung-together vocalizations sound suspiciously like sentences, making gelada communication the closest equivalent to human speech in the natural world. To give you an idea of the complexity, consider the relationship between sound, complexity, duration, and situation. Here are some examples: while in the herd, geladas increase the number of longer and complex sound sequences so as not to be interrupted by the surrounding tittle-tattle; when they risk separation from one another, the sounds grow longer but not more complex; and when a male and female interact, the sound sequence become much more complex.

Reproduction and Family

A gelada family consists of one dominant male, one dominant female, several females that are closely related to the dominant female, and all their offspring.

It’s the dominant male’s duty to protect the unit from external threats. To maintain his position, the dominant male must use his strength and aggression against predators, rival males, and occasionally subordinate males if the circumstances call for it. As a reward, he is given exclusive mating rights with the females of the unit, though, in reality, the dominant female and her closest kin monopolize the mating. More distantly related females are aware that this dominant female calls the shots and will go so far as to ignore the dominant male if he attempts to mate with them. 

Females reach sexual maturity around the age of four and signal their readiness to mate by developing a distinctive necklace of red, pus-filled blisters on their chest during estrus. These are produced by fluctuations in hormone levels and occur during the most fertile phase of her reproductive cycle. It is a crucial visual signal that facilitates mating with the dominant male. Upon seeing it, a ritual ensues. The dominant male will approach a sexually receptive female and inspect her blisters and genitals. If all seems satisfactory, they will mate. 

After a gestation period of approximately six months, the female gives birth to a single offspring. Newborn geladas are small, weighing roughly 16 ounces (460g), and have black fur, closed eyes, and a red face. They are typically born at night. There are a couple of reasons why this might be. One is that the cover of night offers a level of protection to the baby and mother. Another is that it allows the mother and newborn to rest and recover during the quiet hours of the night before interacting with the rest of the group during the day. One assumes that these well-timed births have an intricate relationship with the mother’s circadian rhythm, though the exact mechanism is not yet known. After birth, the mother carries the infant for the first five weeks of its life, after which it is strong enough to be transported on her back.

As the years pass, the dynamics within the gelada unit can change dramatically. Dominant males can be challenged by rival males, leading to violent confrontations. If the outsider is victorious, he takes over the unit and becomes the new leader. This can trigger a surge in prolactin levels in the females, leading to self-induced abortion of any offspring sired by the previous leader, a phenomenon known as the ‘Bruce Effect’. Believe it or not, this is actually a protective measure taken by the mother. It prevents her from birthing a baby that may be killed by the new dominant male. Infanticide is a real risk for female geladas whose unit is overtaken by a rival male. It’s thought that around 60 percent of all infant mortality is due to infanticide. As a result, roughly 80 percent of pregnancies are terminated in the weeks after a dominant male is replaced as a measure to prevent this. 

While at first glance it might seem cruel when pitted against our human sensibilities, the natural world often operates by a necessary and practical calculus of resources and genetic reproduction: kill or be killed, pass ones genes down, or risk them vanishing forever. When it comes to reproduction, time and resources are of the essence. After all, females give birth to one infant at a time and reproduce only once every two years. That is a long time to wait for a new rival male. During the period after pregnancy in which infants are nursing, female geladas won’t be fertile. Their reproductive system is still recovering from pregnancy, preventing ovulation from occurring. Killing the infants of a previously dominant male renders the females sexually receptive again.  This allows the new resident male to sire his own offspring and spread his own genes. Interestingly though, infanticide is a choice not made by all males. While not enough is yet known about this, it is thought that some degree of “personality” comes into play regarding this choice. 

Despite these upheavals, gelada family life is characterized by strong social bonds and cooperative behavior. Adult females and their female offspring often remain together for life, forming the core of the unit. Meanwhile, young males leave the unit upon reaching puberty to start this cycle of reproductive unit upheaval somewhere else.

Ecological Role

Geladas are deeply entrenched within the unique ecosystems of the Simien mountains. As gelada herds comb through the grasslands plucking blades of grass and scrabbling through the dirt for seeds and tubers, they aerate the soil, bringing rich oxygen to the roots of the grass. It is a relationship millions of years in the making. Not only do they rejuvenate the soil, but all this grass-munching provides an ecologically important clean-up service: cut down the dry grasses and reduce the risk of wildfires. As the world heats up to dangerous levels, this becomes an increasingly more important ecological service.    

Conservation Status and Threats

In the 1970s, about 500,000 geladas existed in the wild. That number is currently thought to be about 200,000, though official surveys still need to be conducted. Despite this significant drop, the International Union for Conservation of Nature lists geladas as Least Concern (IUCN 2018), appearing on the IUCN’s Red List of Threatened Species. They cited a “large range” and large extant populations as reasons for this status. Even so, there remains a foreboding forecast for the future of geladas. As the earth continues to warm due to climate change, the grassy highlands of Ethiopia are becoming less hospitable to gelada monkeys. Under the current climate, the suitable habitat for geladas covers approximately 35,093 square miles (90,891 square kilometers). However, species distribution modeling has shown that by 2050 this habitat is expected to decrease by 36 percent, and by 2070 to 52 percent. 

Part of this is due to encroaching human activity. Already, agriculture and developments have begun to impinge on gelada territory, and, along with it, comes deforestation and soil erosion. As the fifth fastest-growing economy in the world, Ethiopia’s population is burgeoning, increasing by 54 million people in just twenty years. As a result, more people are moving into the Ethiopian Highlands, converting the geladas’ home ranges into farmland and pastures for cows and goats. This competition with livestock for grass has pushed geladas onto gorge slopes where the grass they depend on is less productive. As a result, geladas are known to raid farmers’ crops and the pasturelands, producing friction between these monkeys and the farmers who are trying to make a living. Farmers will shoot geladas with guns or sick hunting dogs on them to prevent them from raiding their crops.

And, the human-gelada friction is only projected to get worse. Already, geladas are considered to be a “refugee species”, having been driven into higher altitudes by past human pressures. The higher altitudes traditionally have offered less competition with humans due to the poor soil and climate for agricultural yield. But this is changing. As the climate shifts, the lowlands will receive less rain, producing droughts that negatively affect crop yields, potentially impacting water and food security in the region. Decreased stream flows, declining groundwater levels, drying springs, and the siltation of lakes will likely drive more people into the cooler highlands where elevations that were previously difficult or impossible to grow crops and maintain livestock are predicted to improve with the warming climate.     

Other types of hunting also affect geladas. In the past, gelada males faced selective pressure as they were hunted and poached for their capes of hair which are traditionally used as costumes in Oromo coming-of-age ceremonies. There are also historical records of gelada capes being made into fur hats for tourists. In addition, government-sanctioned trophy hunting by tourists is allowed in certain regions. It is not currently known how many geladas are killed each year for these purposes. 

Aside from human threats, gelada populations are also impacted by tapeworms. These tapeworms form large protuberant cysts that, with their high mortality rate, impact a gelada’s ability to survive and reproduce.  

Conservation Efforts

While it still occurs in areas where the law can’t be enforced, hunting and trapping of geladas is expressly forbidden unless permitted by the government in the name of science or national interest. The Ethiopian government and conservation organizations have identified conservation sites across the gelada’s entire home range. And, when it comes to human-gelada relationships, it’s not all doom and gloom. It is possible for humans and geladas to cohabitate, even with increased pressure from humans. For one, the gelada benefits from sharing its territory with the Ethiopian wolf and the mountain nyala (spiral-horned antelopes). These species add to the Simien Mountains allure as an ecotourism destination, helping local populations reduce their dependence on subsistence farming and increase revenue for their communities. Organizations like the African Wildlife Foundation have been working together with local communities to plan and implement sustainable land use that allows both humans and wildlife to cohabitate successfully.  

The Simien Mountain National Park (SMNP) region offered the largest sanctuary for gelada populations. It has been featured on a number of high-profile documentary series, such as the BBC’s Human Planet and National Geographic’s Queens. The park and its surrounding regions are thought to hold around 4,260-4,560 geladas and can currently support a stable population. Out of 200,000 geladas, though, this park protects only a small number of these amazing creatures. Two other sites have been proposed for protecting geladas: Blue Nile Gorges National Park and Indeltu (Shebelle) Gorge Reserve.  

At the heart of gelada conservation is the need to understand how they are intertwined in the local ecology and to balance their needs with the needs of local people. Their conservation hinges on our ability to both appreciate their unique beauty and intrinsic value and to provide solutions for human-gelada coexistence. Assisting local communities in their conservation efforts is crucial to their survival, as these communities are often the stewards of the habitats where they reside. By fostering a sense of shared responsibility and appreciation, both nationally and internationally, we can ensure the preservation of geladas for future generations to marvel at and learn from. While currently listed as Least Concern, a time might come when the future of geladas lies in the balance, reliant on our capacity and our willingness to safeguard the natural world.  

  • African Wildlife Foundation. (n.d.). Gelada. Retrieved April 12, 2024, from
  • (n.d.). Gelada – Facts, Diet, Habitat & Pictures on Retrieved April 4, 2024, from
  • Ahmed, A.S., Chala, D., Kufa, C.A. et al. Potential changes in the extent of suitable habitats for geladas (Theropithecus gelada) in the Anthropocene.BMC Ecol Evo 23, 65 (2023).
  • Ahmed Seid Ahmed, Krishnagouda Shankargouda Goudar, Hussein Ibrahim Seid, Gelada (Theropithecus gelada) in Yegof National Forest Priority Area, Northern Ethiopia: Population structure, activity budget and local community’s perception towards its conservation, Global Ecology and Conservation, Volume 34, 2022, e02041, ISSN 2351-9894,
  • Ankel-Simons F. (2007). Primate Anatomy: an introduction, (3rd edition), San Diego: Elsevier Academic Press.
  • Bergman, T.J., Ho, L. & Beehner, J.C. Chest Color and Social Status in Male Geladas (Theropithecus gelada). Int J Primatol 30, 791–806 (2009). 
  • Bing Lin;  Iris R Foxfoot;  Carrie M Miller;  Vivek V Venkatamaran;  Jeffrey T Kerby; Emily K Bechtold;  Bryce S Kellogg;  Nga Nguyen;  Peter J Fashing;  “Leopard Predation on Gelada Monkeys at Guassa, Ethiopia”,   AMERICAN JOURNAL OF PRIMATOLOGY,  2020.  (IF: 3)
  • Dunbar RIM. (1986). “The social ecology of gelada baboons”, In: Ecological aspects of social evolution: birds and mammals, Rubenstein DI, Wrangham RW, (eds), Princeton (NJ): Princeton University Press pp. 332–51.
  • Gippoliti, S. & Hunter, C. (2008). “Theropithecus gelada”. The IUCN Red List of Threatened Species. 2008: e.T21744A9316114. doi:10.2305/IUCN.UK.2008.RLTS.T21744A9316114.en
  • Gustison, M.L., Tinsley Johnson, E., Beehner, J.C. et al. The social functions of complex vocal sequences in wild geladas. Behav Ecol Sociobiol 73, 14 (2019).
  • Holmes, B. (2015, June 5). Monkeys’ cosy alliance with wolves looks like domestication. New Scientist. Retrieved April 12, 2024, from
  • Jarvey, J.C., Low, B.S., Pappano, D.J. et al. Graminivory and Fallback Foods: Annual Diet Profile of Geladas (Theropithecus gelada) Living in the Simien Mountains National Park, Ethiopia. Int J Primatol 39, 105–126 (2018). 
  • Jablonski, Nina G.; Leakey, Meave G.; Klarey, Christopher; Antón, Mauricio (December 2002). “A New Skeleton of Theropithecus brumpti (Primates: Cercopithecidae) from Lomekwi, West Turkana, Kenya”. Journal of Human Evolution. 43 (6): 887–923. doi:10.1006/jhev.2002.0607. PMID 12473488.
  • National Geographic. (n.d.). Gelada. Retrieved April 12, 2024, from
  • PIN Factsheet – Gelada Baboon. (n.d.). Retrieved April 8, 2024, from
  • San Diego Zoo Global Library. (n.d.). Gelada Population & Conservation. Retrieved April 12, 2024, from []
  • Sen, S. (2023). Dispersal and reproductive strategies in wild male geladas (Theropithecus Gelada) (Unpublished doctoral dissertation). University of Michigan
  • Shipman, Pat; Bosler, Wendy (June 1981). “Butchering of Giant Geladas at an Acheulian Site”. Current Anthropology. 22: 257–288. doi:10.1086/202663. JSTOR 2742201. S2CID 87006937– via JSTOR.
  • Trosvik, P., de Muinck, E.J., Rueness, E.K. et al. Multilevel social structure and diet shape the gut microbiota of the gelada monkey, the only grazing primate. Microbiome 6, 84 (2018).
  • Turner, Alan; Antón,Mauricio (2004). Evolving Eden, An Illustrated Guide to the Evolution of the African Large-Mammal Fauna. New York: Columbia University Press. p. 55.
  • Van der Merwe, et al., 2003. The carbon isotope ecology and diet of Australopithecus africanus at Sterkfontein, South Africa. Journal of Human Evolution 44: 581-597.
  • Welch, C. (2019, March 28). Tough-looking gelada monkeys eke out a living at 11,000 feet in Ethiopia. National Geographic. Retrieved April 12, 2024, from
  • WeForest. (n.d.). Wof Washa Forest. Retrieved April 12, 2024, from

Written by Breton Worthington, April 2024