“BRAVEHEART ON THE EDGE” by Chadden Hunter
Article written for BBC Wildlife Magazine (September 2000 issue)
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GELADA FACTS:
· Geladas (along with madrills) are commonly classified as baboons, though ‘baboon’ is not an official taxonomic class and is often considered to include only species within the Papio genus.
· Geladas have the most complex vocalisations of any old world monkey, with more than 30 distinct calls, half of which are purely social. The frequency range of their vocalisations almost exactly matches that of humans.
· Gelada ‘bands’ (groups of family units that forage together and share the Ivane home range) can number up to 300 individuals. Different ‘bands’ often join to form ‘herds’, sometimes numbering more than 800 – the largest regularly occurring groups of any non-human primate.
· Female geladas reach sexual maturity at four years of age and give birth at the relatively slow rate of one infant every two years. Adults live 15 to 20 years.
· The current world population of gelada is estimated to be between 100,000-200,000, but subpopulations are isolated, and the species is listed by the United States Endangered Species Act (USESA) as ‘Threatened’.
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Braveheart has a problem. He has seven ‘wives’ and none of them are happy.
While I sit and watch the females of his family (‘unit J4’) looking after the infants, finding food and defending their sisters, Braveheart is sprawled out on the grass, asleep. This type of behaviour might not be a problem for many other male primates, but Braveheart is a gelada baboon, a species whose matriarchal social system demands a higher level of domestic input from males.
Theropithecus gelada is an unusual relative of baboons (Papio spp.) and the only living species in its genus. Around three million years ago, Theropithecus was a very successful group of graminivorous (grass-eating) primates that inhabited most of Africa and included species weighing up to 90 kg. Perhaps their size – and food requirements - contributed to their downfall, as they tried to cope with climate change as climate change and increased competition from larger brained hominids and Papio baboons. Gelada are the last relict of that great dynasty and are restricted to remote pockets of the Ethiopian highlands between 1700 and 4200 metres – the only place where the grass and herb layer is rich enough to meet the gelada’s specialised dietary requirements.
The uniqueness of the gelada’s ecology is matched by one of the most complex social organisations of any non-human primate. Gelada mothers, daughters and sisters form close family units, choosing unrelated adult males to reproduce with. Family units are the basic building blocks of the social system and commonly consist of four to five adult females and their young, making Braveheart’s family of seven unusually large. But what the males lacks in social power, they make up for in looks.
A male gelada is a magnificent animal. His hands are covered in shiny black fur, like velvet gloves, and his black rounded muzzle and deep brow are more akin to an ape’s face than a baboon’s. The top lip is often curled back over the nose in a gesture of threat, revealing a pair of menacingly large canines. About twice the size of a female, the male sports an impressive mane of silky hair that shimmers in hues of gold and chocolate. This cape of hair is over 40 cm long and so fine that a slight breeze can lift it into delicate a wave. No occasion seems inappropriate for showing it off, as male geladas can often be seen galloping across the highlands with their mane bouncing majestically on the wind; chased by a gaggle of irate, screeching females. For while Braveheart might have the physical edge one on one, he is no match for the solidarity of a female alliance.
These fascinating little soap-operas are being played out in a scene I can only describe as awe-inspiring. Thanks to mass media in the 1980s, many people wrongly imagine Ethiopia to be covered in deserts and famine. While these do exist in some parts, most of the country is actually lush highlands, once covered in temperate forests, herbs and giant heather trees draped in lichen. Unfortunately, very little remains of the giant heather forests and the herb layer on which the gelada depend, and they must now compete with the livestock and cultivation of a burgeoning human population.
The highlands are dissected by enormous gorges, pinnacles and escarpments reminiscent of Grand Canyon or Monument Valley, from where waterfalls plummet 500 metres to the lowlands below. The gelada use these treacherously sheer cliffs as sleeping sites to avoid predators such as leopards, hyenas and jackals. And nowhere are the cliffs higher than where Braveheart lives, along the mighty Simien escarpment in northern Ethiopia. For the last three years I’ve been fortunate enough to be based in the Simien Mts National Park (a tragically mismanaged World Heritage Site) studying these extraordinary primates. While I barely have the courage to crawl up to edge of the Simien escarpment on my belly and dangle my nose over, these rock-climbing wizards casually tumble over at sunset, fighting and playing on the way - as if there wasn’t a one kilometre drop-off beneath them! Once each family has found a sleeping ledge, no wider than a monkeys bottom, they cling together and brave a night of howling winds and sub-zero temperatures. Sleet, thunder, hailstorms and thick fog for weeks on end are commonplace in the Simiens. Gelada truly are the Hard-Men of the money world. It’s usually around this time of evening, after a long day of field research on the geladas, that I stagger back through the freezing gale to my remote, 3500m high hut at and dream of becoming an accountant in a warm office.
In the morning the gelada clamber back up onto the plateau and relax into sunbathing and socialising. The family stays close together while social bonds are cemented. Chelsea grooming her sister Suzy grooming her daughter Katy, like a massage chain, while the infants wrestle and play King-of-the-Castle in a giant heather tree. The only member of this family who rates a sleep-in above family bonding is Braveheart. I’m beginning to think more of him as the Homer Simpson of the monkey world.
Throughout the morning families gradually come together and form herds that often number over 600. As if the scenery wasn’t spectacular enough, the sight of such a large primate congregation on an alpine meadow is astonishing (although I must admit it is a nightmare for research when you’re trying to find specific individuals!). But the similarity to herds of wildebeest on the open plains does not end there. Gelada are unique in being the only primate with a diet made up almost exclusively of grass. To survive on such a poor diet they possess massive molar teeth specialised for grinding the nutrients out of grass and must spend more time feeding than any other primate.
This has lead to another quirky gelada characteristic. While most primate species display their sexual state on their rear (e.g. the swollen pink bottoms of fertile female chimps), gelada spend so much of their time sitting in order to pluck grass that their sexual display has shifted to the chest. Both males and females have an hour-glass shaped patch of bare pink skin on their chest which changes colour and condition with fluctuations in hormone levels. Once a month, when females are in oestrus the patch becomes more radiant and the edges bubble like blisters. Particularly virile males, such as Braveheart with his seven “wives”, have chest patches of such deep red that one common name for the gelada is the bleeding heart monkey.
Another adaptation to such a specialised diet of grasses can be seen in the gelada’s hands. They have short strong digits with tough fingernails for digging, and exhibit the highest opposability (the ability to touch fingertips to thumb) of any non-human primate. This gives them the dexterity they need to pluck individual grass blades and seeds fast enough to survive on a high volume, low nutrient diet. Indeed, they often feed at a rate so fast I could only measure it using slowed down replays from a video recorder.
It’s no wonder that families often fight over particularly juicy patches of preferred herbs. On one such occasion I went to see what all the fuss was about and discovered the gelada were eating thyme. After taking a plant Sample for later nutritional analysis made the follow-up discovery that it did wonders for my bolognase sauce in camp.
Within each family the heirachy of females is normally well established. If Braveheart’s alpha female, Chelsea, wants the patch of grass her younger sister, Suzannah, is feeding on, Suzannah is quick to get out of the way. More serious fights over prime feeding patches are started by females in rival families where sisters will defend each other ferociously. Chelsea with her sisters and daughters holds a distinct advantage here as larger families usually come out on top. They will also expect their family male to come to their aid. During agonistic encounters between two family units, the two opposing family males, often having no idea what the squabble is about, come face to face and attempt some form of conflict resolution. You might be surprised, but the males in this species are actually pretty good at it. If the family male doesn’t help defend the females he can expect anything from domestic hell to loss of sexual privileges. Males toe the line.
Braveheart, however, is on shaky ground. Our research suggests that gelada males will struggle to remain “Lord of the Manor” when their families extend beyond about five females. When Chelsea ovulates so too does Suzannah and the other females in the family. But Braveheart has only so much sperm and grooming time to go around and Katy, ranked seventh among her sisterhood, often misses out. Add to this Braveheart’s recent lack of attentiveness and, if I wasn’t a scientist full of anthropomorphic paranoia, I could probably hear those gelada divorce papers shuffling in the background.
Now you may be wondering where Braveheart’s dissatisfied females can turn to find ‘more of a man’. Afterall, with family sex ratios averaging four or five females per male there must be some eligible bachelors out there somewhere. Enter the other type of unit in the gelada social system: the All Male Group. This is where the action really hots up.
These tightly knit all-male gangs average around nine bachelors each, but range in size from two to 30. The individuals within each all-male group also cover a wide range of ages and there is typically one dominant male. Within my study population, Ivan is a sub-adult 6 year old and the leader of an 11 strong all-male group named ‘The Sharks’. The Sharks are unrelated but socially cohesive, spending 24 hours a day together and displaying group defence and grooming alliances as strong as any family. They patrol the edges of the herd in the manner of their namesake, and have a clear view of the number of females and domestic turmoil surrounding each family male. The only thing more impressive than an adult male gelada is a dirty dozen of these brat-packers swaggering toward you. Although they have no access to females - yet - they are always on the look out for an opportunity to dethrone a family male and succeed him. While only the top-ranked bachelor is likely to make the upgrade to family male, they are united in their common goal as it enables each bachelor to move up a rung in the all male group heirachy.
An 11 to one ratio might seem overwhelming but no amount of swagger or group strength by the bachelors can force a take-over while the final decision remains with the females. How they make this decision isn’t clear but they are provided with information about the male’s physical prowess, and presumably genetic strength, when family males engage in ritualised aggressive encounters with the bachelors. These displays rarely escalate into violence but provide a structured stage for males to spar and show off. Something like a gelada sports arena for the whole herd to watch. Typically, a family male will walk from his family in the large herd, strut up to the peripheral bachelor group and provoke them into chasing him, on mass. The chase is a somewhat leisurely and stylised jog, always accompanied by dramatic yelps and often incorporating lavish jumps over creeks, dust and rocks being kicked up and branches being broken. As soon as one family male has strutted his stuff he will return to his (hopefully impressed) females and be replaced by another family male who will engage the bachelors in a similar chase. Females may demonstrate their support for their family male by screeching vocally at the bachelors, or by grooming him upon his return from the sportsfield.
The bachelors also provoke the family males by shadowing family units that show potential for take-over or fission. This is where Braveheart is proving an interesting case among my study animals. For the last few months both the bachelors and I have been monitoring Ivan’s fall from grace. His inattentiveness to grooming his females, negligence of the infants and lax support for family defence are all high crimes in the gelada court and domestic unrest is hidden from no-one.
‘The Sharks’ have targeted Braveheart’s family and his females have demonstrated their interest in the eligible talent on offer by not moving off. With little support from his females Braveheart is provoked into chases that, over a period of days, become less ritualised and more ferocious. Screaming and with their lips peeled back, Braveheart and Ivan clash jaws and lock canines. Ivan is aided by his gang and eventually their long struggle pays off when Chelsea and her sisters move towards him and present their rear. They have chosen. Ivan has acquired a harem of females and will now begin his domestic and reproductive careers.
Like all deposed gelada males, Braveheart can do nothing about the take-over. His acceptance is evident in his submissive and reconciliatory gestures towards Ivan. But unlike most species in which single males gain and lose harems of females, gelada are probably unique in that Braveheart will stay with the family as a ‘follower’. In this role he will never again be allowed sexual privileges, but will help Ivan and Chelsea defend the family. In return, Braveheart will be maximising his reproductive output by staying with the unit and protecting his offspring.
For now, things appear peaceful in family unit J4, as they tumble over the edge of the escarpment to their sleeping cliffs below. But Ivan will have little time to relax into his new role as Family male. For the gang of bachelors who groomed and supported him during his ascendancy are now the enemy, and ‘the Sharks’ have new prey in their sights.
