The sun is still a smear on the horizon as I hurry to beat the dawn, slaloming through an army of giant lobelia, over grassy tussocks still spongy from last night’s rain. I awoke feeling groggy—out in the open, at 15,000 feet, sleep comes fitfully—but the weariness is soon replaced by keen expectation. The creature I’m pursuing is most active in the morning and my reward comes quickly: a chorus of chirrups drifting down the tableland from the north.
They call this place the Roof of Africa. I’m in the Simien Mountains of Ethiopia, a World Heritage site. The earth beneath my feet began its journey skyward 70m years ago, when lava bubbled up from volcanic fissures in the Horn of Africa. Over time the lava solidified, layer on layer, until it had formed a giant hemisphere of basalt, three miles thick. When the flow slid to a halt, glaciers gnawed at its edges to form cliffs and rain seeping into cracks carved yawning canyons. Elevated and isolated, the creatures here evolved to fit their surroundings.
In a charismatic cast of animals—scimitar-horned walia ibex, flame-furred simian wolves—the character now appearing in a shadow play of frolicking silhouettes on a nearby ridge is king. The gelada, Theropithecus gelada, is a most atypical monkey. Descendant of a primate that once patrolled grasslands from South Africa and Spain, it is now confined to the soaring crags of northern Ethiopia. As I watch the gelada up here, it is difficult to imagine them anywhere else.
The crowd gathering—first five, then a dozen, now 20 or so figures, framed against the early haze—has spent the night on the cliff-face ledges of escarpments reaching up to a mile high. At the break of day, they clambered onto the plateau to feed and play. About two feet tall, with flowing tawny fur and a black, puckered jaw, the gelada is the only monkey to subsist almost entirely on grass. With the dexterity and concentration of a watchmaker, their nimble fingers can harvest 150 blades of grass every minute. As they spend so much of the day shuffling around on their backsides, the sexual display organs that usually adorn a monkey’s nether regions have migrated to the chest. It’s this distinctive marking, an hourglass patch of crimson skin, that gives rise to the gelada’s common misnomer: the bleeding-heart baboon.
Their communal structure is complex. The basic social unit is the harem: a group of females and young, ruled by an alpha male with leonine fangs and a rock-star mane. Other bands consist of bachelor males, pretenders to the alpha males’ throne. The resulting intrigue—bachelor bands conspiring to unseat their dominant rivals—would befit the medieval courts of Ethiopia’s Solomonic emperors. More often, however, the gelada are a cohesive bunch. While harems commonly number a few dozen, by day they frequently converge to form much larger herds, up to 800 strong. Of all primates, only humans are more terrestrial and more political. Emboldened by the strength that comes with such numbers, the gelada tend to have fraught relations with the locals. The Ethiopian boy-herders carry slingshots to fend off raids by gelada special forces on their wheat fields.
Here they are protected, and seldom shy with humans. Yet it still comes as a surprise when this troop heads straight for me. Scampering across the frosty tundra, tails raised, a band of about 50 descends the steppe, preceded by the non-stop symphony of hums, chirrups and squeaks—a chatter of over 30 distinctive sounds—that binds the harems together. For 20 minutes they linger, so engrossed in the morning routine of grazing and grooming that I’m hardly worth a second glance. For the outsider, sitting among a gelada herd is one of the most wonderful animal encounters imaginable; few beasts provide the opportunity for such prolonged proximity—until, at some invisible signal, they rise as one, and move off towards the pink sunrise.