The cry reverberates around the valley, ringing loud and shrill like an army of ghouls. I lift my head from the coat I've rolled up as a pillow, the moist fug of the tent clinging to my cheeks as I pause and listen. "Ooweh," it comes again, and I scramble out of my sleeping bag to unzip the canvas and peer carefully outside. In the near distance, shining through the inky darkness, I spot five fires dotted around our camp, burning bright under a fierce canopy of stars. The horsemen are awake; I can see their shadowy figures in the moonlight, furiously stoking the flames and surveying the cliffs around us. Hyenas, I realise. They're surrounding the camp to try to get to the horses. There goes my night's sleep.
I'm high up in Ethiopia's remote Bale Mountains National Park. Four thousand metres high to be exact. The air is pinched, the terrain demanding - a rugged, undulating expanse of mountains, rivers and wind-battered plateaus. I'm not a "seasoned" hiker, but I am fairly fit. Yet this trek has already proved a challenge; the altitude clutching at my temples with a Vulcan grip, filling my legs with lead and sucking the thin air from my lungs.
Sitting in southeast Ethiopia, 400km from the capital Addis Ababa, the park is part of the country's dramatic highlands - playing home to Tullu Demtu, the second-highest mountain in Ethiopia and the highest plateau on the African continent (earning it the nickname "the rooftop of Africa"). Rarely visited by tourists, only a small number of operators run trips out here. The mountains are also home to some of Ethiopia's rarest and most fascinating wildlife - packs of roaming wild dogs, elegant mountain nyala and the Ethiopian wolf, Africa's rarest carnivore, a tantalising three times rarer than China's elusive giant panda.
We've been spending daylight hours trekking, gliding through fields bursting with silvery heather and forests of Triffid-like Giant Lobelia; across windswept plains dusted with amethyst wildflowers and towards volcanic mountain ranges rising in the distance like huge serrated teeth. In the hot sun of the day, our impeccable mountain guide, Ayuba, points out caves dating back almost 40 million years, and cliffs whose crags are known homes to preying leopards. We dip our fingers in waterfalls and weave in and out of vast herds of goats. At night we set up camp at the bottom of cliffs while troupes of baboons look on bemused, or bed down for the night alongside glistening streams where bearded vultures soar, dropping the bones of their prey from great heights so that marrow oozes out of the cracks like liquid gold.
The morning after the night of the hyenas we're up at dawn to a breakfast of scrambled eggs and chapati, cooked by camp chef Ebrahim (the horses, thankfully, are all still present and correct). I pull on my hiking boots, leggings, down jacket and cap and we, the great unwashed, begin our climb up to the blustery Sodota plateau. As we amble along, flocks of ibis skim past with an unholy cackle, rare blue-winged geese (the most isolated on the planet) plod by, and rock hyrax (small, chinchilla-like creatures that are actually a direct relative of the elephant) emerge from bluffs to screech furiously at us. There may be few humans here but there is certainly plenty of wildlife.
When we reach it, the plateau is a stark place. Pockmarked with alpine shrubs. Battered by sharp winds. Bleak. As we walk, giant mole rats the colour of ginger biscuits poke their heads up out of their holes and the screech of hunting augur buzzards fills the air. I scan the land: this is wolf country and, with fewer than 500 of the creatures remaining in the wild, I'm determined to spot one. All seems quiet until, in the distance, suddenly, it appears: a russet-coloured creature, kind of like a jackal, kind of like a fox - with white-socked legs and a distinctive black-tipped tail - skipping across the open plain with staccato footsteps. Just minutes later, we spot another, resting on its haunches, its elegant snout sniffing at the air. That evening, as we start our nightly ritual of tent constructing, fire-building and pulling on as many layers as possible to fend off the biting cold, we spot another two wolves - ambling nimbly past the camp as the sun sets, shafts of amber light warming their fur.
The next morning, we wake to tents slicked with dew, and commence a gruelling high-altitude hike to the Raffu campsite, flanked by cooks, porters and horses laden with bags - clanking as they pass me with great ease. I have to stop every couple of minutes to catch my breath; the air here is so thin even Ayuba our seasoned guide succumbs to a nosebleed. My knees are starting to throb, my feet are blistered and burning, a dull ache spreads across my hips like a rot. But the reward is worth it. After a slog of a climb we reach the stone forest - a fantastical-looking place filled with otherworldly rock formations, absurdly vivid forests of lobelia and leopards, just the feel of them, snaking around boulders and scenting the air.
Our last day comes with a smidgeon of relief. My bones are weary. My lips are blistered, my hair matted, a thick black line of dirt sits in my fingernails like soot. But we finish on a wide plateau, hiking together with the horses, cooks, guides and horsemen who have made our journey so much easier than it should have been. Surrounded by cows, sheep and local nomadic shepherds who wave as we pass, we close in on our final destination: a small speck of a minibus on the road in the distance. When the finish line arrives, I feel a sense of elation. I'm not far from the top of the world, I guess, and there is no one else in sight other than our small group of makeshift adventurers. It's pretty special, I concede, this small, wind-beaten pocket of wilderness.
YellowWood Adventures offer fully guided nine-day trips from £1299