Khalid stopped the pick-up truck and inspected the ground ahead in the light of the headlamps. There were a few tiny greyish plants on a gently convex plateau of jagged loose rocks. It felt like we had landed on a small and rather inhospitable planet. There was no track, and hadn't been for the past few miles – not since we had stopped to look at a wolf track in the dust.
"This is it," he said, "our campsite." He grinned. "It's not as bad as it looks: there'll be enough firewood to boil a kettle, and in the morning – you'll see – it's a good view."
The rest of the team were coming up in two cars. "And leopards?" I asked, "Are they here?"
Khalid made a face. "Insha'Allah [God willing]. There's a trail camera near here which we'll check tomorrow." He jumped out of the car and started unloading, a man used to this life of remote camps in the Dhofar mountains of Oman.
As a wildlife protection officer with Oman's Arabian leopard project, Khalid is on the front line when it comes to saving one of the world's rarest creatures. There are probably fewer than 200 individual Arabian leopards left in the wild, mostly in Oman, Yemen and Saudi Arabia. A few others, probably not viable populations, cling to life in Israel, Jordan and the UAE.
Oman has the only programme to conserve the wild leopards – an estimated 50 animals live in the mountains lining the country's Indian Ocean coast close to Yemen, around half of them in a protected area.
This is wild country, a place where the British army fought a forgotten war against communism in the 1970s, a place once famous for its production of frankincense. Its people are the Jebali, hardy, semi-nomadic camel-herders whose mother tongue is not Arabic but an ancient South Arabian language related to that once spoken by the Queen of Sheba. Khalid is from that community: a former shepherd, he once hated the leopard but is now converted, with total conviction, to preserving this astonishing creature
Around the campfire, we sip sweet tea and eat biscuits under a vast vault of stars. We have come here with a group of Yemenis, all eager to learn how the Omanis created Arabia's only genuine wildlife reserve. If the leopard is to survive, Yemen is the key, because it has plenty of the type of environment the animal needs. Sadly it lacks the resources, the knowledge and the organisational skills required. The only efforts are coming from the Foundation for the Protection of the Arabian Leopard in Yemen which gallantly soldiers on without much support from the outside world. No surprise in that of course, since Yemen is normally only mentioned in the media in conjunction with tales of politics or terrorism.
Visitors from other countries do come to Oman though. Conservation volunteer organisation Biosphere Expeditions arranges short volunteer placements to work with Khalid, and he's adamant that the foreign presence is important. "They do useful work helping us survey the mountains for leopards," he says. "And it makes a good impression for conservation with the Jebali community. We try to buy supplies from the locals, too."
Next day we trek down a steep mountainside, so steep that one team member gets vertigo and has to be helped back to camp. In gulches and canyons there are some hardy plants, including the frankincense tree, a species that made this area economically important centuries ago. The only sign of human presence, however, is some cartridge shells from the Oman-Yemen war of the 1970s.
Down in the wadi, we follow its bed until it stops at a vertical edge – now dry but obviously scoured by water in the rainy season. There are rock hyrax droppings everywhere – a vital sign as leopards love to eat these small mammals. We don't see any animals though, until we locate the trail camera that Khalid left here a month before.
We cluster around, eager to see the digital images as Khalid flicks through them: the rear end of an oryx, the hunched figure of a striped hyena, then lots of blurred shots of hyrax scuttling past. There are no leopards, but I'm getting the idea now: this is a ghost safari, a trip where the only means of putting together the landscape and its inhabitants is the motion-triggered remote camera. This understanding is like a light bulb coming on. Suddenly all those shy, non-tourist-friendly creatures of the world can be part of the international business of tourism and conservation – and that could be vital for their survival.
And it is a gorgeous colourful world that we view later on a laptop back at the camp. Dusty rocks burst into life with wolves, hyenas, antelopes and more. No leopards, however, and as I wriggle into my sleeping bag under the stars, I allow myself a small pang of anxiety: what if we don't catch a leopard image? It's vital for the film I am making there with Al-Jazeera.
I'm drifting off to sleep, noting the cold wind that has kicked up, when I hear shouts from Nasser, one of the Yemeni trainees. I am up in an instant, running across to cameraman Tom, jabbing him awake. I click on my headtorch and run across the rocks towards Nasser. He's pointing down the hill, his face glowing with excitement, and even fear. "Leopard! Leopard!"
Shining my torch where he is pointing, I catch a glimpse of two silvery eyes, not 50m away. They come on like a pair of headlamps, then are extinguished as the animal turns and runs. I go after it, but my torch is at the limit of its range and, frustratingly, I can't see the animal, only those twin orbs of light. There is one instant, a fraction of a second, when it is framed against the far side of the wadi and I get a sense of its size – certainly bigger than a fox, but maybe only as big as a hyena. Then it's gone.
Behind me, Nasser is deliriously excited. He's a Yemeni farmer from a remote mountain area, Jabal Milhan, and he knows a leopard when he sees one. The animal, he tells us, was standing less than 10m away from him. He has tracked the animals since he was a child, but then it's about that long since the last sighting in Milhan.
Khalid is diplomatic. "In all my years tracking leopards, I've never seen one." He holds out the prospect of proof, however. We can clamber down to another trail camera below where the animal appeared. There may be some visual support for Nasser's claim
As the sun rises, we are all already up. It's bitterly cold and we are scrabbling around for shards of thorny firewood to boil a kettle. But by 8am, when we get going, it's already hot.
It takes several hours to get down to the hidden camera, on a cliff ledge. All along the sandy edge we find leopard tracks, very clearly heading up towards the camp. And at the camera we are rewarded with some marvellous shots of a male leopard. Nasser is particularly gleeful, feeling vindicated.
That night, camping closer to the sea, I chat to Salah al-Mahthori, from the Omani government's Arabian Oryx project. He gives a sobering account of conservation efforts. The wild oryx population had been hunted to extinction by 1972, when the conservation effort began. It met with initial success: numbers grew from 40 to over 400. But with success came publicity, and with that poachers. Now the Omanis are once again fighting to rescue the oryx from the brink of extinction. Conservation, he reminds me, is a battle that goes on indefinitely.
Silhouetted against the night sky we spot a distant fox, running away from our voices. It is the only wild animal we see with any clarity in an entire week of camping in the mountains and that fox's wariness of humans seems very well justified indeed.