High above a dusty landscape dotted with thorn trees, Deon Cilliers maneuvers an ultralight aircraft, searching for the radio signals of two young male wild cheetahs. Earlier this morning, the duo killed and then devoured an ostrich, so now they are probably resting in some shady spot below.
As we pass over one cluster of trees, the rhythmic tick-tock grows louder, indicating that the cheetahs must be nearby. But then, just as suddenly, the signal fades. We have flown right overhead without catching so much as a glimpse of the elusive predators.
During the next 10 minutes spent circling over the same swath of land, watching futilely for signs of feline life, one thing becomes apparent: Cheetahs are good at hiding. So good, in fact, that even after years of study, researchers still know little about the lives of these shy, mysterious cats. That is all about to change, researchers hope.
For decades, these small, spotted predators with black tear marks under their eyes - the world's fastest land mammals - have been sliding toward extinction. Ultimately, their survival in the wild here may well depend on what Mr. Cilliers and his associate, Kelly Wilson of the nonprofit DeWildt Cheetah and Wildlife Trust, can learn over the next few years, as they conduct the first census in South Africa of free-roaming cheetahs.
This arid, scrubby region near the Botswana border is one of their few remaining habitats in South Africa. Once widespread across this continent and parts of Asia, the cheetah has gone extinct in at least 20 countries since 1900.
Here and across Southern Africa, isolated wild populations struggle for survival. They are hunted, shot by farmers, pushed off their rangelands by agriculture, plagued by inbreeding, and bullied by larger predators in conservation areas.
Once thought to number in excess of 100,000, the world's cheetah population now hovers somewhere between 12,000 and 15,000. Cilliers estimates that there are between 400 and 700 free-roaming cheetahs left in South Africa.
In this area around the nature reserve, however, it is not so much the scarcity of cheetahs that worries Cilliers. Rather, it is their troubled relationship with local farmers. At least 100 cheetahs have been illegally shot over the past two years. And in other areas of the country, Cilliers says he has come across cases of cheetahs being poisoned, run over with trucks, and scorched with fire by angry farmers.
Across the lands where wild cheetahs range, farmers have recently poured huge sums of money into converting traditional cattle farms to wild game ranches. And many of the same animals roaming on these newly reclaimed wild lands also happen to be prime cheetah food: impala, blesbok, young sables, and rare antelope known as roans.
"Ten years ago, nobody knew what a cheetah looked like," says neighboring farmer Richard Heroldt. Now, "if you talk to any farmer, everyone's seen cheetah on their land."
It is a predicament similar to that of the wolf in the American West.
Cheetahs have moved to where their favorite foods are most abundant, and are vilified by farmers who often have invested upwards of $10,000 per antelope. To make matters worse, says Cilliers, farmers blame them for kills made by other predators.
Cheetahs are more visible than leopards and hyenas because they hunt in daylight. The lithe, delicate-boned cats stalk their prey, and then rely on short, powerful bursts of speeds up to 70 miles per hour to bring an animal down. Cheetahs must eat quickly before larger predators move in and steal their food, so they leave plenty of remains behind. For farmers, this waste adds insult to injury.
"That animal is worth a lot of money to you, and the cheetah is worth nothing," says Mr. Heroldt.
The attitudes of farmers are key to the survival of cheetahs in the wild.
Cilliers spends much of his time visiting farms and trying to persuade people like Heroldt that they actually can coexist with cheetahs on their land.
Instead of shooting cheetahs, he urges farmers to trap them. DeWildt then collects the animals, and pays the farmer about $1,500 for his trouble. DNA samples are taken, and the cheetah is fitted with a transponder and relocated to a private game reserve.
This payment scheme for farmers is controversial. Critics say it unduly rewards farmers, and puts a price on the life of a cheetah. Cilliers argues that compensating farmers has saved the lives of cheetahs.
At best it is a short-term solution. Farmers are clamoring for cheetah hunting to be made legal. Some of them demand more money from DeWildt for captured cheetahs, while others sell the cats on the black market instead. From there, they are smuggled into neighboring countries where cheetah hunting is legal, or sold to zoos as captive-bred animals, Cilliers says.
"Ultimately, we need to convince farmers to be more tolerant towards predators," he says. "They've been here for thousands of years, and they're not going to eradicate all the game. [Farmers] are going to lose a certain percentage, and must budget for that, just like a maize farmer loses some of his crop to pests."
That's where the cheetah census comes in. In a recent example of successful cooperation with farmers, the two young male cheetahs who now wear radio collars were captured on a neighboring farm, and turned over to Cilliers and Ms. Wilson to become the first unwitting participants in the cheetah census.
For the next two years, Cilliers and Wilson plan to keep tabs on where they travel, what they kill, and how often they eat. When Cilliers finally spots them basking in the sun, he says he finds it curious that they are not far at all from the spot where they were captured.
In addition to monitoring cheetah by air, Wilson, who is in charge of the census, follows a constellation of cheetah clues, from which she is trying to piece together a clearer understanding of all these unanswered questions.
She has set up cage traps, remote- triggered cameras at cheetah thoroughfares, and scent-marking posts throughout the reserve. She interviews farmers. She scans the dusty ground for tracks. She has learned to identify individual cheetahs in photographs by the distinctive spots on their coats.
"Once I get the photos and put them together, I'll be able to understand who's doing what," she explains, examining a pair of cheetah tracks that pass in front of one of the cameras.
But progress is painstaking, incremental, and often just as elusive as the cats themselves.
Wilson sees cheetah pawprints at the threshold of one cage trap. A goat waits in an adjacent cage. The area is ringed with a barrier made of thorny branches, constructed so that the cheetah is forced to walk into the trap in its attempt to get the bait.
But no luck this time. Judging from the tracks, it appears the cheetah paused, considering whether to go after the goat, and then sauntered off into the dense bush.