South African Air Force fighter pilots, and many a civilian aviator, too, would have been saddened by the recent death of Mpho, the cheetah. They would also have been grateful to the fleet-footed predator for nearly a decade of service patrolling a remote air base, chasing warthogs and other small game off the runways in one of the wilder parts of South Africa.
Mpho, meaning "gift" in the indigenous seSotho language, was stationed at Hoedspruit Air Base in the northeast of South Africa, near the Kruger National Park, a region still teeming with wild animals even outside the park's fences.
In the days of apartheid and southern Africa's anti-colonial wars Hoedspruit served as an advance air base at which Mirage jet fighters were stationed. After South Africa's political settlement in the early nineties, it started doubling as a civilian airport called Eastgate, resulting in passenger jets calling.
From the outset, warthogs were a frequent menace on the runways. But smaller antelope like impala were also a hazard to the aircraft. Animals wandering onto the runway while aircraft were landing or taking off could easily cause a disaster.
The air base is on a 4,900-acre (2,000-hectare) piece of land which, apart from landing strips and small buildings, remains wild bush country. It also has substantial numbers of game inside its fence. And making the problem worse is the preference of grazers like warthogs and impala for the short, mowed grass next to the runways, from where they can all too easily dart into the path of speeding aircraft.
Major Philip Oosthuizen, head of the base's environmental services, says the airport administration first tried to shoot the game. But this made the problem worse: "It proved impossible to exterminate them. The warthog simply hid in holes and the antelope in the bush where they kept breeding, and more kept coming into the base area through holes the warthog dug under the periphery fence.
"Rather than driving them off, the shooting succeeded only in scattering them and leaving those remaining skittish and even less manageable.
"When left alone, the warthog move about in groups and the impala in herds. This makes them easy to spot and to be driven away from the danger areas. With the hunting, they scattered and started dashing singly over the runways. It just made it all so much more dangerous," says Oosthuizen.
It was then that he came up with the idea of resorting to nature's way, by introducing cheetahs to keep the small-game numbers down without scattering the groupings in which they move about.
Capable of reaching speeds of 60 to 70 miles per hour (97 to 113 kilometers per hour), the cheetah (Acinonyx jubatus) is the fastest of the land mammals. The big cat typically preys on smaller antelope, warthogs, hares, and game birds-the very animals that range freely on the Hoedspruit property.
Oosthuizen first introduced a pair of female cheetahs to the air base-but this presented an unexpected new hazard.
Unlike the males, which move about in bachelor groups of two or three and who like to hunt together, female cheetahs move about and hunt singly. The trouble is that they are then unable to eat their whole catch by themselves, and the remains entice vultures, which are an even bigger threat to aircraft.
In 1994, they were replaced with two males: Mpho and Mphonyane, the latter meaning "small gift."
It was decided not to have females join them, says Oosthuizen, because this could set them fighting. And their purpose was not to breed but to keep the warthogs and impala in check.
Mphonyane drowned some years later when he fell into an air-base swimming pool, possibly while chasing after a warthog. He was replaced with a new young cheetah male called Kleintjie (the Afrikaans word for "small one").
Mpho went on to reach the ripe old age of 14 years, considered extraordinary for a cheetah. He was about to be retired earlier this year to the cheetah breeding facility at the nearby Kapama private game reserve to spend his last days in protective comfort when he went missing.
Air Force personnel were concerned. They had a few days earlier noticed that he had separated from his younger hunting partner. They also once saw him driven off his warthog kill by baboons, a sure sign that he was weakening.
His radio collar was out of order, and by the time he was found he was so weak that local veterinarian Peter Rogers considered it better to put him down. He had baboon-bite marks, but the main cause of his weak condition proved to be kidney failure.
Rogers says cheetahs' high-protein diet tend eventually to cause this, though in the wilds they normally do not live long enough for it to become a problem. From about eight years they start weakening and often starve, or get killed by bigger predators, like lion.
Meanwhile the job of keeping the runways safe has to carry on. It means the remaining cheetah, Kleintjie, has to be joined by some new colleagues to do the job.
In early August, two young males were brought from a breeding station and placed in an enclosure next to another in which Kleintjie has been put. Major Oosthuizen says the idea is to allow a bonding process to develop before putting them together, and then setting them free to start their air-base patrol. 
