Poachers have butchered the last adult rhinoceros at a South African game reserve, cutting off her horn and letting her bleed to death, the chief game ranger says.

“We’ve had rhinos here for 20 years,” Japie Mostert told the Star on Thursday from the Krugersdorp Game Reserve, 60 kilometres northwest of Johannesburg. “She was the last one.”

The nine-year-old rhino at the 1,400-hectare reserve was likely attacked by poachers who hovered in a helicopter, shot her with a tranquillizer dart then leapt out and sliced her horn off with a chainsaw, Mostert said.

“The whole operation would take seven to 10 minutes.”

The animal’s female calf had been killed by poachers in January; her nine-month-old male calf was taken to a different reserve for sanctuary after the killing on July 14, he said.

It would take “a guard working day and night” to protect the rhinoceroses, which are being slaughtered at a record rate across South Africa, he said.

Rhino horn has been used for centuries in Traditional Chinese Medicine, although tests reported by National Geographic have shown that it has no special properties and is similar to a fingernail.

More than 90 rhinos have been killed in South Africa this year, compared with 122 in all of 2009, said David Mabunda, chief executive officer for the South Africa National Parks. Only 13 rhinos were poached in 2007.

Ninety per cent of the world’s rhinos have been slaughtered in the last 40 years to feed the illegal horn trade in China and Vietnam.

Poachers can get more per ounce for rhino horns than for gold.