A record number of rhinos were poached this year in South Africa, home to the greatest number of the animals, as rising demand in Asia for their horns led to increased killings of the threatened species.
At least 443 rhinos have been killed in South Africa in 2011, up from 333 last year, according to National Geographic News Watch.
The street value of rhinoceros horns has soared to about $65,000 a kilogram (2.2 pounds), making it more expensive than gold, platinum and in many cases cocaine, as a belief — with no basis in science — has taken hold in recent years in parts of Asia that ingesting it can cure or prevent cancer.
South Africa, home to more than 20,000 rhinos, was losing about 15 animals a year a decade ago. But poaching increased dramatically from about 2007 as a growing affluent class in places such as Vietnam and Thailand began spending more on rhino horn for traditional medicine.
The number of rhinoceroses dying unnatural deaths in South Africa, either through illegal poaching or legal hunts, has reached a level likely to lead to population decline, according to a study by Richard Emslie, an expert in the field.
About half of poaching takes place in Kruger National Park, the country's flagship park covering an area about the size of Israel, where soldiers and surveillance aircraft have been deployed in recent months to slow the carnage.
The park has been the focal point of an arms race as gangs of poachers sponsored by international crime syndicates have used high-powered weaponry, night vision goggles and helicopters to hunt the animals, investigators said.
In a separate study, the number of large scale ivory seizures is likely set a record this year, pointing to increased African elephant poaching.
South Africa, home to over 90 percent of the rhinos in Africa, grants licenses for legal hunts, with a growing number of the horns then mounted as trophies, shipped to Asia and sold on the black market, according to police and customs officials.
Many poachers were trained by Mozambique's military or police and are now living in squalor in the border region next to Kruger, South African investigators said.
Their cut of the rhino money is relatively small compared to other players in the international trade but is considered a fortune at home.
Rhino horn has been used for centuries in Chinese medicine, where it was ground into a powder and often mixed with hot water to treat a variety of maladies including rheumatism, gout, high fever and even devil possession.
In recent years, it has also taken on a reputation for being an aphrodisiac and cancer cure.
"Nothing is more tragic than to see this totally unnecessary and brutal killing of an animal for its horn, and the horn in turn has zero medicinal value," said Pelham Jones, a leader of the South Africa Private Rhino Owners Association.
Campaigners in South Africa are urging President Jacob Zuma to uphold a 1993 treaty on international trade in endangered species and to engage with China, Vietnam and Thailand with a view to ending the trade in rhino horn and other animal parts.
In September the country's Department of Water and Environmental Affairs signed a memorandum of understanding with Vietnam which it hoped would lead to an agreement to help curb rhino poaching in South Africa. The department is seeking similar agreements with Thailand and China.