South African and Kenya are seeing a dramatic increase in the killing of rhinos for their horns, according to national park officials.
Last year, 333 rhinos were killed in South Africa, including 10 critically endangered black rhino species.
That's the highest on record, and nearly triple the year before.
In the first two weeks of 2011, six more rhinos were lost to poaching, the international wildlife monitoring group TRAFFIC said in a statement.
"The recent killing increase is largely due to heightened demand for rhino horn, which has long been prized as an ingredient in traditional Asian medicine," TRAFFIC stated. "It has been claimed recently that rhino horn possesses cancer-curing properties, despite there being no medical evidence to support the assertion."
Kruger National Park, home to South Africa's largest population of rhinos, was hardest hit, losing 146 rhinos to poaching.
South Africa is home to some 21,000 rhinos, more than any other country.
"The current wave of poaching is being committed by sophisticated criminal networks using helicopters, night-vision equipment, veterinary tranquilizers and silencers to kill rhinos at night while attempting to avoid law enforcement patrols," TRAFFIC stated.
"This is not typical poaching," said Joseph Okori, who runs the African rhino program at the conservation group WWF.
In Kenya, officials earlier this month recovered elephant tusks and rhino horns in the northern part of the country.
"At least 20 rhinos were killed across the country since early last year," said senior warden Aggrey Maumo, who was involved in the operation.
Kenya's wildlife, which draws tourists from around the world, has suffered from poaching, severe drought and floods in recent years.
