Wildlife prices are tumbling in South Africa as game breeders are squeezed by restrictions imposed on trophy hunting after Cecil the lion was killed, and the worst drought on record has forced farmers to sell animals.

The average price of a buffalo bull fell 71 per cent to 95,704 rand ($7300) in 2016 and is now a fraction of the record 2.1 million rand set in 2013, auction house Vleissentraal said.

Prices of golden wildebeest, black impala and kudu bulls have dropped by 60 to 80 per cent.

"There has been an onslaught on the trophy hunting industry and that has fed through to prices," Peet van der Merwe, a professor of wildlife and tourism at South Africa's North West University, said.

"The drought has also hurt farmers, many of whom had to sell stock."

The collapse marks the end of four years of skyrocketing values for South African wildlife, which are often specially bred for bigger horns or coloued coats. The practice has been criticised by environmentalists and even some hunters for what they see as unnaturally tampering with the gene pool.

The boom in prices from 2011 to 2014 was driven by growth in trophy hunting and investment from high-net-worth individuals, including luxury-goods billionaire Johann Rupert and South African Deputy President Cyril Ramaphosa. Some farmers also switched from cattle to game.

That all changed in 2015. The country experienced its worst drought since records began in 1904, making feed more expensive, while US dentist Walter Palmer provoked worldwide outrage by hunting Cecil, a 13-year-old lion known for his striking black mane, in Zimbabwe.

After the death of Cecil, who was part of an Oxford University research project, the US, France, the Netherlands and Australia tightened restrictions on importing animal carcasses, while United Airlines and Delta Air Lines banned customers from transporting hunting trophies.

Prices of specially-bred colour variants also fell last year. The average golden wildebeest bull sold for 395,363 rand, a drop of 61 per cent from 2015, Vleissentraal said.

Black impala rams plunged 78 per cent, and even lower-value so-called plains game such as kudu tumbled 64 per cent. Wildebeest are usually dark grey and impalas are more commonly reddish brown.

Prices are also being affected by expanded supply of farmed wildlife. Seeing the high prices, many cattle farmers converted to game in 2012 to 2014, temporarily pushing up demand for breeding stock before some were forced to sell during the drought, van der Merwe said.

Still, the value of the costliest buffalo increased in 2016. South African businessman Peter Bellingham paid 44 million rand for a 25 per cent share in Horizon, Africa's biggest-horned, tuberculosis-free buffalo last February. That values Horizon at a record 176 million rand, surpassing the 40 million rand paid for a buffalo named Mystery by a group including Rupert in 2013.

Horizon's horns are 140 centimetres wide, compared with Mystery's 134 centimetres. Breeders in South Africa, the biggest market for the animals, are willing to pay record prices for the genes of buffaloes that could increase their herd's horn span, which is desirable to hunters.

Africa Hunt Lodge, a US-based tour operator, advertises "hunt packages" to international clients travelling to South Africa that include killing a lion for $US30,000.

For the money, hunting tourists typically get a seven- to 10-night stay in a luxury lodge, gourmet food with an emphasis on meat dishes, and hunting permits.

Bloomberg