Chainsaw the best tool to save Africa's rhinos?

JOHANNESBURG -- Desperate times call for desperate measures, and with rhino numbers plummeting, the situation is so desperate that conservationists are cutting off the animals' horns in a bid to ensure their survival.

CBS News correspondent Debora Patta watched as a rhino -- one of dozens at the Phinda Game Reserve in South Africa -- was sedated so its horn could be removed. All the others in the park are to undergo the same procedure. Head Ranger Simon Naylor knows his rhino are marked animals; their horns a deadly bounty on their heads.

He's made an uneasy peace with the difficult decision to dehorn the rhino population, which some critics say may harm the animals' ability to live successfully in the wild.

"I think in the last few years we've reached that tipping point in Africa, and certainly in South Africa. There are more deaths now than births," Naylor told CBS News. "And so it's a species heading towards extinction if we don't do something drastic."

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Naylor directs veterinarian Mike Toft on which rhino to dart with a potent tranquiliser.

Toft must ensure the precise dosage when he fires the dart from a hovering helicopter -- too much could be lethal.

Once the drug kicks in, the rhino is quickly blindfolded and a chainsaw tears through the massive horns. It is hard to watch and listen to, but the rhino does not feel any pain.

Although the process is briefly traumatic, Toft says it's a bit like filing a human nail.

"I'd rather see this little guy upright in two years time than in a ditch upside down and bloated dead from having had his horn poached, so for me it's a no brainer," he said.

Rhino horn is what this war is being fought over; it is still so valuable to poachers that it's immediately whisked off the property to a secret location, out of the reach of criminal syndicates.

The appetite for rhino horn powder is so high that organised crime rings can net about $150,000 for an average horn.

The trade is driven primarily by Vietnam, where it is sold under the delusional belief it cures cancer, enhances virility and prevents hangovers. For this, at least three rhino are killed every day in South Africa.

Toft is on the front line. He has performed more than 200 post-mortems on slaughtered rhino. He says dehorning is a no-brainer.

The dehorned rhinos are sprayed with a purple disinfectant -- the mark of survival -- and then injected with an antidote to counteract the grogginess. There is no permanent damage to the animals' health.

Once back on its feet, the rhino pants, calling out to find its friends and family.

It will become increasingly rare to see a rhino with its horn still attached on this reserve, but Naylor's team believes that is a price worth paying to save the species.

The good news is that the rhino horn will grow back, and the reserve is hoping the dehorning is simply an interim measure that will significantly reduce the threat of poaching.