Dehorning Dilemma

What characterizes a rhino? Some might say its huge size, immense power, thick legs, or prehistoric appearance. But, for most, surely it is their horn. In recent years dehorning has become more commonplace as the threat from poaching continues to rise. Dehorning doesn’t hurt the animal – it’s like cutting fingernails or trimming horses’ hooves. But, as with any surgical procedure, it is not without its risks, and – as with any proposed solution to a very complex problem – dehorning will never be a panacea for poaching.

close-up photo of a dehorned rhinocerosphoto by Ann and Steve ToonDehorned white rhinos on a rhino farm in South Africa

Evidence shows that dehorning has a place as part of a suite of measures to protect rhinos from poachers but, when conducted in isolation, can have unintended consequences.

On first look, dehorning seems like an obvious solution, and some evidence backs up this claim. In the 1980s and ‘90s, Namibia trail-blazed dehorning and none of its dehorned rhinos were poached. Rhinos dehorned in recent years in certain Zimbabwe Lowveld conservancies appear to have a 29 percent higher chance of surviving than their horned counterparts. In Mpumalanga, South Africa, just over one-third of all the reserves’ rhinos (excluding Kruger National Park) have been dehorned, and out of the 33 rhinos killed from 2009-11, only one was a dehorned rhino.

However, there are numerous cases where dehorning hasn’t saved rhinos. For example, in the early 1990s in Hwange National Park in Zimbabwe, most of the dehorned rhinos were killed just 12 to 18 months after being dehorned. In Zimbabwe’s Save Valley Conservancy, six newly dehorned rhinos were poached between January and August 2011 (one was killed within 24 hours and another within five days of being dehorned).

Why do poachers continue to target hornless rhinos? During any dehorning exercise a stub of horn will remain because the bottom four inches or so have a live core. Removing this would be extremely painful and might even kill the rhino. So even a freshly dehorned rhino still has a significant stub that can be sold for a high value. Poachers may also kill dehorned rhinos out of vengeance. In Hwange, it was thought that poachers killed dehorned rhinos to avoid tracking them again. If there is thick bush or hilly terrain poachers may not see if the rhino has an intact horn prior to shooting.

As with any invasive procedure involving the use of anaesthetic, there is a risk to the animal during the operation – including death. Dehorning is also incredibly costly due to the equipment and expertise required, and the effort of tracking and darting the animals, with estimates of up to $1,000 per operation. By one estimate, a one-off dehorning of all the rhinos in Kruger would cost around US $5.8 to 8.8 million. To be effective, dehorning needs to be done every 12 to 24 months as horns grow back. Furthermore, despite some claims to the contrary, 100 percent of a wild population could never be dehorned. The operation is too risky for a pregnant female, and some animals will hide away successfully in the bush.

A key question, of course, is whether rhinos need their horns. The evolutionary purpose of rhino horns isn’t entirely clear, but horns appear to have several behavioral functions, including influence on mating choices, predator defence, foraging, digging for water, and territorial dominance. Given the cost and risk of the procedure, dehorning should be a last resort under severe and sustained poaching threats.

A first-line defence for conservationists should always be anti-poaching monitoring and security. Dehorning has its place – but only as part of a suite of tactics.

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