Caught in the crosshairs

Dehorning is a controversial method used to stop rhino poachers in Africa – but does it really work?

December 19, 2013

There are two ways to remove a rhinoceros’ horn. One is the way poachers do it – by shooting the rhino dead and hacking off its horn at the base. Then, there’s the way conservationists do it, a far more humane but complicated procedure. First, they catch and sedate the rhino. Next, they use a marker to draw a line a few centimeters above the base of the horn – just high enough to miss the delicate blood vessels in the rhino’s snout.  Then, they saw off each horn at the line. Finally, they smooth the stumps and rub tar over them to keep them from drying out and cracking.

It may seem crazy to deliberately deprive the rhino of its most iconic feature, which the animal uses to spar with rivals, attract mates and defend its young from predators. But to many experts, this drastic action is crucial to deterring poachers, who kill the animals and sell their valuable horns for use in traditional medicines and crafts in places like China and Yemen.  “Dehorning” has been adopted as an anti-poaching strategy in several African countries over the past few decades, but its efficacy is hotly debated.

Critics of dehorning have questioned whether it might affect the rhino’s behavior and reproductive success, whether it really reduces poaching and whether the time and money it requires make the practice sustainable. The stakes in the debate are high: The western black rhino – a subspecies of black rhino – was declared extinct within the past two years, and remaining rhino populations are growing sparse.  Emotions regarding rhino welfare have never run higher.

“It’s a long, thorny, pot-holed, emotive road to dehorning,” said Joel Berger, rhino researcher and chair of wildlife conservation at the University of Montana. Rhino poaching has been a serious problem for decades.  Historically, African governments have implemented a variety of anti-poaching techniques, including hiring armed guards and fencing off rhino populations, but these have not been enough to stop poachers. As an alternative, dehorning was first introduced in Namibia in the 1980s, and is now practiced in several other countries, including Zimbabwe and South Africa.  Disagreements regarding the consequences of dehorning have experts treading lightly, however.

“Highly controversial research in Namibia suggested adverse effects [on rhinos],” said Raoul du Toit, director of the Lowveld Rhino Trust in Zimbabwe. Berger and his wife, Carol Cunningham, conducted the research in question in Namibia in the early 1990s. In 1994, they published an article in Science suggesting that dehorned mother rhinos were less capable of defending their babies against predators than horned rhinos. Their results were unpopular with the Namibian government, which afterward declined to renew the couple’s authorization to conduct rhino research in the country.

Du Toit claimed the dehorning controversy stems from Berger’s work, but Berger insisted he had no opinion on dehorning at the time the study was published. “I let the data fall where they were and let other people decide how they wanted to proceed,” he said. “I know that when we started our work we didn’t have an opinion one way or the other.”

Twenty years later, Berger has more defined views. “My opinion is that whatever it takes to save rhinos legally is what should happen,” he said.  For many researchers, this means continuing the dehorning programs. Du Toit, for one, insisted humans are a greater threat to rhinos than any alleged side effects of dehorning.

“Dehorning is not a significant issue for rhinos in terms of behavior and reproductive health,” Du Toit said. “The evolutionary advantages of possessing a horn were developed before AK-47s were invented and are not such advantages now.” Research published in 2013 by Du Toit and Natasha Anderson, rhino coordinator for the Lowveld Rhino Trust, challenged some of the supposed consequences of dehorning.

Their data suggest that the calf mortality rate in a population of dehorned rhinos was no higher than normal, a contradiction of Berger’s study. A sample population of 23 dehorned females exhibited normal intercalving intervals – the amount of time females wait between birthing calves – and overall population growth rates have remained stable, suggesting that dehorning does not negatively affect population sizes. The paper also examined herds to see if dehorned males were more easily ousted from their home territories by horned males. The study, based on a sample of 30 dehorned male rhinos, suggested this was not the case.

“All these kinds of ecological impacts are kind of theoretical,” said Andrew Taylor, coauthor of a 2011 Endangered Wildlife Trust report on rhino dehorning. “In places where they’ve done dehorning, there are often other factors that get involved and make it difficult to tease apart exactly what’s happening.” Some areas have higher herd densities, making fights between males more likely, Taylor said. Other areas have more predators than others, putting calves in greater danger. “One of the key points about this whole issue is that there are no absolutes,” Taylor added.

One of the more variable issues is funding.  The high price-tag on dehorning – Taylor’s report estimates it can cost anywhere from $620 to $1,000 per rhino – means the practice is often too expensive to be considered practical for large herds. Taylor said dehorning in South Africa is often limited to small, privately owned herds, and according to Du Toit, a similar technique is employed in Zimbabwe. “In Zimbabwe, mass dehorning is not financially achievable for the larger populations and dehorning of selected rhinos is therefore undertaken opportunistically,” he said, adding that rhinos are more likely to be dehorned if they live in particularly high-risk areas, or if they must be sedated anyway for other reasons.

Another contentious issue is whether dehorning actually deters poachers. Berger, in a 1993 paper published in Conservation Biology, suggested that poachers do not discriminate among rhinos based on the size of their horns, meaning even rhinos with stumps could be targeted.  This conclusion may have some support. Janet Rachlow, a conservation biologist at the University of Idaho and one of Berger’s former Ph.D. students, helped manage a population of mostly dehorned white rhinos in Zimbabwe’s Hwange National Park in the 1990s. Normally, the herd was guarded by armed rangers; however, a budget shortage forced the park to scale back its security, and, as a result, most of the rhinos were poached anyway.

“When you think about the effectiveness of dehorning, you have to think about it in kind of a cost benefit ratio,” Rachlow said. For poachers, the cost is the risk of being shot by a ranger and the benefit is the value of the rhino horns, which tends to increase with the size of the horn. Rachlow said dehorning reduces the benefit of poaching by decreasing the value of the horns, but the technique is most effective when paired with a high cost in the form of heavy security.  The theory is that poachers are less likely to risk their lives shooting rhinos if the reward isn’t as great.

“My feeling is that dehorning in and of itself has not proved effective in Zimbabwe or in Namibia or South Africa,” Berger said, “and protection has been bolstered mostly through very strong anti-poaching measures.” Other experts agree that dehorning without extra security is not as effective. Statistics published in Du Toit and Anderson’s paper, as well as Taylor’s report, suggest that dehorning is most successful in heavily guarded areas.

The controversy surrounding dehorning makes its future uncertain. “I think there’s a limitation to how much you can do just by using a protectionist kind of situation,” Taylor said. This year, nearly 900 rhinos have been poached in South Africa alone, he said.  Du Toit added that issues such as limited funding and the difference in poaching rates from country to country make it difficult to say if dehorning will be expanded as an anti-poaching tool.  Both Taylor and Du Toit feel that the international community should consider other options, such as conducting economic analyses of the horn trade and taking steps to crack down on the global demand for rhino horns.  If successful, such measures could reduce the need for methods like dehorning.

“I think it would be a sad time if people could not see rhinos intact,” Rachlow said. “As important as it may be to dehorn rhinos to keep them alive, it would be a really sad future, a really sad statement on our decisions as humans, if we have to dehorn rhinos in order to have them be able to survive.”

About the Author

Chelsea Harvey

Chelsea Harvey is a recent graduate of Auburn University, where she received a B.S. in zoology, as well as minors in English and Spanish. Unable to choose between her love of science and her love of writing, she spent most of her free time as an undergrad working for her campus newspaper while simultaneously memorizing hundreds of scientific names for class. Outside of SHERP, her interests include playing music with friends, traveling and keeping up with international affairs.


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