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Dye and Poison Stop Rhino Poachers

This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American


What do gold, platinum and rhino horn have in common? They are among the most expensive materials in the world – with rhino horn being the leader of this group. In late 2011, according to National Geographic Magazine, its Vietnam street price was between $33 and $133 per gram. In South Africa, it currently costs around $65 per gram – this is three times as much as a whole South African white rhino. No wonder rhino horn poaching is continuously increasing, with 333 poached South African rhino in 2010, 448 in 2011 and a total of 668 in 2012. The South African government’s latest statistics show that alone this year until March 15, 158 white rhinos have already been poached.

This high demand for rhino horns does not come out of the blue: In many Asian countries, especially in Vietnam, rhino horn powder is used to cure diseases like cancer or used to treat hangovers, improve concentration, and also as an aphrodisiac. However, there is absolutely no scientific evidence this actually works. According to the wildlife trade monitoring network TRAFFIC, more than 50% of Asians caught in South Africa in 2012 were Vietnamese citizens. As a matter of fact, there even exists a Youtube video from 2008 where Vietnamese diplomat Vu Moc Anh accepts a poached rhino horn delivered right to the Vietnamese embassy in South Africa.

In order to prevent poaching preemptively, the Rhino Rescue Project (RRP) was born. Its founders Ed and Lorinda Hern of the Rhino & Lion Nature Reserve in Krugersdorp developed together with veterinarian Charles van Niekerk a device that injects red dye into rhino horns. Yes, it is exactly the kind of indelible dye that is used for ruining bank robbers’ prey and tagging the thieves. RRP’s spokeswoman Lorinda Hern didn’t want to share the exact name of the product due to security reasons, but it is known that it works similar as industry products like Disperse Red 9, which also goes under the name of 1-methylamino anthraquinone.


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Disperse Red 9 is a red powder that, when combined with water, will turn into a highly visible purple liquid. That liquid can usually not be washed off with water, soap or alcohol. The infusion device soaks a rhino’s horn under high pressure. Unlike other horns, rhino horns do not have a bony core but consist entirely of keratin. These fibrous scleroproteins are bundled up like very tightly pressed hair, and they form a very tough horn. Thanks to this fibrous anatomy, they can be soaked with the dye from inside without being noticeable from outside.

Before the treatment begins, a veterinarian who supervises the whole procedure must immobilize the rhino. Hence, one member of the otherwise changing RRP task force is always a veterinarian. South African veterinaries use etorphine, which is better known as “M99”. Etorphine is an opioid that is between 1,000 and 3,000 times as potent an analgesic as morphine. According to a paper by Markus Hofmeyr, the head of Veterinary Wildlife Services at South African National Parks, M99 is routinely used for immobilizations on white rhinos. Regarding the negative effects of general anesthesia induced by M99, Hofmeyr writes: “White rhino are very sensitive to the respiratory depressive effects of the opioid drug (M99) and the animal is partially reversed soon after immobilization to counter this negative effect.”

In 2012, a male white rhino named Spencer didn’t survive RRP’s treatment. It didn’t wake up from general anesthesia. Brett Gardner, a veterinarian of the Johannesburg Zoo, was present as an independent observer, as he is not directly involved in the project. He wanted to see the treatment to determine the viability of the procedure for the zoo’s rhinos, he told me. The veterinarian adds: “I tried to assist but unfortunately Spencer had underlying medical conditions and was unable to respond to the CPR treatment.” Gardner still wants to use the procedure to treat the zoo’s rhinos. He is sure “that the rhinos in the zoo are at risk.”

Drilling Holes and Infusing Anti-Bank Robbery Dye

After a white rhino has been anaesthetized, van Niekerk and his team start the actual treatment by first drilling a hole into both of the rhino’s horns. They use an ordinary driller from a DIY market for that. Before that, they pour the dissolved red dye into a 2-foot high metallic cylinder with a diameter of about 4 inches. They then close it firmly with a metal cap and put it under hydraulic pressure. The conservationists, led by Lorinda Hern, then plug metal connectors with valves into the holes, screw them in tightly and link them - using rubber hoses - to valves attached to the metal cylinder. Finally, they open the valves and pump the red dye hydraulically into the horn until its fibrous structure is completely soaked from the inside. From the outside, the horn looks exactly like before. The general anesthesia lasts for about 45 minutes, and the actual infusion procedure usually takes no longer than 20 minutes.

White rhinos are the heaviest of the five extant rhino species, with males weighing around 5,000 lbs on the average and females around 3,700 lbs. Therefore, during the treatment, the conservationists need to roll over the immobilized animal every 7 minutes – otherwise its organs would be squeezed by its own body weight. Furthermore, they block the rhino’s ears with cotton wool in order to reduce its stress level during the drilling.

Purposely Poisoning Horn Consumers

Aesthetically speaking, Van Niekerk’s device is reminiscent of typical exterminators’ pest control spray systems. In fact, there is a connection between the two types of devices: The liquid dye is not just dye. It is actually a mixture between the bright pink dye and an ectoparasiticide, which normally is used for protecting rhino against ticks. In this case, however, the purpose is not to protect the rhino against ticks but to poison rhino horn consumers. The purpose: Discouraging the (typically) Asian clients to buy the horn and to prevent poaching in the first place. If they consume RRP-treated horn powder, they will heavily suffer from nausea, stomach-ache and diarrhea. The effects are non-lethal but harmful to humans, which sparked off a debate on the ethical correctness of the procedure. Is it ethically correct to poison already-ill people who have been tricked by rhino horn traders?

To ox-peckers that feed on rhino ticks, the mixture is absolutely harmless, claims Susan Walley, spokeswoman of RRP.

Unlike dye packs, a treated rhino horn doesn’t react chemically – the dye will never explode. It does, however, show up on x-ray airport security scanners, even after a horn has been ground to powder. Combine this with the ill-making effects of the ectoparasiticide and voilà: the horn is practically useless to poachers, because it cannot be sold anymore.

The Herns and Dr. van Niekerk sell their services to nearby, privately run wildlife reserves, such as “The Savannah Africa”. Its owner, Renee de Jong Hartslief, has two white rhinos, a 10-year-old male and an 11-year-old, pregnant female. Earlier this year, she has had both rhinos be treated by the RRP team, for a cost of around $900 each. She feels vulnerable to poachers although her property is rather secluded. But she already had a frightening experience in the past: “We have had an incident 3 years ago, where a helicopter landed where the rhinos were grazing at the time, but the lodge manager arrived and the helicopter took off.” South African rhino and elephant poachers typically attack from helicopters, because it is a quick and relatively silent way. De Jong Hartslief managed to track the helicopter pilot but was not able to prove his intentions.

Fighting the Poachers with Patrols, GPS, Dehorning and Drones

There are other anti-poaching techniques, but most of them are reactive and cannot prevent the poaching in the first place. Typically, private reserve owners like de Jong Hartslief and the Herns rely on anti poaching units (APUs), i.e. armed troops that comb their reserves on foot or using helicopters or quads. Their patrols sometimes end in violent encounters with the poachers, like at the end of March this year, when three alleged poachers were killed by Kruger National Park’s game rangers.

Another controversially discussed option is dehorning the rhinos. During that procedure, the animals are sedated, and their horns are cut off using chainsaws, without being hurt. The treatment costs between $620 and $1,000. London-based charity “Save the Rhino International” (SRI) reports only between 90 and 93 percent of a rhino’s horn is cut off during the procedure. What is left behind is a stub that is still of interest to the poachers. According to SRI, two years ago in Zimbabwe six rhinos have been killed for their stubs shortly after they had been dehorned.

As drones are making their way into civil use, some game reserve owners are now also using them for game surveillance. Earlier this year, The Huffington Post reported that India is deploying drones over the Kaziranga National Park, which has between 15 and 20 rhinos poached per year. It is known that at the end of 2012 the WWF received a $5 million grant from Google for buying and developing state-of-the-art surveillance systems, including drones. Currently, the WWF is testing the drones in Namibia and Nepal. It will use human-piloted drones and not their fully autonomous counterparts.

According to The Guardian, a South African farmer, Clive Vivier, is currently trying to get an allowance to deploy 30 surveillance drones over SA skies – 10 for the Kruger National Park and another 20 for spying upon other wildlife reserves. The 65-year-old farmer already received the permission by the US state department to buy Arcturus T-20 drones. The T-20 drone is silent and carries an infrared camera with HD resolution that enables the farmers to spot poachers at night. Now he awaits the civil aviation authorities’ approval. “We can see the poacher but he can't see us. We're good at arresting them when we know where they are,” he told the Guardian.

Since 2010, there exist also GPS-based solutions to track rhinos: South African company ProTagTor produces RF-Tags that are implanted into rhino horns using a similar procedure as van Nierkerk’s. Every 60 seconds, an implanted device reports its host’s position and an analysis of its movement data. Did the rhino run fast? Did it sleep more than six hours in a row? The ProTagTor device would interpret this as unusual behavior and send it as an SMS report to a central receiving station – which in turn would automatically alert nearby game rangers, so they could have a look at the rhino. Upon the owner’s request, the RRP team also implements GPS chips to track the rhinos. Unlike as it was reported by Popular Science, RRP does not always insert GPS chips but rather three microchips that help to identify each rhino.

A Fight Against Poachers, Veterinarians and Even Games Rangers

Susan Walley, RRP’s spokeswoman, pointed out to me another problem: Some South African veterinarians are corrupt and sell M99 to poachers. According to South African news outlet Independent Online (IOL), among them are former Kruger National Park’s veterinarians Douw Grobler and Johannes Gerhardus Kruger. M99 is strictly controlled and not sold to everybody. This is where the corrupt veterinarians come into play: they buy the M99 and sell it to the poachers. But why would poachers prefer anesthetics to bullets? Because darting the rhinos is more silent. And because shooting from a helicopter is not easy – a shot with the dart gun does not have to be as precise as one with live bullets. M99 is strong enough to completely immobilize a fully-grown white rhino within five minutes.

It seems that besides the actual poachers and the veterinarians providing them with M99, even some game rangers are involved. In the Great Limpopo Transfrontier Park in Mozambique, game rangers have been involved in killing a total of 300 rhinos between 2002 and today. The South African Times reports that 30 game rangers of the Limpopo are being charged for taking part in the killings.

So, what can be done to fight the rhino slaughter in South Africa? The RRP project is certainly an important step, because it is proactive instead of reactive. Today, as I am writing this, (statistically speaking) poachers killed two white rhinos in South Africa. Tomorrow another two will die, or even more. RRP-treated rhinos are currently not likely to be among them, as Walley told me: “Spencer is the only rhino we have lost to date, and we have already treated almost 150.” By the numbers, During my research for this piece, I have found no other technology as effective as this one.

Anyway, no matter the anti-poaching technologies used: 2013 is on the way to hit a new poaching record high. Van Niekerk’s anti-poaching treatment is simple yet impressive, but: in order to become fully effective, awareness must be raised among horn consumers. In late April, TRAFFIC launched a marketing campaign to sensitize cancer patients in Vietnam, claiming rhino horn powder is useless as medicine. I wonder what the next poaching statistics will look like.

Images: Paint Dog Films, via Rhino Rescue Project.

About Martin Angler

Martin W. Angler is a freelance science journalist, who specialises in how technology affects our lives. He was educated at the universities of Vienna and Bolzano. His work has appeared on BBC Future, in Neue Zürcher Zeitung, ZEIT Online, bild der wissenschaft and several popular scientific magazines. He also writes a tech column for ACADEMIA.

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