Wildlife Authorities Take Rhino Poaching by the Horns
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| Greater one-horned Asian rhinoceros. (Jessie Cohen/NZP) |
Forensic scientists are constantly developing new techniques to combat wily poachers. The extensive trade of rhino horn, which is illegally bought and sold by the pound, keeps forensic scientists on their toes.
All five rhino species—black, white, Greater Asian, Sumatran, and Javan—are endangered. Just a few decades ago, the world’s rhino population exceeded 100,000, but today there are less than 11,000. They have been decimated in part by habitat loss, but also as a result of indiscriminate poaching.
Rhino horn fetches a high price in China, where it is ground into medicinals, and Yemen, where it is carved into dagger handles. In the mid-1990s, when sanctions were imposed on Taiwan for rhino-horn trade, one pound of rhino horn could command more than $60,000.
In an effort to protect rhinos from the continuing demand for their horns and to prosecute poachers, wildlife authorities employ a powerful tool used in human criminal cases: DNA testing. Each rhino species has unique segments of DNA. In September 2003, The Central Police University in Taiwan decoded rhino mitochondrial DNA and identified those unique segments. That breakthrough led to new testing techniques that detect the presence of rhino horn in Asian medicinals and identify the species from whence the horn came.
Scientists can also determine a rhino’s species thanks to the unique structure of its horn. Rhinos do not have true horns: theirs lack the bony core found in animals such as antelopes and goats, and are instead made of keratin, the same substance that’s in our hair and fingernails. Chemical analysis of the keratin reveals the rhino’s former dietary habits—if it consumed mostly grasses, it was probably a white rhino. If it favored woody plants and herbs, it was most likely a black rhino.
Now it gets more specific. After scientists establish species, they can differentiate between populations within a single species; because each population has a slightly different range, they can then deduce the location of the rhino’s death. Scientists at the Institute of Zoology in London have developed a mass spectrometer technique to analyze samples of rhino horn for ratios of carbon and nitrogen, and from their results determined species. Next, they deduced where the rhinos had lived by matching the chemical ratios in the horns to a database of ratios of carbon and nitrogen in the soils, vegetation, and climates in specific rhino ranges.
Wildlife authorities use these cutting-edge techniques to pinpoint the origin of the horn to a small geographic area, like a reserve or national park. Armed with this knowledge, they can concentrate their efforts on the locations—and rhino populations—that most need their protection.
—Terry Dunn
ZooGoer
32(6) 2003. Copyright 2003 Friends of the National Zoo.
All rights reserved.
