Last year South Africa lost a record 448 rhinos to poachers—and that figure is just the number of carcasses authorities have found. The real number is probably higher. That’s at least one rhino killed every 20 hours, and the trend has continued into 2012, with 59 killed as of February 16. Over the last few years, sophisticated gangs have begun targeting the animals. The horns are smuggled to Asia and sold on the black market, where prices for rhino horn have skyrocketed. Geographic staff writer Peter Gwin recently traveled to Vietnam to learn how the horn is used in traditional medicine. His article appears in the March issue and he is the author of the upcoming eBook, Rhino Wars: The Violent Underworld of Poachers and Black Market Medicine, a comprehensive analysis of the current rhino poaching epidemic.

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