Part of the reason is the demand in Asia, where the horn is used in traditional Chinese medicine. A kilogram of rhino horn now goes for $60,000 on the black market. That's $1610 an ounce for the rhino horn. The rate of their decline is truly astounding: in the decade of the 1970s alone, half the world's rhino population disappeared. Today, less than 15 per cent of the 1970 population remains an estimated 10,000 to 11,000 worldwide.