As I wrote in The Trouble WIth Lions rhino poaching for horn has been going on a long time, and at one time, a hundred years or so ago, armed gangs were sent out to collect them in droves.
It is difficult to imagine how this trade will cease mainly because of the insatiable desire for rhino horn in Yemen and the Orient. Here is what I wrote about the traditional medicine beliefs and trade in the latter:
Two detailed reports from the early 1990s that were prepared for the Trade Records Analysis of Flora and Fauna in Commerce (more easily known as TRAFFIC) show how rhino horn is both used and sold in Korea and Taiwan. In 1993 author Judy Mills found that 60% of South Korea’s doctors believe that horn is an effective medicine and 79% believe it to be essential for a wide variety of ailments. In Taiwan Kristin Nowell and her colleagues, both of whom were locals who could conduct interviews as “patients” or “consumers” and thus obtain information unbiased by the doctors' or dealers'concerns about detection of potentially illegal activities reported that the medical community recognizes differences between rhino horn from Asia, and that from Africa. The former is about ten times as expensive, averaging over $60,000 per kilogram. They estimated that at least 10,000 kg of rhino horn were held in the thousands of licensed and unlicensed pharmacies during their study. Almost all of this was from African rhinos, and the total retail value, in 1992 was in excess of US$70 million. The most expensive items, far in excess of unprocessed Asian horn, were the antique carvings, becoming ever more valuable as pressure is brought to bear against the use or ownership of rhino horn for any purpose at all.
If rhino horn was that valuable in the 1990s, I cannot even guess what is is now worth if poachers are using helicopters. Depending on the machine helicopter time comes in at around $1000 per hour, and then there is the little matter of purchase price and the need for highly trained pilots.