Poachers have since slaughtered 105 rhinos in Zimbabwe, with dozens more probably killed but never found by rangers. That compares to an average annual poaching of two to five rhinos in previous years, almost all by local farmers for meat.
"We were caught with our knickers around our ankles," said Graham Child, Zimbabwe's director of National Parks and Wildlife.
In the 18 months since, Zimbabwe has been literally shooting to kill in a brutal and unprecedented war with invading poachers. In what it regards as an armed confrontation, Zimbabwe has enlisted former guerrillas as paramilitary rangers to track down and confront well-armed poaching gangs.
Under "Operation Stronghold," rangers calling themselves the "Rhino Liberation Front" have killed 11 poachers in shootouts in 18 months. Thirteen others have been captured and brought to trial, Child said.
Zimbabwe's aggressive anti-poaching efforts are being watched closely throughout Africa, for Zimbabwe represents the last stand for the black rhino.
Poachers have swept through Africa like locusts over the years, wiping out rhino populations from the Horn of Africa south through eastern and central Africa. They have exterminated the black rhino in Uganda, and nearly so in the Central African Republic, Chad, Rwanda, Malawi, Angola and Mozambique.
Of the roughly 65,000 black rhinos in Africa as recently as 1970, only an estimated 4,500 remain - just under 2,000 of them in Zimbabwe.
Unmolested in the past because of Zimbabwe's seven-year liberation war and
because rhinos were plentiful elsewhere, the rhinos here have by default become the poachers' only remaining targets.
Protecting them are the new rangers, most of whom fought bush wars against white-ruled Rhodesia in the 1972-79 liberation war. Their guerrilla skills are now put to good use in the vast Zambezi Valley, once a guerrilla infiltration route.
"It's one of the few positives of war," Child said. "These chaps are familiar with the type of drastic tactics that are required."
The poachers have proven to be a formidable enemy. Operating in gangs of up to 50 armed men, they slip in canoes across the Zambezi River from Zambia into Zimbabwe. They carry Czech and American-made hunting rifles to use on the rhinos and G-3 and AK-47 military assault rifles to use on the rangers.
All 11 poachers killed since 1985 have been Zambian nationals, Child said. Their deaths have strained relations between the two countries, with Zambia saying the poachers should have been arrested and turned over.
Zimbabwe, however, has accused Zambian government officials of harboring and aiding poachers in return for a cut of their profits.
To provide the ranger patrols with equipment, conservationists in Zimbabwe organized the Rhino Survival Campaign in October. It has so far raised 160,000 Zimbabwe dollars ($100,000 U.S.), according to chairman Dick Pitman.
Pitman said he began the campaign because one look at the map made it obvious that Zimbabwe had become the only place left for the poachers to find rhinos in adequate numbers. In Zambia, just north of Zimbabwe, poachers had reduced the rhino population from 3,000 10 years ago to 300 now.
"They had just moved south and exhausted Zambia and we were next on the list - and the last on the list, I'm afraid," Pitman said.
"They used to stay clear of us because they knew they'd be shot at. But there just aren't any rhinos left for them anywhere else."
To combat the poachers, Zimbabwe passed a tough new poaching law this spring. It raises the penalty for poaching to five years and/or the equivalent of $9,400 for a first offense and seven years and/or $22,000 for a second offense. The new law also requires compensation payment of $9,400 per rhino killed.
Poachers who have been arrested say they make the equivalent of $220 a day, Child said. That is a fraction of the retail price for rhino horn - which sells for up to $25,000 a kilogram - but about two-thirds the average annual salary in Zambia.
"Things must be desperate in Zambia," said Esmond Bradley Martin, a Nairobi-based authority on rhino-horn trade. "Everybody from the prime minister on down is after them in Zimbabwe, but they still keep taking one hell of a risk."
For centuries, Asians have revered the horn for its reputed therapeutic properties. Martin said Chinese medical books from the time of Christ mention use of the horn, which is actually matted hair.
In East Asia, ground rhino horn is taken for fevers, depression, lumbago, typhoid, skin rashes and hemorrhoids. It is rarely used as an aphrodisiac, Martin said, despite legends to the contrary.
In the 1970s, the traditional Asian demand for the horn was augmented by the Middle East oil boom. Newly wealthy Arabs in Yemen were suddenly able to afford ceremonial, rhino-horn daggers that Arabs consider a symbol of male virility.
About half the rhino horns poached in Africa now go to satisfy the Yemeni market. New daggers sell for $500 to $1,000, with antique daggers selling for $12,000 to $15,000 each, according to Peter Jenkins, a rhino expert in Kenya.
Jenkins calls the slaughter "the most appalling destruction of a large mammal in the history of mankind." While Zimbabwe fights the slaughter by attacking poachers, Jenkins is leading a drive in Kenya to herd rhinos into wildlife sanctuaries.
Meanwhile, Martin has been attacking the rhino slaughter from yet another angle - the lucrative horn market. Since 1979, he has headed an international project aimed at both outlawing the rhino trade and reducing demand for the horn.
Martin has had some success in persuading Asian governments to ban or sharply reduce trade in rhino products - notably South Korea, Hong Kong, Macao and Taiwan. But those countries still permit old stocks of rhino horn to be sold.
Even so, Martin said, his group's efforts have helped reduce the amount of rhino horn leaving Africa from an annual average of about eight tons in the 1970s to about three tons in the mid-1980s. It takes about 350 rhinos to produce a ton of horn.
Martin's next goal is to cut the rhino-horn trade into Singapore, where both imports and exports of rhino products are still legal. He said Singapore is the world's largest port of entry for the Asian-rhino horn, with some African horn also passing through.
Together, the efforts of Zimbabwe, Kenya and Martin's group have at least slowed the rate of slaughter. Nonetheless, poachers are still killing every rhino they can find.