On the morning of December 11, 2014, a Russian-built cargo plane touched down unannounced at Cabo Ledo, the military air base south of Angola’s coast-hugging Kissama National Park . Trucks were waiting on the runway.

Packed in the plane’s spacious hold were wooden crates containing wild game from South Africa—one of several shipments of ten species, totaling 215 animals, arranged by Angola’s Ministry of Environment.

As the containers were unloaded, one broke open, freeing a terrified eland that sprinted out across the airfield into the park.

The rest of the animals were trucked to enclosed sections of the park’s Special Conservation Area, apparently to be held there temporarily before being released in other reserves.

The 25,000-acre fenced area was originally set aside for animals airlifted from South Africa in 2000 in what was called Operation Noah’s Ark —a joint Angolan–South African project trumpeted as the start of a groundbreaking restocking of wildlife lost to Angola’s parks during its 27-year-long civil war, which dragged on till 2002.

When the story of the new, hushed-up transfer broke in South Africa’s Mail & Guardian , conservationists were outraged that nonnative species were once again being brought into the park, ignoring guidelines for wildlife reintroductions originally developed by the International Union for Conservation of Nature (IUCN) in the late 1990s.

Angola’s National Icon at Risk

Behavioral biologist Richard Estes was a vehement critic of the indiscriminate transnational mixing of species by Operation Noah’s Ark and says he’s “disgusted” that the same thing is happening again in Kissama.

Estes has conducted fieldwork in Africa for more than 50 years, including a year-long study of the critically endangered giant sable antelope , whose numbers hover at fewer than a hundred.

The spectacular coal-black males of this sable subspecies—revered as Angola’s national animal, a familiar icon on its currency and the tailfins of its airline—carry five-foot-long, scimitar-shaped horns, a foot longer than those of other sables.

Found only in Angola, they survive in two protected areas in the central highlands: Luando Strict Nature Reserve and Cangandala National Park .

In 2009 Angolan biologist Pedro Vaz Pinto pulled off a conservation coup by locating a small remnant population and starting a captive breeding program in Cangandala, where the herd has grown to about 30, helping to pull this legendary creature back from the brink.

Estes says it’s “totally unacceptable” that imported animals might be released alongside the sables.

The theileria/babesia group of protozoal parasites carried by many South African game species can be lethal for them. Symptoms of acute lethargy—drooping ears and lagging behind the herd—are followed by major organ failure and death within days.

View Images Nyala are among nine nonnative species recently shipped from South Africa to Angola’s Quiçama National Park. These antelopes compete aggressively for vegetation sources, threatening the park’s bushbuck population. Photograph by Richard du Toit, Corbis

The IUCN guidelines stress the need for comprehensive risk assessment before any translocation is undertaken, citing “the record of species moved outside their indigenous ranges that have become invasive aliens, often with extreme adverse impacts.”

Of the 2014 arrivals—kudu, impala, zebra, hartebeest, blesbok, wildebeest, oryx, waterbuck, nyala, eland—all but eland are alien to Kissama. The nyala is known to compete aggressively for browse with bushbuck, a species that’s abundant in the park and will now be at direct risk.

Whose South African Animals, and Why So Secret?

The source of the South African animals remains murky. Tipped off that Nico Roux, a longtime game trader in South Africa’s North West Province was involved in the transfer, National Geographic contacted him.

“The animals belonged to Miguel Ferreira,” Roux said, adding that “he only rented our game facility for the keeping and caretaking” of the animals before they were shipped. (Ferreira, of Exotic Game Breeders in South Africa’s Limpopo Province, was identified in the Mail & Guardian story as the game rancher who supplied the animals for the airlift.)

When asked if the animals indeed had come from his herds and who had paid for them, Ferreira refused to answer, invoking client confidentiality.

But, he said, “everything on my side was totally aboveboard.”

Nothing about this airlift, however, was aboveboard.

View Images Blesbok, native to South Africa, are another antelope alien to Angola. Biodiversity researchers fear this newly introduced species could become invasive. Photograph by James Hage, Robert Harding World Imagery/Corbis

On the Angolan side, no announcement was made about it, nor was there an admission that it even took place.

Repeated attempts to reach Fátima Jardim , the environment minister, or any of half a dozen officials who report to her, yielded nothing.

Several South Africans, Namibians, and Angolans with direct knowledge insisted on anonymity, citing worry about compromising their government relationships or fear of reprisals.

Neither South Africa’s Department of Environmental Affairs nor Angola’s Ministry of Agriculture responded to questions about whether the translocation followed export-import protocols for wildlife, including inspection for diseases.

The Gleam of Tourist Gold

According to Ferreira and several sources who asked not to be named, the Ministry of Environment intends to introduce animals into some of the 16 parks and reserves it oversees.

Press reports in 2013-14 out of ANGOP, the country’s official news agency, described the Ministry of Environment’s plans to rebuild Angola’s conservation areas using revenue from ramped-up tourism.

ANGOP reported that Bicuari National Park , in the southwest of the country near Lubango, was initially targeted. Nearly denuded of game during the civil war and the uncontrolled poaching that followed, this largely empty woodland area was singled out for ecotourism efforts that “may provide revenues.”

In March of this year, a provincial official announced that at least a million dollars will be “invested in revamping ecotourism” there, starting with the construction of 20 bungalows, with another 35 to be “added in the second phase.”

Sources say that plans were initiated last fall to bring in a wildlife shipment from Namibia to Bicuari National Park.

Could Cangandala National Park, one of the two last redoubts of the giant sable, be next?

"The ministry knows very well how important the survival of this animal is to the Angolan people,” said biologist Vaz Pinto, adding that the government had “supported or led the various efforts to ensure the breeding and recovery of the species in situ.”

But, he said, turning giant sable habitat “into a zoo-park with additional animals would be against conservation best standards and international guidelines, be unsustainable and a touristic failure, and would probably destroy the giant sable’s chances for recovery—so I'm sure this won't happen.”