When Richard Ruggiero first saw the gold mine from the air, he was reminded of one of Dante’s circles of hell. In the midst of Gabon’s Minkebe National Park—a huge, protected, 3,000-square-mile area—there was “a gaping hole in the forest more than half a mile wide and long.” On the ground, the mine was a “noisy, crowded, polluted, lawless confusion”—a hub of 6,000 miners, prostitution, drugs, and arms trafficking. And amid the chaos, Ruggiero and colleagues found caches of ivory, high-caliber weapons, and huge, grey carcasses. That’s when they knew that the forest elephants of Minkebe were in trouble.

Contrary to popular belief, Africa isn’t home to just one species of elephant—but two. The savannah or bush elephant is the familiar one that tourists see on safaris, and that turns up in nature documentaries. The forest elephant is smaller, darker, straighter of tusk, and rounder of ear. Its ivory, which is extra hard and has a pinkish tint, is also particularly prized.

At the turn of the century, forest elephants had already been decimated by poaching, and of the 80,000 estimated survivors, half lived in Gabon. Minkebe was meant to be a sanctuary for them—far from Gabonese villages in the south, bordered by swampy terrain on the north, and just too large and isolated for poachers to sweep. “People took their eye off the ball because they thought the park was safe,” says John Poulsen from Duke University.

The cost of that complacency became clear when the gold mine was discovered. The Gabonese government sent the military to close the mine and root out the poachers, but the damage had already been done. In 2013, following a quick pilot study, scientists estimated that between 50 and 100 elephants were being killed daily, and that between 44 and 77 percent of Minkebe’s elephants had already been slaughtered since 2004.

“If we do not turn the situation around quickly, the future of the elephant in Africa is doomed,” wrote Lee White, the British-born head of the Gabon National Parks Agency. “Our actions over the coming decade will determine whether these iconic species survive.” Now, after a more rigorous survey of the elephant numbers, White, Poulsen, and others have found that their work is even more urgent than they had realized.

Savannah elephants can be counted from the air, but forest elephants are so elusive that biologists literally have shit to go on: They have to trudge through the undergrowth, counting piles of elephant dung. They then used two separate methods to convert dung densities into elephant numbers—one that estimates the rate at which dung decays, and another that also factors in the effect of rainfall. Satisfyingly, both methods led to the same conclusions. Depressingly, those conclusions were worse than the team had expected.

They estimated that in 2004, there were between 32,800 and 35,400 elephants in Minkebe. But in 2014, there were just 6,500 to 7,400 left. In just one decade, poachers had killed around 25,000 forest elephants—between 78 and 82 percent of the park’s population. “It was an enormous shock,” says Poulsen. “To be quite honest, I would have guessed that other studies had overestimated the loss. I was expecting a decline, but I didn’t expect it to be that high.”

The dung decline fit with other lines of evidence. Guards have stumbled across hundreds of actual carcasses. Poachers have been caught with rifles and tusks. A genetic study traced the DNA of seized ivory back to elephants living in the Minkebe region.

That this should have happened in Gabon is a tragedy. The country has among the best conservation policies in Africa. They have set aside large tracts of protected space. They pay wildlife rangers on time. In response to the Minkebe crisis, President Ali Bongo Ondimba raised the status of the forest elephant to “fully protected”, doubled the budget of the National Parks Agency, created the National Park Police, passed new legislation to criminalize commercial ivory poaching, and increased prison terms for ivory traffickers. In 2012, he set fire to the country’s entire stockpile of seized ivory—the first such act for a Central African country. For three days, a 10,000-pound pyramid of tusks burned in symbolic defiance.

“Although elephants can and do move away from poaching, at some point there is nowhere left to go.”

But most of the poachers aren’t coming from Gabon. The dung surveys suggest that they are pouring in from Cameroon to the north. “There are now military posts along the border, but it’s big and poachers eventually find a way to slip through,” says Poulsen. “And though military ecoguards patrol the park, poachers are often more familiar with the forests than the military, who come from the capital city.” Heading to to places where the elephants gather, like fruiting trees, clay licks, and water sources, they gun down the animals with automatic weapons, and slice off their faces with chainsaws.

These deaths are tied to less grisly activities. “The biggest threat to forest elephants is commercial logging,” says Andrea Turkalo from the Wildlife Conservation Society. “It attracts people in search of work which puts even more pressure on the wildlife.” Logging also means roads, and roads provide access to hunters. It’s telling that poaching in Minkebe is lowest in the park’s southern end, where the closest Gabonese road is 50 kilometers away. By contrast, the north-eastern corner, which is 6 km away from a main road in Cameroon, had been nearly emptied of elephants. Again, there’s only so much Gabon can do on its own.

“Although elephants can and do move away from poaching, at some point there is nowhere left to go,” says Fiona Maisels from the Wildlife Conservation Society. “The international nature of both poaching and elephant movements means that trans-border protection and collaboration between states is absolutely key to maintaining elephant populations.”

And ultimately, as long as people are buying ivory, poaching will continue. Ivory prices at nearby trading posts have increased ten-fold since 2005, and the ivory from a single elephant is worth four years’ salary in Cameroon. “Poachers are often just poor villagers, who are armed by cartels with resources,” Poulsen says. “The Gabonese government is working hard on reducing the supply of ivory, but other countries need to work on the demand.” Last December, China—the country where most poached ivory ends up—led the way by vowing to shut down its domestic ivory trade in 2017. “That will go a long way,” says Poulsen.

He argues that the International Union for the Conservation of Nature, which classifies the planet’s species according to their risk of extinction, needs to consider forest elephants separately from their savannah cousins. Although the two used to be thought of as closely related subspecies, they are clearly distinct. They’re as genetically different from each other as Asian elephants are from extinct mammoths.

To Poulsen, lumping the two species together is a political move. “There are a few southern African countries that have successfully protected the savannah elephant, and want to sell some of the resulting ivory,” he says. That’s possible because the elephants are classified as “vulnerable”—translation: they’re in danger, but not too much danger. But if the two species were separated, the forest elephant would almost certainly move down two ranks to “critically endangered”, and the savannah elephant might be downgraded too. Ivory sales would have to stop.

That decision, Poulsen says, is probably inevitable. “The scientific evidence means that they’ll eventually be recognized as separate species, and we’ll need to deal with their conservation separately.” And despite the grim outlook from his work in Minkebe, he isn’t giving up. “As much bad news as we’ve been hearing, I think people are paying attention and there’s more will to conserve the elephants. China’s ivory ban is good evidence of that. I’m optimistic that we can move forward and save both species.”