In April 2010, poachers opened fire on the last known Vietnamese Javan rhinoceros. The animal—the final member of the subspecies Rhinoceros sondaicus annamiticus—died, and its horn was sawed off its body. In an instant, a lineage that likely once numbered in the thousands was extinguished.
The Vietnamese Javan rhinoceros was neither the first casualty of wildlife trafficking, nor the last. In species ranging from scaly mammals to brightly plumed birds, history threatens to repeat itself—and, according to a study published today in the journal Science, the world is headed for more of the same.
By mining the world’s foremost databases on wildlife trade, a team of conservationists has found that 5,579 species of mammals, birds, amphibians, and reptiles are now ensnared in the global market. As these animals are depleted, poachers and traders seeking similar goods will turn to their close cousins on the tree of life—a known replacement strategy that could imperil an additional 3,196 species not currently on the market, the researchers say.
If these predictions are accurate, close to 30 percent of all land-based vertebrates around today would be at risk of extinction from commoditization alone.
“This underscores the sheer magnitude of wildlife trade,” says study author Brett Scheffers, an ecologist at the University of Florida. “But knowing who is being traded and where is very powerful. We need a strategic plan to deal with wildlife…and now, we can at least make informed decisions.”
In both its legal and illegal forms, wildlife trade comprises a multibillion dollar industry that shuttles billions of plants and animals around the globe each year to meet demand for food, medicine, pets, and luxury items. No country is immune—and this lucrative market is now one of the biggest drivers of extinction worldwide.
Even among threats to biodiversity, wildlife trade is unusual, Scheffers says. While habitat destruction and climate change tend to fell species indiscriminately, he says, the economic impetus behind trade puts intense focus on specific animals, vaulting some species like Sunda pangolins and helmeted hornbills onto the list of critically endangered species within the span of just a few years.
But for the most part, data on this global phenomenon has been lacking. The calculations reported by Scheffers and his team dwarf previous estimates of the extent and impact of wildlife trade by 40 to 60 percent.
That’s in part because their study is the first to pool data from the two largest databases documenting traded species: the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) and the International Union for Conservation of Nature Red List of Threatened Species (IUCN Red List). The final tally showed that the wildlife market affects roughly 18 percent of the world’s 31,745 terrestrial mammals, birds, amphibians, and reptiles. And those are just the traded species we’re aware of, points out study author Brunno Oliveira, an ecologist at Auburn University at Montgomery.
“There are overlaps between these two sources of information...but also species that are missed in one or the other,” says Ana Benítez López, an ecologist at the Doñana Biological Station in Spain who was not involved in the study. “This approach is more comprehensive than what has been done before.”
But the study’s biggest innovation, Benítez López says, was taking its analysis beyond present day.
As populations of certain species dwindle, traders often find substitutes to keep pace with demand, casting wider and wider nets across the tree of life—and putting more animals at risk. Faced with declining Asian pangolin populations, for instance, poachers have recently turned their attention to species in Africa.
Preserving biodiversity requires transitioning from conservation’s typical reactive approach to one that’s proactive, Oliveira says. “And in order to be proactive, you have to know who is traded now, but also who has chances of being traded in the future,” Scheffers adds.
When Scheffers, Oliveira, and their colleagues scoured the 5,579 animals they’d already identified, they found that traded species tended to cluster in families and share relatively recent common ancestors. “Trade isn’t random,” Scheffers says. “If one species is traded, chances are that its cousin is, too.”
That’s because wildlife trade isn’t driven by specific species, but by desirable traits—like plumage, fur, or scales—that are often shared between closely related animals, Scheffers says. The team also found large-bodied species to be particularly popular commodities.
The researchers used these patterns and more to pinpoint an additional 3,196 animal species, most of which are reptiles, likely to be exploited by the global wildlife market in the future. That brings the grand total to 8,775 species at risk of extinction from trade.
Because these vulnerable species are often cut from the same evolutionary cloth, these potential losses wouldn’t just prune the tree of life—it could hack off entire branches, Benítez López says. That, she says, would cause biodiversity on the whole to plummet. “We could be headed for a world that’s more homogeneous,” she says. “There’s no way to get [those species] back.”
But Scheffers and Oliveira both hope that their predictions can help researchers and policymakers get ahead of the extinction curve.
In particular, conservationists could use the team’s data to prioritize populations and geographic regions most vulnerable to trafficking and trade, Oliveira says. Many of the animals on the team’s list are concentrated in tropical regions—known hotspots of biodiversity—that are already under threat from other human disturbances. Species shouldn’t need to be teetering on the brink of extinction to warrant interventions, he says.
The study’s predictions are sensible, and preemptive species protections are, in theory, a good idea, says Lynn Maguire, an environmental policy expert at Duke University. But actually implementing them, she says, would be “a very heavy lift politically and socially.” It’s hard enough to wrangle the attention and resources necessary to halt the wildlife trade that’s ongoing, let alone transactions that have yet to occur, she says.
And while evolutionary relatedness often guides where poachers and hunters look next, “you can’t always determine human whim,” says Leigh Henry, wildlife policy director at the World Wildlife Fund. As in any other market, demand for products can ebb and flow drastically on a near-daily basis. And the cultural triggers for species-specific surges can come from unexpected places: The international popularity of the Harry Potter franchise, for instance, is thought to have sparked a boom in the trafficking of pet owls.
Still, Maguire and Henry, neither of whom was involved in the study, laud the researchers’ efforts to bring attention to what has become an international threat to biodiversity.
“There’s no one approach that’s going to solve the problem,” Henry says. “We need to get ahead of the game and address species declines before they approach the point of no return.”