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International wildlife trade sweeps across ‘tree of life,’ study finds

  • About one in five land animals are caught up in the global wildlife trade, a new study has found.
  • The research identified species traded as pets or for products they provide, and then mapped the animals’ home ranges, identifying “hotspots” around the world.
  • The team also found that nearly 3,200 other species may be affected by the wildlife trade in the future.
  • The study’s authors say they believe their work could help authorities protect species before trade drives their numbers down.

Watching a helmeted hornbill (Rhinoplax vigil) swoop through the canopy of a tropical forest sits atop the bucket list of many bird lovers. The prodigious bird cuts a striking silhouette against the sky with its bulging casque fused to its beak.

But the swiftly accelerating demand, especially in China, for baubles carved from the ivory-like material of their casque has diminished the chances of seeing helmeted hornbills throughout their habitat in Southeast Asia — so much so that the IUCN now lists the species as critically endangered.

“Animals are valuable on the market because they have something special — for example, brightly colored birds are in demand, as are animals that are a source of ivory,” Brett Scheffers, an ecologist and assistant professor at the University of Florida, said in a statement.

Java sparrows for sale at a bird market in Purwokerto, Java, Indonesia. Image by Gabby Salazar.

Shifting tastes for products and pets that come from the wild are having a sweeping impact on the vertebrate species that stalk, wriggle or fly over Earth’s surface, according to a recent analysis led by Scheffers and his colleague at Auburn University, Brunno Oliveira. The worldwide wildlife trade has ensnared around one-fifth of amphibians, birds, mammals and reptiles, the study found. That’s 40 to 60 percent higher than earlier estimates, the authors write.

The wildlife trade has caused more species extinctions than any other factor save habitat loss, so addressing why these animals are in such high demand will be vital to saving the nearly 5,600 species currently traded across borders, the authors say. But the study, published Oct. 4 in the journal Science, also reveals that another 3,196 species could face the threat of extinction as the wildlife trade expands to encompass products from relatives of today’s sought-after species.

“If one species is traded, chances are its evolutionary cousins are also traded,” Scheffers said. “Once we discovered that pattern, we could develop a model that would predict which species would likely be traded in the future, even if they aren’t traded now.”

A young helmeted hornbill. Image by Doug Janson via Wikimedia Commons (CC BY-SA 3.0).

The tentacles of the wildlife trade reach far, infiltrating 65 percent of all vertebrate families.

“Once one traded species is exhausted, species with similar traits will become the target of trade,” Scheffers said. “If we run out of one species of bright yellow bird, we move on to the next one most similar to it.”

Scheffers and his colleagues mined lists from the IUCN and the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) to pick out traded species among the roughly 31,500 vertebrates contained in these databases.

White-rumped shamas for sale in a bird market in Yogyakarta, Java, Indonesia. Image by Gabby Salazar.

They then looked at the ranges of the 5,579 traded species they identified, pinpointing a number of “hotspots” with the densest concentrations. These areas closely tracked the overall number of species living in different regions, with many of the hotspots turning up in the tropics.

These hotspot maps “are an important first step,” the authors write, pointing scientists and authorities to places where they should focus efforts on stamping out wildlife trade that’s potentially driving the most species toward extinction.

In a related finding, a separate study that also drew on CITES data, this time in the United States, found that countries that were the biggest source of legal wildlife products also accounted for the most illegal products confiscated by U.S. authorities.

Inspection of a legal shipment of animal pelts. Image courtesy of U.S. Fish and Wildlife Service – Northeast Region via Wikimedia Commons (Public domain).

Understanding where the wildlife trade could have its greatest impact in the future could shift current approaches to protecting vulnerable species, Scheffers said.

“Wildlife conservation is often reactive. Protections are put in place once a species is in danger, not before,” Scheffers said. “A species might not be of concern today, but as our study shows, that can change with shifts in supply and demand.”

Banner image of a hornbill by Charles Ryan/Sticky Rice Travel


Bager Olsen, M., Geldmann, J., Harfoot, M., Tittensor, D., Price, B., Sinovas, P., . . . Burgess, N. (2019.). Thirty-six years of legal and illegal wildlife trade entering the USA. Oryx, 1-10. doi:10.1017/S0030605319000541

BirdLife International. (2018). Rhinoplax vigil. The IUCN Red List of Threatened Species 2018: e.T22682464A134206677. doi:10.2305/IUCN.UK.2018-2.RLTS.T22682464A134206677.en. Downloaded on 06 October 2019.

Scheffers, B. R., Oliveira, B. F., Lamb, I., & Edwards, D. P. (2019). Global wildlife trade across the tree of life. Science, 366(6461), 71 LP – 76. doi:10.1126/science.aav5327

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