"The tree of life is being pruned by human activities at an unprecedented rate."

This is the conclusion of a team of researchers in the journal Science. Around 18 percent of all land vertebrate species on Earth are touched by the wildlife trade, whether that be for luxury foods, medicinal parts, or as pets. This is 40-60 percent higher than prior estimates, and is one of the most marked drivers of vertebrate extinction risk globally. 

"Each year, billions of wild plants and animals are traded to meet a rapidly expanding global demand, a demand so insatiable that, globally, US $8 billion to $21 billion is reaped annually from the illegal trade, making it one of the world’s largest illegitimate businesses," they write.

Using data from the Convention on International Trade in Endangered Species of Wild Flora and Fauna (CITES) and the International Union for Conservation of Nature (IUCN) Red List, the researchers evaluated the effects of the wildlife trade on over 31,700 vertebrate species. They found 5,579 species, roughly 18 percent of all the vertebrates included in their analysis, have been reported as traded, with 27 percent of mammals, 23 percent of birds, 12 percent of reptiles, and 9 percent of amphibians globally traded.

In an attempt to foresee – and thus prevent – the future of wildlife trade, the team developed a model to predict which species currently untouched by the crime have a high chance of being traded in the future.

At first, such a crystal ball of wildlife trade seems implausible but the team says there is "nonrandomness" in the illicit business that makes some creatures more susceptible to smuggling than others. For example, species that share similarities to currently exploited species – the growing arapaima leather trade to replace pangolin leather in the US for example, or the rise in the trade of helmeted hornbills for their keratin horns, which are similar to ivory but softer and easier to carve into jewellery or ornaments. They also found large-bodied creatures are more traded than small-bodied, and wildlife traffickers target species that are distinctive with something unusual or eye-catching about them. 

In all, the team identified 3,196 at-risk species. "Although the footprint of trade spans all of Earth’s habitable continents, we uncovered a pantropical dominance in the trade for vertebrates."

The team admits combating wildlife trade is rife with complexity as many smugglers hunt illegally due to impoverished circumstances and selling to middlemen is a source of cash income. They suggest wildlife trade policies linked to transnational agreements in the hopes economic incentives for protection rather than exploitation can help local communities.

"Our assessment underscores the need for a strategic plan to combat trade with policies that are proactive rather than reactive, which is especially important because species can quickly transition from being safe to being endangered as humans continue to harvest and trade across the tree of life."