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Humans collectively prey on nearly 15,000 wild vertebrate species, roughly one third of all varieties on the planet

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A new study highlight's the extent of humanity's impact as a predator. Over a given range, humans take up to 300 times the amount of available prey versus wild predators.Michael Probst/The Associated Press

From great white sharks to Bengal tigers, top predators around the world have the reputation of being sleek, fast and surgically precise in their actions. They are consummate specialists, drawing from the environment exactly what they need and keeping the ecosystem balanced in the process.

Enter humankind, a different kind of predator that has adopted a strategy more like a contestant in a supermarket contest, madly racing down the aisles and emptying entire shelves to fill as many shopping carts as possible with everything and anything in reach.

That scathing characterization is bolstered by a quantitative study of humanity’s impact as a global predator. While it should come as no surprise that humans play an outsized role in extracting resources from the natural world, the hard numbers reveal a level of rapacity that beggars the imagination.

According to the study, published Thursday in the research journal Communications Biology, humans collectively prey on about 15,000 wild vertebrate species, or roughly one third of all varieties on the planet. Over a given range, humans also take up to 300 times the amount of available prey versus wild predators for which good data are available, including leopards, lions and wolves, among others.

All of this comes alongside the fact that we derive most of our animal-based protein from cows, pigs and chickens which we raise and consume on an industrial scale. Domestic livestock are not included in the study’s staggering tally.

The study also does not distinguish between animals that are preyed on to be eaten and those taken for other purposes, such as for medicines or exotic pets. The pet trade alone accounts for more than half of all hunted species on land. But whether they are eaten or not, all uses lead to the same result, which is taking animals and their genetic diversity out of the ecosystem.

“It’s absolutely astonishing at a global, taxonomically broad scale how unique human predators are,” said Chris Darimont, a conservation scientist at the University of Victoria, who led the research. “We have an ecological influence that tends to be extraordinary.”

Significantly, about 40 per cent of the species in the study are considered threatened, which further underscores that the amount of human harvesting of wildlife from the environment is unsustainable and undermines conservation goals that the majority countries have pledged to uphold.

Dr. Darimont, whose work is supported by the Raincoast Conservation Foundation, a non-profit organization based in Sidney, B.C., said he undertook the analysis together with colleagues in Canada, Britain, the United States and Brazil at a time when it was difficult to conduct research in the field because of pandemic measures.

He added that the project began as a way to satisfy his own curiosity about humanity’s “predatory niche” relative to other species. By design, the approach taken to answer that question makes no special assumptions about humans, as though the study were being conducted by an ecologist from another planet who is trying to assess the role of humans as one of many species on Earth.

“We were asking kind of a basic, fundamental question to have a better understanding of the nature of the beast, so to speak,” Dr. Darimont said.

For their analysis, team members combed through the database of the International Union for the Conservation of Nature, which includes a “use and trade” category in its descriptions of thousands of species around the globe.

The results highlight that the most important factor behind humanity’s overwhelming success as a global predator has little to do with skill or even cunning weapons, such as high-powered rifles, that give individual human hunters a lethal reach beyond their physical attributes. Rather, fossil fuels and related technologies of the industrial era have allowed people to travel by land, water and air to virtually any location on Earth at speeds unavailable to any other species, and simply take whatever can be found from ecosystems that range from the densest jungles to the most remote locations on the high seas.

“What we didn’t know before is the extent to which we humans do this and what this has been doing to wildlife populations,” said Liana Zanette, a professor of biology at Western University in London, Ont., who was not involved in the analysis. “That is the value of this excellent study, which has collated the global data in a very rigorous way.”

Dr. Zanette said that humans affect wildlife not only through the animals they capture or kill, but through the fear of humans that our extreme predation instills, which influences animal behaviour.

Unlike predators whose numbers dwindle if prey populations are in decline, humans are separated from the food web and its cycles, which means their impact can grow even as the species they prey on diminish.

William Ripple, a professor of ecology at Oregon State University, said that the global overexploitation of animals as documented in the study “is a symptom of ‘ecological overshoot’ involving a history of drastic increases in human population, consumption, and advanced technologies.”

While the results make for grim reading, Dr. Darimont said, “there are plenty of bright spots about how various Indigenous societies have exploited species sustainably over millennia to guide the way.”

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