It’s not a keen-eyed owl, nor is it even a lion. Cue the drumroll, Earth’s most prolific predator is… us, Homo sapiens.
At least humans, as we are today, are highly industrially competent and capable of using and modifying animals on a massive scale.
And in research published today in Communications Biology, the numbers are staggering. Industrialised humans target many times more species for food or other uses.
Within similar geographic ranges, the study found humans target 80 times the number of vertebrate species for food than lions; and 113 times the number preyed on by great white sharks.
When all uses of ‘prey’ are considered – in this case, the targeting of any individual animal that removes it from its wild population – humans exploit about 300 times the number of species as comparable predators.
“We wanted to approach the idea of humans as predators differently than… fisheries scientists or wildlife biologists… who don’t really consider humans as predators, though evolutionary anthropologists do sometimes,” says the study’s co-lead author, Professor Chris Darimont.
The University of Victoria (Canada) conservation scientist considers the question of which species a newcomer to Earth would consider the “stand out” among all others.
“We expected humans would be, but didn’t know the details,” he says.
The extent of humanity’s accomplished predation is most clearly demonstrated by comparisons with other taxa – categories of related species. The study found humans actively use 2 in 5 known species of ray-finned fishes, almost half of bird species, and a quarter of mammals and cartilaginous fishes (like sharks and rays).
‘Use’ extends beyond capturing prey for a person’s own nutrition, but for use in other agricultural practices, as pets, for medicine, clothing production, trophy hunting and collection.
The impact of this is profound. Human use of other mammals, amphibians and cartilaginous fishes put most species within these classifications at risk. In total, human exploitation puts 40% of targeted species under a conservation cloud.
Human impacts are not limited to the direct use of animals either.
Take the jaguar.
The research found humans use 300 times as many vertebrate species as the charismatic big cat over a similar geographic area, but also target every species preyed upon by jaguars.
So human impact on threatened species cuts two ways: either human overconsumption directly reduces numbers, or it directly competes with species for vital food sources.
Humans are disrupting predator diets
The pet trade is also a substantial contributor to animal exploitation. Alone, it contributes to more than half of the exploitation of all land-based species.
“Capturing species for the pet trade, which we consider the same as predation, is enormous [his emphasis]. On land, more species are captured for the pet trade than for food.”
On top of this, Darimont expects factors that weren’t considered as part of the research, such as land clearing and the introduction of feral predators, would result in a much larger disparity between humans and the next closest apex animals.
“Whereas predation evolved as a way to get nutrients and energy, humans have done so much more,” Darimont says. “Look how far we’ve come as predators.”
“Habitat loss, destruction, is arguably the most important stressor to animals on the planet… perhaps more influential than overexploitation.”
Rare invertebrates traded online pose risk to biosecurity
Corrective measures, or at least ones that reduce exploitation of animal species across the planet would include what Darimont calls “large-picture governance”. In one expression of this, giving greater agency to traditional custodians to manage land could help stem the rate of animal exploitation.
Ultimately, governments and societies need to consider how best to regulate the industrial use of animals by humans, should tens of thousands of vertebrate species continue to coexist on the planet.
“On one hand, if we continue doing what we do, it’s bleak: we will lose species and their roles in ecosystems,” Darimont says.
“On the other hand, if decentralised, placed-based management can take hold again after colonial and associated commercial structures interrupted it, the outlook is better.
“By and large subsistence hunters (before colonization) had a good track record in sustainability via cultural safeguards against overexploitation. Our hope that these ecological findings can be placed in the context of social, cultural, legal changes, from the UN Declaration of the Rights of Indigenous Peoples, and other country-specific processes.”
Matthew Ward Agius
Matthew Agius is a science writer for Cosmos Magazine.
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