This article is from Hakai Magazine, an online publication about science and society in coastal ecosystems. For more stories like this, visit hakaimagazine.com.
Some humans may be picky about food, but as a species we are not. Birds, bugs, whales, snails, we’re going to eat them all. But our dependence on wildlife goes well beyond mere food. From agricultural feed to medicines to the pet trade, modern society exploits wild animals in ways that surpass even the most ravenous and unfussy wild predator. Now, for the first time, researchers have attempted to capture a complete picture of how we use wild vertebrates, including how many and for what purposes. Research shows how great our collective impact on wildlife is.
Previously, scientists measured how much more biomass humans take from the wild than other predators. But biomass is only a fraction of the bigger picture, and the researchers wanted a fuller understanding of how human predation behavior affects biodiversity. Analyzing data from the International Union for Conservation of Nature, researchers have now found that humans kill, collect or otherwise use about 15,000 species of vertebrates. That’s about a third of all vertebrate species on Earth, and a distribution up to 300 times larger than that of the next largest predator in any ecosystem.
According to Rob Cooke, ecological modeler at the UK Center for Ecology and Hydrology and co-author of the study, the predators that give us the most competition are owls, which hunt remarkably diverse prey. The eagle owl, for example, is one of the largest and most widespread owls in the world. Not a picky eater, this owl will hunt up to 379 different species. According to the researchers’ calculations, humans record 469 species in an equivalent geographic range.
But according to Chris Darimont, a conservation scientist at the University of Victoria in British Columbia and co-author of the study, the biggest shock isn’t the number of species we’re impacting, it’s who Why we take them. The “ta-da result,” he says, “is that we’re removing or essentially hunting more animal species for non-food reasons than for food reasons.” And the largest non-food uses, according to the scientists, are in pets and pet food . “Things got out of hand there,” he says.
This general trend has some nuances. When it comes to marine and freshwater species, we mainly feed on them for human consumption. With terrestrial animals, however, it depends on which animal species it is. Mammals are mostly caught as food for humans, while birds, reptiles and amphibians are mainly caught to live in captivity as pets. Overall, nearly 75 percent of the land species that humans catch end up in the pet trade, which is almost double the number of species we eat.
The problem is particularly acute for tropical birds, and the loss of these species can have far-reaching ecological consequences. For example, the helmeted hornbill, a bird native to Southeast Asia, is caught primarily for the pet trade because its beak is used as medicine or carved like ivory. With their huge beaks, these birds are among the few species that can crack open some of the largest and toughest nuts in the forests they inhabit. Their disappearance limits seed dispersal and tree dispersal in the forest.
Another major difference between human impact on wildlife and that of other predators is that we tend to favor rare and exotic species, which is not the case with other animals. Most predators go for common species as they are easier to find and catch. However, people tend to covet the novel. “The rarer it is,” says Cooke, “the more that drives up the price, and so it can spiral and get into this extinction spiral.”
According to Cooke, human predation for the largest and most conspicuous animals not only threatens their unique biodiversity and beauty, but also the role they play in their ecosystems. Of the species that humans hunt, almost 40 percent are threatened. The researchers suggest that industrialized societies can draw on indigenous management models to find ways to manage and live with wildlife in a more sustainable way.
Andrea Reid, a citizen of the Nisg̱a’a nation and Indigenous fisheries scientist at the University of British Columbia, points out that humans have been fishing for millennia. “But the choices that shape industrial fisheries,” she says, such as how people consume fish caught far from their own homes, “contribute to the observed high impacts on fish species.”
If we want wild species — fish and others — to survive, we need to reframe our relationship with them, perhaps from predator to custodian, Reid says.
This article is from Hakai Magazine, an online publication about science and society in coastal ecosystems. For more stories like this see hakaimagazine.com.