A ‘supersized’ ecological niche for humans
New research shows that humans have a much broader impact on biodiversity than other top predators, taking up to 300 times more prey species.
New research examining the ecological niche of humans shows that over one third of all vertebrate species on Earth are now being used by people. Humans thus have a much broader impact on biodiversity than other top predators, taking up to 300 times more prey species, and causing outsized impacts on natural ecosystems. As a consequence, almost 40% of exploited vertebrate species are now threatened by human use. So too are the ecological roles these overexploited species perform in ecosystems.
Publishing in Communications Biology, an international team of scientists across 14 institutions analyzed human ‘use’ data for 45,000 vertebrate species, including most known fish, mammals, birds, reptiles and amphibians. Whereas other top predators kill almost exclusively for food, ‘human predators’ have much more varied uses for their prey species. For land vertebrates, for example, the researchers were surprised to find that capturing terrestrial animals for the pet trade outnumbered food uses almost two to one.
“Humans have emerged as the planet’s most extraordinary predator, doing things that other predators do not. This includes commonly killing or capturing for reasons other than feeding themselves, as well as endangering thousands of prey species simultaneously,”says Chris Darimont of the University of Victoria and Raincoast Conservation Foundation.
How to manage or constrain such impacts has been the topic of recent negotiations under the Convention on Biological Diversity. “Human beings have gradually occupied a super-sized ecological niche”, adds co-author Boris Worm of Dalhousie University, “and our ability to manage our impacts has not kept pace with that growth. But new international commitments to protect 30% of the planet by 2030 may help nature to catch up with us.”
The new research also gives new insight into the risks of overexploitation, both from killing prey and live capturing them for the pet trade. Overexploited species tend to have different attributes – like large body size and a plant-based diet – compared with those not exploited or exploited sustainably. Indeed, the researchers find that humans are threatening a diverse and ecologically distinct set of species. Losing these species and the unique and potentially irreplaceable roles they play can bring deep changes to ecosystems.
“The unnatural selection of animals by human predators could lead to a range of repercussions across ecosystems. From the potential loss of large seed-dispersers such as the Helmeted Hornbill, to megaherbivores such as the Black Rhino, to migratory predators such as large sharks,” says Rob Cooke of the UK Centre of Ecology and Hydrology.
How can humans continue to hunt and fish without endangering species and their roles in ecosystems? The research team recognizes that subsistence hunters and fishers can have more sustainable long-term relationships with the animals they use, which can help us to reimagine our relationship with animals. But many more aggressive, industrial forms of use, such as industrialized fishing and unregulated capture of pets from the wild, are still dominant and require urgent attention from policymakers to limit their negative impacts.
Attending to this urgency, this research identifies species that are not only overexploited but also have outsized ecological influence globally. These species can be prioritized in conservation action plans that consider not only specific species but also the broader ecosystem-level implications of species loss.
Citation
Darimont, C.T., Cooke, R., Bourbonnais, M.L. et al. Humanity’s diverse predatory niche and its ecological consequences. Commun Biol 6, 609 (2023). https://doi.org/10.1038/s42003-023-04940-w
Abstract
Although humans have long been predators with enduring nutritive and cultural relationships with their prey, seldom have conservation ecologists considered the divergent predatory behavior of contemporary, industrialized humans. Recognizing that the number, strength and diversity of predator-prey relationships can profoundly influence biodiversity, here we analyze humanity’s modern day predatory interactions with vertebrates and estimate their ecological consequences. Analysing IUCN ‘use and trade’ data for ~47,000 species, we show that fishers, hunters and other animal collectors prey on more than a third (~15,000 species) of Earth’s vertebrates. Assessed over equivalent ranges, humans exploit up to 300 times more species than comparable non-human predators. Exploitation for the pet trade, medicine, and other uses now affects almost as many species as those targeted for food consumption, and almost 40% of exploited species are threatened by human use. Trait space analyses show that birds and mammals threatened by exploitation occupy a disproportionally large and unique region of ecological trait space, now at risk of loss. These patterns suggest far more species are subject to human-imposed ecological (e.g., landscapes of fear) and evolutionary (e.g., harvest selection) processes than previously considered. Moreover, continued overexploitation will likely bear profound consequences for biodiversity and ecosystem function.
Select figures
Figure 1. Use of vertebrates by humans and other predators
Figure 2. Diversity of uses by human predators
Figure 3. Spatial patterns of vertebrate use by human predators
Authors and affiliations
Chris T. Darimont1,2* Rob Cooke3*, Mathieu L. Bourbonnais4, Heather M. Bryan2,5, Stephanie M. Carlson6, James A. Estes7, Mauro Galetti8,9, Taal Levi10, Jessica L. Maclean1,2, Iain McKechnie11,12, Paul C. Paquet1,2, Boris Worm13,14r
1Department of Geography, University of Victoria, 2Raincoast Conservation Foundation3, UK Centre for Ecology & Hydrology, 4Department of Earth, Environmental, and Geographic Sciences, University of British Columbia Okanagan, 5Department of Ecosystem Science and Management, University of Northern British Columbia, 6Department of Environmental Science, Policy, and Management, University of California, Berkeley, 7Department of Ecology and Evolutionary Biology, University of California; Santa Cruz,8 São Paulo State University (UNESP), Department of Biodiversity, Rio Claro, SP, Brazil, 9 Kimberly Green Latin American and Caribbean Center, Florida International University (FIU),10Department of Fisheries, Wildlife, and Conservation Sciences, Oregon State University,11Department of Anthropology, University of Victoria,12Hakai Institute,13Department of Biology, Dalhousie University,14Ocean Frontier Institute, Dalhousie University
*= these authors contributed equally.
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