- Most natural predators prefer juvenile prey, but humans preferentially target adult prey, recent study has found.
- Such disproportionate killing of adult prey can affect the reproductive potential of populations in the wild, and ecological interactions within food webs, authors write in the paper.
- Humans most likely do not provide any ecosystem services in return, researchers say.
We hunt for food, and we hunt for fun. But we are unlike other natural predators, according to a study recently published in Science. We are “super-predators”, researchers say.
Most natural predators on land — like lions, bears and tigers — prefer to hunt juvenile prey animals for food. But on analyzing a global database of over 300 studies, researchers found that humans kill 14 times more adult prey than other predators. Humans also hunt carnivores at nine-times the rate of other predators, they found.
“We kill those carnivores not for food, but for trophies and — sometimes — to eliminate them as competitors,” Chris Darimont, lead author of the study from the University of Victoria, told Science news. “Because they naturally don’t face much predation, they have not evolved ways to successfully avoid humans or reproduce fast enough to make up for human-induced losses.”
Moreover, the formerly dangerous act of searching for, pursuing and capturing large-sized prey is now easier due to advanced killing technology, authors write in the paper.
“Hunters ‘capture’ mammals with bullets, and fishes with hooks and nets. They assume minimal risk compared with non-human predators, especially terrestrial carnivores, which are often injured while living what amounts to a dangerous lifestyle,” Darimont told reporters, according to the BBC.
Humans hunt a disproportionately large proportion of adult prey in oceans too, compared to other marine predators, the study found.
The consequences of targeting adult prey, however, can be catastrophic. It can affect the reproductive potential of populations in the wild, and ecological interactions within food webs, the researchers warn in the paper.
Conservation biologist Boris worm from Dalhousie University in Nova Scotia, Canada, compares adult individuals with financial capital in a bank account, and juveniles to the interest generated. “Depleting the capital is risky, particularly in long-lived, late-maturing organisms,” he writes in a commentary in Science. “Trophy hunters and fishers, in particular, often target the largest, healthiest, and fittest organisms.”
So not only does the human way of hunting seem thoughtless, humans most likely do not provide any ecosystem services in return, the authors write, such as disease or wildlife regulation.
“The disparity between human and animal predation rates is a useful way of illustrating how ecologically out-of-whack many exploitation rates and management policies are,” Nicholas Dulvy from Simon Fraser University in Burnaby, Canada, told Science news.
- Darimont CT, Fox CH, Bryan HM, and Reimchen TE (2015) The unique ecology of human predators. Science 21: 858-860.