Although it may seem like an unlikely scenario, scientists from the University of Western Ontario say that the fear that large carnivores strike into their prey can have cascading effects down the food chain that can actually maintain the health of ecosystems, highlighting the importance of large carnivore conservation.
The team experimentally demonstrated that fear of large carnivores is a powerful enough factor to make its way down the entire food chain and that restoring this fear in struggling ecosystems can reverse the negative impacts that stem from the loss of large carnivores currently seen in the Earth's ecosystems.
"These results have critically important implications for conservation, wildlife management and public policy," Liana Zanette, who participated in the research, said in a press release. "We have now experimentally verified that, by instilling fear, the very existence of large carnivores on the landscape - in and of itself - provides an essential 'ecosystem service,' and failing to consider fear risks dramatically underestimates the role large carnivores play in structuring ecosystems."
Despite the importance of large carnivores for ecosystem health, humans fear them due to the threats that they pose to human life, which is one reason why conservation actions such as the reintroduction of carnivores into ecosystems are so controversial.
In the past, many have argued that the presence of carnivores creates a "landscape of fear," which is necessary to keep their prey from eating too much, but the new study expands on this much further and provides definitive evidence of their importance.
The team was able to experimentally manipulate fear by playing threatening sounds of large carnivores from speakers along the shoreline of British Columbia's Gulf Islands, where songbirds and intertidal crabs and fish are currently being devastated by raccoons, who have no predators in the area. After playing these sounds for months at a time, the fear created by the sounds decreased the time that raccoons spent feeding and reversed their impacts on their prey, an effect that cascaded through the entire ecosystem.
The findings were published in the Feb. 23 issue of Nature Communications.
