Fear could be utilized by environmentalists looking to balance delicate ecosystems, according to a new study. This new research could lead to new means of managing wild areas.
Raccoons living on the Gulf Islands in British Columbia have little reason to experience fear in the wild. Large predators, including wolves and cougars, were eliminated from the islands nearly 100 years ago. Now, the animals are wreaking havoc on songbird populations, as well as some fish and intertidal crabs.
These animals were exposed to sounds of natural predators, including wild dogs, designed to elicit fear. These recordings, as well as non-threatening sounds such as those made by seals, were played in the raccoon's habitat. Investigators found the sounds of predators reduced the amount of foraging carried out by the medium-sized mammals. The calls of wild dogs reduced foraging times of raccoons by 66 percent below seal sounds.
Predators in the wild elicit fear in prey, and these effects appear to ripple down to smaller animals, serving to conserve the ecosystem, researchers determined.
"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," said Liana Zanette of the University of Western Ontario.
Researchers have argued before that fear of predators reduces the amount of plant life eaten by the animals. This new study positively shows that "fear itself" can help reduce the damage done to ecosystems by herbivores and other prey animals.
Once the behavior of one species of top predator is affected, the effects cascade down to other forms of life in a given ecosystem, investigators determined. After the reintroduction of wolves to Yellowstone Park, foraging by elk was reduced, resulting in increased populations of plants and songbirds.
A similar effect had been noted before in groups of insects, as grasshoppers altered their daily patterns when frightened by a spider, even if the predator was unable to attack its prey. Researchers questioned, however, if similar behavior took place among larger species of animals.
Farmers, ranchers and other people living near wild areas can be apprehensive about the reintroduction of top predators, such as wolves, into once-natural habitats.
Study of how fear of predators could assist in preserving ecosystems was published in the journal Nature Communications.
