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Raccoon study measures ecological impact of fear

"One of the major consequences is that when you take away the large carnivores, you get outbreaks of the species that they eat," explained researcher Jason Suraci.
By Brooks Hays   |   Feb. 26, 2016 at 4:04 PM

VANCOUVER, British Columbia, Feb. 26 (UPI) -- With wolves, bears and cougars gone from British Columbia's Gulf Islands, raccoons have proliferated. Their outsized presence has wreaked havoc on the island ecosystems, their appetite proving especially detrimental to fish, crustaceans and song birds.

In an effort to remedy the problem, researchers at the University of Victoria tested the effects of barking sounds on raccoon behavior. Dogs are the only raccoon predators that remain on the island.

Scientists hypothesized that the fear instilled in raccoons by the sounds of barking dogs might deter their rates of consumption and reproduction, and they were right.

Raccoon populations subjected to sounds of barking dogs spent 66 percent less time foraging, leading to a 61 percent increase red rock crabs and an 81 percent increase in tidal fish populations.

The study, published in the journal Nature Communications, is proof of the ecological power of fear.

"Humans have done an excellent job of wiping out large carnivores across the globe and we're only starting to understand what the ecological consequences of that are," Jason Suraci, a PhD candidate in biology, explained in a press release. "One of the major consequences is that when you take away the large carnivores, you get outbreaks of the species that they eat -- herbivores like deer and smaller predators like raccoons."

"What we've shown is that we have to consider the behavioral interactions top predators have with their prey and not just the actual predation -- the killing and consumption -- when we're thinking about how to restore ecosystems from which large carnivores have been lost," Suraci concluded.

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