The terrifying sound of a human voice

By | July 17, 2019

Ed Yong writes:

In the summer of 2017, the mountain lions, bobcats, and other residents of the Santa Cruz Mountains were treated to the dulcet tones of the ecologist Justin Suraci and his friends, reading poetry. Some of the animals became jittery. Others stopped eating. A few fled in fear.

Suraci, who’s based at the University of California at Santa Cruz, wasn’t there to see their reactions. He and his colleagues had strung up a set of speakers that would regularly play recordings of human speech in an area where people seldom venture. And they found that, the quality of the poetry aside, even the gentlest of human speech can make wild animals—even top predators—unnerved and watchful, in ways that shake entire food webs. It’s the clearest demonstration yet that we are among the scariest of animals—a super-predator that terrifies even the carnivores that themselves incite terror.

Even when predators aren’t killing anything, their tracks, smells, and sounds can instill a state of simmering unease in their prey. This creates what ecologists call a “landscape of fear”—a mental map of risk that affects how hunted animals move over physical terrain. For example, in 2016, Suraci and his adviser, Liana Zanette, from Ontario’s Western University, showed that raccoons in the Gulf Islands spent less time foraging on local beaches if they heard recordings of dogs. And because the raccoons skedaddled, the rock pools filled with more fish, worms, and crabs. Fear reshaped the entire beach. [Continue reading…]

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