UC Santa Cruz study reveals mountain lions fear human voices

A study led by a graduate student in environment studies at UC Santa Cruz finds mountain lions flee when they hear human voices.

“We exposed pumas in the Santa Cruz mountains to the sound of human voices to see if they would react with fear and flee, and the results were striking. They were definitely afraid of humans,” said Justine Smith, lead author of the paper “Fear of the human ‘super predator’ reduces feeding time in large carnivores.” It was published Wednesday in an online edition of the Proceedings of the Royal Society B.

New research into the behavior of these big cats indicates that they don’t like encountering humans any more than we like bumping into them on hiking trails. Researchers said the findings are valuable as human development encroaches on lion habitat and drives up the number of human-puma encounters.

“We exposed pumas in the Santa Cruz mountains to the sound of human voices to see if they would react with fear and flee, and the results were striking: They were definitely afraid of humans,” said Justine Smith, lead author of the paper “Fear of the human ‘super predator’ reduces feeding time in large carnivores,” published in the June 21 online edition of the Proceedings of the Royal Society B.

Smith’s team placed audio equipment at puma kill sites in the Santa Cruz Mountains; when a puma came to eat, its movements set off motion-activated technology that broadcast recordings of people talking, and a hidden camera captured the puma’s reaction.

“We found that pumas almost always ran from the sound of humans-and almost never ran from the sound of frogs,” said Smith, now a postdoctoral researcher at UC Berkeley. In 29 experiments involving 17 pumas, the pumas fled in 83 percent of cases as soon as it heard human voices, and only once upon hearing frogs.

The study also found that pumas have changed their eating behaviors which could reflect their well-being in human dominated areas.

“We found that pumas took longer to return to their kills after hearing people, and subsequently reduced their feeding on kills by about half,” said Smith. “Those behavioral changes are significant, as our previous work has shown that they cause pumas to increase their kill rates by 36 percent in areas with high human activity.”

UC Santa Cruz researchers said this was the first study that links the fear of humans to feeding behavior in large carnivores, said Chris Wilmers, associate professor of environmental studies at UCSC.

“Fear is the mechanism behind an ecological cascade that goes from humans to pumas to increased puma predation on deer,” said Wilmers, a wildlife ecologist who studies the cascading effects large carnivores can have on their prey. “We’re seeing that human disturbance-beyond hunting-may alter the ecological role of large carnivores. As we encroach on lion habitat, our presence will likely affect the link between top predators and their prey.”