There is one predator that scares both bears and mountain lions

Bears and mountain lions may rank among North America’s most feared predators, but they appear to fear one animal more than people fear them: humans.

Two studies examined how the animals respond when people approach. Their findings suggest that bears and mountain lions do not simply react to human presence. They actively change their behavior to stay away whenever they can.

One study, led by U.S. Forest Service wildlife biologist Philip Manlick, tracked black and brown bears feeding along salmon streams in southeastern Alaska. Motion-activated speakers played seagull calls, vehicle sounds or human voices as bears approached, while cameras recorded their reactions.

The bears were twice as likely to retreat quickly after hearing vehicle sounds than after hearing seagulls. They were nearly 10 times more likely to flee when they heard human voices. Yale ecologist Oswald Schmitz linked the bear and mountain lion studies in a review published in Current Biology, writing that the findings change how human-carnivore conflict is discussed.

The numbers also put the danger in perspective. Grizzlies attack about 11.4 people a year on average, while mountain lions attack four to six. Only 63 human deaths from black bear attacks were recorded between 1900 and 2009. By comparison, lightning strikes about 580 people each year in the United States and Canada. The bear research also points to a wider ecological effect, because bears carry salmon into nearby forests, leaving remains that decompose and fertilize the ecosystem.

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These findings change how human-carnivore conflict is discussed.