![]() ![]() Hopkin: Liana finds these reactions to unexceptional human utterances utterly remarkable. And so what did they do instead? They leave. Elephants realize that humans are a predator, but they cannot defend themselves against it. Zanette: So elephants recognize that lions are a predator, but they can defend themselves against that predator. Hopkin: They never respond that way to the sound of people. But it’s still going, so you can hear the elephants trumpeting as they eventually move away. Zanette: My favorite is still that one where it’s at night, and the elephants get so angry that a lion is there that they smash the camera, and the camera goes black. But in several videos recorded for the study, they actually move toward the source of the sound. Hopkin: Now, elephants did move when they heard lions growling. Hopkin: Drops his dinner and doesn’t look back after hearing the terrifying sound of. In another video, a leopard that’s dragging home a large order of impala. Hopkin: That’s the pitter-patter of rhinos heading for the hills from a video recorded for the study. Hopkin: But once they get going, they go. They have that big head, and they got to turn their head, their head and their huge bodies, and, you know, hightail it out of there. Zanette: It takes them a while to get their bulk going. Hopkin: And they’re history, whereas southern white rhinos. Zanette: Like, you know, giraffes, they take a little bit of time to get moving because they’re frigging huge, compared to a warthog, you know, which is gone right away. Hopkin: Some animals took longer than others to dash. Zanette: The leopards fled humans, not lions hyenas fled humans, not lions. Hopkin: They also leave the waterhole 40 percent faster when they hear humans. Zanette: Animals are two times more likely to flee when they hear humans than when they hear lions. Hopking: To serve as a nonpetrifying control. When an animal would wander within about 30 feet of the device, a sound clip would play from the speaker while the video camera recorded the creature’s response. Hopkin: The researchers set up motion-sensitive camera-and-speaker systems at 21 water holes around Greater Kruger National Park. Hopkin: On the savanna, Liana and her team looked to the local animal population to determine “Who’s more menacing, them.? So if animals are gonna be maximally afraid of what we consider to be the most fearsome, large carnivore predator on the planet, it’s going to be there. Zanette: Because it’s home to the largest population of the most fearsome predator on the planet, the king of beasts: lions. Hopkin: But can we possibly be as intimidating as creatures we typically think of as predators such as lions and tigers and bears? To find out, Liana and her colleagues headed to South Africa. Zanette: We know now that, through global surveys, that humans kill prey at far greater rates than other predators do. Hopkin: So where do people fit in? Animals certainly have good reason to fear us. ![]() That’s the ecological consequences of fear. And we’ve shown in those other studies that that can affect population numbers and lead to cascading effects down the food chain. Hopkin: In previous studies-on everything from cougars and sparrows to European badgers-Zanette found that fear affects animals’ fitness. Zanette: But we can see, too, that there’s going to be the cost, right? There’s going to be trade-offs. Hopkin: That includes skedaddling like your life depends on it-because it does. We all mount behavioral antipredator defenses to avoid being killed. Zanette: All animals, even the human kind, have evolved as prey for something else, right? And so we all have the same responses when we encounter a life-threatening event. Zanette: When, for example, I’m out in South Africa, and I hear lions snarling and growling, I run, y’know? I’m not hanging around. Hopkin: Even if you’re a professor of biology. Zanette: You hear a predator around, you take off. Hopkin: But even if a predator doesn’t kill you, it can still scare the pants off you, which then affects your behavior. Zanette: When we think about how predators can affect prey populations, we think about killing, right? Like the lion goes in and kills the zebra, and that's one less zebra in the population. She says that fear is an overlooked aspect of predator-prey interactions. ![]() Hopkin: Liana Zanette is a professor of biology at Western University in Ontario. Liana Zanette: We’ve been working in the ecology of fear for a couple of decades now. Hopkin: The work appears in the journal Current Biology. Hopkin: A new study shows that animals from impalas to elephants are more likely to flee from a talking human … Hopkin: Well, if you’re a mammal in the African savanna, it may well be this: What’s the scariest sound you can think of? Is it…? Karen Hopkin: This is Scientific American’s Science, Quickly. ![]()
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