Animals on the African savanna are more scared of human voices than the roaring of lions. Researchers have shown that almost all species, including elephants and warthogs, run faster and farther when they hear voices compared to when they hear the apex predator. This study focuses on the effects of the presence of humans on animal behavior, specifically the ecology of fear.
The lion is the largest predator in Africa. Its presence alone influences the behavior of other animals. However, humans have been hunting other creatures on a massive scale for thousands of years, making them super predators. According to a 2015 study, the rate of human predation is estimated to be 10 times higher than that of large carnivores. To examine the response of animals in South Africa’s Greater Kruger National Park to these threats, a team of ecologists deployed cameras and speakers near water sources. The speakers played recordings of human conversations, lion growls, hunting dogs and gunshots. Birdsongs were used as the control mechanism. All sounds were played at the same volume of 60 decibels.
The findings of the study published in Current Biology are clear. After analyzing over 15,000 videos, the research team found that animals are twice as likely to run away when they hear humans compared to hearing lion or hunting sounds. This pattern was observed in 18 out of the 19 species that approached the waterholes. Giraffes, leopards, hyenas, zebras, kudus, wild boars, impalas — all of them tend to flee more from the sound of a person’s voice than from the growls of lions. The only exception was the African wild dog, which showed a higher tendency to flee from lions. “This makes sense as lions target African wild dogs. However, we cannot be certain about the reliability of these patterns because the statistical significance is limited due to the scarcity of African wild dog videos,” said team leader Liana Y. Zanette (University of Western Ontario, Canada). There were only 13 videos of African wild dogs compared to hundreds of videos of other species.
The researchers also measured how quickly the animals fled when they heard humans compared to when they heard lions, and found that they ran away 40% faster. Again, the fear of humans was greater than the fear of lions and gunshots. Even the largest animals in the savanna — elephants and rhinos — ran away faster. In contrast, elephants would often furiously destroy the speakers when they heard a lion, a behavior that was never observed when they heard a human voice.
To understand the relevance of these results, it’s important to consider two things. First, this large park was one of the first to ban hunting several decades ago, although poaching is still a problem. This implies that the fear of human hunters should have diminished by now. Second, the Greater Kruger National Park has a large lion population and serves as a breeding ground for reintroducing them to areas with depleted populations. While further research is needed in other parts of Africa, several studies have shown that various wildlife species, such as badgers in the U.K., white-tailed deer in the U.S., and wallabies in Australia tend to avoid humans more than their natural predators. Zanette says this growing body of evidence supports the premise that animals everywhere fear humans more than any other predator on the planet.
Zanette has conducted extensive research in animal biology, specifically focusing on the ecology of fear. This innate fear, once shared by the humans who lived long ago, continues to profoundly influence the dynamics of life. Showing how animals abandon a life-giving water source in the arid savanna highlights the profound influence of fear on their behavior. Predators curb wildlife populations by killing, but the stress they can cause in their prey can lead to reduced population growth. “Our previous research has also demonstrated that fear can have a cascading effect with impacts throughout the entire food chain,” said Zanette.
“Fear can have a cascading effect with impacts throughout the entire food chain.”Liana Y. Zanette, University of Western Ontario, Canada
The study identified another alarming human impact. “If wildlife do not differentiate between humans engaged in benign or lethal activities, e.g., photographic tourism vs. hunting, then the very considerable ecological impacts now demonstrated to be caused by the fear of humans can be expected to result from exposure to even benign humans.” Commenting on this finding, co-author Michael Clinchy said, “Many believe animals lose their fear of humans if not hunted, but our research shows this isn’t true. Fear of humans is deeply ingrained and widespread, so it’s crucial to consider this in conservation efforts.”
If humans significantly impact the environment just by being present, it may be tempting to prohibit or limit human-animal interaction for conservation. However, Zanette warns about the dangers of this radical approach. “When parks are funded by taxpayers, as in Europe and North America, it is indeed possible to close large sections. This approach, however, is not feasible in Africa since no visitors means no revenue, and it leaves the park vulnerable to poachers… The worst thing that can happen to Africa’s parks and protected areas is for tourists to stop going, so encourage your readers and others to visit them.”
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