Video: Flight reactions of various African animals when listening to human speech. © Current Biology, Zanette et al.
The real “king” of the predators is humans: African wild animals fear the human super-predator more than lions, according to an experimental study. Human voices trigger much more intense escape reactions in a wide range of animal species than the sounds of big cats. The apparently deep-rooted fear of humans also has an impact on animal protection and tourism, say the scientists.
The large predators form the top of the food chains in terrestrial ecosystems. The lions play an almost symbolic role. The “majestic” cats are the largest predators in Africa and because they hunt in packs, they also develop particularly powerful fighting power. This can even pose a threat to large and defensive animal species. This is why many wild animals respond to the signs of the presence of lions with defensive or flight behavior. But in Africa and around the world there is also another more dangerous predator: In many ecosystems, humans kill more wild animals than the top animal predators, studies show. It has already been shown that many animal species show particularly intense fear behavior when they sense the proximity of people.
Man versus lion
Against this background, an international team of researchers has now investigated for the first time the question of who appears more frightening in Africa – humans or the “king of the animals”. The scientists carried out acoustic experiments in the Greater Kruger National Park (GKNP) in South Africa, where there is still a particularly large lion population. In their experiments, they focused on water sources in the dry season. These are not just typical hunting places for big cats. Although the GKNP offers a comparatively high level of protection, poachers can sometimes lie in wait for animal visitors there.
For their study, the scientists installed camouflaged loudspeakers at some waterholes through which they could play various acoustic stimuli to the wild animals. In addition to other test and control sounds, these included recordings of human voices in the various languages spoken in the region. Typical lion sounds were used for comparison. “It was growling and hissing – not roaring. This meant that the lions’ vocalizations were comparable to those of speaking humans,” explains co-author Clinchy from Western University in London, Canada. The animals’ reactions to all test sounds were recorded by video cameras for later evaluation.
Fear of humans shapes the savanna wildlife
As the team reports, the analyzes of the total of 15,000 videos initially fundamentally confirmed how many animals reacted to the lion noises with fear and flight. The sounds of gunshots or dogs barking, which can be associated with human threats, also had a similar deterrent effect. But by far the strongest effect was the direct human signal: the startle effect of voices appears to be about twice as intense as that of the other test noises and the lion sounds. Accordingly, almost all of the 19 species fled from the watering holes more often or more quickly due to this acoustic stimulus than in the case of the lion sounds. The range ranged from elephants, rhinos, giraffes and antelope species to warthogs.
Since humans have long hunted these animals for their meat, for certain products or for trophies, they have apparently adapted accordingly. “The fear of people seems to be deeply rooted and omnipresent,” says Clinchy, summing up the result. As the team reports, the elephants’ special reactions seemed particularly interesting. As it turned out, when lions heard noises, they generally didn’t leave the waterholes, but rather just moved closer together. This seems plausible, because the big cats can normally only pose a threat to the young of the defensive giants. But at the sound of human voices, the animals did not move together but retreated. As is well known, they have no way of countering the weapons of people lurking at waterholes and that is why they flee.
“Our results expand the evidence that wildlife worldwide fear the human super-predator far more than other predators,” the team writes. In addition, this effect is becoming increasingly important for species protection – because fear can have harmful effects. “The proven great fear of humans can have significant ecological consequences and thus poses challenges for tourism in Africa,” say the authors. On the other hand, according to them, the effect could also be used for protection: the team is now investigating the extent to which human noises could specifically keep endangered species such as the southern white rhinoceros away from known poaching areas in South Africa.
Source: Cell Press, specialist article: Current Biology, doi: 10.1016/j.cub.2023.08.089