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Human voices scare African mammals more than lions
African wildlife is more than twice as likely to flee from the sound of humans than lions.
While the fear of human voices could pose issues for tourism in the region, it also provides new ways of keeping animals away from poaching hotspots.
What’s the scariest sound on the savannah? A conversation.
Though it might be a cliché to say that humans are the most dangerous animals of all, new research appears to support it. The vast majority of large African mammals, including giraffes, hyena and zebras, were more likely to flee from the sound of two humans talking than from the sounds of lions, gunfire or dogs.
Those that did run also ran about 40% faster from people than the noise of big cats, with elephants and rhinos particularly quick to flee.
The study, conducted in South Africa‘s Greater Kruger National Park, provides more evidence that humans are a unique ‘superpredator’, being able to target a wide variety of different prey all over the world at unprecedented and unsustainable levels.
Professor Liana Zanette, the study’s lead author, says, ‘We usually think about large carnivore predators being at the top of the food chain, but humans are also lethal predators, and ones with a unique ecology.’
‘The pervasiveness of the fear throughout the savannah mammal community is a real testament to the environmental impact that humans have. Our presence in that landscape is enough of a danger signal that these animals respond really strongly, way more than any other predator.’
The findings of the study were published in the journal Current Biology.
Humans as superpredators
The idea of humans as a superpredator comes from a 2015 paper, which compared our rate of hunting with other predators on land and sea. It found that our species hunted other terrestrial carnivores at a rate nine times higher than any other animal, and fish as much as 14 times more than any marine predator.
This research also revealed that humans hunt differently than any other predator. While most predators target weaker, often younger prey, humans tend to hunt large and healthy adults.
The sounds of people triggered stronger flight responses than lions, which could have implications for tourism. Image © Shutterstock/Ana Gram.
As large adults are the individuals most often responsible for breeding, this limits a species’ ability to maintain its population, pushing the animals into decline.
At the time of the original study, however, a lack of information made it hard to prove humanity’s status as a superpredator. But over time, new research has started to build up a bigger case that we are unique hunters.
One line of evidence looks at how animals react to humans compared with other predators. If prey are more afraid of humans than other hunters, by showing more or greater levels of anti-predator behaviours, it suggests that our form of predation is unique.
Dr Michael Clinchy, another co-author of the research, says, ‘Most mammals won’t die of disease or hunger, but instead by being eaten by a predator. The bigger the animal, the bigger the predator that finishes it off will need to be.’
‘As lions are the biggest group-hunting land predator on the planet, they should be the scariest to most prey. We decided to compare the fear of humans versus lions to find out if humans are scarier than the scariest non-human predator.’
How does the human voice affect wild animals?
To investigate the fear that humans inspire, the team planted speakers and cameras around 21 watering holes in the national park during the dry season between June and August. At this time of year, animals come to the watering holes to drink as other sources of water disappear.
This also makes it an attractive site for hunters, including humans and lions. The latter make use of watering holes to find prey, eating a wide range of animals from elephants weighing over a tonne to small rodents and reptiles.
Through the speakers, the team played a variety of recordings, including clips of people speaking calmly in four different languages spoken in the region, as well as lion vocalisations.
The sounds of gunshots and dogs were also played to simulate the sound of human hunting.
The flight responses were stronger for certain species, such as rhinos, which could be used to help protect them against poachers. Image © Shutterstock/Travel Stock.
The response of the animals was compared to a control recording of bird calls, to ensure that it wasn’t the presence of noise alone that was causing a reaction.
The sounds were also all played at the same volume, which could possibly influence the response of the animals to hunting noises. As dogs and gunshots are louder than humans in real life, this could have given the impression that they were further away, triggering a lower response in the wildlife.
In any case, while the study found that the sound of dogs and gunshots caused the mammals to run around three times more than the control, the sound of humans was the most significant. As a whole, the mammals were nine times more likely to run when they heard people chatting. But not all mammals responded in the same way.
While giraffes, leopards and warthog were more likely to abandon the watering hole when hearing humans rather than lions, elephants were less likely. It’s thought that this might relate to their dependence on water to support their large body size, making them more likely to stay put.
The results of the study add to growing evidence from other areas of the world that animals tend to react more strongly to humans than the top predator in their environment. Moose, for instance, abandon sites three quarters of the time when human voices are played, while mountain lions abandon their meals around 40% of the time after hearing humans.
If the presence of humans alone is enough to disturb local wildlife, this could pose a problem for safari tourism in Africa. Previous research suggests that anti-predator responses can cause animals to change their behaviour, or affect the number of offspring they have.
While certain areas of reserves could be declared off-limits to people to allow respite for affected animals, this will impact the funding of reserves which rely on tourists.
While bad for tourism, it could be good for conservation, as human voices could be used to keep animals away from poachers. For instance, rhinos abandoned waterholes much quicker when they heard human voices over other sounds, which could help to drive threatened species like the black rhino away from places where poachers are known to lie in wait.
If evidence for the superpredator continues to build, it suggests that our already strained relationship with the natural world is even more complex than we thought.
