Human voices cause considerably more fear in wild mammals than the sound of lions, a study in South Africa has found.
Scientists played recordings of people talking normally through speakers hidden at water holes in the Kruger National Park.
About 95% of animals were extremely frightened and quickly ran away.
In contrast, recordings of snarling and growling lions elicited significantly less alarm.
The human speech they chose to play included local languages commonly spoken in the country.
Some elephants, in response to the big cat calls, even attempted to confront the source of the sound.
The study’s findings suggest that the animals, which included antelopes, elephants, giraffes, leopards and warthogs, have learnt that contact with humans is extremely dangerous, due to hunting, gun use and the use of dogs to catch them.
The fear exhibited goes beyond the Kruger National Park, showing a global pattern where wildlife tend to fear humans more than any other predator, according to the study.
The authors note that this poses a challenge for areas which rely on wildlife tourism, because the human visitors they want to attract are inadvertently scaring off the animals they have come to see.
But the findings also open up the potential to protect vulnerable species in these ecosystems. Human sounds, when used appropriately, could help protect against illegal poaching.