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.
During the experiment they noted that 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.