Contrary to popular myth, waving a red rag may leave a bull unmoved. But it could end in tears for anyone foolish enough to try it with a bull elephant, scientists have found.

Although they are colour-blind, displaying red garments in front of elephants in Kenya enrages them because they associate red fabric, which they see as a drab hue, with the clothing worn by a tribe who throw spears at them as a test of manhood.

It is bulls that traditionally have the reputation of flaring up when red capes are waved at them in bullrings, where they are surrounded by screaming spectators while being prodded into action. In reality, the colour of the capes is irrelevant to the bulls, whereas elephants have learnt to associate red with danger.

The reaction to red clothing was established when researchers investigated reports that elephants acted more aggressively towards the Masai tribe – whose young male warriors wear red – and their cattle than to other tribes. Even more striking than the reaction to colour was the finding that the animals were able to tell the difference between a friendly and a dangerous human by sniffing them.

Their sense of smell is so acute that they can distinguish rapidly between the scent of a Masai warrior and that of the crop-growing Kamba tribe, who both live in Kenya.

“We think that this is the first time that it has been experimentally shown that any animal can categorise a single species of potential predator into subclasses based on such subtle cues,” said Lucy Bates, of the University of St Andrews.

Researchers studying the elephants conducted experiments in which red and white fabrics, some of them clean and unused and others worn by Masai or Kamba people, were placed near to the elephants. The animals, from 18 family groups living in the Amboseli ecosystem in Kenya, were able to detect the scent of worn clothes from 100 metres or more, pointing their trunks at the spot to sniff them.

Any clothing that smelt of the Masai caused them to react with fear and nervousness. They ran farther away and faster than when they smelt garments worn by the Kamba.

“With any scent present, fear and escape reactions seem to dominate anything else,” Dr Bates said.

They were much happier in the vicinity of clothing smelling of the Kamba people but when the elephants came across clean red fabric they became aggressive, stamping their feet, putting their heads down and their trunks up.

Scientists involved in the study said that it was clear that the elephants were able to distinguish between the Masai and Kamba tribes.

They suspected that the agressive reaction when coming across unworn red fabric indicated that the animals associated it with the Masai but that their sense of smell told them there were no spearmen nearby.

“Whereas elephants had reacted with fear to the scent of Masai-worn clothes, in this visual case their reaction was to threaten,” the researchers reported in the journal Current Biology. Dr Bates and Richard Byrne, also from the University of St Andrews, used research from the Amboseli Elephant Research Project in Kenya for the study.

“Different human ethnic groups present varying risks to elephants and we have shown that the elephants of Amboseli National Park do classify and respond to these ethnic groups differently,” the researchers added.

Professor Byrne said: “We see this experiment as just a start to investigating precisely how elephants see the world, but it may be that their abilities will turn out to equal or exceed those of our closer relatives, the monkeys and apes.”

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