By Victoria Gill
Science and nature reporter, BBC News
A group of elephants with an older matriarch reacts to roars of male lions
Elephants pay close attention to their elders, especially when they hear the sound of an approaching predator, scientists have found.
A research team monitored African elephants' reactions when they heard the sound of lions roaring.
Groups of animals with older female leaders, or matriarchs, very quickly organised themselves into a defensive "bunch" when they heard a male lion.
The findings are reported in the Royal Society journal Proceedings B.
Female elephants live in organised social groups
The researchers already knew that older female elephants played very important roles in their social groups.
But in this study, led by Karen McComb and Graeme Shannon from the University of Sussex, UK, scientists managed to put this to the test in a natural setting.
The researchers first recorded lion roars, and separated their recordings into roars from male lions and those from female lions. They then used loudspeakers to play these sounds to 39 groups of female elephants in Amboseli National Park in Kenya.
The groups with the oldest female leaders, or matriarchs, responded very quickly - and very appropriately - to the roars of male lions. The animals stopped to listen attentively, then bunched together to defend themselves.
"Male lions present a very real threat [for elephants]," said Dr McComb. "They can be successful in bringing down a calf even when alone."
Female lions, however, are unlikely to attack an elephant unless they are in large groups, and the researchers found that older female elephants were able to distinguish the sound of a male lion from a female.
Male lions occasionally hunt young elephants
The older females' groups were much more likely to form this defensive bunch and even to aggressively approach the loudspeaker when they were played the roars of male lions.
"Younger matriarchs didn't seem as bothered by male lions as they should have been," Dr McComb said.
"We think its because they hadn't had sufficient exposure to that threat; lions don't [attack elephants] that often."
She and her colleagues are now hoping to find out what exactly these experienced females do to trigger this co-ordinated response.
"There are no loud vocal cues," she said. "We think they're quite subtle postural cues and we're also looking for soft vocalisations."
Age and experience
Older individuals clearly have a vital role in how well elephants function in their social groups
The team had found, in previous research, that these older - apparently wiser - matriarchs were better able to tell if other elephants were "friends" or intruders into their social groups.
Josh Plotnik from the University of Cambridge, who has studied complex social behaviour in Asian elephants, said the results were "very exciting" and had implications for future studies of a variety of social species.
"My experience with Asian elephants suggests a similar trend," he told BBC News. "Older females seem much more attuned to potential threats than younger females, which is most likely due to greater experience with a greater variety of environmental pressures."
Dr McComb said she was surprised by the elephants' ability quickly and accurately to tell the difference between male and female lion roars.
"The differences are very subtle," she said. "It's very difficult for us to tell them apart."
She added that the study had demonstrated the need to conserve and protect these older animals.
"These older individuals clearly have a vital role in how well elephants function in their social groups," she said. "This will have a wider effect on their longevity and reproductive success."