When African elephants stomp and trumpet as a predator approaches, other distant elephants can get the news by feeling the ground rumble, a team of scientists recently confirmed.
The vocalizations and foot stomps resonate at a frequency that elephants can detect in the ground, according to Caitlin O'Connell-Rodwell, a biologist at Stanford University in Palo Alto, California.
She and her colleagues played the ground-shaking component of these vocalizations to elephants gathered around a watering hole in Etosha National Park in Namibia (map).
"What we saw was they bunch into a tighter group, orient in the direction of where the signal is coming from, and then leave the area much sooner than they would if nothing was played," O'Connell-Rodwell said.
These behaviors are indications that the elephants detected the call and interpreted it as a warning, she added.
O'Connell-Rodwell and her colleagues reported the finding this month in the online edition of the journal Behavioral Ecology and Sociobiology.
O'Connell-Rodwell first theorized that elephants use vibrations to communicate in 1992, but this is the first scientific evidence to support her theory. (Read "Elephants May 'Talk' Via Vibrations")
Peter Narins, a biologist at the University of California, Los Angeles, says he's pleased to see her theory validated by a scientific study.
"She's shown it before, but this is real. The data are here, the controls are here, and it's been collected in a study," he said.
Now O'Connell-Rodwell and colleagues are preparing a follow-up report on whether the elephants can distinguish different types of calls.
Preliminary results suggest that elephants react most vigilantly to familiar warning calls, but they also crowd together and act nervous when they detect unfamiliar calls.
Vibration Threshold
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