Science
Now Daily News
May 31, 2007
By Betsy Mason
Original
Article
 Elephants know the difference between
good vibrations and bad, according to new research
into the big animals' low, rumbling alarm calls.
They pay attention to seismic waves made by elephants
they know and ignore those of strangers.
Can you hear me now?
An elephant puts its trunk to the ground
to detect
ground vibrations made by other elephants.
Credit:
C. O'Connell-Rodwell
Behavioral ecologist Caitlin O'Connell-Rodwell
of Stanford University in Palo Alto, California,
discovered in 2004 that African elephants
communicate with each other from kilometers away
through ground vibrations. Although they make
the calls with their trunks, the sounds also
travel several kilometers along the surface of
the ground, about as far as airborne sounds.
O'Connell-Rodwell witnessed groups of Namibian
elephants stopping in their tracks, leaning forward
onto their toes, and pressing their trunks to
the ground. The animals often adopted this listening
posture before the arrival of another group of
elephants. O'Connell-Rodwell recorded various
elephant calls and found that wild elephants
responded to ground vibrations alone. Researchers
aren't sure how elephants detect the waves, but
they have vibration-sensitive cells in their
feet and trunks.
In the new study, O'Connell-Rodwell asked whether
the elephants can tell who is making the alarm
calls. So the team recorded alarm calls made
by elephants encountering lions in Kenya and
Namibia. Then they converted the sounds into
seismic waves and played them back to Namibian
elephants visiting a water hole. The elephants
responded to the Namibian vibrations by freezing,
huddling, and leaving the area sooner. The elephants
appeared to detect the Kenyan calls--they sometimes
paused and looked more alert, for instance--but
did not react dramatically. The Namibian elephants
also ignored control recordings of synthesized
sounds that had similar frequency and duration.
The research is slated to appear in the August
Journal of the Acoustical Society of America.
The scientists don't know why elephants respond
differently to the alarm calls, but O'Connell-Rodwell
suspects it is not due to dialect differences.
The calls from the two countries are similar
in frequency and duration. More likely, she says,
is that the elephants trust the calls from animals
they know but not those of strangers.
Behavioral ecologist Jan Randall of San Francisco
State University in California, who studies kangaroo
rats that use foot drumming vibrations to communicate,
agrees that the elephants may be gauging the
trustworthiness of the calls and heeding only
the ones from reliable sources. That might help
them avoid expending unnecessary energy responding
to bogus calls. But alarm calls are hard to capture
in the wild, and the researchers need to test
more samples, Randall says. "It's an exciting
result and it's really suggestive, but it needs
some of the follow-up work to really pin it down."
Related site: Elephant
Listening Project
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