Some elephant communications might be felt as well as heard, report UC Davis researchers, who for the first time have recorded below-ground energy waves when elephants vocalize with low-frequency rumbles and when they stomp their feet during a mock charge. "We found that there is a measurable amount of energy propagated in the ground when an elephant vocalizes with low- frequency rumbles," says doctoral candidate Caitlin O'Connell, who conducted the study with animal behaviorist Lynette Hart, director of the UC Davis Center for Animals in Society, and geophysicist Byron Arnason of Tezar Inc. of Austin, Texas. While seismic communications have previously been identified in crabs, insects, spiders, amphibians, lizards, snakes, alligators and small rodents; the elephant seal is the only other large mammal known to produce such vocalizations. At a private elephant-training center in Texas, O'Connell, Arnason and Hart used microphones and geophones to confirm that the elephants were transmitting signals directly through the ground and air. The researchers estimate that ground signals can be detected from the elephant rumbles for nearly 5 miles and from the stomps for more than 30 miles. If detectable by elephants, such seismic signals could help them avoid approaching danger, sense distant thunder storms and even find a mate. O'Connell presented their findings at the recent meeting of the Acoustical Society of America in San Diego.