June 20, 2005 — Elephants not only converse with each other, but each possesses its own unique, expressive voice, according to a new study on African elephants at Disney's Animal Kingdom in Florida.

The findings suggest elephants live rich social lives and feel an array of human-like emotions. The data also strengthen claims that animal communication can be content-rich and emotionally complex.

While careful human listeners might hear elephant conversations, elephants, particularly chatty females, converse in low-pitched rumbles that often are missed by human ears, according to two related studies, which have been accepted for publication in the journal Animal Behavior.

Similar to humans ignoring conversations at other tables in a restaurant, elephant strangers do not pay much attention to each other.

"Female friends exchange rumbles even when they are out of sight from one another, and their voices differ from one another, so I believe that they can recognize each other by their voices alone, just as humans and many other social animals can do," said Joseph Soltis, who led the study.

He added, "Females that have known each other for many decades, for example, often engage in rumble exchanges, but females who haven't known each other very long do not respond to each other's calls."

Soltis, a research scientist in bioacoustics at Disney's Animal Kingdom, and his colleagues placed radio collars on six female elephants that live at the park. All recorded sounds were computer-analyzed and compared with filmed footage of the elephants.

The recordings indicate that each elephant has its own voice.

"The shapes of their mouths and trunks cause the rumbles from females to sound different from one another," Soltis told Animal Planet News.

"It's the same for humans. In the case of our elephants, the sizes and shapes of their vocal tracts, including their trunks, shapes the unique sounds of their rumbles and makes each elephant sound a little different."

He and his colleagues discovered that elephant rumbles became jittery when the animals appeared to feel threatened, such as when a dominant female marched by.

Soltis believes fear, and other emotions, likely are conveyed in elephant rumbles.

Dominant females within the herd did not necessarily vocalize more than other elephants.

Ovulation cycles also were not a factor, but the closeness of relationships were. Elephant friends and members of families conversed more with each other, according to the study.

Jeff Kinzley, elephant manager at the Oakland Zoo, agrees with the findings.

"I've even noticed that elephants will have back and forth conversations for a long time before they all suddenly turn around and do something, like go to eat," Kinzley told Animal Planet News.

"They wind up walking in a certain order, so it is as though they were deciding who can eat after the matriarch."

Kinzley added that males converse with each other too, only not as much and usually more when they seem happy.

"Low and slow rumbles seem to indicate happiness," Kinzley said. "We sometimes hear this from both males and females when they appear glad to see us or when they are lounging at a comfortable spot with their trunks resting flat on the ground."