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Discoveries in African Elephant Vocal Communication:

The vocal repertoire of African Elephants

The first thing to do when trying to understand the vocal communication system of another species is to figure out how many different types of vocalizations there are. We have found 8 basic types of vocalization in the adult African elephant vocal repertoire, including two new vocalizations first described by our team, the ‘croak’ and the ‘rev.’ The croak is often heard when elephants are exploring the environment with their trunks, and the rev often occurs when elephants are startled. Although trumpets are the most well known elephant vocalization, ‘rumbles’ are the most common and we know most about them.

Click here to listen to the croak.
Click here to listen to the rev.
Click here to listen to the trumpet.

Each elephant has a distinct voice

Click here to listen to the rumbles of two different females.

Although it is difficult for us to detect with our limited hearing, we have shown that our elephants have distinctive sounding voices. We know that we can recognize our friends and family members’ voices without even seeing them. So can elephants. We think they take advantage of this recognition to communicate at long distances.

Best friends exchange rumbles as contact calls

Female African elephants are known to produce rumbles in clusters, but since low-frequency rumbles are difficult to detect no one knew for sure who was talking to whom. Using our customized audio-recording collars, we found that females with the strongest social bonds are responsible for these rumble exchanges, sometimes over relatively long distances. When “best friends” are separated from each other and exchange rumbles, they move closer together. These rumbles are like social magnets that keep closely bonded partners from straying too far from each other. It’s the elephant version of a cell phone.

Click here to listen to the cluster of rumbles.

Female rumbles may signal their reproductive state to males

Click here to listen to a female “mate attraction” rumble.

There is a lot more information in a rumble besides the differences between individuals. Females appear to have ‘mate attraction’ rumbles that signal their reproductive state to distant males. In the wild, males are solitary and usually only visit females for mating, so it could help everyone if female rumbles indicated something about their current fertility. We found that the cycling females in our herd start rumbling much more than usual a little before ovulation. We have shown that these “pre-ovulatory” rumbles are distinct from “normal” rumbles, involving a lowering of the pitch of the call. Males may listen for these rumbles so they can find females who will soon become ready to mate. But what happens when the male gets into the female herd?  When we introduced a male into our herd containing cycling females, the females became less vocal, and males switched to using olfactory cues to determine female fertility.

The graph shows a female’s hormonal cycle. The black line shows peaks of Luteinizing Hormone, or LH. Unlike most mammals, elephants have two LH peaks per cycle, and the second one results in ovulation. The red bars show how her rumbling increases just before the first LH peak (no ovulation) and remains relatively high up to ovulation, compared to other times in her cycle.

African elephants express emotion in their voices

Click here to to listen to the "temper tantrum" rumbles from a 3-month old female calf who wants to nurse and isn't getting her way.

When humans are nervous or upset, it is common that their voices get louder, higher pitched and shaky. It turns out that the same thing happens to elephants. Our baby elephants make loud, high pitched rumbles when they are upset.

Adult female elephants also express emotion in their voices. When subordinates are approached by dominant animals, they make “nervous” rumbles. When they are relaxing alone or hanging out with a friend, they make softer rumbles.

The graph shows an example of a “calm” rumble, recorded from one of our adult females when she was resting and not engaging in social interactions; a “nervous” rumble, which she made when she was approached by a dominant female and had to leave; and a “pleasant” rumble, which she made after being approached by her closely bonded partner and they remained together for a while. Her “nervous” rumble was high-pitched and shaky, and loud and long, compared to her “calm” rumble. The “pleasant” rumble was in between: It was loud and long, and had a modulating pitch, just like the “nervous” rumble. But it was relatively low-pitched and purr-like, like the “calm” rumble. It looks like elephants express different kinds of emotions in their voices, just like people do.

Click here to to listen to the calm, nervous and pleasant rumbles pictured in the graph above.

To learn more about Elephant Communication please visit the links below:

Learn more about the history of elephant communication research at Disney's Animal Kingdom

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Updated: July 26, 2012