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African Elephant Vocal Communication

Discoveries


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. In that process, we discovered two new vocalizations not previously described by scientists, 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 by something such as an approaching animal. 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.

 


Best friends exchange rumbles in conversational sequences

 

Female African elephants are known to produce clusters of rumbles that often overlap one another, 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 and can’t see each other, they may use these rumble vocalizations to stay in contact with each other.

 

Click here to listen to the cluster of rumbles.


Each elephant has a distinct voice

 

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 voice activated phone systems can understand our voices when we respond to a command such as “say or press one”. Using the same “human speech recognition technology”, our colleagues at Marquette University have developed special software to accurately identify individual elephant rumbles, showing that they have unique voices just as humans do. So not only do best friends talk to each other by exchanging rumbles, they probably can also recognize each other by their voices alone. What a great way to keep track of everyone when they are out of sight. It’s the elephant version of a cell phone.

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

 


Female rumbles may signal their reproductive state to males

 

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 just before ovulation. Together with researchers at Marquette University, 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.


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

 

African elephants express emotion in their voices

 

When humans are nervous or scared it is common that their voices get shaky or start to quiver. It turns out that the same thing happens to elephants. When female elephants are around dominant animals their rumbles become shaky and jittery. Now we are trying to figure out if these "nervous rumbles" communicate anything to other elephants. Perhaps they signal submission to dominant animals so they can be left alone, or maybe they are cries for help from friends who are out of sight but might hear them and come to help.

 

Click here to to listen to the nervous rumbles.



This graph shows an example of a “calm” and “tense” voice. Calm voices have vibrations with even intervals, resulting in a sound with a more constant and even pitch. Tense voices have vibrations with uneven intervals, with quick changes in pitch over time, or a “jittery voice”.


New research

 

New Research

We are currently collecting more vocal and behavioral data in the new 2006 study on our elephant herd of 7 adult females and 3 infants. Our new digital audio-recording collars are on the adults, but they are picking up lots of infant rumbles, snorts and screams, so soon we will have good information on infant communication too. We are also hearing some rumbles that appear to be made while adult females are under water, so stay tuned for more information on that as well.

 

Click here to listen to “protest rumbles” from a 2-month old female calf who really wants to nurse and isn’t getting her way.



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

History

Recording Elephant Vocalizations and Behavior
Check out our elephant collar audio-recording system

Meet our Research Team
See the Wildlife Tracking Center

Read our publications
Examine our findings in detail



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Updated: May 8, 2008