Tuesday, May 13, 2014

Call Me Maybe: Elephant Vocalizations

By Sophie Wasserman

As you may have seen in our recent Youtube video (Click Here), the Think Elephants International (TEI) research team is currently spending a few hours each day recording the various sounds made by our local, vocal elephants. TEI’s goal is to build up a database for use in future studies but the reality involves a lot of sitting, waiting, and wishing that you hadn’t forgotten bug spray. As we move forward with our project, we've compiled some useful information and a handy identification guide for the typical vocalizations (or sounds used to communicate) of Asian elephants, helpful for your next safari, jungle trek, or trip to your neighborhood zoo. 
While our Research Diaries video above showcases the more high-tech recording equipment, it’s important to remember that in the field, our most essential tools are pen and paper. Although the microphone allows us to preserve the vocalizations, these sound bytes are useless to us without also writing down which elephant made the call, the elephant’s posture and position, the names of other elephants within range, and the circumstances that prompted the call. In other words, the key to interpreting elephant vocalizations is context. For a good example, just watch the clips below!

Pretty intimidating, right? Sounds like some serious stuff is going down. Now watch the clip again—now with the audio and video.

This time, you get a completely different story. Thangmo, the initial elephant, and Lamyai, her arriving companion, are actually very close friends. Their roars and trumpets are expressing excitement at their reunion, as opposed to the terror the sound alone might suggest. We can tell they are not at ease by the way their ears are pinned straight and their tails are raised, but they twine their trunks and relax their ears when they finally meet, suggesting that these elephants are simply exchanging an exuberant greeting. Elephants tend to vocalize at times of high emotional arousal, with similar (to our ears at least) sounds conveying both positive reactions, such as excitement or playfulness, and negative reactions, such as anger, agitation, or fear. In this way, body posture, environment, and even level of affiliation between individuals are all crucial factors when trying to decipher the acoustic communication of elephants.
Male Phuki often rumbles more than our ladies
Though the majority of studies of elephant vocalizations have been completed with African elephants, a few have looked specifically at their Asian counterparts. In general, studies of Asian elephant classify their vocalizations into four main groups: rumbles, trumpets, chirps (which African elephants do not make) and roars. Elephants do make other sounds, but noises like these, including what some call “snorts” or “booms,” are classified as non-vocal sounds and are thus not as intensely studied. Keep in mind that elephant vocalizations are highly complex and variable, so defining a "standard" call is difficult. The examples below are provided to give you an idea  of what a particular category of vocalization could sound like.

Rumble: (from Boonjan, as another elephant arrived)

Rumbles are unique in that they contain infrasonic components, meaning part of the vocalization is below our hearing range. They have the longest duration of any call, typically lasting about five to six seconds. Elephants rumble during interactions within a herd, such as to assemble herd members when leaving a watering hole or to contact members who were separated from the herd, as well as when initiating interactions between herds. Rumbles are also integral to mating behaviors; males in musth and females in estrous produce specific rumbles that signal their body state to elephants far and wide.

Trumpet:  (from Lynchee, at the shower station)

Trumpets are loud, high frequency calls that last, on average, about one second. As seen in the clips above, trumpets are a very versatile vocalization; the three situations found most likely to elicit trumpets are play (especially in younger elephants), disturbance by humans or other animals, and aggression (such as while charging another species or vehicle).

Chirp: (from Lynchee, at the shower station)

Chirps are short, squeaky blasts lasting less than a few tenths of a second, usually produced in a series of 2-8. In the wild, young elephants rarely, if ever, chirp. Chirps seem to indicate confusion or alarm and are usually accompanied by confused running or bunching of herd members. In captivity, elephants have learned to associate chirping, which humans find charming and cute, with food rewards from their mahouts, and often use chirps as a way to ask for bananas or other treats.

Roar: (from Lanna, arriving in the grasslands)

If the clip above sounds familiar, it might be because sound editors for the film Jurassic Park mixed together elephant recordings with tigers, lions and alligators to get the perfect roar for their T.Rex. The mighty elephant roar usually lasts a little over two seconds and can reach over 100 decibels (that’s a little less than a jet engine taking off!). As you might predict, roars are used in instances of aggression, but also frequently used in play as well as upon first arrival in a new location.

Now that you know the four main types of elephant vocalizations, as well as the importance of context in understanding elephant acoustic communication, stay tuned for next month’s look at how elephants produce and interpret these calls themselves.

Nair, S., Balakrishnan, R., Seelamantula, C. S., & Sukumar, R. (2009). Vocalizations of wild Asian elephants (Elephas maximus): Structural classification and social context. The Journal of the Acoustical Society of America, 126(5), 2768-2778.

1 comment:

  1. All the contents you mentioned in post is too good and can be very useful. I will keep it in mind, thanks for sharing the information keep updating, looking forward for more posts. Thanks
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