By Michael Pardo, Cornell University & Open University of Sri Lanka

Tulita, [802], [802]’s calf, and a sub-adult female stood nearly motionless under the low-hanging canopy of the maila tree.  Their heads drooped low and their trunks rested on the ground as they huddled together in the shade, seeking respite from the blazing noonday sun.  The only movement was the occasional swish of a tail, in an attempt to swat away some pesky insect.  A group of jabbering tourists pulled up in a small caravan of jeeps, but the elephants paid them no heed. Suddenly, two low growls echoed across the road over the noise of the human onlookers—deep, rumbling sounds like the purring of a truck-sized cat.  They were followed by two roar-rumbles, more urgent-sounding vocalizations where a loud bellow precedes the softer rumbling component.  One more call emanated from the tall undergrowth before the sub-adult female finally answered it.  Her response was immediately answered in turn, initiating a brief exchange of vocalizations between the unseen elephant and the sub-adult under the maila tree.  As I scanned the shrubs expectantly, they soon parted, revealing the dust-covered forehead of a small female elephant.  The newcomer stepped fully out of the thorny vegetation, displaying ears with a noticeable flap in front and a long, narrow lobe.  It was Tushari, a known associate of the elephants under the tree.

As Tushari walked briskly towards her fellows, she gave a loud rumble, which was immediately answered in kind.  As she neared the group, they shifted over to make room for her in the shade, growling softly to one another. But Tushari hadn’t been resting with the group for five minutes when the silence was rent by two long-roars coming from back across the road.  Without hesitation, she abandoned her spot in the shade and hurried back in the direction she had come.  Long-roars are often given by juveniles who are separated from their group or in distress.  Was this Tushari’s calf who had been left behind?  Whoever it was, we heard three more distant calls as Tushari quickly retraced her steps.  She responded with a thunderous long-roar-rumble as she went, which was absolutely earsplitting even at the distance of 40 meters.  Tushari bulldozed her way back through the wall of spiky shrubs and was gone.  For several more minutes, we heard a back-and-forth exchange of ever-quieter roar-rumbles before they eventually faded off into the distance. We know that African elephants use rumbles to keep in vocal contact with one another over long distances, and to find one another when they are too far apart for vision or smell to be of any use.   In order for this system to be maximally effective, the elephants must be able to discriminate the calls of familiar individuals from the calls of strangers.  And research on African elephants has shown that this is exactly what they do.  But when it comes to the Asian species, we still know very little about how their communication system works.  Do Asian elephants also use rumbles and similar calls to find one another when separated?  I think that they probably do, and Tushari’s behavior seems like it could be a perfect example of this.  But without hard data, we can’t say for sure.

Listen to it here.

Within the next month, I hope to begin the first ever experiments to test whether Asian elephants can discriminate between the calls of familiar vs. unfamiliar individuals.  Once we have the basic knowledge of how Asian elephants respond to the rumbles of different individuals, a whole host of other questions will be open for investigation.  For example, if we knew that Asian elephants could recognize each other by voice, could we use this information to learn about their intelligence?  We know that Asian elephants have stronger relationships with some individuals than with others.  But how aware are they of the relationships between their fellows?  What if we played back the calls of two elephants who rarely hang out together, such that it sounded as if they were coming from the same group?  Would the elephants who hear this react with greater surprise than if we played back the calls of two individuals who are regularly seen in each other’s company?  It is only by first addressing the basics of Asian elephant communication that we will ultimately be able to answer such fine-tuned and fascinating questions.