Vocal communication plays an outsized role in how social animals survive in the wild.
A loud cry from a baby attracts the attention of a parent. A scream can warn others of a predator lurking nearby.
Humans have developed thousands of languages, spoken and signed, to share information, ideas, and emotions — yet they’re not alone among the earth’s life forms in communicating in complicated ways and out loud.
Elephants live long lives, up to around 70 years, and in this time their herds often split and merge. To navigate these changes, these giants have developed a complex system of sounds, from low-frequency rumbles and roars to high-frequency squeaks and chirps, to stay in touch with each other.
Most of what we know about elephants’ use of sounds to communicate comes from studies of African elephants (genus Loxodonta). We don’t know much about Asian elephants (genus Elephas), the species native to India and other tropical and subtropical forests of Asia.
Understanding the differences in vocal communication between elephant species is nontrivial because African and Asian elephants aren’t just distant cousins roaming different lands. They are entirely different species with unique habits, habitats, and adaptations.
In a study published in the journal Mammalian Biology on December 23, 2024, researchers compared the calls of Asian elephants based on their age, sex, and behaviour. They found the duration of trumpets remained fairly consistent across all age classes for both male and female Asian elephants but roars and roar-rumbles got longer with age.
“Every behaviour of [Asian] elephants is fascinating to witness, and their acoustic communication makes it even more remarkable because of elephants’ capabilities to switch between very high-frequency to very low-frequency sounds,” Nachiketha Sharma, the study’s first author and a PhD student at the Centre for Ecological Sciences, Indian Institute of Science, Bengaluru, said.
A vocal repertoire
Through thick forests and rough terrain, the researchers set out in pursuit of the secrets of the vocal communications of Asian elephants.
These animals roam freely in the outdoors and talk to each other using four main types of calls: trumpets, roars, rumbles, and chirps. They combine them in different ways, called combination calls, to convey different messages.
The researchers divided the vocalisations into high and low frequencies based on whether human ears could hear them.
Translating the trumpet
Each call carries a specific meaning and function. The most common high-frequency vocalisations, which both the Asian and the African savannah elephants can produce, are trumpets — the iconic sound uniquely associated with elephants.
According to some mathematical models, these elephants may be producing the trumpets by blowing air in sudden bursts through the trunk, a form of “second voice” that doesn’t require the vocal cords to be involved.
Researchers had previously believed Asian elephants trumpeted chiefly to communicate disturbances caused by humans and other troublesome species. The new study isn’t so sure. “Our study reveals that trumpets are generated in a variety of contexts, including social interactions, play, and in agonistic interactions both within and between groups,” Sharma said.
He also added that the study documented the first instance of combination calls in a southern Indian population of Asian elephants. The researchers found the roar-rumble in particular to possibly serve multiple functions, including maintaining contact and signalling disturbances.
‘As quiet as possible’
The team also tackled a fundamental question: whether Asian elephants’ high-frequency vocalisations differed by age and sex.
“For a holistic understanding of any communication system, it is vital to address fundamental questions such as age and sex differences,” Sharma said. “Once we know these basic differences, we can dig deeper or ask more questions related to the possible reasons behind such variations as well as the functions associated with a particular call type.”
The team set up recording equipment in the protected areas of Bandipur National Park and Mudumalai National Park, which are 75 km apart. Both parks are home to large populations of Asian elephants, with an estimated 1,025 in the former and 300 in the latter.
The study focused on elephants that moved freely between these parks.
“Recording vocalisations can be quite a challenge,” Sharma said. “We spent hours following elephants, trying to stay as quiet as possible to avoid any background noise that could interfere with [the] recordings,” Sharma said.
The team also collected data of elephant vocalisations recorded over two years from diverse habitats, including grasslands, forests, saltlicks, and water bodies.
Putting them together, the team stumbled upon an intriguing pattern.
Younger elephants, both male and female, produced calls of a higher pitch to attract the attention of their herd mates and establish their presence. On the other hand, the older ones used lower-pitched calls for the same purpose.
According to the paper, these differences could be shaped by changes in body size and vocalisation mechanisms as the elephants aged.
The researchers also found that the role of roars issued by Asian elephant calves closely mirrored those of their African cousins. The infants used these powerful calls to get the attention of the adults in a herd and signal their emotional states.
To the researchers, this meant the roar serves a universal purpose that could be highly conserved across elephant species.
A sound library
This study laid the groundwork for scientists to understand the various sounds Asian elephants use and set the stage for further exploring the acoustic behaviours of free-ranging populations.
The researchers also said this work is just the beginning. “There is a lot more for us to uncover to truly appreciate the complex world of elephant acoustic communication,” Sharma added.
The team also plans to launch a project to explore and understand the soundscapes of Asian elephants in both wild and captive environments. As part of this initiative, the researchers are curating an ‘Asian Elephant Sound Library’ that will soon be accessible to the public for education and scientific research.
Sanjukta Mondal is a chemist-turned-science-writer with experience in writing popular science articles and scripts for STEM YouTube channels.
Published – February 12, 2025 05:30 am IST
