Wildlife's secret conversations use infrasound
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Wildlife's secret conversations use infrasound
Nature’s most impressive conversations happen at frequencies we cannot hear. While humans perceive sounds between 20 and 20,000 hertz, many animals have evolved to communicate using infrasound. These acoustic waves, below 20 Hz, can travel extraordinary distances through air, water, and even solid ground.
This invisible network of communication allows elephants on African savannahs to coordinate across kilometers, enables whales to sing across ocean basins, and helps cassowaries navigate dense tropical forests where visual contact is nearly impossible.
The physics of infrasound
Unlike high-frequency sounds that bounce off obstacles, infrasonic waves pass through objects with minimal interference. This physical property makes infrasound ideal for long-range communication in challenging environments. The lower the frequency, the farther the sound can travel.
According to research from the Cornell Lab of Ornithology’s Elephant Listening Project, these low-frequency vibrations can penetrate buildings, cut through dense vegetation, and even traverse mountains. Because infrasound travels through objects rather than reflecting off them, it also becomes difficult to localize. This is a drawback that animals have overcome through other sensory strategies.
Long-distance networks
African elephants represent perhaps the most extensively studied example of infrasound communication. Katy Payne, founder of the Elephant Listening Project, discovered this ability in 1984 while observing Asian elephants at a Portland zoo. She felt a throbbing sensation in the air, similar to the vibrations of a pipe organ, and realized she was sensing rather than hearing the elephants communicate.
Subsequent field research revealed the remarkable scope of elephant acoustic networks. Playback experiments on East African savannahs demonstrated that elephants respond to calls from as far as 2 kilometers away. Because researchers cannot replicate elephant calls at their natural volume, scientists estimate the actual detection range extends to 4 kilometers under favorable conditions.
This creates a potential listening area of approximately 50 square kilometers. However, atmospheric conditions can dramatically alter this range. During evening hours on the savannah, temperature inversions create an acoustic ceiling that bounces sound waves back toward the ground, potentially expanding the communication network tenfold to 300 square kilometers.
In tropical forests where elephants also dwell, background noise from insects, birds, and weather reduces effective communication distance. However, during the quietest periods, elephant rumbles can still travel up to 3 kilometers through dense vegetation.
Elephants may even be better at distinguishing their own infrasonic signals from background noise than researchers initially thought. This suggests that communication ranges in forests could exceed current estimates
The applications extend beyond social coordination. Research published in the journal Animals suggests that elephants can detect gathering thunderstorms more than 100 kilometers away through infrasonic signals. At the end of dry seasons in sub-Saharan Africa, this ability could be life-saving, allowing herds to locate distant water sources. Anecdotal evidence from the 2004 Indian Ocean tsunami even suggests that elephants in Thailand may have detected the approaching disaster through infrasonic precursors.
Recent studies highlighted on Earth.com have revealed that elephants use specific vocal signatures to identify individuals. They effectively call each other by name using these low-frequency vocalizations.
Birds and reptiles also use infrasound
Cassowaries, massive flightless birds inhabiting the dense rainforests of Papua New Guinea and northern Australia, also communicate using near-infrasonic frequencies. Research published in The Auk documented that dwarf cassowaries (Casuarius bennetti) produce fundamental frequencies as low as 23 Hz, while southern cassowaries (C. casuarius) generate sounds at 32 Hz.
These booming vocalizations represent ideal adaptations for solitary birds dispersed across rugged, vegetation-choked terrain. The low frequencies penetrate the forest canopy far more effectively than higher-pitched calls, allowing cassowaries to maintain acoustic contact even when separated by considerable distances or visual obstacles.
Crocodilians employ infrasound in spectacular courtship displays. During mating season, many crocodilian species perform what researchers call a “water dance.” The dance is actually the animals vibrating their bodies to create infrasound that makes the shallow water on their backs ripple in mesmerizing patterns. Males combine these infrasonic vibrations with head slaps on the water surface and audible roars to attract females.
Vladimir Dinets, who received his PhD in zoology from the University of Miami, documented variable crocodilian vocalizations during six years of global fieldwork. His book Dragon Songs describes witnessing groups of up to 70 alligators performing synchronized mating choruses with infrasound components. This behavior was previously unknown in scientific literature.
Tigers add another dimension to terrestrial infrasound communication. Research published in The Journal of the Acoustical Society of America by Elizabeth von Muggenthaler at the Fauna Communications Research Institute revealed that tiger roars contain fundamental frequencies around 18 Hz, with some vocalizations dipping even lower.
These paralyzing roars serve multiple functions: warning rival males away from territories, attracting potential mates, and possibly stunning prey. The combination of audible and infrasonic components creates the distinctive, intimidating effect of a tiger’s roar.
Marine mammals master oceanic infrasound
Baleen whales, including blue whales (Balaenoptera musculus) and fin whales (B. physalus), produce some of nature’s most powerful infrasonic signals. Their calls, optimized for transmission through the ocean’s deep sound channel, can theoretically travel across entire ocean basins.
Research in The Journal of the Acoustical Society of America has documented that fin whales produce calls in the 15-25 Hz range, while blue whales’ vocalizations can extend even lower. These sounds serve multiple purposes throughout the year, including coordination during feeding in high-latitude waters and potential reproductive communication.
Unlike the initial hypothesis that linked whale songs exclusively to mating seasons, more recent evidence shows that blue and fin whales produce infrasonic calls during feeding seasons in productive waters where females congregate. This suggests a more complex communication system than previously understood.
Earth.com has previously covered the diverse communication strategies animals employ, from whale songs to elephant rumbles, highlighting the remarkable variety of acoustic adaptations across species.
The evolutionary mystery persists
Scientists continue investigating how and why infrasound communication evolved independently in such diverse lineages. The ability appears in mammals as diverse as elephants and whales, in birds such as cassowaries, and in reptiles, including crocodilians. The discovery suggests a strong selective pressure favoring this adaptation.
Body size appears to correlate with the capability to produce infrasound. Larger animals generally possess the anatomical structures necessary to generate low-frequency vibrations, from elongated vocal cords in elephants to specialized laryngeal structures in baleen whales. However, the evolutionary pathways that led to these adaptations remain under investigation.
Environmental factors likely played crucial roles. Animals inhabiting dense forests, vast savannahs, or expansive oceans face communication challenges that high-frequency sounds cannot overcome. Infrasound provides an elegant solution, allowing coordination across distances that would otherwise fracture social groups or prevent mate location.
As acoustic monitoring technology advances, researchers continue discovering new dimensions of infrasound communication. The field remains relatively young, with many unanswered questions about the full extent and sophistication of these invisible conversations happening all around us.
The information presented draws from research by the Cornell Lab of Ornithology, studies published in The Journal of the Acoustical Society of America, and field observations documented by scientists including Katy Payne, Vladimir Dinets, Andrew Mack, and Elizabeth von Muggenthaler.